Abstract: A method of optimizing vehicle emissions during lean engine operation is disclosed wherein an emission control device receiving engine exhaust gases is filled with one or more constituent gases of the exhaust gas to a predetermined fraction of the device storage capacity, and is then completely emptied during a subsequent purge. As the device storage capacity is substantially reduced, as indicated by an actual fill time becoming equal to or less than a predetermined minimum fill time, a device regeneration cycle is performed to attempt to restore device capacity. A programmed computer controls the fill and purge times based on the amplitude of the voltage of a switching-type oxygen sensor and the time response of the sensor. The frequency of the purge, which ideally is directly related to the device capacity depletion rate, is controlled so that the device is not filled beyond its storage capacity limit.

Abstract: A method and system are provided for adaptive control of a purge time and a fill time for an emission control device used to reduce emission of a selected constituent gas, such NOx, of an engine's generated exhaust gas, with optimization and adapting of stored values to reflect changes in device operating conditions. The invention determines a present value representative of the quantity of oxygen stored in the device, as well as a present value for the maximum device NOx-storage capacity to provide real-time adjustment of purge and fill time to achieve optimum overall operation of the device. The invention also periodically determines actual fill times which corresponding to optimal fill times to generate adaptive values for use during normal open-loop control.

Abstract: A system and method for optimizing the regeneration cycle of an emission control device, such as a lean NOx trap, is disclosed wherein the device is filled to a predetermined fraction of its existing capacity and is then completely emptied during a device purge. As device capacity is substantially reduced, as indicated by the actual fill time becoming equal to or less than a predetermined minimum fill time, a device desulfation event is performed to attempt to restore device capacity. A programmed computer controls the fill and purge times based on the amplitude of the voltage of a switching-type oxygen sensor and the time response of the sensor. The frequency of the purge, which ideally is directly related to the device capacity depletion rate, is controlled so that the device is not filled beyond the storage capacity limit.

Abstract: A method of optimizing vehicle emissions during lean engine operation is disclosed wherein an emission control device receiving engine exhaust gases is filled with one or more constituent gases of the exhaust gas to a predetermined fraction of the device storage capacity, and is then completely emptied during a subsequent purge. As the device storage capacity is substantially reduced, as indicated by an actual fill time becoming equal to or less than a predetermined minimum fill time, a device regeneration cycle is performed to attempt to restore device capacity. A programmed computer controls the fill and purge times based on the amplitude of the voltage of a switching-type oxygen sensor and the time response of the sensor. The frequency of the purge, which ideally is directly related to the device capacity depletion rate, is controlled so that the device is not filled beyond its storage capacity limit.

Abstract: A method and system for determining and controlling air/fuel ratio during engine cold start operation relies on applying a monotonically decreasing fuel pulse width modulation to the engine and synchronously measuring the effect of the modulation on related engine event periods. This effect is utilized in estimating air/fuel ratio, which is then compared to the desired air/fuel ratio. The difference between the estimated air/fuel ratio and the desired air/fuel ratio is used in controlling the air/fuel ratio to the desired air/fuel ratio.