US RE32,802 E · Two-cycle engine with improved scavenging

Abstract

A two-cycle internal combustion engine having an "open" combustion chamber/poppet valve arrangement that produces improved scavenging. The combustion chamber has a generally oblate configuration and is slanted with respect to the cylinder axis in such a manner that the air flowing therein converges and is directed downward in a collimated column into the cylinder. The placement of overhead cam operated poppet valves in combination with the combustion chamber produces a scavenging method of the reverse return-flow type. A displacer piston having a displacer with a peripheral wall corresponding in configuration to that of the combustion chamber and defining a recess of predetermined volume that forms the floor of the combustion chamber when the piston is located in its upper most position may be advantageously employed. Variable valve timing is achieved by opening and closing the exhaust and inlet valves unsymmetrically in order to improve the scavenging efficiency and asymmetrically to cause an increase in the effective expansion ratio.

Claims78

Dependent claims

An improved two-cycle internal combustion engine comprising:

a cylinder;
a cylinder head having an exhaust valve and an open type combustion chamber located therein, said chamber and exhaust valve being located in side-by-side relationship on opposite sides of a central axis of the cylinder;
an air inlet valve located within and in the top of the combustion chamber, said inlet valve having a valve stem located overhead said cylinder;
a piston reciprocally disposed within the cylinder;
means for converging a flow of scavenging air beneath the inlet valve into a colimated column as it enters the cylinder, said converging means comprising the combustion chamber having a generally oblate configuration with sides converging downwardly to form an opening which overlies the cylinder, the combustion chamber having diametrically opposed sides with predetermined different angles of curvature;
and
wherein the inlet valve and the combustion chamber are coaxially aligned and oriented to the central axis of the cylinder at a predetermined angle and wherein the flow of scavenging air is directed toward and along an inside wall of the cylinder, said inside wall being on the same side of the cylinder axis as the combustion chamber.

4 more elements

A two-cycle internal combustion engine, comprising

(a) an engine block containing at least one cylinder cavity defined in part by a cylindrical sidewall;
(b) a piston mounted for reciprocal movement within said cylinder cavity;
(c) an engine head positioned across one end of said cylinder cavity to define a cylinder cavity end wall, said head containing an open combustion chamber communicating directly with said cylinder cavity through a combustion chamber outlet opening contained in said cylinder cavity end wall, said combustion chamber outlet opening being radially offset with respect to the central axis of said cylinder cavity and immediately adjacent one portion of the perimeter of said end wall;
(d) at least one inlet valve and one exhaust valve mounted within said head, said inlet valve being positioned within said combustion chamber;
and
(e) valve actuating means for operating said inlet and exhaust valves in timed sequence with said piston motion to produce two cycle engine operation including a scavenging period during which said valves are both open to produce a reverse-return-flow of scavenging air through said cylinder cavity;
wherein the location of said inlet valve within said combustion chamber is selected and said combustion chamber is shaped in parts with predetermined differing radii of curvature such that air admitted into said combustion chamber by said inlet valve is collected and directed into a converged, single column, collimated air stream passing through said combustion chamber outlet opening into said cylinder cavity axially along and closely adjacent the axial portion of said cylindrical sidewall which extends axially away from said one portion of the perimeter of said end wall, and wherein said opening is shaped and is sufficiently large in size to cause said collimated air stream to proceed axially along said axial portion of said cylindrical sidewall and to have a sufficient flow area and flow velocity to remain unbroken and substantially collimated until it reaches said piston and to cause said scavenging air stream to sweep the internal solid surfaces of said cylinder cavity.

4 more elements

A two-cycle internal combustion engine, comprising

(a) an engine block containing at least one cylinder cavity defined in part by a cylindrical sidewall;
(b) a piston mounted for reciprocal movement with in said cylinder cavity;
(c) an engine head positioned across one end of said cylinder cavity to define a cylinder cavity end wall, said head containing a non-spherical open combustion chamber communicating directly with said cylinder cavity through a combustion chamber outlet opening contained in said cylinder cavity end wall, said combustion chamber outlet opening being radially offset with respect to the central axis of said cylinder cavity and immediately adjacent one portion of the perimeter of said end wall;
(d) at least one inlet valve and one exhaust valve mounted within said head, said inlet valve being positioned within said combustion chamber;
and
(e) valve actuating means for operating said inlet and exhaust valves in timed sequence with said piston motion to produce two cycle engine operation including a scavenging period during which said valves are both open to produce a reverse return flow of scavenging air through said cylinder cavity;
wherein the location of said inlet valve within said combustion chamber is selected and said combustion chamber is shaped such that air admitted into said combustion chamber by said inlet valve is collected and directed into a collimated air stream passing through said combustion chamber outlet opening into said cylinder cavity axially along and closely adjacent the axial portion of said cylindrical sidewall which extends axially away from said one portion of the perimeter of said end wall,
wherein said opening is shaped and is sufficiently large in size to cause said collimated air stream to proceed axially along said axial portion of said cylindrical sidewall and to have a sufficient flow area and flow velocity to remain unbroken and substantially collimated until it reaches said piston and to cause said scavenging air stream to sweep the internal solid surfaces of said cylinder cavity;
and
wherein said inlet valve is a poppet valve having a valve head located in said combustion chamber and having a valve stem extending from said combustion chamber in a non-parallel direction with respect to the central axis of said cylinder cavity, said combustion chamber walls contain a valve seat against which said poppet valve head is moved when said poppet valve is closed, at least one perimeter edge of said valve seat being positioned in substantial axial alignment with said one portion of the perimeter of said end wall.

7 more elements

A two-cycle internal combustion engine, comprising

(a) an engine block containing at least one cylinder cavity defined in part by a cylindrical sidewall;
(b) a piston mounted for reciprocal movement within said cylinder cavity;
(c) an engine head positioned across one end of said cylinder cavity to define a cylinder cavity end wall, said head containing an open combustion chamber communicating directly with said cylinder cavity through a combustion chamber outlet opening contained in said cylinder cavity end wall, said combustion chamber outlet opening being radially offset with respect to the central axis of said cylinder cavity and immediately adjacent one portion of the perimeter of said end wall;
(d) at least one inlet valve and one exhaust valve mounted within said head, said inlet valve being positioned within said combustion chamber;
and
(e) valve actuating means for operating said inlet and exhaust valves in timed sequence with said piston motion to produce two cycle engine operation including a scavenging period during which said valves are both open to produce a reverse-return-flow of scavenging air through said cylinder cavity;
wherein the location of said inlet valve within said combustion chamber is selected and said combustion chamber is shaped such that air admitted into said combustion chamber by said inlet valve is collected and directed into a collimated air stream passing through said combustion chamber outlet opening into said cyinder cavity axially along and closely adjacent the axial portion of said cylindrical sidewall which extends axially away from said one portion of the perimeter of said end wall,
wherein said opening is shaped and is sufficiently large in size to cause said collimated air stream to proceed axially along said axial portion of said cylindrical sidewall and to have a sufficient flow area and flow velocity to remain unbroken and substantially collimated until it reaches said piston and to cause said scavenging air stream to sweep substantially all of the internal solid surfaces of said cylinder cavity;
and
wherein said valve actuating means includes variable timing means for varying the timing of opening and closing of at least one of said inlet and exhaust valves relative to the reciprocal motion of said piston.

7 more elements

Dependencies are inferred from the claim text.

Two-cycle engine with improved scavenging

Life of this patent

Two-cycle engine with improved scavenging

Life of this patent

Abstract

Claims78