This invention relates to internal combustion engines, and more particularly to plastic housings for such engines.
Small internal combustion engines--such as those used with lawnmowers, snowblowers, generators and the like--typically have a number of distinct components or housings for key parts of the engine. For example, the fuel tank is typically a separate component from the air filter housing. Similarly, the blower housing--which includes the air passageway through which forced air passes to cool the engine--is typically a separate component.
Each of these distinct components must be separately manufactured and assembled, greatly increasing the cost of the completed engine. Moreover, additional parts are typically required when these housings are distinct units. For example, a fuel line is needed between the fuel tank and the carburetor. Also, a flexible hose is often used between the air filter outlet and the air intake of the carburetor or other air/fuel mixing device. The use of these additional components also increases the cost in manufacturing and assembling the completed engine.
Since internal combustion engines by their very nature generate a great deal of heat, it has often been necessary to manufacture many of the engine components, such as the fuel tank, from metal materials due to the metal's ability to withstand the high temperatures generated by the engine. Since metal is expensive and requires a number of separate forming, punching and machining steps, the use of metal materials also increases the cost in manufacturing and assembling the component parts.