GB2475641A

GB2475641A - Air intake porting for a two stroke engine

Info

Publication number: GB2475641A
Application number: GB1103280A
Authority: GB
Inventors: Bruce A Chrisman; Randy Coleman
Original assignee: Cameron International Corp
Current assignee: Cameron International Corp
Priority date: 2006-03-03
Filing date: 2007-03-01
Publication date: 2011-05-25
Anticipated expiration: 2027-03-01
Also published as: GB2475641A8; GB2475642A; GB201103282D0; GB2475642B; GB201103280D0; GB2475641B

Abstract

A two stroke engine of a particular configuration can have its power output increased by running bigger pistons 42 and using ports 48 in the piston skirt 52 through which to conduct compressed air within the skirt through short passages 46 in the cylinder housing 58 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.

Description

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Claims

CLAI MS1. 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 an air 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.
2. The method of claim 1, comprising: providing at least one port in a skirt of said piston for an air passage.
3. The method of either of claims 1 or 2, comprising: eliminating the air passage outside the piston skirt with said bigger piston.
4. The method of any preceding claim, comprising: providing an axial adjustment mechanism to adjust the piston to head clearance of said bigger piston without rotation of said bigger piston.
5. 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 air is compressed when said piston strokes downwardly and a compression zone in said housing where air and fuel are mixed and compressed by upward piston movement, whereupon said piston attaining a predetermined position compressed air flows through said piston and into said compression zone.
6. The engine of claim 5, wherein: said piston comprises a skirt and said flow of compressed air flows through said skirt.
7. The engine of claim 6, wherein: said skirt comprises at least one skirt port.
8. The engine of claim 7, wherein: said at least one skirt port comprises a plurality of ports that are circumferentially spaced.
9. The engine of claim 8, wherein: said skirt ports extend circumferentially for at least 180 degrees on said skirt.
10. The engine of either of claims 8 or 9, wherein: said skirt ports are aligned along a common circumference of said skirt.
11. The engine of any of claims 7 to 10, wherein: said cylinder housing comprises at least one passage having an inlet and a spaced outlet, whereupon alignment of said skirt port and said inlet compressed air can flow through said passage to said compression zone.
12. The engine of claim 11, wherein: The number of said skirt ports is equal to the number of passages in said cylinder housing.
13. The engine of either of claims 11 or 12, wherein: said passage is substantially aligned with a longitudinal axis.
14. The engine of any of claims 11 to 13, wherein: said cylinder housing comprises at least one exhaust port that is circumferentially spaced from said outlet.
15. The engine of claim 14, wherein: said at least one passage comprises a plurality of passages and said at least one exhaust post comprises a plurality of exhaust ports said exhaust ports being circumferentially offset from said outlets.
16. The engine of claim 15, wherein: said exhaust ports are aligned with said outlets on a common circumference.
17. The engine of any of claims 11 to 16, wherein: 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.
18. The engine of any of claims 5 to 17, wherein: 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.
19. The engine of claim 18, wherein: said rod is constrained against rotation where it extends into said crosshead.
20. The engine of claim 19, 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 extends 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.
21. 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, first and second chamber ports in fluid communication with the chamber and with each other.
22. A two-stroke engine substantially as hereinbefore defined having reference to any of Figures 3 to 7.
23. A method of increasing the power output from a two-stroke engine substantially as hereinbefore described having reference to any of Figures 3 to 7.