Variable diffuser with axially translating end wall for a centrifugal compressor

Patent metadata

Field	Value
Publication number	US-10753370-B2
Application number	US-201715602643-A
Country	US
Kind code	B2
Filing date	May 23, 2017
Priority date	May 23, 2017
Publication date	Aug 25, 2020
Grant date	Aug 25, 2020

Abstract

A variable diffuser for a centrifugal compressor comprises a passage between opposing disc faces and a plurality of vanes extending therethrough with a fixed angle relative to the engine centerline. Axial displacement between the opposing disc faces is variable. The vanes extend through one of the opposing disc faces as that disc face is axially translated.

First claim

What is claimed is:

1. A variable diffuser for a centrifugal compressor comprising:
a first disc having a first disc face extending radially from a first inner edge to a first outer edge:
a second disc having a second disc face extending radially from a second inner edge to a second outer edge, the second disc positioned opposite and displaced from the first disc such that said second disc face opposes said first disc face, the second disc defining a plurality of pocketed vane slots spaced about a circumference of the second disc face;
a passage defined between the first disc face and the second disc face, wherein axial displacement between the first inner edge and the second inner edge defines an inlet of the passage and axial displacement between the first outer edge and the second outer edge defines an outlet of the passage;
a plurality of vanes within the passage, each vane spanning at least between the first disc face and the second disc face and having a fixed angle with respect to an axis of rotation of the centrifugal compressor, wherein each vane is translationally fixed to the first disc face and extends axially with at least a portion of the vane extending into a respective one of the plurality of pocketed vane slots; and
an actuator comprising a cam mechanism and a unison ring, the actuator coupled to one of the first disc and the second disc, wherein axial displacement between the first disc face and the second disc face is varied upon actuation of the actuator,
wherein each of the pocketed vane slots defines a pocket unique to a corresponding one of the plurality of vanes.

2. The variable diffuser of claim 1 , wherein the first disc face and the second disc face are co-axial.

3. The variable diffuser of claim 2 , wherein the first disc face and the second disc face are parallel.

4. The variable diffuser of claim 1 , wherein the actuator further comprises a piston coupled between one of the first disc and the second disc and the cam mechanism.

5. The variable diffuser of claim 4 , wherein the actuator comprises at least three pistons distributed circumferentially around one of the first disc and the second disc.

6. The variable diffuser of claim 4 , wherein the cam mechanism comprises a translationally fixed outer sleeve and a rotationally fixed inner sleeve; and
wherein the outer sleeve is rotationally driven by a crank arm and the piston is translationally driven by the inner sleeve.

7. The variable diffuser of claim 6 , wherein the inner sleeve is rotationally fixed to the piston via an axial key and keyway.

8. A centrifugal compressor comprising:
an impeller having a high pressure outlet;
a scroll; and
a variable diffuser positioned between the impeller and the scroll, wherein high pressure gas flows from the high pressure outlet through the variable diffuser to the scroll, the variable diffuser comprising:
a front disc having a front disc face extending radially from a front inner edge to a front outer edge;
a back disc having a back disc face extending radially from a back inner edge to a back outer edge, the back disc defining a plurality of pocketed vane slots spaced about a circumference of the back disc face:
a passage defined between the front disc face and the back disc face;
an inlet defined between the respective inner edges, the inlet in fluid communication with the high pressure outlet and an outlet defined between the respective outer edges, the outlet in fluid communication with the scroll;
a plurality of vanes within the passage, each vane spanning at least between the front disc face and the back disc face and having a fixed angle with respect to an axis of rotation of the centrifugal compressor each vane rigidly fixed to the front disc face and extending across the passage and having a least a portion of the vane extending into a respective one of the plurality of pocketed vane slots;
the back disc face having a first and second axial position with respect to the front disc face; and
an actuator operably connected to the back disc face and translating the back disc face between a first axial position and a second axial position, the actuator comprising: a piston connected to the back disc face, a cam mechanism, and a crank arm,
wherein each of the pocketed vane slots defines a pocket unique to a corresponding one of the plurality of vanes.

9. The centrifugal compressor of claim 8 , comprising at least three pistons distributed circumferentially around the back disc and wherein the cam mechanism comprises a translationally fixed outer sleeve and a rotationally fixed inner sleeve; wherein the outer sleeve is rotationally driven by the crank arm and the piston is translationally driven by the inner sleeve.

10. The centrifugal compressor of claim 9 , wherein the inner sleeve is rotationally fixed to the piston via an axial key and keyway.

11. A method of changing the operational range of a compressor comprising: defining a diffuser between two axially displaced and opposing faces, wherein one of said faces defines a plurality of pocketed vane slots; fixing a plurality of vanes at the outlet of the compressor, each vane spanning from one of said opposing faces and into a respective one of said plurality of pocketed vane slots to interact with fluid within the diffuser to convert dynamic energy of the fluid into static pressure; transitioning between a first arrangement and a second arrangement of the opposing faces as a function of flow rate of the compressor, wherein the axial displacement between the opposing faces is equal to or less than the span of each of the plurality of vanes in the first arrangement, and, in the second arrangement, the axial displacement between the opposing faces is less than in the first arrangement, wherein each of the pocketed vane slots defines a pocket unique to a corresponding one of the plurality of vanes.

12. The method of claim 11 , wherein the step of transitioning between the first arrangement and the second arrangement comprises translating axially one of the opposing faces with respect to the other.

Assignees

• Rolls Royce Corp

Inventors

• Hall Christopher
• Sayre David

Classifications

• F04D29/444

  Bladed diffusers · CPC title

• F04D27/0253

  by throttling (F04D27/0246 takes precedence) · CPC title

• F04D29/464 Primary

  adjusting flow cross-section, otherwise than by using adjustable stator blades · CPC title

• F04D29/462 Primary

  especially adapted for elastic fluid pumps · CPC title

• F04D27/002

  by varying geometry within the pumps, e.g. by adjusting vanes · CPC title