The traditional internal combustion engine relies on connecting rods for transmitting combustion power from a piston main body a crankshaft of the engine, thereby converting the linear motion of the piston main body to rotational motion at the crankshaft. Combustion power is generated from the intermittent ignition of gasoline that is injected into the combustion chamber, which creates extreme temperatures and pressures that are applied to the connecting rod. Further, combustion cycles occur thousands of times per minute during engine operation. Therefore the connecting rods are preferably relatively light to minimize overall weight that is acted upon by the combustion pressure of the engine. In order to meet these extreme competing demands, compromises must generally be made in the selection of a material from which connecting rods of an engine are formed.
Connecting rods have been formed from two different materials to better meet competing requirements for strength and weight of the connecting rod. However, connecting rods formed from multiple materials are relatively expensive and complex to manufacture. For example, the forming of a connecting rod from multiple materials generally necessitates a variety of finishing operations after the materials are joined or bonded together, to ensure a smooth and stable bond between the materials that will be durable over the life of the engine. These finishing operations add more cost to the manufacturing process. Thus, while connecting rods employing two different materials may allow fewer compromises in balancing the weight of a connecting rod versus its overall strength, the cost of manufacturing these connecting rods is much greater than traditional single-material connecting rod designs.
Accordingly, there is a need in the art for a connecting rod employing at least two different materials that is nonetheless relatively cost-effective and simple to manufacture.