Method of making a piston

• US 7,721,431 B2
• Filed: 01/16/2008
• Issued: 05/25/2010
• Est. Priority Date: 08/02/2000
• Status: Expired due to Fees

• Current Assignee: David James Tharratt, David Thornton Pindar, Duncan Parker, Gillian Hume, Roger James Jones
• Original Assignee: David James Tharratt, David Thornton Pindar, Duncan Parker, Gillian Hume, Roger James Jones
• Inventors: Pindar, David Thornton, Parker, Duncan, Jones, Roger James, Hume, Gillian, Tharratt, David James
• Primary Examiner(s): CHANG, RICK KILTAE
• Application Number:
  US12/015,196
• Publication Number:
  US 20080110335A1
• Time in Patent Office: 860 Days
• Field of Search: 298/880.42, 298/880.44, 922/19, 123/193.4
• US Class Current: 29/888.042
• CPC Class Codes: F02B 23/0672 Omega-piston bowl, i.e. the combustion space having a central projection pointing towards the cylinder head and the surrounding wall being inclined towards the cylinder center axis the surrounding wall being exactly vertical F02B23/0696
• CPC Class Codes: F02F 2200/04 Forging of engine parts
• CPC Class Codes: F02F 3/003 the parts being connected by casting, brazing, welding or clamping
• CPC Class Codes: F02F 3/22 the fluid being liquid
• CPC Class Codes: F05C 2201/021 Aluminium
• CPC Class Codes: F05C 2251/042 Expansivity
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y10T 29/49249 Piston making
• CPC Class Codes: Y10T 29/49252 Multi-element piston making
• CPC Class Codes: Y10T 29/49256 with assembly or composite article making

Abstract

An engine piston is manufactured by assembling an outer shell, comprising a crown and tubular side wall in which a ring groove region and skirt are defined, with a plate-like mounting member and bonding them together by brazing or welding. The mounting member is located within the tubular side wall displaced axially from the crown and is bonded near, but displaced radially from, its centre to the crown and at its periphery to the side wall at the end of the ring groove region. The mounting member carries gudgeon pin boss means facing away from the crown. The outer shell is formed by extrusion or the like that permits minimal wall thickness and the bonded structure is of light weight but great strength and stiffness, particularly in the ring groove region. A combustion bowl formed in the crown facilitates bonding to the mounting member and defines with the mounting member an annular cooling chamber adjacent the ring groove region and crown.

Claims

1. A method of making an engine piston comprising forming an outer shell part comprising a crown, centered on a longitudinal axis, and a tubular side wall extending axially with respect to a periphery of the crown to an open end, said crown having at least a peripheral region integral with the side wall;

forming a mounting member having an upper member part and opposite thereto gudgeon pin bosses and a periphery dimensioned to fit within and interface with the tubular side wall;

disposing the mounting member within the tubular side wall such that the gudgeon pin bosses face the open end, the upper part interfaces with the crown at least a radially extending crown interface defining mutual axial location reference, and the periphery interfaces with the side wall at a wall interface spaced axially from the crown periphery and radially from said radially extending crown interface, defining thereby a transversely extending closure plate closing partly from below a peripheral chamber in the crown; and

permanently bonding the mounting member to the shell part at said wall interface and to the crown at a crown bonding interface radially inwardly of said wall interface;

wherein said crown includes a combustion bowl having a combustion bowl wall and defining a combustion bowl floor displaced axially of the crown peripheral region by said bowl wall by the mounting member, and wherein said permanently bonding step includes bonding the mounting member to the crown by way of said crown bonding interface between the combustion bowl floor defined by the mounting member and the combustion bowl wall defined by the crown; and

defining said crown bonding interface extending in a substantially axial direction accessible from outside of the combustion bowl and bonding the combustion bowl floor to the combustion bowl wall by access through the combustion bowl.

2. The method of claim 1 comprising bonding the mounting member to said crown and the tubular side wall at interfaces at a substantially same axial position.

3. The method of claim 1 comprising forming in the tubular side wall adjacent the crown a region of axially spaced circumferentially extending ring grooves and bonding the periphery of the mounting member to the side wall at an end of a ring groove region remote from the crown.

4. The method of claim 1 wherein the step of forming the tubular side wall and at least a peripheral region of the crown comprises bounding a central crown region, as an integral shell body and by forming at least pan of the central crown region as the combustion bowl having a bowl wall and a bowl floor displaced axially of the crown peripheral region by said bowl wall, and by bonding the mounting member to the crown at the combustion bowl.

5. The method of claim 4 comprising defining a radially extending the crown location interface between the mounting member and the crown, serving as a mutual axial location reference between a mounting member and the crown, at the junction between the combustion bowl wall and bowl floor.

6. The method according to claim 5 comprising defining said radially extending interface by an axial extension to the combustion bowl wall.

7. The method according to claim 4 wherein the step of bonding the mounting member to the crown at the radially extending crown location interface between the mounting member and the crown serves as a mutual axial location reference.

8. The method of claim 1 comprising bonding the combustion bowl floor to the combustion bowl wall metallurgically by applying heat from a source externally of the piston by access through the combustion bowl.

9. The method of claim 8 comprising bonding the interface by welding.

10. The method of claim 1 comprising defining the wall interface accessible from externally of the piston and bonding metallurgically by applying heat from a source externally of the piston.

11. The method of claim 10 comprising bonding the interface by welding.

12. The method of claim 1 comprising bonding the mounting member to the side wall substantially about a whole of its periphery.

13. The method of claim 1 comprising casting the mounting member.

14. The method of claim 1 comprising extruding the mounting member.

15. The method of claim 1 wherein the step of forming the outer shell part comprises the outer shell part flow forming about a rotating mandrel shaped to define an interior of the tubular side wall.

16. The method of claim 1 wherein the step of forming the outer shell part comprises back extruding the outer shell part about a mandrel shaped to define an interior of the tubular side wall.

17. The method of claim 16 comprising forming at least one valve pocket in the crown during the extrusion.

18. The method of claim 1 comprising forming a body shell and the mounting member from the same material.

19. The method of claim 1 comprising forming an outer shell part from steel.