Patent Application
20070283917
Embodiments of the invention are described in detail below on the basis of the enclosed drawing. The drawing shows schematically, and not true to scale, in:
In the area of the boss connections 16, an all-round flange 19 projecting radially outwards is provided. The combustion bowl 15 is limited by an all-round annular shoulder 21. The shoulder 21 has a lateral surface 22 parallel to the longitudinal axis A of the piston 10 and an end face 23 at right angles to it.
The ring carrier element 12 has an all-round and substantially cylindrical ring element 24 with an inner wall 32 which is provided in a manner known per se on its lateral surface with a top land 25 and a ring belt 26 with several annular grooves 27 for receiving piston rings, not shown. The lower free end of the ring element 24 forms a contact surface 28 resting on the flange 19 of the basic element 11.
The ring element 24 has in the area of the shoulder 21 of the basic element 11 an all-round edge 29 extending radially inwards of which the surface forms the outer annular area 31 of the piston crown 14, which surrounds the central area 13 of the piston crown 14 formed by the basic element 11. The ring element 24 and the edge 29 enclose the lateral surface 22 or the end face 23 of the shoulder 21 of the basic element 11 and are so dimensioned that a press fit of the ring carrier element 12 on the basic element 11 is constituted. For assembly, the metallic ring carrier element 12 is therefore heated and mounted on the basic element 11 in the manner shown in
As an additional safeguard, a weld 33 can also be provided between the edge 29 of the ring carrier element 12 and the end face 23 of the shoulder 21 of the basic element 11, as shown by example in
The inner wall 32 of the ring element 24 and an all-round recess 34 provided underneath the combustion bowl 15 in the basic element 11 form a cooling channel 35. Thanks to the slender design of the ring carrier element 12, the cooling channel 35 has a particularly large volume and extends from the shoulder 21 to the flange 19 of the basic element 11.
The ring carrier element 112 has a piston crown 114 provided in a manner known per se with a combustion bowl 115. The piston crown 114 is limited by an all-round and substantially cylindrical ring element 124 with an inner wall 132. The ring element 124 is provided on its lateral surface in a manner known per se with a top land 125 and a ring belt 126 with several annular grooves 127 for receiving piston rings, not shown. The lower free end of the ring element 124 forms a contact surface 128 resting on the flange 119 of the basic element 111.
The ring carrier element 112 has underneath the combustion bowl an annular contact surface 137 facing the basic element 111 and provided in some areas with a recess 138. The basic element 111 has accordingly a support plate 139 facing the ring carrier element 112 and provided with an annular support surface 141 corresponding to the contact surface 137. The support surface 141 has in some areas a raised area 142 corresponding to the recess 138.
In the assembled state, the inner wall 132 of the ring element 124 encloses the annular collar 136 of the basic element 111, and the raised area 142 of the basic element 111 engages in the recess 138 of the ring carrier element 112, as shown in
For assembly, the metallic ring carrier element 112 is therefore heated and mounted on the basic element 111 in the manner shown in
The inner wall 132 of the ring element 124, the collar 136, an all-round recess 134 provided underneath the combustion bowl 115 in the ring carrier element 112 and the support plate 139 form a cooling channel 135. Thanks to the slender design of the ring carrier element 112, the cooling channel 135 has a particularly large volume and extends from the underside of the piston crown 114 to the flange 119 of the basic element 111.
