JPH0932545A - Heat insulator structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat insulator structure by which not only a stipulation of an examination standard is satisfied but also a noise level is reduced by reducing pronunciation by a standing wave between resonance and an exhaust pipe. SOLUTION: Two punching metals 11a and 11b are respectively molded in a semicylindrical shape, and an air layer 12 and a clearance 14 are arranged on respective under surfaces, and are superposed on each other, and are installed so as to cover an upper surface of an exhaust pipe 6 by using a fixing plate. Holes of the punching metals 11a and 11b are dislocated from each other, and are made invisible so as not to see through a exhaust pipe from the upper surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulator structure mounted on an exhaust pipe.

[0002]

2. Description of the Related Art The current examination standard for new type automobiles is that "a structure in which luggage or the like does not fall between the rear surface of the cab and the front of the cargo box or the upper surface of a high temperature part such as an exhaust pipe is not exposed" There are regulations.

FIG. 7 is a front plan view of a cab-over type truck, where 1 is a cab, 2 is a luggage box, 3 is a front wheel, and 4 is an snorkel for intake, which is arranged under the cab 1. An exhaust pipe 5 extends rearward from an engine (not shown). Therefore, immediately after the engine, the hot exhaust pipe 6 is exposed between the rear surface of the cab 1 and the front portion of the luggage box 2,
In order to satisfy the above-mentioned examination standard, the heat insulator 7 made of sheet metal was attached. The heat insulator 7 is mounted so as to cover substantially the upper half of the exhaust pipe 6, but is usually installed between the heat insulator 7 and the exhaust pipe 6 in order to prevent the heat insulator 7 from reaching a high temperature due to heat transfer. 1
A gap of about 0 to 15 mm is provided. Note that FIG. 8 is a side view showing a mounted state of the heat insulator 7, 8 is a frame, 9 is a flexible pipe, and 10 is a support material for supporting the exhaust pipe 5 to the frame 9.

[0004]

In the above-described conventional heat insulator structure, the mounting position of the heat insulator 7 is close to the engine and is in the severest condition in terms of vibration. Therefore, due to resonance of the heat insulator 7 and sounding due to a standing wave between the exhaust pipes, acceleration noise of +0.
A deterioration of about 1 to +1.0 dB (A) is recognized.
However, in the conventional sheet metal structure heat insulator,
Even if the rigidity was improved by increasing the plate thickness and adding ribs, there was sounding with the standing wave between the exhaust pipe and the deterioration of the noise level could not be prevented.

Therefore, the present invention provides a heat insulator structure which not only satisfies the requirements of the examination standard but also reduces the sound level due to the standing wave between the resonance and the exhaust pipe to lower the noise level. To aim.

[0006]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems and has a large number of holes in a heat insulator structure mounted so as to cover the upper surface of an exhaust pipe.
It is characterized in that a sheet of punching metal is formed into a semi-cylindrical shape, a gap is provided on each lower surface, and the two punching metals are superposed so as to be invisible so that the exhaust pipe cannot be seen from the upper surface. It is a heat insulator structure.

Further, the present invention is characterized in that the holes of the two punching metals are displaced from each other so as to be invisible, and the gap between the punching metals is an air layer. It is characterized in that the heat insulating material is covered with aluminum foil and interposed.

[0008]

According to the above-mentioned means of the present invention, the use of two punching metals each having a gap on the lower surface prevents the standing wave sound from being generated and prevents the noise due to the standing wave sound of the heat insulator. it can. In addition, the heat insulator can be made invisible by displacing the holes of the two punching metals or by interposing the heat insulating material coated with aluminum foil between the two punching metals. The upper surface of the can be prevented from being exposed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a heat insulator structure according to the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment, in which a heat insulator 11 in which two punching metals are superposed is attached to cover an upper surface of an exhaust pipe 6. The two punching metals 11a and 11b forming the heat insulator 11 are each formed into a semi-cylindrical shape having flange portions 11c and 11d at both ends, and an air layer 12 is provided between the punching metals 11a and 11b.
Is provided. Also, both punching metal 11a,
The holes 11b are arranged so as to be offset from each other as shown in FIG. 3, and have an invisible structure in which the exhaust pipe 6 cannot be seen from the upper surface through the two superposed sheets. The holes in the punching metals 11a and 11b have a diameter of 2 mm, for example.
A large number of those are staggered at a pitch of 5 mm.

To mount the heat insulator 11 on the exhaust pipe 6, the punching metals 11a, 11 are attached to the flange portions 13c, 13d of the fixed plates 13a, 13b.
The flange portions 11c and 11d of b are tightened together with bolts and nuts. At this time, although the fixing plates 13a and 13b having a relatively narrow width are tightly fixed by sandwiching the outer peripheral surface of the exhaust pipe 6, there is a conventional structure between the inner punching metal 11b of the heat insulator 11 and the exhaust pipe 6. There is also a gap 14 which provides an air layer to minimize heat transfer.

With the heat insulator structure having the above-described structure, the presence of the holes in the punching metals 11a and 11b and the presence of the air layer 12 eliminates the generation of a standing wave between the exhaust pipe and the heat insulator due to engine vibration, so that the heat insulator 11 is eliminated. It is possible to prevent noise caused by the standing wave sound of the structure. FIG. 6 shows the result of an experiment comparing the noise level with the heat insulator of the conventional structure. The structure of the first embodiment shown by the solid line is in all engine rotation speed regions compared to the conventional structure shown by the dashed line. A significant reduction in noise level is recognized.

Also, two punching metals 11a, 1
The exhaust pipe 6 is made invisible by shifting the hole of 1b to make it invisible.
The upper surface of the can be prevented from being exposed, and the requirements of the examination standard can be satisfied. It is easier to make holes of punching metal invisible when the diameter is smaller and the pitch is larger, and the prevention of standing waves is especially large unless the holes are extremely small or the number of holes is reduced. There is no difference.

FIGS. 4 and 5 show a second embodiment of the present invention, in which an aluminum foil coating heat insulating material layer (hereinafter referred to as aluminum coating heat insulating layer) 15 is interposed in the gap between the two punching metals 11a and 11b. Has been done. This aluminum coating heat insulation layer 15
Insulation material 16 thicker than the gap between punching metals is entirely covered with aluminum foil (hereinafter referred to as aluminum foil) 17. About 1.5 times thicker and wrapped with aluminum foil 17, two punching metals 11a, 1
It suffices to compress and insert between 1b. Further, the punching metal 11a located on the aluminum-coated heat insulating layer 15 is
Shift stoppers 18 for the aluminum-coated heat insulating layer 15 are provided at both ends of the semi-cylindrical shape.

The configuration of the second embodiment described above is also shown in FIG.
As indicated by a broken line in FIG. 3, noise caused by sounding due to a standing wave between the exhaust pipe and the heat insulator 11 can be reduced as compared with the conventional structure. Further, the presence of the aluminum-coated heat insulating layer 15 makes the heat insulator 11 invisible and prevents not only the falling matter of the solid matter but also the countermeasure against the falling matter of the liquid such as oil. Furthermore, thermal insulation 1
6 has two functions of the role of the aluminum foil 17 as a support and the improvement of heat insulation. The positions of the holes in the punching metals 11a and 11b may be displaced from each other as in the first embodiment, or may be aligned with each other.

[0016]

According to the above-described heat insulator structure of the present invention, in addition to providing the air layer and the gap,
Since the punching metal that does not generate the standing wave and has a large vibration damping effect is used, the sound level of the heat insulator can be eliminated by reducing the noise level.
The invisible structure in which the holes of the punching metal are displaced can prevent both solid matter from falling and the upper surface of the high temperature portion of the exhaust pipe from being exposed.

Further, if an aluminum-coated heat insulating layer is provided between two punching metals instead of an air layer, the noise level reduction effect is somewhat inferior, but the liquid drop can be prevented in addition to the solid matter. Occurs, and is also effective in improving the heat insulation performance.

[Brief description of drawings]

FIG. 1 is a perspective view showing a first embodiment of the present invention.

FIG. 2 is a view on arrow A in FIG.

FIG. 3 is a diagram showing an example of hole arrangement of punching metal in the plan view of FIG. 1.

FIG. 4 is an exploded perspective view showing a second embodiment of the present invention.

FIG. 5 is a cross-sectional view of essential parts of a second embodiment.

FIG. 6 is a diagram showing a relationship between an engine speed and a noise level in each of the structures of the first embodiment and the second embodiment of the related art.

FIG. 7 is a front plan view of a cab-over type truck.

FIG. 8 is a side view showing a conventional heat insulator structure and a mounting state thereof.

[Explanation of symbols]

1 Cab 2 Packing Box 5 Exhaust Pipe 6 Exhaust Pipe 7, 11 Heat Insulator 11a, 11b Punching Metal 11c, 11d Flange 12 Air Layer 14 Gap 15 Aluminum Foil Cover Insulation Layer (Aluminum Cover Insulation Layer) 16 Insulation 17 Aluminum Foil ( Aluminum foil)

Claims (3)

[Claims] 1. In a heat insulator structure which is mounted so as to cover an upper surface of an exhaust pipe, two punching metals having a large number of holes are formed into a semi-cylindrical shape, and a gap is provided on each lower surface, and exhaust is performed from the upper surface. A heat insulator structure in which the two punching metals are superposed and made invisible so that the tube cannot be seen through. 2. The heat insulator structure according to claim 1, wherein the holes of the two punching metals are displaced from each other to make them invisible, and the gap between the punching metals is an air layer. 3. The heat insulator structure according to claim 1, wherein a heat insulating material is covered with an aluminum foil and is interposed in a gap between the two punching metals.