Variable pitch rate means

• US 3,876,334 A
• Filed: 04/08/1974
• Issued: 04/08/1975
• Est. Priority Date: 04/08/1974
• Status: Expired due to Term

• Current Assignee: Merritt B. Andrews
• Original Assignee: Merritt B. Andrews
• Inventors: Andrews, Merritt B.
• Primary Examiner(s): Powell, Jr., Everette A.
• Application Number:
  US05/459,244
• Time in Patent Office: 365 Days
• Field of Search: 416/160,147,108,109,112 415/152,163
• US Class Current: 416/160
• CPC Class Codes: F01D 7/00 Rotors with blades adjustable in operation; Control thereof for reversing F01D1/30
• CPC Class Codes: F04D 29/323 adjustable
• CPC Class Codes: F04D 29/36 adjustable flexible blades F04D29/382
• CPC Class Codes: F05D 2220/36 specially adapted for the fan of turbofan engines
• CPC Class Codes: F05D 2260/74 by turning around an axis perpendicular the rotor centre line
• CPC Class Codes: F05D 2260/76 the adjusting mechanism using auxiliary power sources

Abstract

The pitch velocity of alternate and individual high solidity variable pitch blades of a bypass fan propulsor vary so as to pass through zero or flat pitch at different intervals, although ending at the same pitch at the extent of their travel.

Claims

1. Pitch change means for a propulsor having a plurality of blades circumferentially supported in a rotatable hub and means, including a pitch change actuator, for varying the pitch thereof, and additional means for varying the rate of change of alternate of said blades and means for imparting motion to said actuator.

2. Pitch change means as defined as in claim 1 wherein said pitch change actuator is rotational.

3. Pitch change means as claimed in claim 1 wherein the blades have a solidity factor of one or greater.

4. In a propulsor for aircraft having a turbine type of power plant driving a variable pitch fan mounted in a power plant bypass duct, a hub supporting a plurality of fan blades that are so dimensioned that adjacent blades when in a given plane overlap each other, means for varying the rate of change of each and alternate blades so that adjacent blades pass through the plane where interference occurs at different intervals.

5. Pitch change actuating means for a bariable pitch propulsor having a hub supporting a plurality of circumerentially mounted blades for pitch change movement, said means including a ring-like gear having a nonuniform surface, a noncircular gear operatively connected to each of said blades mating with teeth formed in said nonuniform surface such that alternate nonuniform gears are spaced equidistant from a plane taken transverse through the axis of rotation of said ring-like gear and the center of rotation of said noncircular gears, means for imparting rotary motion to said ring-like gear for effectuating pitch change whereby the pitch rate of alternate blades will vary.

6. Pitch change actuating means as claimed in claim 5 wherein said noncircular gear is segmented.

7. Pitch change actuating means as claimed in claim 5 wherein said nonuniform surface takes a sinusoidal shape.

8. Pitch change actuating means as claimed in claim 5 wherein said blades have solidity greater than one.