Combustion chamber structure for internal combustion engine

Patent metadata

Field	Value
Publication number	US-10024267-B2
Application number	US-201114365170-A
Country	US
Kind code	B2
Filing date	Dec 16, 2011
Priority date	Dec 16, 2011
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

A combustion chamber structure for an internal combustion engine includes, in a piston top part, a concave portion formed eccentrically with respect to a cylinder center axis, and a tapered portion that connects an upper end face of the piston top part and a side face of the concave portion. The tapered portion is formed so that a tapered portion volume (volume of a space formed between the tapered portion and an upper wall surface of the combustion chamber) in a first portion of the piston top part is greater than a tapered portion volume in a second portion that is nearer than the first portion to an eccentric direction of the concave portion from the cylinder center axis.

First claim

The invention claimed is:

1. A combustion chamber structure for an internal combustion engine, comprising:
a concave portion that is formed in a piston top part in an eccentric manner relative to a cylinder center; and
a tapered portion that is arranged so as to surround a circumference of the concave portion and also connects an upper end face of the piston top part and a side face of the concave portion,
wherein a squish area width is a horizontal distance between an outer edge portion of the upper end face of the piston top part and an inner edge portion of the tapered portion,
wherein in a case where two regions of the same squish area widths are compared, a center of an outer edge portion of the tapered portion is made eccentric with respect to the cylinder center so that a width in a horizontal direction of the tapered portion on a side of a region in which a swirl flow velocity becomes slow is smaller than a width in the horizontal direction of the tapered portion on a side of a region in which the swirl flow velocity becomes fast,
wherein from a planar view of the piston top part, an eccentric direction of the outer edge portion of the tapered portion relative to the cylinder center is a direction perpendicular to a line segment connecting the cylinder center and a center of the concave portion, and
wherein from the planar view of the piston top part, a width of the tapered portion in an eccentric side on an extended line passing through the center of the outer edge portion of the tapered portion and the cylinder center is larger than a width of the tapered portion on an extended line of the line segment.

2. The combustion chamber structure for an internal combustion engine according to claim 1 , wherein the combustion chamber structure in which two intake valves have mutually different diameters comprises:
two valve recesses having different diameters that are formed in the piston top part in correspondence with the two intake valves, respectively, wherein
among the two valve recesses, a valve recess that has a larger diameter is arranged in a region in which a swirl flow velocity is faster in comparison to a valve recess that has a smaller diameter.

3. A combustion chamber structure for an internal combustion engine that is a combustion chamber structure in which two intake valves having mutually different diameters are arranged, comprising:
two valve recesses having different diameters that are formed in the piston top part in correspondence with the two intake valves, respectively, wherein the two valve recesses are separate from each other;
a concave portion that is formed in the piston top part in an eccentric manner relative to a cylinder center; and
a tapered portion that is arranged so as to surround a circumference of the concave portion and also connects an upper end face of the piston top part and a side face of the concave portion, wherein
a tapered portion volume that is a volume of a space formed between the tapered portion and a combustion chamber upper wall surface in a first portion of the piston top part is greater than a tapered portion volume in a second portion that is nearer than the first portion to an eccentric direction of the concave portion from a center of the cylinder,
among the two valve recesses, a valve recess that has a larger diameter is arranged in a region in which a swirl flow velocity is faster in comparison to a valve recess that has a smaller diameter, and
from a planar view of the piston top part, an eccentric direction of the outer edge portion of the tapered portion relative to the cylinder center is a direction perpendicular to a line segment connecting the cylinder center and a center of the concave portion, and
wherein from the planar view of the piston top part, a width of the tapered portion in an eccentric side on an extended line passing through the center of the outer edge portion of the tapered portion and the cylinder center is larger than a width of the tapered portion on an extended line of the line segment.

Assignees

• Nishida Kentaro
• Oyagi Hiroshi
• Toyota Motor Co Ltd

Inventors

• Nishida Kentaro
• Oyagi Hiroshi

Classifications

• F02B23/0696

  W-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 wall · CPC title

• F02F1/00 Primary

  Cylinders; Cylinder heads · CPC title

• F02B23/0624

  Swirl flow · CPC title

• F02B23/069 Primary

  characterised by its eccentricity from the cylinder axis · CPC title

• F02B23/0621

  Squish flow · CPC title