Seal for a joint or juncture – Seal between relatively movable parts – Circumferential contact seal for other than piston
Reexamination Certificate
1999-03-30
2001-12-04
Browne, Lynne H. (Department: 3626)
Seal for a joint or juncture
Seal between relatively movable parts
Circumferential contact seal for other than piston
C277S551000, C277S572000, C384S486000, C475S285000, C475S297000
Reexamination Certificate
active
06325386
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed internal bicycle hub transmissions and, more particularly, to an internal hub transmission which uses a sealing assembly that rotates with the hub shell.
Bicycles, particularly recreational bicycles referred to as city cruisers, are inexpensive and are easy to ride, and are thus widely used to commute to work or school or for shopping. With this type of recreational bicycle, an internal hub transmission is sometimes mounted at the rear wheel in order to ride at high speeds over flat terrain or to ride uphill with minimal exertion.
An internal hub transmission generally comprises a hub axle that is fixed to the bicycle frame; a hub shell that is able to rotate around the hub axle; a driving member for receiving a driving force from the drive chain; a planet gear mechanism that is housed in the hub shell for transmitting the driving force from the driving member to the hub shell through a plurality of transmission paths; and a clutch mechanism for selecting among the plurality of transmission paths. The clutch mechanism has a clutch member for switching the drive transmission path by moving in the direction of the hub axis, and a push rod that presses the clutch member.
Because the driving member and hub shell are capable of rotation relative to each other, there is a space between the two which creates a risk that water, dirt and other contaminants may enter the inside of the hub shell and adversely affect the operation of the planet gear mechanism and other components. Some internal hub transmissions use a labyrinth-type sealing mechanism to inhibit entry of contaminants into the hub shell. However, since such a system relies on staggered barrier walls with spaces between the barrier walls, there is still a risk that contaminants can migrate between the barrier walls and enter the inside of the hub shell, especially if the hub is immersed in water. Other internal transmission hubs use a rubber seal mounted to an inner peripheral surface of an annular metal ring which, in turn, is press-fit onto the inner peripheral surface of the hub shell. While such a sealing mechanism is effective, the rubber seal inevitably becomes worn as a result of the sliding contact with the driving member as the hub rotates relative to the driving member. Because the annular ring containing the rubber seal is press-fit onto the inner peripheral surface of the hub shell, removal of the old seal and installation of a new seal is very difficult. Thus, it is desirable to have a sealing system with the sealing characteristics of a rubber seal but which can be removed and replaced easily.
SUMMARY OF THE INVENTION
The present invention is directed to a seal for a bicycle hub transmission that effectively prevents entry of contaminants into the hub and also allows easy removal and replacement of the seal. In one embodiment of the present invention, a seal for a bicycle transmission includes an annular housing and an annular seal member. The housing includes a side wall that defines a plurality of circumferentially disposed slots. The seal member is retained to the housing and extends radially inwardly. The seal member is formed from a resilient material, and the housing is formed from a material that is more rigid than the seal member.
When the present invention is applied to a bicycle hub, the bicycle hub includes a hub shell that rotates around a hub axis, wherein the hub shell has at least one of a hub coupling projection and a hub coupling groove; an inner member disposed coaxially with the hub shell; a transmission for communicating a driving force to the hub shell through a plurality of transmission paths; and a seal. The seal includes an annular housing and a seal member. The housing includes a side wall having at least one of a side wall coupling projection and a side wall coupling groove engaging the at least one of the hub coupling groove or hub coupling projection, respectively. The seal member is retained to the housing, extends radially inwardly and contacts the inner member. The inner member may be a bearing cone or a driving member for providing the driving force to the hub shell.
In a more specific embodiment of a bicycle hub that incorporates the present invention, the at least one of the hub coupling projection and hub coupling groove is a hub coupling groove disposed on an outer peripheral surface of the hub shell, the at least one of the side wall coupling projection and side wall coupling groove is a side wall coupling projection disposed on an inner peripheral surface of the side wall and engaging the hub coupling groove, and the side wall defines a plurality of circumferentially disposed slots extending through an end of the side wall that is coupled to the hub shell. This structure makes it very easy to install and remove the seal from the hub shell, especially when the housing is formed from metal and the seal member is formed from rubber, since the slots allow the end of the housing to be spread apart from the hub shell.
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Browne Lynne H.
Deland James A.
Patel Vishal
Shimano Inc.
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