Articulated piston skirt

1. A piston assembly comprising;

a piston head having a top extending radially from a first axis, said piston head including a first pin boss depending from said top and having a first pin bore,

said piston head including a second pin boss spaced from said first pin boss and depending from said top and having a second pin bore axially aligned with said first pin bore,

a connecting rod having a piston end,

said piston end of said connecting rod including a fork having a first connecting boss having a first connecting bore and having a second connecting boss spaced from said first connecting boss and having a second connecting bore axially aligned with said first connecting bore,

a piston skirt including a skirt wall extending along a curve disposed about said first axis for engaging a cylinder wall of an engine cylinder,

said piston skirt including a bridge extending from said skirt wall through said first axis,

said bridge having a skirt bore,

a wrist pin,

said bridge being disposed between said first and second connecting bosses and said first and second connecting bosses being disposed between said first and second pin bosses with said first and second pin bores axially aligned with said first and second connecting bores and with said skirt bore on a second axis, and

said wrist pin extending within said first and second pin bores and said first and second connecting bores and said skirt bore along said second axis to interconnect said piston head and said connecting rod and said piston skirt.

2. A piston assembly as set forth in claim 1 wherein said skirt wall defines a passage axially aligned with said first and second pin bores and with said first and second connecting bores and with said skirt bore for permitting passage of said wrist pin therethrough.

3. A piston assembly as set forth in claim 2 including at least one circlip surrounding said wrist pin to engage one of said first and second pin bosses for limiting axial movement of said wrist pin along said second axis.

4. A piston assembly as set forth in claim 3 wherein said first pin boss extends axially between a first inner edge and a first outer edge and second pin boss extends axially between a second inner edge and a second outer edge and wherein said wrist pin extends between said first outer edge of said first pin boss and said second outer edge of said second pin boss.

5. A piston assembly as set forth in claim 4 wherein said first pin bore extends through said first pin boss between said first inner edge and said first outer edge and second pin bore extend through said second pin boss between said second inner edge and said second outer edge and wherein a pair of said circlips surround said wrist pin to engage said first and second pin bosses.

6. A piston assembly as set forth in claim 3 wherein said first pin bore extends within said first pin boss axially from said first inner edge toward said first outer edge and terminates between said first inner and first outer edges to define a blind bore and wherein said circlip engages said second pin boss.

7. A piston assembly as set forth in claim 2 wherein said skirt wall defines a first axial height in the direction of said first axis and wherein said wrist pin has a cylindrical shape having a pin diameter and wherein said first axial height of said skirt wall is at least 2% greater than said pin diameter.

8. A piston assembly as set forth in claim 7 wherein said first axial height of said skirt wall is between 2-20% greater than said pin diameter.

9. A piston assembly as set forth in claim 2 wherein said skirt wall extends cylindrically about said first axis having a cylindrical shape for axial alignment with said piston head.

10. A piston assembly as set forth in claim 9 wherein said skirt wall includes a plurality of corrugations disposed circumferentially about said first axis and extending axially along said first axis between said upper and lower edges.

11. A piston assembly as set forth in claim 10 including groups of said corrugations spaced axially from each other and separated by at least one straight section.

12. A piston assembly as set forth in claim 10 wherein said corrugations extend axially continuously along said first axis between said upper and lower edges.

13. A piston assembly as set forth in claim 9 wherein said piston head has a top extending radially from a first axis to a circular periphery and defines a combustion bowl extending into said top and disposed about said first axis and radially inwardly from said circular periphery and wherein said piston head includes a ring belt depending downwardly from said circular periphery in a cylindrical shape and having a plurality of ring grooves extending into said ring belt for receiving a plurality of piston rings and being axially aligned with said skirt wall.

14. A piston assembly comprising;

a piston head having a top extending radially from a first axis to a circular periphery and having a combustion bowl extending into said top and disposed about said first axis and radially inwardly from said circular periphery,

said piston head including a ring belt depending downwardly from said circular periphery in a cylindrical shape and having a plurality of ring grooves extending into said ring belt for receiving a plurality of piston rings,

said piston head including a first pin boss depending downwardly from said top and spaced radially inwardly of said ring belt and having a first pin bore,

said piston head including a second pin boss spaced from said first pin boss and depending downwardly from said top and spaced radially inwardly of said ring belt and having a second pin bore axially aligned with said first pin bore,

said first pin boss extending in the direction of said first pin bore between a first inner edge and a first outer edge,

said second pin boss extending in the direction of said second pin bore between a second inner edge and a second outer edge,

a connecting rod extending between a piston end and a crank end,

said piston end of said connecting rod including a fork having a first connecting boss having a first connecting bore and having a second connecting boss spaced from said first connecting boss having a second connecting bore axially aligned with said first connecting bore,

a piston skirt including a skirt wall extending cylindrically about said first axis for axial alignment with said ring belt and extending axially along said first axis between an upper edge and a lower edge for engaging a cylinder wall of an engine cylinder,

said piston skirt including a bridge extending diametrically through said first axis,

said bridge having a skirt bore,

a wrist pin having a cylindrical shape having a wrist pin diameter,

said skirt wall having a passage axially aligned with said skirt bore for permitting passage of said wrist pin there through,

said skirt wall having a first axial height in the direction of said first axis of between 2-20% of said wrist pin diameter,

at least one circlip,

said bridge being disposed between said first and second connecting bosses and said first and second connecting bosses being disposed between said first and second pin bosses with said first and second pin bores axially aligned with said first and second connecting bores and with said skirt bore on a second axis,

said wrist pin extending within said first and second pin bores between said first outer edge of said first pin boss and said second outer edge of said second pin boss and through said first and second connecting bores and through said skirt bore along said second axis to interconnect said piston head and said connecting rod and said piston skirt,

said circlip surrounding said wrist pin to engage one of said first and second pin bosses for limiting axial movement of said wrist pin along said second axis, and

said skirt wall including a plurality of corrugations disposed circumferentially about said first axis and extending axially along said first axis between said upper and lower edges.

15. A piston assembly as set forth in claim 14 wherein said first pin bore extends through said first pin boss between said first inner edge and said first outer edge and second pin bore extends through said second pin boss between said second inner edge and said second outer edge and wherein a pair of said circlips surround said wrist pin to engage said first and second pin bosses.

16. A piston assembly as set forth in claim 14 wherein said first pin bore extends within said first pin boss axially from said first inner edge toward said first outer edge and terminates between said first inner and first outer edges to define a blind bore and wherein said circlip engages said second pin boss.