Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – Waste gas purifier
Reexamination Certificate
1993-08-20
2001-06-12
Tran, Hien (Department: 1764)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
Waste gas purifier
C422S180000, C422S221000, C422S222000, C428S920000
Reexamination Certificate
active
06245301
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to catalytic converters and diesel particulate filters or traps.
DESCRIPTION OF THE RELATED ART
High temperature intumescent mounting mats are commonly used to hold monoliths (e.g., catalytic converter elements or diesel particulate filters) in place while resisting erosion of gases at moderate pressure pulsations and temperatures (typically less than about 750° C.). For example, intumescent mounting mats do an adequate job of holding a ceramic monolith or diesel particulate filter in place with exhaust temperatures of less than about 750° C. and with moderate pressure pulsations of exhaust gases such as are commonly encountered with six or eight cylinder engines. However, in high performance automobiles and heavy duty trucks, the intumescent mounting mat is typically subjected to higher temperatures and more severe pressure pulsations. Under these more severe conditions, over a period of time, the intumescent material making up the mat if left unprotected can be eroded.
Solutions to the problem include the use of a stainless steel wire screen (see e.g., U.S. Pat. No. 5,008,086 (Merry)) and braided or rope-like ceramic (i.e., glass, crystalline ceramic, or glass-ceramic) fiber braiding or metal wire material (see, e.g., U.S. Pat. No. 4,156,33 (Close et al.)) to protect the edge of the intumescent mat from erosion by exhaust gases.
SUMMARY OF THE INVENTION
The present invention provides a catalytic converter (or diesel particulate filter) comprising a metallic casing, a catalytic converter element (or diesel particulate filter element) disposed within the metallic casing, and a mounting mat disposed between the catalytic converter element (or diesel particulate filter element) and the metallic casing for positioning the catalytic converter element (or diesel particulate filter element) within the metallic casing and for absorbing mechanical vibration (i.e., at least partially damping mechanical vibrations), the mounting mat comprising:
(a) an intumescent mounting mat having first and second opposed major surfaces, a leading edge, and a trailing edge; and
(b) an edge protectant material covering at least a portion of at least one of the leading or the trailing edges (i.e., the leading edge or the trailing edge) to reduce erosion of at least one of the leading or the trailing edges when exposed to hot, impinging gases (i.e., above about 300° C., preferably above about 350° C., more preferably above about 500° C., and even more preferably above about 750° C.), the edge protectant material comprising binder material in the range from about 5 to about 85 percent by weight and dispersed (uniformly or nonuniformly) therein glass particles in the range from about 95 to about 15 percent by weight, based on the total weight of the binder material and the glass particles, wherein the glass particles are made of a glass having a softening point of at least about 350° C., and wherein the combined weight of the binder material and the glass particles is at least 20 percent by weight (preferably, at least about 35 percent by weight, more preferably, at least about 50 percent by weight, and, most preferably, at least about 75 percent by weight) of the total weight of the edge protectant material.
In another aspect, a catalytic converter (or diesel particulate filter) comprising a metallic casing, a catalytic converter element (or diesel particulate filter element) disposed within the metallic casing, and a mounting mat disposed between the catalytic converter element (or diesel particulate filter element) and the metallic casing for positioning the catalytic converter element (or diesel particulate filter element) within the metallic casing and for absorbing mechanical vibration, the mounting mat comprising the heated product of:
(a) an intumescent mounting mat having two opposed major surfaces, a leading edge, and a trailing edge; and
(b) the edge protectant material covering at least a portion of at least one of the leading or the trailing edges to reduce erosion of at least one of the leading or the trailing edges when exposed to hot, impinging gases.
In another aspect, the present invention provides a catalytic converter (or diesel particulate filter) comprising:
(a) a metallic casing;
(b) a catalytic converter element (or diesel particulate filter element) disposed within the metallic casing;
(c) an intumescent mounting mat having two opposed major surfaces, a leading edge, and a trailing edge disposed between the catalytic converter element (or diesel particulate filter element) and the metallic casing for positioning the catalytic converter element (or diesel particulate filter element) within the metallic casing and for absorbing mechanical vibration; and
(d) the edge protectant material disposed between the metallic casing and the catalytic converter element (or diesel particulate filter element) and positioned with respect to at least one of the leading or the trailing edges of the mounting mat such that erosion of at least a portion of at least one of the leading or the trailing edges is reduced when exposed to hot, impinging gases.
In yet another aspect, the present invention provides a catalytic converter (or diesel particulate filter) comprising:
(a) a metallic casing;
(b) a catalytic converter element (or diesel particulate filter element) disposed within the metallic casing; and
(c) the heated product of:
(i) an intumescent mounting mat having two opposed major surfaces, a leading edge, and a trailing edge disposed between the catalytic converter element (or diesel particulate filter element) and the metallic casing for positioning the catalytic converter element (or diesel particulate filter element) within the metallic casing and for absorbing mechanical vibration; and
(ii) the edge protectant material disposed between the metallic casing and the catalytic converter element (or diesel particulate filter element), and positioned with respect to at least one of the leading or the trailing edges of the mounting mat such that erosion of at least a portion of at least one of the leading or the trailing edges is reduced when exposed to hot, impinging gases.
In embodiments according to the present invention, the glass particles are capable of forming and are arranged to form a cohesive mass during the use of the catalytic converter or diesel particulate filter, the cohesive mass being capable of forming at a temperature not greater than 950° C. (see, e.g., Example 1).
In this application:
“leading edge” is the surface on one end of the mounting mat or the intumescent sheet material that extends between its first and second opposed major surfaces, and which is at the gas inlet side of the catalytic converter element (or the diesel particulate filter element);
“trailing edge” is the surface which is opposite to the leading edge, which extends between the first and second (opposed) major surfaces of the mounting mat or the intumescent sheet material, and which is at the gas outlet side of the catalytic converter element (or the diesel particulate filter element);
“binder material” refers to polymeric and other organic components of the edge protectant material that impart flexibility and hold the glass particles together;
“resilient” refers to the ability of a sheet or mat to conform to a curved surface (i.e., to wrap around a curved surface) without undesirable buckling or cracking of the sheet or mat;
“to reduce erosion of the lateral edge when exposed to hot, impinging gases” refers to the reduction in erosion of at least one of the leading or the trailing edges of the mounting mat by hot, impinging gases due to the presence of the edge protectant material;
“conformable” refers to the ability of the edge protectant material to accommodate dimensional changes during heating to, cooling from, and at use temperatures;
“glass frit” refers to glass (e.g., silicate glass) that has been melted and quenched (e.g., in water or air) to form small, friable glass particles;
“glass” as used herein refers to an amorphous (i.e., a material having a di
Howorth Gary F.
Schweitzer Michael T.
Stroom Paul D.
3M Innovative Properties Company
Allen Gregory D.
Tran Hien
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