Pitch change mechanism

• US 5,174,716 A
• Filed: 07/23/1990
• Issued: 12/29/1992
• Est. Priority Date: 07/23/1990
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Miller, Edwin K., Hora, Petr
• Primary Examiner(s): Look, Edward K.
• Assistant Examiner(s): LARSON, JAMES
• Application Number:
  US07/556,145
• Time in Patent Office: 890 Days
• Field of Search: 416/26, 416/32, 416/46, 416/128, 416/129, 416/130, 416/152, 416/160, 416/162, 416/170 R
• US Class Current: 416/26
• CPC Class Codes: B64C 11/32 mechanical
• CPC Class Codes: B64D 2027/005 Aircraft with an unducted turbofan comprising contra-rotating rotors, e.g. contra-rotating open rotors [CROR]
• CPC Class Codes: F01D 7/00 Rotors with blades adjustable in operation; Control thereof for reversing F01D1/30
• 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
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

The invention concerns a pitch change mechanism for an aircraft propeller in which a common ring gear (51) changes pitch of all propeller blades on a given rotor simultaneously. Motion of the ring gear (51) is induced by a planet (40)-and-carrier (101) system driven by a pinion (110). Acceleration of the pinion causes a change toward flat pitch. Deceleration of the pinion causes change toward feathered pitch. If the motor driving the pinion fails, a large deceleration occurs, driving the blades to a safe, feathered position.

Claims

1. A pitch-change mechanism for aircraft propulsor blades, comprising:

a) an axis of rotation of the propulsor blades;

b) a motor rotating a gear wherein;

i) said motor includes a rotating shaft directly engaging said gear;

ii) said motor constantly rotates said gear even when blade pitch remains constant;

iii) said motor is mounted to a stationary support in such a manner that said motor rotating shaft is offset relative to said propulsor blade axis of rotation;

iv) said motor operates at maximum speed during aircraft landing when the propulsor blades are driven into a reverse pitch position; and

c) gear train means for

i) linking the gear with propulsor blades;

ii) maintaining a constant blade pitch when gear speed is constant;

iii) increasing blade pitch when gear speed decreases; and

iv) decreasing blade pitch when gear speed increases.

2. The pitch-change mechanism of claim 13 wherein said gear train means comprises:

a) a first ring gear which is fixed with respect to propulsor blades;

b) a second ring gear which is movable with respect to the propulsor blades;

c) a linkage which induces pitch-change of the propulsor blades in response to motion of the second ring gear with respect to the first ring gear; and

d) means for inducing relative rotation between said first and second ring gears, wherein said inducing means comprises a plurality of compound planet gears supported by a rotatable carrier with each of said compound planet gears including a pair of gears of different tooth number.

3. The pitch-change mechanism of claim 2, further comprising:

a) a clutch which disconnects said motor from said gear when said motor loses power;

b) a first brake which locks said rotatable planet gear carrier to said first ring gear when said motor malfunctions, thereby fixing pitch;

c) a second brake applied to said gear in order to assist in attaining a feathered pitch position; and

d) wherein said gear train means;

i) changes pitch in response to rotation of said motor regardless of whether the propulsor blades are rotating;

ii) changes pitch during rotation of the propulsor blades without said motor changing direction;

iii) provides a mechanism advantage of said gear over the propulsor blades; and

iv) causes drag that drives the propulsor blades toward a feathered pitch when said motor malfunctions and the propulsor blades are rotating.