Cylinder bore for a cylinder housing of an internal combustion engine, and arrangement having a cylinder bore and a piston

Patent metadata

Field	Value
Publication number	US-11022063-B2
Application number	US-201615576274-A
Country	US
Kind code	B2
Filing date	May 20, 2016
Priority date	May 22, 2015
Publication date	Jun 1, 2021
Grant date	Jun 1, 2021

Abstract

A cylinder bore for a cylinder housing of an internal combustion engine may have a cylinder running surface, an upper reversal point and a lower reversal point at which a piston, which may be moved up and down in the cylinder bore and may have piston rings and a piston skirt, may reach a speed which approaches zero during engine operation. The cylinder bore may also have a region between the upper reversal point and the lower reversal point at which the piston may reach a maximum speed during engine operation. The cylinder bore may further have at least two circumferential depressions formed within the region, the at least two circumferential depressions each having a diameter that may be greater than a diameter of the cylinder bore above the region and below the region.

First claim

The invention claimed is:

1. A cylinder bore for a cylinder housing of an internal combustion engine, comprising:
a cylinder running surface;
an upper reversal point and a lower reversal point at which a piston, which is moved up and down in the cylinder bore and has piston rings and a piston skirt, reaches a speed which approaches zero during engine operation;
a region between the upper reversal point and the lower reversal point at which the piston reaches a maximum speed during engine operation;
at least two circumferential depressions formed within the region, the at least two circumferential depressions each having a diameter greater than a diameter of the cylinder bore above the region and below the region;
wherein a roughness of the cylinder running surface in a region of the at least two circumferential depressions is less than in regions outside the at least two circumferential depressions; and
wherein the diameters of the at least two circumferential depressions are greater by 5 μm to 30 μm than at least one of the diameter of the cylinder bore above the region and the diameter of the cylinder bore below the region.

2. The cylinder bore as claimed in claim 1 , wherein the diameters of the at least two circumferential depressions are the same.

3. The cylinder bore as claimed in claim 1 , wherein the diameter of the cylinder bore above the region and below the region are the same.

4. The cylinder bore as claimed in claim 1 , wherein the diameter of the cylinder bore above the region and below the region are constant over axial heights of the cylinder bore above the region and below the region.

5. The cylinder bore as claimed in claim 1 , wherein a roughness of the cylinder running surface in a region of the at least two circumferential depressions is less than 3 μm.

6. The cylinder bore as claimed in claim 5 , wherein the roughness of the cylinder running surface in the region of the at least two circumferential depressions is less than 1 μm.

7. The cylinder bore as claimed in claim 6 , wherein the roughness of the cylinder running surface in the region of the at least two circumferential depressions is less than 0.5 μm.

8. The cylinder bore as claimed in claim 1 , wherein the cylinder running surface has, at least partially in a region outside the at least two circumferential depressions, a hardness greater than in a region of the at least two circumferential depressions.

9. The cylinder bore as claimed in claim 1 , wherein the at least two circumferential depressions merge into adjacent portions of the cylinder running surface via a curved transition.

10. The cylinder bore as claimed in claim 1 , wherein:
an intermediate region of the cylinder running surface extends axially between the at least two circumferential depressions; and
the intermediate region of the cylinder running surface includes a max speed point at which the piston reaches the maximum speed during engine operation.

11. An arrangement for a cylinder housing of an internal combustion engine, comprising:
a piston having piston rings and a piston skirt; and
a cylinder bore in which the piston is moved up and down, the cylinder bore having:
a cylinder running surface;
an upper reversal point and a lower reversal point at which the piston reaches a speed which approaches zero during engine operation;
a region between the upper reversal point and the lower reversal point at which the piston reaches a maximum speed during engine operation; and
at least two circumferential depressions formed within the region, the at least two circumferential depressions each having a diameter greater than a diameter of the cylinder bore above the region and below the region;
wherein at least one piston ring, at least in a contact region with the cylinder running surface, includes one of a CrN coating and a DLC coating produced by a PVD process; and
wherein the cylinder running surface has, at least partially in a region outside the at least two circumferential depressions, a hardness greater than in a region of the at least two circumferential depressions.

12. The arrangement as claimed in claim 11 , wherein at least the piston skirt includes a steel material.

13. The arrangement as claimed in claim 11 , wherein the arrangement is configured for an internal combustion engine for motor vehicles having at least two cylinders.

14. The arrangement as claimed in claim 11 , wherein the diameter of the cylinder bore above the region and below the region are constant over axial heights of the cylinder bore above the region and below the region.

15. The arrangement as claimed in claim 11 , wherein the diameters of the at least two circumferential depressions are greater by 5 μm to 30 μm than at least one of the diameter of the cylinder bore above the region and the diameter of the cylinder bore below the region.

16. The arrangement as claimed in claim 11 , wherein a roughness of the cylinder running surface in a region of the at least two circumferential depressions is less than in regions outside the at least two circumferential depressions.

17. The arrangement as claimed in claim 11 , wherein a roughness of the cylinder running surface in a region of the at least two circumferential depressions is less than 3 μm.

18. An arrangement for a cylinder housing of an internal combustion engine, comprising a piston including a plurality of piston rings and a piston skirt, and a cylinder bore in which the piston is disposed, the cylinder bore including:
a cylindrical interior running surface having an upper reversal point and a lower reversal point between which the piston axially slides within the piston bore during engine operation; and
at least two circumferential depressions disposed in a region between the upper reversal point and the lower reversal point at which the piston reaches a maximum speed during engine operation;
wherein the at least two circumferential depressions each have a diameter that is 5 μm to 30 μm greater than a diameter of the cylinder bore above the region and below the region; and
wherein the running surface has a surface roughness of 3 μm Rz or less in a region of the at least two circumferential depressions.

19. The arrangement as claimed in claim 18 , wherein: an intermediate region of the cylindrical running surface extends axially between the at least two circumferential depressions; the piston is disposed within the cylinder bore with play between the piston and the cylindrical running surface; and when aligned with the intermediate region of the cylindrical running surface, at least one of the plurality of piston rings is in tight sliding contact with the intermediate region of the cylindrical running surface such that the piston is substantially prevented from deflecting and striking the cylindrical running surface.

Assignees

• Mahle Int Gmbh

Inventors

• Bischofberger Ulrich
• Gaiselmann Stefan

Classifications

• F02F1/004 Primary

  Cylinder liners (F02F1/08, F02F1/16 take precedence) · CPC title

• F02F1/18

  Other cylinders · CPC title

• F02F1/20 Primary

  characterised by constructional features providing for lubrication · CPC title

• F02F3/0084

  the pistons being constructed from specific materials · CPC title