STEEL PISTON WITH COOLING GALLERY AND METHOD OF CONSTRUCTION THEREOF

• US 20120037112A1
• Filed: 05/20/2011
• Published: 02/16/2012
• Est. Priority Date: 11/06/2009
• Status: Active Grant

• Current Assignee: Tenneco Incorporated (Apollo Global Management, Inc.)
• Original Assignee: Tenneco Incorporated (Apollo Global Management, Inc.)
• Inventors: Muscas, Florin
• Granted Patent: US 9,970,384 B2
• Time in Patent Office: Days
• US Class Current: 123/193.6
• 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 2003/0061 by welding
• CPC Class Codes: F02F 3/003 the parts being connected by casting, brazing, welding or clamping
• CPC Class Codes: F02F 3/22 the fluid being liquid
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

A piston and method of construction is provided. The piston includes a top part fixed to a bottom part. The top part has an uppermost surface with annular inner and outer upper joining surfaces depending therefrom. The bottom part has a pair of pin bosses with pin bores aligned with one another along a pin bore axis; a pair of upwardly extending annular inner and outer lower joining surfaces and a combustion bowl wall. Inner and outer weld joints fix the inner and outer upper and lower joining surfaces to one another. An annular cooling gallery is formed laterally between the upper and lower joining surfaces. The inner weld joint joining the top part to the bottom part is located within the combustion bowl wall and configured to minimized the compression height of the piston.

Claims

1. A piston for an internal combustion engine, comprising:

an upper piston part;

a lowerpiston part;

at least said lower piston part being fabricated from a ferrous based material;

said lower piston part having a pair of pin bosses formed with associated pin bores aligned along a pin bores axis;

said lower piston further including a pair of piston skirt portions that are formed of one piece with said pin bosses of the same material;

said upper and lower piston parts each including an outer annular wall and an inner annular wall spaced radially apart from one another and presenting a channel portion between each of said inner and outer walls;

said inner and outer walls of said upper piston part being permanently joined across inner and outer weld joints to said respective inner and outer walls of said lower piston part to define therebetween an annular cooling gallery that has two side walls provided by the joined together inner and outer walls, an annular top wall formed by the upper piston part and a lower wall formed by the lower piston part;

said joined together upper and lower piston parts including a combustion bowl defined in part by an inner surface of said joined together inner walls, and further including a generally dome-shaped bottom wall of said combustion bowl extending radially inwardly of said inner wall of said lower piston part;

said inner weld joint being exposed to said combustion bowl;

said joined together piston parts including a piston height dimension, PH, measured from a bottom edge of said pin boss to a top face of said upper wall;

said joined together piston parts including a compression height dimension, CH, measured from said pin bore axis to said top face of said upper wall;

said joined together piston parts including a piston diameter, PD, measured as the outer diameter of the upper wall; and

wherein D equals about 103 mm, CH equals about 40 mm and the ratio of CH/PH equals about ⅔

.

2. The piston of claim 1 wherein said upper and lower piston parts are fabricated of steel.

3. The piston of claim 1 wherein said weld joints are friction weld joints.

4. The piston of claim 1 wherein an outer surface of said outer walls of said upper and lower piston parts are formed with a plurality of ring grooves, and said cooling gallery extends both above and below said plurality of ring grooves.

5. The piston of claim 1 wherein said inner weld joint is spaced above said outer weld joint.

6. The piston of claim 1 wherein said joined together upper and lower piston parts include a central longitudinal piston axis an said pin bores include a longitudinal pin axis that is parallel to but laterally offset from said piston axis.

7. The piston of claim 6 wherein said offset is about 0.5 mm.

8. The piston of claim 1 wherein said pin bores are coated with manganese phosphate and are free of insert bearings or bushings.

9. The piston of claim 8 wherein said skirt portions are coated with graphite.

10. The piston of claim 1 wherein said pin bosses have inner face surfaces that are substantially planar along their length and diverge away from one another at a fixed single angle from top to bottom when view in cross section.

11. The piston of claim 10 wherein the space between said pin bosses extends above the bottom wall of said gallery and above a lowest region of said combustion bowl.

17. The piston of claim 1 including a pair of openings in said bottom wall to provide open passages into said cooling gallery for the introduction and removal of cooling oil into and out of said cooling gallery.

12. The piston of claim I wherein a lower and radially innermost corner of said cooling gallery extends radially inwardly beyond a radially outermost region of said combustion bowl.

13. The piston of claim 12 wherein said lower corner of said cooling gallery extends radially inward beyond an upper and radially inner most corner of said cooling gallery.

14. The piston of claim 13 wherein said radially outer most region of said combustion bowl lies radially between said lower and upper corners of said cooling gallery.

15. The piston of claim 14 wherein said inner weld joint lies between said upper and lower corners of said cooling gallery.

16. The piston of claim 15 wherein said outer weld joint lies below said inner weld joint.

18. A piston for an internal combustion engine, comprising:

an upper piston part having radially spaced inner and outer joining surfaces;

a lower piston part with radially spaced joining surfaces and fabricated of ferrous based material;

inner and outer weld joints permanently joining said inner and said outer joining surfaces of said upper and said lower piston parts, respectively, and defining a cooling gallery therebetween and a combustion bowl inward of said cooling gallery and open to a top of the piston;

said inner weld joint extending between said cooling gallery and said combustion bowl;

said lower piston part including a pair of pin bosses and associated pin bores aligned along a common pin bore axis, and a pair a skirt portion formed as one piece with said pin bosses of the same material;

said piston having a top face with an outer piston diameter, PD, and a compression height, CH, measured as the distance from said pin bore axis and said top face of said piston; and

wherein CH is between 38% to 45% of PD.