| 摘要 |
<p>A pneumatic sound generator, such as an automobile horn, comprises a generally cup-shaped housing spanned by a membrane that rests against a central tubular boss forming a seat for the mouthpiece of a cornet through which air admitted into the housing via a lateral inlet escapes as the oscillating membrane is lifted off the boss. The cornet abuts an inner annular shoulder of the boss, together with a tubular insert which is either thermoplastic, received between the metallic cornet and housing, or metallic, seated within the mouthpiece of the thermoplastic cornet. In either case, the thermoplastic part-which preferably has a polygonal or corrugated inner cross-section-is tightly squeezed between two metallic members forcing an annular bead thereof into a surrounding groove of the inner periphery of the boss to form therewith an airtight seal.</p> |
