JPH0315622A - Port structure of engine - Google Patents

Abstract

PURPOSE:To improve distribution of fuel as well as to reduce flow resistance by forming a cross sectional shape of each of branch parts so that the radius of the inner circumferential part is larger than the radius of the outer circumferential part when a branch middle part of a port is cut in perpendicular to the flow direction. CONSTITUTION:At least an intake port 5 which opens in a combustion chamber 4 of an engine is formed by a common part 51, a branch middle part 54 and each of branch parts 52 and 53. Also, a tip end part of a fuel injection valve 3 is inserted into an escape groove 9 communicated with the intake port 5. In this case, when the intake port 5 is cut in perpendicular to the flow direction of intake air at least at the branch middle part 54, a cross sectional shape of each of the branch parts 52 and 53 is formed so that the radius Ra of the inner circumferential part is in the shape of a semicircle larger than the radius Rb of the outer circumferential part. And each of the branch parts 52 and 53 is formed so that the common part 51 in the shape of a circle is gradually separated in the half-cut state. By this, flow resistance f the intake air is reduced and distribution of fuel is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to the structure of an intake port or exhaust port of an engine.

(Prior Art) Conventionally, the intake port structure of an engine has been configured such that the intake port is branched from one common passage into two branch passages that open into the combustion chamber, and an intake valve is provided in each branch passage. It is known that the intake port opening area per cylinder is increased in this manner to achieve high output (see Japanese Utility Model Publication No. 60-26284).

This type of intake port structure is schematically shown in FIGS. 11 to 16. In these figures, 4 is the combustion chamber, 5a
is an intake port, and 6 is an exhaust port. Intake port 5a
In view of ease of machining, the air passage is constructed by combining passages each having a substantially circular cross-sectional shape when taken perpendicularly to the flow direction of the intake air. For this reason, a common part 51a consisting of one circular common passage and a branch part 52a after branching into two branch passages. 53a, that is, at the mid-branching portion 54a between the beginning of the branching into two branching passages and before the two branching passages completely become two branching passages, there is a roughly gourd-shaped part 54a in which two circular branching passages are connected horizontally. Has a cross-sectional shape,
Moreover, the shape is such that the two branch passages constituting a substantially canopy shape become gradually separated from each other toward the downstream side.

(Problems to be Solved by the Invention) However, when configured as described above, there were the following problems. That is, the intake port 5a has a common portion 51a on the upstream side with a large diameter, and each downstream branch portion 52a . 5
3a as a small diameter, the cross-sectional area of the common part 51a and the two branch parts 52a. It is necessary to make the shape so that the total cross-sectional area of 53a is approximately equal. For this reason, conventionally,
When viewed from the side, the intake port 5a has a shape that is suddenly constricted at the mid-branch portion 54a, and the angle β formed by the central axis of the branch passage (branch angle) is large, and the length of the mid-branch portion 54a is large. The second part is long, and there is a part 54 in the middle of the branch.
The area of the constricted portion 57a (oblique fi1 portion in FIGS. 14 and 15) of the approximately gourd-shaped cross section of a was increased. For this reason, in the conventional structure of the intake port 5a, the mid-branch portion 54
There was a problem that the flow path resistance became large at a. Also,
Since the area of the constricted portion 57a was large, there was a problem in that a large amount of fuel injected from the fuel injection valve 3 provided on the upstream side collided with the constricted portion 57a and adhered thereto.

By the way, in the above intake port structure, each branch portion 5
In order to be able to inject fuel toward the downstream end openings of the fuel injection valves 2a and 53a, a two-hole fuel injection valve having two 11-hole ports at its tip is generally used as the fuel injection valve 3. . In order to introduce the fuel injected from each nozzle of the two-nozzle fuel injection valve 3 into each branch portion 52a, 53a, a pipe extends from the tip of the two-nozzle fuel injection valve 3 toward the intake port 5a. A relief groove 9a is formed which opens into the intake port 5a.

However, conventionally, this escape groove 98
4a, the fuel may be introduced only to one side of the two branch portions 52a and 53a, resulting in a problem of poor fuel distribution.

In view of the above circumstances, the present invention provides an engine port structure that can reduce intake or exhaust flow resistance and improve fuel distribution in an intake port equipped with a two-injection fuel injection valve. This is what we are trying to provide.

[Means to solve the problem]

An engine port structure according to the present invention is an engine port structure in which a port is shaped so that one common passage branches into two branch passages and opens into a combustion chamber. Completely 2 since I started
In the middle of the branch before becoming two branch passages, each branch passage is configured so that the radius of the inner peripheral part of the cross section taken perpendicular to the flow direction is larger than the radius of the same outer part. It is something.

Further, the port is an intake port, and a two-injector fuel injection valve has two injection ports in the same part of the port and injects fuel from each injection port toward the downstream end opening of each branch passage. is provided, it is preferable that a relief groove is formed in the circumference of the port, extending from each injection port of the two-injector fuel injection valve to the downstream end of the mid-branch portion.

(Function) According to the above configuration, in the middle of the branch, the circular common passage is gradually cut into half as it goes from the common passage side to the branch passage side, so that it becomes two branch passages. The intake air passing through the circular common passage is split into two branch passages along the airflow direction in the common passage, or the exhaust air passing through each of the two branch passages is divided into two branch passages. They merge into a circular common passage along the direction.

Furthermore, since the relief groove extends to the downstream end of the mid-branch portion, the fuel injected from the injection port of the two-injector fuel injection valve is guided by the relief groove to the downstream end of the mid-branch portion, that is, into the two branch passages. The fuel is guided to a completely branched position, and the fuel injected toward each branch passage is reliably supplied to each branch passage.

[Embodiment] FIGS. 1 to 10 show an embodiment in which the present invention is applied to the structure of an intake port.

In these figures, 1 is a V-type engine, which is comprised of a cylinder block 11, a pair of left and right cylinder heads 12, and a cylinder force bar 13.

An intake manifold 2 forming an intake passage 21 is connected to each cylinder head 12 . A surge tank 22 and a throttle valve 23 are provided upstream of the intake manifold 2, and a valve 24 for changing the natural frequency of intake air is provided within the surge tank 22. Furthermore, a fuel injection valve 3 is installed at the downstream end of the intake manifold 2.

Inside the cylinder block 11, a piston 14 is provided for each cylinder.
A combustion chamber 4, an intake port 5, and an exhaust port 6 are formed in the cylinder head 12 for each cylinder. The intake and exhaust ports 5.6 branch from one common passage into two branch passages and open into the combustion chamber 4, and a common part 51.61 composed of one common passage
, the middle part of the branch after it starts to branch into two branch passages and before it completely becomes two branch passages, and the part 54.
Branch section 52, 53, 62, 63 branched into two branch passages
It consists of Branch portion 52.5 of the intake port 5
3 and the branch portions 62 and 63 of the exhaust port 6 are each provided with an intake valve 7 that is opened and closed by a valve mechanism (not shown).
and an exhaust valve 8 are provided.

The tip of the fuel injection valve 3 is inserted into one end 91 of a relief valve 9 that communicates with the intake port 5.

As the fuel injection valve 3, a two-nozzle fuel injection valve is used in which two injection ports 33 are formed at the tip, as shown in FIG. 9. Each injection port 33 of this fuel injection valve 3 is directed toward the downstream end opening of each branch 52 , 53 of the intake port 5 .

When the common portion 51 of the intake port 5 is cut perpendicularly to the flow direction of the intake air, one large circular cross-sectional shape appears, as shown in FIG. Furthermore, when the mid-branch portion 54 is cut perpendicularly to the flow direction of the intake air, the cross-sectional shape is obtained by superimposing the cross-sectional shapes of the two branch passages side by side, as shown in FIGS. 4 to 6. appears, and the cross-sectional shape of each branch passage is such that the radius Ra of the inner peripheral part is the radius Rb of the outer local part.
It has a larger, almost semicircular shape. Furthermore, if the branch parts 52 and 53 are cut perpendicularly to the flow direction of the intake air,
As shown in FIG. 7 and FIG. 8, the cross-sectional shapes of two completely branched branch passages appear, and the cross-sectional shape of each branch passage is such that on the upstream side, the radius Ra of the inner circumference is the radius Rb of the outer circumference. It has a larger semicircular shape, and the radius Ra of the inner circumferential part gradually becomes smaller as it goes downstream, and finally, at the downstream end opening, the radius Ra of the inner circumferential part becomes the radius of the same outer part. It is equal to Rb and has a circular shape.

As described above, the intake port 5 is configured so that the radius Ra of the inner peripheral part of the cross section taken perpendicularly to the flow direction is larger than the radius Rb of the outer peripheral part of each branch passage at the intermediate branching part 54. It is configured. Therefore, the branching angle α becomes smaller than the conventional branching angle β. That is, in the conventional configuration, since the cross-sectional shape of each branch passage was circular, when the center axes of the two branch passages were separated by a distance twice the radius Rc of each branch passage, the two branch passages It will be completely branched out. On the other hand, according to the configuration of the present invention,
Since the cross-sectional shape of each branch passage is approximately semicircular, the two branch passages can be completely branched by just slightly separating the center axes of the two branch passages. Therefore, the branching angle α can be made smaller than in the past, and the time from the start of branching to the end of branching can be shortened, so that the length (1) of the part 54 in the middle of branching can be shortened.

Moreover, in the intermediate branching section 54, the circular common passage is gradually cut into two branch passages as it goes from the common passage side to the branch passage side, so that the common passage is divided into two branch passages. The height h and the height h of the branch passage are almost equal. Therefore, the intake port 5 is not suddenly constricted at the mid-branch portion 54 when viewed from the side. Further, in the intermediate branching portion 54, since the radius Ra of the inner local portion is large, the constricted portion of the approximately gourd-shaped cross section (shaded portion 57 in FIGS. 5 and 6) becomes narrower. That is, the area of the constricted portion 57 is smaller than that of the conventional case.

As described above, according to the configuration of the present invention, it is possible to reduce the branch angle α, prevent sudden narrowing at the mid-branch portion 54, and shorten the length of the mid-branch portion 54. can do. Therefore, the intake air that has passed through the common passage is smoothly introduced into the two branch passages without changing the air flow direction and without interfering with each other at the intermediate branch portion 54.

Further, since the area of the constricted portion 57 can be made small, it is possible to prevent a large amount of fuel injected from the fuel injection valve 3 from breaking into the constricted portion 57 and adhering to the constricted portion 57.

Moreover, in the configuration of this example, the radius Ra of the inner circumferential portion of each branch passage becomes gradually larger toward the downstream side of the branch part 52, 53 after completely branching into two branch passages, and finally The downstream end opening is configured to have a radius Rb equal to the outer peripheral portion. Therefore, the intake air can flow smoothly without resistance even at the branch portions 52 and 53.

The above-mentioned relief groove 9 passes through the downstream end of the intake manifold 2, and the other end 92 is connected to the mid-branch portion 54 of the intake port 5.
extends to the downstream end of the Therefore, the fuel injected from the injection port 33 of the fuel injection valve 3 toward each branch portion 52.53 of the intake port 5 is reliably directed to the target branch portion 52.53.
Introduced in 53. That is, the fuel injected toward one branch 52 is reliably introduced into one branch 52 without entering the other branch 53, and the fuel injected toward the other branch 53 is One branch 5
2, and is reliably introduced into the other branch 53.

Note that the port structure of the present invention may be applied to the exhaust port 6. In addition, the portion of the branch passage where the radius of the inner circumferential portion of a cross section taken perpendicularly to the flow direction is larger than the radius of the outer circumferential portion may be only the intermediate portion of the branch.

(Effects of the Invention) In the engine port structure according to the present invention, at least in the middle of the branch, the radius of the inner circumference of each branch passage in a cross section cut perpendicular to the flow direction is greater than the radius of the outer circumference. It is designed to be large. Therefore, in the middle of the branch, as you go from the common passage side to the branch passage side,
The circular common passage is gradually separated into two branch passages, and the intake air passing through the circular common passage is divided into two branches along the airflow direction in the common passage. The exhaust gases are smoothly branched into the branch passage, or the exhaust gas passing through each of the two branch passages is smoothly merged into the circular common passage along the airflow direction in the branch passage.

Therefore, the flow resistance of intake and exhaust air can be reduced.

Further, the port is an intake port, and the two-injector fuel injection valve has an injection port of 2fI1 around the port and injects fuel from each control port toward the downstream end opening of each branch passage. If a relief groove is formed around the port that extends from each nozzle of the two-nozzle fuel injection valve to the downstream end of the mid-branching part, it will be possible to prevent the injection of copper from the nozzle of the two-nozzle fuel injector. Since the fuel is guided by the relief groove to the downstream end of the intermediate part of the branch, that is, to the position where it completely branches into two branch passages, the fuel injected toward that passage is reliably supplied to each branch passage. This improves fuel distribution.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the engine port structure according to the present invention, FIG. 2 is a schematic plan view thereof, FIG. 3 is a sectional view taken along the line T in FIG. 1, and FIG. IV-r in Figure 1
5 is a sectional view taken along the VV line in Fig. 1, Fig. 6 is a sectional view taken along the Vl-Vl line in Fig. 1, and Fig. 7 is a sectional view taken from ■-■ in Fig. 1.
8 is a sectional view taken along the line ■-■ in FIG. 1, FIG. 9 is a sectional view of the tip of the fuel injection valve, and FIG. 10 is an overall front view of a V-type engine to which this embodiment is applied. , FIG. 11 is a schematic plan view of a conventional engine port structure, FIG. 12 is a schematic vertical sectional view thereof, FIG. 13 is a sectional view along the cutting line of FIG. -XIi line sectional view, 1st 5[[
12 is a sectional view taken along the line Xv-Xv, and FIG. 16 is a sectional view taken along the line Xv-Xv in
It is a sectional view taken along the line VI-XVI. 3...2-nozzle fuel injection valve, 4...combustion chamber, 5...
Intake port, 6... Exhaust port, 9... Relief groove,
33... Injection port of a two-nozzle fuel injection valve, 54... Branch midway portion, Ra... Radius of the inner same part, Rb... Radius of the outer peripheral part.

Claims (1)

[Claims] 1. In the port structure of a soil engine in which a port is formed so that one common passage branches into two branch passages and opens into the combustion chamber, at least after the port starts to branch into two branch passages. In the intermediate part of the branch before completely becoming two branch passages, each branch passage is configured such that the radius of the inner periphery of the cross section cut perpendicular to the flow direction is larger than the radius of the outer periphery. The engine port structure is characterized by: 2. A two-injector fuel injection system in which the port is an intake port, and the port has two injection ports around the port, and fuel is injected from each injection port toward the downstream end opening of each branch passage. 2. The port structure for an engine according to claim 1, further comprising a valve and a relief groove extending from each injection port of the two-injector fuel injection valve to a downstream end of the mid-branch portion.