Minimizing oil leakage from rocking journal bearings of two-stroke cycle engines

Patent metadata

Field	Value
Publication number	US-9581187-B2
Application number	US-201514732531-A
Country	US
Kind code	B2
Filing date	Jun 5, 2015
Priority date	Jun 5, 2015
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

A rocking journal bearing is provided in a piston coupling mechanism of a two-stroke cycle engine. The bearing includes a sleeve and a wristpin constructed with two sets of eccentrically-disposed bearing surfaces which alternate in accepting a compressive load during an operational cycle of the bearing. The sleeve includes a network of grooves to transport oil to the bearing surfaces. Lubricating oil flow through the bearing is minimized by limiting provision of pressurized oil from the wristpin to the network of grooves to portions of the cycle when one or the other of the sets of bearing surfaces receives the compressive load.

First claim

The invention claimed is:

1. A rocking journal bearing for a two-stroke cycle engine, comprising:
a bearing sleeve including a generally cylindrical bearing surface with a plurality of axially-spaced, eccentrically-disposed surface segments separated by circumferential oil grooves in the bearing surface for transporting oil in a circumferential direction of the bearing surface;
a plurality of circumferentially-spaced, axial oil grooves in the bearing surface that run across the surface segments and intersect the circumferential oil grooves for transporting oil in an axial direction of the bearing surface;
a wristpin including a plurality of axially-spaced, eccentrically-disposed journal segments engaged for rocking oscillation with corresponding surface segments; and,
an oil-receiving space in the wristpin with oil outlet passages acting through the journal segments for delivering oil to the bearing surface; in which,
there are no oil outlet passages in the wristpin that are aligned with the circumferential oil grooves in the bearing surface; and,
at least one oil outlet passage in each journal segment is positioned to cross at least one axial oil groove during said rocking oscillation; wherein,
the plurality of journal segments includes a first journal segment formed in an intermediate portion of the wristpin, between two second journal segments and the two second journal segments are formed on opposite ends of the wristpin, on respective sides of the first journal segment;
positioning of a first oil outlet passage locates the first oil outlet passage in the first journal segment at a first arcuate distance from one side of a cut plane containing the longitudinal axis of the wristpin and a radius forming an axis of an oil inlet passage in the wristpin for transporting oil to the oil-receiving space; and,
positioning of two second oil outlet passages locates each second oil passage in a respective one of the second journal segments at a second arcuate distance from the opposite side of the cut plane;
in which the first and second arcuate distances are in opposite directions; and,
wherein, when a rotational position of the wristpin relative to the sleeve is at a load transfer point of the rocking journal bearing, the first and second oil outlet passages are positioned between first and second axial oil grooves, with the first oil outlet passage being relatively nearer to the first axial oil groove, and the second oil outlet passages being relatively nearer to the second axial oil groove.

2. A rocking journal bearing according to claim 1 , wherein, when the wristpin is at rotational position relative to the sleeve where first journal and surface segments are fully loaded, while second journal and surface segments are separated, the first oil outlet passage is aligned with the first axial oil groove for enabling oil to enter the first axial oil groove from the first oil outlet passage.

3. A rocking journal bearing according to claim 2 , in which the separation between the second journal and surface segments enables the second oil outlet passages to deliver oil to space between the second journal and surface segments.

4. A rocking journal bearing according to claim 1 , wherein, when the wristpin is at a rotational position relative to the sleeve where second journal and surface segments are fully loaded, while first journal and surface segments are separated, the second oil outlet passages are aligned with the second axial oil groove for enabling oil to enter the second axial oil groove from the second oil outlet passages.

5. A rocking journal bearing according to claim 4 , in which the separation between the first journal and surface segments enables the first oil outlet passage to deliver oil to space between the first journal and surface segments.

6. A rocking journal bearing for a two-stroke cycle engine, comprising:
a bearing sleeve including a generally cylindrical bearing surface with a plurality of axially-spaced, eccentrically-disposed surface segments separated by circumferential oil grooves in the bearing surface for transporting oil in a circumferential direction of the bearing surface;
a plurality of circumferentially-spaced, axial oil grooves in the bearing surface that run across the surface segments and intersect the circumferential oil grooves for transporting oil in an axial direction of the bearing surface;
a wristpin including a plurality of axially-spaced, eccentrically-disposed journal segments engaged for rocking oscillation with corresponding surface segments; and,
an oil-receiving space in the wristpin with oil outlet passages acting through the journal segments for delivering oil to the bearing surface; in which,
there are no oil outlet passages in the wristpin that are aligned with the circumferential oil grooves in the bearing surface; and,
at least one oil outlet passage in each journal segment is positioned to cross at least one axial oil groove during said rocking oscillation;
wherein the plurality of journal segments includes a first journal segment having a first centerline and two second journal segments sharing a second centerline that is offset from the first centerline, and the first journal segment is disposed between two second journal segments, in which:
positioning of a first oil outlet passage locates the first oil outlet passage in the first journal segment at a first arcuate distance from one side of a cut plane containing the longitudinal axis of the wristpin and a radius forming the axis of an oil inlet passage in the wristpin for transporting oil to the oil-receiving space;
positioning of two second oil outlet passages locates each second oil passage in a respective one of the second journal segments at a second arcuate distance from the opposite side of the cut plane; and,
the first and second arcuate distances are in opposite directions; and,
wherein, when a rotational position of the wristpin relative to the sleeve is at a load transfer point of the rocking journal bearing, the first and second oil outlet passages are positioned between first and second axial oil grooves, with the first oil outlet passage relatively nearer to the first axial oil groove, and the second oil outlet passages relatively nearer to the second axial oil groove.

7. A rocking journal bearing according to claim 6 , wherein, when the wristpin is at rotational position relative to the sleeve where first journal and surface segments are fully loaded, while second journal and surface segments are separated, the first oil outlet passage is aligned with the first axial oil groove for enabling oil to enter the first axial oil groove from the first oil outlet passage.

8. A rocking journal bearing according to claim 7 , in which the separation between the second journal and surface segments enables the second oil outlet passages to deliver oil to space between the second journal and surface segments.

9. A rocking journal bearing according to claim 6 , wherein, when the wristpin is at a rotational position relative to the sleeve where second journal and surface segments are fully loaded, while first journal and surface segments are separated, the second oil outlet passages are aligned with the second axial oil groove for enabling oil to enter the second axial oil groove from the second oil outlet passages.

10. A rocking journal bearing according to claim 9 , in which the separation between the first journal and surface segments enables the first oil outlet passage to deliver oil to space between the first journal and surface segments.

Assignees

• Achates Power Inc

Inventors

• Kessler John M
• Klyza Clark A

Classifications

• F16J1/14 Primary

  with connecting-rods, i.e. pivotal connections · CPC title

• F02B75/282 Primary

  the pistons having equal strokes · CPC title

• F01M2011/026

  for lubricating crankshaft bearings · CPC title

• F16C17/022

  with a pair of essentially semicircular bearing sleeves · CPC title

• F16J1/16

  with gudgeon-pin; Gudgeon-pins · CPC title