Two-stroke internal combustion engine

Claim 2

A two-stroke internal combustion engine of the type wherein the gas exchange is controlled by means of inlet port means and exhaust port means in conjunction with at least one piston; said engine comprising: cylinder means having an upper and lower end, a piston arranged for reciprocating up and down movement within said cylinder means, said piston having a piston head portion with a substantially flat upper surface at the upper end Thereof, inlet port means including at least one inlet port opening arranged in said cylinder means for cooperating with said piston to introduce fresh gas to said cylinder means upon movement of said piston head portion below the upper edge of said at least one opening, wherein the upper edge of said at least one opening and the upper peripheral edges of the head portion are so constructed that fresh gas initially entering the upper part of said at least one opening is directed substantially toward the upper surface of said head portion, and gas guide means arranged immediately below the upper edge of said at least one opening for radially guiding the initially entering fresh gas, said gas guide means including at least one tongue projecting into said at least one opening approximately perpendicularly to the longitudinal axis of the cylinder means.

Claim 3

An internal combustion engine according to claim 1, wherein an annular ring means surrounds said cylinder means in a position closely spaced below said at least one opening, and wherein said at least one tongue is mounted at the upper side of said ring means such that said at least one tongue extends from said ring means upwardly to the upper edge of said at least one opening, whereby said ring means and said at least one tongue together with the upper edge of said at least one opening delimit nozzle openings for the initially entering fresh gas.

Claim 4

An internal combustion engine according to claim 2, wherein the lower edge of said at least one opening is spaced from the lowermost extent of said ring means by an amount substantially greater than the distance between said ring means and the upper edge of the at least one opening, and wherein said at least one opening is uninterrupted from the bottom of said ring means to the lower edge of said at least one opening, whereby fresh gas introduced after initial opening of said at least one opening is introduced into said cylinder means with a minimum of turbulence to reduce mixing of said fresh gas with exhaust gas remaining in the cylinder means.

Claim 5

An internal combustion engine according to claim 1, wherein a plurality of inlet port openings are provided, each of said inlet port openings having at least one tongue projecting therein.

Claim 6

An internal combustion engine according to claim 2, wherein a plurality of inlet port openings are provided, each of said inlet port openings having at least one tongue projecting therein.

Claim 7

An internal combustion engine according to claim 5, wherein said inlet port openings are asymmetrically arranged on the circumference of said cylinder means, and wherein exhaust port means are provided along the same vertical plane as said inlet openings which include at least one exhaust port opening arranged asymmetrically with respect to said inlet openings, whereby reverse scavenging takes place upon operation of the engine.

Claim 8

An internal combustion engine according to claim 3, wherein a plurality of inlet port openings are provided, each of said inlet port openings having at least one tongue projecting therein.

Claim 9

An internal combustion engine according to claim 7, wherein said inlet port openings are asymmetrically arranged on the circumference of said cylinder means, and wherein exhaust port means are provided along the same vertical plane as said inlet openings which include at least one exhaust port opening arranged asymmetrically with respect to said inlet openings, whereby reverse scavenging takes place upon operation of the engine.

Claim 10

A piston-cylinder arrangement for use on a two-stroke internal combustion engine of the type wherein the gas exchange is controlled by means of inlet port means and exhaust port means in conjunction with at least one piston, said arrangement comprising: cylinder means having an upper and lower end, a piston arranged for reciprocating up and down movement within said cylinder means, said piston having a piston head portion with a substantially flat upper surface at the upper end thereof, inlet Port means including at least one inlet port opening arranged in said cylinder means for cooperating with said piston to introduce fresh gas to said cylinder means upon movement of said piston head portion below the upper edge of said at least one opening, wherein the upper edge of said at least one opening and the upper peripheral edges of the head portion are so constructed that fresh gas initially entering the upper part of said at least one opening is directed substantially toward the upper surface of said head portion, and gas guide means arranged immediately below the upper edge of said at least one opening for radially guiding the initially entering fresh gas, said gas guide means including at least one tongue projecting into said at least one opening approximately perpendicularly to the longitudinal axis of the cylinder means.

Claim 11

A piston-cylinder arrangement for use on a two-stroke internal combustion engine of the type wherein the gas exchange is controlled by means of inlet port means and exhaust port means in conjunction with at least one piston, said arrangement comprising: cylinder means having an upper and lower end, a piston arranged for reciprocating up and down movement within said cylinder means, said piston having a piston head portion with a substantially flat upper surface at the upper end thereof, inlet Port means including at least one inlet port opening arranged in said cylinder means for cooperating with said piston to introduce fresh gas to said cylinder means upon movement of said piston head portion below the upper edge of said at least one opening, wherein the upper edge of said at least one opening and the upper peripheral edges of the head portion are so constructed that fresh gas initially entering the upper part of said at least one opening is directed substantially toward the upper surface of said head portion, and gas guide means arranged immediately below the upper edge of said at least one opening for radially guiding the initially entering fresh gas, said gas guide means including at least one tongue projecting into said at least one opening approximately perpendicularly to the longitudinal axis of the cylinder means.

Claim 12

An arrangement according to claim 9, wherein an annular ring means surrounds said cylinder means in a position closely spaced below said at least one opening, and wherein said at least one tongue is mounted at the upper side of said ring means such that said at least one tongue extends from said ring means upwardly to the upper edge of said at least one opening, whereby said ring means and said at least one tongue together with the upper edge of said at least one opening delimit nozzle openings for the initially entering fresh gas.

Claim 13

An arrangement according to claim 10, wherein a plurality of inlet port openings are provided, each of said inlet port openings having at least one tongue projecting therein.

Claim 14

An arrangement according to claim 11, wherein said inlet port openings are asymmetrically arranged on the circumference of said cylinder means, and wherein exhaust port means are provided along the same vertical plane as said inlet openings which include at least one exhaust port opening arranged asymmetrically with respect to said inlet openings, whereby reverse scavenging takes place upon operation of the engine.

Claim 15

A two-stroke internal combustion engine according to claim 4, characterized in that the cylinder means includes a cylinder liner.

Claim 16

A two-stroke internal combustion engine according to claim 1, characterized in that the engine includes two substantially flat pistons.

Claim 17

A two-stroke internal combustion engine according to claim 1, characterized in that at least that part of the flank portion adjoining an opening upper control edge of the at least one opening forms an acute angle with an adjoining working surface of the cylinder.

Claim 18

A two-stroke internal combustion engine according to claim 15, characterized in that the last-mentioned flank portion is in the form of a hollow trough.

Claim 19

A two-stroke internal combustion engine according to claim 2, characterized in that the inlet port openings are so shaped that they open and close with their maximum width in the direction of the periphery of the cylinder.

Claim 20

A two-stroke internal combustion engine according to claim 17, characterized in that the exhaust port means are also so shaped that they open and close with their maximum width in the direction of the periphery of the cylinder.

Claim 21

An internal combustion engine according to claim 17, characterized in that the inlet port openings exhibit a partial disc-shaped slightly concave profile cross-section when viewed from a direction perpendicular to both the cylinder axis and respective radially extending centerlines, and in that said openings are larger on the outside of the cylinder means than on the inside.

Claim 22

A two-stroke internal combustion engine according to claim 17, characterized in that the inlet port openings are disposed in a ring around a cylinder liner in such a manner that the total width of their intermediate lands at the commencement of the opening amount to only a small fraction of the periphery of the cylinder means.

Claim 23

An internal combustion engine according to claim 17, characterized in that in order to enable the initial fresh gas to impinge more effectively aGainst the upper surface of the piston head portion, the piston head portion is bevelled off at its peripheral edges.

Claim 24

A two-cycle internal combustion engine according to claim 17, characterized in that in order to enable the initial fresh gas to impinge more effectively against the upper surface of the piston head portion, the piston head portion is slightly curved outwardly.

Claim 25

An internal combustion engine according to claim 20, characterized in that at the height of the inner top edge of the inlet port openings, the cylinder means is divided into two parts by an annular gap extending substantially perpendicular to the axis of the cylinder means.

Claim 26

An internal combustion engine according to claim 23, characterized in that the annular gap is delimited on the lower cylinder part by at least one flat annular member which rests on lands between the inlet port openings.

Claim 27

A two-cycle internal combustion engine according to claim 14, characterized in that guide and spacer rib means forming part of said gas guide means are arranged at the annular member.

Claim 28

A two-cycle internal combustion engine according to claim 25, characterized in that several such annular members provided with guide rib means are arranged one above the other between the cylinder parts.

Claim 29

An internal combustion engine according to claim 23, characterized in that one of the cylinder parts is a working cylinder part and in that the working cylinder part is provided at its end faces with a profile ending in an acute angle for the admission and exhaust.

Claim 30

A two-cycle internal combustion engine according to claim 6, characterized in that the at least one exhaust port opening has an at least approximately triangular cross-section which is opened first by the piston at the larger width thereof.

Claim 31

A two-cycle internal combustion engine according to claim 6, characterized in that the at least one exhaust port opening has an at least approximately trapezoidally shaped cross-section which is opened first by the piston at the larger width thereof.

Claim 32

An internal combustion engine according to claim 1, characterized in that at the height of a controlling upper edge of the exhaust port means, the cylinder is divided axially by gaps perpendicular to the axis of the cylinder, the gap in the axial direction being smaller than the height of a piston ring.

Claim 33

An internal combustion engine according to claim 30, characterized in that the last of the parts of a divided cylinder, which are provided with profiled inlet or exhaust port means, is made of a metal which has better thermal conductivity than the expansion part of a working cylinder means.

Claim 34

A two-cycle internal combustion engine according to claim 31, characterized in that said last part is made of a metal which is lighter in weight and has a better thermal conductivity than cast-iron.

Claim 35

A two-cycle internal combustion engine according to claim 1, characterized in that edges delimiting the inlet and exhaust port means are rounded off.

Claim 36

An internal combustion engine according to claim 1, characterized in that particularly in the case of an axially divided cylinder, the part of a cylinder which is provided with the port means, and which is correspondingly profiled on its end face is manufactured by a shell molding process.

Claim 37

A two-stroke internal combustion engine according to claim 17, characterized in that the exhaust port means are also so shaped that they open and close with their maximum width in the direction of the periphery of the cylinder means.

Claim 38

A two-stroke internal combustion engine according to claim 13, characterized in that the inlet port openings are disposed in a ring around the cylinder liner in such a manner that the total width of their intermediate lands at the commencement of the opening amounts to only a small fraction of the periphery of the cylinder means.

Claim 39

An internal combustion engine according to claim 1, characterized in that in order to enable the initial fResh gas to impinge more effectively against the upper surface of the piston head portion, the piston head portion is bevelled off at its peripheral edges.

Claim 40

An internal combustion engine according to claim 1, characterized in that at the height of the inner top edge of the inlet port means, the cylinder is divided into two parts by an annular gap substantially perpendicular to the axis of the cylinder, one of said cylinder parts being a working cylinder part.

Claim 41

An internal combustion engine according to claim 38, characterized in that the annular gap is delimited on the lower cylinder part by at least one flat annular member which rests on the lands between the inlet port openings.

Claim 42

A two-cycle internal combustion engine according to claim 39, characterized in that guide and spacer rib means forming part of the gas guide means are arranged at the annular member.

Claim 43

A two-cycle internal combustion engine according to claim 39, characterized in that several such annular members provided with guide rib means are arranged one above the other between the cylinder parts.

Claim 44

An internal combustion engine according to claim 38, characterized in that the working cylinder part is provided at the end faces for the admission and exhaust, with a profile ending in an acute angle.