Fuel injection control device for direct-injection engine

Patent metadata

Field	Value
Publication number	US-2018058366-A1
Application number	US-201615558847-A
Country	US
Kind code	A1
Filing date	Mar 16, 2016
Priority date	Mar 23, 2015
Publication date	Mar 1, 2018
Grant date	—

Abstract

A fuel injection valve ( 6 ) is configured such that the effective opening area of an injection port ( 61 ) increases as its lift amount increases. A fuel injection control unit (an engine control unit 100 ) injects fuel in a lift amount changing mode wherein, when fuel is injected into a combustion chamber ( 17 ) in the terminal period of the compression stroke, the lift amount of the fuel injection valve is set to a predetermined large lift amount in the earlier period of the injection period, and in the later period of the injection period following the earlier period of the injection period, the lift amount is set to a small lift amount smaller than the large lift amount and is in a range where the fuel injection speed increases.

First claim

1 . A fuel injection control device for a direct-injection engine, the fuel injection control device comprising:
an engine body having a combustion chamber defined by a ceiling portion of a cylinder head, a cylinder provided to a cylinder block, and a piston reciprocating in the cylinder; and a fuel injection controller having a fuel injection valve disposed so as to inject liquid fuel into the combustion chamber, and configured to inject the fuel into the combustion chamber at a predetermined timing, wherein the fuel injection valve is configured such that an effective opening area of an injection port through which the fuel is injected increases as a lift amount of the fuel injection valve increases, and fuel injection controller injects the fuel in a lift amount changing mode in which, when the fuel is injected into the combustion chamber in a terminal period of a compression stroke, the lift amount of the fuel injection valve is set to a predetermined large lift amount in an earlier period of an injection period, and in a later period of the injection period following the earlier period of the injection period, the lift amount is set to a small lift amount smaller than the large lift amount and is in a range where a fuel injection speed increases.

2 . The fuel injection control device of claim 1 , wherein
the fuel injection controller injects the fuel in the lift amount changing mode when the engine body is operated at a rotational speed which falls within a predetermined high rotational speed range, and injects the fuel in a mode in which the lift amount of the fuel injection valve is constant in the earlier and later periods of the injection period when the engine body is operated at a rotational speed which falls within a low rotational speed range where a rotational speed is lower than that in the high rotational speed range.

3 . The fuel injection control device of claim 1 , wherein
the fuel injection controller performs, when the engine body is operated at a rotational speed which falls within a predetermined high rotational speed range, a second-stage injection in which the fuel is injected in the lift amount changing mode, and before the second-stage injection, a first-stage injection in which the fuel is injected with a lift amount smaller than the large lift amount for an injection period longer than that in the second-stage injection.

4 . The fuel injection control device of claim 3 , wherein
the fuel injection controller performs, when the engine body is operated at a rotational speed which falls within a low rotational speed range where a rotational speed is lower than that in the high rotational speed range, a first-stage injection in a mode in which the lift amount of the fuel injection valve is constant in the earlier and later periods of the injection period, and after the first-stage injection, a second-stage injection in which the fuel is injected with a lift amount smaller than that in the first-stage injection for an injection period longer than that in the first-stage injection.

5 . The fuel injection control device of claim 3 , wherein
the fuel injection controller injects the fuel in the lift amount changing mode in the terminal period of the compression stroke when the engine body is operated with a load which falls within a low load range where a load is lower than a predetermined load at a rotational speed which falls within the high rotational speed range, and performs, when the engine body is operated with a load which falls within a high load range where a load is higher than that in the low load range at a rotational speed which falls within the high rotational speed range, a second-stage injection in which the fuel is injected in the lift amount changing mode, and before the second-stage injection, a first-stage injection in which the fuel is injected with a lift amount smaller than the large lift amount for an injection period longer than that in the second-stage injection.

6 . The fuel injection control device of claim 4 , wherein
the fuel injection controller injects the fuel in the lift amount changing mode in the terminal period of the compression stroke when the engine body is operated with a load which falls within a low load range where a load is lower than a predetermined load at a rotational speed which falls within the high rotational speed range, and performs, when the engine body is operated with a load which falls within a high load range where a load is higher than that in the low load range at a rotational speed which falls within the high rotational speed range, a second-stage injection in which the fuel is injected in the lift amount changing mode, and before the second-stage injection, a first-stage injection in which the fuel is injected with a lift amount smaller than the large lift amount for an injection period longer than that in the second-stage injection.

Assignees

• Mazda Motor

Inventors

• Nagasawa Takeshi
• Ota Noriyuki
• Uchida Kenji
• Ono Ryohei
• Sato Kiyotaka
• Fujimoto Hidefumi

Classifications

• F02D41/2096

  for controlling piezoelectric injectors (drive and control circuit for piezoelectric devices in general H10N30/802) · CPC title

• F02D41/401

  Controlling injection timing (F02D41/402 takes precedence) · CPC title

• F02D41/3041

  with means for triggering compression ignition, e.g. spark plug · CPC title

• F02M51/0603

  using piezoelectric or magnetostrictive operating means · CPC title

• F02B17/005

  having direct injection in the combustion chamber · CPC title