Fuel injection control method and fuel injection control device for compression self-ignition engine

Patent metadata

Field	Value
Publication number	US-10012174-B2
Application number	US-201615380640-A
Country	US
Kind code	B2
Filing date	Dec 15, 2016
Priority date	Dec 24, 2015
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

The compression self-ignition engine fuel injection control device is configured to, during one combustion stroke, perform multiple fuel injections to induce multiple combustions in a cylinder. The fuel injection control device comprises a PCM ( 70 ) configured to set an interval between a pre-injection and a main injection in the multiple fuel injections, so as to allow valley regions of a curve indicative of a frequency characteristic of a combustion pressure wave generated by the multiple combustions to fall within respective ranges of a plurality of resonant frequency bands of a structure of an engine body of the engine, wherein the PCM is operable to increase the interval between the pre-injection and the main injection more largely as an engine load becomes lower at a same engine speed.

First claim

What is claimed is:

1. A fuel injection control method for a compression self-ignition engine configured to, during one combustion stroke, perform multiple fuel injections to induce multiple combustions in a cylinder, comprising
a step of setting an interval between a pre-injection and a main injection in the multiple fuel injections, so as to allow valley regions of a curve indicative of a frequency characteristic of a combustion pressure wave generated by the multiple combustions to fall within respective ranges of a plurality of resonant frequency bands of a structure of an engine body of the engine,
wherein the step of setting an interval between a pre-injection and a main injection includes a sub-step of increasing the interval between the pre-injection and the main injection more largely as an engine load becomes lower at a same engine speed.

2. The fuel injection control method as recited in claim 1 , which further comprises a step of: setting an injection timing of the main injection to a timing corresponding to a given crank angle; setting an injection timing of the pre-injection and optionally an injection timing of an after-injection in the multiple fuel injections, based on the set fuel injection interval; and controlling a fuel injection unit to perform, at the set injection timings, the pre-injection, the main injection and optionally the after-injection, respectively.

3. A fuel injection control device for a compression self-ignition engine configured to, during one combustion stroke, perform multiple fuel injections to induce multiple combustions in a cylinder, comprising
a controller configured to set an interval between a pre-injection and a main injection in the multiple fuel injections, so as to allow valley regions of a curve indicative of a frequency characteristic of a combustion pressure wave generated by the multiple combustions to fall within respective ranges of a plurality of resonant frequency bands of a structure of an engine body of the engine,
wherein the controller is operable to increase the interval between the pre-injection and the main injection more largely as an engine load becomes lower at a same engine speed.

4. The fuel injection control device as recited in claim 3 , wherein the controller is operable to fix the injection timing of the main injection, and advance an injection timing of the pre-injection more largely as the engine load becomes lower at the same engine speed.

5. The fuel injection control device as recited in claim 3 , wherein, on an assumption that an engine operating state is divided into a high load region in which the engine load is relatively high, a moderately-high load region in which the engine load is lower than that in the high load region, and a medium load region in which the engine load is lower than that in the moderately-high load region, the controller is operable, in the moderately-high load region, to increase the interval between the pre-injection and the main injection as compared to the high load region, and, in the medium load region, to increase the interval between the pre-injection and the main injection as compared to the moderately-high load region, and increase a fuel injection amount of the pre-injection as compared to the high load region and the moderately-high load region.

6. The fuel injection control device as recited in claim 3 , wherein the controller is operable to set an injection timing of the main injection to a timing corresponding to a given crank angle; set an injection timing of the pre-injection and optionally an injection timing of an after-injection in the multiple fuel injections, based on the set fuel injection interval; and control a fuel injection unit to perform, at the set injection timings, the pre-injection, the main injection and optionally the after-injection, respectively.

Assignees

• Mazda Motor

Inventors

• Shirahashi Naotoshi
• Mori Tsunehiro
• Matsubara Takeshi
• Yamamoto Takahiro
• Iwata Kiyoaki
• Nagato Kiyonori

Classifications

• F02D2200/025

  Engine noise, e.g. determined by using an acoustic sensor · CPC title

• F02D2041/288

  for performing a transformation into the frequency domain, e.g. Fourier transformation · CPC title

• F02D41/405

  with post injections · CPC title

• F02D41/403 Primary

  with pilot injections · CPC title

• F02D41/402

  Multiple injections · CPC title