Combustion chamber structure for engines

Patent metadata

Field	Value
Publication number	US-11118499-B2
Application number	US-201816618041-A
Country	US
Kind code	B2
Filing date	May 22, 2018
Priority date	Jun 2, 2017
Publication date	Sep 14, 2021
Grant date	Sep 14, 2021

Abstract

A structure of a combustion chamber for an engine includes a crown surface of a piston, a combustion chamber ceiling surface formed on a cylinder head, an injector and an ignition plug provided on the combustion chamber ceiling surface, and an intake opening and an exhaust opening opened in the combustion chamber ceiling surface. A side where the intake opening is opened is defined as an intake port side, and a side where the exhaust opening is opened is defined as an exhaust port side, with respect to a position, as a reference, where an ignition portion of the ignition plug is disposed in a plan view from one side in a cylinder axis direction, the injector is configured to inject fuel toward the exhaust port side, and a reverse squish flow generation portion, which draws an air-fuel mixture toward the intake port side, is provided in the combustion chamber.

First claim

The invention claimed is:

1. A spark ignited engine, comprising:
a crown surface of a piston;
a combustion chamber ceiling surface formed on a cylinder head;
an injector and an ignition plug provided on the combustion chamber ceiling surface; and
an intake opening and an exhaust opening opened in the combustion chamber ceiling surface, wherein
the ignition plug is ignited when the piston is in an expansion stroke,
a side where the intake opening is opened is defined as an intake port side of the combustion chamber, and a side where the exhaust opening is opened is defined as an exhaust port side of the combustion chamber, with respect to a position, as a reference, where an ignition portion of the ignition plug is disposed in a plan view from one side in a cylinder axis direction,
the piston has an intake-side flat portion at an end on the intake port side of the crown surface, and an exhaust-side flat portion at an end on the exhaust port side of the crown surface, the exhaust-side flat portion being separate and spaced apart from the intake-side flat portion,
the injector is configured to inject fuel at least toward the exhaust port side, and
a reverse squish flow generation portion, which draws an air-fuel mixture toward the intake port side as the piston moves in an expansion stroke, includes the intake-side flat portion and the combustion chamber ceiling surface,
an area of the intake-side flat portion is larger than an area of the exhaust-side flat portion, and
a maximum width of the exhaust-side flat portion is narrower than a maximum width of the intake-side flat portion in an engine output axis direction.

2. The spark ignited engine according to claim 1 , wherein
a cavity, which is recessed in the cylinder axis direction, is provided on the crown surface of the piston, and
the cavity is formed in such a way that a depth of a bottom surface of the cavity gradually decreases from the exhaust port side toward a side of the ignition portion of the ignition plug.

3. The spark ignited engine according to claim 2 , wherein
the cavity is formed into an annular shape in a state that a part of the cavity overlaps the ignition portion of the ignition plug, in a plan view from the one side in the cylinder axis direction.

4. The spark ignited engine according to claim 3 , wherein
an outer rim of the cavity includes a plug pointing portion, which is curved toward the ignition portion of the ignition plug when viewed in the cylinder axis direction.

5. The spark ignited engine according to claim 1 , wherein
the combustion chamber ceiling surface is formed into a pent-roof shape.

6. The spark ignited engine according to claim 1 ,
comprising an intake-side flat portion and an intake-side slope portion, wherein
the intake-side slope portion is located between the intake-side flat portion and the region corresponding to the ignition plug, and inclined obliquely upwardly from the intake port side toward the exhaust port side,
the ignition portion of the ignition plug includes a ground electrode of an L-shape in a side view, and
a distal end of the ground electrode faces radially inwardly of a cylinder in a plan view from the one side in the cylinder axis direction.

7. The spark ignited engine according to claim 1 , wherein
a cavity, which has a cup-shape and is recessed in the cylinder axis direction at a position on the exhaust port side with respect to the reverse squish flow generation portion in a plan view from the one side in the cylinder axis direction, is provided on the crown surface of the piston.

8. The spark ignited engine according to claim 7 , wherein
the cavity is formed of a curved surface curved in the cylinder axis direction, and
opposing side portions of a rim portion of the cavity in an engine output axis direction are each formed of a curved surface having a curvature radius smaller than a curvature radius of an inner region of the rim portion in a plan view from the one side in the cylinder axis direction.

9. The spark ignited engine according to claim 8 , wherein
the opposing side portions of the rim portion of the cavity in the engine output axis direction are located such that the ignition portion is interposed therebetween, when the piston is in a compression top dead center position.

10. The spark ignited engine according to claim 7 , wherein
a part of the cavity overlaps the ignition portion of the ignition plug in a plan view from the one side in the cylinder axis direction.

11. The spark ignited engine according to claim 7 , wherein
the combustion chamber ceiling surface is formed into a pent-roof shape.

12. The spark ignited engine according to claim 7 , wherein
comprising an intake-side flat portion and an intake-side slope portion, wherein
the intake-side slope portion is located between the intake-side flat portion and the region corresponding to the ignition plug, and inclined obliquely upwardly from the intake port side toward the exhaust port side,
the ignition portion of the ignition plug includes a ground electrode of an L-shape in a side view, and
a distal end of the ground electrode faces radially outwardly of a cylinder in a plan view from the one side in the cylinder axis direction.

13. The spark ignited engine according to claim 2 , wherein
the intake-side flat portion and the exhaust-side flat portion are arranged away from each other on opposing sides of the cavity with the cavity interposed therebetween.

14. The spark ignited engine according to claim 1 , wherein
in a plan view from the one side in the cylinder axis direction,
the cavity has a substantially C-shape, and
the ignition portion of the ignition plug is disposed at a position where the ignition portion overlaps the C-shaped opened portion of the cavity.

15. The spark ignited engine according to claim 1 , wherein
an intake-side top surface portion is provided in a region on an intake side of the combustion chamber ceiling surface, the intake-side top surface portion being opposed to the intake-side flat portion with a gap therebetween when the piston is in the compression top dead center position, and an exhaust-side top surface portion is provided in a region on an exhaust side of the combustion chamber ceiling surface, the exhaust-side top surface portion being opposed to the exhaust-side flat portion with a gap therebetween when the piston is in the compression top dead center position, and
the reverse squish flow generation portion is formed such that an area where the intake-side flat portion and the intake-side top surface are opposed to each other is larger than an area where the exhaust-side flat portion and the exhaust-side top surface are opposed to each other to draw the air-fuel mixture toward the intake port side as the piston is lowered in the expansion stroke.

Assignees

• Mazda Motor

Inventors

• Imamura Satoshi
• Fukuma Masaki
• Nakahara Yasushi
• Inoue Atsushi
• Matsumoto Kota
• Ueki Yoshiharu
• Kawano Michiharu
• Honda Yuya
• ONISHI Kento

Classifications

• Y02T10/12

  Improving ICE efficiencies · CPC title

• F02B23/101 Primary

  the injector being placed on or close to the cylinder centre axis, e.g. with mixture formation using spray guided concepts · CPC title

• F02B23/10

  with separate admission of air and fuel into cylinder · CPC title

• F02F3/26

  having combustion chamber in piston head (the surface thereof being covered F02F3/14) · CPC title

• F02B2023/108

  Swirl flow, i.e. the axis of rotation of the main charge flow motion is vertical · CPC title