Direct drive for exercise machines
View Patent ↗An exercise machine includes a support structure, a crank shaft rotatably mounted on the support structure, a first planetary gear set operatively coupled to the crank shaft so that the crank shaft provides an input for the first planetary gear set, a second planetary gear set operatively coupled to the first planetary gear set so that an output of the first planetary gear set provides an input for the second planetary gear set, and a flywheel rotatably operatively coupled to the second planetary gear set so that an output of the second planetary gear set rotates the flywheel.
1. An exercise machine, comprising:
a support structure;
a crank shaft rotatably mounted on the support structure;
a first planetary gear set, comprising:
a first sun gear rotatably mounted on the crank shaft,
a first planet carrier mounted on the crank shaft and secured thereto for rotation with the crank shaft,
a first planet gear rotatably mounted on the first planet carrier and meshing with the first sun gear, and
a first ring gear encircling and meshing with the first planet gear;
a second planetary gear set, comprising:
a second sun gear rotatably mounted on the crank shaft,
a second planet carrier rotatably mounted on the crank shaft,
a second planet gear rotatably mounted on the second planet carrier and meshing with the second sun gear, and
a second ring gear encircling and meshing with the second planet gear, wherein the first planetary gear set is operatively connected to the second planetary gear set such that an output rotation of the first planetary gear set causes an input rotation of the second planetary gear set; and
a flywheel rotatably mounted on the crank shaft and being operatively connected to the second planetary gear set such that output rotation of the second planetary gear set causes rotation of the flywheel.
2. The exercise machine of claim 1 , wherein the first sun gear is secured to the second planet carrier for rotation therewith so that an output rotation of the first sun gear rotates the second planet carrier to cause an input rotation of the second planetary gear set, and wherein the second sun gear is secured to the flywheel for rotation therewith so that an output rotation of the second sun gear rotates the flywheel.
3. The exercise machine of claim 1 , comprising:
a first crank arm having a first end rigidly attached to one end of the crank shaft and extending radially from the crank shaft and terminating at a second end;
a second crank arm having a first end rigidly connected to an opposite end of the crank shaft from the first crank arm and extending radially from the crank shaft in a direction 180° out of phase with the first crank arm and terminating at a second end;
a first reciprocating foot support having a first end pivotally linked to the second end of the first crank arm; and
a second reciprocating foot support having a first end pivotally linked to the second end of the second crank arm, wherein the first and second reciprocating foot supports each have second ends operatively connected to the support structure so that the first and second reciprocating foot supports travel about closed paths having a stride length upon rotation of the crank shaft.
4. The exercise machine of claim 1 , wherein the first planetary gear set comprises three first planet gears rotatably mounted on and circumferentially spaced around the first planet carrier and meshing with the first sun gear and the first ring gear, wherein the second planetary gear set comprises three second planet gears rotatably mounted on and circumferentially spaced around the second planet carrier meshing with the second sun gear and the second ring gear.
5. The exercise machine of claim 1 , wherein the first planetary gear set has a gear ratio of 5 to 1.
6. The exercise machine of claim 5 , wherein the first sun gear comprises 48 gear teeth, the first planet gear comprises 72 gear teeth and the first ring gear comprises 192 gear teeth.
7. The exercise machine of claim 1 , wherein the first ring gear comprises an annular first ring outer housing and a first inner ring gear having gear teeth and being disposed within the first ring outer housing.
8. The exercise machine of claim 1 , wherein the second planetary gear set has a gear ratio of 5 to 1.
9. The exercise machine of claim 8 , wherein the second sun gear comprises 48 gear teeth, the second planet gear comprises 72 gear teeth and the second ring gear comprises 192 gear teeth.
10. The exercise machine of claim 1 , wherein the second ring gear comprises an annular second ring outer housing and a second inner ring gear having gear teeth and being disposed within the second ring outer housing.
11. The exercise machine of claim 1 , wherein a first gear ratio of the first planetary gear set is equal to a second gear ratio of the second planetary gear set.
12. The exercise machine of claim 1 , wherein a ratio of a number of rotations of the flywheel to a number of rotations of the crank shaft is 25 to 1.
13. The exercise machine of claim 10 , wherein the first planetary gear set has a gear ratio of 5 to 1.
14. The exercise machine of claim 1 , wherein a ratio of a number of rotations of the flywheel to a number of rotations of the crank shaft is 49 to 1.
15. The exercise machine of claim 1 , wherein a first gear ratio of the first planetary gear set is not equal to a second gear ratio of the second planetary gear set.
16. The exercise machine of claim 1 , wherein the crank shaft, the first and second planetary gear sets and the flywheel are disposed proximate a rearward end of the support structure.
17. The exercise machine of claim 1 , wherein the crank shaft, the first and second planetary gear sets and the flywheel are disposed proximate a forward end of the support structure.
18. An elliptical exercise machine, comprising:
a support structure;
a crank shaft rotatably mounted on the support structure;
a first planetary gear set operatively coupled to the crank shaft so that the crank shaft provides an input for the first planetary gear set;
a second planetary gear set operatively coupled to the first planetary gear set so that an output of the first planetary gear set provides an input for the second planetary gear set; and
a flywheel rotatably operatively coupled to the second planetary gear set so that an output of the second planetary gear set rotates the flywheel.
19. The elliptical exercise machine of claim 18 , comprising:
a first crank arm having a first end rigidly attached to one end of the crank shaft and extending radially from the crank shaft and terminating at a second end;
a second crank arm having a first end rigidly connected to an opposite end of the crank shaft from the first crank arm and extending radially from the crank shaft in a direction 180° out of phase with the first crank arm and terminating at a second end;
a first reciprocating foot support having a first end pivotally linked to the second end of the first crank arm; and
a second reciprocating foot support having a first end pivotally linked to the second end of the second crank arm, wherein the first and second reciprocating foot supports each have second ends operatively connected to the support structure so that the first and second reciprocating foot supports travel about closed paths having a stride length upon rotation of the crank shaft.
20. The elliptical exercise machine of claim 19 , wherein a ratio of a number of rotations of the flywheel to a number of rotations of the crank shaft is 25 to 1.
21. The elliptical exercise machine of claim 19 , wherein a first gear ratio of the first planetary gear set is equal to a second gear ratio of the second planetary gear set.
22. A direct drive mechanism for an elliptical exercise machine, comprising:
a crank shaft rotatably mounted on a support structure of the elliptical exercise machine;
a first planetary gear set, comprising:
a first sun gear rotatably mounted on the crank shaft,
a first planet carrier mounted on the crank shaft and secured thereto for rotation with the crank shaft, three first planet gears rotatably mounted on and circumferentially spaced around the first planet carrier and meshing with the first sun gear, and
a first ring gear encircling and meshing with the first planet gears;
a second planetary gear set, comprising:
a second sun gear rotatably mounted on the crank shaft,
a second planet carrier rotatably mounted on the crank shaft and having the first sun gear secured thereto for rotation there with, three second planet gears rotatably mounted on and circumferentially spaced around the second planet carrier and meshing with the second sun gear, and
a second ring gear encircling and meshing with the three second planet gears; and
a flywheel rotatably mounted on the crank shaft and having the second sun gear secured thereto for rotation there with.
23. The direct drive mechanism of claim 22 , comprising:
a first crank arm having a first end rigidly attached to one end of the crank shaft and extending radially from the crank shaft and terminating at a second end; and
a second crank arm having a first end rigidly connected to an opposite end of the crank shaft from the first crank arm and extending radially from the crank shaft in a direction 180° out of phase with the first crank arm and terminating at a second end.