JP3724353B2 - gasket - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is related to a gasket (intake gasket) which is interposed between the cylinder head and the box-type intake manifold of the engine.
[0002]
[Prior art]
In recent years, diesel engines have been improved in size and performance, and in such small high-performance diesel engines, the combustion state is improved by promoting the mixing of fuel and air. The fuel / air mixing can be promoted by a technique such as four-valve or swirl support. For example, the swirl ratio can be improved by using a helical port.
[0003]
Incidentally, the degree of freedom in handling the intake system is restricted due to the recent downsizing of engines, and a box-type intake manifold 11 as shown in FIG. 5A may be used. The box-type intake manifold 11 has a shape in which a branch pipe portion connecting the manifold main body portion 11a to the intake port 12 of the cylinder head 10 is extremely short, and the manifold main body portion 11a is directly connected to the cylinder head 10 via a gasket 21. It has become. As shown in FIG. 5B, the gasket 21 is provided with an opening 22 aligned with the intake port 12, and the opening 22 is formed slightly larger than the diameter of the intake port 12.
[0004]
When the box-type intake manifold 11 as described above is used, the intake passage 13 is suddenly narrowed from the intake manifold 11 to the intake port 12, so that the intake air is strong immediately after the inlet as shown in FIG. Constriction will occur. Such a contraction of the intake air flow causes a reduction in the air supply ratio (a ratio of the supply air supply amount based on the stroke volume of the cylinder) due to a decrease in the intake air amount, and also adversely affects swirl generation. This causes problems such as a decrease in maximum output and an increase in smoke concentration. Further, depending on the shape of the intake manifold 11, as shown in FIG. 5A, an intake port 12A in which a contracted flow is generated in a part of the inlet portion and an intake port 12B in which the entire inlet portion is generated can be formed. Variations in the swirl generation state will occur.
[0005]
The contracted flow is generated more strongly as the direction change angle of the intake air flow at the inlet of the intake port 12 becomes sharper, that is, as R becomes smaller. Therefore, the inlet part of the intake port 12 wants to take as large R as possible. However, in recent small high-performance diesel engines, the space between the intake ports 12 and 12 is narrowed by the above-described four-valve construction, so take a very large R Is difficult.
[0006]
As a solution to the above problem, a technique is known in which a guide plate is provided at the inlet of the intake port 12 and the intake air is guided from the intake manifold 11 into the intake port 12 by the guide plate. For example, in the technique shown in FIG. 6A, the guide plate 24 is integrated with the gasket 23 interposed between the intake manifold 11 and the cylinder head 10. The guide plate 24 is intended to control the flow of intake air flowing from the intake manifold 11 into the intake port 12. For this reason, the guide plate 24 is provided along the intake air inflow path, and an effect is obtained. At the inlet portion of the intake port 12, as shown in FIG. It is arranged along the wall surface on the right side in the figure. By arranging the guide plate 24 in this manner, the contracted flow can be reduced by flowing the intake air smoothly along the wall surface. Further, since the guide plate 24 is integrated with the gasket 23, there is an advantage that the conventional intake manifold 11 can be used as it is.
[0007]
[Problems to be solved by the invention]
However, even if the gasket 23 with the guide plate 24 is used, a contracted flow still occurs on the side where the guide plate 24 is not provided. For this reason, as shown in FIG. 6B, even if the effect is obtained in the intake port 12A in which the contracted flow is generated only on one side, the effect is sufficient in the intake port 12B in which the contracted flow is generated in the entire inlet. Can't get. For this reason, the problem of the fall of the air supply ratio accompanying generation | occurrence | production of a contracted flow, and the dispersion | variation in the swirl production | generation state for every intake port 12 still remains.
[0008]
The present invention was devised in view of such a problem, and an object of the present invention is to provide a gasket capable of reducing the contracted flow of intake air generated in an intake passage extending from a box-type intake manifold to a cylinder head. To do.
[0009]
[Means for Solving the Problems]
To achieve the above object, the gasket of the present invention, and extending from the box-type intake manifold toward the intake port of the cylinder head, intake matched to the intake passage is narrowed by the inlet to the intake port an opening, of the intake opening protrudes into the intake manifold to the side edges to form a plurality of projections reducing the contraction of the intake air flowing into the intake passage in the intake port, a plurality of these A small turbulence is generated in the air flow in the vicinity of the wall surface of the intake passage by the protrusion, and the contracted flow is reduced by the turbulence of the air flow.
[0010]
The protrusion is preferably formed over the entire circumference of the side edge of the intake opening. However, if the range in which the contracted flow is generated in the intake passage is known, at least the range in which the contracted flow is generated What is necessary is just to form. Moreover, it is preferable to form the protrusions finely, for example, in a saw blade shape. Further, it is preferable that the side edge of the intake opening is formed to be equal to or larger than the diameter of the intake passage so that only the tip of the protrusion protrudes into the intake passage.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a gasket according to an embodiment of the present invention will be described with reference to the drawings. Here, FIG. 1 is a plan view showing the configuration of the gasket, and FIG. 2 is a side sectional view showing a mounting state of the gasket. First, the configuration of the gasket will be described with reference to FIGS. .
[0012]
The gasket 1 is an intake gasket interposed between an engine cylinder head 10 and an intake manifold 11 as shown in FIG. Intake manifold 11 is an intake manifold of the box type, contracted flow is in the shape which is easy generated in the intake port 12 entrance.
As shown in FIG. 1A, the gasket 1 is provided with a mounting hole 5 for the cylinder head 10 and an opening (intake opening) 2 that is aligned with the intake passage 13. The opening 2 is formed slightly larger than the inlet of the intake port 12 (and the outlet of the intake manifold 11), and a plurality of fine protrusions 3 are formed on the side edge 2a toward the inside of the opening 2. As shown in FIG. 1B, the protrusion 3 is provided such that its tip protrudes into the intake passage 13, that is, inside the intake port 12 (and the intake manifold 11). And, it is formed at a constant pitch like a saw blade over the entire circumference of the side edge 2a. Further, the opening edge 1a including the protrusion 3 is formed using a metal material in order to ensure rigidity.
[0013]
Next, operations and effects when the gasket 1 having the above configuration is interposed between the cylinder head 10 and the intake manifold 11 will be described with reference to FIGS.
As shown in FIG. 2, the formation of the protrusion 3 protruding from the gasket 1 into the intake passage 13 causes a small disturbance in the air flow in the vicinity of the inner peripheral wall of the intake port 12. The small disturbance of the air suppresses the development of the boundary layer in the vicinity of the inner peripheral wall of the intake port 12 and greatly reduces the contracted flow of the intake air flowing into the intake port 12.
[0014]
Since the contracted flow of the intake air is reduced in this way, the magnitude of the flow coefficient relative to the swirl ratio when the gasket 1 is used is a general gasket (see FIG. 5B) as shown in FIG. Compared to the case of using, it is greatly improved. Therefore, according to the gasket 1, the air supply ratio is improved, stable swirl generation is possible, and effects such as an increase in maximum output and a reduction in smoke concentration can be obtained.
[0015]
Although one embodiment of the gasket of the present invention has been described above, the present invention is not limited to the embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the protrusion 3 is formed over the entire periphery of the opening 2, but for example, it is contracted only to a partial range of the inner peripheral portion as in the intake port 12 </ b> A shown in FIG. For the intake port 12A in which a flow is generated, the protrusion 3 may be formed limited to at least a range where a contracted flow is generated. Of course, even in this case, the protrusion 3 may be formed over the entire circumference of the opening 2.
[0016]
Further, the shape of the projection 3 formed on the side edge 2a of the opening 2 is not limited to that shown in FIG. 1B, and a finer saw blade shape as shown in FIG. It may be pulsed as shown in (b). Moreover, in addition to the formation of the protrusions 3, adding a guide plate as shown in FIG. 6 to the opening 2 is also effective for further reducing the contracted flow.
[0017]
Additionally, the gasket of the present invention can of course be applied to a gasoline engine is not limited to a diesel engine.
[0018]
【The invention's effect】
As described above in detail, according to the gasket of the present invention, the protrusion protruding into the intake passage can cause a small disturbance in the air flow in the vicinity of the inner wall of the intake passage, thereby reducing the contracted flow of the intake air. Therefore, there is an effect that the air supply ratio is improved and stable swirl generation is possible.
[Brief description of the drawings]
1A and 1B are views showing a configuration of a gasket according to an embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is an enlarged view of a portion A in FIG.
FIG. 2 is a side sectional view of an intake port portion showing a mounting state of a gasket as an embodiment of the present invention.
FIG. 3 is a view for explaining the effect of the gasket as one embodiment of the present invention.
FIGS. 4A and 4B are diagrams showing another example of the protrusion shape according to the present invention. FIGS.
5A and 5B are schematic views showing an intake system structure of a conventional diesel engine, in which FIG. 5A is an overall schematic view of the intake system structure including a box-type intake manifold, and FIG. 5B is a conventional general gasket; The top view which shows the structure of (a), (c) is a sectional side view of the intake port part of (a) for demonstrating the conventional subject.
6A is a perspective view showing a configuration of a gasket with a guide plate, and FIG. 6B is a side sectional view of an intake port portion showing a mounted state thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Gasket 2 Opening part 2a Side edge 3 Protrusion 10 Cylinder head 11 Intake manifold 12 Intake port 13 Intake passage

Claims (4)

In the gasket interposed between the cylinder head of the engine and the box-type intake manifold,
And extending from the intake manifold toward the intake port of the cylinder head, in alignment with the intake passage is narrowed by the inlet to the intake port an intake opening,
Projecting intake passage side edge of the intake opening, and a plurality of projections reducing the contraction of the intake air flowing into the intake passage in the intake port is formed, the gasket . The plurality of protrusions are characterized by suppressing the development of a boundary layer near the inner peripheral wall of the intake port by causing a small disturbance in the intake air flowing into the intake passage in the intake port. The gasket according to claim 1. The gasket according to claim 1 or 2, wherein the plurality of protrusions are provided only in a range where the contracted flow of the intake air is generated in the intake port. The gasket according to any one of claims 1 to 3, wherein the plurality of protrusions are formed in a saw blade shape or a pulse shape.

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