US 8,418,442 B2 · Method and system for controlling active regeneration of a diesel particulate filter

Abstract

Method of controlling the active regeneration of a particulate filter through dynamic control of the temperature at the outlet of an oxidation catalyst. A control law is defined for a hydrocarbon flow rate at the oxidation catalyst inlet, by means of the ratio between a temperature demand and a gain. The gain can be corrected so as to take account of the transient phenomena that occur in the oxidation catalyst during a gas flow rate variation. The temperature demand can comprise a precompensation term to compensate for the effects of a temperature variation at the oxidation catalyst inlet. The temperature demand can comprise a feedback term calculated by a controller whose parameters are automatically calculated by means of a physical model of the catalyst, during operating conditions variations. Any combination of these terms allows to define a suitable control law. Finally, the hydrocarbon flow rate is modified by applying the control law so that the temperature of the gas leaving said catalyst respects a set point temperature. Application: engine control.

Claims15

Dependent claims

A method of treating the exhaust gas of an internal-combustion engine equipped with a particulate filter and an oxidation catalyst arranged upstream from said filter, wherein active regeneration of said filter is controlled by means of a dynamic control of a temperature T2 of said gas leaving said oxidation catalyst, the method comprising the following steps:

i-determining a set point temperature Tc of said gas leaving said catalyst so as to provide active regeneration of said filter,
ii-determining a temperature demand necessary for control of said temperature T2,
iii-determining a stationary gain G defined as the ratio between the stationary value of a variation of T2 and a stationary value of a hydrocarbon mass flow rate variation that has induced said variation of T2,
iv-correcting said gain G so as to take into account a gas flow rate variation at the inlet of said catalyst, the gain being transiently increased in relation to G for a gas flow rate increase and transiently decreased in relation to G for a gas flow rate decrease,
v-defining a control law for a hydrocarbon flow rate at the inlet of said oxidation catalyst, through the ratio of said temperature demand and said corrected gain,
vi-modifying the hydrocarbon flow rate by applying the control law so that the temperature of said gas leaving said catalyst meets said set point temperature.

3 more elements

i-determining a temperature demand TFF necessary to compensate for an effect of a variation of temperature T1 of said gas at the inlet of said catalyst, TFF being a function of a difference between T1(t−δ(t)) and a reference value Tbar, where T1(t−δ(t)) is an expression of a measurement of T1(t) delayed by a delay of value δ(t);
ii-determining a stationary gain G defined as the ratio between the stationary value of a variation of T2 and a stationary value of a hydrocarbon mass flow rate variation that has induced said variation of T2, all the other parameters remaining constant;
iii-defining a control law uFF of a hydrocarbon flow rate at the inlet of said oxidation catalyst, through the ratio between said temperature demand TFF and said gain,
iv-modifying the hydrocarbon flow rate by applying the control law so that the temperature of said gas leaving said catalyst meets said temperature demand TFF.

1 more element

i-determining a set point temperature Tc of said gas leaving said catalyst so as to provide active regeneration of said filter,
ii-determining a temperature demand TFB necessary for temperature T2 of said gas leaving said catalyst to meet said set point temperature Tc, said demand TFB being calculated from a controller whose parameters are determined by means of a physical model of the oxidation catalyst, based on an energy balance of a gas phase and an energy balance of a solid phase, as a function of the engine operating conditions,
iii-determining a stationary gain G defined as the ratio between the stationary value of a variation of T2 and a stationary value of a hydrocarbon mass flow rate variation that has induced said variation of T2,
iv-defining a control law uFB for a hydrocarbon flow rate at the inlet of said oxidation catalyst, through the ratio of said temperature demand TFF and said gain,
v-modifying the hydrocarbon flow rate by applying the control law so that the temperature of said gas leaving said catalyst meets said set point temperature.

2 more elements

Dependencies are inferred from the claim text.

Method and system for controlling active regeneration of a diesel particulate filter

Life of this patent

Method and system for controlling active regeneration of a diesel particulate filter

Life of this patent

Abstract

Claims15