# US 11,440,653 B2 · Anti-drive mechanism for rotary aircraft control

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- Number: US 11,440,653 B2
- Document ID: US11440653B2
- Status: Granted
- Kind: B2
- Application number: 16/894,321
- Filed: 2020-06-05
- Published: 2021-12-09
- Granted: 2022-09-13
- Earliest claimed: 2020-06-05
- Assignees: Textron Innovations Inc.
- Applicants: Bell Textron Inc.
- Inventors: Terry K. Thompson; Mark Wiinikka; Bryan Baskin; Vince Calabrese; Samantha Renee Lucero
- Web page: https://patentgrep.com/patent/US11440653B2

## CPC

- B64C 27/605: including swash plate, spider or cam mechanisms
- B64C 27/14: Direct drive between power plant and rotor hub
- B64C: AEROPLANES; HELICOPTERS

## Abstract

One embodiment includes a swashplate assembly for a rotary aircraft, including: a rotating ring configured to rotate with a drive shaft of the rotary aircraft; a non-rotating ring coupled to the rotating ring and rotationally decoupled from the rotating ring, wherein the non-rotating ring does not rotate with the rotating ring and drive shaft; an outer casing disposed around the gearbox; and an anti-drive mechanism to maintain the outer casing rotationally stationary relative to the gearbox, the anti-drive mechanism including a key and slot system between the gearbox and the outer casing.

## Claims

### Claim 1

A swashplate assembly for a rotary aircraft, comprising:
a rotating ring configured to rotate with a drive shaft of the rotary aircraft;
a non-rotating ring coupled to the rotating ring and rotationally decoupled from the rotating ring, wherein the non-rotating ring does not rotate with the rotating ring and drive shaft;
an outer casing to fit around a gearbox, wherein a contact surface between the outer casing and the gearbox is unsplined; and
an anti-drive mechanism to maintain the outer casing rotationally stationary relative to the gearbox, the anti-drive mechanism comprising an unpinned key-and-slot system between the gearbox and the outer casing on the unsplined contact surface, the key-and-slot system comprising a plurality of keys disposed equidistantly around a circumference of the gearbox, the keys having a long axis along a height of the gearbox with a length longer than a height of the outer casing, and a short axis along a circumference of the gearbox having a width substantially shorter than the long axis, and a plurality of slots disposed on the outer casing having position and size to securely enclose the plurality of keys.

### Claim 2 (depends on 1)

The swashplate assembly of claim 1, wherein the non-rotating ring is coupled to the rotating ring via a duplex or triplex bearing.

### Claim 3 (depends on 1)

The swashplate assembly of claim 1, wherein the outer casing comprises a tilt ball.

### Claim 4 (depends on 1)

The swashplate assembly of claim 1, wherein slots of the key-and-slot system comprise replaceable wear items comprising a polytetrafluoroethylene liner.

### Claim 5 (depends on 1)

The swashplate assembly of claim 1, further comprising pins and keys to align the outer casing with the non-rotating ring.

### Claim 6 (depends on 1)

The swashplate assembly of claim 1, wherein the key-and-slot system comprises a plurality of key-and-slot pairs.

### Claim 7 (depends on 6)

The swashplate assembly of claim 6, wherein the key-and-slot pairs are disposed substantially equidistantly around a circumference of the unsplined contact surface.

### Claim 8 (depends on 1)

The swashplate assembly of claim 1, wherein the key of the key-and-slot system is located on a circumference of a gear box.

### Claim 9 (depends on 8)

The swashplate assembly of claim 8, further comprising a tilt ball around the gear box, wherein the tilt ball contains the slots to mate with keys of the key-and-slot system.

### Claim 10 (depends on 8)

The swashplate assembly of claim 8, wherein the key is steel.

### Claim 11 (depends on 8)

The swashplate assembly of claim 8, wherein the key is attached to the gear box.

### Claim 12 (depends on 11)

The swashplate assembly of claim 11, wherein the key is aluminum.

### Claim 13 (depends on 11)

The swashplate assembly of claim 11, wherein the key further comprises a chrome wear surface.

### Claim 14 (depends on 13)

The swashplate assembly of claim 13, further comprising a tungsten carbide coating on the aluminum key.

### Claim 15

A non-rotating ring for a swashplate of a rotary aircraft control system, comprising:
a through hole to receive a drive shaft of a rotary aircraft; and
a plurality of keys affixed to and disposed substantially equidistantly around an unsplined inner diameter of the non-rotating ring, the keys to engage an outer casing of a tilt ball, and to permit radial movement around a spherical shape of the tilt ball while preventing rotation of the non-rotating ring relative to the tilt ball, wherein an interface between the tilt ball and the non-rotating ring is unpinned, and wherein the plurality of keys have a long axis along a height of the non-rotating ring with a length longer than a height of the outer casing, and a short axis along a circumference of the non-rotating ring having a width substantially shorter than the long axis.

### Claim 16 (depends on 15)

The non-rotating ring of claim 15, wherein the keys are attached to the non-rotating ring.

### Claim 17 (depends on 15)

The non-rotating ring of claim 15, wherein the plurality of keys are aluminum bronze.

### Claim 18 (depends on 15)

The non-rotating ring of claim 15, wherein a plurality of slots in the tilt ball comprise a tungsten carbide wear surface.

### Claim 19

A rotary aircraft, comprising:
an airframe;
a main rotor assembly;
a gearbox and drive shaft to drive the main rotor assembly;
a pilot control input;
a swashplate assembly to translate pilot control inputs to motion of the main rotor assembly, the swashplate assembly comprising:
a rotating ring to engage the main rotor assembly and to rotate with the drive shaft;
a non-rotating ring mechanically coupled to the rotating ring and rotationally decoupled from the rotating ring, wherein the non-rotating ring does not rotate with the rotating ring and the drive shaft;
a tilt ball mechanically coupled to the non-rotating ring to prevent the tilt ball and non-rotating ring from rotating relative to one another; and
an unpinned key-and-slot system on an unsplined mechanical interface between a contact surface of the tilt ball and the gearbox, comprising a plurality of keys disposed equidistantly around a circumference of the gearbox, the plurality of keys having a long axis along a height of the gearbox with a length longer than a height of the tilt ball, and a short axis along a circumference of the gearbox having a width substantially shorter than the long axis, and a plurality of slots disposed on the tilt ball having position and size to securely enclose the plurality of keys.

### Claim 20 (depends on 19)

The rotary aircraft of claim 19, wherein the non-rotating ring is coupled to the rotating ring via a duplex or triplex bearing.