JP2962114B2 - Heat insulator for exhaust manifold of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a heat insulator provided for blocking radiant heat from an exhaust manifold of an internal combustion engine.

[0002]

2. Description of the Related Art An internal combustion engine is heated to a high temperature to burn fuel. In particular, an exhaust manifold through which exhaust gas passes generates heat having a large amount of heat. Therefore, in order to radiate the heat generated from the exhaust manifold and the like downward,
Some internal combustion engines are provided with a heat insulator that covers the outer surface of the exhaust manifold with a gap between the exhaust manifold and the outer surface.

For example, Japanese Utility Model Laid-Open No. 2-74518 discloses that
There is disclosed a louver for introducing outside air into the exhaust manifold collecting part, and a louver for exhaust is formed at the rear, and Japanese Utility Model Laid-Open No. 22620 discloses.
It discloses that a bead, which is a protrusion, is provided on the back side of a heat insulator, and outside air is introduced from the bead.

[0004]

However, in such a conventional heat insulator, since the rigidity between the louver and the louver is low, heat generated from the exhaust manifold is trapped, and thermal distortion occurs. In addition to the possibility of cracking the heat insulator, the louver cannot be enlarged to secure rigidity, and the actual outside air introduction area is small.
Sufficient cooling cannot be achieved. In addition, since the high-temperature exhaust manifold assembly is partially cooled, a temperature difference occurs in the exhaust manifold, which may cause cracks in the exhaust manifold.

SUMMARY OF THE INVENTION The present invention has been made in view of such a conventional situation, and provides a heat insulator for covering the outer surface of an exhaust manifold of an internal combustion engine with a gap between the exhaust manifold and the rigidity. It is another object of the present invention to provide a heat insulator capable of uniformly cooling the exhaust manifold by increasing the outside air introduction area.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a heat insulator for covering an outer surface of an exhaust manifold in an internal combustion engine with a gap between the exhaust manifold and the exhaust manifold. And a rising surface that rises smoothly and is adjacent to and opposed to the opening that is opened by the cut-and-raised portion, and a surface that is continuous with the rising surface is formed to have a height equal to or greater than the protruding height of the cut-and-raised portion.

[0007]

According to the above construction, the flow of the air from the outside toward the heat insulator impinges on the surface provided with the cut-and-raised surface and the projecting surface continuously to the surface provided with the cut-and-raised surface. Here, a rising surface that rises smoothly is provided adjacent to and opposed to the opening portion that is opened by cutting and raising, and since the surface that is continuous with the rising surface is the protruding surface, the airflow that hits the rising surface is It is led to the opening which is opened by cutting and raising along the rising surface. On the other hand, since the protruding surface is formed to be higher than the protruding height of the cut-and-raised portion, the air flow is collected on the surface provided with the cut-and-raised portion by the protruding surface.

The air flow collected on the surface provided with the cut and raised portion by the protruding surface or the air flow directly hitting the surface provided with the cut and raised portion flows along the surface provided with the cut and raised portion. However, a cut-and-raised portion is provided on the outer surface, and the air flow flows into the opening that is opened by the cut-and-raised portion, and the air flow is guided to the inner surface of the heat insulator.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 3 showing a first embodiment according to the present invention, an exhaust manifold 1 is connected to a cylinder head (not shown) by a flange portion 2 in order to guide exhaust gas from a combustion chamber (not shown) to an exhaust pipe (not shown). Fixed.

A heat insulator 10 formed of a thin iron plate is covered with a gap 5 between the heat insulator 10 and the outer surface of the exhaust manifold 1. Here, as shown in FIGS. 2 and 3, concave portions 11 and convex portions 21 are alternately provided on the surface of the heat insulator 10, and the concave portions 11 project from the outer surface 11a. A cut-and-raised portion 12 is provided. In the first embodiment, the cut-and-raised portions 12 all face the opening in the same direction, and are further opened at a rising angle f with respect to the normal line. The heights h are also provided substantially equally.

The convex portion 21 has a side surface 25 as a rising surface smoothly continuing to the concave portion 11, and the convex portion 21
Reference numeral 21 denotes a height s equal to or greater than the height h of the cut-and-raised portion 12 projecting from the concave surface 11. Further, in the first embodiment, the side face 25 has the same angle f as the rising angle f of the cut-and-raised portion 12.
Therefore, a parallel gap b is formed by the side surface 25 and the cut-and-raised portion 12.

Further, in the first embodiment, the cutting and raising
A convex portion 31 is also provided at an end of the concave portion 11 which is a side surface as a rising surface with respect to 12, so that the concave portion 11 is surrounded by the convex portion 21 and the convex portion 31. According to the above configuration, the flow of air (indicated by an arrow F in the figure) coming from the outside toward the heat insulator 10 impinges on the concave portion 11 and the convex portion 21 provided on the heat insulator 10.

The air flow F flowing from the direction substantially perpendicular to the heat insulator 10 is deflected by the side surface 25 of the convex portion 21, and flows along the side surface 25. Here, since the side surface 25 is a side surface smoothly continuing to the concave portion 11, the air stream having the streamline deflected is formed.
F flows through the recess 11 as it is, and is guided to the recess 11.

Here, since the projection 21 has a height s which is greater than the height h of the cut-and-raised portion 12 projecting from the concave surface 11, the projection 21
The air flow F acts as a guide to the cut-and-raised portion 12, and the air flow F is actively collected in the concave portion 11 by the convex portion 21. Then, the air flow guided to the concave portion 11 from the convex portion 21
F or although the air flow hits the recess 11 directly so that the flow along the recess 11, 12 cause switching protruding to the outer surface 11a is provided in the recess 11, the airflow F is 該切, Then, the air flow F flows into the gap 12 between the exhaust manifold 1 which is the inner surface of the heat insulator 10.

Further, in the first embodiment, since the parallel gap b is formed by the side surface 25 and the cut-and-raised portion 12, the convex portion is formed.
Air flow F is deflected streamlines to live up to the side surface 25 by the side surface 25 of 21, since the flow into the directly raised streamline and parallel switching 12, more efficient air flow F is the It will flow into the gap 5. Furthermore, in the first embodiment, since the concave portion 11 is surrounded by the convex portion 21 and the convex portion 31, it is possible to secure the rigidity of the heat insulator 10, and it is difficult to input vibration.
The cut-and-raised portion 12 can be made as large as possible, so that a large amount of air flow can be introduced, and the cooling efficiency of the exhaust manifold 1 can be greatly improved.

Further, since the outside air introduced into the exhaust manifold 1 via the heat insulator 10 has a large area for introducing outside air, only a part of the exhaust manifold 1 is not cooled and a crack is generated. Thus, there is an effect that the exhaust manifold 1 can be cooled uniformly. Next, a second embodiment according to the present invention will be described with reference to FIG. 4, but the same components as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.

Also in the second embodiment, concave portions 11 and convex portions 21 are provided on the surface of the heat insulator 10 alternately adjacent to each other. 52 and 55 are provided. Here, in the second embodiment, the cut-and-raised portion 52 and the cut-and-raised portion 55 are opened with their openings facing in different directions. Here, the convex portion 21 has a side surface 45 and a side surface 46 that are smoothly continuous with the concave portion 11, so that the cut and raised portion 52 and the side surface 45 are parallel, and the cut and raised portion 55 and the side surface 46 are It is configured to be parallel. The projection 21 has a height s which is equal to or greater than the height h of the cut-and-raised portions 52 and 55 from the concave surface 11.

Also in the second embodiment, a convex portion is provided at an end of the concave portion 11 which is a side surface with respect to the cut-and-raised portions 52 and 55, so that the concave portion 11 is formed with the convex portions 21 and 22 and the like. It is configured to be surrounded by. According to the above configuration, the flow of air (indicated by arrows 35 and 36 in the drawing) coming from the outside toward the heat insulator 10 impinges on the concave portion 11 and the convex portions 21 and 22 provided on the heat insulator 10. .

The airflow 35 flowing from the direction substantially perpendicular to the heat insulator 10 is deflected by the side surface 45 of the projection 21 and flows along the side surface 45. Here, since the side surface 45 is a side surface smoothly continuing to the concave portion 11, the airflow whose flow line is deflected flows through the concave portion 11 as it is, and is guided to the concave portion 11.

The air flow 35 guided to the concave portion 11 from the convex portion 21 or the air flow directly hitting the concave portion 11
Flow along the outer surface 11a.
The cut-and-raised portion 52 is provided so as to face the side surface 45, and the air flow 35 flows into the cut-and-raised portion 52. It flows into the gap 5 between the exhaust manifold 1 which is the surface.

Further, the air flow 36 flowing from the direction substantially perpendicular to the heat insulator 10 is deflected by the side surface 46 of the convex portion 22 and flows along the side surface 46. Here, since the side surface 46 is a side surface smoothly continuing to the concave portion 11, the airflow whose flow line is deflected flows through the concave portion 11 as it is.
Guided to 11.

The air flow 36 led to the concave portion 11 from the convex portion 22 or the air flow directly hitting the concave portion 11
Flow along the outer surface 11a.
The cut-and-raised portion 55 is provided so as to face the side surface 46, and the air flow 36 flows into the cut-and-raised portion 55, and the air flow flows through the cut-and-raised portion 55 inside the heat insulator 10. It flows into the gap 5 between the exhaust manifold 1 which is the surface.

Further, also in the second embodiment, the recess 11
Is surrounded by the convex portions 21 and 22 and the like, so that the rigidity of the heat insulator 10 can be secured, and vibration is hardly input.
55 can be made as large as possible, and a large amount of air flow can be introduced, so that the cooling efficiency of the exhaust manifold 1 can be greatly improved.

In the second embodiment, the cut-and-raised parts 52 and
55 is opened so that the air flow is concentrated at one point on the exhaust manifold 1, so that it is effective when a large amount of outside air is to be locally introduced.

[0025]

As described above, according to the present invention, a heat insulator that covers the outer surface of an exhaust manifold of an internal combustion engine with a gap between the outer surface and the outer surface protrudes toward the outer surface. Providing a cut-and-raised structure, providing a rising surface that rises smoothly adjacent to and facing the opening that is opened by the cut-and-raised structure, and forming a surface that is continuous with the rising surface at a height equal to or greater than the protruding height of the cut and raised structure. Therefore, it is possible to increase the outside air introduction area while securing the rigidity of the heat insulator, and since the surface continuous to the cut and raised portion is configured to have a height equal to or greater than the protruding height of the cut and raised portion, the air flow is applied to the cut and raised portion. Is efficiently introduced, and the exhaust manifold can be cooled uniformly.

[Brief description of the drawings]

FIG. 1 is a front view of a heat insulator according to a first embodiment of the present invention;

FIG. 2 is a partial arrow view in the direction B in FIG.

FIG. 3 is a partial sectional view taken along the line AA in FIG. 1;

FIG. 4 is a partial cross-sectional view showing a second embodiment of the present invention at a position similar to FIG. 3;

[Explanation of symbols]

1 Exhaust Manifold 10 Heat Insulator 11 Concave 12 Cut and Raised 21 Convex 25 Side F Air Flow

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01N 7/14 F01N 7/10

Claims (1)

(57) [Claims] 1. A heat insulator for covering an outer surface of an exhaust manifold of an internal combustion engine with a gap between the exhaust manifold and a cut-and-raised portion protruding toward the outer surface, and an opening portion opened by the cut-and-raised portion. A heat insulator for an exhaust manifold of an internal combustion engine, characterized in that a rising surface is provided which rises smoothly and is adjacent to and opposed to the rising surface, and a surface continuous with the rising surface is formed to have a height equal to or greater than the protruding height of the cut and raised portion.