JP5866145B2 - Heat shield cover for piping and manufacturing method thereof - Google Patents

Description

  The present invention relates to a heat insulating cover for covering and heat-insulating piping such as an exhaust pipe of an automobile, and a method for manufacturing the same.

  In general, the exhaust gas of an automobile engine is sent to a catalytic converter through an exhaust pipe, and is discharged from the muffler into the atmosphere after removing air pollutants by the catalytic converter. In the catalytic converter, it is desired that the exhaust gas temperature is high from the viewpoint of raising the temperature of the catalyst to the activation temperature in a short time, and in order to prevent the temperature of the exhaust gas from decreasing before reaching the catalytic converter, the exhaust pipe Insulation is performed. The same heat shielding is also performed in the pipe of the heat recovery mechanism that sends the exhaust gas to the intake side again in order to quickly warm up the engine.

  The heat insulation structure of the exhaust pipe is generally a double pipe structure in which an air layer is interposed between the exhaust pipe and the outer pipe, but the exhaust pipe is curved in a complicated manner to avoid various parts. Therefore, in Patent Document 1, for example, a metal wire is spirally wound around an exhaust pipe to form a spacer, and after fitting the outer pipe, the exhaust pipe and the outer pipe are bent together at a predetermined position. However, since both the exhaust pipe and the outer pipe are made of metal, a jig for bending is necessary, and even though the metal wire is wound, it is easy to buckle when bent greatly, and the heat shielding effect May not be sufficient.

  Further, the applicant of the present invention also previously described in Patent Document 2 is a flexible structure in which ring-shaped spacers are fixed to the outer peripheral surface of the curved exhaust pipe at an arbitrary interval, and a glass cloth is bonded to the inner surface of the metal foil. It is proposed to install an outer tube. However, the spacer must be fixed, and the temperature of the gas flowing through the exhaust pipe may be lowered due to the heat capacity of the spacer.

Japanese Patent Laid-Open No. 2002-228055 JP 2004-285849 A

  In view of such a background, an object of the present invention is to provide a heat insulating cover for piping that can be easily attached to a curved exhaust pipe and has an excellent heat insulating effect.

In order to achieve the above object, the present invention provides the following heat shield cover for piping and a method for manufacturing the same.
(1) An inorganic fiber which is attached to a pipe and has a plurality of openings penetrating in the direction perpendicular to the major axis direction of the pipe heat shield cover on the inner surface of the valley portion over the entire length of the bellows pipe made of metal foil. it by bonding a manufacturing mats, a heat shield that to form an air layer between the pipe the opening when wearing said bellows tube,
The heat insulating cover for piping, wherein the opening has an elliptical planar shape with a major axis portion along the major axis direction of the piping.
(2) The heat insulating cover for piping according to the above (1), wherein the opening ratio of the inorganic fiber mat is 25 to 85%.
(3) The heat insulating cover for piping according to the above (1) or (2), wherein the inorganic fiber mat is a glass fiber mat.
(4) The heat insulating cover for piping according to any one of (1) to (3), wherein the metal foil is a stainless steel foil.
(5) A plurality of openings are formed in the inorganic fiber mat formed into a flat plate shape so as to penetrate the thickness portion so that the long diameter portion has an elliptical planar shape along the longitudinal direction of the inorganic fiber mat. Process,
The inorganic fiber mat in which the opening is opened, a step of winding the core material,
Applying an adhesive to the outer peripheral surface of the inorganic fiber mat or the inner surface of the valley of the bellows tube made of metal foil;
Inserting the core material around which the inorganic fiber mat is wound into the metal foil bellows tube while the adhesive is uncured;
Curing the adhesive and bonding the outer peripheral surface of the inorganic fiber mat to the valley inner surface of the metal foil bellows tube;
After the adhesive has hardened, extracting only the core material;
The manufacturing method of the heat insulation cover for piping characterized by having.
(6) A plurality of openings are formed through the thickness portion of the inorganic fiber mat formed into a cylindrical shape so that the long diameter portion has an elliptical planar shape along the longitudinal direction of the inorganic fiber mat. Process,
The inorganic fiber mat in which the opening is opened, a step of externally fitted on the core material,
Applying an adhesive to the outer peripheral surface of the inorganic fiber mat or the inner surface of the valley of the bellows tube made of metal foil;
While the adhesive is uncured, a step of inserting a core material fitted with the inorganic fiber mat into the metal foil bellows tube;
Curing the adhesive and bonding the outer peripheral surface of the inorganic fiber mat to the valley inner surface of the metal foil bellows tube;
After the adhesive has hardened, extracting only the core material;
The manufacturing method of the heat insulation cover for piping characterized by having.

The heat insulating cover for piping according to the present invention is a joined body in which a bellows tube made of metal foil and an inorganic fiber mat having a plurality of openings are bonded to each other , so that it can be easily attached to a curved pipe. it can. Further, since the inorganic fiber mat functions as a spacer between the bellows tube and the pipe, it is not necessary to provide a separate spacer. Furthermore, the opening of the inorganic fiber mat becomes an air layer to achieve good heat insulation.

  Moreover, the method of manufacturing the heat insulation cover for piping is also simple, and it is excellent in productivity and can be manufactured at low cost.

It is sectional drawing which showed the thermal insulation cover for piping of this invention along the longitudinal direction. It is the figure which expanded and showed the A part of FIG. 1 in the state which attached the heat shield cover for piping to the exhaust pipe. Is a plan view showing a non-machine textile mat in the pipe for heat shield of the present invention. Is a plan view showing an unfavorable example of the opening of the non-machine fiber mat. It is a graph which shows the measurement result of (exit temperature / inlet temperature) ratio of the thermal insulation cover of an example and a comparative example.

  Hereinafter, the heat insulating cover for piping of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing the heat insulating cover for piping according to the present invention along its longitudinal direction, and FIG. 2 is an enlarged view of the portion A in FIG. It is. As illustrated, piping heat insulating cover, the valley inner surface 1a of the metal foil made bellows tube 1, in which the inorganic fiber mat 10 having a plurality of openings 11 is opened to penetrate through the thickness portion and contact wear is there.

  Examples of the material of the metal foil-made bellows tube 1 include aluminum foil and stainless steel foil, but stainless steel foil is preferable from the viewpoint of heat resistance. Also, considering the strength and ease of bending, the thickness is 100 to 300 μm, the distance between the top and the top of the bellows is 1.5 to 2.5 mm, and the height difference between the top and the valley is 2 to 3 mm. Is appropriate. With such a configuration, it is possible to provide a heat insulating cover for piping that can be bent and bend easily.

  As the inorganic fiber mat 10, a woven fabric of glass fiber or ceramic fiber, or a material obtained by depositing glass fiber or ceramic fiber by matting with a needle punch can be used. Among these, glass fiber is preferable because it is inexpensive and excellent in flexibility. Further, since the longer the fiber length, the easier it is to align in the plane direction, a glass fiber of 30 mm or more deposited and matted by a needle punch is preferable. Further, the roving and yarn are preferably in a weight ratio and the roving / yarn ratio is preferably 50/50 to 0/100, more preferably 20/80 to 40/60. As used herein, roving means a roving made by gathering fibers (a single fiber having a length at least 100 times the diameter) without twisting, and a yarn is one or more strands (a single fiber having no twist). Is a processed yarn obtained by twisting together a bundle.

  In order to form the opening 11 in the inorganic fiber mat 10, a plurality of inorganic fiber mats 10 can be stacked and processed at a time, and therefore a method using a punching press is simple and preferable.

  The inorganic fiber mat 10 may be formed in a cylindrical shape. In order to produce the cylindrical inorganic fiber mat 10, the inorganic fibers are deposited and matted with a needle punch, and the opening 11 is formed with a punching press, wound around a core material, and then an inorganic binder in water. There are methods such as dipping in a dispersion liquid in which the core material is dispersed and extracting the core material after drying. Bentonite is preferred as the inorganic binder. Further, as the amount of the inorganic binder impregnated increases, the inorganic fiber mat 10 becomes harder and the flexibility, which is a characteristic of the heat insulating cover for piping of the present invention, is impaired. The amount of impregnation is adjusted appropriately.

  The organic content contained in the inorganic fiber mat 10 is preferably 3% by mass or less, and more preferably 1% by mass or less, based on the total amount of the inorganic fiber mat. The organic component is mainly a binder used when processing into roving or yarn. The smaller the organic content, the more preferable it is because volatile gas is reduced when heat is applied after being incorporated in the pipe. Here, the organic component can be substituted by the ignition loss rate after heating at 700 ° C. for 30 minutes.

The density of the glass mat is appropriately 50 to 300 kg / m ³ in consideration of deformation and its own heat capacity, preferably 100 to 300 kg / m ³ , more preferably 150 to 250 kg / m ³ . This density adjustment can be adjusted by the basis weight of fibers to be deposited (weight per unit area) and the number of needle punch needles (number of punches per unit area). The number of needle punch needles may be 5 to 40 / cm ² , and preferably 20 to 40 / cm ² . As the number of needles increases, fine punching becomes possible when the opening 11 is formed.

  In addition, since the inorganic fiber mat 10 functions as a spacer, the metal foil bellows tube 1 may become the exhaust pipe 30 through the opening 11 if it is too thin. On the other hand, if it becomes too thick, the influence of its own heat capacity becomes large, and the heat shielding effect is lowered. Therefore, the mat thickness is suitably 0.5 to 10 mm, preferably 1 to 10 mm, more preferably 1 to 5 mm.

  The opening ratio, that is, the ratio of the total area of the opening to the area of the inorganic fiber mat 10 is preferably 25 to 85%, more preferably 50 to 80%, and further preferably 65 to 80%. As the aperture ratio increases, the air layer when mounted on the exhaust pipe 30 increases, and the contact area between the inorganic fiber mat 10 and the exhaust pipe 30 decreases, so that the influence of its own heat capacity is reduced. Will increase. However, as the aperture ratio increases, the cross of the inorganic fiber mat 10 (for example, 10b in FIG. 3A or 3B) formed between the openings 11 and 11 becomes thinner, and will be described later. In addition, there is a risk of deformation during the manufacture of the heat shield cover. Moreover, since each opening 11 becomes large, there exists a possibility that the metal foil bellows pipe 1 may bend and contact with the exhaust pipe 30.

The shape of apertures 11, since the charging property is improved, as shown in Figure 3, the major axis portion is an elliptical shape along the longitudinal direction.

  To manufacture the heat insulating cover for piping of the present invention, first, a metal foil bellows tube 1 is prepared, and an adhesive is applied to the valley inner surface 1a. The adhesive is preferably an inorganic adhesive from the viewpoint of generated gas after construction. Adhesive is not limited as long as it can bond metal and inorganic fiber, ceramic system such as alumina, silica, zirconia, mullite, silicon carbide, water glass system such as sodium silicate and sodium silicate, cement using hydration reaction, etc. Can be used. Meanwhile, an inorganic fiber mat 10 having an opening 11 is wound around a cylindrical or columnar core so that the edges 10a in the longitudinal direction come into contact with each other. And while the adhesive is uncured, the inorganic fiber mat 10 is inserted into the metal foil bellows tube 1 together with the core material, and the inorganic fiber mat 10 and the valley inner surface 1a of the metal bellows tube 1 are connected. After the adhesive is cured in the contact state, only the core material is extracted.

  Further, instead of applying an adhesive to the valley inner surface 1a of the metal foil bellows tube 1, an adhesive is applied to the outer peripheral surface of the inorganic fiber mat 10 wound around the core material, and the inorganic fiber mat 10 together with the core material is applied. May be inserted into the metal foil bellows tube 1.

  The same applies to the case where a cylindrical inorganic fiber mat is used, and the outer periphery of the cylindrical inorganic fiber mat applied to the valley inner surface 1a of the metal foil bellows tube 1 or externally fitted to the core material. An adhesive is applied to the surface, the core material is inserted into the metal foil bellows tube 1, and after the adhesive is cured, only the core material is extracted.

In view of such a manufacturing method, FIG. 4 (A), the rectangular opening 11 and as shown (C), the inorganic fiber mat opening the opening 11 of the triangle, as shown in (B) in 10, thin lattice crosspiece 10b between the openings, in contact with the troughs the inner surface 1a grating bars 10b upon insertion of the metal foil made bellows tube 1 is Ru danger of deforming.

  The heat insulating cover for piping of the present invention is effective for heat insulation of the piping, but as shown in the examples described later, the temperature of the fluid flowing through the piping is particularly remarkable in the range of 300 to 600 ° C. Show. Therefore, application to an exhaust pipe disposed in the vicinity of an automobile engine is preferable.

Furthermore, according to the heat insulating cover for piping of the present invention, it is expected to realize early warm-up of the automobile. That is, since the heat capacity is lower than that of the conventional double pipe structure, it is difficult to take heat of the exhaust pipe immediately after starting the engine, and it is expected that the warm-up time is shortened.

  Moreover, the heat insulating cover for piping of the present invention is bendable, easily bent, and can be easily attached to bent piping. Furthermore, when it is attached to such a bent pipe, contact between the pipe and the metal foil bellows pipe is hindered by the inorganic fiber mat at the bent portion of the pipe. As a result, it is avoided that the heat-spot is formed due to contact between the pipe and the outer pipe at the bent portion, which has been a concern in the conventional double-pipe structure, and a heat spot is formed.

  The present invention will be further described below with reference to examples, but the present invention is not limited thereto.

Example 1
After glass fiber is deposited using an air stream, it is matted by a needle punch, and this mat is molded with bentonite as a binder by an impregnation molding method to produce a glass fiber mat. The aperture ratio was 75%. The glass fiber mat had a thickness of 2.3 mm and a density of 190 kg / m ³ .

  This glass fiber mat was wound around a SUS304 straight pipe having an outer diameter of 38.1 mm, a wall thickness of 0.8 mm, and a length of 500 mm, and a bellows-like foil made of SUS429 was adhered to the outer peripheral surface thereof to obtain a measurement sample.

(Example 2)
A measurement sample was prepared in the same manner as in Example 1 except that the opening ratio of the glass fiber mat was 50%.

(Example 3)
A measurement sample was prepared in the same manner as in Example 1 except that the opening ratio of the glass fiber mat was 25%.

(Comparative Example 1)
A measurement sample was prepared in the same manner as in Example 1 except that a glass fiber mat was not used (opening ratio: 100%).

(Evaluation of thermal insulation properties)
Air having a temperature of about 500 ° C. and a mass flow rate of about 5 g / s was passed through the straight tube of the produced measurement sample for 100 seconds, and the temperatures of the air inlet and outlet were measured. The measured inlet temperature and outlet temperature were each corrected by subtracting the room temperature in order to eliminate fine influences from the measurement environment. And in order to evaluate the heat insulation characteristic of a measurement sample, the time change of (exit temperature / inlet temperature) ratio was calculated | required.

  The above measurement results are shown in FIG. 5, and since heat energy is consumed for temperature rise of the inner pipe immediately after the start of heating, the pipe temperature rises with time and heat energy loss is reduced. As a result, the (outlet temperature / inlet temperature) ratio increases. However, since the measurement sample of each example has a large energy loss by the heat capacity of the heat insulating material immediately after the start of heating, the (exit temperature / inlet temperature) ratio is lower than that of the measurement sample of the comparative example. However, the measurement sample of each example shows a higher (exit temperature / inlet temperature) ratio than the measurement sample of the comparative example in only about 50 seconds after the start of heating, and is a shield better than the conventional double pipe. Thermal performance is obtained. Moreover, Example 2 with an aperture ratio of 50% and Example 3 with an aperture ratio of 25% are superior in heat shielding performance compared to Example 1 with an aperture ratio of 75%.

1 Metal foil bellows tube 10 Inorganic fiber mat 11 Opening

Claims (6)

An inorganic fiber mat having a plurality of openings penetrating in a direction perpendicular to the major axis direction of the heat insulating cover for piping is formed on the inner surface of the valley portion over the entire length of the bellows tube made of metal foil. bonded becomes, the a heat shield that to form an air layer between the pipe the opening when wearing said bellows tube,
The heat insulating cover for piping, wherein the opening has an elliptical planar shape with a major axis portion along the major axis direction of the piping.   2. The heat insulating cover for piping according to claim 1, wherein an opening ratio of the inorganic fiber mat is 25 to 85%.   The heat insulating cover for piping according to claim 1 or 2, wherein the inorganic fiber mat is a glass fiber mat.   The heat insulating cover for piping according to any one of claims 1 to 3, wherein the metal foil is a stainless steel foil. Forming a plurality of openings through the thickness portion so that the long-diameter portion of the inorganic fiber mat formed into a flat plate has an elliptical planar shape along the longitudinal direction of the inorganic fiber mat ;
The inorganic fiber mat in which the opening is opened, a step of winding the core material,
Applying an adhesive to the outer peripheral surface of the inorganic fiber mat or the inner surface of the valley of the bellows tube made of metal foil;
Inserting the core material around which the inorganic fiber mat is wound into the metal foil bellows tube while the adhesive is uncured;
Curing the adhesive and bonding the outer peripheral surface of the inorganic fiber mat to the valley inner surface of the metal foil bellows tube;
After the adhesive has hardened, extracting only the core material;
The manufacturing method of the heat insulation cover for piping characterized by having. A step of forming a plurality of openings through the thickness portion so that the long-diameter portion has an elliptical planar shape along the longitudinal direction of the inorganic fiber mat ;
The inorganic fiber mat in which the opening is opened, a step of externally fitted on the core material,
Applying an adhesive to the outer peripheral surface of the inorganic fiber mat or the inner surface of the valley of the bellows tube made of metal foil;
While the adhesive is uncured, a step of inserting a core material fitted with the inorganic fiber mat into the metal foil bellows tube;
Curing the adhesive and bonding the outer peripheral surface of the inorganic fiber mat to the valley inner surface of the metal foil bellows tube;
After the adhesive has hardened, extracting only the core material;
The manufacturing method of the heat insulation cover for piping characterized by having.

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