Combustion phasing control for high substitution lean burn of gaseous fuels in dual fuel engine

Patent metadata

Field	Value
Publication number	US-10934966-B2
Application number	US-201916279564-A
Country	US
Kind code	B2
Filing date	Feb 19, 2019
Priority date	Feb 19, 2019
Publication date	Mar 2, 2021
Grant date	Mar 2, 2021

Abstract

A combustion control system for a dual fuel engine includes a combustion control unit structured to receive phasing data for combustion of a main charge of gaseous fuel ignited by way of pilot shots of a liquid fuel, output a pilot fueling command based on the phasing data, and output a valve timing command. The combustion control unit is further structured to vary a phasing of combustion of a main charge of a gaseous fuel ignited by pilot shots of a liquid fuel based on an adjustment to at least one of a pilot shot delivery parameter or a valve timing parameter such as intake valve closing timing from a first engine cycle to a second engine cycle. Control of the intake valve timing can be based on a main pilot shot timing error.

First claim

What is claimed is:

1. A combustion control system for a dual fuel engine comprising:
a combustion sensor structured to produce phasing data indicative of a phasing of combustion in a cylinder in the dual fuel engine;
a combustion control unit coupled to the combustion sensor, the combustion control unit being structured to:
receive phasing data for combustion of a main charge of a gaseous fuel ignited by combustion of a plurality of pilot shots of a liquid fuel in the cylinder in a first engine cycle;
output a pilot fueling command according to a pilot shot delivery parameter in a second engine cycle, based on the phasing data;
output a valve timing command according to an intake valve timing parameter in the second engine cycle;
vary a phasing of combustion of a main charge of the gaseous fuel ignited by combustion of a plurality of pilot shots of the liquid fuel in the second engine cycle, based on an adjustment to at least one of the pilot shot delivery parameter or the valve timing parameter from the first engine cycle to the second engine cycle; and
determine the pilot fueling command in a first loop calculation, and determine the valve timing command in a second loop calculation nested with the first loop calculation.

2. The combustion control system of claim 1 wherein the intake valve timing parameter includes a late closing timing.

3. The combustion control system of claim 1 wherein the combustion control unit is further structured to calculate a pilot shot error, and to output the valve timing command based on the pilot shot error.

4. The combustion control system of claim 3 wherein the pilot shot error includes a main pilot timing error based on a difference between a main pilot timing and a target timing.

5. The combustion control system of claim 1 wherein the adjustment to the pilot shot delivery parameter varies each of a main pilot shot and an early pilot shot from the first engine cycle to the second engine cycle, and includes at least one of a pilot shot timing, a pilot shot quantity, or a pilot shot-to-shot fuel split.

6. The combustion control system of claim 5 wherein the pilot shot delivery parameter includes a main pilot shot timing and a pilot shot-to-shot fuel split between a main pilot shot and an early pilot shot.

7. The combustion control system of claim 6 wherein an early pilot shot quantity is mapped to the main pilot shot timing.

8. The combustion control system of claim 1 wherein the first loop calculation is a faster loop calculation, and the second loop calculation is a slower loop calculation.

9. A dual fuel internal combustion engine system comprising:
an engine housing having a cylinder and an intake conduit formed therein;
an intake valve movable between an open position and a closed position to fluidly connect and disconnect the cylinder with the intake conduit;
a gaseous fuel admission valve coupled with the engine housing and structured to admit a gaseous fuel for combustion in the cylinder;
an electronically controlled variable valve actuator coupled with the intake valve and structured to position the intake valve according to a valve timing parameter;
at least one electronically controlled liquid fuel injector structured to directly inject a liquid fuel into the cylinder in a main pilot shot and an early pilot shot, according to a pilot shot delivery parameter; and
a combustion control unit structured to:
receive phasing data for combustion of a main charge of a gaseous fuel ignited by combustion of a plurality of pilot shots of a liquid fuel in the cylinder in a first engine cycle;
adjust at least one of the pilot shot delivery parameter or the valve timing parameter from the first engine cycle to a second engine cycle;
vary a phasing of combustion of a main charge of the gaseous fuel ignited by combustion of a plurality of pilot shots of the liquid fuel in the second engine cycle, based on the adjustment to the at least one of the pilot shot delivery parameter or the valve timing parameter;
calculate a main pilot timing error; and
perform the adjustment to the valve timing parameter based on the main pilot timing error.

10. The dual fuel engine system of claim 9 wherein the valve timing parameter includes a late intake valve closing timing, and the combustion control unit is further structured to adjust the intake valve closing timing from the first engine cycle to the second engine cycle.

11. The dual fuel engine system of claim 10 further comprising an air-fuel-ratio (AFR) control element, and the combustion control unit is further structured to adjust the AFR control element based on the intake valve closing timing.

12. The dual fuel engine system of claim 10 wherein the combustion control unit is further structured to calculate the main pilot timing error based on a difference between a main pilot timing and a target timing, and to adjust the intake valve closing timing from the first engine cycle to the second engine cycle based on the main pilot timing error.

13. The dual fuel engine system of claim 9 wherein the combustion control unit is further structured to adjust the pilot shot delivery parameter from a first main pilot timing and a first shot-to-shot fuel split in the first engine cycle to a second main pilot timing and a second shot-to-shot fuel split in the second engine cycle, based on the phasing data.

14. A method of operating a dual fuel internal combustion engine system comprising:
producing phasing data indicative of a phasing of combustion of a main charge of a gaseous fuel ignited in a dual fuel engine by combustion of a plurality of directly injected pilot shots of a liquid fuel;
adjusting a pilot shot delivery parameter based on the phasing data;
varying an in-cylinder temperature in the dual fuel engine based on the adjustment to the pilot shot delivery parameter; and
varying a phasing of combustion of another main charge of the gaseous fuel ignited by way of a plurality of pilot shots of the liquid fuel based on the varying of the in-cylinder temperature.

15. The method of claim 14 wherein the adjusting of the pilot shot delivery parameter based on the phasing data includes advancing or retarding a main pilot shot timing.

16. The method of claim 15 wherein the varying of the in-cylinder temperature includes varying the in-cylinder temperature in response to an adjustment to an intake valve closing timing.

17. The method of claim 15 further comprising outputting a valve timing command to adjust the intake valve closing timing from a first late closing timing to a second late closing timing.

18. The method of claim 17 wherein the second late closing timing is from 60° to 50° before a top dead center position of a piston in the dual fuel engine.

19. The method of claim 18 wherein the adjustment to the pilot fuel delivery parameter and the adjustment to the intake valve closing timing occur according to different time scales.

Assignees

• Caterpillar Inc

Inventors

• Anders Jonathan W
• Rasmussen Jason Jon
• John Bobby

Classifications

• F02D13/0223

  Variable control of the intake valves only · CPC title

• F02D35/028

  by determining the combustion timing or phasing · CPC title

• F02D41/0025

  Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures · CPC title

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F02D41/40

  with means for controlling injection timing or duration · CPC title