Asymmetrically-shaped combustion chamber for opposed-piston engines

Patent metadata

Field	Value
Publication number	US-9995213-B2
Application number	US-201514675407-A
Country	US
Kind code	B2
Filing date	Mar 31, 2015
Priority date	Mar 31, 2015
Publication date	Jun 12, 2018
Grant date	Jun 12, 2018

Abstract

A combustion chamber for an opposed-piston engine has an elongated asymmetrical shape in longitudinal section that runs along a chamber centerline, between diametrically-opposed openings of the combustion chamber through which fuel is injected. The asymmetry apportions combustion chamber volume to provide additional clearance on a side of the chamber centerline toward which swirl is directed, thereby giving a fuel plume space to swing without hindrance in response to swirl.

First claim

The invention claimed is:

1. An opposed-piston engine including at least one cylinder with a bore, piston-controlled exhaust and intake ports near respective ends of the cylinder, and a pair of pistons disposed in opposition in the bore, in which:
each piston has a crown with an end surface defining a combustion chamber in the cylinder bore with the end face of the other piston when the pistons are near top center locations in the bore; and,
the combustion chamber has an asymmetrical shape with respect to a chamber centerline that extends between diametrically opposing openings of the combustion chamber through which fuel is injected; wherein,
the asymmetrical shape includes a maximum distance R 1 from the chamber centerline to one side of the combustion chamber;
R 1 is positioned a distance L along the chamber centerline on either side of a midpoint of the centerline; and,
the asymmetrical shape is polar symmetric with respect to the midpoint of the centerline and provides clearance on a side of the combustion chamber centerline toward which swirl is directed, thereby giving a fuel plume space to entrain air in the presence of swirl, accommodating both fuel plume spreading and fuel plume movement in response to swirl.

2. The opposed-piston engine of claim 1 , in which the cylinder includes a pair of diametrically opposed fuel injector ports with which the opposed openings of the combustion chamber align when the pistons are near the respective top center locations.

3. The opposed-piston engine of claim 2 , in which the opposing openings provide a sightline between the fuel injector ports that extends without obstruction through the combustion chamber.

4. The opposed-piston engine of claim 3 , further including a fuel injector with a multi-hole nozzle mounted in each of the fuel injector ports.

5. The opposed-piston engine of claim 1 , in which the combustion chamber is defined between a bowl in the end surface of a first piston of the pair of pistons and inner walls of ridges that protrude from the end surface of a second piston of the pair of pistons, further in which the combustion chamber's asymmetrical shape is polar symmetric with respect to the centerline midpoint in a reference plane that is transverse to the longitudinal axis of the at least one cylinder and that bisects the combustion chamber.

6. The opposed-piston engine of claim 5 , in which the cylinder includes a pair of diametrically opposed fuel injector ports with which the opposed openings of the combustion chamber align when the pistons are near the respective top center locations.

7. The opposed-piston engine of claim 6 , in which the opposing openings provide a sightline between the fuel injector ports that extends without obstruction through the combustion chamber.

8. The opposed-piston engine of claim 7 , further including a fuel injector with a multi-hole nozzle mounted in each of the fuel injector ports.

9. An opposed-piston engine including at least one cylinder with a bore, piston-controlled exhaust and intake ports near respective ends of the cylinder, and a pair of pistons disposed in opposition in the bore, in which:
each piston has a crown with an end surface defining a combustion chamber in the cylinder bore with the end face of the other piston when the pistons are near top center locations in the bore; and,
the combustion chamber has an asymmetrical shape with respect to a chamber centerline that extends between diametrically opposing openings of the combustion chamber through which fuel is injected; wherein,
the asymmetrical shape includes a maximum distance R 1 from the chamber centerline to one side of the combustion chamber;
R 1 is positioned a distance L along the chamber centerline on either side of a midpoint of the centerline;
the asymmetrical shape is polar symmetric with respect to the midpoint of the centerline; and
the combustion chamber is defined between a first piston end surface on a first piston of the pair of pistons, the first piston end surface including a ridge having an inner wall that transitions to an elongate bowl and a second piston end surface on a second piston of the pair of pistons, the second piston end surface including a ridge having an inner wall that transitions to an elongate bowl.

10. The opposed-piston engine of claim 9 , in which the cylinder includes a pair of diametrically opposed fuel injector ports with which the opposed openings of the combustion chamber align when the pistons are near the respective top center locations.

11. The opposed-piston engine of claim 10 , in which the opposing openings provide a sightline between the fuel injector ports that extends without obstruction through the combustion chamber.

12. The opposed-piston engine of claim 11 , further including a fuel injector with a multi-hole nozzle mounted in each of the fuel injector ports.

13. A two-stroke, direct injection, opposed-piston engine including a cylinder with a bore, piston-controlled exhaust and intake ports near respective ends of the cylinder, and a pair of pistons disposed in opposition in the bore, in which each piston has a crown with an end surface and a sidewall, the end surface and sidewall meeting at a circular peripheral edge centered on an axis of the piston, and the end surface defining a combustion chamber in the cylinder bore with the end face of the other piston when the pistons are near top center locations in the bore; wherein,
the combustion chamber has an asymmetrical shape defined between first and second end surface ridges positioned on either side of a chamber centerline that extends between diametrically opposing points of the bore;
the asymmetrical shape includes a maximum distance R 1 from the chamber centerline to one side of the combustion chamber;
R 1 is positioned a distance L along the chamber centerline on either side of a centerline midpoint; and,
the asymmetrical shape has polar symmetry with respect to a point on a longitudinal axis of the bore in a plane that is transversal to the longitudinal axis and that bisects the combustion chamber and provides clearance on a side of the chamber centerline toward which swirl is directed, thereby giving a fuel plume space to entrain air in the presence of swirl, accommodating both fuel plume spreading and fuel plume movement in response to swirl.

14. The two-stroke, direct injection, opposed-piston engine of claim 13 , in which the combustion chamber is defined between a bowl in the end surface of a first piston of the pair of pistons and inner walls of ridges that protrude from the end surface of a second piston of the pair of pistons.

15. A two-stroke, direct injection, opposed-piston engine including a cylinder with a bore, piston-controlled exhaust and intake ports near respective ends of the cylinder, and a pair of pistons disposed in opposition in the bore, in which each piston has a crown with an end surface and a sidewall, the end surface and sidewall meeting at a circular peripheral edge centered on an axis of the piston, and the end surface defining a combustion chamber in the cylinder bore with the end face of the other piston when the pistons are near top center locations in the bore; wherein,
the combustion chamber has an asymmetrical shape defined between first and second end surface ridges positioned on either side of a chamber centerline that extends between diametrically opposing points of the bore;
the asymmetrical shape includes a maximum distance R 1 from the chamber centerline to one side of the combustion chamber;
R 1 is positioned a distance L along the chamber centerline on either side of a centerline m

Assignees

• Achates Power Inc

Inventors

• Abani Neerav
• Mackenzie Ryan G
• Venugopal Rishikesh

Classifications

• F02B23/066

  the injector being located substantially off-set from the cylinder centre axis · CPC title

• F02B23/0621

  Squish flow · CPC title

• F01B7/14

  acting on different main shafts · CPC title

• F02B23/0678

  Unconventional, complex or non-rotationally symmetrical shapes of the combustion space, e.g. flower like, having special shapes related to the orientation of the fuel spray jets · CPC title

• F02F3/00

  Pistons · CPC title