Patent ID: 8490388

Claim:
A method of controlling a outlet temperature of an oxidation catalyst for an engine having an exhaust means including an oxidation catalyst comprising the steps of: (i) sensing temperature at an inlet of the oxidation catalyst; (ii) measuring an exhaust mass flow rate in the exhaust means; (iii) calculating a value representing a post quantity of fuel to be introduced to the engine to generate an exothermic reaction in the oxidation catalyst based on a pre-determined desired outlet temperature of the oxidation catalyst, characterised in that the calculation representing the oxidation catalyst uses a steady state model utilizing the exhaust mass flow rate, the inlet temperature of the oxidation catalyst and compensating the steady state model for transients comprising calculating a compensating function dependent on stored energy in the oxidation catalyst and exhaust mass flow rate; and (iv) instructing a quantity of fuel equivalent to the post fuel value to be introduced to the engine; wherein the steady state model corresponds to the following equation: q . post = 1 1 - burn_frac post ⁡ [ m . · c p · ( T o - T i ) ( 1 - η exh ⁢ _ ⁢ man ) · η DOC · H - ∑ i ⁢ q . fi · ( 1 - burn_frac i ) ] , where {dot over (q)} post is the post fuel value, T o is the pre-determined desired outlet temperature, T i is the inlet temperature of the oxidation catalyst, {dot over (m)} is the exhaust mass flow rate, ∑ i ⁢ q . fi is the initial fuel value and [ ∑ i ⁢ q . fi · ( 1 - burn_frac i ) ] is the total amount of unburned fuel leaving the engine except the post fuel value, (1−η exh — man ) is the first efficiency fraction, (1−burn_frac i ) is the second efficiency fraction, c p is the specific heat of the exhaust gas, H is the fuel heating value and η DOC is the exothermal efficiency for unburned fuel of the oxidation catalyst.