Emission control system

Claim 3

The method recited in claim 1 wherein said conversion efficiency of the first catalyst is further determined based on a temperature of the first catalyst.

Claim 4

The method recited in claim 1 wherein said first reductant quantity is further based on a temperature of the first catalyst.

Claim 5

The method recited in claim 3 wherein said second reductant quantity is further based on a temperature of the second catalyst.

Claim 6

The method recited in claim 4 wherein said temperature of the first catalyst and said temperature of the second catalyst are based on a measured temperature between the first catalyst and the second catalyst.

Claim 7

The method recited in claim 5 wherein said temperature of the first catalyst is an increased value of said measured temperature and said temperature of the second catalyst is a decreased value of said measured temperature.

Claim 8

The method recited in claim 5 wherein an amount of increasing or decreasing of said increased and decreased values is based on a throttle position and an engine speed.

Claim 9

The method recited in claim 1 wherein said operating conditions are an engine speed and an engine fuel injection quantity.

Claim 10

The method recited in claim 1 wherein said first quantity is modified based on an air charge temperature entering the engine.

Claim 11

The method recited in claim 1 wherein said first quantity is modified based on an exhaust gas recirculation rate.

Claim 12

The method recited in claim 1 wherein said first quantity is modified based on a start of injection timing of fuel injected into the engine.

Claim 15

The method recited in claim 12 wherein said second reductant injection quantity is further based on a temperature of the second catalyst.

Claim 16

The method recited in claim 12 wherein said temperature of the first catalyst and said temperature of the second catalyst are based on a measured temperature between the first catalyst and the second catalyst.

Claim 17

The method recited in claim 13 wherein said temperature of the first catalyst is an increased value of said measured temperature and said temperature of the second catalyst is a decreased value of said measured temperature.

Claim 18

The method recited in claim 14 wherein an amount of increasing or decreasing of said increased and decreased values is based on a throttle position and an engine speed.

Claim 19

The method recited in claim 12 wherein said first injection quantity is modified based on an engine coolant temperature.

Claim 20

The method recited in claim 12 wherein said first injection quantity is modified based on an exhaust gas recirculation rate.

Claim 21

The method recited in claim 12 wherein said first injection quantity is modified based on a start of injection timing of fuel injected into the engine.

Claim 22

An article of manufacture comprising: a computer storage medium having a computer program encoded therein for controlling the amount of reductant adding to first and second catalysts serially disposed in an engine exhaust, said computer storage medium comprising: code for generating a first reductant quantity based on engine operating conditions representative of a nitrogen oxide quantity produced by the engine; code determining a conversion efficiency of the first catalyst based on operating conditions; code for generating a second reductant quantity based on said first reductant injection quantity and said conversion efficiency; code for adding reductant to the first catalyst according to said first reductant quantity; and code for adding reductant to the second catalyst according to said second reductant quantity.

Claim 23

An article of manufacture comprising: a computer storage medium having a computer program encoded therein for controlling the amount of reductant adding to first and second catalysts serially disposed in an engine exhaust, said computer storage medium comprising: code for generating a first reductant quantity based on engine operating conditions representative of a nitrogen oxide quantity produced by the engine; code determining a conversion efficiency of the first catalyst based on operating conditions; code for generating a second reductant quantity based on said first reductant injection quantity and said conversion efficiency; code for adding reductant to the first catalyst according to said first reductant quantity; and code for adding reductant to the second catalyst according to said second reductant quantity.

Claim 24

The article recited in claim 20 , further comprising: code for generating said first reductant quantity based on engine operating conditions representative of said nitrogen oxide quantity produced by the engine and a temperature of the first catalyst, wherein said first quantity is modified based on an air charge temperature entering the engine, an exhaust gas recirculation rate, and a start of injection timing of fuel injected into the engine; code for determining said conversion efficiency of the first catalyst based on an engine speed, said temperature of the first catalyst, and an engine fuel injection quantity; and code for generating said second reductant quantity based on said first reductant quantity, said conversion efficiency, and a temperature of the second catalyst; wherein said temperature of the first catalyst is an increased value of a measured temperature between the first catalyst and the second catalyst and said temperature of the second catalyst is a decreased value of said measured temperature between the first catalyst and the second catalyst.