U.S. patent application number 15/078005 was filed with the patent office on 2017-09-28 for heelless athletic shoe.
The applicant listed for this patent is Etienne Penka. Invention is credited to Etienne Penka.
Application Number | 20170273400 15/078005 |
Document ID | / |
Family ID | 58401501 |
Filed Date | 2017-09-28 |
United States Patent
Application |
20170273400 |
Kind Code |
A1 |
Penka; Etienne |
September 28, 2017 |
HEELLESS ATHLETIC SHOE
Abstract
A grid for selecting an appropriate embodiment of an athletic
shoe having an upper and a multiple part sole forming an interior
volume for receiving an individual's foot. The multiple part sole
comprises an inner sole for engaging the plantar surface of the
foot, a midsole attached to the exterior of the inner sole and
substantially coextensive with the inner sole, and an outer sole
attached to the midsole. The outer sole has a first portion
extending from the toe of the shoe to a position beneath the foot
selected according to the intended use of the shoe, and has a
second contiguous portion extending from the selected position to
the heel of the shoe, the first portion providing a landing surface
for the shoe and the second portion being relatively thin as
compared to the first portion thereby promoting proper posture and
gait of the wearer.
Inventors: |
Penka; Etienne; (Leominster,
MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Penka; Etienne |
Leominster |
MA |
US |
|
|
Family ID: |
58401501 |
Appl. No.: |
15/078005 |
Filed: |
March 23, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A43B 13/187 20130101;
A43B 13/145 20130101; A43B 13/122 20130101; A43B 7/145 20130101;
A43B 7/142 20130101; A43B 7/1445 20130101; A43B 13/04 20130101;
A43B 7/1425 20130101; A43B 7/143 20130101; A43B 13/181 20130101;
A43B 5/00 20130101; A43B 7/1435 20130101; A43B 13/148 20130101 |
International
Class: |
A43B 13/12 20060101
A43B013/12; A43B 13/04 20060101 A43B013/04; A43B 5/00 20060101
A43B005/00; A43B 13/18 20060101 A43B013/18 |
Claims
1. An athletic shoe having an upper including a toe portion, a
midsection and a rear portion and a multiple part sole forming an
interior volume for receiving an individual's foot, the foot
including a plantar surface and an internal skeletal structure
including a big toe defining a proximal end of the shoe and a
medial arch, said multiple part sole comprising: A. an inner sole
for engaging the plantar surface; B. a midsole having an inner
surface attached to the exterior of said inner sole to be
substantially coextensive with said inner sole, said midsole having
an outer surface; C. an outer sole attached to the outer surface of
said midsole intermediate the inner and outer soles, said outer
sole having a first portion extending from the proximal end of the
shoe to a position being selected according to the intended use of
the shoe and the characteristics of the wearer, said outer sole
having a second contiguous portion extending from the selected
position to the rear portion of the shoe, said first portion
providing a landing surface for the shoe and said second portion
being relatively thin as compared to said first portion thereby to
help prevent injuries to the wearer during a given activity and
promote proper gait during movement.
2. A shoe according to claim 1 in which said first portion of said
outer sole extends from the proximal end of the shoe to a position
beneath the apex of the Calcaneum bone about 90% of the length of
the shoe rearward from the toe of the shoe.
3. A shoe according to claim 1 in which said first portion of said
outer sole extends from the proximal end of the shoe to a position
beneath the Calcaneum bone about 86-87% of the length of the shoe
rearward from the toe of the shoe.
4. A shoe according to claim 1 in which said first portion of said
outer sole extends from the proximal end of the shoe to a position
beneath the Calcaneum bone about 85% of the length of the shoe
rearward from the toe of the shoe.
5. A shoe according to claim 1 in which said first portion of said
outer sole extends from the proximal end of the shoe to a position
beneath the Talus bone that is about 62.5% of the length of the
shoe rearward from the toe of the shoe.
6. A shoe according to claim 1 in which said first portion of said
outer sole extends from the proximal end of the shoe to a position
beneath the joint between the Metatarsal and Cuneiform bones of the
medial arch about 50% of the length of the shoe rearward from the
toe of the shoe.
7. A shoe according to claim 1 in which said first portion of said
outer sole extends from the proximal end of the shoe to a position
beneath the joint between the Phalange and Metatarsal bones of the
big toe about 25% of the length of the shoe rearward from the toe
of the shoe.
8. A shoe according to claim 1 in which said first portion of said
outer sole is limited to the toe of said shoe.
Description
BACKGROUND OF THE INVENTION
[0001] Field of the Invention
[0002] This invention generally relates to footwear and more
particularly to shoes for use in athletics and rehabilitation that
are tailored for a specific activity and a level of the wearer's
expertise for that activity.
[0003] Description of Related Art
[0004] Shoes suited for physical activities, such as running,
jogging, brisk walking, aerobic exercise and the like which involve
stepping and landing on an individual's feet are well known.
Generally these activities are characterized by suspension and
landing of the foot. In such physical activities the individual's
foot acts as a shock absorber upon landing, a support member during
the period between landing and stepping off, and a spring for
propelling, launching, or stepping from the surface such as the
ground. Despite many advances in the design and construction of
athletic shoes, injuries incurred during such activities continue
to be widespread. Such injuries include heal spurs, plantar fascia,
shin splints, and stress fractures of the sesamoid bones and head
of the metatarsal bones, as well as metatarsalgia. Other
musculoskeletal injuries that can result from these physical
activities include posterior compartment syndromes, calf reaction
syndromes, and various knee, hip, back and scapula problems.
Frequently it is the way an individual lands and then steps off
that leads to these injuries. In many cases inadequacies of the
shoes worn by the individual are a significant contributing
factor.
[0005] The vast majority of walkers, runners and joggers land heel
first on the ground and then push off with the forefoot. However,
during the heel landing the Tibialis Anterior, Extensor Digitorum
Longus, Extensor Halluces, and Peroneus Tertius place the foot in
dorsiflexion. This foot position minimizes the natural shock
absorbing capacity of the foot and often leads to the previously
discussed injuries.
[0006] Forefoot landings, as opposed to heel landings, have proven
to be the most efficient landing pattern during physical activities
that involve such stepping off and landing. During forefoot
landings, the landing forces are applied generally to the dynamic
front part of the foot, or forefoot, comprising the toes and the
ball of the foot simultaneously. The intrinsic muscles of the foot
and the skeletal structure including the gastrocnemius, Soleus,
Plantaris, Tibialis Posterior, Flexor Halluces, Peroneus Longus and
Brevis place the arch of the foot in a proper attitude to act as a
shock absorbing spring as the forefoot impacts a support surface.
Moreover, stepping off from the forefoot without initial heel
contact tends to increase efficiency as there is no effort expended
to roll the foot from the heel to the toe. Forefoot landings also
reduce the strain on the musculoskeletal structure. However,
individuals also must consciously attempt to land on the forefoot.
Frequently they revert to a heel landing when they become fatigued
or otherwise distracted or preoccupied.
[0007] To overcome the injuries associated with heel landings,
makers of various types of athletic shoes generally pad the heel to
provide some shock absorption. While such padding does reduce shock
somewhat, the impact to the heel can still be in the range of three
or more times the individual's weight during jogging. Consequently,
even highly padded heels do not provide a sufficient absorption to
reduce the number of injuries to individuals. That is, reasonable
levels of padding cannot substitute for the shock absorbing system
in an individual's forefoot.
[0008] U.S. Pat. No. 5,694,706 (1997) to Penka for a heelless
athletic shoe which enhances forefoot landing during various
physical activities, inhibits heel landings, enhances an
individual's performance and does not cause the foot to undergo
unnecessary and potentially dangerous dorsiflexion from the step
off to the pre-landing phase. Penka also provides a shoe that is
adapted for use during rehabilitation from injuries caused by
heel-to-toe landing patterns and encourages pre-disposition of the
foot for landing on and immediate stepping off from the forefoot
while not placing undue tension on the Gastrocnemius-Soleus muscle
and the Achilles tendon.
[0009] Such a shoe has an upper and a multiple part lower sole
forming an interior volume for receiving an individual's foot. The
multiple part sole comprises an inner sole, a midsole and an outer
sole. The inner sole engages the plantar surface of the foot. The
midsole is relatively rigid and attaches to the exterior of the
inner sole to be coextensive with at least a portion of the
forefoot and supports the plantar surface of the foot. The front or
proximal section of the outer sole may have a different thickness
according to different embodiments of this invention which
underlies at least a portion of the forefoot and a contiguous rear
portion for underlying the heel. The front section provides a
landing surface for the shoe. The rear portion is thinner than the
landing surface whereby an exterior surface of the rear portion is
elevated relative to the landing surface thereby to prevent heel
landings.
[0010] However, the prior art does not specify the depth or
thickness and the length of the recess area appropriate for
different individuals who engage in different types of activities
at different levels of skill. This lack of specification is leading
to a new trend of musculoskeletal injuries such as calf reaction,
plantar fascia, metatarsalagia and the cuboid syndromes. To help
prevent these injuries, the recess area of the heel must be clearly
defined in depth, length and thickness of the sole of the shoe.
[0011] Therefore, it is the object of this invention to disclose a
heelless shoe grid based on the type of activity or sport the
wearer intends to undertake, the state of individual's physical
conditioning, and the skill level of the wearer in the chosen
activity.
[0012] Another object of the invention is to enhance the
performance of the wearer of such a shoe in their activity of
choice.
[0013] Still another object of the invention is to provide
previously unavailable embodiments for an athletic shoe or shoes
suited for rehabilitation of individuals with various types of
injuries or conditions.
[0014] In accordance with this invention an embodiment of a
heelless shoe has an upper including a toe portion, a midsection
and a rear portion and a multiple part sole forming an interior
volume for receiving an individual's foot. The multiple part sole
comprises an inner sole for engaging the plantar surface of the
foot, a midsole having an inner surface attached to the exterior of
the inner sole to be substantially coextensive with the inner sole,
the midsole having an outer surface, and an outer sole attached to
the outer surface of the midsole intermediate the inner and outer
soles. The outer sole has a first portion extending from the
proximal end of the shoe to a position under the foot selected
according to an intended use of the shoe and a second contiguous
portion extending from the selected position to the distal or rear
portion of the shoe. The first portion of the outer sole provides a
landing surface for the shoe and the second, relatively thin
portion as compared to the first portion thereby inhibiting
landings on the heel for different embodiments of the shoe and
generally promoting an appropriate posture or gait for the wearer
while performing the motions involved in the selected activity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The various objects, advantages and novel features of this
invention will be more fully apparent from a reading of the
following detailed description in conjunction with the accompanying
drawings in which like reference numerals refer to like parts, and
in which:
[0016] FIG. 1 is a side external view of a shoe in accordance with
this invention;
[0017] FIG. 2 is a side cross sectional view of the embodiment of
the shoe shown in FIG. 1;
[0018] FIG. 3 is a table that is useful in understanding this
invention;
[0019] FIGS. 4A through 4F are views illustrating various
embodiments of the present invention as related to the anatomical
structure of a foot for different applications;
[0020] FIG. 5 is a side cross sectional view of an embodiment of
the invention; and
[0021] FIG. 6 is a side cross sectional view of another embodiment
of the invention.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0022] As shown in FIG. 1, a shoe 10 according to this invention
includes an upper 11 that attaches to a multiple part sole 12 to
define a volume for receiving an individual's foot with a toe box
13, a heel box 14, and an intermediate section 15. The multiple
part sole 12 comprises an inner sole 16, a midsole 17 and an outer
sole 20. A first portion 21 of the outer sole 20 defines a landing
surface 22 for engaging a support surface 23 formed by the ground,
floor or the like. Rearward end 24 of the midsole 17 and rearward
end 25 of the outer sole 20 and the first portion 21, respectively,
underlie a portion of the intermediate section 15 proximate the
heel box 14. A relatively thin rear or second portion 28 of the
outer sole 20 extends from the rearward end 25 to underlie the heel
box 14 and define an exposed recessed surface 30 under the heel
that is elevated from the support surface when the shoe 10 is in a
normal resting position as shown in FIG. 1. This construction in
combination with the mechanics of the ankle and foot minimize heel
contact before the landing surface 22 contacts the support surface
23.
[0023] The upper 11 as depicted in FIG. 1 may have any conventional
construction depending upon seasonal factors, foot conditions and
other criteria. In the specific embodiment of FIG. 1, the upper 11
comprises a substantially standard upper with laces 31 for securing
the shoe 10 on an individual's foot 32 (FIG. 2). The upper 11
defines an access aperture 34 through which the individual's ankle
35 extends. Materials for forming the upper 11 can include, for
example, canvas, leather or plastic materials. It will also be
appreciated that although the shoe 10 is depicted as a low-top tie
shoe, the upper can also be made in a mid-top or high-top
arrangement. Velcro.RTM. strips or other tying arrangements can be
substituted for the laces. The shoe could even be constructed as a
loafer with no tying arrangement.
[0024] With reference to FIG. 2, the inner sole 16 extends from a
front or toe end 36 of the toe box 13 through the heel box 14 and
has an upper or inner surface 37 and a lower or outer surface 38.
The upper surface 37 engages a plantar surface 39 of the foot 32.
The lower surface 38 abuts an upper surface 40 of the midsole 17.
Upper heel surface portion of the outer sole 20 extends back beyond
the midsole 17. The inner sole 16 preferably comprises a thin layer
of relatively soft material that resiliently deforms to correspond
to both the shapes of the overlying plantar surface 39 and the
underlying surface 40 and surface portions 41 and 42. A soft, thin
foam having an open cell construction is an example. With reference
to FIG. 2, the midsole 17 preferably comprises a material that is
relatively hard with some elasticity such as various natural and
synthetic cellular foam with small apertures or like. A closed
cell, elastic, pressure deformable foam is an example. The midsole
17 underlies a portion of the toe box 13 and the intermediate
section 15, preferably from a front end 43 proximate the distal
phalanges 45 to the rearward end 24 underlying an area
corresponding to the Calcaneum bone 50.
[0025] Still referring to FIG. 2, the outer sole 20 underlies the
entirety of the shoe 10 and may even wrap around leading and
trailing ends 51 and 52 of the upper 11. The second portion 28 is
preferably thin compared to the combined thicknesses of the
rearward ends 24 and 25 to avoid friction tear. The recessed
surface 30 thus remains substantially spaced from the support
surface 23 upon initial contact by the landing surface 22 during
walking, running, jogging or other similar activities. Further, the
second portion 28 is preferably formed of a substantially rigid,
hard material, such as a non-elastic rubber or any of various
plastic compounds that tend not to deflect under pressure loads
associated with use of the shoe 10. Consequently, the second
portion 28 firmly supports an individual's heel 47 through the
inner sole 16 while maintaining the spacing from the support
surface 23. In comparison, the first portion 21 including the
landing surface 22 is preferably formed of a softer, more flexible
or elastic material, such as other known rubber or plastic
compounds to provide more cushioning while also providing support
and durability during use.
[0026] The spacing, or recess depth D in FIG. 1, of the second
portion 28 above the support surface 23 is based upon a number of
considerations. These include the normal range of foot movement,
typically 20.degree. in dorsiflexion, shoe size, body weight, and
type of activity in which the individual intends to engage, skill
level and any limitations particular to the individual by whom the
shoe is to be worn.
[0027] In accordance with this invention a range of values for a
length, L, of the outer isole 20 and a recess depth D suited to a
typical individual for use during participation in certain common
activities define different values.. In the various embodiments of
this invention, the length L represents the distance from the front
end 36 of the toe box 13 rearward to the beginning 55 of the
recessed portion 28 of the outer sole 20. L.sub.T represents the
full length of the shoe 10 from the tip of the toe 36 to the back
of the heel 57.
[0028] As depicted in FIGS. 3 and 4, the length L suited for a
given individual may vary from the distance "a" between the front
end 36 of the toe box 13 to the apex of the Calcaneus 47, to
shorter lengths b, c, d, e or f corresponding to termination 55 of
the landing surface 22 optimized according to the intended use of
the wearer in a particular type of activity. The approximate
percentage of the length L of the first part of the outer sole 20
relative to the full length of the shoe L.sub.T is given in FIG. 3.
The midsole 17 of the shoe between the inner sole 16 and outer sole
20 is not illustrated in FIG. 4 for simplification. The skeletal
structure of the foot is shown as it would be positioned inside the
shoe as viewed from the inside of the foot so as to particularly
show the medial arch 59 which comprises the metatarsal bone 61, the
cuneiform 63, the navicular 65, the talus 67, the calcaneus 50 and
associated connective tissue (FIG. 2).
[0029] As will be apparent to one skilled in the art, the area of
the forefoot that bears the weight of the body during landing is
closer to the front of the forefoot in an activity such as dance
(L=f) than, for example, basketball (L=b or c). In an activity such
as walking (L=a or b), the landing surface 22 is still longer since
the weight of the body is typically pressing further back towards
the heel of the foot during landing and the greater length of the
landing surface 22 provides for cushioning of the foot from landing
through transfer of the body weight forward during motion through
stepping off while preventing potentially harmful heel strikes.
[0030] Still referring to FIG. 3, in the different options for
length, referring to the different lengths of the first part 22 of
the outer sole 20, the length L of the landing surface is decreased
for an individual engaging in an activity in which the person's
weight lands further forward on the forefoot. For a skilled
athlete, the length of the landing surface as given in FIG. 3 is
generally reduced and the depth of recess D for the shoe
constructed to correspond to the higher end of the ranges
specified. This additional thickness provides for some cushioning.
Also, the thickness of the landing surface and the corresponding
depth of recess D are greater for a skilled athlete than for a
beginner. For example, a walker who is reasonably fit could be
given an embodiment of the shoe where length L=b, whereas a
physically less fit walker would be given an embodiment of the shoe
where length L=a. In general, the depth of recess D would tend to
the greater thickness in the given range for the more physically
fit individual. For simplification, no attempt has been made in
FIGS. 4A to 4F to illustrate the allowable differences in the depth
of recess D between the different embodiments shown.
[0031] The different lengths L of the landing surface 22 correspond
to anatomical features of the individual's foot inside the shoe as
illustrated in FIG. 4A. For the embodiment where L=a, the first
part of the outer sole extends from the tip of the toes 36 rearward
to the region underneath the apex 47 of the calcaneus 50. As known
in the art, with advancing age a person tends to shift the force of
their body weight towards the heel of the foot potentially
contributing to or aggravating injuries as previously discussed.
The recessed heel portion helps to prevent heel strikes and
promotes better posture.
[0032] For a shoe constructed with L=b, the wearer's body weight
while walking at a more stressful pace or during recreational
jogging tends to be or should be shifted more forward on the foot
such that the landing surface ends in front of the apex 47 of the
Calcaneus 50 with a greater depth of recess D. As a result of the
increased stress of these activities, more leg muscle contraction
and energy expenditure is required and the shoe helps the wearer to
maintain a proper posture or gait.
[0033] Similarly, where L=c, corresponding in FIG. 3 to the
activity of a more competitive jogger, a football player, or a
tennis player or the like, proper movements of the wearer do not
involve heel contact of the shoe as the wearer's body weight is
mostly supported by the forefoot in quicker, more forceful
movements. Unlike recreational jogging, quick changes in direction
are often required and a flat-footed stance should generally be
avoided. A greater depth of recess D (by virtue of a thicker
landing surface) is suggested here to cushion the forefoot
particularly given the quicker, more forceful movements
required.
[0034] Following a pattern of increasing stress involved in an
activity, for L=d, where the landing surface terminates below the
Talus as shown in FIG. 5, a more competitive tennis player or a
middle distance runner could benefit from wearing a shoe with a
still further reduced landing surface 22 and a somewhat reduced
depth of recess D by virtue of a reduced amount of cushioning to
provide a more rapid landing and step off, i.e., a quicker reaction
time. Although a reduced amount of cushioning makes for more stress
to the forefoot from the landing, this is an acceptable compromise
for a fit athlete to achieve better performance because the energy
absorbed by the cushioning slows reaction time and, as previously
noted, the medial arch 59 defined by the skeletal structure from
the Metatarsal bone to the Calcaneus functions as a natural spring
which makes forefoot landings preferable to heel strikes in
absorbing shock and preventing injuries at least in a relatively
fit individual.
[0035] As known in the art, sprinting shoes, particularly for
competitive athletes, have little if any cushioning and have a
contact surface 22 only at the front of the shoe which may include
holes into which spikes can be inserted. This is shown in FIG. 4
for the embodiment L=e. Such shoes are intended for competitive
athletes with a reasonable degree of fitness and, as explained
above, can enhance the performance of the wearer by capitalizing on
the natural "springiness" of the forefoot landing and the quick
landing and stepping off. A sprinter's heel should never touch the
ground and a bulky heel cushion is a disadvantage.
[0036] In other embodiments, e.g., L=f or g, a skilled dancer or
gymnast will perform or train with their body weight on the ball of
their foot or even the tips of their toes. FIG. 6 illustrates an
embodiment of the shoe where L=f. These are activities which are
not necessarily suited for an untrained athlete, and many
precautions are taken to prevent many types of injuries to these
athletes in addition to the choice of appropriate footwear. This
invention gives such athletes an option for shoes which may be
suitable for training or during recovery from some kinds of
injuries.
[0037] FIGS. 5 and 6 additionally illustrate example embodiments in
which L=d and L=f, respectively, and the corresponding depth of
recess D in FIG. 3, is generally reduced as compared to FIG. 2 in
which L=a. The features of additional embodiments are discussed
above.
[0038] A shoe according to this invention may be further customized
for an individual based on various factors and the full range of
values for the length L are contemplated between those illustrated
in FIG. 4. It should now be apparent that the actual length L (see
FIG. 3) selected for a particular individual's foot will be
determined by the actual size of the individual's foot and be
informed by a professional fitting the shoe and by the preferences
of the wearer. It is therefore intended that the range of values
given for the depth of recess D in FIG. 3 be exemplary and not
limiting.
EXAMPLE 1
[0039] As an example of how an athletic shoe according to the
present invention might be properly tailored to a particular
individual, assume the intended wearer is a middle-aged woman who
wants to lose extra weight by engaging in walking. This individual
has had a previous injury to her right knee which may be aggravated
by heel strikes while walking. According to FIG. 3, an appropriate
length L=a is recommended for the individual by the professional
fitting her for a shoe who would also determine her proper shoe
size. Because the individual is overweight and has a history of
injury, the professional selects a recess depth D of 10 mm for the
right shoe to be worn by this individual to both provide
appropriate cushioning and comfort while preventing heel strikes
which may aggravate her previous injury. As known in the art,
additional support features not limited to this invention may be
included in the structure of the shoe. The professional fitting
this woman might select a similar left shoe according to this
invention for the same woman.
EXAMPLE 2
[0040] As a second example, assume the intended wearer of the shoe
is a relatively fit college runner who competes in middle-distance
races. The professional fitting the shoe selects a length L=c for
the landing surface 22 (FIG. 3), and a 3 mm depth of recess D for
this runner. As discussed previously, a more competitive
middle-distance runner will land on the running surface with her
body weight more forward on the forefoot and is sufficiently fit
such that having less cushioning on the landing surface of the shoe
resulting in greater impact force on the foot is an acceptable
compromise to achieve better performance provided by a quicker
landing and step off.
EXAMPLE 3
[0041] Altering the scenario above such that the middle-distance
runner, though fit, has had a prior injury to her right knee, a 10
mm depth of recess D might be appropriate to provide some
cushioning with protection from heel strikes or discomfort while
still providing acceptable performance characteristics for the
competitive runner. The possible variations of this invention are
numerous, but the utility of the invention in many possible
scenarios should now be apparent to one skilled in the art.
[0042] In summary, an athletic shoe 10 constructed in accordance
with this invention includes a proximal sole portion of a multiple
part sole with a landing surface composed of a pressure deformable
material under at least part of the forefoot, with the exception of
L=g (need clarification here). The extent and thickness of the
landing surface constructed for a particular embodiment of the shoe
is determined with reference to a grid matching possible intended
uses for the shoe to a suggested range of values for the length L
of the landing surface 22 from the toe of the shoe rearward and the
depth of the recess between the back portion of the heelless shoe
and the ground. The embodiments of the invention disclosed provide
a guide to the selection of a shoe suited to the particular needs
of an individual, which may enhance the performance of the wearer
in a particular activity, help to prevent injuries known to occur
with other types of footwear existing in the prior art and provide
additional options for rehabilitation for individuals having
certain types of injuries or limitations.
[0043] This invention has been disclosed in terms of certain
embodiments. It will be apparent that many modifications can be
made to the disclosed apparatus without departing from the
invention. Therefore, it is the intent of the appended claims to
cover all such variations and modifications as come within the true
spirit and scope of this invention.
* * * * *