Centrifugal compressor and refrigeration apparatus

Patent metadata

Field	Value
Publication number	US-2025020130-A1
Application number	US-202418900936-A
Country	US
Kind code	A1
Filing date	Sep 30, 2024
Priority date	Mar 30, 2022
Publication date	Jan 16, 2025
Grant date	—

Abstract

A casing of a centrifugal compressor has a first wall facing a back surface of an impeller. A back gap is formed between the back surface of the impeller and the first wall. A specific speed of the impeller is set to be less than 0.1. A ratio of an axial width s of the back gap to an impeller radius r satisfies a relationship of 0.008≤s/r≤0.5, where the axial width s is a width of the back gap in an axial direction of the shaft, and the impeller radius r is a radius of the impeller.

First claim

1 . A centrifugal compressor comprising:
a casing; an impeller housed in the casing; and a shaft coupled to the impeller, the casing having a wall facing a back surface of the impeller, the shaft being inserted into an insertion hole formed in the wall, a back gap being formed between the back surface of the impeller and the wall, wherein a specific speed of the impeller is set to be less than 0.1, and a ratio of an axial width s of the back gap to an impeller radius r satisfies a relationship of 0.008≤s/r≤0.5, where the axial width s is a width of the back gap in an axial direction of the shaft, and the impeller radius r is a radius of the impeller.

2 . The centrifugal compressor of claim 1 , wherein
the back gap includes a first gap corresponding to an inner peripheral side of the back surface of the impeller, the first gap forming a seal that seals between the back surface ( 91 ) of the impeller and the wall, and the back gap includes a second gap corresponding to an outer peripheral side of the back surface of the impeller, and the axial width s of the second gap is greater than the axial width s of the first gap and satisfies the relationship of the ratio (s/r) to the impeller radius r.

3 . The centrifugal compressor of claim 2 , wherein
the first gap extends in a direction perpendicular to an axis (X) of the shaft so as to be flat.

4 . The centrifugal compressor of claim 1 , further comprising:
a radial bearing supporting the shaft at an outer periphery of the shaft, wherein the radial bearing is a foil bearing or a magnetic bearing.

5 . The centrifugal compressor of claim 1 , wherein
a maximum number of rotations of the shaft is 30000 rpm or more.

6 . The centrifugal compressor of claim 1 , wherein
the impeller pumps a refrigerant, and the refrigerant is an HFC refrigerant, an HFO refrigerant, a natural refrigerant, or a refrigerant mixture thereof.

7 . A refrigeration apparatus comprising: a refrigerant circuit configured to perform a refrigeration cycle,
the refrigerant circuit including the centrifugal compressor of claim 1 .

8 . The centrifugal compressor of claim 2 , further comprising:
a radial bearing supporting the shaft at an outer periphery of the shaft, wherein the radial bearing is a foil bearing or a magnetic bearing.

9 . The centrifugal compressor of claim 3 , further comprising:
a radial bearing supporting the shaft at an outer periphery of the shaft, wherein the radial bearing is a foil bearing or a magnetic bearing.

10 . The centrifugal compressor of claim 2 , wherein
a maximum number of rotations of the shaft is 30000 rpm or more.

11 . The centrifugal compressor of claim 3 , wherein
a maximum number of rotations of the shaft is 30000 rpm or more.

12 . The centrifugal compressor of claim 4 , wherein
a maximum number of rotations of the shaft is 30000 rpm or more.

13 . The centrifugal compressor of claim 8 , wherein
a maximum number of rotations of the shaft is 30000 rpm or more.

14 . The centrifugal compressor of claim 9 , wherein
a maximum number of rotations of the shaft is 30000 rpm or more.

15 . The centrifugal compressor of claim 2 , wherein
the impeller pumps a refrigerant, and the refrigerant is an HFC refrigerant, an HFO refrigerant, a natural refrigerant, or a refrigerant mixture thereof.

16 . The centrifugal compressor of claim 3 , wherein
the impeller pumps a refrigerant, and the refrigerant is an HFC refrigerant, an HFO refrigerant, a natural refrigerant, or a refrigerant mixture thereof.

17 . The centrifugal compressor of claim 4 , wherein
the impeller pumps a refrigerant, and the refrigerant is an HFC refrigerant, an HFO refrigerant, a natural refrigerant, or a refrigerant mixture thereof.

18 . The centrifugal compressor of claim 5 , wherein
the impeller pumps a refrigerant, and the refrigerant is an HFC refrigerant, an HFO refrigerant, a natural refrigerant, or a refrigerant mixture thereof.

19 . The centrifugal compressor of claim 8 , wherein
the impeller pumps a refrigerant, and the refrigerant is an HFC refrigerant, an HFO refrigerant, a natural refrigerant, or a refrigerant mixture thereof.

20 . The centrifugal compressor of claim 9 , wherein
the impeller pumps a refrigerant, and the refrigerant is an HFC refrigerant, an HFO refrigerant, a natural refrigerant, or a refrigerant mixture thereof.

Assignees

• Daikin Ind Ltd

Inventors

• Iwata Arihiro
• Nishimura Kosuke
• Tanaka Koichi
• Fukuda Daigo
• KAWACHIYA Yuki

Classifications

• F04D29/4206

  especially adapted for elastic fluid pumps · CPC title

• F04D29/102

  especially adapted for elastic fluid pumps · CPC title

• F04D29/056

  Bearings · CPC title

• F04D29/051

  Axial thrust balancing · CPC title

• F25B1/053

  of turbine type · CPC title