Method and system for controlling engine

Patent metadata

Field	Value
Publication number	US-10570808-B2
Application number	US-201815973060-A
Country	US
Kind code	B2
Filing date	May 7, 2018
Priority date	May 23, 2017
Publication date	Feb 25, 2020
Grant date	Feb 25, 2020

Abstract

A control system of an engine is provided, which includes a piston formed with a cavity and configured to reciprocate in a cylinder along a center axis of the cylinder, and a fuel injector disposed facing a top surface of the piston and configured to inject fuel along an injection axis. When the piston is located near a top dead center of compression stroke, the fuel injector performs a first injection so that the fuel flows from the fuel injector toward the cavity along the injection axis, collides with an inner surface of the cavity, then flows back toward the fuel injector along the inner surface of the cavity from a position offset from the injection axis. The fuel injector performs a second injection toward the cavity at a timing after the first injection and at which the fuel of the first injection flows back.

First claim

The invention claimed is:

1. A control system of an engine, comprising:
a piston configured to reciprocate in a cylinder along a center axis of the cylinder and formed with a cavity with a center at the center axis on a crown surface of the piston;
a fuel injector disposed facing a top surface of the piston and configured to inject fuel along an injection axis; and
a processor operatively coupled to the fuel injector, wherein
an inner surface of the cavity includes, in a cross-section including the center axis of the cylinder:
a raised center portion bulging toward the fuel injector as well as bulging larger toward the center of the cavity, the raised center portion formed with a first sloping portion extending outward from the center axis;
a bulging portion formed with a second sloping portion extending inward toward the raised center portion so as to slope toward the center axis in a radial direction of the piston, and formed with an arc formed continuously from the second sloping portion to concave radially inward toward the center axis when viewed in the cross-section including the center axis of the cylinder; and
a lip portion formed between the bulging portion and an opening edge of the cavity and formed to convex radially inward when viewed in the cross-section including the center axis of the cylinder,

the first sloping portion of the raised center portion and the second sloping portion of the bulging portion are integrally formed as only continuously curving and linear portions,
when the piston is located near a top dead center of compression stroke, the processor is configured to cause the fuel injector to perform a first injection so that the fuel flows from the fuel injector toward an upper portion of the bulging portion along the injection axis; collides with the inner surface of the cavity; then flows back toward the fuel injector along the inner surface of the cavity, from a position offset from the injection axis, and
the processor is configured to cause the fuel injector to perform a second injection toward the cavity at an injection start timing during an expansion stroke after the first injection, and at which the fuel of the first injection flows back.

2. The control system of claim 1 , wherein
the fuel injected in the first injection flows along the raised center portion from the bulging portion of the cavity to turn back toward the fuel injector from the position offset from the injection axis, the position being offset from the injection axis in a descending direction of the piston.

3. A control system of an engine, comprising:
a piston configured to reciprocate in a cylinder along a center axis of the cylinder and formed with a cavity with a center at the center axis on a crown surface of the piston;
a fuel injector disposed facing a top surface of the piston and configured to inject fuel from a nozzle port; and
a processor operatively coupled to the fuel injector, wherein an inner surface of the cavity includes, in a cross-section including the center axis of the cylinder:
a raised center portion bulging toward the fuel injector as well as bulging larger toward the center of the cavity, the raised center portion formed with a first sloping portion extending outward from the center axis;
a bulging portion formed with a second sloping portion extending inward toward the raised center portion so as to slope toward the center axis in a radial direction of the piston, and formed with an arc formed continuously from the second sloping portion to concave radially inward toward the center axis when viewed in the cross-section including the center axis of the cylinder; and
a lip portion formed between the bulging portion and an opening edge of the cavity and formed to convex radially inward when viewed in the cross-section including the center axis of the cylinder,
the first sloping portion of the raised center portion and the second sloping portion of the bulging portion are integrally formed as only continuously curving and linear portions,
a nozzle port center line that is an extension of a center of the nozzle port of the fuel injector intersects the bulging portion when the piston is located at one of a top dead center of compression stroke and a given position near the top dead center of the compression stroke, and
the processor is configured to cause the fuel injector to perform a main injection toward the bulging portion of the cavity at a first injection start timing when the piston is located near the top dead center of the compression stroke, and further cause the fuel injector to perform a second injection at a second injection start timing when the nozzle port center line intersects the bulging portion during an expansion stroke after a given interval from the end of the main injection.

4. The control system of claim 3 , further comprising a turbocharger configured to increase intake air pressure of the engine as an engine speed increases,
wherein the processor is configured to cause the fuel injector to perform the second injection at a shorter interval as the engine speed increases.

5. The control system of claim 3 , further comprising a sensor configured to detect a parameter relating to an intake air pressure of the engine,
wherein the processor is configured to cause the fuel injector to perform the second injection at a shorter interval as the intake air pressure increases.

6. The control system of claim 3 , wherein the processor is configured to cause the fuel injector to perform the second injection at a shorter interval as a fuel injection amount of the main injection increases.

7. The control system of claim 3 , wherein, when the engine is operating within a first range, the processor is configured to cause the fuel injector to perform the second injection at the second injection start timing, and when the engine is operating within a second range in which one of an engine load and an engine speed is lower than in the first range, the processor is configured to cause the fuel injector to extend the interval and perform the second injection at a third injection start timing at which at least a portion of the fuel reaches outside of the cavity.

8. A method of controlling an engine,
the engine comprising:
a piston formed with a cavity with a center at a center axis of a cylinder on a crown surface of the piston and configured to reciprocate in the cylinder along the center axis of the cylinder,
an inner surface of the cavity including, in a cross section including the center axis of the cylinder:
a raised center portion bulging toward a fuel injector as well as bulging larger toward the center of the cavity, the raised center portion formed with a first sloping portion extending outward from the center axis;
a bulging portion formed with a second sloping portion extending inward toward the raised center portion so as to slope toward the center axis in a radial direction of the piston, and formed with an arc formed continuously from the second sloping portion to concave radially inward toward the center axis when viewed in the cross-section including the center axis of the cylinder; and
a lip portion formed between the bulging portion and an opening edge of the cavity and formed to convex radially inward when viewed in the cross-section including the center axis of the cylinder,

the fuel injector disposed facing a top surface of the piston and configured to inject fuel from a nozzle port,
a nozzle port center line that is an extension of a center of the nozzle port of the fuel injector intersecting the bulging portion when the piston is located at one of a top dead center of compression stroke and a given position near the top dead center of the compression stroke;
the first sloping portion

Assignees

• Mazda Motor

Inventors

• Fukuda Daisuke
• Taguchi Akira
• Minamoto Hiroshi
• Shirahashi Naotoshi
• Kato Yudai
• Kakuda Yoshie
• Sagane Yasuyuki
• Kim Sangkyu
• Shimo Daisuke
• Hirabayashi Kazunori

Classifications

• F02B23/0651

  the fuel spray impinging on reflecting surfaces or being specially guided throughout the combustion space · CPC title

• F02D41/401

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

• F02D41/402 Primary

  Multiple injections · CPC title

• F02B23/0672 Primary

  Omega-piston bowl, i.e. the combustion space having a central projection pointing towards the cylinder head and the surrounding wall being inclined towards the cylinder center axis (the surrounding wall being exactly vertical F02B23/0696) · CPC title

• F02B23/0645

  Details related to the fuel injector or the fuel spray · CPC title