Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to devices that comprise
rims which are interconnected to hubs by a plurality of arms.
The invention described herein possessesparticular utility when
applied to such devices used as automobile steering wheels which
will both transmit torque between the rim and hub and will absorb
rim impact loads by an energy absorbing deformation occurring
in one or more arms. However, the invention is not limited to
use in such devices and may in fact be applied to devices such
as gears and flywheels which have a hub and a rim interconnected
by at least one spoke.
In the case of automobiles, the steering wheel comprises
a rim connected to the hub by one, two or three arms. The steer-
ing wheel generally has its axis of rotation mounted at an angle
to the horizontal so that the bottom of the rim is its rearward-
most portion. During a collision, the driver of the vehicle may
be thrown against the steering wheel, and the more rigid the steer-
ing wheel, the greater the impact force which will be exerted
upon the body of the driver. Therefore it is desirable for the
steering wheel or the shaft upon which the steering wheel is mount-
ed to absorb this impact energy thereby reducing the injuriessustained by the driver.
It is an object of the present invention to provide
a new and improved steering wheel which in addition to transmit-
ting normal torque loads repeatedly will absorb impact loads of
the type described without recoil.
According to the invention, then, there is provided
a torque transmitting article comprising at least one arm connect-
ing a rim to a hub, wherein the arm comprises a multiplicity of
substantially parallel filaments extending longitudinally of the
arm and reinforced and maintained in the parallel alignment by
a matrix of hardened binder of controlled shearability.
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According to a further aspect of the present invention,
there is also provided a one-piece steering wheel having a rim,
a center hub for mounting the steering wheel upon a steering shaft,
and at least one spoke connecting the hub and the rim, the rim,
hub and spoke comprising a continuous hardened resinous matrix
material of controlled shearability reinforced with continuously
wound filamentary material, the filamentary material extending
circumferentially about the rim, longitudinally through the spoke
- . and circumferentially about the hub and comprising a multiplicity
of substantially parallel filaments maintained in the parallel
alignment by the hardened matrix material.
According to yet another aspect of the present inven-
tion, there is also provided a method of making a torque trans-
mitting article having a rim connected by an arm to a hub, com-
prising the steps of arranging a multiplicity of parallel fila-
ments in the longitudinal direction of the arm, impregnating the
filaments with a hardenable binder of controlled shearability
to reinforce and mai~tain the filaments in the parallel align-
ment, and molding the arm in one piece with the rim and the hub.
According to yet another aspect of the present invention,
there is provided a method of making a steering wheel armature
having a hub and rim connected by arms comprising, forming a first
preform by filament winding a continuous strand into a hoop to
form part of the rim, forming a second preform by filament wind-
ing a contlnuous strand into a second hoop having a periphery
sufficient to extend around the hub, outwardly therefrom along
first and second arms and over the portion of the rim between
the arms, forming a third preform by filament winding a conti-
nuous strand into a third hoop having a periphery sufficient to
extend around the hub, outwardly along second and third arms and
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er the portion of the rim connecting the second and third arms,
the strands each comprising a multiplicity of parallel fibers,
placing the second preform adjacent the first preform with its
portion connecting the first and second arms superimposed on
a portion of the first preform, placing the third preform adjacent
the first and second preforms with its second arm portion adjacent
the second arm portion of the second preform and the portion con-
necting its arms superimposed on a portion of the first preform,
causing all preforms to contain a hardenable binder, and bonding
the first, second, and third preforms together to produce the
armature.
The invention will become more readily apparent to
those skilled in the art to which the invention relates from the
following description of several preferred embodiments described
with reference to the accompanying drawings forming a part of
this specification.
Figure 1 is a perspective view of a cured, composite
steering wheel embodying the present invention;
Figure 2 is a sectional view through the hub and oppo-
site arms of the steering wheel shown in Figure l;
Figure 3 is a plan view of a segmented mold on whichfilaments are wound for producing the steering wheel shown in
Figures 1 and 2. The mold contains a groove around its periphery
and three grooves extending therefrom obliquely upwardly to a
hub which forms the remainder of the armature;
Figure 4 is a vertical sectional view taken approxi-
mately on the line 4-4 of Figure 3;
Figures 5a, 5b and 5c show in schematic form, vàrious
patterns that can be used for winding strand into the mold to
produce the armature;
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Figure 6 is a schematic diagram depicting a method for
impregnating a strand with binder, and winding the binder impreg-
nated strand into the mold; and
Figures 7a, 7b and 7c schematically depict a process
wherein: a preform is made by filament winding a preform in one
mold, the preform is transferred to a second mold where it is
impregnated with resin using pressure and vacuum, and the mold
is heated to harden the resin.
While the invention may be otherwise embodied, it i5
first described as embodied in a steering wheel for an automo-
tive vehicle.
There is described hereinafter a steering wheel which
will disrupt when overloaded by crack propagation longitudinally
of an arm without breaking the top and bottom surfaces (filaments)
of the arm. The disruption preferably occurs close to the center
of the arm to in effect produce two half thicknesses of arm which
in turn are more flexible and can yield through a greater dis-
tance. This is accomplished by providing the arms with a rein-
forcement comprising a large number of high strength parallel
filaments, which are preferably anchored at one end to the rim
and the other end to the hub. The filaments are held in parallel
alignment by a hardened binder of a controlled shearability in-
tended to permit controlled inter-laminar delamination between
the filaments when the rim is impacted or otherwise overloaded.
The filament resin composite of the arms being of very high
strength and anchored at both ends hold the rim to the hub allow-
ing progressive transmission of load by the rim to other arms.
Suitable filaments may be organic, inoryanic, or metal-
lic. Organic filaments include polyesters, nylon, aramid, poly-
propylene, cotton, acrylics, etc. Inorganic filaments include
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,raphite, boron, glass, etc: metallic fibers include aluminum,
steel, etc. Mixtures of the above fibers may be used in the com-
posite steerin~ wheel construction. Because of availability and
relative inexpensiveness, commercially available strands of glass
filaments are the preferred reinforcement.
Suitable binders may likewise be organic or inorganic.
Organic binders will include the polyester resins, epoxy resins,
aldehyde condensate resins, polyamide resins, etc. with or with-
out inert fillers. Suitable inorganic binders will include the
mag-oxy cements. The binder system is preferably tailored to
give a desired bond to the fibers and a desired inter laminar
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shear strength to the arm.
The anchorage of the longitudinal arm fibers between
the rim and hub can be accomplishe,d in a number of ways, however
it is preferable for the fiber strands to extend uninterrupted-
ly around an appreciable portion of the rim and hub.
A typical frame, or armature, of a steering wheel
embodying the present invention is shown in Figures 1 and 2
of the drawings. One method of producing such frames, or arma-
tures, is shown in Figures 3 through 6 and comprises a series
of spools 11 bearing filamentary reinforcement such as con
tinuous glass filaments 12. The filaments are led through a
spacing arrangement 13 and into an impregnation tank 14 contain-
ing a suitable resin 15 such as polyester, vinyl-ester, epoxy,
etc.; the filaments are thereby impregnated with resin. The
filaments are then passed through a feed eye 16 and laid into,
or onto a mold 17 along its periphery 18 and channels 19. Rota-
tion of the mold either alone or in coordination with the feed
eye will produce a build up of filaments to a desired thick-
ness. The lay down pattern may be varied at will to establish
any desired paths for the filament and any desired volume ratio
of the hub, arms or rim. Typical winding patterns which are
shown in Figures 5a and 5c can produce a two spoke steering
wheel; the winding pattern of Figure 5b will produce a single
spoke wheel. One example of a suitable mold 21 is shown in
Figures 3 and 4 and comprises split blocks 22 and 23, block
23 providing a plurality of threadably removable segments 24.
The mold 21 is mounted on a shaft 25, one end of the shaft pas-
sing through a metal or plastic hub 26 and being secured therein
by a bolt 27. At its other end, the shaft is threaded into
or spline connected with a winding machine spindle 28 so that
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block 22 will bear against spindle shoulder 29. This arrange-
ment permits the shaft 25 to be varied in length and thus alter
the angle of th~ arms relative to the hub 26 or depth of the
steering wheel. An outer, peripheral channel 30 is defined
by the mold 21 and a plurality of inclined channels 32, 33 and
34 are provided by the split block 22. However, it is obviously
within the scope of the invention to provide a rim forming
channel or cavity on the surface of split block 22 located in-
terior from the periphery. Additionally, the rim forming
channel may have a multi-cornered configuration to bind the
filaments at the corners during the initial filament lay-down.
This technique enables the filament to be wound more tightly
into the channel to achieve a pre-stressed effect.
In operation, continuous filaments such as glass
fibers, graphite, aramid, etc., are fed from the spools 11,
and advanced through the impregnation tank 14 and wound in a
continuous manner around the peripheral channel 30, and along
channels 32, 33 and 34. In the process, the filaments are also
wound around the hub 26 so that the hub becomes incorporated
by the windings into the steering wheel structure.
The filaments may be applied by movement of the feed
eye 16 while the mold 21 remains motionless or the mold may
be rotated while the feed eye arm is motionless; this latter
mode is useful when applying a filament build up to the peri-
pheral channel 30.
Following completion of the desired amount of fila-
ment build the mold 21 is simply removed from the spindle 28
by pulling out or unscrewing the shaft 25 to which the mold
is attached. The mold may then be placed in an oven and sub-
jected to heat and pressure to produce a cured resin-filament
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steeriny wheel composite. Following the cure treatment, the
removable segments 24 and bolt 27 are unscrewed or loosened
and the cured steering wheel 35 and hub 26 are removed from
the mold 21.
Figures 7a, 7b and 7c illustrate another method of
producing the filamentary wound steering wheel. The filaments
are deposited or applied into a mold 40 (Figure 7a) essentially
free of resin, the filaments being held together by a light
binder which is compatible with, or soluble in, a suitable matrix
resin. This produces a preform 41 as shown in Figure 7b; the
preform is then transferred to a mold, as shown in Figure 7c,
in which the matrix resin is introduced under vacuum, pressure,
or a combination thereof thereby impregnating the preform. The
mold containing the resin-impregnated preform is then cured.
Figure 1 shows the cured steering wheel 35 comprising
a rim 36, integrally connected spokes 37, a hub support 38,
and a metallic hub 39 wound within the hub support. The
structure may be used either as a steering wheel without any
further processing of significance, or it may be used as the
primary load-bearing armature to be subsequently covered with
materials chosen on the basis of aesthetics, color, or other
considerations.
Figure 2 shows the portion of a typical steering wheel
structure 45 of filamentary material impregnated with a matrix
resin 46 that has been wound around a hub 47 and cured. A
splined central channel 48 is provided by the hub, and outer
washer shaped portions 49 are disposed peripherally of the hub.
Since it is embedded within the cured matrix resin, a strong
mechanical bond is formed between the resin and hub, particularly
at the washers 49. Additionally, bonding forces due to ad-
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hesion, and con~raction forces due to phase change, combinewith the mechanlcal bond to form an excellent, long term bond
between the hub and steering wheel.
As previously indicated, still other methods exist
for producing the orientation of fibers desired by the present
invention. One of the simplest ways of making parallel group-
ings of glass fibers is achieved by filament winding a strand
on a revolving drum to produce either a hoop of predetermined
bandwidth, or a continuous cylinder. Part of the rim of ap-
plicant's armature, for example, could be made by filament wind-
ing a strand into a hoop of the desired rim dimension. Arms
can be attached to the rim and the hub by making suitable seg-
mented preforms from filament wound hoops the periphery of which
correspond in length to that of two arms, plus the peripheral
portion of the rim between the two arms, plus a turn around
the hub. These preforms can be twisted into a figure eight
having a large and a small diameter loop. These figure eight
preforms are then forced endwise into a suitable mold with the
small diameter loop extending around the hub and the large dia-
meter loop extending up the adjacent sides of two adjacent armsand around the interconnecting rim portion. Three such preforms
may be placed into a mold on top of a circular hoop forming
the top portion of the rim to produce an armature having three
arms. The preforms are of course impregnated with a binder
forming material and upon curing of the binder the preforms
are integrated into a rigid armature having substantially the
same fiber configuration and physical properties as the armature
produced by the continuous winding process. In both the con-
tinuous winding process and the process utilizing a plurality
of preforms, the fibers are connected to the rim and to the
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hub by radil leaving a small triangular hollow in the center.
The radii that are thus naturally produced increase the section
modulus of the arms at their juncture with the rim and hub and
prevent stress concentration at these points.
In both of the embodiments above described, the rim
36 may be displaced axially approximately six inches from the
hub 39, so that an object impacting on the rim will cause one
of the arms to yield. In the normal straight ahead position
of the steering wheel, one of the arms will be at the bottom
of the steering wheel. As this arm is being deformed under
impact loading rim 36 transfers increasing portions of the impact
load to the other arms of the armatùre - two of which will nor-
mally be horizontal. Thus a sequential transfer of the impact
load to various arms of the armature results.
In the preferred construction, the arms fail while
the rim remains intact. Failure of the arms is caused by inter-
laminar shear near the center of the arms. These disruptions
preferably start in the center third of the arm and progressively
increase in length along the arm. The disruptions produce longi-
tudinal cleavages between the resin and the fibers leaving thefibers intact. As cleavage increases in length, the arm be-
comes more flexible causing further deflection and in turn fur-
ther cleavage - all during which a sustained resistance to the
impact load is provided. The binder between the fibers can,
of course, be designed to provide any desired shear strength
by modifying the amount of inert fillers used or altering the
composition of the resin or both.
While embodiments of the invention have been described
in considerable detail, the invention is not limited to the
particular embodiments shown and described and includes all
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novel adaptations, modi~ications, and arrangements thereof which
come within the practice of those skilled in the art to which
the invention relates and which Eall within the purview of the
following claims.
As mentioned in the preamble of the disclosure the
methods described above and equally applicable to devices other
than vehicle steering wheels. For example a flywheel may be
produced in which a hub and a rim are connected by spokes for-
med from generally parallel fibers. In this case the spokes
may not be dished in the manner shown with respect to the steer-
ing wheel. The spokes may be bonded to a heavy metal rim during
formation of the spokes or an additional rim could be attached
after the basic form has been produced. Naturally the shear
characteristics of the spokes will not be utilized in such an
application although the benefits such as economy of manufacture
may still be achieved.
A further example of the utilization of the methods
discussed above is the production of a spoked gear wheel. In
this case a basic spoked form having a circular rim may be pro-
duced and an additional rim with gear segments formed thereinadded. Alternatively the gear segments could be formed in-
tegrally with the basic form, either by laying the fibers in
such a manner as to define the individual teeth or by curing
the preform in a mold having the shape of the teeth defined
,in the wall thereof. The teeth may be formed by injecting suf-
ficient matrix resin into the mold to form the teeth and bind
the fibers or by placing preformed segments in the mold and
connecting the rim and segments by a matrix binder.
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