Dual fuel engine combustion control strategy optimizing pilot shot quantities

Patent metadata

Field	Value
Publication number	US-12516638-B2
Application number	US-202418602362-A
Country	US
Kind code	B2
Filing date	Mar 12, 2024
Priority date	Mar 12, 2024
Publication date	Jan 6, 2026
Grant date	Jan 6, 2026

Abstract

An engine system operating and control strategy includes autoigniting a directly injected pilot fuel to ignite a primary fuel in a cylinder in a first engine cycle. The strategy further includes comparing data indicative of a heat release in a cylinder in the first engine cycle to phasing error criteria for an earlier pilot shot of the pilot fuel and a later shot of the pilot fuel. A quantity of one or more pilot shots in a subsequent engine cycle is varied, based on the comparison. Pilot shot quantity can be varied closed loop to obtain desired combustion phasing characteristics, such as when a characteristic of a primary fuel is changed during operation. Related apparatus and control logic is also disclosed.

First claim

What is claimed is:

1 . A method of operating an engine system comprising:
directly injecting an earlier shot and a later shot of a pilot fuel into a cylinder in an engine in a first engine cycle; autoigniting the pilot fuel to ignite a primary fuel in the cylinder in the first engine cycle; receiving data indicative of a heat release in the cylinder in the first engine cycle; comparing the data to a first phasing error criterion for the earlier shot and to a second phasing error criterion for the later shot that is different from the first phasing error criterion; varying a quantity of an earlier shot of the pilot fuel injected in a subsequent engine cycle, based on the comparing the data to the first phasing error criterion, and varying the quantity of a later pilot shot of the pilot fuel injected in the subsequent engine cycle, based on the comparing the data to the second phasing error criterion; and autoigniting the pilot fuel to ignite the primary fuel in the cylinder in the subsequent engine cycle.

2 . The method of claim 1 wherein the receiving data includes receiving data indicative of a heat release rate (HRR), produced via an in-cylinder pressure sensor.

3 . The method of claim 2 wherein each of the first phasing error criterion and the second phasing error criterion includes a different HRR-based limit, and the varying the quantity includes increasing the quantity so as to vary at least one of a timing parameter or an amplitude parameter of an HRR curve in the subsequent engine cycle.

4 . The method of claim 1 wherein the varying the quantity includes varying the quantity of the earlier shot according to a first metric and varying the quantity of the second shot according to a second metric different from the first metric.

5 . The method of claim 4 wherein the varying includes closed-loop varying, and each of the first metric and the second metric includes a timing-based fuel burned metric.

6 . The method of claim 5 wherein the first metric includes a crank angle metric for a relatively larger fuel burned amount, and the second metric includes a crank angle metric for a relatively smaller fuel burned amount.

7 . The method of claim 1 wherein the pilot fuel includes a compression-ignition liquid fuel, and the primary fuel includes a gaseous fuel.

8 . The method of claim 7 further comprising varying a characteristic of the primary fuel between a preceding engine cycle and the first engine cycle, and wherein the varying the quantity compensates for the varying the characteristic of the primary fuel.

9 . An engine system comprising:
an engine having a cylinder formed therein, and a piston movable in the cylinder; a direct fuel injector arranged to directly inject shots of a pilot fuel into the cylinder in a first engine cycle and a subsequent engine cycle; a primary fuel admission valve for admitting a primary fuel for combustion in the cylinder based on autoignition of the pilot fuel in the first engine cycle and the subsequent engine cycle; a fuel control system including a sensor structured to produce data indicative of a heat release in the cylinder, and a fueling control unit; the fueling control unit being structured to:
compare the data to phasing error criteria for an earlier shot of the pilot fuel and to different phasing error criteria for a later shot of the pilot fuel, in the first engine cycle; and
vary a quantity of an earlier shot of the pilot fuel in the subsequent engine cycle, based on the comparing the data to the phasing error criteria, and vary a quantify of a later shot of the pilot fuel in the subsequent engine cycle, based on the comparing the data to the different phasing error criteria.

10 . The engine system of claim 9 wherein the phasing error criteria include a heat release rate (HRR)-based limit.

11 . The engine system of claim 10 wherein the fueling control unit is further structured to vary the quantity of at least one of the earlier pilot shot or the later pilot shot via increasing the quantity so as to vary at least one of a timing parameter or an amplitude parameter of an HRR curve in the subsequent engine cycle.

12 . The engine system of claim 10 wherein the phasing error criteria include a first heat release rate (HRR)-based limit and a second HRR-based limit for the earlier shot and the later shot, respectively.

13 . The engine system of claim 12 wherein the first HRR-based limit includes an HRR-based limit at a later crank angle timing, and the second HRR-based limit includes an HRR-based limit at an earlier crank angle timing.

14 . The engine system of claim 9 wherein the fueling control unit is further structured to vary the quantity according to at least one timing-based fuel burned metric.

15 . The engine system of claim 14 wherein the at least one timing-based fuel burned metric includes a first crank angle metric for the earlier shot for a relatively larger fuel burned amount, and a second metric includes a second crank angle metric for the later shot for a relatively smaller fuel burned amount.

16 . The engine system of claim 15 wherein the relatively larger fuel burned amount includes a fuel burned amount that is 50% or greater, and the relatively lesser fuel burned amount includes a fuel burned amount that is less than 50%.

17 . A dual fuel control system comprising:
a fueling control unit structured to receive data indicative of a heat release in a cylinder produced in a first engine cycle by combustion of a fuel charge including a primary fuel and a plurality of shots of an autoignited pilot fuel; the fueling control unit being further structured to compare the data to different phasing error criteria for each respective one of the plurality of autoignited shots of the directly injected pilot fuel; the fueling control unit being further structured to produce a at least one combustion phasing error signal based on the comparison of the data to the different phasing error criteria; the fueling control unit being further structured to output a first pilot fuel injection command and a second pilot fuel injection command to form a fuel charge of the primary fuel and the pilot fuel in a subsequent engine cycle; and the fueling control unit being further structured via the first pilot fuel injection command to vary a quantity of an earlier shot of the pilot fuel in the subsequent engine cycle, based on the at least one combustion phasing error signal, and via the second pilot fuel injection command to vary a quantity of a later shot of the pilot fuel, based on the at least one combustion phasing error signal.

18 . The dual fuel control system of claim 17 wherein the phasing error criteria include a heat release rate (HRR)-based limit.

19 . The dual fuel control system of claim 18 wherein the phasing error criteria include a first HRR-based limit and a second HRR-based limit specific, respectively, to the earlier shot and to the later shot of the plurality of shots in the first engine cycle.

20 . The dual fuel control system of claim 18 wherein the fueling control unit is further structured to output a plurality of pilot fuel injection commands varying a quantity of at least one shot of the pilot fuel in each of a plurality of subsequent engine cycles closed loop according to a timing-based fuel burned metric.

Assignees

• Caterpillar Inc

Inventors

• John Bobby
• Anders Jonathan W

Classifications

• F02D19/0647

  the gaseous fuel being liquefied petroleum gas [LPG], liquefied natural gas [LNG], compressed natural gas [CNG] or dimethyl ether [DME] · CPC title

• F02D19/0613

  Switch-over from one fuel to another (F02D19/081 takes precedence) · CPC title

• Y02T10/30

  Use of alternative fuels, e.g. biofuels · CPC title

• F02D19/0636

  by estimation, i.e. without using direct measurements of a corresponding sensor · CPC title

• F02D19/0649

  Liquid fuels having different boiling temperatures, volatilities, densities, viscosities, cetane or octane numbers · CPC title