TORQUE CONTROL STRATEGY FOR A DIESEL ENGINE DURING LEAN-RICH MODULATION USING INDEPENDENT FUEL INJECTION MAPS

• US 20060005805A1
• Filed: 07/12/2004
• Published: 01/12/2006
• Est. Priority Date: 07/12/2004
• Status: Active Grant

• Current Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Original Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Inventors: Liu, Zhengbai, Wei, Puning
• Granted Patent: US 6,990,951 B1
• Time in Patent Office: Days
• US Class Current: 123/299
• CPC Class Codes: F02D 2250/21 during a transition between engine operation modes or states
• CPC Class Codes: F02D 41/0007 for control of turbo-charged or super-charged engines control of the pumps per se F02B37/12
• CPC Class Codes: F02D 41/0077 Control of the EGR valve or actuator, e.g. duty cycle, closed loop control of position EGR valve position sensor F02M26/48
• CPC Class Codes: F02D 41/0275 the exhaust gas treating apparatus being a NOx trap or adsorbent
• CPC Class Codes: F02D 41/307 to avoid torque shocks

Abstract

An engine (20) and an engine control strategy (FIGS. 2 and 3) for lean-to-rich transitions, such transitions being useful for various purposes, one of which is purging, or regenerating, a NOx adsorber (36) in the engine exhaust system.

Claims

1. A control strategy for lean-to-rich modulation of an internal combustion engine comprising:

with the engine running lean at a particular speed, causing the engine to transition from running lean to running rich while striving to maintain a desired engine torque at that particular speed by

a) processing data values for engine speed and desired engine torque to develop a data value for desired mass airflow into the engine and a data value for desired air-fuel ratio for rich running,

b) processing the data value for desired mass airflow into the engine, a data value for actual mass airflow into the engine, and a data value for actual air-fuel ratio to develop a data value for quantity of engine fueling,

c) processing the data value for quantity of engine fueling and other data relevant to a determination of the timing of introduction of that quantity of engine fueling into the engine during an engine cycle that will cause the engine to run rich while striving to maintain desired engine torque at the particular engine speed, to develop a data value for that timing,

d) forcing intake mass airflow toward that desired mass airflow, and

e) fueling the engine with that quantity of engine fueling at that timing.

2. A control strategy as set forth in claim 1 in which step c) comprises:

processing the data value for quantity of engine fueling, the data value for engine speed, the data value for actual mass airflow into the engine, and the data value for desired engine torque to develop the data value for the timing of introduction of that quantity of engine fueling into the engine during an engine cycle that will cause the engine to run rich while striving to maintain desired engine torque at the particular engine speed.

3. A control strategy as set forth in claim 1 wherein step d) comprises:

forcing intake mass airflow toward that desired mass airflow by control of one or more components of an intake system of the engine through which the airflow enters the engine.

4. A control strategy as set forth in claim 3 wherein the step of forcing intake mass airflow toward that desired mass airflow by control of one or more components of an intake system of the engine through which the airflow enters the engine comprises control of exhaust gas recirculation (EGR).

5. A control strategy as set forth in claim 3 wherein the step of forcing intake mass flow toward that desired mass airflow by control of one or more components of an intake system of the engine through which the airflow enters the engine comprises control of a throttle valve through which fresh intake air enters the intake system.

6. A control strategy as set forth in claim 3 wherein the step of forcing intake mass airflow toward that desired mass airflow by control of one or more components of an intake system of the engine through which the airflow enters the engine comprises controlling the duty cycle of a signal that controls a turbocharger having a turbine in an exhaust system of the engine and a compressor in the intake system.

7. A control strategy as set forth in claim 3 wherein the step of forcing intake mass airflow toward that desired mass airflow by control of one or more components of an intake system of the engine through which the airflow enters the engine comprises controlling one or more component by closed-loop control for certain combinations of engine speed and torque, by open-loop control for certain other combinations of engine speed and torque, and by varying degrees of both open- and closed-loop control for still other combinations of engine speed and torque.

8. A strategy for regenerating a NOx adsorber in an exhaust system of an internal combustion engine by conditioning engine operation to generate excess CO for inducing regeneration, the strategy comprising:

with the engine running lean at a particular speed, generating excess CO by causing the engine to transition from running lean to running rich while striving to maintain a desired engine torque at that particular speed by

a) processing data values for engine speed and desired engine torque to develop a data value for desired mass airflow into the engine and a data value for desired air-fuel ratio for rich running,

b) processing the data value for desired mass airflow into the engine, a data value for actual mass airflow into the engine, and a data value for actual air-fuel ratio to develop a data value for quantity of engine fueling,

c) processing the data value for quantity of engine fueling and other data relevant to a determination of the timing of introduction of that quantity of engine fueling into the engine during an engine cycle that will cause the engine to run rich while striving to maintain desired engine torque at the particular engine speed, to develop a data value for that timing,

d) forcing intake mass airflow toward that desired mass airflow, and

e) fueling the engine with that quantity of engine fueling at that timing.

9. A strategy as set forth in claim 8 in which step c) comprises:

processing the data value for quantity of engine fueling, the data value for engine speed, the data value for actual mass airflow into the engine, and the data value for desired engine torque to develop the data value for the timing of introduction of that quantity of engine fueling into the engine during an engine cycle that will cause the engine to run rich while striving to maintain desired engine torque at the particular engine speed.

10. A strategy as set forth in claim 8 wherein step d) comprises:

forcing intake mass airflow toward that desired mass airflow by control of one or more components of an intake system of the engine through which the airflow enters the engine.

11. A strategy for regenerating a NOx adsorber in an exhaust system of an internal combustion engine by conditioning engine operation to generate excess CO for inducing regeneration, the strategy comprising:

with the engine running lean and delivering a certain torque at a certain speed, controlling at least one of airflow entering the engine through an intake system of the engine and fueling of the engine to substantially maintain that torque and speed while significantly decreasing the air-fuel ratio in the process to generate excess CO for regenerating the NOx adsorber.

12. A strategy as set forth in claim 11 wherein both airflow entering the engine through the intake system and fueling of the engine are controlled to substantially maintain torque and speed while significantly decreasing the air-fuel ratio in the process to generate excess CO for regenerating the NOx adsorber.

13. An internal combustion engine comprising:

a) a fueling system for fueling the engine in accordance with a data value for desired engine fueling;

b) an intake system through which airflow enters the engine, and

c) a control system for processing various data to develop data for control of various engine functions including data values for desired engine fueling, for desired mass airflow into the engine, and for desired air-fuel ratio, wherein the control system comprises a control strategy

i) for causing the engine to transition from running lean to running rich while striving to maintain engine torque at a particular engine speed by

ii) processing data values for engine speed and desired engine torque to develop a data value for desired mass airflow into the engine and a data value for desired air-fuel ratio for rich running,

iii) processing the data value for desired mass airflow into the engine, a data value for actual mass airflow into the engine, and a data value for actual air-fuel ratio to develop a data value for quantity of engine fueling,

iv) processing the data value for quantity of engine fueling and other data relevant to a determination of the timing of introduction of that quantity of engine fueling into the engine during an engine cycle that will cause the engine to run rich while striving to maintain desired engine torque at the particular engine speed, to develop a data value for that timing,

v) forcing intake mass airflow toward that desired mass airflow, and

vi) fueling the engine with that quantity of engine fueling at that timing.

14. An engine as set forth in claim 13 in which the portion of the control strategy for processing the data value for quantity of engine fueling and other data relevant to a determination of the timing of introduction of that quantity of engine fueling into the engine during an engine cycle that will cause the engine to run rich while striving to maintain desired engine torque at the particular engine speed to develop a data value for that timing comprises strategy for processing the data value for quantity of engine fueling, the data value for engine speed, the data value for actual mass airflow into the engine, and the data value for desired engine torque to develop the data value for the timing of introduction of that quantity of engine fueling into the engine during an engine cycle that will cause the engine to run rich while striving to maintain desired engine torque at the particular engine speed.

15. An engine as set forth in claim 13 in which the portion of the control strategy for forcing intake mass airflow toward that desired mass airflow comprises strategy for forcing intake mass airflow toward that desired mass airflow by closed-loop control of one or more components of an intake system of the engine through which mass airflow enters the engine.

16. An engine as set forth in claim 15 wherein the one or more components of the intake system comprise one or more of an exhaust gas recirculation (EGR) valve that control recirculation of exhaust gas from an exhaust system of the engine to the intake system, a throttle valve through which fresh intake air enters the intake system, and a turbocharger having a turbine in an exhaust system and a compressor in the intake system.

17. An engine as set forth in claim 15 wherein the one or more components is controlled by closed-loop control for certain combinations of engine speed and torque, by open-loop control for certain other combinations of engine speed and torque, and by varying degrees of both open- and closed-loop control for still other combinations of engine speed and torque.

18. An internal combustion engine comprising:

a) a fueling system for fueling the engine in accordance with a data value for desired engine fueling;

b) an intake system through which airflow enters the engine;

c) a NOx adsorber in an exhaust system of the engine; and

d) an engine control system that at times conditions engine operation to generate excess CO for inducing regeneration of the NOx absorber and that comprises a strategy for generating excess CO by causing the engine to transition from running lean at a particular speed to running rich while striving to maintain a desired engine torque at that particular speed by

i) processing data values for engine speed and desired engine torque to develop a data value for desired mass airflow into the engine and a data value for desired air-fuel ratio for rich running,

ii) processing the data value for desired mass airflow into the engine, a data value for actual mass airflow into the engine, and a data value for actual air-fuel ratio to develop a data value for quantity of engine fueling,

ii) processing the data value for quantity of engine fueling and other data relevant to a determination of the timing of introduction of that quantity of engine fueling into the engine during an engine cycle that will cause the engine to run rich while striving to maintain desired engine torque at the particular engine speed, to develop a data value for that timing,

iv) forcing intake mass airflow toward that desired mass airflow, and

v) fueling the engine with that quantity of engine fueling at that timing.

19. An engine as set forth in claim 18 in which step iii) comprises:

processing the data value for quantity of engine fueling, the data value for engine speed, the data value for actual mass airflow into the engine, and the data value for desired engine torque to develop the data value for the timing of introduction of that quantity of engine fueling into the engine during an engine cycle that will cause the engine to ran rich while striving to maintain desired engine torque at the particular engine speed.

20. An engine as set forth in claim 18 wherein step iv) comprises:

forcing intake mass airflow toward that desired mass airflow by control of one or more components associated with the intake system.

21. An internal combustion engine comprising a control system endowed with a strategy for regenerating a NOx adsorber in an exhaust system of the engine by conditioning engine operation to generate excess CO for inducing regeneration, the control system comprising a processor that develops data for controlling at least one of airflow entering the engine through an intake system of the engine and fueling of the engine by a fueling system of the engine to substantially maintain a particular torque and speed while significantly decreasing the air-fuel ratio in the process to generate excess CO for regenerating the NOx adsorber.

22. An engine as set forth in claim 21 wherein the processor develops data for controlling both airflow entering the engine through the intake system and fueling of the engine to substantially maintain the particular torque and speed while significantly decreasing the air-fuel ratio in the process to generate excess CO for regenerating the NOx adsorber