Multi-stage honeycomb heater
First Claim
1. A multi-stage honeycomb heater for heating fluid flowing therethrough, comprising:
- at least two honeycomb heaters electrically connected with each other to enable simultaneous energization of said at least two honeycomb heaters, which are disposed along a stream of fluid and include a furthest upstream honeycomb heater and an adjacent honeycomb heater which is adjacent to and downstream of the furthest upstream honeycomb heater;
each of said at least two honeycomb heaters having a honeycomb structure comprised of an electrically conductive material, the honeycomb structure having a periphery and two ends, including a plurality of passages which are defined by partition walls and extend in an axial direction between the ends;
the honeycomb structure of the furthest upstream honeycomb heater having at least one member selected from the group consisting of means for adjusting an electrical resistance of the honeycomb structure and means for adjusting a heat capacity of the honeycomb structure so that the ratio of applied power to heat capacity of the furthest upstream honeycomb heater is larger than the ratio of applied power to heat capacity of the adjacent honeycomb heater when said furthest upstream and adjacent honeycomb heaters are simultaneously energized.
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Accused Products
Abstract
A multi-stage honeycomb heater includes: at least two honeycomb heaters electrically connected with each other and disposed along a stream of fluid; the two honeycomb heaters including furthest upstream honeycomb heater and a an adjacent honeycomb heater which is adjacent to and downstream of the furthest upstream honeycomb heater; each of the two honeycomb heaters having an electrically conductive honeycomb structure the honeycomb structure of the upstream honeycomb heater having slits for adjusting its electrical resistance and/or element for adjusting heat capacity of the honeycomb structure so that the ratio of applied power to heat capacity of the furthest upstream honeycomb heater is larger than the ratio of applied power to heat capacity of the adjacent honeycomb heater. Thus the upstream heater and the downstream heater can give similar temperature increases without a temperature distribution along a flow direction during the engine warm-up. A catalyst composition is coated on the partition walls of the honeycomb structure, and the light-off temperature of the catalyst composition of the upstream honeycomb heater is lower than that of the adjacent honeycomb heater.
56 Citations
20 Claims
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1. A multi-stage honeycomb heater for heating fluid flowing therethrough, comprising:
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at least two honeycomb heaters electrically connected with each other to enable simultaneous energization of said at least two honeycomb heaters, which are disposed along a stream of fluid and include a furthest upstream honeycomb heater and an adjacent honeycomb heater which is adjacent to and downstream of the furthest upstream honeycomb heater; each of said at least two honeycomb heaters having a honeycomb structure comprised of an electrically conductive material, the honeycomb structure having a periphery and two ends, including a plurality of passages which are defined by partition walls and extend in an axial direction between the ends; the honeycomb structure of the furthest upstream honeycomb heater having at least one member selected from the group consisting of means for adjusting an electrical resistance of the honeycomb structure and means for adjusting a heat capacity of the honeycomb structure so that the ratio of applied power to heat capacity of the furthest upstream honeycomb heater is larger than the ratio of applied power to heat capacity of the adjacent honeycomb heater when said furthest upstream and adjacent honeycomb heaters are simultaneously energized. - View Dependent Claims (2, 3, 4, 5, 6, 7, 11, 12, 13, 14)
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8. A multi-stage honeycomb heater for heating fluid flowing therethrough, comprising:
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at least two honeycomb heaters electrically connected with each other and disposed along a stream of fluid, each of said at least two honeycomb heaters having (i) a honeycomb structure comprised of an electrically conductive material, the honeycomb structure having a periphery and two ends, including a plurality of passages which are defined by partition walls and extend in an axial direction between the ends, and (ii) a catalyst composition, coated on the partition walls of the honeycomb structure, said catalyst composition comprising a heat resistant inorganic oxide and a catalytically active noble metal loaded on the inorganic oxide, said at least two honeycomb heaters including a furthest upstream honeycomb heater and an adjacent honeycomb heater which is adjacent to and downstream of the furthest upstream honeycomb heater, wherein the light-off temperature of the catalyst composition of the furthest upstream honeycomb heater is lower than the light-off temperature of the catalyst composition of the adjacent honeycomb heater. - View Dependent Claims (9, 10, 15, 16, 17, 18)
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19. A method for operating a multi-stage honeycomb heater, comprising the steps of:
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providing a multi-stage honeycomb heater having at least two honeycomb heaters electrically connected to each other, said at least two honeycomb heaters having a furthest upstream honeycomb heater and an adjacent honeycomb heater which is adjacent to and downstream of the furthest upstream honeycomb heater, each of said at least two honeycomb heaters having (i) a honeycomb structure composed of an electrically conductive material, the honeycomb structure having a periphery and two ends, including a plurality of passages which are defined by partition walls and extend in an axial direction between the ends, and (ii) a catalyst composition coated on the partition walls of the honeycomb structure, said catalyst composition comprising a heat resistant inorganic oxide, and a catalytically active noble metal loaded on the inorganic oxide, wherein the honeycomb structure of the furthest upstream honeycomb heater has at least one member selected from the group consisting of means for adjusting an electrical resistance of the honeycomb structure and means for adjusting a heat capacity of the honeycomb structure so that the ratio of applied power to heat capacity of the furthest upstream honeycomb heater is larger than the ratio of applied power to heat capacity of the adjacent honeycomb heater when the furthest upstream and adjacent honeycomb heaters are simultaneously energized; flowing exhaust gas through the multi-stage honeycomb heater from an automobile engine; energizing the multi-stage honeycomb heater prior to engine start-up to heat at least the furthest upstream honeycomb heater to the light-off temperature of the catalyst composition thereof.
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20. A method for operating a multi-stage honeycomb heater, comprising the steps of:
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providing a multi-stage honeycomb heater having at least two honeycomb heaters electrically connected to each other, said at least two honeycomb heaters having a furthest upstream honeycomb heater and an adjacent honeycomb heater which is adjacent to and downstream of the furthest upstream honeycomb heater, each of said at least two honeycomb heaters having (i) a honeycomb structure composed of an electrically conductive material, the honeycomb structure having a periphery and two ends, including a plurality of passages which are defined by partition walls and extend in an axial direction between the ends, and (ii) a catalyst composition coated on the partition walls of the honeycomb structure, said catalyst composition comprising a heat resistant inorganic oxide, wherein the honeycomb structure of the furthest upstream honeycomb heater has at least one member selected from the group consisting of means for adjusting an electrical resistance of the honeycomb structure and means for adjusting a heat capacity of the honeycomb structure so that the ratio of applied power to heat capacity of the furthest upstream honeycomb heater is larger than the ratio of applied power to heat capacity of the adjacent honeycomb heater when the furthest upstream and adjacent honeycomb heaters are simultaneously energized; flowing exhaust gas through the multi-stage honeycomb heater from an automobile engine; and energizing said multi-stage honeycomb heater substantially simultaneously with engine start-up to heat at least the furthest upstream honeycomb heater to the light-off temperature of the catalyst composition thereof, within 30 seconds from engine start-up.
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Specification