Oil retention in the bore/piston interfaces of ported cylinders in opposed-piston engines

Patent metadata

Field	Value
Publication number	US-9482153-B2
Application number	US-93119911-A
Country	US
Kind code	B2
Filing date	Jan 26, 2011
Priority date	Jan 26, 2011
Publication date	Nov 1, 2016
Grant date	Nov 1, 2016

Abstract

An opposed piston engine includes at least one cylinder with a bore surface and longitudinally-spaced exhaust and intake ports that open through the sidewall of the cylinder. A pair of opposed pistons is disposed in the cylinder for sliding movement along the bore surface. An oil-retaining surface texture pattern in an interface between the pistons and the bore surface extends in a longitudinal direction of the cylinder, aligned with bridges of at least one port. The surface texture pattern includes a plurality of separate recesses on an outside surface of a skirt of each piston. Alternatively, or in addition, the surface texture pattern includes a plurality of separate recesses extending in a longitudinal direction of the cylinder, aligned with bridges of at least one port.

First claim

The invention claimed is:

1. An opposed piston engine having at least one cylinder with a bore surface and longitudinally-spaced exhaust and intake ports, and a pair of opposed pistons disposed in the cylinder for sliding movement along the bore surface, in which an oil-retaining surface texture pattern in an interface between the pistons and the bore surface extends in a longitudinal direction of the cylinder between a top ring reversal zone where the sliding velocity of a ring mounted to a piston reaches zero when the piston is near a top dead center position and a bottom ring reversal zone where the sliding velocity of the ring reaches zero when the piston is near a bottom dead center position, and in which the surface texture pattern comprises at least one row of separate recesses on the bore surface aligned with a bridge of at least one port.

2. The opposed piston engine of claim 1 , in which an end portion of the at least one row is positioned in a reversal zone of the bore surface.

3. The opposed piston engine of claim 1 , in which the at least one row is no wider than a the bridge with which it is aligned.

4. The opposed piston engine of claim 1 , in which the reversal zone is positioned near the middle area of the bore surface.

5. A cylinder mechanism including a cylinder with a bore surface and longitudinally-spaced exhaust and intake ports near respective ends and a pair of opposed pistons disposed in the cylinder for sliding movement along the bore surface, in which a first oil-collecting surface texture pattern in an interface between an exhaust piston and the bore surface extends in a longitudinal direction of the cylinder, between respective top dead center (TDC) and bottom dead center (BDC) reversal zones of the exhaust piston and aligned with a bridge of the exhaust port, and a second oil-collecting surface texture pattern in an interface between an intake piston and the bore surface extends in a longitudinal direction of the cylinder, between respective TDC and BDC reversal zones of the intake piston and aligned with a bridge of the intake port.

6. The cylinder mechanism of claim 5 , in which the first surface texture pattern includes at least one row of separate recesses on an outside surface of a skirt of the exhaust piston, each row extending in a longitudinal direction of the exhaust piston, and the second surface texture includes at least one row of separate recesses on an outside surface of a skirt of the intake piston, each row extending in a longitudinal direction of the intake piston.

7. The cylinder mechanism of claim 6 , in which each texture pattern is no wider than a bridge with which it is aligned.

8. The cylinder mechanism of claim 7 , in which each row includes a first end near a piston ring location.

9. The cylinder mechanism of claim 6 , in which the surface texture pattern includes a plurality of rows of separate recesses in an outside surface of a skirt of each piston, and for the exhaust piston, each row extends in a longitudinal direction of the exhaust piston and is disposed at a circumferential location of the piston skirt that corresponds to a location of a bridge of the exhaust port, and for the intake piston, each row extends in a longitudinal direction of the intake piston and is disposed at a circumferential location of the piston skirt that corresponds to a location of a bridge of the intake port.

10. The cylinder mechanism of claim 9 , in which each row includes a first end near a piston ring location.

11. The cylinder mechanism of claim 9 , in which each recess of a plurality of the recesses has a cross-sectional configuration that varies stepwise in depth in opposing circumferential directions of a skirt from a central portion of the recess.

12. The cylinder mechanism of claim 5 , in which the surface texture pattern includes at least two rows of separate recesses on the bore surface, a first row extending from the exhaust piston TDC reversal zone toward the exhaust port, and a second row extending from the intake piston TDC reversal zone toward the intake port.

13. The cylinder mechanism of claim 12 , in which the exhaust piston TDC reversal zone and the TDC intake piston reversal zone are separated by the middle area of the bore surface.

14. A method of lubricating an opposed piston engine having at least one cylinder with a bore surface and longitudinally-spaced exhaust and intake ports, and a pair of opposed pistons disposed in the cylinder for sliding movement along the bore surface, by transporting oil into the bore on surfaces of the pistons, and retaining the oil in a surface texture pattern in the bore surface that extends in a longitudinal direction of the cylinder, between respective top dead center and bottom dead center reversal zones of at least one of the opposed pistons.

15. The method of claim 14 , in which retaining oil in a surface texture pattern includes retaining the oil in at least one row of separate recesses on an outside surface of a skirt of each piston that extends in a longitudinal direction of the piston in alignment with at least one bridge of at least one port.

16. The method of claim 14 , in which retaining oil in a surface texture pattern includes retaining the oil in at least one row of separate recesses on the bore surface in alignment with at least one bridge of at least one port.

17. A method of operating an opposed-piston engine including at least one cylinder with a bore surface and longitudinally-spaced exhaust and intake ports near respective ends and a pair of opposed pistons disposed in the cylinder for sliding movement along the bore surface, by retaining oil in a first row of recesses in an interface between an exhaust piston and the bore surface that extends in a longitudinal direction of the cylinder, between respective top dead center (TDC) and bottom dead center (BDC) reversal zones of the exhaust piston and aligned with a bridge of the exhaust port, and retaining oil in a second row of recesses in an interface between an intake piston and the bore surface that extends in a longitudinal direction of the cylinder, between respective TDC and BDC reversal zones of the intake piston and aligned with a bridge of the intake port.

18. The method of claim 17 , in which retaining oil in a first row of recesses includes retaining oil in at least one row of recesses on a skirt surface of the exhaust piston, and retaining oil in a second row of recesses includes retaining oil in at least one row of recesses on a skirt surface of the intake piston.

19. The method of claim 17 , in which retaining oil in a first row of recesses includes retaining oil in at least one row of recesses on a bore surface of the cylinder extending toward the exhaust port, and retaining oil in a second row of recesses includes retaining oil in at least one row of recesses on a bore surface of the cylinder extending toward the intake port.

Assignees

• Bethel Steven J
• Callahan Brian J
• Wagner Bryant A
• Achates Power Inc

Inventors

• Bethel Steven J
• Callahan Brian J
• Wagner Bryant A

Classifications

• F02F3/027

  the skirt wall having cavities · CPC title

• F02B75/282 Primary

  the pistons having equal strokes · CPC title

• F02F1/186

  for use in engines with two or more pistons reciprocating within same cylinder · CPC title

• F02F1/20

  characterised by constructional features providing for lubrication · CPC title