Method and system for engine cold-start control

Patent metadata

Field	Value
Publication number	US-2016356228-A1
Application number	US-201514733196-A
Country	US
Kind code	A1
Filing date	Jun 8, 2015
Priority date	Jun 8, 2015
Publication date	Dec 8, 2016
Grant date	—

Abstract

Methods and systems are provided for improving engine start roughness. In one example, a method for reducing engine start NVH includes operating the engine with a split fuel injection while advancing injection timing as engine coolant temperature increases. The method allows for a smoother engine start while also reducing false misfire incidences.

First claim

1 . A method for an engine, comprising:
starting an engine with fuel delivered as a split injection; and adjusting a fuel injection timing based on engine temperature, the injection timing advanced as the engine temperature at the engine starting increases.

2 . The method of claim 1 , wherein the split injection includes a first fraction of fuel direct injected earlier during a compression stroke of a combustion cycle and a second fraction of fuel direct injected later during the compression stroke of the combustion cycle.

3 . The method of claim 2 , wherein the injection timing is an average injection timing of the first and second fractions.

4 . The method of claim 2 , wherein advancing the injection timing includes increasing/decreasing/maintaining a duration between injection of the first fraction and injection of the second fraction.

5 . The method of claim 1 , wherein the injection timing is advanced from an initial injection timing as the engine temperature increases, the initial injection timing based on engine speed and load.

6 . The method of claim 1 , wherein the injection timing is advanced from compression stroke TDC as the engine temperature increases.

7 . The method of claim 6 , further comprising, maintaining the fuel injection timing advanced for a number of combustion events since a first combustion event of the engine start.

8 . The method of claim 7 , further comprising, after the number of combustion events since the first combustion event, retarding the injection timing towards compression stroke TDC as engine temperature increases.

9 . The method of claim 1 , further comprising, during the starting, retarding spark timing from MBT while the injection timing is advanced.

10 . The method of claim 1 , wherein the engine starting is an engine cold-start.

11 . The method of claim 1 , wherein the engine temperature includes an engine coolant temperature at the engine start, before a first combustion event.

12 . A method for an engine, comprising:
during an engine cold-start, cranking the engine with fuel delivered as a split injection at a first injection timing; and during an engine hot-start, cranking the engine with fuel delivered as a split injection at a second injection timing, the second timing advanced relative to the first timing.

13 . The method of claim 12 , wherein during the engine cold-start, fuel is delivered as a split injection at the first injection timing for a first number of combustion events, and then, as engine coolant temperature increases, advancing fuel injection timing from the first injection timing towards the second injection timing.

14 . The method of claim 13 , wherein during the engine hot-start, fuel is delivered as a split injection at the second injection timing for a second number of combustion events, the second number smaller than the first number, and then, as engine coolant temperature increases, retarding fuel injection timing from the second injection timing towards the first injection timing.

15 . The method of claim 13 , wherein the split injection during the engine cold-start includes a first number of compression stroke direct injections, and wherein the first injection timing is an average injection timing of the first number of compression stroke direct injections, and wherein the split injection during the engine hot-start includes a second number of compression stroke direct injections, the second number smaller than the first number, and wherein the second injection timing is an average injection timing of the second number of compression stroke direct injections.

16 . The method of claim 12 , wherein the split injection during the engine cold-start includes multiple compression stroke direct injections and wherein the split injection during the hot start includes at least a compression stroke direct injection and an intake stroke direct injection.

17 . The method of claim 12 , further comprising, during the engine cold-start, cranking the engine with spark timing retarded by a larger amount, and during the engine hot-start, cranking the engine with spark timing retarded by a smaller amount.

18 . An engine system, comprising:
an engine including a cylinder; a direct injector for injecting fuel directly into the cylinder; a temperature sensor for estimating an engine coolant temperature; and a controller with computer-readable instructions stored on non-transitory memory for:
during an engine start,
for a number of combustion events since a first combustion event, operating the engine with fuel delivered as multiple compression stroke injections and with an average injection timing of the multiple compression stroke injections advanced from compression stroke TDC, an amount of injection timing advance increased as the engine coolant temperature increases.

19 . The system of claim 18 , wherein the controller includes further instructions for: after the number of combustion events, while continuing to operate the engine with fuel delivered as multiple compression stroke injections, retarding the average injection timing of the multiple compression stroke injections towards compression stroke TDC, an amount of injection timing retard increased as the engine coolant temperature increases.

20 . The system of claim 19 , wherein the controller includes further instructions for, during the number of combustion events, retarding spark timing from MBT, an amount of spark retard based on the injection timing advance, and after the number of combustion events, adjusting the amount of spark retard based on engine speed and load.

Assignees

• Ford Global Tech Llc

Inventors

• Liu Chingpo
• Dudar Aed M
• Fried Marcus William
• Reichenbach Ron

Classifications

• F02D41/064 Primary

  at cold start (F02D41/067 takes precedence) · CPC title

• F02D41/26

  using computer, e.g. microprocessor · CPC title

• F02B17/005

  having direct injection in the combustion chamber · CPC title

• Y02T10/40

  Engine management systems · CPC title

• F02P5/1506

  with particular means during starting · CPC title