Compression device and supercharger

1. A compression device comprising a centrifugal compressor and a silencer, the centrifugal compressor comprising:

an impeller for compressing a fluid;

an inlet guide, housing the impeller, for guiding the fluid; and

a scroll casing forming a scroll chamber for guiding the fluid which has passed through the inlet guide to outside, the scroll casing consisting of a single member;

wherein the silencer comprises a silencer assembly bolt penetrating through the silencer in a direction along a rotational axis of the impeller and fastening the silencer to the scroll casing,

wherein the silencer comprises: a first side wall extending in a direction intersecting with the rotational axis of the impeller; and an annular second side wall provided between the first side wall and the centrifugal compressor and surrounding the rotational axis, wherein an ambient-air introduction space for guiding an ambient air to the inlet guide is formed between the first side wall and the second side wall,

wherein the silencer assembly bolt extends from the first side wall to the scroll casing in a direction along the rotational axis of the impeller and fastens the first side wall, the second side wall, and the scroll casing,

wherein the silencer further comprises at least one silencer element provided in the ambient-air introduction space,

wherein the silencer element is supported, in the ambient-air introduction space, by the silencer assembly bolt,

wherein the scroll casing comprises a scroll chamber-forming portion forming the scroll chamber, and an annular outer projection projecting from the scroll chamber-forming portion toward the silencer, and

wherein the silencer assembly bolt fastens the silencer and the outer projection in a state where the second side wall abuts the outer projection.

2. The compression device according to claim 1 ,

wherein the at least one silencer element comprises a plurality of silencer elements arranged along the rotational axis, and

wherein each of the plurality of silencer elements is an annular element provided around the rotational axis and has an insert hole into which the silencer assembly bolt is inserted, and the silencer element is supported, in the ambient-air introduction space, by the silencer assembly bolt inserted into the insert hole.

3. The compression device according to claim 1 ,

wherein the centrifugal compressor further comprises a compressor assembly bolt fastening an inlet side of the inlet guide to the scroll casing,

wherein the scroll casing comprises an annular inner projection projecting from the scroll chamber-forming portion toward the silencer, the inner projection being disposed more inwardly than the outer projection in a radial direction of the impeller, and

wherein the compressor assembly bolt fastens the inlet side of the inlet guide and the inner projection.

4. The compression device according to claim 3 ,

wherein the outer projection projects further than the inner projection toward the silencer, and

wherein a gap is provided between the inlet guide and the silencer so that a space formed between the inner projection and the outer projection communicates with a space inside the inlet guide.

5. The compression device according to claim 1 ,

wherein the silencer assembly bolt is screwed into a bolt hole formed in the scroll casing.

6. The compression device according to claim 1 which is configured so that, even when the impeller breaks apart and an impeller fragment hits the inlet guide, a shock of hitting does not propagate directly from the inlet guide to the silencer assembly bolt, but propagates from the inlet guide to the silencer assembly bolt via the scroll casing.

7. The compression device according to claim 1 , wherein the silencer is not in contact with the inlet guide.

8. The compression device according to claim 1 , wherein the centrifugal compressor further comprises:

a diffuser member fitted to an outer peripheral portion of the inlet guide at an outlet side of the inlet guide and forming a diffuser passage connecting an interior of the inlet guide to the scroll chamber; and

a bolt fastening the diffuser member and the scroll casing.

9. A supercharger comprising the compression device according to claim 1 and a turbine configured to rotate with the centrifugal compressor of the compression device.