Shoe having an external chassis

An athletic shoe including a upper, a support member or "chassis" attached to the underside of the upper, and sole elements attached to the bottom of the support member. The support member provides support for the foot, and thereby permits use of spaced apart sole elements rather than a full midsole and a full outsole. In addition, the support member can be tailored to provide the optimum stiffness for a particular activity or user.

BACKGROUND OF THE INVENTION 
This invention relates generally to shoes, and more particularly to shoes 
wherein light weight and the ability to tailor the stiffness and flexure 
of the shoe is an important consideration. 
Shoes encounter tremendous forces during running or sports. Over the years, 
efforts have been made to reduce the resultant stresses on the feet and 
legs. one advance in this area has been the incorporation of cushioning 
material in the shoe sole to cushion the foot as the shoe strikes the 
ground. This cushioning material is typically formed into a layer called 
the "midsole" which is interposed between the ground-engaging "outsole" 
and the shoe upper. The cushioning midsole, which should also flex with 
the foot, is typically made of ethyl-vinyl-acetate (EVA) or polyurethane 
(PU), although other resilient, cushioning materials could be used. 
While the cushioning provided by a midsole is an advantage, its added 
weight hinders the performance of athletic shoes (particularly running 
shoes), which must be as light as possible. The problem of added weight 
from the midsole is recognized in U.S. Pat. No. 5,319,866 issued to Foley 
et al. Foley et al. attempts to solve the problem by substituting an arch 
support in place of the midsole and outsole underlying the arch area of 
the foot. 
The use of a midsole between the outsole and the upper also positions the 
foot higher above the ground, creating a less stable platform for the 
foot. This problem is addressed to some degree in U.S. Pat. No. 4,542,598 
issued to Misevich et al. Misevich teaches use of a heel plate between two 
heel midsole layers to support and cushion the heel, and a forefoot board 
inside the upper over a forefoot midsole layer to support and cushion the 
forefoot. As in Foley, Misevich eliminates the midsole beneath the arch, 
thereby saving some weight. Unlike Foley, however, Misevich does not 
provide any additional structure to support the arch. 
The negative effects of the impact to the feet and legs can be amplified if 
the shoes are not properly shaped and tuned to the particular sport, and 
to the individual's foot. Mass-produced athletic shoes come in standard 
sizes and shapes, and usually include an arch support designed to fit a 
"standard" foot. Prior art shoes, such as those typified by Foley and 
Misevich, include no provision for tailoring the shoe to fit an individual 
foot, except for the use of orthotics. Orthotics are well-known in the 
art, and are exemplified by U.S. Pat. No. 4,803,747 issued to Brown. 
Orthotics, however useful, represent additional, undesirable weight, and 
also stiffen the shoe and otherwise compromise its performance. 
Accordingly, a need remains for a light-weight shoe that minimizes the 
material in the sole, adequately supports the foot, and which can be 
readily customized for an individual's foot or for a particular activity. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of the invention to provide a shoe, in 
particular an athletic shoe, which can be customized to support the foot 
in accordance with requirements of a particular sport or activity. 
It is another object of the invention to eliminate the need for an outsole 
and midsole which span substantially the entire length of the shoe. 
A shoe according to the invention includes an upper, a chassis, or support 
member, attached to the underside of the upper to support the foot, and 
one or more ground-engaging sole elements affixed to the bottom of the 
chassis at discrete locations. Portions of the chassis are left exposed 
and unsupported by the sole elements. The weight of the shoe is thereby 
minimized because the full-length midsole and outsole have been replaced 
by the discrete sole elements. 
The structural chassis may be contoured to conform to the underside of the 
foot. In one embodiment, the structural chassis has one or more notches or 
slots in locations selected to permit a desired flexure of the foot. The 
length and width of the notches can be varied to vary the shoe's 
flexibility. Alternatively, the structural chassis can be without flexure 
notches, and rely instead on differing thicknesses of materials to vary 
its flexibility in different areas of the shoe. 
A shoe according to the present invention utilizes a single structure for 
altering the support and flex of the shoe, thereby overcoming the 
disadvantage in the prior art that requires multiple elements to be 
modified to achieve the same result. 
The foregoing and other objects, features and advantages of the invention 
will become more readily apparent from the following detailed description 
of a preferred embodiment of the invention which proceeds with reference 
to the accompanying drawings.

DETAILED DESCRIPTION 
A right shoe 10 according to the invention is shown in FIGS. 1-3. A 
corresponding left shoe is a mirror image of the right shoe and is 
therefore not described further. The shoe includes an upper 12 that is 
designed to receive a foot. The upper 12 can be made of any number of 
materials as is known in the art including mesh and/or leather, and is 
preferably of a moccasin-type construction. An advantage of the present 
invention is that since structural support for the foot is provided by the 
external chassis described below, the upper need not do so, and its weight 
can be minimized. In the embodiment shown in FIGS. 1 and 3, a conventional 
lacing system incorporating holes in the upper is used, although other 
lacing arrangements could be used. The upper further may also include 
features such as a foam-filled ankle collar 13 surrounding the ankle 
opening for added comfort. The description of the upper 12 is by way of 
illustration only; numerous alternative upper designs will work equally 
well. 
Mounted on the bottom of upper 12 is an external chassis 14, which 
underlies and supports the foot. Sole elements 16, 18, 20, 22, and 24 
underlie chassis 14, and in the preferred embodiment, are attached thereto 
by an adhesive. 
The design of chassis 14 is based on the structure and bio-mechanics of the 
human foot. A top plan view of a right human foot skeleton is shown in 
FIG. 5. The foot is attached to the leg (not shown) by the talus or 
anklebone 28. Positioned below and rearwardly of the talus 28 is the 
calcaneus 30 (i.e., the heel bone). The navicular 32 and the cuboid 34 are 
positioned below and forward of the talus 28. Three cuneiform bones 36 
extend forwardly from the navicular 32. Extending forwardly from the 
cuneiform bones 36 and from the cuboid 34 are the five metatarsals 38, 
which are numbered a through e from left to right in FIG. 5 (i.e., from 
big toe to little toe). Forwardly of each metatarsal bone is a respective 
phalange 40 that forms the toe. 
Between each metatarsal and its respective phalange is a metatarsal 
phalangeal (MTP) joint. Thus, there are five MTP joints in all: a first 
MTP joint 42, a second MTP joint 44, a third MTP joint 46, a fourth MTP 
joint 48, and a fifth MTP joint 50. These MTP joints can be used to define 
two axes about which the foot pushes off during certain push-off 
movements. A lateral push-off axis A.sub.2 is defined by a line running 
generally through the third (46), fourth (48), and fifth (50) MTP joints. 
The lateral push-off axis is used for push-offs towards the lateral side. 
Turning now to FIG. 2, chassis 14 is designed to accommodate the natural 
flexing of the foot about the lateral push-off axes. 
In the preferred embodiment, chassis 14 is shaped to underlie and support 
the entire foot. In an alternative embodiment, the chassis underlies the 
arch and the forward portion of the foot, a heel-supporting sole element 
is attached directly to the upper. The chassis is preferably made of a 
relatively stiff, resilient material, such as plastic, fiberglass, or a 
carbon fiber-containing material for high-performance applications. The 
embodiment shown in FIGS. 1-3 includes an arch support flange 52, the size 
and shape of which can be varied as required for different foot types and 
for different sports. Notches 56 and 58 at the base of arch support flange 
52 provide a predetermined amount of torsional flexure in the middle part 
of the chassis and shoe. The length and/or width of notches 56 and 58 can 
be varied as well to provide nearly any amount of torsional rigidity to 
the shoe. Notches 64 and 66 formed on opposite sides of the chassis along 
axis A.sub.2 ', which underlies the lateral push-off axis (A.sub.2) of the 
foot. The length and/or width of these two notches can also be varied to 
produce the desired stiffness and/or flexibility of the shoe about the 
lateral axis. 
In the embodiment shown in FIG. 1, slots 70, 71 and hole 72 are formed in 
the heel portion of the chassis to provide flexibility in this region. 
Additional slots can be formed within the heel region if desired, and as 
with the other notches described above, the length and/or width can be 
modified. Chassis 14 also includes medial and lateral heel flanges 80 and 
82 respectively to center and retain the heel in place. 
The embodiment shown in FIGS. 1-3 includes sole elements 16, 18, 20, 22 and 
24 attached to the bottom surface of chassis 14. As will be appreciated by 
persons skilled in the art however, more or fewer sole elements of 
different configurations may be used. Sole elements may be positioned to 
correspond to one or more ground-engaging anatomical structures of the 
unshod foot. Referring to FIG. 5, these points include, but are not 
limited to, the calcaneus, the head of the first metatarsal, the head of 
the fifth metatarsal, the base of the fifth metatarsal, the head of the 
first distal phalange, and the head of the fifth distal phalange. 
Each sole element provides traction, abrasion resistance and cushioning. 
These functions can be satisfied in many different ways. Any of sole 
elements 16, 18, 20, 22 and 24 can have an outer, abrasion-resistant layer 
19 made from a material such as a durable rubber. The outer layer 19 
encases a cushioning material 96 such as EVA or polyurethane. Other 
embodiments of the sole elements are described further below. In the 
preferred embodiment, each sole element is affixed to the bottom of the 
chassis using conventional adhesives, although the invention is not 
limited thereto. Sole element 24 is affixed to the heel portion where it 
provides traction, and cushions impacts to the calcaneus or heel bone of 
the foot. Element 18 is affixed to the chassis in the region underlying 
the "ball of the foot", and provides traction and cushioning for the first 
metatarsal head. Sole elements 20 and 22 support the fifth metatarsal 
head, and the base of the fifth metatarsal in the lateral midtarsal 
portion of the foot respectively. Sole element 16 is affixed to the 
chassis below the toe region of the upper, and in other embodiments can 
extend forward and upwardly around the front end of upper. Any number of 
different surface ornamentations can be applied to these portions, limited 
only by the creativity and ingenuity of the shoe designer. 
Any of the sole elements 16, 18, 20, 22 and 24 in the preferred embodiment 
include rounded edges as shown at 22a in FIG. 4. This feature is explained 
in greater detail in U.S. Pat. No. 5,317,819 to Ellis, which is hereby 
incorporated by reference. 
In another embodiment, the sole elements are filled with gas, such as air, 
or a visco-elastic material. A yet further embodiment of the sole elements 
is shown in FIGS. 9 and 10. In those figures an individual sole element 
160 is shown, which is preferably mounted on the shoe underneath the 
calcaneus bone, i.e., the heel. As in the embodiment described earlier, 
other similar sole elements can be placed in other load bearing points on 
the shoe corresponding to one or more ground-engaging anatomical 
structures of the unshod foot, including, but not limited to the 
calcaneus, the head of the first metatarsal, the head of the fifth 
metatarsal, the base of the fifth metatarsal, the head of the first distal 
phalange, and the head of the fifth distal phalange. 
Sole element 160 includes a plurality of air or visco-elastic filled 
deformation elements 162, 164, 166 and 168. These deformation elements are 
mounted on a base layer 170. The deformation elements are preferably 
elongate, channels extending generally, radially outward from a common 
origin 176. The channels are formed by sidewalls 172 extending vertically 
upward from the base layer to a top, ground-contacting surface 174 and 
sealed by end-walls to form sealed interior channels 178. These channels 
178 are then filled with a gas, such as air, or a visco-elastic material. 
A plurality of hollow, intermediate ribs 180 can be mounted on the base 
plate between adjacent deformation elements. The deformation elements 
allow the base plate to shift horizontally relative to the 
ground-contacting surface as a result of impact. This shifting reduces the 
impact by increasing the amount of time the load is dissipated over. Other 
embodiments of these deformation elements are described in 
commonly-assigned, copending patent application Ser. No. 08/327,461 filed 
Aug. 16, 1995 entitled "Anisotropic Deformation pad for Footwear," 
incorporated herein by reference. The shoe according to the invention can 
work with any of the embodiments shown therein. 
Having described and illustrated the principles of the invention in a 
preferred embodiment thereof, it should be apparent that the invention can 
be modified in arrangement and detail without departing from such 
principles. For example, the design of the sole elements can be modified 
so that different portions of the upper are exposed than those shown 
above. An example of such an alternative design is shown in FIG. 11. In 
that design the sole elements include a toe element 140, a forefoot 
element 146, and a heel element 148. Two additional forefoot elements 142 
and 144 are disposed between the toe portion and the forefoot portion. The 
lateral element 144 is integrally formed with the main forefoot portion 
146 while the medial forefoot element 142 is a separately formed element. 
These elements are arranged so as to create a flex-groove therebetween as 
described further above. The heel portion 148 also includes a heel flex 
groove 150. Unlike the forefoot flex groove, however, the heel flex groove 
150 does not necessarily expose the upper. Instead the sole element is 
grooved in this area so as to provide a desired amount of stiffness and/or 
flexibility in heel area. 
We claim all modifications and variation coming within the spirit and scope 
of the following claims.