Piston with central directional oil flow and wrist pin lubrication feature and method of construction thereof

A piston, comprising:

• a piston body having a central axis along which said piston body reciprocates within a cylinder bore, said piston body having an upper crown portion having an upper combustion wall against which combustion forces directly act in the cylinder bore and at least one annular upper rib depending from the upper combustion wall to a free end, said piston body further including a lower crown portion having at least one annular lower rib extending to a free end fixed to said at least one annular upper rib, said lower crown portion having an inner gallery floor extending radially inwardly relative to said at least one annular lower rib and a pair of pin bosses depending generally from said inner gallery floor with a space provided between said pin bosses for receipt of a small end of a connecting rod;
• said upper crown portion having an upper post depending from said upper combustion wall along said central axis to a free end;
• said lower crown portion having a lower post extending upwardly from said inner gallery floor along said central axis to a free end, wherein a pocket extends axially into said free end of said upper post and said free end of said lower post extends axially into said pocket;
• and
• said free end of said upper post and said free end of said lower post forming a labyrinth passage.

A piston, comprising:

• a piston body having a central axis along which said piston body reciprocates within a cylinder bore, said piston body having an upper crown portion having an upper combustion wall against which combustion forces directly act in the cylinder bore and at least one annular upper rib depending from the upper combustion wall to a free end, said piston body further including a lower crown portion having at least one annular lower rib extending to a free end fixed to said at least one annular upper rib, said lower crown portion having an inner gallery floor extending radially inwardly relative to said at least one annular lower rib and a pair of pin bosses depending generally from said inner gallery floor with a space provided between said pin bosses for receipt of a small end of a connecting rod;
• said upper crown portion having an upper post depending from said upper combustion wall along said central axis to a free end;
• said lower crown portion having a lower post extending upwardly from said inner gallery floor along said central axis to a free end, wherein said free end of said lower post has a counterbore and said free end of said upper post extends axially into said counterbore, wherein said lower post has a first oil flow passage extending along said central axis beneath said counterbore, and wherein said lower post has a second oil flow passage extending transverse to said central axis, said second oil flow passage intersecting said first oil flow passage;
• and
• said free end of said upper post and said free end of said lower post forming a labyrinth passage.

A piston, comprising:

• a piston body having a central axis along which said piston body reciprocates within a cylinder bore, said piston body having an upper crown portion having an upper combustion wall against which combustion forces directly act in the cylinder bore and at least one annular upper rib depending from the upper combustion wall to a free end, said piston body further including a lower crown portion having at least one annular lower rib extending to a free end fixed to said at least one annular upper rib, said lower crown portion having an inner gallery floor extending radially inwardly relative to said at least one annular lower rib and a pair of pin bosses depending generally from said inner gallery floor with a space provided between said pin bosses for receipt of a small end of a connecting rod;
• said upper crown portion having an upper post depending from said upper combustion wall along said central axis to a free end;
• said lower crown portion having a lower post extending upwardly from said inner gallery floor along said central axis to a free end, wherein said lower post has a first oil flow passage extending along said central axis, and wherein said lower post has a second oil flow passage extending transverse to said central axis, said second oil flow passage intersecting said first oil flow passage;
• and
• said free end of said upper post and said free end of said lower post forming a labyrinth passage.

A method of constructing a piston, comprising:

• providing an upper crown portion having an upper combustion wall against which combustion forces directly act in the cylinder bore and at least one annular upper rib depending from the upper combustion wall to a free end with an upper post depending from the upper combustion wall along the central axis to a free end;
• providing a lower crown portion having at least one annular lower rib extending to a free end and an inner gallery floor extending radially inwardly relative to the at least one lower rib with a pair of pin bosses spaced for receipt of a small end of a connecting rod and having a lower post extending upwardly from the inner gallery floor along the central axis to a free end;
• and
• fixing the at least one upper rib of the upper crown portion to the at least one lower rib of the lower crown portion such that the upper post and the lower post are radially and entirely spaced from one another and the free end of the upper post and the free end of the lower post extend axially beyond one another and forming a labyrinth passage between the free end of the upper post and the free end of the lower post.

A method of constructing a piston, comprising:

• providing an upper crown portion having an upper combustion wall against which combustion forces directly act in the cylinder bore and at least one annular upper rib depending from the upper combustion wall to a free end with an upper post depending from the upper combustion wall along the central axis to a free end;
• providing a lower crown portion having at least one annular lower rib extending to a free end and an inner gallery floor extending radially inwardly relative to the at least one lower rib with a pair of pin bosses spaced for receipt of a small end of a connecting rod and having a lower post extending upwardly from the inner gallery floor along the central axis to a free end;
• fixing the at least one upper rib of the upper crown portion to the at least one lower rib of the lower crown portion and forming a labyrinth passage between the free end of the upper post and the free end of the lower post;
• and
• further including forming a pocket extending axially into the free end of the upper post and extending the free end of the lower post axially into the pocket.

A method of constructing a piston, comprising:

• providing an upper crown portion having an upper combustion wall against which combustion forces directly act in the cylinder bore and at least one annular upper rib depending from the upper combustion wall to a free end with an upper post depending from the upper combustion wall along the central axis to a free end;
• providing a lower crown portion having at least one annular lower rib extending to a free end and an inner gallery floor extending radially inwardly relative to the at least one lower rib with a air of s in bosses spaced for receipt of a small end of a connecting rod and having a lower post extending upwardly from the inner gallery floor along the central axis to a free end;
• fixing the at least one upper rib of the upper crown portion to the at least one lower rib of the lower crown portion and forming a labyrinth passage between the free end of the upper post and the free end of the lower post;
• forming a counterbore in the free end of the lower post and extending the free end of the upper post axially into the counterbore;
• forming a first oil flow passage extending along the central axis beneath said counterbore;
• and
• further including forming a second oil flow passage extending transverse to the central axis and intersecting the first oil flow passage with the second oil flow passage.

A method of constructing a piston, comprising:

• providing an upper crown portion having an upper combustion wall against which combustion forces directly act in the cylinder bore and at least one annular upper rib depending from the upper combustion wall to a free end with an upper post depending from the upper combustion wall along the central axis to a free end;
• providing a lower crown portion having at least one annular lower rib extending to a free end and an inner gallery floor extending radially inwardly relative to the at least one lower rib with a pair of pin bosses spaced for receipt of a small end of a connecting rod and having a lower post extending upwardly from the inner gallery floor along the central axis to a free end;
• fixing the at least one upper rib of the upper crown portion to the at least one lower rib of the lower crown portion and forming a labyrinth passage between the free end of the upper post and the free end of the lower post;
• forming a first oil flow passage extending along the central axis in the lower post;
• and
• further including forming a second oil flow passage extending transverse to the central axis and intersecting the first oil flow passage with the second oil flow passage.