Exhaust gas catalytic purifier construction

• US 5,569,455 A
• Filed: 01/03/1995
• Issued: 10/29/1996
• Est. Priority Date: 06/10/1992
• Status: Expired due to Fees

• Current Assignee: Mazda Motor Corporation, Shimadzu Corporation
• Original Assignee: Mazda Motor Corporation, Shimadzu Corporation
• Inventors: Inoue, Koji, Takahashi, Masamitsu, Tanaka, Tetsuhiro, Fukui, Isao, Ihara, deceased, Kazunori, Murakami, Hiroshi, Kuroda, Shinichi, Miyaura, Shinobu, Hiraishi, Masahiro
• Primary Examiner(s): Warden, Robert
• Assistant Examiner(s): TRAN, HIEN THI
• Application Number:
  US08/367,925
• Time in Patent Office: 665 Days
• Field of Search: 422/171, 422/173-174, 422/177, 422/179, 422/180, 422/199, 422/221-222, 60/299, 60/300, 502/439, 502/527
• US Class Current: 422/174
• CPC Class Codes: B01D 53/945 characterised by a specific catalyst
• CPC Class Codes: B01D 53/9454 characterised by a specific device
• CPC Class Codes: B01J 35/33 Electric or magnetic properties
• CPC Class Codes: B01J 35/56 Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
• CPC Class Codes: B01J 37/0238 via the gaseous phase-sublimation
• CPC Class Codes: B01J 37/0244 Coatings comprising several layers
• CPC Class Codes: F01N 2330/02 Metallic plates or honeycombs, e.g. superposed or rolled-up corrugated or otherwise deformed sheet metal
• CPC Class Codes: F01N 2330/06 Ceramic, e.g. monoliths
• CPC Class Codes: F01N 2330/10 Fibrous material, e.g. mineral or metallic wool
• CPC Class Codes: F01N 2330/12 Metallic wire mesh fabric or knitting
• CPC Class Codes: F01N 3/2026 directly electrifying the catalyst substrate, i.e. heating the electrically conductive catalyst substrate by joule effect
• CPC Class Codes: F01N 3/2803 characterised by structure, by material or by manufacturing of catalyst support
• CPC Class Codes: F01N 3/2807 Metal other than sintered metal F01N3/2832 and F01N3/2835 take precedence
• CPC Class Codes: F01N 3/281 Metallic honeycomb monoliths made of stacked or rolled sheets, foils or plates
• CPC Class Codes: F01N 3/2817 only with non-corrugated sheets, plates or foils
• CPC Class Codes: F01N 3/2825 Ceramics F01N3/2832, F01N3/2835 take precedence
• CPC Class Codes: F01N 3/2828 Ceramic multi-channel monoliths, e.g. honeycombs
• CPC Class Codes: F01N 3/2835 fibrous
• CPC Class Codes: F01N 3/2853 using mats or gaskets between catalyst body and housing
• CPC Class Codes: F01N 3/2864 the mats or gaskets comprising two or more insulation layers
• CPC Class Codes: Y02T 10/12 : Improving ICE efficiencies

Abstract

Method of forming a catalytic bonding layer by chemical vapor deposition (CVD) onto carrier structures including internal combustion engine exhaust system and catalytic converter components, in order to bond a catalyst layer thereto, thereby providing a structure wherein additionally the bonding layer can be energized to promote catalytic conversion-activating preheating of the catalyst. In an electromagnetic induction catalytic preheating system, a ceramic lattice or a metallic network can form the base structure of the catalytic converter, wherein at least the latter is encompassed by an electrical/thermal insulating layer; around either induction coiling is wrapped and secured by a thermally insulating material. Upon engine start, current is electromagnetically induced in the catalytic bonding layer or the metallic network through the induction coiling. Furthermore, the specific heat capacity of the bonding layer is low, and its specific resistance can be predetermined; thus in heating quickly and efficiently, in tandem the catalyst is heated. The catalytic preheating is also made efficient by the insulating properties of the insulating layers.

Claims

1. A combination comprising:

a source of exhaust gas containing noxious fumes;

an exhaust gas catalytic purifier operatively associated with said source of said exhaust gas comprising;

a housing containing;

a catalyst carrier;

a substantially uniform, electrically energizable bonding layer, in at least one form selected from the group consisting of a layer of gross structural crystals, a film of columnar shaped crystals, and an intermetallic compound,

wherein said bonding layer has been formed by chemical vapor deposition on said catalyst carrier,

wherein said bonding layer is supported by said catalyst carrier,

wherein said bonding layer has a heat capacity sufficient to generate heat upon being energized,

wherein said bonding layer has a substantially uniformly formed, sufficiently rough surface to firmly bond a catalyst layer thereto,

wherein said bonding layer comprises;

at least one carbide selected from the group consisting of tungsten carbide, molybdenum carbide, silicon carbide, and carbides of alloys of said metals, or

at least one silicide selected from the group consisting of tungsten silicide, molybdenum silicide, tantalum silicide, titanium silicide, and silicides of alloys of said metals; and

a catalyst layer disposed on and firmly bonded to said rough surface of said bonding layer disposed away from said catalyst carrier and supported by said catalyst carrier;

means to energize said bonding layer which electromagnetic induction means comprising;

coil means disposed on a peripheral portion of said catalyst carrier, and

high frequency generator means in operative contact with said coil means;

wherein said generator is sufficient to supply a current to said coil means of a frequency high enough to energize said bonding layer;

wherein said electromagnetic induction means is sufficient to generate heat which is sufficient to heat said catalyst to an operating temperature sufficient to cause the conversion of said noxious fumes and to thereby convert noxious fumes in said exhaust gas;

means to introduce said exhaust gas into operative association with said catalyst layer which has been heated by said energized bonding layer; and

means to remove catalytically converted exhaust gas, containing less of said noxious fumes, from said purifier.

2. The combination as claimed in claim 1 wherein said catalyst carrier comprises a filter lattice comprising carbon.

3. The combination as claimed in claim 1 wherein said catalyst carrier comprises a filter lattice comprising ceramic.

4. The combination as claimed in claim 2 wherein said filter lattice comprises a honeycomb filter lattice.

5. The combination as claimed in claim 3 wherein said filter lattice comprises a honeycomb filter lattice.

6. The combination as claimed in claim 1 wherein said catalyst carrier comprises a filter lattice comprising metallic fibers.

7. The combination as claimed in claim 1 wherein said catalyst carrier comprises a filter mesh comprising metallic fibers.

8. The combination as claimed in claim 1 wherein said catalyst carrier comprises a filter honeycomb metallic structure.

9. The combination as claimed in claim 1 wherein said bonding layer comprises a film of columnar structured ceramic crystals, which film has a rough surface bonded to said catalyst layer.

10. The combination as claimed in claim 1 wherein said bonding layer comprises a layer of gross structured ceramic crystals, which layer has a rough surface bonded to said catalyst layer.

11. The combination as claimed in claim 1 wherein said bonding layer comprises an intermetallic compound which has a rough surface bonded to said catalyst layer.

12. The combination comprising:

a source of exhaust gas containing noxious components; and

an exhaust gas catalytic purifier comprising;

a metallic exhaust gas conduit, comprising an inside wall and an outside wall, which conduit contains;

a substantially uniform, electrically energizable bonding layer in at least one form selected from the group consisting of a layer of gross structural crystals, a film of columnar shaped crystals, and an intermetallic compound,

which bonding layer has been formed by chemical vapor deposition on said inside wall of said conduit,

which bonding layer is supported by said inside wall of said conduit,

wherein said bonding layer has a heat capacity sufficient to generate heat upon being energized,

wherein said bonding layer has a substantially uniformly formed, sufficiently rough surface to firmly bond a catalyst layer thereto,

wherein said bonding layer comprises;

at least one carbide selected from the group consisting of tungsten carbide, molybdenum carbide, silicon carbide, and carbides of alloys of said metals, or

at least one silicide selected from the group consisting of tungsten silicide, molybdenum silicide, tantalum silicide, titanium silicide, and silicides of alloys of said metals;

a catalyst layer disposed on and firmly bonded to said rough surface of said bonding layer directed away from said conduit;

means to energize said bonding layer which comprises electromagnetic induction means comprising;

coil means disposed on a peripheral portion of said catalyst carrier, and

high frequency generator means in operative contact with said coil means;

wherein said generator is sufficient to supply a current to said coil means of a frequency high enough to energize said bonding layer to an extent sufficient to generate heat which is sufficient to heat said catalyst to an operating temperature sufficient to cause the conversion of said noxious fumes and to thereby convert noxious fumes in said exhaust gas;

means to introduce said exhaust gas containing noxious components into said metallic gas conduit;

means to contact said noxious fumes with said catalyst layer heated by said energized bonding layer under conditions sufficient to convert noxious fumes; and

means to remove exhaust gas, containing a smaller proportion of noxious fumes, from said purifier.

13. The combination as claimed in claim 12 further comprising an electrically and thermally insulating layer, formed by chemical vapor deposition, disposed between said conduit and said bonding layer.

14. The combination of;

a source of exhaust gas containing noxious fumes;

an exhaust gas passage having an inside surface, operatively associated with said source so as to pass said exhaust gas therethrough;

an exhaust gas catalytic purifier disposed within said exhaust gas passage comprising;

an electromagnetic induction heating coil means disposed inwardly of said exhaust gas passage disposed on said inside surface of said passage;

a heat conductive means disposed on an inwardly directed portion of said electromagnetic induction heating coil means in heatable relation to said induction coil heating means disposed in said exhaust gas passage; and

exhaust gas conversion catalyst inwardly disposed on and carried by said heat conductive means so positioned as to be heatable by said heat conductive means and in operative contact with noxious fumes in exhaust gas passing through said passage;

wherein said induction heating coil means is disposed in sufficiently close proximity to said conductive means to cause current to pass through said conductive means via electromagnetic induction in an amount sufficient to cause said conductive means to become heated and to thereby heat said catalyst;

a ceramic support lattice disposed on said inside surface of said exhaust gas passage in supporting relation to said induction heating coil means;

wherein said conductive means comprises a substantially uniform, electrically energizable rough bonding layer in at least one form selected from the group consisting of a layer of gross structural crystals, a film of columnar shaped crystals, and an intermetallic compound;

wherein said bonding layer has been formed by chemical vapor deposition;

wherein said bonding layer has been formed onto and is bonded to said ceramic support lattice;

wherein said bonding layer comprises;

at least one carbide selected from the group consisting of tungsten carbide, molybdenum carbide, silicon carbide, and carbides of alloys of said metals, or

at least one silicide selected from the group consisting of tungsten silicide, molybdenum silicide, tantalum silicide, titanium silicide, and silicides of alloys of said metals;

wherein said catalyst is disposed on and is bonded to said bonding layer; and

a generator sufficient to supply current to said induction heating coil of sufficient frequency and magnitude to cause said induction heating coil to produce an alternating magnetic flux of sufficient magnitude to cause current to flow in said conductive means in an amount sufficient to generate sufficient heat to heat said catalyst to a temperature at which said catalyst is operative to catalyze conversion of noxious fumes in said exhaust gas.

15. The combination as claimed in claim 14 further comprising heat resistant means securing said induction heating coil means to said conductive means.

16. The combination as claimed in claim 15 wherein said securing means comprises spray coated ceramic.

17. The combination as claimed in claim 14 further comprising temperature sensor means, in measuring association with said catalyst to measure the temperature of said catalyst, and means to control the amount of said current supplied to said induction heating coil means responsive to a temperature sensed by said temperature sensor means, whereby controlling the temperature of said catalyst.

18. The combination as claimed in claim 14 wherein said catalyst and conductive means are divided into a downstream main portion and an upstream sub-portion, said sub-portion disposed between said main portion and said source of exhaust gas;

and wherein said induction heating coil mean is operatively associated with said upstream sub-portion of said catalyst and conductive means.

19. The combination as claimed in claim 14 wherein said bonding layer is an electromagnetically conductive layer which is heatable through electromagnetic induction from said induction heating coil means.

20. The combination of;

a source of exhaust gas containing noxious fumes;

an exhaust gas passage having an inside surface, configured to pass said exhaust gas therethrough;

an exhaust gas catalytic purifier inside said exhaust gas passage comprising;

an electrically non-conductive support;

an electrically conductive means; and

an exhaust gas conversion catalyst;

an electromagnetic induction coil means disposed on an inside surface of said exhaust gas passageway in sufficiently close proximity to said electrically conductive means to cause current to pass through said electrically conductive means via electromagnetic induction in an amount sufficient to cause said electrically conductive means become heated and to thereby heat said catalyst to a conversion temperature,

said electrically non-conductive support is disposed on an inside surface of said coil,

said electrically conductive means is disposed on an inside surface of said electrically non-conductive support,

wherein said catalyst is disposed on and carried by an inside surface of said electrically conductive means and is in sufficiently close proximity to said electrically conductive means to be heated by said electrically conductive means;

wherein said conductive means comprises a substantially uniform, electrically energizable rough bonding layer in at least one form selected from the group consisting of a layer of gross structural crystals, a film of columnar shaped crystals, and an intermetallic compound;

wherein said bonding layer has been formed by chemical vapor deposition;

wherein said bonding layer has been formed onto and is bonded to said electrically non-conductive support;

wherein said bonding layer comprises;

at least one carbide selected from the group consisting of tungsten carbide, molybdenum carbide, silicon carbide, and carbides of alloys of said metals, or

at least one silicide selected from the group consisting of tungsten silicide, molybdenum silicide, tantalum silicide, titanium silicide, and silicides of alloys of said metals;

wherein said catalyst is disposed on and is bonded to said bonding layer; and

generator means sufficient to supply current to said induction coil of sufficient frequency and magnitude to cause said induction coil to produce an alternating magnetic flux of sufficient magnitude to cause current to flow in said electrically conductive means in an amount sufficient to generate sufficient heat to heat said catalyst to a temperature at which said catalyst is operative to catalyze conversion of noxious fumes in said exhaust gas.

21. The combination as claimed in claim 20 wherein said electrically non-conductive support comprises an electrically and thermally insulating layer.

22. The combination as claimed in claim 20 wherein said electrically non-conductive support is a ceramic support lattice, said electrically conductive means is in partial contact with said ceramic support lattice. and wherein the resistance of said electrically conductive layer is determined by the amount of said contact.