SYSTEMS AND METHODS FOR ENGINE CONTROL

• US 20180320611A1
• Filed: 05/03/2017
• Published: 11/08/2018
• Est. Priority Date: 05/03/2017
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Glugla, Chris Paul
• Granted Patent: US 10,138,830 B1
• Time in Patent Office: Days
• CPC Class Codes: F02D 35/027 using knock sensors
• CPC Class Codes: F02D 37/02 one of the functions being ignition
• CPC Class Codes: F02D 41/0052 Feedback control of engine parameters, e.g. for control of air/fuel ratio or intake air amount
• CPC Class Codes: F02D 41/0072 Estimating, calculating or determining the EGR rate, amount or flow sensors in EGR systems F02M26/45
• CPC Class Codes: F02D 41/1454 the characteristics being an oxygen content or concentration or the air-fuel ratio
• CPC Class Codes: F02D 43/04 using only digital means
• CPC Class Codes: F02M 26/49 Detecting, diagnosing or indicating an abnormal function of the EGR system
• CPC Class Codes: F02M 35/1038 for temperature or pressure
• CPC Class Codes: F02P 5/045 combined with electronic control of other engine functions, e.g. fuel injection in general F02D37/02
• CPC Class Codes: F02P 5/1504 with particular means during a transient phase, e.g. acceleration, deceleration, gear change during starting F02P5/1506
• CPC Class Codes: F02P 5/1516 with means relating to exhaust gas recirculation, e.g. turbo
• CPC Class Codes: F02P 5/152 dependent on pinking detecting or indicating knocks in internal-combustion engines G01L23/22
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Methods and systems are provided for adjusting spark timing and fueling in an engine in response to an indication of exhaust gas recirculation (EGR) system degradation due to a disconnected upstream hose of an EGR differential pressure sensor. In one example, a method may include, responsive to an integrated knock intensity being greater than a threshold intensity and a fuel control correction being greater than a threshold enrichment, setting an EGR rate to zero and triggering an EGR differential pressure sensor upstream hose diagnostic routine to be performed. Further, spark timing and fueling may be set for zero EGR.

Claims

1. A method, comprising:

during engine operation with a commanded amount of exhaust gas recirculation EGR, responsive to at least one of an integrated knock intensity of an engine being greater than a threshold intensity and a fuel control correction of fuel supplied to the engine being greater than a threshold enrichment, setting an EGR rate to zero.

2. The method of claim 1, wherein the integrated knock intensity is determined based on an output of a knock sensor coupled to the engine over a number of engine cycles.

3. The method of claim 1, wherein the fuel control correction is determined based on a difference between a commanded air-fuel ratio (AFR) of the engine and a measured AFR sensed via an exhaust gas oxygen sensor.

4. The method of claim 1, wherein setting the EGR rate to zero includes commanding closed an EGR valve coupled to an EGR passage from an at least partially open position to block exhaust flow from an exhaust system to an intake manifold and continuing to carry out combustion after closing the EGR valve with fueling and spark timing based on operation without EGR.

5. The method of claim 4, further comprising indicating potential EGR system degradation due to detachment of an upstream hose of an EGR differential pressure sensor coupled to the EGR passage.

6. The method of claim 4, further comprising:

adjusting a spark timing from a current spark timing based on the commanded amount of EGR to an updated spark timing for the zero EGR rate;

adjusting a fuel command from a current pulse-width based on the commanded amount of EGR to an updated pulse-width for the zero EGR rate; and

initiating a monitor for diagnosing an upstream hose of an EGR differential pressure sensor.

7. The method of claim 6, wherein the upstream hose of the EGR differential pressure sensor is fluidically coupled to the EGR passage upstream of a metered orifice.

8. The method of claim 6, wherein the updated spark timing is retarded relative to the current spark timing.

9. The method of claim 6, wherein the updated pulse-width is increased relative to the current pulse-width as a function of a cylinder air amount.

10. A method, comprising:

while operating an engine with EGR, adjusting spark responsive to an indication of knock;

responsive to the adjusted spark being retarded to a spark retard threshold, integrating knock sensor output over a number of engine cycles and determining a fuel control correction over the number of engine cycles; and

indicating degradation of an EGR system responsive to one or more of the integrated output of the knock sensor being greater than a first threshold and the fuel control correction being greater than a second threshold.

11. The method of claim 10, wherein the fuel control correction includes a fuel enrichment required to maintain an exhaust air-fuel ratio (AFR) at a target AFR while operating the engine with the EGR.

12. The method of claim 10, wherein the first threshold is a threshold integrated knock intensity of the engine operating at borderline, the first threshold based on a flow rate of the EGR and a knock history of the engine, and the second threshold is a threshold fuel enrichment based on the flow rate of the EGR and a determined air charge.

13. The method of claim 10, further comprising, in response to the indication of degradation of the EGR system, operating the engine with no EGR while retarding spark timing and increasing a fuel injection amount, the retarded spark timing and increased fuel injection amount corresponding to a zero EGR flow rate.

14. The method of claim 13, wherein operating the engine with no EGR includes fully closing an EGR valve coupling an exhaust passage of the engine to an intake manifold of the engine.

15. The method of claim 14, further comprising, responsive to the indication of degradation of the EGR system, diagnosing an upstream hose of an EGR differential pressure sensor coupled to the EGR valve.

16. The method of claim 15, wherein diagnosing the upstream hose of the EGR differential pressure sensor includes, while maintaining the EGR valve closed, measuring EGR flow through the EGR system using the EGR differential pressure sensor and indicating a disconnection of the upstream hose of the EGR differential pressure sensor in response to an output of the sensor being greater than a threshold.

17. A system, comprising:

an engine having a cylinder;

an intake manifold and an exhaust system;

an EGR system, comprising an EGR passage fluidically coupling the intake manifold to the exhaust system, the EGR passage including a restrictive orifice, an EGR valve coupled to the EGR passage, and a differential pressure sensor for sensing EGR flow, the sensor including an upstream hose coupled to the EGR passage, upstream of the restrictive orifice, and a downstream hose coupled to the EGR passage, downstream of the restrictive orifice;

a spark plug for providing spark to the cylinder;

a knock sensor;

a manifold absolute pressure (MAP) sensor coupled to the intake manifold for estimating an engine airflow;

an exhaust gas oxygen sensor coupled to the exhaust system; and

a controller configured with computer readable instructions stored on non-transitory memory for;

operating the engine with an EGR flow;

estimating a cylinder air amount based on each of the engine airflow and the EGR flow;

calculating each of a fuel command based on the cylinder air amount and a correction to the fuel command based on exhaust gas oxygen sensor output;

calculating a spark timing based in part on the EGR flow;

detecting knock based on output of the knock sensor;

retarding spark from the determined spark timing in response to knock detection; and

indicating potential disconnection of the upstream hose from at least one of the EGR passage and the differential pressure sensor responsive to each of the correction to the fuel command being greater than a threshold enrichment, an integrated output of the knock sensor being greater than a threshold intensity, and spark retard reaching a spark retard threshold.

18. The system of claim 17, wherein the controller includes further instructions for:

responsive to the indication of potential disconnection of the upstream hose, disabling the EGR system and confirming the disconnection of the upstream hose of the differential pressure sensor based on a presence of EGR flow through the EGR passage.

19. The system of claim 18, wherein disabling the EGR system further includes commanding the EGR valve fully closed and setting the EGR flow to zero.

20. The system of claim 18, wherein confirming the disconnection of the upstream hose based on the presence of EGR flow includes measuring a delta pressure across the restrictive orifice with the differential pressure sensor while the EGR valve is maintained closed and indicating disconnection of the upstream hose in response to the delta pressure being lower than a threshold.