Patent Application
20170002717
The present invention relates to a heat-shielding cover of an exhaust system part. Heat-shielding covers are often installed on the exhaust system part, covering the same, using an installation member. Heat-shielding covers can be used to prevent thermal damage to the exhaust system part from high temperature of an internal combustion engine. The present invention also relates to a method of production thereof.
Heat-shielding cover for an exhaust system part is already known, as is disclosed in Japanese Unexamined Patent Publication No. 2010-156372. A heat-shielding cover of an exhaust system part disclosed in Japanese Unexamined Patent Publication No. 2010-156372 includes an aluminum sheet having a comparatively large thermal expansion coefficient. Accordingly, in this sort of heat-shielding cover, a metal buffer material is interposed between the heat-shielding cover and the installation member so that warping due to thermal expansion and contraction of the heat-shielding cover does not occur in the installation member of the heat-shielding cover and impair the durability of the same; therefore, the structure surrounding the installation member becomes complex, and moreover, countermeasures for galvanic corrosion occurring due to the use of heterogeneous metals also are required surrounding the installation member.
The present invention was created, in part, in consideration of such circumstances. An object of the present invention is to provide a heat-shielding cover of an exhaust system part, that has one or any combination of the following advantages: a simple structure, is not subject to warping in the place of installation due to thermal expansion and contraction of the heat-shielding cover, and is not susceptible to galvanic corrosion, even as a result of direct installation using an installation member. Another object of the present invention is to provide a method of production thereof.
A first aspect of the present invention is a heat shield or heat-shielding cover operatively adapted (i.e., dimensioned, designed, and/or configured) for being installed adjacent to an exhaust system part so as to cover the same; the heat-shielding cover including a fabric provided with a prescribed shape and comprising inorganic fibers, and a mixture that impregnates the fabric, with the mixture including an inorganic binder, inorganic filler particles and water. The mixture is dried so as to be rigid enough to maintain the shape of the fabric. It is desirable for the fabric to be a woven or knitted fabric. One example of an exhaust system part suitable for use with the present invention is a catalytic converter.
A second aspect of the present invention is such that, in addition to the first aspect, the fabric is provided with at least a portion overlaid in multiple layers.
A third aspect of the present invention is an exhaust system that includes an exhaust system part and a heat-shielding cover, according to the first aspect, installed adjacent to the exhaust system part so as to cover the same.
A fourth aspect of the present invention is such that, during production of the heat-shielding cover according to the first aspect, the following steps are carried out: a step of molding a fabric impregnated with the mixture into the prescribed shape using at least one die, and a step of heating the die to to dry the mixture so as to be rigid enough to maintain the shape of the fabric.
A fifth aspect of the present invention is such that, in addition to the fourth aspect, releasing means not easily adhered to by the mixture is interposed between each die and the impregnated fabric.
According to the first aspect of the present invention, because the heat-shielding cover includes a fabric provided with a prescribed shape, and the mixture that impregnates the fabric is dried to maintain the shape of the fabric, the heat-shielding cover is excellent in heat-insulating property, and thermal damage to various kinds of devices or objects adjacent to the heat-shielding cover can be effectively prevented or at least significantly reduced. Moreover, because the heat-shielding cover has a very small thermal expansion coefficient and has a suitable degree of flexibility, the heat-shielding cover can follow thermal expansion and contraction of the exhaust system part (e.g., a catalytic converter, exhaust manifold, exhaust pipe, muffler, diesel particulate filter or trap, etc.), and there is no occurrence of thermal warping in the place of installation on the exhaust system part. Accordingly, direct installation of the heat-shielding cover using an installation member becomes possible, the installation structure can become simple, and a contribution can be made to cost reduction. Furthermore, because the heat-shielding cover can be made without metal components, the susceptibility of galvanic corrosion in the place of installation can be eliminated or at least significantly reduced.
According to the second aspect of the present invention, because the fabric is provided with at least a portion overlaid in multiple layers, the heat-insulating property and/or strength of the heat-shielding cover can be increased, at least at the portion overlaid in multiple layers.
According to the third aspect of the present invention, because an exhaust system is provided that includes an exhaust system part and a heat-shielding cover installed adjacent to the exhaust system part so as to cover the same, thermal damage to the exhaust system part located adjacent to the heat-shielding cover, or thermal damage to other devices or objects by heat from the exhaust system part located adjacent to the heat-shielding cover, can be effectively prevented or at least significantly reduced.
According to the fourth aspect of the present invention, in production of the heat-shielding cover of the first aspect, because the method includes a step of molding a fabric impregnated with a mixture into a prescribed shape using one or more dies, and a step of heating at least one die to dry the mixture so as to be rigid enough so the fabric maintains the prescribed shape, the fabric impregnated with the mixture can be provided with a shape using the one or more dies, the clay can be dried, and the heat-shielding cover can be produced efficiently.
According to the fifth aspect of the present invention, because releasing means not easily adhered to by the mixture is interposed between the dies and the impregnated fabric, the releasing means can be used to prevent the mixture from adhering to the dies. The releasing means corresponding to a releasing sheet 19, in one embodiment of the present invention, is to be described. The releasing means may also be a coating of a suitable release material applied to the surface of the dies to be in contact with the impregnated fabric.
An exemplary embodiment of the present invention is described below based on the attached drawings.
First, in
As illustrated in
The fabric can comprise inorganic fibers (e.g., continuous glass fibers, silica fibers, basalt fibers, polycrystalline fibers, heat treated refractory ceramic fibers or any combination thereof,) suitable for being formed into a fabric such as, for example, one or any combination of woven, and/or knitted into a fabric. A fabric preferably refers to a woven fabric, knitted fabric or a combination of these types of fabric. Only fabrics with sufficient structural integrity are useful in the present invention. For example, it is desirable for a fabric according to the present invention to exhibit sufficient strength (e.g., tensile strength) to survive being impregnated with the mixture, formed, dried and used as a heat shield. A fabric according to the present invention can be made from the same or different types of fibers. As discussed herein, the fabric of the heat-shielding cover is saturated, soaked, coated, sprayed or otherwise impregnated throughout all, most or at least a substantial portion of its thickness with the aqueous mixture so as to be wet and pliable. The fabric can be impregnated with the aqueous mixture before or after being formed into the shape of the heat-shielding cover. After impregnation, the heat-shielding cover is pliable. It is dried so as to form a rigid heat-shielding cover. As used herein, the term “dried” refers to the pliable heat-shielding cover being heated to a temperature that is hot enough and for a time that is long enough to cause the pliable heat-shielding cover (i.e., the aqueous mixture) to harden and become a rigid heat-shielding cover (i.e., a rigid mixture).
The aqueous mixture used to impregnate the fabric of exemplary heat-shielding cover is typically a slurry comprising water, an inorganic binder and inorganic filler particles, like that disclosed in International PCT Application Publication Number WO 2013/044012 A1, which is incorporated herein by reference in its entirety. Although the weight percent of each component within the slurry may vary, typically a given slurry comprises from about 20.0 to about 54.0 percent by weight (pbw) of water, from about 1.0 to about 36.0 pbw of one or more inorganic binders, and from about 10.0 to about 70.0 pbw of inorganic filler particles, based on a total weight of the slurry. More typically, a given slurry comprises from about 22.0 to about 45.0 pbw of water, from about 5.0 to about 30.0 pbw of one or more inorganic binders, and from about 20.0 to about 55.0 pbw of inorganic filler particles, based on a total weight of the slurry.
Although the particle size of the inorganic binder material is not limited, typically, the inorganic binder comprises inorganic binder particles having a maximum particle size of about 200 nm, preferably a maximum particle size of about 100 nm. More typically, the inorganic binder comprises inorganic binder particles having a particle size ranging from about 1.0 to about 100 nm. Even more typically, the inorganic binder comprises inorganic binder particles having a particle size ranging from about 4.0 to about 60 nm.
Further, although the particle size of the inorganic filler particles is not limited, typically, the inorganic filler particles have a maximum particle size of about 100 microns (μm). More typically, the inorganic filler particles have a particle size ranging from about 0.1 μm to about 100 μm. Even more typically, the inorganic filler particles have a particle size ranging from about 0.2 μm to about 50 μm.
The woven fabric 10 can be overlaid in multiple layers that overlap partially or completely. In the illustrated example, two layers of the impregnated fabric 10 partially overlap. The use of such multiple layers of the fabric 10 may be particularly desirable in portions of the heat-shielding cover 3 such as, for example, a portion requiring higher heat-shielding properties (e.g., a portion of the heat shield 3 covering a center portion of the catalytic converter C that comes to a particularly high temperature). Other areas for multiple layers of the fabric 10 can include portions where additional strength and/or toughness is required such as, for example, a passive binding (e.g., see the washer shaped piece of fabric 10 shown in
The woven fabric 10 can be provided with a plurality of slit-shaped or round heat-discharge holes 12 as needed. Moreover, a large number of mesh holes formed by the woven fabric 10 may be left unfilled with the mixture 11 so as to remain as ventilation holes.
The operation of this embodiment is next described.
During operation of the internal combustion engine, the catalytic converter C of the exhaust system of the internal combustion engine cleans the exhaust gas and is brought to a high temperature from the reaction heat of the cleaning. However, because the side surface of the catalytic converter C is covered by the heat-shielding cover 3, the heat-shielding cover 3 shields against the radiant heat of the catalytic converter C and prevents thermal damage to various kinds of devices or objects (e.g., organic matter on the ground underneath the catalytic converter C) adjacent to the catalytic converter C.
The heat-shielding cover 3 is also excellent in acoustic shielding, and can effectively shield against exhaust noise generated by the catalytic converter C.
The hot gas produced around the catalytic converter C is dissipated to the outside through the heat-discharge holes 12 and 12 . . . of the heat-shielding cover 3 or the large number of mesh holes of the woven fabric 10 configuring the heat-shielding cover 3. Therefore, overheating of the catalytic converter C can be prevented.
Moreover, as previously described, the heat-shielding cover 3 is configured with the woven fabric 10 containing a heat-resistant fiber 10, and with clay 11 that is impregnated within heat-resistant fiber 10 and dried. Therefore, the heat-shielding cover is excellent in heat-insulating property, and thermal damage to various kinds of devices adjacent thereto can be effectively prevented.
Because the heat-shielding cover 3 has a very small thermal expansion coefficient and has a suitable degree of flexibility, the heat-shielding cover can comply with thermal expansion and contraction of the catalytic converter C and there is no occurrence of thermal warping in the part fastened using the bolt 8. Accordingly, direct binding of the heat-shielding cover 3 using the bolt 8 becomes possible and a contribution is made to cost reduction.
Moreover, because the heat-shielding cover 3 has an insulating property, there is also no susceptibility to the occurrence of galvanic corrosion in the part bound using the bolt 8.
The following Examples of material combinations have been selected merely to further illustrate potential features, advantages, and other details of the invention. It is to be expressly understood, however, that while the Examples serve this purpose, the particular ingredients and amounts used as well as other conditions and details are not to be construed in a manner that would unduly limit the scope of this invention.
The following materials as shown in Table 1 can be used in accordance with the present invention:
Slurries can be prepared using ingredients shown above. In each slurry, inorganic materials can be added to liquid component(s) using a high shear mixer and blended until smooth to form a given slurry as shown in Table 2 below.
Each exemplary fabric can be impregnated with a given slurry to produce a given pliable heat-shielding cover, and subsequently formed and dried into a rigid heat-shielding cover via a drying/heat treatment molding procedure like that described below.
An exemplary method of production of the heat-shielding cover 3 is next described while referring to
A pair of upper and lower dies 15 and 16 for press-molding the heat-shielding cover 3 is prepared. Heaters 17 and 17 are embedded in the dies 15 and 16, and a plurality of steam escape slots 18 and 18 . . . is provided on facing surfaces of the dies 15 and 16.
When molding the heat-shielding cover 3, first, a releasing sheet 19 (e.g., made using aluminum foil) is laid on the lower die 16. A plurality of steam escape holes is provided in the releasing sheet 19 for the water in the mixture 11 to escape through when heated. A woven fabric 10 impregnated with aqueous mixture 11 is set on the releasing sheet 19. Then, as previously described, woven fabric 10 impregnated with mixture 11 is placed in multiple layers in places requiring high heat-shielding property or places requiring strength on the heat-shielding cover 3.
Moreover, a releasing sheet 19 of the same kind as mentioned above is laid on the woven fabric 10, and then, as illustrated in
According to such production method, a shape can be provided to a woven fabric 10 impregnated with mixture 10, and a heat-shielding cover 3 can be produced efficiently, using a pair of upper and lower dies 15 and 16.
The present invention is not limited to the abovementioned embodiment, and all kinds of design modifications are possible within a scope that does not deviate from the main point thereof. For example, a metal mesh, porous steel sheet, or other reinforcing material may be sandwiched between woven fabrics 10 overlaid in a plurality of sheets, or the reinforcing material may be provided on the top surface. Additionally, the material of the reinforcing material is not limited to metal, and may also be a heat-resistant resin or ceramic. Moreover, the heat-shielding cover 3 can be installed on the catalytic converter C using a band, or the like, instead of one or more bolts 8. Additionally, a releasing powder can be used on the dies 15 and 16 instead of the releasing sheet 19. The releasing sheets 19 and 19 may also be replaced with a coating of conventional release material that adheres to the dies 15 and 16 but not the heat-shielding cover 3. Moreover, the shape of the heat-shielding cover can be freely selected in accordance with the type or arrangement of the exhaust system part or with the arrangement of adjacent members. Furthermore, the present invention may be useful as a heat shield for applications other than for an exhaust system part. On such other application may be, for example, as a heat shield for other heat generating structures or for protecting heat sensitive areas of a structure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-262042 | Dec 2013 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2014/070700 | 12/17/2014 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61917961 | Dec 2013 | US |
