Patent ID: 7350620

Claim:
A silencer for attenuating sound waves produced in a fluid that circulates through a fluid conveying means, said silencer comprising an expansion chamber formed with an outer peripheral wall and first and second end walls, said first end wall being provided with an inlet opening into said expansion chamber, said second end wall being provided with an outlet opening allowing said fluid to exit from said expansion chamber, said expansion chamber being in fluid communication with said fluid conveying means and adapated to carry said sound waves therethrough; a sound wave dissipater comprising a sound absorbing tubular member longitudinally disposed within said expansion chamber and arranged to absorb sound waves traveling through said expansion chamber, and having a central longitudinal void therethrough, said sound absorbing tubular member comprising an inner cylindrical wall, an outer surrounding cylindrical wall spaced from said inner cylindrical wall, inner ends of said inner cylindrical and outer surrounding walls contacting said first end wall, and outer ends thereof being closed by an annular wall, to define an enclosure, and sound wave absorbing means disposed in said enclosure, at least one of said inner inner cylindrical wall, said outer surrounding wall and said annular wall being provided with perforations sized to attenuate high frequency sound waves, and to allow them to be at least partially absorbed by said sound wave absorbing means; a resonator operatively associated with said sound wave dissipater and disposed in said central longitudinal void, said resonator comprising a plurality of baffles fixed to said inner cylindrical walls, and mounted at an acute angle with respect to said inner cylindrical wall, each baffle being shaped as a sector of a substantially frustoconical shell, said baffles being longitudinally spaced relative to one another and being helicoidally distributed along said inner cylindrical wall, in a manner that they completely block to view an annular region within said resonator, said resonator being constructed and arranged to cause attenuation, and reflection of said sound waves back and forth towards said sound wave dissipater.