Lightweight reduction gearbox

Abstract

Contemplated gearboxes combine a high numerical reduction ratio with the capability of transmitting power at a superior power-to-weight ratio using a compound star planetary gearbox configuration that is radially expanded using hollow driveshafts to link the planet gears. In most preferred compound planetary gear arrangements, planets of different diameter are torsionally connected to each other, or mesh with each other. Input and output gears counter-rotate while the planets rotate in bearings anchored to a static casing.

Description

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic of arrangements with two (or alternatively three) distributing shafts and two (or alternatively three) pinions, and either an internally- or externally-toothed ring gear.

FIG. 2 is a schematic of arrangements with two and three distributing shafts, and four and six compounded pinions, and either an internally- or externally-toothed ring.

FIG. 3 is a schematic of an arrangement with a non-meshing torque divider between two input sun gears, six distributing shafts, and 12 compounded pinions.

FIG. 4 is an axial cross-section of a single distributing shaft that would be used in accordance with the gearbox of FIG. 1.

FIG. 5 is an axial cross-section of a single distributing shaft that would be used in accordance with the gearbox of FIG. 2.

FIG. 6 is an axial view showing the driving planet of FIG. 2 in force balance between two driven face gears.

FIG. 7 is an axial view showing the driving sun gear of FIG. 2 in force balance among three driven face gears.

FIG. 8 is a cross-section of the mutual support bearing arrangement between the output pinion and the output ring gear.

FIG. 9 is a partial perspective end view of a possible connection between an output ring gear and the load (or input device) consisting of a series of tangential links.

FIG. 10 is a graph depicting trendlines for weight to torque/speed ratio for various time periods.

Claims

1. A torque multiplier device, comprising a sun gear and ring gear, coupled by a compound planetary set.

2. The device of claim 1, wherein the compound planetary set comprises at least first and second pinions.

3. The device of claim 2, wherein the first and second pinions have axes of rotation that are inclined relative to a principal axis of rotation of an input.

4. The device of claim 3, wherein the axes of rotation are fixed relative to a casing.

5. The device of claim 1, wherein the sizes of the sun and ring gears are such that they achieve a multiplication of at least 30.

6. The device of claim 1, wherein the sizes of the sun and ring gears are such that they achieve a multiplication of at least 50.

7. The device of claim 1, comprising a torsionally stiff and weight efficient connection such that the device exhibits a torque to weight ratio of greater than a 2010 parametric norm for lightweight high torque gearboxes.

8. The device of claim 1, wherein the size of the ring gear is selected to have a diameter effective for the device to consistently and reliably transfer at least 50,000 ft-lb of torque.

9. The device of claim 1, wherein the size of the ring gear is selected to have a diameter effective for the device to consistently and reliably transfer at least of 100,000 ft-lb of torque.

10. The device of claim 1, wherein the size of the ring gear is selected to have a diameter effective for the device to consistently and reliably transfer less than 5000 ft-lb of torque.

11. The device of claim 2, wherein each of the pinions includes a deflection accepting coupling.

12. The device of claim 11, wherein the deflection accepting coupling is selected from the group consisting of a shaped splice and a flexible bellows.

13. The device of claim 2, wherein the compound planetary set further comprises a third pinion.

14. The device of claim 13, wherein the first and second pinions are configured to continue operation upon catastrophic failure of the third pinion.

15. The device of claim 1, wherein at least one of the pinions has at least one end that is supported by an adjacent mesh with a need for bearing support.

16. A method of weight-efficiently multiplying torque comprising increasing a radius of effort by at least 50% at a cost of increasing weight of a torque multiplier by no more than 50%.

17. The method of claim 16, further comprising increasing the radius of effort by at least 100% at a cost of increasing weight by no more than 50%.

18. The method of claim 16, further comprising increasing the a radius of effort by at least 100% at a cost of increasing weight by no more than 25%.

19. The method of claim 16, wherein the step of increasing the radius of effort comprises using a polymeric shaft to couple a ring gear with a sun gear.

20. The method of claim 16, wherein the step of increasing the radius of effort comprises using a hollow shaft to couple a ring gear with a sun gear.

21. The method of claim 16, wherein the step of increasing the radius of effort comprises using a shaft to couple a ring gear with a sun gear, wherein the shaft occupies a distance of at least 75% of a radius of the ring gear.

22. The method of claim 16, further comprising coupling the torque multiplier to a rotor of a rotorcraft.