Machine element or mechanism – Control lever and linkage systems – Elements
Reexamination Certificate
2002-05-16
2003-12-30
Luong, Vinh T. (Department: 3682)
Machine element or mechanism
Control lever and linkage systems
Elements
Reexamination Certificate
active
06668681
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to handlebars and, more particularly, to handlebars with an adjustable dampening mechanism for motorcycles, bicycles, all terrain vehicles, and personal watercrafts.
BACKGROUND OF THE INVENTION
Handlebars for motorcycles generally comprise a single length of low carbon alloy steel tube appropriately bent to provide a central region, bent regions, and respective handgrip regions, the former being clamped at one or two positions to form a connection to the main cycle frame via an intermediate top yoke or stem. To reduce weight, aftermarket handlebars are typically formed from aluminum. For additional strength, it has been conventional to provide a crossbar spanning the central region of the aluminum tube. Alternatively, the handlebar may be strengthened by providing an aluminum tube with a greater external diameter at the central region, wherein the diameter of the aluminum tube is gradually reduced towards the distal ends.
U.S. Pat. No. 4,635,499 discloses a conventional handlebar
10
of the first type. This type of handlebar
10
is commonly used for offroad motorcycles, all terrain vehicles and personal watercrafts. Referring to
FIG. 1
, the handlebar
10
has a central region
12
, two bent regions
14
,
16
, and two handgrip regions
18
,
20
. The diameter of the handlebar
10
is uniform throughout the entire lengthwise dimension. In general, the preferred diameter of conventional handlebars is ⅞ inch because this provides the handgrip regions
18
,
20
with the proper amount of thickness so that a handgrip with a thickness of approximately ⅛ to ¼ inch can be fitted over a portion of each handgrip region
18
,
20
. Although a ⅞ inch diameter tubing
22
is ideal for facilitating a properly sized handgrip for the rider, the tubing
22
does not have sufficient strength to withstand the impact of heavy loads. As such, a crossbar
24
is used to reinforce the tubing
22
and to prevent the tubing
22
from buckling. The crossbar
24
is attached between the two bent regions
14
,
16
and is oriented generally parallel to the central region
12
. When the crossbar
24
is used, a permanent compression set occurs in the bent regions
14
,
16
in the event of an impact. Furthermore, the crossbar
24
provides no added benefit when steering the vehicle because the crossbar
24
reinforces the handlebar
10
in only the vertical direction while providing no reinforcement in the horizontal direction. Another problem with the crossbar
24
is that a permanent compression set may occur in the event of an impact because the attachment points
26
,
28
of the crossbar
24
at the bent regions
14
,
16
act as a stress concentration site. In addition, the crossbar
24
constrains any movement of the tubing
22
that would soften shock loads to the handgrip regions
18
,
20
. The crossbar
24
may further be a safety hazard. In particular, the rider may impact the crossbar during a crash.
In order to resolve some of the problems associated with crossbars, U.S. Pat. No. 5,257,552 discloses an integrally formed unitary hollow tubular handlebar
50
of the latter type wherein the wall thickness is greatest and constant in the central region
52
, smallest and constant at the handgrip regions
54
,
56
, and tapering in the bent regions
58
,
60
as shown in FIG.
2
. This improved handlebar
50
eliminates the need for a crossbar by increasing the diameter and sidewall thickness of the central region
52
of the handlebar
50
, while the reduction in diameter along the bent regions
58
,
60
and handgrip regions
54
,
56
allows the use of standard handgrips. Without the crossbar, the handlebars
50
has a longer unsupported span, thereby providing more cushioning strength and greater steering control. However, the problem with such a configuration is that a custom triple clamp assembly must be used to secure the handlebar
10
to the main frame of the vehicle because the diameter of the central region
52
is greater than the standardized ⅞ inch diameter. As a result, the available selection of triple clamp assemblies is relatively limited and custom units, which are generally costly, may be required. Furthermore, it is substantially more costly to fabricate tapered handlebars than handlebars with uniform tubes.
U.S. Pat. No. 6,182,528 discloses another handlebar configuration which eliminates the need of a crossbar by having a unitary handlebar
100
comprising an inner tubular member
102
of constant diameter and constant wall thickness and an outer tubular sleeve
104
surrounding the inner tubular member
102
as shown in FIG.
3
. Both the inner tubular member
102
and the outer tubular sleeve
104
have a central region
106
, bent regions
108
,
110
, and handgrip regions
112
,
114
. The handgrip regions
112
,
114
of the inner tubular member
102
extend beyond the handgrip regions
112
,
114
of the outer tubular sleeve
104
. The two-layer configuration allows the use of two different materials to provide a stronger, but more notch sensitive material for the inner tubular member
102
and a more ductile but less notch sensitive material with greater fatigue resistant properties for the outer tubular sleeve
104
. This configuration is advantageous in minimizing stress and impact damage at the locations where the handlebar
100
is clamped to the triple clamp assembly. In the manufacturing process, the inner tubular member
102
and the outer tubular sleeve
104
are formed separately from metal tubes. The thickness of the outer tubular sleeve
104
is reduced prior to insertion of the inner tubular member
102
. Thereafter, the outer tubular sleeve
104
and inner tubular member
102
are shaped together by bending in a conventional manner. Although the outer tubular sleeve
104
comprises a ⅞ outer diameter which is compatible with standard triple clamp assemblies, the fabrication costs are relatively high due to the two-layer construction.
In view of the above, it is apparent that there is a need to provide a handlebar which is capable of withstanding large impact loads while being sufficiently flexible to dampen some of the impact loads. However, the preferred dampening characteristics of the handlebar may depend on the particular riding application (i.e. moto-cross, super cross, desert riding, etc.), physical characteristics of the rider (i.e. size, weight, strength, etc.), suspension system of the vehicle (i.e. spring rate of the fork tubes, xxx, etc.), and the personal preference of the rider. This is particularly important for racing purposes where a slight improvement in the performance of the vehicle provides the rider with a competitive advantage. An operator may incur substantial costs to meet these requirements, wherein a number of prototype handlebars may be needed to first determine the appropriate handlebar configuration for a particular rider and track. Since a rider usually operates the vehicle at several tracks, an inventory of handlebars tailored for each or at least some of the tracks may be needed. In addition to the development and inventory costs, preparation of the vehicle for a particular track may include removal and installation of the handlebar. Thus, there is a need to provide a handlebar which is adaptable to various track and rider conditions. There is also a need to provide a handlebar which is lightweight, durable, easy to manufacture, compatible with existing vehicles, and relatively inexpensive.
SUMMARY OF THE INVENTION
In accordance with the present invention, a handlebar is provided with a titanium tubing capable of absorbing impact loads to reduce rider fatigue and enhance control of a vehicle. In particular, the handlebar is configured with a relatively long unsupported span which allows the tubing to react more readily to impact loads by flexing. The handlebar includes a central region having a first end and a second end, a first bent region extending from the first end of the central region, a second bent region extendi
Flum Andrew S.
Mills Patrick
Blakely , Sokoloff, Taylor & Zafman LLP
Luong Vinh T.
Titeq Corporation
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