Piston for internal combustion engine

Patent metadata

Field	Value
Publication number	US-9228530-B2
Application number	US-201414204732-A
Country	US
Kind code	B2
Filing date	Mar 11, 2014
Priority date	Mar 21, 2013
Publication date	Jan 5, 2016
Grant date	Jan 5, 2016

Abstract

A piston for an internal combustion engine comprises a crown, a skirt section extending from the crown, and an oil ring groove. The piston further comprises a drain hole and a cooling channel. The drain hole extends from the oil ring groove to an inside space of the piston. The cooling channel is formed in the crown at a level above the oil ring groove, and arranged to covey a cooling oil. The cooling channel includes a channel segment which is located near the drain hole and which is formed to have a sectional shape avoiding the drain hole.

First claim

What is claimed is:

1. A piston for an internal combustion engine, the piston comprising:
a crown including a crown surface;
a skirt section extending from an outside circumference of the crown;
an oil ring groove formed in an outside circumference of the crown;
a drain hole extending through a bottom wall of the oil ring groove and connecting the oil ring groove with an inside space of the piston, the drain hole being structurally configured to at least discharge oil away from the crown; and
a cooling channel formed, in a shape of a circular ring, in the crown at a position between the crown surface and the oil ring groove, and arranged to convey a cooling oil;
the cooling channel including a channel segment located near the drain hole and a main passage segment connected with the channel segment to form a circumferentially extending continuous fluid passage, the channel segment being formed to have a cross sectional shape which is offset from a cross sectional shape of the main passage segment and which is shaped to avoid the drain hole.

2. The piston as recited in claim 1 , wherein the drain hole extends in a direction substantially perpendicular to a piston axial line, from a bottom surface of the oil ring groove to the inside space of the piston, and the crown includes a thinned portion in which the drain hole is opened to the inside space.

3. The piston as recited in claim 2 , wherein the channel segment is formed in a region in which the skirt section is formed.

4. The piston as recited in claim 1 , wherein the channel segment is formed in each of first and second regions, the first region being a region in which a first piston skirt on a thrust side is formed, the second region being a region in which a second piston skirt on an anti-thrust side is formed, the first and second piston skirts being portions included in the skirt section.

5. The piston as recited in claim 1 , wherein an inside circumferential surface of the channel segment is connected smoothly with an inside circumferential surface of the main passage segment.

6. The piston as recited in claim 5 , wherein a cross sectional area of the channel segment is substantially equal to a cross sectional area of the main passage segment.

7. The piston as recited in claim 6 , wherein a width in a direction perpendicular to the piston axis, of the channel segment is greater than a width in the direction perpendicular to the piston axis, of the main passage segment.

8. The piston as recited in claim 6 , wherein a length in a piston axial direction, of the channel segment is smaller than a length in the piston axial direction, of the main passage segment.

9. The piston as recited in claim 5 , wherein an uppermost portion of the inside circumferential surface of the channel segment is located at a height substantially equal to a height of an uppermost portion of the main passage segment.

10. The piston as recited in claim 9 , wherein a width in a direction perpendicular to the piston axis, of the channel segment is substantially equal to a width in the direction perpendicular to the piston axis, of the main passage segment.

11. The piston as recited in claim 9 , wherein a width in a direction perpendicular to the piston axis, of the channel segment is greater than a width in the direction perpendicular to the piston axis, of the main passage segment.

12. The piston as recited in claim 5 , wherein a cross sectional area of the channel segment is smaller than a cross sectional area of the main passage segment.

13. The piston as recited in claim 12 , wherein the main passage segment has an elongated cross sectional shape elongated in a piston axial direction.

14. The piston as recited in claim 1 , wherein the drain hole extends in a direction slightly inclined with respect to a direction perpendicular to a piston axis.

15. The piston as recited in claim 1 , wherein the oil ring groove is defined by upper and lower side wall surfaces confronting each other in an axial direction of the piston, and a bottom wall surface connecting the upper and lower side surfaces to form an approximately rectangular cross sectional shape; and the drain hole extends substantially in parallel to the upper and lower side surfaces.

16. The piston as recited in claim 1 , wherein the channel segment is deviated toward the crown surface in an axial direction of the piston.

17. The piston as recited in claim 1 , wherein the cooling channel includes a main passage segment and the channel segment which is connected with the main passage segment and which has a cross sectional area substantially equal to a cross sectional area of the main passage segment; and the channel segment is deviated toward the crown surface in an axial direction of the piston.

18. A piston for an internal combustion engine, the piston comprising:
a crown including a crown surface;
a skirt section extending from an outside circumference of the crown;
an oil ring groove formed in an outside circumference of the crown;
a drain hole extending through a bottom wall of the oil ring groove and connecting the oil ring groove with an inside space of the piston, the drain hole being structurally configured to at least discharge oil away from the crown; and
a cooling channel formed, in a shape of a circular ring having offset cross-sectional shapes, in the crown at a position between the crown surface and the oil ring groove, and arranged to convey a cooling oil;
the cooling channel including a channel segment located near the drain hole and a main passage segment connected with the channel segment to form a circumferentially extending continuous fluid passage, the channel segment extending from an upper end to a lower end in a downward direction away from the crown surface, the lower end of the channel segment being offset in an upward direction toward the crown surface to avoid the drain hole, above a lower end of the main passage segment.

19. The piston as recited in claim 18 , wherein a distance of the channel segment from an upper side surface of the oil ring groove is equal to or greater than approximately 3 mm, the upper side surface of the oil ring groove facing in the downward direction away from the crown surface toward a lower side surface defining the oil ring groove between the upper and lower side surfaces.

20. A piston for an internal combustion engine, the piston comprising:
a crown including a crown surface;
a skirt section including a pair of piston skirts extending downwards from an outside circumference of the crown;
an oil ring groove formed in an outside circumference of the crown;
a drain hole extending through a bottom wall of the oil ring groove and connecting the oil ring groove with an inside space of the piston; and
an annular cooling channel formed in the crown, at a level above the oil ring groove, and arranged to convey to cooling oil;
the cooling channel including two of the channel segments extending circumferentially, respectively, in two skirt forming regions in which the piston skirts are formed respectively, and two main passage segments extending circumferentially, respectively, in two apron forming regions each of which is located circumferentially between the skirt forming regions;
the channel segments and the main passage segments having offset cross-sectional shapes and being arranged alternately in a circle and connected end to end to form a single continuous annular passage composed of the channel segments and the main passage segments;
each of the main passage segments bei

Assignees

• Hitachi Automotive Systems Ltd
• Hitachi Automotive Systems Ltd

Inventors

• Kodama Youichi
• Hamada Hiroaki

Classifications

• F02F3/22 Primary

  the fluid being liquid · CPC title

• F16J1/09

  with means for guiding fluids (F16J1/08 takes precedence) · CPC title