Bicycle gearbox having segmented sprockets
A gearbox may include a drive spindle and several interconnected gear clusters arranged in a housing. A first of the gear clusters is coaxially fastened to the spindle, and has an outboard gear and an inboard gear. The first gear cluster drives a belt to operate one or more of the other gear clusters, and the inboard gear is physically divided into a plurality of segments. A shifting system for the gearbox includes an actuator configured to urge the segments of the inboard gear of the first gear cluster into and out of the plane of the belt, such that a gear ratio of the gearbox is changeable without displacing the belt out of the plane.
1. A gearbox for a vehicle, the gearbox comprising:
a drive spindle;
a layshaft spaced from and parallel to the spindle;
a first gear cluster coaxially fastened to one of the spindle or the layshaft and rotatable therewith, the first gear cluster including an outboard gear and an inboard gear, wherein the inboard gear is physically divided into a plurality of segments;
a second gear cluster coaxially fastened to the other of the spindle or the layshaft and rotatable therewith, the second gear cluster having one or more gears;
a continuous belt coupling the first gear cluster to the second gear cluster, such that the belt defines a plane, wherein the segments of the inboard gear of the first gear cluster are each movable into and out of the plane;
a chainring coupled to the layshaft, such that the chainring rotates with the layshaft; and
a shifting system including an actuator configured to urge the segments of the inboard gear of the first gear cluster into and out of the plane of the belt, such that a gear ratio of the gearbox is changeable without displacing the belt out of the plane.
2. The gearbox of claim 1 , wherein the segments of the inboard gear of the first gear cluster are configured to translate axially into and out of the plane of the belt.
3. The gearbox of claim 1 , wherein the segments of the inboard gear of the first gear cluster are configured to pivot into and out of the plane of the belt.
4. The gearbox of claim 3 , wherein the outboard gear of the first gear cluster includes a plurality of pivotable outboard segments arranged in pairs with the inboard segments, each pair of outboard and inboard segments being mounted to a common hinge, such that pivoting the inboard segment of the pair out of the plane automatically pivots the outboard segment of the pair into the plane.
5. The gearbox of claim 3 , wherein each of the segments of the inboard gear has a respective pin protruding transversely from an inboard face; and
wherein the actuator of the shifting system includes a shifting wedge transitionable between:
(a) a first configuration, in which a first ramped face of the wedge is in line with the pin of each segment of the inboard gear of the first gear cluster when the segment is out of the plane, such that rotating the pin into the first ramped face is configured to urge the segment into the plane, and
(b) a second configuration, in which a second ramped face of the wedge is in line with the pin of each segment of the inboard gear of the first gear cluster when the segment is in the plane such that rotating the pins into the second ramped face is configured to urge the segment out of the plane.
6. The gearbox of claim 3 , wherein a respective inboard gear of the second gear cluster includes a plurality of pivotable segments.
7. The gearbox of claim 6 , the actuator of the shifting system further comprising a second shifting wedge configured to pivot the segments of the inboard gear of the second gear cluster.
8. The gearbox of claim 1 , wherein an outboard gear of the first gear cluster is nestable with the inboard gear.
9. The gearbox of claim 8 , wherein the outboard gear is a non-segmented gear.
10. A gearbox for a vehicle, the gearbox comprising:
a drive spindle;
a first gear cluster coaxially fastened to the spindle such that the first gear cluster rotates with the spindle, wherein an inboard gear of the first gear cluster includes a plurality of pivotable inboard segments, each of which has a respective pin protruding transversely from an inboard face;
a second gear cluster having one or more gears coaxially fastened to a layshaft spaced from and parallel to the spindle, such that the layshaft rotates with the second gear cluster;
a continuous first belt coupling the first gear cluster to the second gear cluster, such that the first gear cluster drives the second gear cluster and the first belt defines a first plane, wherein the segments of the inboard gear of the first gear cluster are each pivotable into and out of the first plane;
a third gear cluster having one or more gears coaxially fastened to the layshaft and spaced from the second gear cluster, such that the third gear cluster rotates with the layshaft;
a fourth gear cluster having one or more gears coupled to a sleeve coaxially mounted over the spindle such that the sleeve rotates independently of the spindle;
a continuous second belt coupling the third gear cluster to the second gear cluster, such that the third gear cluster drives the fourth gear cluster and the second belt defines a second plane parallel to the first plane;
a chainring fastened to the sleeve, such that the chainring rotates with the fourth gear cluster; and
a shifting system including a first shifting wedge transitionable between:
(a) a first configuration, in which a first ramped face of the wedge is in line with the pin of each segment of the inboard gear of the first gear cluster when the segment is out of the first plane, such that rotating the pin into the first ramped face is configured to urge the segment into the first plane, and
(b) a second configuration, in which a second ramped face of the wedge is in line with the pin of each segment of the inboard gear of the first gear cluster when the segment is in the first plane such that rotating the pins into the second ramped face is configured to urge the segment out of the first plane.
11. The gearbox of claim 10 , wherein the first gear cluster, second gear cluster, first belt, third gear cluster, fourth gear cluster, and second belt are enclosed in a housing.
12. The gearbox of claim 10 , wherein an outboard gear of the first gear cluster is nested within the inboard gear, such that the outboard gear is in line with the first plane.
13. The gearbox of claim 12 , wherein the outboard gear is a non-segmented gear.
14. The gearbox of claim 10 , wherein an outboard gear of the first gear cluster includes a plurality of pivotable outboard segments arranged in pairs with the inboard segments, each pair of outboard and inboard segments being mounted to a common hinge, such that pivoting the inboard segment of the pair out of the first plane automatically pivots the outboard segment of the pair into the first plane.
15. The gearbox of claim 10 , wherein the drive spindle is coupled to a crankset configured to rotate the spindle.
16. The gearbox of claim 10 , wherein the drive spindle is coupled to an electric motor configured to rotate the spindle.
17. The gearbox of claim 10 , wherein an inboard gear of the second gear cluster includes a plurality of pivotable segments, each of which has a respective pin protruding transversely from an inboard face.
18. The gearbox of claim 17 , the shifting system further comprising a second shifting wedge configured to pivot the segments of the inboard gear of the second gear cluster.
19. A gearbox for a vehicle, the gearbox comprising:
a drive spindle;
a first gear cluster coaxially fastened to the spindle such that the first gear cluster rotates with the spindle, the first gear cluster including an outboard gear and an inboard gear, wherein the inboard gear is physically divided into a plurality of segments;
a second gear cluster having one or more gears coaxially fastened to a layshaft spaced from and parallel to the spindle, such that the layshaft rotates with the second gear cluster;
a continuous first belt coupling the first gear cluster to the second gear cluster, such that the first gear cluster drives the second gear cluster and the first belt defines a first plane, wherein the segments of the inboard gear of the first gear cluster are each movable into and out of the first plane;
a third gear cluster having one or more gears coaxially fastened to the layshaft and spaced from the second gear cluster, such that the third gear cluster rotates with the layshaft;
a fourth gear cluster having one or more gears coupled to a sleeve coaxially mounted over the spindle such that the sleeve rotates independently of the spindle;
a continuous second belt coupling the third gear cluster to the second gear cluster, such that the third gear cluster drives the fourth gear cluster;
a chainring fastened to the sleeve, such that the chainring rotates with the fourth gear cluster; and
a shifting system including an actuator configured to urge the segments of the inboard gear of the first gear cluster into and out of the first plane, such that a gear ratio of the gearbox is changeable without displacing the first belt out of the first plane.
20. The gearbox of claim 19 , wherein the segments of the inboard gear of the first gear cluster are configured to translate into and out of the first plane along the spindle.
21. The gearbox of claim 19 , wherein the segments of the inboard gear of the first gear cluster are configured to pivot into and out of the first plane.
22. The gearbox of claim 21 , wherein the outboard gear of the first gear cluster includes a plurality of pivotable outboard segments arranged in pairs with the inboard segments, each pair of outboard and inboard segments being mounted to a common hinge, such that pivoting the inboard segment of the pair out of the first plane automatically pivots the outboard segment of the pair into the first plane.
23. The gearbox of claim 21 , wherein each of the segments of the inboard gear has a respective pin protruding transversely from an inboard face; and
the actuator of the shifting system includes a shifting wedge transitionable between:
(a) a first configuration, in which a first ramped face of the wedge is in line with the pin of each segment of the inboard gear of the first gear cluster when the segment is out of the first plane, such that rotating the pin into the first ramped face is configured to urge the segment into the first plane, and
(b) a second configuration, in which a second ramped face of the wedge is in line with the pin of each segment of the inboard gear of the first gear cluster when the segment is in the first plane such that rotating the pins into the second ramped face is configured to urge the segment out of the first plane.
24. The gearbox of claim 21 , wherein a respective inboard gear of each of the second, third, and fourth gear clusters includes a plurality of pivotable segments.
25. The gearbox of claim 24 , the actuator of the shifting system further comprising a second shifting wedge configured to pivot the segments of the inboard gear of the second gear cluster.
26. The gearbox of claim 19 , wherein an outboard gear of the first gear cluster is nestable with the inboard gear, and the outboard gear is a non-segmented gear.