PISTON WITH COMPLEX SHAPED COMBUSTION BOWL AND COOLING GALLERY AND METHOD OF CONSTRUCTION THEREOF
A piston and method of construction thereof is provided. The piston has a lower member with diametrically opposite skirt portions and axially aligned pin bores and an upper member joined to the lower member. The upper member has a substantially planar upper combustion surface and a combustion bowl depending from the upper combustion surface. An undercrown surface is formed directly opposite the combustion bowl and a combustion bowl rim transitions the combustion bowl with the upper combustion surface. At least one of the combustion bowl, the undercrown surface and the upper combustion surface has a machined surface and an “as forged” surface.
1 . A piston comprising:
a lower member, said lower member having diametrically opposite skirt portions and axially aligned pin bores;
an upper member joined to said lower member, said upper member having a substantially planar upper combustion surface and a combustion bowl depending from said upper combustion surface with an undercrown surface formed directly opposite said combustion bowl and a combustion bowl rim transitioning said combustion bowl with said upper combustion surface, at least one of said combustion bowl, said undercrown surface and said upper combustion surface having a machined surface and an “as forged” surface.
2 . The piston of claim 1 wherein at least one of said combustion bowl and said undercrown surface has a machined surface and an “as forged” surface.
3 . The piston of claim 2 wherein said machined surface is generally centrally located relative to a central longitudinal axis of the piston and said “as forged” surface extends annularly about said machined surface.
4 . The piston of claim 2 wherein said combustion bowl and said undercrown surface have a machined surface and an “as forged” surface.
5 . The piston of claim 4 wherein said upper combustion surface has a machined surface and an “as forged” surface.
6 . The piston of claim 1 wherein said upper combustion surface has a machined surface and an “as forged” surface.
7 . The piston of claim 1 wherein said combustion bowl, said undercrown surface, and said upper combustion surface have a machined surface and an “as forged” surface.
8 . The piston of claim 1 wherein said combustion bowl has a recess floor and a combustion bowl wall that converges at an angle of inclination relative to a central longitudinal axis along which the piston reciprocates from said upper combustion surface to said recess floor.
9 . The piston of claim 9 wherein said combustion bowl wall remains “as forged”.
10 . The piston of claim 9 wherein said combustion bowl wall extends at an angle of inclination relative to said central longitudinal axis between about 1-15 degrees.
11 . A method of constructing a piston, comprising:
forming a lower member having diametrically opposite skirt portions and axially aligned pin bores;
forging an upper member having a substantially planar upper combustion surface and a combustion bowl depending from said upper combustion surface with an undercrown surface formed directly opposite said combustion bowl and a combustion bowl rim transitioning said combustion bowl with said upper combustion surface;
joining said lower member to said upper member; and
machining a portion of at least one of said upper combustion surface, said combustion bowl and said undercrown surface, and leaving a portion of at least one of said upper combustion surface, said combustion bowl and said undercrown surface “as forged”.
12 . The method of claim 11 further including machining of portion of said combustion bowl and said undercrown surface and leaving a portion of said combustion bowl and said undercrown surface “as forged”.
13 . The method of claim 12 further including machining a portion of said combustion bowl and said undercrown surface that is generally centrally located relative to a central longitudinal axis of the piston leaving a portion of said combustion bowl and said undercrown surface “as forged” that extends annularly about the machined surfaces.
14 . The method of claim 11 further including machining a portion of said upper combustion surface and leaving a portion of said upper combustion surface “as forged”.
15 . The method of claim 11 further including machining a portion of said combustion bowl, said undercrown surface, and said upper combustion surface and leaving a portion of said combustion bowl, said undercrown surface and said upper combustion surface “as forged”.
16 . The method of claim 11 further including forging the combustion bowl having a recess floor and a combustion bowl wall that converges at an angle of inclination relative to a central longitudinal axis along which the piston reciprocates from the upper combustion surface to the recess floor.
17 . The method of claim 16 further including leaving the combustion bowl wall “as forged”.
18 . The method of claim 17 further including forging the combustion bowl wall having an angle of inclination relative to the central longitudinal axis between about 1-15 degrees.