Planetary gear transmission systems or components – With means to vary drive ratio or disconnect drive – Plural drive ratios other than unity
Patent
1999-04-30
2000-04-11
Marmor, Charles A
Planetary gear transmission systems or components
With means to vary drive ratio or disconnect drive
Plural drive ratios other than unity
475289, 475312, 475340, B62M 1118, F16H 344
Patent
active
060482877
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a multispeed gearshift mechanism of the species recited in the preamble of claim 1.
Multispeed gearshift mechanisms for bicycles, in particular in the form of multispeed gearshift mechanism hubs, are known in many embodiments. Like derailleurs, they are used to provide several selectable gear steps, or respectively gear ratios. Up to now it has been possible to realize up to twelve gear steps with such gears which, as a rule, was accomplished by placing at least two planetary wheel gears, which hereinafter will be called planet gears for short, in series (DE 42 03 509 A1, DE 43 42 347 C1.
To engage the various gears steps, it is customary in connection with such gears to connect at least one sun wheel in a manner fixed against relative rotation selectively with the hub shaft, wherein a connection "fixed against relative rotation" is understood to be such, that the sun wheel is fixedly connected with the hub shaft only in one selected direction of rotation, while in the opposite direction of rotation it can turn on the hub shaft in the manner of a free-wheeling device. Selector ratchets, which engage teeth and can be selectively disengaged from them, are used for creating this state.
In known multispeed gears of the species identified at the outset (EP 0 383 350 B1, DE 41 42 867 A1), the tooth arrangement consists of radially projecting teeth applied to the outer jacket of a hub shaft, while the selector ratchets are pivot levers, which have been resiliently prestressed and are pivotably seated on the sun wheels. To prevent the engagement of the selector ratchets with the tooth arrangement, or to release selector ratchets which are already engaged from this engagement, a selector sleeve, rotatably seated on the hub shaft and provided with locking tongues, is additionally provided. It can be rotated on the hub shaft in such a way that either the dropping of the ratchets into the gaps between the teeth is prevented, or that already dropped selector sleeves are released from engagement by running up on an appropriate inclined surface.
A problem of such shifting devices consists in that they lead to a not inconsiderable increase in diameter and therefore also to an increase in the weight of the gear hub, since all shiftable elements must be arranged within the effective range of the selector sleeve surrounding the hub shaft. Furthermore, the selector sleeve prevents the application of further selector devices, in particular those operating by means of axially displaceable selector slides (DE 42 03 509 A1), so that either the multispeed hub is designed to be large and therefore also heavy, or the entire switch mechanism must be put together from components which are of such small and weak dimensions, that a great susceptibility to failure results.
In contrast to this, it is the object of the invention to design the multispeed gear of the species identified at the outset in such a way that the selector devices do not result in considerable enlargements of the diameter of the gear, but that a large operational dependability is still assured.
The characterizing features of claim 1 are employed to attain this object.
Further advantageous characteristics of the invention ensue from the dependent claims.
The invention will be explained in more detail in what follows by means of an exemplary embodiment in connection with the attached drawings. Shown are in:
FIG. 1, a longitudinal sectional view of a multispeed gear in accordance with the invention,
FIGS. 2 to 4, cross-sectional views of the planetary gears of the gear hub approximately along the lines II--II to IV--IV in FIG. 1 on a slightly enlarged scale,
FIG. 5, a basic sketch of the gear in accordance with FIG. 1,
FIG. 6, a lateral view of a clutch of the multispeed gear in accordance with FIG. 1 on an enlarged scale,
FIGS. 7 and 8, sectional views along the lines VII--VII and VIII--VIII in FIG. 6,
FIG. 9, a section of a hub shaft in accordance with the invention provided with a selector ratchet in an enlarged and drawn apart representation
REFERENCES:
patent: 5078664 (1992-01-01), Nagano
patent: 5855530 (1999-01-01), Huang et al.
patent: 5961416 (1999-10-01), Shoge
Marmor Charles A
Parekh Ankur
Striker Michael J.
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