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 system, comprising:
a piston comprising:
a head; and
a skirt extending from the head, wherein the skirt comprises a port;
a rod coupled to the piston; and
a feature configured to maintain an angular orientation of the port relative to a cylinder, wherein the rod does not rotate relative to the piston.
2. The system of claim 1 , comprising a plurality of the ports spaced along a common circumference of the skirt.
3. The system of claim 1 , comprising a cylinder configured to receive the piston.
4. The system of claim 3 , wherein the cylinder comprises a passage having a separate inlet and outlet in an interior surface of the cylinder, and the port in the skirt is configured to align with the inlet in the interior surface of the cylinder to enable fluid flow around the head through the passage to the outlet.
5. The system of claim 4 , comprising a plurality of the ports and a plurality of the passages, wherein the plurality of passages is equal to the plurality of ports.
6. The system of claim 1 , wherein the feature comprises a first flat surface on a side of the rod.
7. The system of claim 6 , comprising a crosshead configured to connect the piston to a crankshaft, wherein the crosshead comprises an opening configured to receive the rod, and the opening comprises a second flat surface corresponding to the first flat surface of the rod.
8. A system, comprising:
a piston comprising:
a head;
a skirt; and
a first plurality of passages through the skin, wherein the first plurality of passages is configured to enable flow through the skirt and around the head via a second plurality of passages into and separately out of a cylinder, wherein the first and second plurality of passages are disposed about at least half of a circumference of the piston.
9. The system of claim 8 , comprising the cylinder.
10. A system, comprising:
a cylinder configured to receive a piston, the cylinder comprising:
a wall;
a cylindrical bore defining an interior surface of the cylinder, wherein the interior surface defines a piston path;
a passage in the wall, wherein the passage has an inlet and a separate outlet on the interior surface of the cylinder; and
an air intake into the cylindrical bore, wherein the air intake is separate from the piston path.
11. The system of claim 10 , wherein the passage is substantially aligned with a longitudinal axis of the cylinder.
12. The system of claim 10 , comprising a plurality of passages each having the inlet and the outlet.
13. The system of claim 12 , wherein the plurality of inlets are arranged along a generally common circumference of the interior surface.
14. The system of claim 12 , wherein the plurality of outlets are arranged along a generally common circumference of the interior surface.
15. The system of claim 10 , comprising an exhaust port extending from the interior surface through the wall to an exterior of the cylinder.
16. The system of claim 15 , wherein the outlet and the exhaust port are arranged along a generally common circumference of the interior surface.
17. The system of claim 15 , wherein the exhaust port is displaced circumferentially from the passage.
18. The system of claim 10 , comprising a piston configured to operate within the cylinder, wherein a skirt of the piston comprises a port.
19. The system of claim 18 , wherein alignment of the port in the skirt with the inlet in the wall is configured to enable fluid flow through the passage into a compression zone defined by the piston and the cylinder.
20. The system of claim 18 , comprising a feature configured to prevent rotational movement of the piston with respect to the cylinder.
21. A method, comprising:
translating a rod to actuate a piston disposed in a cylinder, wherein the piston defines a combustion zone and a lower zone in the cylinder; and
displacing a first volume of fluid from the lower zone to the combustion zone through a port in a skirt of the piston and a passage in a wall of the cylinder, wherein the passage is configured such that an outlet of the passage is disposed in the combustion zone when the port in the skirt is aligned with an inlet of the passage.
22. The method of claim 21 , comprising:
actuating the piston toward the combustion zone such that the first volume of fluid in the combustion zone is compressed and a second volume of fluid is drawn into the lower zone;
igniting the first volume of fluid in the combustion zone; and
actuating the piston toward the lower zone such that exhaust from the first volume of fluid is expelled from the combustion zone through an exhaust port.
23. The method of claim 21 , wherein actuating the piston comprises displacing the piston in an axial direction and not in a rotational direction.
24. A method, comprising:
providing a piston having a head, a skirt, and a rod, and an axial adjuster, wherein the skirt comprises a port, and the axial adjuster is configured to adjust an axial position of the head and the skirt relative to the rod without rotation between the rod and the head and skirt; and
providing a cylinder configured to receive the piston, wherein the cylinder comprises a channel on an interior surface of the cylinder to communicate with the port.
25. The method of claim 24 , comprising providing an exhaust passage from the interior surface of the cylinder to an exterior of the cylinder.