Variable ratio transmission elements for motor drive shafts

• US 20050162049A1
• Filed: 07/16/2004
• Published: 07/28/2005
• Est. Priority Date: 01/28/2004
• Status: Active Grant

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Krill, Jerry A.
• Granted Patent: US 7,075,213 B2
• Time in Patent Office: Days
• US Class Current: 310/328
• CPC Class Codes: F16D 13/12 with an expansible band or coil co-operating with the inner surface of a drum or the like F16D13/02 takes precedence; similar brakes F16D51/02
• CPC Class Codes: F16D 28/00 Electrically-actuated clutches arrangements for synchronisation F16D23/02; clutches actuated directly by means of an electromagnet F16D27/00; automatic clutches F16D43/00 - F16D45/00; external control F16D48/00
• CPC Class Codes: F16H 15/04 Gearings providing a continuous range of gear ratios
• CPC Class Codes: Y10S 310/80 Piezoelectric polymers, e.g. PVDF

Abstract

A motor transmission element includes an axle, an expandable circumferential component and multiple rolled electroactive polymer (EAP) devices. The circumferential component is located at a contact radius from the axle for connection to a different rotating body and is mechanically connected to the axle. The rolled EAP devices are mechanically connected to the circumferential component and the axle. Each rolled EAP device has a pair of input electrodes and is configured to deform substantively parallel to a roll longitudinal axis upon application of a voltage difference. Deformation of a rolled EAP device causes a change in the contact radius. A voltage difference that expands the rolled EAP device increases the contact radius, and thereby the circumference of the transmission element. By varying the voltage, a continuously variable ratio can be achieved between a rate of rotation of the transmission element and a rate of rotation of the second body.

Claims

1. A motor transmission apparatus comprising:

an axle;

an expandable circumferential component at a contact radius from the axle mechanically connected to the axle, said circumferential component for connection to a different rotating body;

a plurality of rolled electroactive polymer devices mechanically connected to the expandable circumferential component and the axle,

wherein

each rolled electroactive polymer device has a first pair of input electrodes and is configured to deform substantively parallel to a roll longitudinal axis upon application of an electric potential difference across the first pair of input electrodes, and

deformation of a rolled electroactive polymer device causes a change in the contact radius.

2. A motor transmission apparatus comprising:

an axle;

a plurality of expandable spokes connected to the axle;

a plurality of rolled electroactive polymer devices arranged azimuthally around the axle at a particular radius, and mechanically connected to the plurality of expandable spokes,

wherein

each rolled electroactive polymer device has a first pair of input electrodes and is configured to deform substantively parallel to a roll longitudinal axis upon application of an electric potential difference across the first pair of input electrodes, and

deformation of a rolled electroactive polymer device causes a change in the particular radius.

3. The apparatus as recited in claim 2, wherein:

the apparatus further includes an expandable circumferential component at a contact radius, said circumferential component for connection to a different rotating body; and

deformation of the rolled electroactive polymer device causes a change in the contact radius that is based on the change in the particular radius.

4. The apparatus as recited in claim 2 wherein the axle is configured for direct connection to a rotating drive shaft of a motor.

5. The apparatus as recited in claim 3 wherein the different rotating body is connected to a rotating drive shaft of a motor.

6. The apparatus as recited in claim 3, wherein the expandable circumferential component is mechanically connected to a spoke of the plurality of expandable spokes.

7. The apparatus as recited in claim 3, wherein the expandable circumferential component is mechanically connected to a rolled electroactive polymer device of the plurality of rolled electroactive polymer devices.

8. The apparatus as recited in claim 2, further comprising a different plurality of rolled electroactive polymer devices arranged azimuthally about the axle at a different radius, and mechanically connected to the plurality of expandable spokes.

9. The apparatus as recited in claim 3, wherein:

the expandable circumferential component comprises a plurality of rows of gear teeth;

each row of the plurality of rows of gear teeth slides independently of a different row of the plurality of rows of gear teeth with a change in circumference of the expandable circumferential component; and

teeth in each of the plurality of rows are aligned between teeth on the different rotating body at a plurality of values for the contact radius.

10. The apparatus as recited in claim 3, wherein the expandable circumferential component is a rough surface that causes friction to engage a surface of a connection to the different rotating body.

11. The apparatus as recited in claim 2, wherein each rolled electroactive polymer device has a second pair of input electrodes and is configured to deform independently along the roll longitudinal axis on one side of the rolled electroactive polymer device upon application of an electric potential difference across the second pair of input electrodes.

12. The apparatus as recited in claim 10, further comprising an electrical distributor to supply a first voltage to the first pair of electrodes and a different second voltage to the second pair of electrodes to cause a side of the rolled electroactive polymer device closer to the axle to have a shorter length than an opposite side of the rolled electroactive polymer device.

13. The apparatus as recited in claim 2, wherein at least one of said axle and said plurality of expandable spokes comprises a structure with a specific gravity substantively similar to honeycombed plastic.

14. The apparatus as recited in claim 2, wherein at least one of said axle and said plurality of expandable spokes are made to have low radar reflectivity compared to a same surface area of metal.

15. The apparatus as recited in claim 3, wherein said expandable circumferential component comprises a structure with a specific gravity substantively similar to honeycombed plastic.

16. The apparatus as recited in claim 2, wherein said expandable circumferential component is made to have low radar reflectivity compared to a same surface area of metal.

17. The apparatus as recited in claim 2, further comprising an electrical distributor to supply a first voltage to the first pair of electrodes.

18. The apparatus as recited in claim 17, an expandable spoke of said plurality of expandable spokes further comprising an electrical connection for connecting an electrode of the first pair of electrodes to the electrical distributor.

19. The apparatus as recited in claim 2, wherein an expandable spoke of said plurality of expandable spokes is electrically connected to ground and electrically connected to an electrode of the first pair of electrodes.

20. The apparatus as recited in claim 2, further comprising a ring element for mechanically connecting a rolled electroactive polymer device azimuthally to a spoke of the plurality of expandable spokes.

21. The apparatus as recited in claim 20, further comprising an expandable spoke attached to the ring element and not attached to the axle.

22. A motor transmission apparatus comprising:

an axle;

an expandable circumferential component at an outer radius from the axle; and

a plurality of rows of gear teeth disposed along the expandable circumferential component,

wherein;

each row of the plurality of rows of gear teeth slides with circumference changes of the expandable circumferential component independently of a different row of the plurality of rows of gear teeth; and

teeth in each of the plurality of rows are aligned between teeth on a connection to a different rotating body at a plurality of values for the outer radius.