Propeller blade leading edge serrations for improved sound control

• US 10,099,773 B2
• Filed: 12/18/2015
• Issued: 10/16/2018
• Est. Priority Date: 12/18/2015
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Beckman, Brian C., Kimchi, Gur, Ko, Allan
• Primary Examiner(s): O'Hara, Brian M
• Application Number:
  US14/975,265
• Publication Number:
  US 20170174319A1
• Time in Patent Office: 1,033 Days
• CPC Class Codes: B64C 11/00 Propellers, e.g. of ducted type; Features common to propellers and rotors for rotorcraft
• CPC Class Codes: B64C 11/008 characterised by vibration absorbing or balancing means
• CPC Class Codes: B64C 11/18 Aerodynamic features
• CPC Class Codes: B64C 11/20 Constructional features
• CPC Class Codes: B64C 2220/00 Active noise reduction systems
• CPC Class Codes: B64C 2230/14 achieving noise reductions
• CPC Class Codes: B64C 2230/28 at propeller or rotor blades
• CPC Class Codes: B64C 23/06 by generating vortices
• CPC Class Codes: B64U 10/14 with four distinct rotor axes, e.g. quadcopters
• CPC Class Codes: B64U 20/20 for noise reduction
• CPC Class Codes: B64U 2101/64 for parcel delivery or retrieval
• CPC Class Codes: B64U 30/20 Rotors; Rotor supports
• CPC Class Codes: B64U 50/19 using electrically powered motors
• CPC Class Codes: B64U 50/31 generated by photovoltaics
• CPC Class Codes: Y02T 50/10 Drag reduction
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

Sounds are generated by an aerial vehicle during operation. For example, the motors and propellers of an aerial vehicle generate sounds during operation. Disclosed are systems, methods, and apparatus for actively adjusting the position of one or more propeller blade treatments of a propeller blade of an aerial vehicle during operation of the aerial vehicle. For example, the propeller blade may have one or more propeller blade treatments that may be adjusted between two or more positions. Based on the position of the propeller blade treatments, the airflow over the propeller is altered, thereby altering the sound generated by the propeller when rotating. By altering the propeller blade treatments on multiple propeller blades of the aerial vehicle, the different sounds generated by the different propeller blades may effectively cancel, reduce, and/or otherwise alter the total sound generated by the aerial vehicle.

Claims

1. An aerial vehicle comprising:

a first motor configured to rotate a propeller such that the propeller generates a lifting force;

the propeller including;

a hub that is coupled to the motor so that the motor can rotate the propeller;

a propeller blade extending from the hub, the propeller blade including;

a leading edge;

a tip;

a trailing edge; and

a plurality of serrations protruding from the propeller blade along at least a portion of the leading edge of the propeller blade;

a controller coupled to at least some of the plurality of serrations and configured to move the at least some of the plurality serrations while the propeller blade is rotating, the controller including an adjustment arm that extends along the propeller blade, contacts the at least some of the plurality of serrations, and moves between a first adjustment arm position and a second adjustment arm position; and

a sensor configured to monitor a sound generated around the aerial vehicle; and

wherein the controller moves the adjustment arm between the first adjustment arm position and the second adjustment arm position based at least in part on the sound.

2. The aerial vehicle of claim 1, wherein:

when the adjustment arm is in the first adjustment arm position, the at least some of the plurality of serrations are in a first serration position, and

when the adjustment arm is in the second adjustment arm position, the at least some of the plurality of serrations are in a second serration position that is different than the first serration position.

3. The aerial vehicle of claim 2, wherein:

the at least some of the plurality of serrations cause the propeller blade to;

generate a first sound when the at least some of the plurality of serrations are in the first serration position and the propeller blade is rotating at a first speed; and

generate a second sound when the at least some of the plurality of serrations are in the second serration position and the propeller blade is rotating at the first speed; and

the controller moves the adjustment arm from the first adjustment arm position to the second adjustment arm position when the second sound is less than the first sound.

4. The aerial vehicle of claim 1, wherein:

at least one of a first length or a first curvature of a first serration of the plurality of serrations is different than at least one of a second length or a second curvature of a second serration of the plurality of serrations.

5. A propeller blade, comprising:

a hub;

a tip;

a surface area that extends between the hub and the tip, the surface area having an upper side, a lower side, a leading edge that extends from the hub to the tip, and a trailing edge;

a plurality of serrations coupled to the leading edge of the propeller blade; and

a controller configured to alter a position of a first set of serrations of the plurality of serrations between a first position and a second position, the controller including;

a communication component configured to receive a wireless communication that indicates whether the first set of serrations is to be in the first position or the second position; and

an actuator in contact with each serration of the first set of serrations and configured to move each serration of the first set of serrations between the first position and the second position based at least in part on the indication included in the wireless communication.

6. The propeller blade of claim 5,

wherein the propeller blade generates a first sound when rotating and the first set of serrations is in the first position and generates a second sound when rotating and the first set of serrations is in the second position.

7. The propeller blade of claim 6, wherein the first set of serrations includes at least one serration of the plurality of serrations.

8. The propeller blade of claim 6, wherein:

when each serration of the first set of serrations is in the first position, each serration is retracted behind the leading edge of the propeller blade; and

when each serration of the first set of serrations is in the second position, each serration extends beyond the leading edge of the propeller.

9. The propeller blade of claim 6, wherein:

the controller is configured to alter a position of a second set of serrations of the plurality of serrations between a third position and a fourth position;

the propeller blade generates a third sound when rotating and the first set of serrations is in the first position and the second set of serrations is in the third position; and

the propeller blade generates a fourth sound when rotating and the first set of serrations is in the second position and the second set of serrations is in the fourth position.

10. The propeller blade of claim 5, further comprising:

a power supply included in the propeller blade and configured to provide power to the actuator.

11. The propeller blade of claim 10, wherein the power supply is at least one of a fuel cell, a battery, or a solar panel.

12. The propeller blade of claim 5, wherein at least some of the plurality of serrations vary in at least one of a size, a shape, a length, a diameter, a curvature, or a material.

13. An aerial vehicle, comprising:

a frame;

a motor coupled to the frame;

a propeller coupled to and rotatable by the motor;

a first plurality of serrations positioned on the propeller, wherein a sound generated by the propeller when the propeller is rotating is altered based at least in part on a position of each of the first plurality of serrations;

a second plurality of serrations positioned on the propeller, wherein the sound generated by the propeller when the propeller is rotating is further altered based at least in part on a position of each of the second plurality of serrations;

a sensor configured to measure a sound generated by the aerial vehicle; and

a controller configured to send instructions to alter a position of at least one of the first plurality of serrations or the second plurality of serrations; and

wherein the instructions are based at least in part on the sound measured by the sensor.

14. The aerial vehicle of claim 13, wherein:

the second plurality of serrations are positioned toward a tip of the propeller and alter sound generated by a tip vortex resulting from the rotation of the propeller; and

the first plurality of serrations are positioned along a leading edge of the propeller and alter sound generated by air passing across the propeller.

15. The aerial vehicle of claim 13, wherein the first plurality of serrations are formed of a fibrous material that flexes during rotation of the propeller.

16. The aerial vehicle of claim 13,

wherein the controller is configured to cause a position of the first plurality of serrations to be altered while the propeller is rotating.

17. The aerial vehicle of claim 13, further comprising:

a flexible fringe extending from a trailing edge of the propeller, the fringe configured to disrupt air passing the propeller and alter a sound generated by the air passing the propeller as the propeller rotates; and

a sound dampening material affixed to at least one of an upper side of the propeller or a lower side of the propeller and configured to absorb sound generated by air passing the propeller as the propeller rotates.