Crank shaft support assembly

A crank shaft support assembly for increasing stiffness and reducing thermal mismatch distortion in a crank shaft bore of an engine comprising different metals, the assembly comprising:

• a cylinder block comprising a first material;
• at least two crank journal inserts that are insert-molded into respective crank journal regions of the cylinder block, that comprise a second material having greater stiffness and a lower thermal coefficient of expansion than the first material, and that are shaped to provide a cross-planar mechanical lock between each crank journal insert and the cylinder block, the shape of each crank journal insert including one or more features selected from the group of features consisting of cross-planar ribbing, undercuts, and through-holes;
• at least two bearing caps bolted to the respective crank journal inserts and defining, along with the crank journal inserts, at least two crank shaft support rings defining a crank shaft bore coaxially aligned with a crank shaft axis;
• and
• each of the bearing caps comprises a material having higher stiffness and a lower thermal coefficient of expansion than the first material and is supported on the respective crank journal inserts independently of any direct connection to the cylinder block;
• and
• each crank journal insert being integrally formed as a single unitary piece along with at least one casting locator pin extending integrally from a lower surface of each insert.

A method for making a crank shaft support assembly, the method including the steps of:

• providing a first material and a second material having greater stiffness and a lower thermal coefficient of expansion than the first material;
• forming a crank journal insert comprising the second material and to include at least one casting locator pin extending integrally from a lower surface;
• supporting the crank journal insert in a crank journal region of a cylinder block core mold by holding the insert by the locator pin;
• casting a cylinder block by providing the first material in molten form in the cylinder block core mold and around the crank journal insert and allowing the first material to harden;
• forming a bearing cap comprising a material having greater stiffness and a lower thermal coefficient of expansion that the first material;
• and
• forming a crank shaft support ring by supporting the bearing cap on the crank journal insert.