Piston for an internal combustion engine and production method

Patent metadata

Field	Value
Publication number	US-11680540-B2
Application number	US-202117505620-A
Country	US
Kind code	B2
Filing date	Oct 19, 2021
Priority date	Oct 20, 2020
Publication date	Jun 20, 2023
Grant date	Jun 20, 2023

Abstract

A piston for an internal combustion engine may include a piston crown, a piston body, and a ring portion. The piston body may have a radially outermost piston outer surface, which may emanate from the piston crown and extend axially and in a circumferential direction. The ring portion may be disposed axially spaced apart from the piston crown. The ring portion may extend axially and in the circumferential direction. The ring portion may include a ring carrier with a ring groove configured to receive a piston ring. The ring portion may further include a radially outer ring portion outer surface that extends in the circumferential direction. The ring portion outer surface may be disposed radially to an inside relative to the piston outer surface. The piston outer surface may extend elliptically in the circumferential direction. The ring portion outer surface may extend rotation-symmetrically in the circumferential direction.

First claim

The invention claimed is:

1. A piston for an internal combustion engine, comprising:
a piston crown disposed at a front side in an axial direction;
a piston body having a radially outermost piston outer surface, which emanating from the piston crown extends axially and in a circumferential direction;
a ring portion disposed axially spaced apart from the piston crown, the ring portion extending axially and in the circumferential direction, the ring portion including a ring carrier with a ring groove configured to receive a piston ring;
the ring portion further including a radially outer ring portion outer surface that extends in the circumferential direction;
the ring portion outer surface disposed radially to an inside relative to the piston outer surface;
wherein the piston outer surface extends elliptically in the circumferential direction;
wherein the ring portion outer surface extends rotation-symmetrically in the circumferential direction; and
wherein an offset distance between the ring portion outer surface and the piston outer surface is 0.01 mm to 0.1 mm.

2. The piston according to claim 1 , wherein:
the piston body is composed of a light metal;
the ring carrier is received in the ring portion in the piston body and is composed of a material having a greater hardness than the piston body;
the ring carrier is disposed axially spaced apart from the piston outer surface on both sides; and
the ring carrier is arranged radially to the inside relative to the piston outer surface.

3. The piston according to claim 1 , wherein:
the ring groove has a radially inner base; and
a receiving depth of the ring groove extending radially from the inner base to the ring portion outer surface is constant in the circumferential direction.

4. The piston according to claim 1 , wherein:
the ring groove has a radially inner base; and
a ring groove depth of the ring groove extending radially from the inner base to the piston outer surface varies in the circumferential direction.

5. The piston according to claim 1 , wherein:
the ring groove is delimited radially outside by two edges disposed axially opposite one another; and
at least one of the two edges includes a chamfer.

6. The piston according to claim 1 , wherein a radially outward facing offset surface of the piston body and a radially outward facing surface of the ring carrier are arranged flush with one another and collectively define the ring portion outer surface.

7. The piston according to claim 6 , wherein an end of the offset surface of the piston body is axially aligned with and contacts an end of the radially outward facing surface of the ring carrier.

8. The piston according to claim 7 , wherein the radially outward facing surface of the ring carrier and the offset surface of the piston body extend parallel to the axial direction.

9. The piston according to claim 6 , wherein:
the ring carrier is structured independently and separately from the piston body; and
the ring carrier is at least partially embedded in the ring portion of the piston body.

10. The piston according to claim 6 , wherein:
the piston body is composed of a light metal; and
the ring carrier is received in the ring portion in the piston body and is composed of a material having a greater hardness than the piston body.

11. A method for producing a piston including a piston crown disposed at a front side in an axial direction, a piston body having a radially outermost piston outer surface, which emanating from the piston crown extends axially and in a circumferential direction, and a ring portion disposed axially spaced apart from the piston crown, the ring portion extending axially and in the circumferential direction, the ring portion including a ring carrier with a ring groove configured to receive a piston ring, the method comprising:
providing a blank;
producing a preform via rotation-symmetrically introducing a radial recess into the blank;
forming a radially outer ring portion outer surface in the ring portion via rotation-symmetrically introducing the ring groove into the recess, the ring portion outer surface extending rotation-symmetrically in the circumferential direction and disposed radially to an inside relative to the piston outer surface;
elliptically machining the preform such that the piston outer surface extends elliptically in the circumferential direction; and
wherein an offset distance between the ring portion outer surface and the piston outer surface is 0.01 mm to 0.1 mm.

12. The method according to claim 11 , further comprising introducing a chamfer on at least one radially outer edge of the ring groove.

13. The method according to claim 12 , further comprising:
providing a combination tool including a grooving knife and a chamfering knife, the chamfering knife arranged following the grooving knife and connected to the grooving knife, the grooving knife including a radial grooving knife front side protruding over a radial chamfering front side of the chamfering knife;
arranging the combination tool radially outside of the preform such that the grooving knife front side and the chamfering front side face the recess;
performing a rotation-symmetrical relative turning movement between the preform and the combination tool; and
wherein introducing the ring groove and introducing the chamfer includes moving the combination tool radially towards the preform while performing the turning movement such that, during the turning movement, initially the grooving knife and subsequently the chamfering knife enter the recess, the grooving knife introduces the ring groove into the recess, and the chamfering knife introduces the chamfer on the at least one radially outer edge of the ring groove.

14. The method according to claim 11 , wherein:
providing the blank includes producing the blank via a casting method; and
producing the blank includes placing the ring carrier in a casting mould such that the ring carrier will be arranged in the ring portion of the piston.

15. A piston for an internal combustion engine, comprising:
a piston crown;
a piston body having a piston outer surface facing radially outward and extending from the piston crown in an axial direction, the piston outer surface having an elliptical-shaped cross-sectional profile perpendicular to the axial direction;
a ring carrier disposed in the piston body, the ring carrier including a ring groove configured to receive a piston ring;
a ring portion defined at least partially by the piston body and the ring carrier, the ring portion disposed axially spaced apart from the piston crown, the ring portion extending in the axial direction and in a circumferential direction;
the ring portion having a ring portion outer surface facing radially outward and extending rotation-symmetrically in the circumferential direction;
wherein the ring portion outer surface is disposed offset from the piston outer surface in a radially inward direction;
wherein a radially outward facing offset surface of the piston body and a radially outward facing surface of the ring carrier are arranged flush with one another and collectively define the ring portion outer surface; and
wherein an offset distance between the ring portion outer surface and the piston outer surface is 0.01 mm to 0.1 mm.

16. The piston according to claim 15 , wherein an end of the offset surface of the piston body is axially aligned with and contacts an end of the radially outward facing surface of the ring carrier.

17. The piston according to claim 15 , wherein the radially outward facing su

Assignees

• Mahle Int Gmbh

Inventors

• Bechtold Peter
• Biswurm Michael

Classifications

• F02F2200/00

  Manufacturing · CPC title

• F02F3/28 Primary

  Other pistons with specially-shaped head · CPC title

• F02F3/00 Primary

  Pistons · CPC title

• F16J9/22 Primary

  Rings for preventing wear of grooves or like seatings · CPC title

• F02F3/02

  having means for accommodating or controlling heat expansion · CPC title