Air intake porting for a two stroke engine
View Patent ↗A two stroke engine of a particular configuration can have its power output increased by running bigger pistons and using ports in the piston skirt through which to conduct compressed air within the skirt through short passages in the cylinder housing that conduct the air from within the skirt to above the piston. As a result a larger piston can be used for the same spacing and opening size in the block to save the need to redesign the block and the crankshaft. A position adjuster for the piston moves it axially without rotation of the piston ports out of alignment with inlet ports in the housing. The piston rod is held in the crosshead using a flat to prevent rotation while an adjuster nut that is turned creates axial movement in the piston rod with a lock nut securing the final piston position.
1. A two stroke engine, comprising:
at least one cylinder housing having a reciprocating piston therein, wherein the piston comprises a skirt having a plurality of ports spaced circumferentially for at least 180 degrees on the skirt, and wherein the piston defines a lower zone in the cylinder housing where fluid is compressed when the piston strokes downwardly and a compression zone in the cylinder housing where fluid is compressed by upward piston movement, whereupon the piston attaining a predetermined position, fluid flows once through the skirt and into the compression zone.
2. The engine of claim 1 , wherein the skirt ports are aligned along a common circumference of the skirt.
3. The engine of claim 1 , wherein the cylinder housing comprises at least one passage having an inlet and a spaced outlet, whereupon alignment of the skirt port and the inlet, fluid can flow through the passage to the compression zone.
4. The engine of claim 3 , wherein:
the number of said skirt ports is equal to the number of passages in said cylinder housing.
5. The engine of claim 3 , wherein:
said passage is substantially aligned with a longitudinal axis.
6. The engine of claim 3 , wherein:
said cylinder housing comprises at least one exhaust port that is circumferentially spaced from said outlet.
7. The engine of claim 6 , wherein:
said at least one passage comprises a plurality of passages and said at least one exhaust port comprises a plurality of exhaust ports said exhaust ports being circumferentially offset from said outlets.
8. The engine of claim 7 , wherein:
said exhaust ports are aligned with said outlets on a common circumference.
9. A two stroke engine, comprising:
at least one cylinder housing having a reciprocating piston therein;
said piston defining a lower zone in said housing where fluid is compressed when said piston strokes downwardly and a compression zone in said housing where fluid is compressed by upward piston movement, whereupon said piston attaining a predetermined position fluid flows through said piston and into said compression zone;
said piston further comprises a rod connected to a crosshead, said crosshead further comprising an adjuster to alter the position of the piston axially without rotating said rod.
10. The engine of claim 9 , wherein:
said rod is constrained against rotation where it extends into said crosshead.
11. The engine of claim 10 , wherein:
said rod comprises a flat that aligns with a matching flat in an opening in said crosshead, said rod further comprising threads on opposed sides of said flat that extend inside and outside of said crosshead, said adjuster mounted to threads within said crosshead and a lock nut is mounted on said thread outside said crosshead.
12. A two stroke engine, comprising:
at least one cylinder housing having a reciprocating piston therein;
said piston defining a lower zone in said housing where fluid is compressed when said piston strokes downwardly and a compression zone in said housing where fluid is compressed by upward piston movement, whereupon said piston attaining a predetermined position fluid flows through said piston and into said compression zone;
said piston comprises a skirt and said flow of fluid flows through said skirt;
said skirt comprises at least one skirt port;
said cylinder housing comprises at least one passage having an inlet and a spaced outlet, whereupon alignment of said skirt port and said inlet fluid can flow through said passage to said compression zone;
said piston can have its position axially adjusted within said cylinder housing without rotating said skirt port out of circumferential alignment with said inlet to said passage.
13. A method of increasing the power output from a two stroke engine while retaining the same block, comprising:
removing any cylinder housing having a first bore and an associated piston that leaves room for fluid passage around the outside of a piston skirt where the piston reciprocates through the bore of the cylinder housing, which is connected to an opening in the block; and
replacing said associated piston with a bigger piston and skirt in a bigger second bore in a replacement cylinder housing without enlarging the opening in said block.
14. The method of claim 13 , comprising:
providing at least one port in a skirt of said piston for fluid passage.
15. The method of claim 13 , comprising:
eliminating the fluid passage outside the piston skirt with said bigger piston.
16. The method of claim 13 , comprising:
providing an axial adjustment mechanism to adjust the piston to head clearance of said bigger piston without rotation of said bigger piston.
17. A two-stroke engine, comprising:
a piston having a top portion and a skirt extending from the top portion, and including a plurality of piston ports extending radially through the skirt; and
a cylinder housing having an inner peripheral surface that defines a chamber configured to receive the piston, and first and second chamber ports in fluid communication with the chamber and with each other.
18. The engine of claim 17 , wherein the piston is configured to move axially within the cylinder housing without significant rotation.
19. The engine of claim 17 , wherein:
the piston defines a lower zone in the chamber where fluid is compressed when the piston strokes downward and a compression zone in the chamber where fluid is compressed when the piston strokes upward; and
the first and second chamber ports and the piston ports are configured to allow fluid communication between the lower zone and the compression zone when the piston ports are aligned with the first chamber ports.
20. The engine of claim 17 , wherein the plurality of piston ports are spaced circumferentially along a common circumference of the skirt.
21. The engine of claim 17 , wherein the cylinder housing comprises at least one exhaust port spaced circumferentially from the first and second chamber ports.
22. A two-stroke engine, comprising:
a cylinder housing defining a combustion chamber and including a channel extending therethrough, the channel having an inlet and an outlet separated from one another by a portion of the cylinder housing, wherein the channel outlet is in fluid communication with the combustion chamber; and
a piston disposed in the cylinder housing, configured to reciprocate therein, and comprising a top surface and a skirt portion extending from the top surface, the skirt portion comprising at least one aperture extending therethrough;
wherein the piston and channel are configured such that when the at least one aperture is at least partially aligned with the inlet, the outlet is at least partially located above the top surface of the piston.