Brakes – Vehicle – Velocipede
Reexamination Certificate
1999-04-09
2001-07-24
Oberleitner, Robert J. (Department: 3613)
Brakes
Vehicle
Velocipede
C188S024190, C188S024210
Reexamination Certificate
active
06264008
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to bicycle brake mechanisms, and more particularly to brake mechanisms exhibiting substantially translational motion during brake actuation.
DESCRIPTION OF RELATED ART INCLUDING INFORMATION DISCLOSED UNDER 37 CFR 1.97 AND 37 CFR 1.98
Bicycle brake assemblies commonly employ a pair of cantilevered brake arms that are pivotally mounted to a bicycle frame.
FIG. 1
depicts a typical cantilever brake assembly wherein a brake arm
10
is pivotally attached to a bicycle frame member (not shown) at a pivot
12
and actuated by a cable or hydraulic line at a remote point
14
by a force A. A brake pad carrier
16
is attached to the brake arm
10
at one end and has a brake pad or shoe
18
attached at its other end. Upon rotation of the brake arm
10
in a clockwise direction, the brake pad
18
is swept along an arched path B until the pad contacts a rim
20
. So configured, the brake pad will exhibit “brake dive” during actuation as the contact surface
20
of the brake pad
18
not only rotates but also drops toward the bottom of the rim
20
, resulting in a single point of contact with the rim and reduced braking performance. Under continued use, the pad thickness is reduced thereby exacerbating the brake dive problem and in some cases resulting in a portion of the pad
20
falling below the rim thereby further reducing braking performance.
Maximum braking force is obtained by parallel, straight-line application of the brake pads to the rim as shown in FIG.
2
. Such a “pure parallel-push” brake pad application is exhibited by the piston-type brake assembly described in U.S. Pat. No. 5,775,466 issued to Banyas. Such brake assemblies, however, tend to “chatter” as the piston binds within the housing through which it displaces upon brake pad contact with the rim. Other brake assemblies include brake carriers
16
that are pivotally attached to the brake arm
10
and mechanisms linking the brake carrier
16
to the bicycle frame that ensure that the pad face
20
remains parallel to a contact surface
58
of the rim
20
as the brake arm
10
is actuated. In such “arched parallel-push” systems as shown in
FIG. 3
, the pad
18
may still exhibit some drop, but this can be minimized by designing the brake arm
10
such that the brake pad
18
sweeps along the top of arc B, thereby still providing very powerful braking. U.S. Pat. No. 5,636,716 issued to Sugimoto employs one type of arched parallel-push motion. However, the mechanism used to maintain the brake carrier in the correct attitude in the Sugimoto patent involves a complex 4-bar/4-pin parallelogram linkage that has a substantial amount of inherent tolerance build-up or slop, resulting in brakes “squealing” during actuation.
SUMMARY OF THE INVENTION
It is the object of the invention to provide a parallel-push brake assembly that provides substantially translational motion of the brake pad using a simple mechanism that is relatively free of tolerance build-up.
According to one aspect of the invention, a brake assembly includes a brake arm pivotally connected to a bicycle frame member at a pivot. A brake pad assembly is pivotally connected to the brake arm at an axis spaced from the pivot, the brake pad assembly including a brake pad. Either a cam surface or a follower surface is made a part of the brake pad assembly, while the other of a follower surface or a cam surface is affixed relative to the bicycle frame member. The cam surface and the follower surface are in engagement with each other such that upon actuation of the brake arm to pivot around the pivot, the follower surface tracks along the cammed surface. Preferably, the follower surface and the cam surface translate the arcuate motion of the brake arm to a substantially translational trajectory of the brake pad, although other desired motions of the brake pad can be had upon modification of the shape of the cams or cam followers.
According to another aspect of the invention, the first and second engagement surfaces on the brake pad assembly and as affixed to the bicycle frame member, respectively, are connected together using an interconnect member. This interconnect member can be in rolling engagement with the first and second engagement surfaces. In one embodiment, the interconnect member is a chain, and the first and second engagement surfaces are geared to receive the chain. In another embodiment, the interconnect member is a further gear which engages those geared surfaces. The interaction of the first and second engagement surfaces with the interconnect member modifies the arcuate motion of the brake arm to produce a different motion in the brake pad. In the illustrated embodiment, this brake pad motion is substantially translational, although other paths of the brake pad can be devised by suitable modification of the shapes and locations of the first and second engagement surfaces and the member interconnecting them.
In another embodiment of the invention, the brake pad attachment member is pivotally attached to a slot located in the brake arm, the slot being configured to permit sliding adjustment of the brake pad attachment member in order to tension the flexible interconnect member.
In yet a further embodiment of the invention, a first slot is disposed on a first one of the brake pad attachment member and the urging member. A first pin is disposed on a second one of the brake pad attachment member and the urging member, the pin and the slot being configured such that upon actuation of the brake arm, the pin slides along the first slot, thereby causing the brake pad to be displaced along a predetermined trajectory. The predetermined trajectory can be translational or it can take another predetermined path.
In yet another aspect of the invention, first and second tension-only carrying members are each pivotally connected to the brake pad attachment member and the urging member. The pivotal connections of the tension-only carrying members are disposed on the brake pad attachment member and the urging member, such that upon actuation of the brake arm, the brake pad is displaced along a predetermined trajectory. It is preferred although not required that this predetermined trajectory be translational.
REFERENCES:
patent: 5501301 (1996-03-01), Nishimura
patent: 5636716 (1997-06-01), Sugimoto et al.
patent: 5655630 (1997-08-01), Sugimoto
patent: 5743284 (1998-04-01), Lumpkin
patent: 5775466 (1998-07-01), Banyas et al.
patent: 5913387 (1999-06-01), Yamashita et al.
patent: 5913388 (1999-06-01), Ota et al.
patent: 5960913 (1999-10-01), Kuo
patent: 6089356 (2000-07-01), Ohta et al.
patent: 6109397 (2000-08-01), Chen
Calilung Ryan A.
Cheever John D.
Johnson Michael P.
Jordan Brian T.
Mankotia Sanjeev K.
Milosevic Milan
Oberleitner Robert J.
Perkins Jefferson
Pezzlo Benjamin A.
Piper Marbury Rudnick & Wolfe
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