Method and system for engine auto-ignition detection and mitigation

Patent metadata

Field	Value
Publication number	US-9915240-B2
Application number	US-201615153399-A
Country	US
Kind code	B2
Filing date	May 12, 2016
Priority date	May 12, 2016
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

A system and method for detecting and mitigating automatic ignition in a cylinder of an internal combustion engine. The method includes providing a first sensor for sensing and determining a crank angle of a crankshaft of the engine. A second sensor is provided for detecting a change in an engine vibration frequency caused by Auto Ignition (AI). The engine vibration signal of the second sensor is processed into a knock intensity signal. The knock intensity signal is indicative of the cylinder pressure and is acquired when the crank angle is between a first predetermined crank angle and a second predetermined crank angle. At least one characteristic of the knock intensity signal is determined and the at least one characteristic of the knock intensity signal is compared to at least one predetermined characteristic threshold. If the at least one characteristic of the knock intensity signal is determined to exceed the at least one predetermined characteristic threshold, then at least one auto ignition mitigating action is performed to mitigate the auto ignition event.

First claim

What is claimed is:

1. A method for detecting and mitigating auto ignition in a cylinder of an internal combustion engine, the method comprising:
providing a first sensor for sensing a crank angle of a crankshaft of the engine;
providing a second sensor for detecting a knock intensity signal in the cylinder of the engine;
determining the crank angle using the first sensor;
calculating a knock intensity signal indicative of the cylinder pressure when the crank angle is between a first predetermined crank angle and a second predetermined crank angle;
determining at least one characteristic of the knock intensity signal, wherein the at least one characteristic is an amplitude of the knock intensity signal;
comparing the at least one characteristic of the knock intensity signal to at least one predetermined characteristic;
determining if the at least one characteristic of the knock intensity signal exceeds the at least one predetermined characteristic; and
performing at least one auto ignition mitigating action when the at least one characteristic of the knock intensity signal exceeds the at least one predetermined characteristic, wherein the at least one auto ignition mitigating action is selected from the group consisting of:
(a) enriching a fuel flow to the cylinder when an engine speed is between a first predetermined engine speed threshold and a second predetermined engine speed threshold and an engine load is between a first predetermined engine load threshold and a second predetermined engine load threshold;
(b) shutting off a fuel flow into the cylinder when an engine speed is between a third predetermined engine speed threshold and a fourth predetermined engine speed threshold, and the engine load is between a third predetermined engine load threshold and a fourth predetermined engine load threshold;
(c) adjusting an air intake camshaft position when engine speed is between a fifth predetermined engine speed threshold and a sixth predetermined engine speed threshold and the engine load is between a fifth predetermined engine load threshold and a sixth predetermined engine load threshold; and
(d) preventing a short term ignition retard when engine speed is between the first predetermined engine speed threshold and a seventh predetermined engine speed threshold and the engine load is between a seventh predetermined engine load threshold and a eighth predetermined engine load threshold.

2. The method of claim 1 wherein calculating a knock intensity signal further comprises converting the engine vibration signal from an analog signal to a digital signal.

3. The method of claim 2 wherein calculating a knock intensity signal further comprises performing a Fast Fourier Transform (FFT) on the digital signal to convert the digital signal to a frequency signal.

4. The method of claim 1 wherein performing at least one auto ignition mitigating action further comprises performing at least two auto ignition mitigating actions at the same time based on engine speed and engine load.

5. A method for detecting and mitigating auto ignition in a cylinder of an internal combustion engine, the method comprising:
providing a first sensor for detecting a cylinder pressure in the cylinder of the engine;
calculating a knock intensity signal indicative of the cylinder pressure during an engine crank cycle;
determining at least one characteristic of the knock intensity signal;
comparing the at least one characteristic of the knock intensity signal to at least one predetermined characteristic, wherein the at least one characteristic is an amplitude of the knock intensity signal;
determining if the at least one characteristic of the knock intensity signal exceeds the at least one predetermined characteristic; and
performing at least one auto ignition mitigating action when the at least one characteristic of the knock intensity signal exceeds the at least one predetermined characteristic, wherein the at least one auto ignition mitigating action is selected from the group consisting of:
(a) enriching a fuel flow to the cylinder when an engine speed is between a first predetermined engine speed threshold and a second predetermined engine speed threshold and an engine load is between a first predetermined engine load threshold and a second predetermined engine load threshold;
(b) shutting off a fuel flow into the cylinder when an engine speed is between a third predetermined engine speed threshold and a fourth predetermined engine speed threshold, and the engine load is between a third predetermined engine load threshold and a fourth predetermined engine load threshold;
(c) adjusting an air intake camshaft position when engine speed is between a fifth predetermined engine speed threshold and a sixth predetermined engine speed threshold and the engine load is between a fifth predetermined engine load threshold and a sixth predetermined engine load threshold; and
(d) preventing a short term ignition retard when engine speed is between the first predetermined engine speed threshold and a seventh predetermined engine speed threshold and the engine load is between a seventh predetermined engine load threshold and a eighth predetermined engine load threshold.

6. The method of claim 5 further comprising providing a second sensor for measuring a crank angle of a crankshaft of the engine.

7. The method of claim 6 wherein calculating the knock intensity signal further comprises reading the engine vibration signal when the measured crank angle is between a first predetermined crank angle and a second predetermined crank angle.

8. The method of claim 6 wherein calculating the knock intensity signal further comprises reading the engine vibration signal when the measured crank angle is between a third predetermined crank angle and a fourth predetermined crank angle.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Sawdon Craig M
• Ferch Eric B
• Mcmillan Kathryn W

Classifications

• F02D41/1497 Primary

  With detection of the mechanical response of the engine · CPC title

• F02D35/023

  by determining the cylinder pressure · CPC title

• F02D37/02

  one of the functions being ignition · CPC title

• F02D35/027

  using knock sensors · CPC title

• F02D41/3005

  Details not otherwise provided for · CPC title