Piston assembly with weld support

• US 9,631,576 B2
• Filed: 02/21/2014
• Issued: 04/25/2017
• Est. Priority Date: 02/22/2013
• Status: Expired due to Fees

• Current Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Original Assignee: Mahle International GmbH (MAHLE-STIFTUNG GmbH)
• Inventors: Lapp, Michael T., Gabriel, Dieter
• Primary Examiner(s): Leslie, Michael
• Application Number:
  US14/186,651
• Publication Number:
  US 20140238232A1
• Time in Patent Office: 1,159 Days
• Field of Search: 92186, 92231
• CPC Class Codes: B23K 2101/003 Pistons
• CPC Class Codes: B23K 2103/10 Aluminium or alloys thereof
• CPC Class Codes: B23K 26/28 of curved planar seams
• CPC Class Codes: B23K 26/32 taking account of the properties of the material involved
• CPC Class Codes: F02F 2003/0061 by welding
• CPC Class Codes: F02F 3/003 the parts being connected by casting, brazing, welding or clamping
• CPC Class Codes: F02F 3/16 having cooling means
• CPC Class Codes: F02F 3/22 the fluid being liquid
• CPC Class Codes: Y10T 29/49249 Piston making

Abstract

Exemplary piston assemblies and methods of making the same are disclosed. An exemplary piston may include a piston body defining a piston axis, the piston body having a skirt and forming a lower surface of a cooling gallery. The body may include radially inner and outer body mating surfaces. The piston may further include a cooling gallery ring cooperating with the piston body to form the cooling gallery. The piston body and cooling gallery ring may be joined together along radially inner and radially outer interface regions to form a generally one-piece piston assembly. In some exemplary approaches, mating surfaces of the body and ring may be positioned adjacent a support surface configured to inhibit or prevent weld spatter formed in a process joining the ring and body from the cooling gallery.

Claims

1. A method, comprising:

providing a piston body that forms an entire upper combustion bowl surface, which is free from welds, the piston body forming a first portion of a cooling gallery, the piston body including radially inner and radially outer body mating surfaces and defining a piston axis;

assembling a cooling gallery ring with the piston body, the cooling gallery ring forming a second portion of the cooling gallery, the cooling gallery ring including a radially inner ring mating surface and a radially outer ring mating surface;

forming the cooling gallery with the first and second portions by laser welding the piston body to the cooling gallery ring along a radially inner interface region, the radially inner interface region including the radially inner mating surfaces of the piston body and the cooling gallery ring; and

laser welding the piston body to the cooling gallery ring along a radially outer interface region, the radially outer interface region including the radially outer mating surfaces of the piston body and cooling gallery ring;

wherein, at the radially inner interface region, the piston body includes a body step portion formed on the piston body being axially offset to and extending radially from the radially inner body mating surface, the body step portion comprising a laterally extending surface that faces the cooling gallery ring, and the body step portion forming a part of the cooling gallery; and

wherein, at the radially outer interface region, the cooling gallery ring includes a cooling gallery step portion being radially offset to and axially extending from the radially outer ring mating surface, a vertically extending surface formed on the cooling gallery step portion that faces the piston body, and the cooling gallery step portion forms a part of the cooling gallery.

2. The method of claim 1, wherein the laser welding includes directing a weld laser substantially parallel to the piston axis toward the radially mating surfaces of the piston body and cooling gallery ring.

3. The method of claim 1, wherein the laser welding includes directing a weld laser in a direction toward the radially outer mating surfaces of the piston body and cooling gallery ring, the direction defining a non-parallel angle with respect to the piston axis.

4. The method of claim 1, wherein the piston body includes a skirt configured to interface with an engine bore surface.

5. The method of claim 1, further comprising heating at least one of the piston body and the cooling gallery ring prior to the laser welding.

6. The method of claim 1, wherein the body step portion includes a spatter trap configured to receive weld spatter, the spatter trap defining an enclosed volume adjacent to a weld site associated with one of the radially inner and outer interface regions.

7. The method of claim 1, wherein the piston body and cooling gallery ring are each formed of an aluminum material.

8. The method of claim 1, wherein the cooling gallery ring step portion is formed from a gallery ring radial surface and the vertically extending surface that is radially external to the gallery ring radial surface, and the piston body includes a piston body radial surface that faces radially inward and is engaged against the vertically extending surface.

9. A piston assembly, comprising:

a piston body having a top surface and having formed therein an uninterrupted unitary upper combustion bowl surface, the piston body having a skirt and forming a first portion of a cooling gallery, the piston body including radially inner and radially outer body mating surfaces and defining a piston axis; and

a cooling gallery ring forms a second portion of the cooling gallery and includes a radially inner ring mating surface abutted along a radially inner interface region with the radially inner body mating surface, the cooling gallery ring includes a radially outer ring mating surface abutted along a radially outer interface region with the radially outer body mating surface such that the cooling gallery is substantially enclosed as the first and second portions;

wherein the piston body and cooling gallery ring are welded together along the radially inner and radially outer interface regions;

wherein, at the radially inner interface region, the piston body includes a body portion formed on the piston body being axially offset to and extending radially from the radially inner body mating surface, the body step portion comprising a laterally extending surface that faces the cooling gallery ring, and the body step portion forming a part of the cooling gallery; and

wherein, at the radially outer interface region, the cooling gallery ring includes a cooling gallery step portion being radially offset to and axially extending from the radially outer ring mating surface, a vertically extending surface formed on the cooling gallery step portion that faces the piston body, and the cooling gallery step portion forms a part of the cooling gallery.

10. The piston assembly of claim 9, wherein the body step portion includes a spatter trap configured to receive weld spatter, and the spatter trap defines an enclosed volume adjacent to a weld site associated with one of the radially inner and outer interface regions.

11. The piston assembly of claim 9, further comprising a ring insert received within a piston ring groove, the ring insert defining a cavity configured to retain a piston ring.

12. The piston assembly of claim 9, wherein the cooling gallery ring step portion is formed from a gallery ring radial surface and the vertically extending surface that is radially external to the gallery ring radial surface, and the piston body includes a piston body radial surface that faces radially inward and is engaged against the vertically extending surface.

13. A piston assembly, comprising:

a piston body having a top surface and having formed in the top surface an entire combustion bowl within the piston body, the piston body forms a first portion of a cooling gallery, the piston body includes radially inner and radially outer body mating surfaces, and the piston body forms a piston axis; and

a cooling gallery ring forms a second portion of the cooling gallery, the cooling gallery ring includes a radially inner ring mating surface abutted along a radially inner interface region with the radially inner body mating surface, the cooling gallery ring includes a radially outer ring mating surface abutted along a radially outer interface region with the radially outer body mating surface such that the cooling gallery is substantially enclosed;

wherein, at the radially inner interface region, the piston body includes a body step portion formed on the piston body being axially offset to and extending radially from the radially inner body mating surface, the body step portion comprising a laterally extending surface that faces the cooling gallery ring, and the body step portion forming a part of the cooling gallery; and

wherein, at the radially outer interface region, the cooling gallery ring includes a cooling gallery step portion being radially offset to and axially extending from the radially outer ring mating surface, a vertically extending surface formed on the cooling gallery step portion that faces the piston body, and the cooling gallery step portion forms a part of the cooling gallery.

14. The piston assembly of claim 13, wherein the entire combustion bowl is a unitary surface within the top surface of the piston and the entire combustion bowl surface is free from welds.

15. The piston assembly of claim 13, wherein the cooling gallery ring step portion is formed from a gallery ring radial surface and the vertically extending surface that is radially external to the gallery ring radial surface, and the piston body includes a piston body radial surface that faces radially inward and is engaged against the vertically extending surface.