JPS63154815A - Exhaust system equipment - Google Patents

Abstract

PURPOSE:To aim at making improvements in heat-impact resistance, vibro- resistance and distortion proof, by forming a heat insulating layer of exhaust system equipment with insulant powder and inorganic fiber. CONSTITUTION:A heat insulating layer to be formed in an inner surface of exhaust system equipment is made up of mixing inorganic fiber such as glass fiber or the like in insulant powder of hollow ceramic grains or the like. In this connection, the inorganic fiber may be laminated on the top where the insulant powder is stuck to an equipment inner surface. With this constitution, heat-impact resistance, vibro-resistance or the like are improved together with heat resistance and refractoriness and, what is more, separation of the heat insulating layer is preventable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to exhaust system equipment with excellent heat insulation and fire resistance suitable for use in internal combustion engine parts of automobiles such as exhaust manifolds.

[Prior Art 1] Exhaust system equipment of an internal combustion engine, particularly the exhaust manifold, is exposed to high-temperature, high-pressure combustion gas discharged from the cylinders of the engine, and therefore is desired to have high heat insulation properties and fire resistance. In particular, in recent years there has been a trend to increase the temperature of engine exhaust gas in order to improve engine efficiency, so it has become important to reduce heat loss in exhaust system equipment such as exhaust manifolds.

JP-A-58-51214 discloses exhaust gas system equipment for internal combustion engines, such as an exhaust manifold, whose inner surface is coated with a fire-resistant and heat-insulating coating. This exhaust gas equipment for internal combustion engines is
A coating layer of an amorphous refractory made of a mixture of refractory raw material particles and an inorganic binder is formed on the inner surface of the gold vessel body in contact with high-temperature exhaust gas.

Furthermore, Japanese Patent Application Laid-Open No. 58-99180 discloses a method of applying a fire-resistant and heat-insulating coating to the inner surface of exhaust gas system equipment for an internal combustion engine, such as an exhaust manifold. In this method, a heat-resistant coating layer is formed by depositing a slurry made of a mixture of refractory raw material particles, an inorganic binder, and a frit on the inner surface of a metal a device body that is in contact with high-temperature exhaust gas, and then the heat-resistant coating layer is While it is in a wet state, refractory insulation material particles are attached to the surface thereof to form a refractory insulation layer, and then the heat resistant coating layer is solidified, and refractory raw material particles and an inorganic binder are applied to the surface of the refractory insulation layer. A heat-resistant coating layer is formed by adhering a slurry made of a mixture of The required layers are formed by sequentially repeating heat-resistant coating layers made of the same material. By this method, a coating is formed in which the three layers of the heat-resistant coating layer, the fire-resistant heat insulating layer, and the heat-resistant coating layer are integrated and laminated.

Furthermore, JP-A No. 61-163282 discloses that an inorganic binder solution is applied to the inner surface of the exhaust system equipment through which high-temperature exhaust gas passes, and a fireproof insulation material powder is immediately attached to the layer of the nitrogen-free binder solution, followed by heat treatment. A fireproof heat insulating layer is formed by carrying out the first step including drying and solidifying steps at least once, and then an inorganic binder solution is applied to the surface of the fireproof heat insulating layer, and immediately the inorganic binder solution is applied to the surface of the fireproof heat insulating layer. By performing the second step at least once, which includes the step of attaching the human-resistance powder to the layer and drying and solidifying it by heat treatment, 't! Disclosed is a method for manufacturing exhaust system equipment characterized by forming 4* layers. This method does not use refractory insulation powder or a slurry of refractory material powder and inorganic binder solution, but rather adheres these powders to the coated layer of inorganic binder solution, so it is more effective than the former two methods. Heat treatment produces a fire-resistant and heat-insulating coating that is resistant to cracking and peeling.

[Problems to be Solved by the Invention] However, even with the fire-resistant and heat-insulating coating obtained by the method of JP-A No. 61-163282, thermal shock, vibration, and distortion due to high-temperature exhaust gas occur after long-term use. It has been found that problems such as cracks in the coating and peeling from the inner surface of exhaust system equipment occur due to such factors. Therefore, an object of the present invention is to provide an exhaust system device having a ceramic coating layer that has excellent heat insulation and fire resistance, and does not crack or peel even after long-term use.

[Means for Solving the Problems 1] In view of the above objectives, as a result of intensive research, the present inventors have found that by incorporating inorganic fibers in addition to heat insulating material powder into the heat insulating layer, thermal shock resistance can be achieved without impairing heat resistance. The inventors have discovered that vibration resistance and distortion resistance can be improved, and have come up with the present invention.

That is, the exhaust system equipment of the present invention has a heat insulating layer on the inner surface,
The heat insulating layer is characterized in that it is made of heat insulating powder and Muboga fiber. The inorganic fibers may be mixed with the heat insulating powder or may be laminated as separate layers. Further, a fire-resistant layer may be provided on the heat-insulating layer, and the fire-resistant layer may similarly contain inorganic fibers or ceramic fibers having better fire resistance.

The heat insulating layer formed on the inner surface of the exhaust system equipment of the present invention will be described in detail.

The heat insulating material powder constituting the heat insulating layer is preferably hollow ceramic particles with excellent heat insulating properties, and specifically, R-type heat insulating materials such as glass balloons, foamed silica, and perlite can be used. The particle size of the powder is 10-500μ
A range of m is appropriate. If it is smaller than 10 μm, there is a high risk of cracking or peeling due to shrinkage, and if it is larger than 500 μm, it will be difficult to form a smooth film layer. A more preferred particle size range is 20 to 200 microns. These heat insulating powders generally have a heat resistance of 1000°C or higher.

Examples of inorganic fibers that can be used in the heat insulating layer include glass fibers, carbonaceous fibers, mullite fibers, alumina fibers, zirconia fibers, and silicon carbide fibers.

Inorganic fibers generally have a diameter of 1 to 8 μm and a length of 0.
．． It is in the range of 5 to 10II11. If the diameter is less than 1 μm or the length is less than 0.5 mg, cracks due to shrinkage may occur.
Peeling easily occurs, and if the diameter is larger than 8 μm or the length is longer than 10 ruts, it is difficult to form a smooth coating layer. The preferred fiber diameter is 2 to 4 μm and the length is 1 to 6 ytn. These inorganic fibers generally have a heat resistance of 900°C or higher.

In the present invention, the inorganic binders used to impart adhesiveness to the heat insulating layer include silicate binders such as sodium silicate, potassium silicate, lithium silicate, monobasic aluminum phosphate, monobasic calcium phosphate, monobasic phosphate, etc. Phosphoric acid binders such as magnesium, bound sodium phosphate, phosphoric acid, sol binders such as colloidal silica, colloidal alumina, colloidal zirconia, and ethyl silicate are suitable.

The binder is used in the form of an aqueous solution, and its concentration is between 20 and 6
0% by weight is preferred. If it is less than 20% by weight, the adhesive strength is low and it is easy to peel off. Moreover, if the content is higher than 60% by weight, the coating operation becomes difficult. More preferably, it is 25 to 55% by weight.

Appropriate amounts of curing agents can also be added to the binder solution. Although the curing agent differs depending on the type of binder, any known curing agent can be used. For example, silicate binders include sodium silicide, calcined aluminum phosphate, dicalcium silicate, tannic acid gas, and the like. In addition, for aluminum phosphate, basic oxides such as magnesia and lime,
Examples include calcium aluminate and ammonium fluoride.

A fire-resistant layer may be formed on the heat-resistant layer if necessary. Chamotte, heat-resistant glass (Pyrex glass), fused silica, cordierite, mullite, alumina, zircon, zirconia, etc. can be used as the refractory material powder constituting the refractory layer, but zirconia in particular has low thermal conductivity. preferable. The average particle size of refractory powder is generally 1
It is in the range of 0 to 500 μm. If the particle diameter is smaller than 10 μm, agglomeration between particles tends to occur, making it difficult to form a smooth coating layer, and easily shrinking due to the influence of high heat. 500 again
If it is larger than μm, it is difficult to form a smooth film. The preferred particle size range is 20-200 μm.

Ceramic fibers may also be added to the refractory layer, but the ceramic fibers preferably have a heat resistance of 1200° C. or higher. Specifically, mullite fiber,
There are alumina fibers, zirconia fibers, carbonaceous fibers, etc.

The diameter and length of these fibers may be the same as those of the above-mentioned inorganic fibers.

Incidentally, the free quality binder for the fire-resistant layer may be the same as that for the above-mentioned heat-resistant layer.

Next, l! of the exhaust system cupboard of the present invention! The manufacturing procedure of the yi thermal layer and the fireproof layer will be explained.

First, an inorganic binder solution is applied to the inner surface of the exhaust system equipment by spraying or the like. A heat insulating material powder is applied to the resulting uniformly thick inorganic binder solution layer.

Although any method can be used as long as the heat insulating material powder is uniformly adhered to the solution layer, a particularly preferred method is a method in which the heat insulating material powder is sprinkled on the inorganic binder solution layer. Alternatively, the inorganic binder solution can be removed by filling the inside of the exhaust system equipment coated with insulation powder and removing only the unattached insulation powder after the solution has sufficiently penetrated the insulation powder. Another method is to form a layer of impregnated insulation powder.

In either method, air blowing is preferably performed to completely remove unimpregnated insulation powder. The thickness of the heat insulating layer thus obtained depends on the concentration and thickness of the inorganic binder solution, but is generally 100 to 15
It is about 00μ skin.

Next, perform humidification as necessary. Humidification regimen is 50-80
℃ temperature, 40-80% relative temperature 30-120
This is done by holding it for a minute. As a result, the heat insulating layer is solidified and held by the inorganic binder solution, thereby drying.

In forming the heat insulating layer, inorganic fibers are contained in the heat insulating material powder, and the inorganic fibers may be mixed in or the inorganic fiber layer may be a layer. Note that when inorganic fibers are laminated, the same procedure as above is used.

In order for the heat insulating layer to have sufficient heat insulating properties, at least 1.
It is necessary to have a thickness of 5iJ1 or more, and for that purpose, the above steps may be repeated multiple times. In that case, it is efficient and preferable to apply the inorganic binder solution without drying after curing and dry after a heat insulating layer of desired thickness is formed.

After drying, heat-treat the heat insulating layer. The heat treatment is performed by gradually heating to about 775°C and holding at that temperature for 30 to 60 minutes.

Next, if necessary, a fireproof layer is formed on the heat insulating layer.

The method for manufacturing the refractory layer may be exactly the same as the method for manufacturing the heat insulating layer, except for using the above refractory material powder and ceramic fiber. Since the thickness of the refractory layer is preferably 0.5 seconds or more, the refractory layer forming step may be repeated multiple times. In addition, although heat treatment is performed throughout the process, heat treatment is not performed on the insulation layer forming paper.
It may be carried out all at once after the formation of the refractory layer.

[Examples] The present invention will be explained in more detail by the following examples.
The present invention is not limited thereto.

Example 1 As a first step, a sodium silicate aqueous solution with a silica ratio of 2.9 and a concentration of 36% by weight was applied to the inner surface of a manifold made of spheroidal graphite cast FQ having an oxide film that had been previously degreased with an alkaline solution of pH 10 to 11. 10% by weight of calcined aluminum phosphate (Hoechst VH, B hardener) was added as a hardening agent and applied by spraying. Immediately, Shirasu balloons (alumina-siliceous hollow spherical particles) having a bulk specific gravity of 0.2 and a particle size of 44 to 150 μm were sprinkled as a heat insulating material powder.

After applying the above inorganic binder solution again by spraying, a ceramic fiber with a diameter of 2 to 4 μm and a length of 2
~4 Dark alumina fiber was sprayed.

Then, it was kept at room temperature for 1 hour, and then heated to 50°C for 1 hour.
Hold for 1 hour, further heat to 100℃ and hold for 1 hour,
Rv! ! The temperature was raised to 300°C and held for 1 hour. This heat treatment completely solidified the heat insulating layer. By repeating this process, a heat insulating layer with a thickness of 3111 #I was obtained.

The proportion of ceramic fiber in the insulation layer is approximately 25% by weight.
Met.

As a second step, the same inorganic binder solution as above is applied on the heat insulating layer by spraying, and the particle size is 44~
Stabilized zirconia particles of 150 μm were sprinkled. After laminating the desired zirconia particle layers, the same heat treatment as above was performed to form a fireproof layer with a thickness of 0.5 degrees.

The following tests were conducted on the manifold obtained in this example, and the results were good.

(1) Heat resistance test Continuously blow hot air at 850°C into the inside of the manifold for 100°C.
After blowing air for a time, it was cooled to room temperature, but no damage, cracks, or peeling of the coating layer was observed.

(2) F'! I, III Impact Test A cycle of blowing hot air at 850° C. into the manifold for 30 minutes and then allowing it to cool to 100° C. was repeated 150 times, but no damage, cracks, or peeling of the coating layer was observed.

(3) Continuously blow hot air at i, ooo ℃ into the inside of the insulation test manifold for 30
After feeding for 1 minute, the temperature of the outside surface of the manifold without coating was 800%.
˜850° C., but the outer surface temperature of the manifold of the present invention was 550-600″C, and was found to have excellent heat insulation properties.

(4) Vibration test Although the product was continuously vibrated for 200 hours under the conditions of 20G x 280 Hz, no damage, cracks, or peeling of the coating layer was observed.

(5) Constant strain test The test was repeated 100 times by fixing one end of the manifold and adding a cart in the vertical direction to the other end, giving a strain of ±2 degrees, but no damage, cracks, or peeling of the coating layer was observed. I couldn't.

(6) Furthermore, even when the above tests were conducted in combination on a single manifold, no damage, cracking, or peeling of the coating layer was observed.

Example 2 As a first step, the same non-[T binder solution as in Example 1] was applied as a spray onto the inner surface of a spheroidal graphite cast iron manifold having an oxide film that had been previously degreased with an alkaline solution with a pH of 10 to 11. . Bulk specific gravity is 0 immediately as insulation powder
．． 2) Alumina-siliceous hollow particles (shirasu balloons) having a particle size of 44 to 150 μm were scattered and adhered, and dried.

After applying the atomized inorganic binder solution again, mullite fibers having a diameter of 2 to 4 μm and a length of 2 to 4 pieces were sprinkled. A heat insulating layer having a thickness of 3 ratr was obtained by layering the above heat insulating powder layer and one layer of mullite fiber as desired. The heat treatment of the heat insulating layer was performed at 180° C. for 3 hours. The proportion of mullite fibers in the heat insulating layer was about 30% by weight.

The obtained heat insulating manifold was subjected to the same test as in Example 1, but no damage, cracks or peeling of the coating layer was observed.

As a first step, the same inorganic binder solution as in Example 1 was applied in the form of a spray onto the inner surface of a manifold made of spherical graphite iron having an oxide film that had been previously degreased with an alkaline solution having a pH of 10 to 11. Bulk specific gravity is 0 immediately as insulation powder
．． 2) Alumina-siliceous hollow particles (shirasu balloons) having a particle size of 44 to 150 μm were scattered and adhered, and dried.

After applying the atomized atomized binder solution again, mullite fibers having a diameter of 2 to 4 μm and a length of 2 to 4 μm were sprinkled. The above-mentioned heat insulating powder layer and one layer of mullite fiber were combined to form a heat insulating layer of three thicknesses at the desired thickness of 11ffffL. This was heat treated at 180°C for 3 hours. The proportion of mullite fibers in the heat insulating layer was about 30% by weight.

As a second step, the same inorganic binder solution as above is applied on top of the above heat insulating layer, and the diameter is 2 to 4 μm and the length is 2 to 4 μm.
4M zirconia fiber was sprayed. After a desired layer of this zirconia fiber was laminated, the same heat treatment as above was performed to form a refractory layer with a thickness of 0.5 degrees.

The obtained heat insulating manifold was subjected to the same test as in Example 1, but no damage, cracks or peeling of the coating layer was observed.

Example 4 As a first step, the same n-free binder solution as in Example 1 was sprayed onto the inner surface of a spheroidal graphite cast iron manifold having an oxide film that had been previously degreased with an alkaline solution of P Hi o to 11. Coated. A mixture of alumina-siliceous hollow particles (shirasu balloons) with a bulk specific gravity of 0.2) particle size of 44 to 150 μm immediately as a heat insulating material powder and milled fibers with a diameter of 2 to 4 μm and a length of 2 to 10 μm as Mujiga fiber. (weight ratio 25:75) was applied to the coating film of the inorganic 11 binder solution and then dried. Desired layers of the mixture of the above heat insulating material powder and milled fiber were laminated to form heat insulating layers of three thicknesses.

This was heat treated at 180°C for 3 hours.

The same test as in Example 1 was conducted on the blued insulation manifold, but no damage, cracking, or peeling of the coating layer was observed.

X1■1 As a first step, the same inorganic binder solution as in Example 1 was applied in the form of a spray onto the inner surface of a spheroidal graphite cast iron manifold having an oxide film that had been previously degreased with an alkaline solution having a pH of 10 to 11. Bulk specific gravity is 0 immediately as insulation powder
．． 2) Feed a mixture of alumina-siliceous hollow particles (shirasu balloon) with a particle size of 44 to 150 μm and milled fibers with a diameter of 2 to 4 μm and a length of 2 to 10 μm (weighting: 25 near 5) as R-free fibers. Then, the coated film of Mubetsu binder solution was applied and dried. Desired layers of the mixture of the above heat insulating material powder and milled fiber were laminated to obtain a heat insulating layer with a thickness of 3 mm. This was heat treated at 180°C for 3 hours.

As a second step, the same aporous binder solution as above was applied onto the heat insulating layer, and stabilized zirconia particles having a particle size of 44 to 150 μm were further sprinkled thereon.

After laminating the desired zirconia particle layers, the same heat treatment as above was performed to form a fireproof layer with a thickness of 0.5 mm.

The same test as in Example 1 was conducted on the blued insulation manifold, but no damage, cracking, or peeling of the coating layer was observed.

[Effect of the invention 1] Since the exhaust system equipment of the present invention contains A-quality fibers in the heat insulating layer and/or the fireproof layer, it not only has excellent heat resistance and fire resistance, but also has excellent thermal shock resistance, Vibration resistance and distortion resistance are also affected.

Therefore, it has a long service life without cracking or peeling even under actual exhaust gas conditions.

Claims (8)

[Claims] (1) An exhaust system device having a heat insulating layer on its inner surface, wherein the heat insulating layer is made of heat insulating powder and inorganic fiber. (2) The exhaust system equipment according to claim 1, wherein the heat insulating layer is made of a mixture of the heat insulating material powder and the inorganic fiber. (3) The exhaust system equipment according to claim 1, wherein the heat insulating layer is formed by laminating a layer made of the heat insulating material powder and a layer made of the inorganic fiber. . (4) The exhaust system equipment according to any one of claims 1 to 3, characterized in that the exhaust system equipment has a fire-resistant layer mainly made of fire-resistant material powder on the heat-insulating layer. . (5) The exhaust system device according to claim 4, wherein the fireproof layer contains the inorganic fiber or a ceramic fiber that has better fire resistance than the inorganic fiber. (6) The exhaust system equipment according to claim 5, wherein the inorganic fiber or the ceramic fiber is mixed with the refractory material powder. (7) The exhaust system equipment according to claim 5, characterized in that the layer of the inorganic fiber or the ceramic fiber is laminated with the layer of the refractory material powder to constitute the refractory layer. exhaust system equipment. (8) An exhaust system device having a heat insulating layer on its inner surface, wherein the heat insulating layer is made only of inorganic fibers.