Variable vane assembly

• US 8,376,693 B2
• Filed: 10/30/2009
• Issued: 02/19/2013
• Est. Priority Date: 01/26/2009
• Status: Active Grant

• Current Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Original Assignee: Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Inventors: Gilman, Justin P., Eifert, Andrew J.
• Primary Examiner(s): EDGAR, RICHARD A
• Application Number:
  US12/588,880
• Publication Number:
  US 20100189549A1
• Time in Patent Office: 1,208 Days
• Field of Search: 415/159, 415/160, 415/152, 415/150, 415/148, 415/163, 415/164, 415/165, 415/166
• US Class Current: 415/160
• CPC Class Codes: F01D 17/162 for axial flow, i.e. the vanes turning around axes which are essentially perpendicular to the rotor centre line F01D17/167 takes precedence
• CPC Class Codes: F04D 29/563 specially adapted for elastic fluid pumps
• CPC Class Codes: F05D 2250/14 elliptical
• CPC Class Codes: F05D 2260/79 Bearing, support or actuation arrangements therefor
• CPC Class Codes: F05D 2300/501 Elasticity

Abstract

A variable vane assembly, for example of stator vanes in a gas turbine engine, comprises vanes which can be turned together about their longitudinal axes by means of a unison ring which is turned by an actuator about the engine axis. The unison ring is coupled to the vanes by levers. The unison ring has varying stiffness along its circumference, increasing in the direction away from the drive point at which the actuator acts. The varying stiffness may be achieved by varying the radial thickness of the unison ring. The unison ring is thus able to resist ovalization so that the vanes move together.

Claims

1. A variable vane assembly comprising:

a unison ring having a radial stiffness that varies in a circumferential direction thereof;

an array of variable vanes coupled to the unison ring for common displacement upon rotation of the unison ring about its central axis by means of a force applied at a first drive point and at a second drive point on the unison ring;

a first actuator that is;

i) configured to rotate the unison ring about its central axis, and ii) connected to the unison ring at the first drive point, the first drive point being positioned in a region of minimum stiffness on the unison ring; and

a second actuator that is;

i) configured to rotate the unison ring about its central axis, and ii) connected to the unison ring at the second drive point, the second drive point being positioned in a region that is diametrically opposite to the region of minimum stiffness.

2. The variable vane assembly as claimed in claim 1, wherein

the radial stiffness of the unison ring varies over at least 50% of a circumference of the unison ring.

3. The variable vane assembly as claimed in claim 1, wherein

the radial stiffness varies progressively with distance from the first drive point and the second drive point.

4. The variable vane assembly as claimed in claim 1, wherein

a radial dimension of a cross-section of the unison ring varies circumferentially to provide variation in the radial stiffness.

5. The variable vane assembly as claimed in claim 1, wherein

the unison ring comprises a first member having a uniform cross-section and a second reinforcing member providing variation in the radial stiffness.

6. The variable vane assembly as claimed in claim 5, wherein

the second reinforcing member has a cross-section which varies circumferentially.

7. A gas turbine engine comprising the variable vane assembly in accordance with claim 1.