Collapsible lift propellers

Patent metadata

Field	Value
Publication number	US-9409642-B1
Application number	US-201514749299-A
Country	US
Kind code	B1
Filing date	Jun 24, 2015
Priority date	Jun 24, 2015
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

Aerial vehicles may be equipped with collapsible lift propellers and thrust propellers. The collapsible lift propellers may include retractable tips that may pivot or rotate from a first orientation substantially co-aligned with a main body of the collapsible lift propellers during ordinary operations and a second orientation substantially transverse to the main body of the collapsible lift propellers when rotation of the collapsible lift propellers is stopped. The collapsible lift propellers may further include biasing elements, e.g., springs for biasing the retractable tips into the second orientation, and mechanical stops for inhibiting the pivoting or rotation of the retractable tips beyond the first orientation.

First claim

What is claimed is:

1. An unmanned aerial vehicle comprising:
a frame;
a lift motor mounted to the frame;
a lift propeller coupled to the lift motor;
a thrust motor mounted to the frame; and
a thrust propeller coupled to the thrust motor,
wherein the lift propeller comprises a fixed blade and a collapsible blade mounted to a hub coupled to the lift motor,
wherein the collapsible blade comprises a fixed blade root and a collapsible blade tip pivotably mounted to the fixed blade root at a spring-biased connection, and
wherein the collapsible blade tip is adapted to rotate about an axis defined by the spring-biased connection between a first orientation that is co-aligned with the fixed blade root and a second orientation that is substantially perpendicular to the fixed blade root.

2. The unmanned aerial vehicle of claim 1 ,
wherein each of the lift motor and the thrust motor are configured for simultaneous operation during a lifting of the unmanned aerial vehicle, and
wherein the lift motor is configured to be stopped during a thrusting of the unmanned aerial vehicle.

3. The unmanned aerial vehicle of claim 1 ,
wherein the fixed blade root further comprises a mechanical stop aligned to contact at least one surface of the collapsible blade tip when the collapsible blade tip is in the first orientation and to inhibit the collapsible blade tip from rotating beyond the first orientation.

4. The unmanned aerial vehicle of claim 1 ,
wherein the spring-biased connection comprises a torsion spring aligned to bias the collapsible blade tip into the second orientation.

5. The unmanned aerial vehicle of claim 1 ,
wherein the unmanned aerial vehicle is a multi-rotor vehicle including two lift motors mounted to the frame,
wherein each of the two lift motors is coupled to one of two lift propellers, and
wherein each of the two lift propellers comprises the fixed blade and the collapsible blade.

6. A propeller comprising:
at least one fixed blade mounted about a hub; and
at least one collapsible blade mounted opposite the at least one fixed blade about the hub,
wherein the at least one collapsible blade comprises a fixed blade root at a proximal end of the at least one collapsible blade and a collapsible blade tip at a distal end of the at least one collapsible blade,
wherein the collapsible blade tip is pivotably joined to the fixed blade root, and
wherein the collapsible blade tip is configured to pivot between a first orientation co-aligned with the fixed blade root and a second orientation substantially perpendicular to the fixed blade root.

7. The propeller of claim 6 ,
wherein the at least one collapsible blade further comprises a shaft assembly having a shaft pivotably joining the collapsible blade tip to the fixed blade root, and
wherein the collapsible blade tip is configured to pivot between the first orientation and the second orientation about an axis defined by the shaft.

8. The propeller of claim 7 ,
wherein the shaft assembly further comprises a biasing element configured to bias the collapsible blade tip into the second orientation.

9. The propeller of claim 8 ,
wherein the biasing element comprises a torsion spring.

10. The propeller of claim 9 ,
wherein the torsion spring has a spring constant selected based at least in part on an operational speed of the propeller, an anticipated air pressure on the collapsible blade tip when the propeller is at the operational speed or an anticipated air velocity passing over the collapsible blade tip when the propeller is at the operational speed.

11. The propeller of claim 8 ,
wherein the fixed blade further comprises a counterweight having a first mass provided at a first distance from a center of the hub.

12. The propeller of claim 11 ,
wherein at least one of the first mass or the first distance is selected based at least in part on a second mass of the shaft, a second distance of a centroid of the second mass from the center of the hub, a third mass of the biasing element or a third distance of a centroid of the biasing element from the center of the hub.

13. The propeller of claim 12 ,
wherein a first product of the first distance and the first mass is substantially equal to a sum of a second product of the second distance and the second mass and a third product of the third distance and the third mass.

14. The propeller of claim 7 , wherein the collapsible blade tip is pivotably joined to the fixed blade root at a first distance from a center of the hub, and
wherein the shaft is aligned along an axis corresponding to a centroid of a cross-section of the collapsible blade at the first distance from the center of the hub.

15. The propeller of claim 6 , wherein the fixed blade root further comprises a stop extending radially outward from the hub, and
wherein the stop is configured to contact at least one surface of the collapsible blade tip when the collapsible blade tip is in the first orientation.

16. The propeller of claim 15 , wherein the collapsible blade tip further comprises a recess provided on the at least one surface, and
wherein the recess is aligned to receive the stop when the collapsible blade tip is in the first orientation.

17. The propeller of claim 6 , wherein the hub comprises a mast opening adapted for mounting to a rotatable mast of a motor.

18. An aerial vehicle having a plurality of propellers, wherein at least one of the plurality of propellers is the propeller of claim 6 .

19. A method to operate an aerial vehicle comprising:
initiating an operation of a first motor having a first lifting propeller coupled thereto;
initiating an operation of a second motor having a second thrust propeller coupled thereto;
determining that lift from the first lifting propeller is not desired; and
stopping the operation of the first motor,
wherein the first lifting propeller comprises a shaft assembly, a fixed blade and a collapsible blade having a fixed blade root and a collapsible blade tip pivotably mounted to the fixed blade root by the shaft assembly,
wherein the collapsible blade tip is aligned to pivot about an axis defined by the shaft assembly between a first orientation substantially co-aligned with the fixed blade root and a second orientation substantially transverse to the fixed blade root,
wherein the shaft assembly further includes a torsion spring biasing the collapsible blade tip into the second position, and
wherein airflow over at least the collapsible blade tip during the operation of the first motor urges the collapsible blade tip into the first position.

20. The method of claim 19 , wherein determining that the lift from the first lifting propeller is not desired further comprises:
determining that an altitude of the aerial vehicle exceeds a predetermined threshold; and
stopping the operation of the first motor.

Assignees

• Amazon Tech Inc

Inventors

• Pingree Liam Stewart Cavanaugh

Classifications

• B64U2201/10

  autonomous, i.e. by navigating independently from ground or air stations, e.g. by using inertial navigation systems [INS] · CPC title

• B64C29/0025

  the propellers being fixed relative to the fuselage · CPC title

• B64C11/28 Primary

  Collapsible or foldable blades · CPC title

• B64C2201/108

  Operations & Transport · mapped topic

• B64C39/024

  of the remote controlled vehicle type, i.e. RPV · CPC title