초록 ▼

A system for controlling engine air/fuel ratio includes an engine, a compressor having an inlet receiving air. The compressor discharges air to the engine intake. A recirculation path is provided from the compressor discharge to the compressor inlet. A controllable valve is located along the recircu

A system for controlling engine air/fuel ratio includes an engine, a compressor having an inlet receiving air. The compressor discharges air to the engine intake. A recirculation path is provided from the compressor discharge to the compressor inlet. A controllable valve is located along the recirculation path. A controller is programmed to control the valve to vary the air flow to the engine intake, thereby controlling the air/fuel ratio. Various applications for the compressor recirculation arrangement are possible.

대표청구항 ▼

What is claimed is: 1. A method for controlling engine air/fuel ratio wherein an engine includes a plurality of cylinders fed by fuel injectors, an intake, and an exhaust, a compressor has an inlet receiving air, the compressor discharging air to the engine intake, the method comprising: providing

What is claimed is: 1. A method for controlling engine air/fuel ratio wherein an engine includes a plurality of cylinders fed by fuel injectors, an intake, and an exhaust, a compressor has an inlet receiving air, the compressor discharging air to the engine intake, the method comprising: providing a recirculation path extending from the compressor discharge to the compressor inlet, wherein a controllable valve is located along the recirculation path; controlling the valve to vary the air flow to the engine intake, thereby controlling the air/fuel ratio; wherein a lean NOx trap receives the engine exhaust, the lean NOx trap requiring a rich fuel mixture for regeneration; and periodically regenerating the lean NOx trap by controlling the valve to reduce the air/fuel ratio. 2. A method for controlling engine air/fuel ratio wherein an engine includes a plurality of cylinders fed by fuel injectors, an intake, and an exhaust, a compressor has an inlet receiving air, the compressor discharging air to the engine intake, the method comprising: providing a recirculation path extending from the compressor discharge to the compressor inlet, wherein a controllable valve is located along the recirculation path; controlling the valve to vary the air flow to the engine intake, thereby controlling the air/fuel ratio; wherein a diesel particulate filter receives the engine exhaust, the diesel particulate filter requiring a high temperature for regeneration; and periodically regenerating the diesel particulate filter by controlling the valve to reduce the air/fuel ratio, thereby increasing exhaust temperature. 3. A method for controlling engine air/fuel ratio wherein an engine includes a plurality of cylinders fed by fuel injectors, an intake, and an exhaust, a compressor has an inlet receiving air, the compressor discharging air to the engine intake, the method comprising: providing a recirculation path extending from the compressor discharge to the compressor inlet, wherein a controllable valve is located along the recirculation path; controlling the valve to vary the air flow to the engine intake, thereby controlling the air/fuel ratio; wherein a diesel oxidation catalyst receives the engine exhaust; and controlling the valve to reduce air/fuel ratio, thereby increasing exhaust temperature and affecting the diesel oxidation catalyst. 4. The method of claim 3 wherein the valve is controlled so as to increase exhaust temperature for more rapid catalyst light off. 5. The method of claim 3 wherein the valve is controlled so as to increase exhaust temperature to a range where catalyst efficiency is higher. 6. A system for controlling engine air/fuel ratio, the system comprising: an engine including a plurality of cylinders fed by fuel injectors, an intake, and an exhaust; a compressor having an inlet receiving air, the compressor discharging air to the engine intake; a recirculation path from the compressor discharge to the compressor inlet; a controllable valve along the recirculation path; a controller programmed to control the valve to vary the air flow to the engine intake, thereby controlling the air/fuel ratio; a lean NOx trap receiving the engine exhaust, the lean NOx trap requiring a rich fuel mixture for regeneration; and wherein the controller is programmed to periodically regenerate the lean NOx trap by controlling the valve to reduce the air/fuel ratio. 7. A system for controlling engine air/fuel ratio, the system comprising: an engine including a plurality of cylinders fed by fuel injectors, an intake, and an exhaust; a compressor having an inlet receiving air, the compressor discharging air to the engine intake; a recirculation path from the compressor discharge to the compressor inlet; a controllable valve along the recirculation path; a controller programmed to control the valve to vary the air flow to the engine intake, thereby controlling the air/fuel ratio; a diesel particulate filter receiving the engine exhaust, the diesel particulate filter requiring a high temperature for regeneration; and wherein the controller is programmed to periodically regenerate the diesel particulate filter by controlling the valve to reduce the air/fuel ratio, thereby increasing exhaust temperature. 8. A system for controlling engine air/fuel ratio, the system comprising: an engine including a plurality of cylinders fed by fuel injectors, an intake, and an exhaust; a compressor having an inlet receiving air, the compressor discharging air to the engine intake; a recirculation path from the compressor discharge to the compressor inlet; a controllable valve along the recirculation path; a controller programmed to control the valve to vary the air flow to the engine intake, thereby controlling the air/fuel ratio; a diesel oxidation catalyst receiving the engine exhaust; and wherein the controller is programmed to control the valve to reduce air/fuel ratio, thereby increasing exhaust temperature and affecting the diesel oxidation catalyst. 9. The system of claim 8 wherein the valve is controlled so as to increase exhaust temperature for more rapid catalyst light off. 10. The system of claim 8 wherein the valve is controlled so as to increase exhaust temperature to a range where catalyst efficiency is higher.