Piston for an internal combustion engine

Abstract

A piston for an internal combustion engine, has a lower piston part and an upper piston part disposed on the lower piston part. The upper piston part has a top land that runs around its circumference, and a ring belt that runs around its circumference. At least the upper piston part consists of a sintered material.

1 .- 21 . (canceled) 
     
     
         22 . A piston, comprising:
 a lower piston part having radially inner and radially outer joining surfaces; and   an upper piston part having radially inner and radially outer joining surfaces, the upper piston part inner and outer joining surfaces connected to the inner and outer joining surfaces of the lower piston part, respectively, wherein the lower piston part and the upper piston part cooperate to enclose an outer circumferential cooling channel disposed radially between the inner joining surfaces and radially between the outer joining surfaces, the upper piston part having a top land extending around its circumference; wherein the upper and lower piston parts cooperate to define a combustion bowl, and the inner joining surfaces of the upper and lower piston parts meet in the combustion bowl;   wherein the lower and upper piston parts are joined solely by the connection along the inner and outer joining surfaces.   
     
     
         23 . The piston according to  claim 22 , wherein the upper piston part defines a radially outer portion of the combustion bowl, and the lower piston part defines a radially inner portion of the combustion bowl. 
     
     
         24 . The piston according to  claim 22 , wherein the outer circumferential cooling channel is defined in part by a circumferential recess in the lower piston part. 
     
     
         25 . The piston according to  claim 22 , wherein the inner joining surfaces of the lower and upper piston parts are spaced away from the outer joining surfaces of the lower and upper piston parts in a vertical direction with respect to the piston. 
     
     
         26 . The piston according to  claim 22 , wherein the combustion bowl defines a centrally positioned region spaced away from the inner joining surfaces of the lower and upper piston parts in a vertical direction with respect to the piston. 
     
     
         27 . The piston according to  claim 22 , wherein the lower piston part includes one of a forged and a cast material. 
     
     
         28 . The piston according to  claim 22 , wherein the upper piston part is formed of a different material than the lower piston part. 
     
     
         29 . The piston according to  claim 28 , wherein the lower piston part is formed of a steel material. 
     
     
         30 . The piston according to  claim 22 , wherein the lower piston part is formed of a steel material. 
     
     
         31 . The piston according to  claim 22 , wherein at least the upper piston part includes a sintered material. 
     
     
         32 . The piston according to  claim 31 , wherein the lower piston part and the upper piston part are connected with one another by a solder material, and wherein the sintered material is infiltrated by the solder material. 
     
     
         33 . The piston according to  claim 22 , wherein the lower piston part and the upper piston part are joined together with one another by a solder material disposed in a region of the joining surfaces. 
     
     
         34 . The piston according to  claim 22 , wherein the upper part defines a ring groove extending around the circumference of the upper part. 
     
     
         35 . A piston, comprising:
 a lower piston part having radially inner and radially outer joining surfaces; and   an upper piston part having radially inner and radially outer joining surfaces, the upper piston part inner and outer joining surfaces connected to the inner and outer joining surfaces of the lower piston part, respectively, wherein the lower piston part and the upper piston part cooperate to enclose an outer circumferential cooling channel disposed radially between the inner joining surfaces and radially between the outer joining surfaces, the upper piston part having a top land extending around its circumference; wherein the upper and lower piston parts cooperate to define a combustion bowl, and the inner joining surfaces of the upper and lower piston parts meet in the combustion bowl such that the upper piston part defines a radially outer portion of the combustion bowl, and the lower piston part defines a radially inner portion of the combustion bowl;   wherein the lower and upper piston parts are joined solely by the connection along the inner and outer joining surfaces.   
     
     
         36 . The piston according to  claim 35 , wherein the inner joining surfaces of the lower and upper piston parts are spaced away from the outer joining surfaces of the lower and upper piston parts in a vertical direction with respect to the piston. 
     
     
         37 . The piston according to  claim 35 , wherein the combustion bowl defines a centrally positioned region spaced away from the inner joining surfaces of the lower and upper piston parts in a vertical direction with respect to the piston. 
     
     
         38 . The piston according to  claim 35 , wherein the lower piston part includes one of a forged and a cast material. 
     
     
         39 . The piston according to  claim 35 , wherein the upper piston part is formed of a different material than the lower piston part. 
     
     
         40 . The piston according to  claim 35 , wherein the lower piston part is formed of a steel material. 
     
     
         41 . The piston according to  claim 35 , wherein the lower piston part and the upper piston part are joined together with one another by a solder material disposed in a region of the joining surfaces.