Patent ID: 7988427

Claim:
A compressor comprising: a first rotor ( 26 ) having a first rotational axis ( 500 ); a second rotor ( 28 ; 30 ) having a second rotational axis ( 502 ; 504 ) and enmeshed with the first rotor; a discharge plenum ( 42 ); and a muffler system ( 200 ) comprising: a case ( 202 ); a sound-absorbing first element ( 232 ); a sound-absorbing second element ( 236 ) at least partially surrounding the first element and defining a generally annular flow path portion ( 230 ) between the first element and second element; a wall ( 250 ) at least partially surrounding the second element; and a sound-absorbing third element ( 261 ) at least partially surrounding the wall within the case, the wall abutting the second element and third element and each of the first ( 232 ), second ( 236 ), and third ( 261 ) elements comprising a plurality of rings ( 234 ; 238 , 240 , 242 ; 262 , 264 , 266 ) of porous expanded polypropylene.