JPS60139996A - Heat-insulating double pipe and intermediate material thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a heat-insulating double pipe and its intermediate material, and the present invention relates to a high-temperature heat-insulating double pipe and its intermediate material that has higher heat insulation, sound reduction, or sound insulation properties than conventional ones. It is related to materials.

(Technical background) Conventionally, insulated double pipes were developed as automobile exhaust pipes, and were thought to be widely used due to their simple shape and function. However, as an intermediate material, there is currently no material that has all of the following properties: heat resistance, heat insulation strength, sound insulation, and sound absorption, and the current situation is that only some of these functions are satisfied. That is, hollow double pipes and glass fiber double pipes are used for diesel trucks, and these double pipes have a small clearance of 02 to 06 pus.

Therefore, most of them have a low degree of insulation, and glass fibers are currently used to prevent abnormal noise caused by contact between the inner tube and the outer tube, which is a structural problem.

In addition to diesel trucks, in the field of private automobiles,
'F' double pipes are not widely used, and most of them are insulated with one type of protector. The main purpose of this method is heat insulation, and it is especially used to regulate the temperature of road surfaces. In other words, when driving at high speeds or stopping or parking after continuous driving, the temperature from the surface of the pipe to the road surface is high.

This is being implemented as a countermeasure against concerns that if there is highly flammable material such as dry grass on the road surface, it could cause a fire. Generally, a glass mat insulation material is set around the exhaust pipe on the road side, and is secured with a protector casing. The disadvantages of this method are that the protector is fastened with bolts or nuts, the shape of the exhaust pipe is complicated, so the protector becomes large and requires a lot of space for assembly, and when the car is running, the protector cannot be fastened with bolts or nuts. An example of this is Kokichi, which produces wind noise due to the protruding parts.

Under these circumstances, the use of double pipes, especially for automobile exhaust pipes, has been considered, but a suitable intermediate material has not yet been found. This is in the case of a passenger train.

Most vehicles are equipped with gasoline engines, and the temperature of the exhaust gas is becoming higher, especially due to the adoption of catalysts and superchargers to obtain high output due to recent exhaust gas regulations. Therefore, the intermediate material is required to have not only heat insulation but also heat resistance, and furthermore, due to noise regulation issues, it is also required to have sound-deadening and sound-insulating properties. Vehicles equipped with diesel engines have particularly high requirements regarding sound. In addition, in addition to the performance of double-walled pipes, there are many other issues when using double-walled pipes in passenger cars, such as the strength required in intermediate materials during manufacturing and processing, and the wear due to thermal distortion that occurs internally due to the complicated shape of the curved pipe. We have to solve the problems.

(Outline/Structure of the Invention) The present inventors have investigated these problems one by one and have repeatedly conducted experiments using a large number of materials. As a result, the present inventors have developed the high-temperature insulating double pipe of the present invention and its intermediate material. It was a success.

That is, for use in passenger cars, heat resistance must be considered first. This is because the temperature of the exhaust gas reaches about 800°C. High thermal insulation and sound insulation or sound absorption properties are also required. The form of material that meets these conditions is fibrous.

Heat-resistant materials include ceramic fibers, silica fibers, and crystalline fibers, and in combination, glass fibers and organic fibers can also be used as long as they have heat resistance. However, aggregates of fiber materials are generally considered to have a weak strength, and are particularly fragile when it comes to abrasion. This tends to become more severe as the fiber material becomes more heat resistant. There are products that have undergone special processing to make these materials high in density and strength.
The high cost is a major factor that makes it difficult to use at present.

Therefore, the present inventors have discovered that these heat-resistant fibers can be used as an excellent intermediate material for joining metallic materials in order to solve the problem of strength by using inexpensive sheet-like materials. However, it is difficult to bring out durability using only metallic materials. In particular, if it is not made of a heat-resistant metal, it will fall apart due to heat deterioration, and if it is not bonded to the fiber sheet, it will lack the ability to press down the inorganic fibers, causing the inorganic fibers to scatter or become uneven. Damage to the intermediate material due to bending, such as tearing, is protected by a metallic wire mesh or sheet, or avoided by sliding of the metal on the surface. Furthermore, it is double-pipe.

Due to the difference in the amount of thermal expansion due to the temperature difference between the inner and outer tubes in the curved tube section, a phenomenon of wear occurs due to friction caused by repeated heating and cooling. This is also because the presence of a metallic wire mesh or sheet on the surface prevents abrasion from directly reaching the fiber material, and even if it does, it does not progress any further6.

Such a metal wire mesh or sheet may be attached to an inorganic fiber material, or may be joined by sewing or binding. In addition, the fiber material has a form that allows it to easily exhibit the heat insulation and sound absorption properties that are the effects of the double pipe as an intermediate material. In terms of heat insulation and strength, it is desirable that the bulk density of the sheet-like fibrous material be higher.

If the bulk density is set to high by compression or the like, the fibers will be damaged. Experimentally, I would like to state that 02 to 0.4 U/d (is the ideal state. Of course.

It is possible to use it as an intermediate material with less or more than this.

Materials that can be used in such conditions are preferably metal sheets or wire mesh, and stainless steel is considered to be the most suitable material. But also other metals.

For example, iron-chrome wire, other heat-resistant steels, and depending on the temperature conditions, copper, brass, aluminum, etc. can also be used.

Also, inorganic fiber sheet material C, ceramic fiber, silica fiber, high heat-resistant glass fiber.

Depending on the temperature, highly heat-resistant organic fibers can also be used.

The metal sheet or wire mesh and the inorganic fiber sheet can be joined using an adhesive or mechanically, that is, by sewing or tying.

The intermediate material for double pipes thus obtained has both high heat insulation and sound dampening properties, and is a material that can be widely used.

(Example〕 Examples will be described below.

Example 1 A ceramic fiber blanket having a bulk specific gravity of 020 and a thickness of 6 m was cut into a width of 178 mm, and a stockinette knitted wire mesh of 5 US 304 wire diameter 02 frost was used as an intermediate material for wrapping. The sheet and the wire mesh were joined by folding in the ends of the wire mesh so that the wire mesh was set with one part of the sheet. This sheet was wrapped around a pipe with an inner diameter of 45 ynmφ and a thickness of 1 cylinder, and the outer tube was formed while narrowing to 57 φ to make a double pipe. The clearance at this time was 6 teachers. This double pipe was bent by 25 ORt in the right angle direction using a steel pipe bending device to make a double pipe pipe for a test. Further, a test piece of a double-pipe pipe was similarly prepared by pasting a 20 μm stainless steel foil on one side of the blanket so that the stainless steel foil was on the inner tube side.

After bending this tube, it was disassembled and damage caused by the bending of the intermediate material was confirmed. Clearance is 6mm, maximum at curved pipe part is 3mm
Although the pieces had been compressed to a certain degree, no parts were found where they had been torn off or crushed into powder.

Example 2 Ceramic fiber blankets with a bulk specific gravity of 0.2° and a thickness of 6 mm and bulk specific gravity of 0.16 mm and a silica fiber mat with a bulk specific gravity of 0.10 and a thickness of 10 mm were used in Example 1.
In the same manner as above, a double pipe was created by wrapping it in wire mesh and sewing and joining it with stainless steel yarn.

The clearance of each double tube was 4.5 wn.

Using this sample, the inlet and outlet temperatures were measured by passing gas at 800°C and are shown in the table below. As a comparative example, the case of a hollow double pipe is shown.

Example 3 Using the sample prepared in Example 2, gas at 800° C. and air at room temperature were alternately flowed at 3 minute intervals.

After 600 cycles of vibration using a vibrator with a frequency of 20 Hz, the tube was disassembled and the wear of the intermediate material was investigated.The results are shown in the table below. As a comparative example, a ceramic fiber blanket with a bulk specific gravity of 02 and a thickness of 6 is shown.

Patent applicant agent Patent Attorney Tomoyuki Yafuki (1 other person)

Claims (5)

[Claims] (1) An insulated double pipe made by filling an intermediate material between the inner tube and the outer tube, the surface of which is a sheet-like material mainly made of inorganic fibers [this is a heat-resistant metal sheet material or wire mesh covered and bonded] . (2) An intermediate material for heat-insulating double pipes, which is formed by covering the surface of a sheet-like material mainly made of inorganic fibers with a heat-resistant metal sheet-like material or wire mesh. (3) The heat insulation according to claim 2, characterized in that the heat-resistant metal sheet or wire mesh is coated and bonded to the surface of a sheet-like material mainly composed of inorganic fibers via an adhesive. Intermediate material for double pipes. (4) An intermediate for a heat-insulating double pipe according to claim 2 or 3, wherein the heat-resistant metal sheet or wire mesh is sewn or bound with metal yarn, wire, or wire mesh. Material. (5) The sheet-like material mainly composed of inorganic fibers is ceramic fiber, silica fiber, heat-resistant glass fiber,
The intermediate material for a heat-insulating double pipe according to any one of claims 2 to 4, characterized in that the intermediate material is one or more types of heat-resistant organic fibers.