Combustion chamber of spark ignition internal combustion engine

Claim 2

In an engine cylinder assembly for a spark ignition internal combustion engine having (a) a cylinder, (b) a piston reciprocatingly slidable in said cylinder and having a flat top surface, (c) a cylinder head sealing an end of said cylinder to define a cylindrical variable volume chamber between a flat surface thereof and said flat piston top surface, (d) a first domeshaped recess to serve as a main combustion chamber having an opening area smaller than 50% of the area of said piston top surface, the location thereof being off center with respect to the longitudinal axis of said cylinder, and (e) a spark plug, said cylindrical chamber being reduced in volume so as to establish a squish causing area when said piston nears the top dead center (f) a second dome-shaped recess smaller in volume than said first recess to serve as an ignition chamber, the location thereof being separate from said first recess, off center with respect to said axis and faced to the spark gap of said spark plug when said piston nears the top dead center, (g) means to supply a combustible airfuel mixture to the cylinder chamber, the improvement comprising the provision of (h) means defining a concavity shallower than said first recess and arranged substantially around the opening of said first recess, the cross-section thereof being varied to be largest at the opening thereof exposed to said cylindrical chamber and smallest at the bottom thereof so that the influence of squish on said first recess is lessened, and (i) said second domeshaped recess having a sharp-edged mouth periphery.

Claim 3

The improvement as claimed in claim 1, wherein the volume ratio of said second recess to said first recess is between about one one-hundredth and about one-fourth.

Claim 4

The improvement as claimed in claim 1, wherein said assembly is provided with said concavity at a region adjacent to and surrounding the opening of said first recess on a flat surface.

Claim 5

The improvement as claimed in claim 1, wherein said assembly is provided with said concavity at a region on a flat surface opposite to the opening of said first recess.

Claim 6

An engine cylinder assembly of a spark ignition internal combustion reciprocating engine eomprising (a) a cylinder, (b) a piston in said cylinder having a flat top surface, (c) a cylinder head sealing an end of said cylinder to define a cylindrical variable volume chamber between a flat surface thereof and said flat piston top surface, (d) a first dome-shaped recess to serve as a main combustion chamber, (e) a second dome-shaped recess to serve as an ignition chamber, smaller in volume than said first recess and separate from said first recess, (f) a spark plug installed on said cylinder head, the spark gap thereof being exposed to said second recess when said piston nears the top dead center, (g) means to supply a combustible air-fuel mixture to the cylinder chamber, and (h) means defining a concavity shallower than said first recess and arranged substantially around the opening of said first recess; said cylindrical chamber being reduced in volume enough to establish a squish causing area when said piston nears the top dead center, locations of said two recesses being off center with respect to the longitudinal axis of said cylinder, each of the openings of said two recesses being exposed to said cylindrical chamber and occupying an area less than 50% of the area of said piston top surface, the bottoms thereof being curved, and the cross-section of said concavity being varied to be largest at the opening thereof exposed to said cylindrical chamber and smallest at the bottom thereof so that the establishment of said squish causing area is disturbed at a region facing said concavity.

Claim 7

An engine cylinder assembly of a spark ignition internal combustion reciprocating engine eomprising (a) a cylinder, (b) a piston in said cylinder having a flat top surface, (c) a cylinder head sealing an end of said cylinder to define a cylindrical variable volume chamber between a flat surface thereof and said flat piston top surface, (d) a first dome-shaped recess to serve as a main combustion chamber, (e) a second dome-shaped recess to serve as an ignition chamber, smaller in volume than said first recess and separate from said first recess, (f) a spark plug installed on said cylinder head, the spark gap thereof being exposed to said second recess when said piston nears the top dead center, (g) means to supply a combustible air-fuel mixture to the cylinder chamber, and (h) means defining a concavity shallower than said first recess and arranged substantially around the opening of said first recess; said cylindrical chamber being reduced in volume enough to establish a squish causing area when said piston nears the top dead center, locations of said two recesses being off center with respect to the longitudinal axis of said cylinder, each of the openings of said two recesses being exposed to said cylindrical chamber and occupying an area less than 50% of the area of said piston top surface, the bottoms thereof being curved, and the cross-section of said concavity being varied to be largest at the opening thereof exposed to said cylindrical chamber and smallest at the bottom thereof so that the establishment of said squish causing area is disturbed at a region facing said concavity.

Claim 8

An engine cylinder assembly as claimed in claim 5, wherein the volume ratio of said second recess to said first recess is about one one-hundredth to about one-fourth.

Claim 9

An engine cylinder assembly as claimed in claim 5, wherein said cylinder head is provided with said first recess and said second recess.

Claim 10

An engine cylinder assembly as claimed in claim 5, wherein said piston is provided with said first recess and said second recess.

Claim 11

An engine cylinder assembly as claimed in claim 8, wherein said piston top surface is provided with said concavity at a region adjacent to and surrounding said opening of said first recess.

Claim 12

An engine cylinder assembly as claimed in claim 8, wherein said flat surface of said cylinder head is provided with said concavity at a region opposite to and substantially around said opening of said first recess.

Claim 13

An engine cylinder assembly as claimed in claim 8, wherein said piston top surface is further provided with a groove connecting said first and second recesses to facilitate flame front propagation from said second recess to said first recess.

Claim 14

An engine cylinder assembly as claimed in claim 11, wherein said flat surface of said cylinder head is provided with said concavity at a region adjacent to and surrounding said opening of said first recess.

Claim 15

An engine cylinder assembly as claimed in claim 11, wherein said piston top surface is provided with said concavity at a region opposite to and substantially around said opening of said first recess.

Claim 16

An engine cylinder assembly as claimed in claim 11, wherein said flat surface of said cylinder head is further provided with a groove connecting said first and second recesses to facilitate flame front propagation from said second recess to said first recess.

Claim 17

An engine cylinder assembly as claimed in claim 11, wherein said piston is provided with a third dome-shaped recess and a fourth recess smaller in volume than said third recess, the openings thereof being located opposite to said openings of said first recess and said second recess, respectively, and the total volume of said second and fourth recesses is between about one one-hundredth to about one-fourth of the total volume of said first and third recesses.

Claim 18

An engine cylinder assembly as claimed in claim 15, wherein said piston top surface is further provided with a groove connecting said third and fourth recess.

Claim 19

An engine cylinder assembly as claimed in claim 5, wherein said cylinder head is provided with said second recess and said piston is provided with said first recess.

Claim 20

An engine cylinder assembly as claimed in claim 5, wherein said openings of said first and second recesses are generally circular.

Claim 21

An engine cylinder assembly as claimed in claim 18, wherein the width of said concavity is about one-fiftieth to one-fifth of the diameter of said first recess.

Claim 22

An engine cylinder assembly as claimed in claim 5, wherein said opening of said first recess is generally oval.