The present invention relates to an adapter which is to be attached to the inlet end of an intake manifold and connected to means for holding an air cleaner in communication with the manifold, for example, for use in trucks, the adapter being adapted for use in connecting to the intake manifold a pipe for returning the exhaust gas from the engine to the intake manifold.
The term "aluminum" as used herein and in the appended claims includes pure aluminum, commercial pure aluminum containing traces of impurities and aluminum alloys. The term "wrought aluminum" as used herein refers to aluminum articles formed by plastic working. Further the term "metallurgical joining" as used herein and in the appended claims includes welding, brazing and soldering.
To ensure complete combustion of exhaust gas and an increased efficiency, for example, in trucks, the exhaust gas is partly returned to the intake manifold and burned in the engine cylinder. Since the exhaust gas has a high temperature of about 350.degree. C., a pipe of stainless steel or carbon steel is used for returning the exhaust gas. Conventionally, stainless steel or carbon steel adapter is attached to the inlet end of the intake manifold and has connected thereto a throttle body constituting means for holding an air cleaner in communication with the manifold. The exhaust gas return pipe is brazed to the adapter.
However, the conventional adapter has the problem of being heavy and costly.
Accordingly, aluminum adapters are considered useful, whereas the exhaust gas return pipe of stainless steel or carbon steel is difficult to braze to the adapter. Moreover, a layer of intermetallic compound is formed in the brazed joint, which therefore becomes brittle and is liable to break owing to vibration.