# US 10,308,357 B2 · Methods and apparatus to control pitch and twist of blades

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- Number: US 10,308,357 B2
- Document ID: US10308357B2
- Status: Granted
- Kind: B2
- Application number: 14/502,655
- Filed: 2014-09-30
- Published: 2016-03-31
- Granted: 2019-06-04
- Earliest claimed: 2014-09-30
- Assignees: The Boeing Company
- Applicants: The Boeing Company
- Inventors: Ian M. Gunter; Thomas R. Kenow; Chris Jorgens
- Web page: https://patentgrep.com/patent/US10308357B2

## CPC

- B64C 27/72: Means acting on blades
- B64C 27/605: including swash plate, spider or cam mechanisms
- B64C 2027/7244: {by using dedicated actuators}
- B64C 2027/7255: {using one or more swash plates}
- Y02T 50/30: Wing lift efficiency
- B64C: AEROPLANES; HELICOPTERS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

Methods and apparatus to control pitch and twist of blades are disclosed. An example apparatus includes a twist input assembly driven by a drive shaft that drives a rotation of blades of a rotorcraft, the twist input assembly comprising a twist shaft, a first gear set driven by the drive shaft, and a first frequency controller to create a first rotational speed difference between a first gear of the first gear set and the drive shaft, the first rotational speed difference to cause the twist shaft to oscillate. The examples apparatus includes a pitch input assembly driven by the drive shaft, the pitch input assembly comprising a pitch link in communication with a first one of the blades of the rotorcraft, a second gear set driven by the drive shaft, and a second frequency controller to create a second rotational speed difference between a second gear of the second gear set and the drive shaft, the second rotational speed difference to cause the pitch link to oscillate.

## Claims

### Claim 1

A control apparatus comprising:
a drive shaft to drive a rotation of a blade of a rotorcraft;
a twist shaft to be driven by the drive shaft, the twist shaft to provide a twist input to the blade, the twist shaft being concentric with the drive shaft; and
gears to convert rotation of the drive shaft into an oscillation of the twist shaft.

### Claim 2 (depends on 1)

The apparatus of claim 1, further comprising a brake to create a difference between a first rotational speed of a first one of the gears and a second rotational speed of the drive shaft.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein a magnitude of the difference created by the brake determines a frequency of the oscillation of the twist shaft.

### Claim 4 (depends on 1)

The apparatus of claim 1, further comprising a drive to travel about the drive shaft and to rotate about a center of the drive in accordance with a brake applied to a first one of the gears.

### Claim 5 (depends on 4)

The apparatus of claim 4, further comprising first and second arms operatively coupling the drive to the twist shaft, wherein rotation of the drive about the center of the drive causes the second arm to oscillate the twist shaft.

### Claim 6 (depends on 4)

The apparatus of claim 4, wherein the drive is to ride on a disc-shaped extension of the drive shaft.

### Claim 7 (depends on 1)

The apparatus of claim 1, wherein a first one of the gears is in communication with a frequency controller, the frequency controller to slow a rotation of the first one of the gears to cause the oscillation of the twist shaft.

### Claim 8 (depends on 1)

The apparatus of claim 1, further comprising a phase controller to alter a phase of the oscillation of the twist shaft.

### Claim 9 (depends on 8)

The apparatus of claim 8, wherein the phase controller is to rotate a ring on which one of the gears is mounted.

### Claim 10

An apparatus, comprising:
a twist input assembly driven by a drive shaft that drives a rotation of blades of a rotorcraft, the twist input assembly comprising:
a twist shaft;
a first gear set driven by the drive shaft; and
a first frequency controller to create a first rotational speed difference between a first gear of the first gear set and the drive shaft, the first rotational speed difference to cause the twist shaft to oscillate; and
a pitch input assembly driven by the drive shaft, the pitch input assembly comprising:
a pitch link in communication with a first one of the blades of the rotorcraft;
a second gear set driven by the drive shaft; and
a second frequency controller to create a second rotational speed difference between a second gear of the second gear set and the drive shaft, the second rotational speed difference to cause the pitch link to oscillate.

### Claim 11 (depends on 10)

The apparatus of claim 10, wherein the pitch input assembly is to move toward and away from the twist input assembly in response to collective control input and cyclic control input.

### Claim 12 (depends on 10)

The apparatus of claim 10, wherein the twist input assembly further comprises a first phase controller to alter a first phase of a first oscillation of the twist shaft by rotating a third gear of the first gear set.

### Claim 13 (depends on 12)

The apparatus of claim 12, wherein the pitch input assembly further comprises a second phase controller to alter a second phase of a second oscillation of the pitch link by rotating a fourth gear of the second gear set.

### Claim 14 (depends on 10)

The apparatus of claim 10, wherein the twist shaft is concentric with the drive shaft.

### Claim 15 (depends on 10)

The apparatus of claim 10, wherein the twist input assembly further comprises a drive riding on a disc-shaped extension of the drive shaft, the drive to spin about a center axis of the drive in accordance with the first rotational speed difference.

### Claim 16 (depends on 15)

The apparatus of claim 15, wherein the twist input assembly further comprises pivotably coupled arms to convert the spin of the drive into an oscillation of the twist shaft.

### Claim 17

A method comprising:
reducing, by a first amount, a first rotational speed of a first gear in communication with a second gear to cause a twist shaft oscillation having a first frequency, wherein a difference between a second rotational speed of the second gear and a third rotational speed of a drive shaft causes the twist shaft oscillation; and
reducing, by a second amount different than the first amount, the first rotational speed of the first gear to cause the twist shaft oscillation to have a second frequency different than the first frequency.

### Claim 18 (depends on 17)

The method of claim 17, wherein reducing the first rotational speed comprises applying a brake to the first gear.

### Claim 19 (depends on 17)

The method of claim 17, further comprising rotating an adjustable ring to control a phase of the twist shaft oscillation, wherein a third gear in communication with the first and second gears is coupled to the adjustable ring.

### Claim 20 (depends on 17)

The method of claim 17, further comprising reducing, by a third amount, a fourth rotational speed of a third gear in communication with a fourth gear to cause a pitch link oscillation having a third frequency, wherein a difference between a fourth rotational speed of the fourth gear and the third rotational speed of the drive shaft causes the pitch link oscillation.

### Claim 21 (depends on 20)

The method of claim 20, further comprising reducing, by a fourth amount different than the third amount, the fourth rotational speed of the third gear to cause the pitch link oscillation to have a fourth frequency different than the third frequency.