Patent ID: 8403635

Claim:
A diffuser apparatus which has a diffuser formed by a shroud side wall portion and a hub side wall portion opposite each other and provided as a passage space communicated with an exit side of an impellor radially outwardly of the impellor of a centrifugal compressor, the apparatus comprising: a hollow disc-like rotational member, a housing member which houses the rotational member therein so as to be rotatable about a rotational axis of the impellor and forms either one wall portion of the shroud side wall portion and the hub side wall portion, and a driving device for rotating the rotational member, wherein a side surface of the rotational member on a diffuser side is provided with a plate-like vane member having one end in a circumferential direction fixed to the rotational member, an other end in the circumferential direction movable in a direction of the rotational axis, and being flexible, the housing member is provided with an inclination path which has one end opened to a portion which forms the one wall portion, and bendably guides the vane member so that the other end in the circumferential direction of the vane member is moved in the circumferential direction with the rotation of the rotational member and is moved in the direction of the rotational axis so as to be projected into the diffuser, and the driving device rotates the rotational member so that the vane member is driven between a projected position where the other end in the circumferential direction of the vane member is projected into the diffuser and a retracted position where the other end in the circumferential direction of the vane member is retracted into the one wall portion.