U.S. patent application number 15/818300 was filed with the patent office on 2019-05-23 for adjustable steering column assembly.
The applicant listed for this patent is THYSSENKRUPP AG, THYSSENKRUPP PRESTA AG. Invention is credited to Sascha Fricke.
Application Number | 20190152508 15/818300 |
Document ID | / |
Family ID | 66534297 |
Filed Date | 2019-05-23 |
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United States Patent
Application |
20190152508 |
Kind Code |
A1 |
Fricke; Sascha |
May 23, 2019 |
ADJUSTABLE STEERING COLUMN ASSEMBLY
Abstract
One steering column assembly includes an outer jacket having a
first end, a cavity defined by an inner surface extending from the
first end, and protrusions extending from the inner surface into
the cavity. Each protrusion includes a front end at or adjacent the
first end, a rear end, and a curved contact surface telescopically
supporting an inner jacket. The front end has first and second
endpoints, the rear end has third and fourth endpoints, and one
side connects the first and third endpoints while another side
connects the second and fourth endpoints. Each protrusion is
configured such that, when the front and rear ends and the sides
are projected onto a flat surface and an angle is measured between
one straight line passing through the first and third endpoints and
another straight line passing through the second and fourth
endpoints, the measurement is from one to fifteen degrees.
Inventors: |
Fricke; Sascha; (Hard,
AT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THYSSENKRUPP PRESTA AG
THYSSENKRUPP AG |
Eschen
Essen |
|
LI
DE |
|
|
Family ID: |
66534297 |
Appl. No.: |
15/818300 |
Filed: |
November 20, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B62D 1/185 20130101;
B62D 1/181 20130101 |
International
Class: |
B62D 1/185 20060101
B62D001/185; B62D 1/181 20060101 B62D001/181 |
Claims
1. A steering column assembly for use with a vehicle, comprising: a
steering shaft having a longitudinal axis; an inner jacket
supporting the steering shaft with the steering shaft being
rotatable about the longitudinal axis; and an outer jacket
comprising: a first end that is passenger facing and an opposite
second end; a cavity defined by an inner surface extending from the
first end toward the second end; and at least two protrusions
extending from the inner surface into the cavity, each protrusion
comprising: a curved contact surface; a front end at or adjacent
the outer jacket first end, the front end having first and second
endpoints with a front arc length therebetween; a rear end
extending toward the outer jacket second end, the rear end having
third and fourth endpoints with a rear arc length therebetween; and
two sides respectively connecting the first and second endpoints of
the front end with the third and fourth endpoints of the rear end,
such that a first of the sides is associated with the first and
third endpoints and a second of the sides is associated with the
second and fourth endpoints; wherein each of the at least two
protrusions is configured such that: (a) projecting the front end,
the rear end, and the two sides onto a flat surface; and (b)
measuring an angle between one straight line passing through the
first and third endpoints and another straight line passing through
the second and fourth endpoints results in an angular measurement
of at least one degree and no more than fifteen degrees; and
wherein the curved contact surface of each of the at least two
protrusions supports the inner jacket with the inner jacket being
telescopic along the longitudinal axis.
2. The steering column assembly of claim 1, wherein the angular
measurement is at least one degree and no more than three
degrees.
3. The steering column assembly of claim 1, wherein the front arc
length is larger than the rear arc length.
4. The steering column assembly of claim 1, wherein the front arc
length is smaller than the rear arc length.
5. The steering column assembly of claim 1, wherein each of the two
sides is linear.
6. The steering column assembly of claim 1, wherein each of the two
sides is concave.
7. The steering column assembly of claim 1, wherein each of the two
sides is convex.
8. The steering column assembly of claim 1, wherein the at least
two protrusions is three protrusions.
9. The steering column assembly of claim 1, further comprising an
actuator for moving the inner jacket relative to the outer jacket
along the longitudinal axis.
10. The steering column assembly of claim 9, wherein the steering
shaft has an end for receiving a steering wheel.
11. A steering column assembly for use with a vehicle, comprising:
a steering shaft having a longitudinal axis; an inner jacket
supporting the steering shaft with the steering shaft being
rotatable about the longitudinal axis; and an outer jacket
comprising: a first end and an opposite second end; a cavity
defined by an inner surface extending from the first end toward the
second end; and at least two protrusions extending from the inner
surface into the cavity, each protrusion comprising: a curved
contact surface; a front end at or adjacent the outer jacket first
end, the front end having first and second endpoints with a front
arc length therebetween; and a rear end extending toward the outer
jacket second end and being spaced apart from the front end by a
fixed length, the rear end having third and fourth endpoints with a
rear arc length therebetween; wherein each of the at least two
protrusions is configured such that: (a) projecting the front end
and the rear end onto a flat surface with the front end being
separated from the rear end by the fixed length, the first and
second endpoints being perpendicularly equidistant from a
centerline, the third and fourth endpoints being perpendicularly
equidistant from the centerline, the first and third endpoints
being on one side of the centerline, and the second and fourth
endpoints being on an opposite side of the centerline; and (b)
measuring an angle between one straight line passing through the
first and third endpoints and another straight line passing through
the second and fourth endpoints results in an angular measurement
of at least one degree and no more than fifteen degrees; and
wherein the curved contact surface of each of the at least two
protrusions supports the inner jacket with the inner jacket being
telescopic along the longitudinal axis.
12. The steering column assembly of claim 11, wherein the angular
measurement is at least one degree and no more than three
degrees.
13. The steering column assembly of claim 11, wherein the angular
measurement is two degrees.
14. The steering column assembly of claim 11, wherein the front arc
length is larger than the rear arc length.
15. The steering column assembly of claim 11, wherein the front arc
length is smaller than the rear arc length.
16. The steering column assembly of claim 11, wherein the at least
two protrusions is three protrusions.
17. The steering column assembly of claim 11, further comprising an
actuator for moving the inner jacket relative to the outer jacket
along the longitudinal axis.
18. An outer jacket for use in a vehicle steering column assembly
to telescopically support an inner jacket, the outer jacket
comprising: a first end and an opposite second end; a cavity
defined by an inner surface extending from the first end toward the
second end; and at least two protrusions extending from the inner
surface into the cavity, each protrusion comprising: a curved
contact surface; a front end at or adjacent the outer jacket first
end, the front end having first and second endpoints with a front
arc length therebetween; a rear end extending toward the outer
jacket second end, the rear end having third and fourth endpoints
with a rear arc length therebetween; and two sides respectively
connecting the first and second endpoints of the front end with the
third and fourth endpoints of the rear end, such that a first of
the sides is associated with the first and third endpoints and a
second of the sides is associated with the second and fourth
endpoints; wherein each of the at least two protrusions is
configured such that: (a) projecting the front end, the rear end,
and the two sides onto a flat surface; and (b) measuring an angle
between one straight line passing through the first and third
endpoints and another straight line passing through the second and
fourth endpoints results in an angular measurement of at least one
degree and no more than fifteen degrees.
19. The steering column assembly of claim 18, wherein the angular
measurement is at least one degree and no more than three
degrees.
20. The steering column assembly of claim 18, wherein each of the
sides is selected from the group consisting of: straight, concave,
and convex.
Description
FIELD OF THE DISCLOSURE
[0001] The disclosure relates generally to the field of steering
column assemblies for motor vehicles. More specifically, the
disclosure relates to adjustable steering column assemblies.
SUMMARY
[0002] The following presents a simplified summary of the
disclosure in order to provide a basic understanding of some
aspects of the disclosure. This summary is not an extensive
overview of the disclosure. It is not intended to identify critical
elements of the disclosure or to delineate the scope of the
disclosure. Its sole purpose is to present some concepts of the
disclosure in a simplified form as a prelude to the more detailed
description that is presented elsewhere.
[0003] According to an embodiment, a steering column assembly is
provided for use with a vehicle. The steering column assembly
includes a steering shaft having a longitudinal axis, an inner
jacket supporting the steering shaft with the steering shaft being
rotatable about the longitudinal axis, and an outer jacket. The
outer jacket includes a first end that is passenger facing and an
opposite second end, a cavity defined by an inner surface extending
from the first end toward the second end, and at least two
protrusions extending from the inner surface into the cavity. Each
protrusion includes a curved contact surface, a front end at or
adjacent the outer jacket first end, and a rear end extending
toward the outer jacket second end. The front end has first and
second endpoints with a front arc length therebetween, the rear end
has third and fourth endpoints with a rear arc length therebetween,
and two sides respectively connect the first and second endpoints
of the front end with the third and fourth endpoints of the rear
end, such that a first of the sides is associated with the first
and third endpoints and a second of the sides is associated with
the second and fourth endpoints. Each of the at least two
protrusions is configured such that, when the front end, the rear
end, and the two sides are projected onto a flat surface and an
angle is measured between one straight line passing through the
first and third endpoints and another straight line passing through
the second and fourth endpoints, the resulting angular measurement
is at least one degree and no more than fifteen degrees. And the
curved contact surface of each of the at least two protrusions
supports the inner jacket with the inner jacket being telescopic
along the longitudinal axis.
[0004] In an embodiment, the angular measurement is at least one
degree and no more than three degrees.
[0005] In an embodiment, the front arc length is larger than the
rear arc length.
[0006] In an embodiment, the front arc length is smaller than the
rear arc length.
[0007] In an embodiment, each of the two sides is linear.
[0008] In an embodiment, each of the two sides is concave.
[0009] In an embodiment, each of the two sides is convex.
[0010] In an embodiment, the at least two protrusions is three
protrusions.
[0011] In an embodiment, the at least two protrusions is four
protrusions.
[0012] In an embodiment, the at least two protrusions is five
protrusions.
[0013] In an embodiment, the steering column assembly further
includes an actuator for moving the inner jacket relative to the
outer jacket along the longitudinal axis.
[0014] In an embodiment, the steering shaft has an end for
receiving a steering wheel.
[0015] According to another embodiment, a steering column assembly
for use with a vehicle includes a steering shaft having a
longitudinal axis, an inner jacket supporting the steering shaft
with the steering shaft being rotatable about the longitudinal
axis, and an outer jacket. The outer jacket includes a first end
and an opposite second end, a cavity defined by an inner surface
extending from the first end toward the second end, and at least
two protrusions extending from the inner surface into the cavity.
Each protrusion includes a curved contact surface, a front end at
or adjacent the outer jacket first end, and a rear end extending
toward the outer jacket second end and being spaced apart from the
front end by a fixed length. The front end has first and second
endpoints with a front arc length therebetween, and the rear end
has third and fourth endpoints with a rear arc length therebetween.
Each of the at least two protrusions is configured such that, when
the front end and the rear end are projected onto a flat surface
with the front end being separated from the rear end by the fixed
length, the first and second endpoints being perpendicularly
equidistant from a centerline, the third and fourth endpoints being
perpendicularly equidistant from the centerline, the first and
third endpoints being on one side of the centerline, and the second
and fourth endpoints being on an opposite side of the centerline,
the resulting angular measurement between one straight line passing
through the first and third endpoints and another straight line
passing through the second and fourth endpoints is at least one
degree and no more than fifteen degrees. And the curved contact
surface of each of the at least two protrusions supports the inner
jacket with the inner jacket being telescopic along the
longitudinal axis.
[0016] In an embodiment, the angular measurement is at least one
degree and no more than three degrees.
[0017] In an embodiment, the angular measurement is two
degrees.
[0018] In an embodiment, the front arc length is larger than the
rear arc length.
[0019] In an embodiment, the front arc length is smaller than the
rear arc length.
[0020] In an embodiment, the at least two protrusions is three
protrusions.
[0021] In an embodiment, the at least two protrusions is four
protrusions.
[0022] In an embodiment, the at least two protrusions is five
protrusions.
[0023] In an embodiment, the steering column assembly further
includes an actuator for moving the inner jacket relative to the
outer jacket along the longitudinal axis.
[0024] According to still another embodiment, an outer jacket is
provided for use in a vehicle steering column assembly to
telescopically support an inner jacket. The outer jacket includes a
first end and an opposite second end, a cavity defined by an inner
surface extending from the first end toward the second end, and at
least two protrusions extending from the inner surface into the
cavity. Each protrusion includes a curved contact surface, a front
end at or adjacent the outer jacket first end, and a rear end
extending toward the outer jacket second end. The front end has
first and second endpoints with a front arc length therebetween,
and the rear end has third and fourth endpoints with a rear arc
length therebetween. Two sides respectively connect the first and
second endpoints of the front end with the third and fourth
endpoints of the rear end, such that a first of the sides is
associated with the first and third endpoints and a second of the
sides is associated with the second and fourth endpoints. Each of
the at least two protrusions is configured such that, when the
front end, the rear end, and the two sides are projected onto a
flat surface and an angle is measured between one straight line
passing through the first and third endpoints and another straight
line passing through the second and fourth endpoints, the resulting
angular measurement is at least one degree and no more than fifteen
degrees.
[0025] In an embodiment, the angular measurement is at least one
degree and no more than three degrees.
[0026] In an embodiment, each of the sides is selected from the
group consisting of straight, concave, and convex.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0027] FIG. 1 is a perspective view showing an adjustable steering
column assembly, according to an embodiment of the present
disclosure.
[0028] FIG. 2 is a perspective view showing the outer jacket of the
steering column assembly of FIG. 1.
[0029] FIG. 3 is another perspective view showing the outer jacket
of FIG. 2.
[0030] FIG. 4 schematically illustrates an interior area of the
outer jacket of FIG. 2, projected as a flat surface.
[0031] FIG. 5 is a perspective view showing an alternate outer
jacket for use with the steering column assembly of FIG. 1.
[0032] FIG. 6 is another perspective view showing the outer jacket
of FIG. 5.
[0033] FIG. 7 schematically illustrates an interior area of the
outer jacket of FIG. 5, projected as a flat surface.
[0034] FIG. 8 schematically illustrates an alternate interior area
for use in the outer jacket of FIG. 5, projected as a flat
surface.
[0035] FIG. 9 schematically illustrates another alternate interior
area for use in the outer jacket of FIG. 5, projected as a flat
surface.
DETAILED DESCRIPTION
[0036] Steering column assemblies that allow a steering wheel to
move toward and away from a driver along a longitudinal axis of a
steering shaft are known in the art, and actuators such as electric
motors are used to move the steering shaft longitudinally. For
example, U.S. 2015/0251683 to Caverly, assigned to STEERING
SOLUTIONS IP HOLDING CORPORATION, the contents of which are hereby
incorporated in their entirety by reference, discloses a steering
wheel capable of moving longitudinally. The '683 Publication
provides telescopic outer (or "lower") and inner (or "upper")
jackets, and the outer jacket has a flat cylindrical inner surface
to support the inner jacket. While that configuration may
ultimately allow the inner jacket to move to desired positions,
embodiments of the present disclosure may have improved performance
over the prior art in increasing eigenfrequency and stiffness of
the steering column.
[0037] FIG. 1 illustrates an adjustable steering column assembly
100, according to one embodiment. The adjustable steering column
assembly 100 broadly includes an outer (or "lower") jacket 110, an
inner (or "upper") jacket 130, and a steering shaft (or "spindle")
150. The outer jacket 110 telescopically supports the inner jacket
130, and the inner jacket 130 rotatably supports the steering shaft
150 about a longitudinal axis 150a of the steering shaft 150 (such
as through bearings). A steering wheel is coupled (directly or
indirectly) to end 151 of the steering shaft 150, and rotation of
the steering wheel causes the steering shaft 150 to rotate--which
ultimately causes an automobile having the steering column assembly
100 to turn. The outer jacket 110 may be fastened to a bracket 102
which is coupled to the vehicle's chassis or other environmental
structure, and may be allowed to tilt and lock relative to the
bracket 102; accordingly, a driver may be able to incline the
steering wheel in accordance with his preferences, though only
along a predetermined range of motion. And an actuator 170 (for
example, an electric motor, a hydraulic motor, et cetera) may cause
the inner jacket 130 to move relative to the outer jacket 110 along
the longitudinal axis 150a.
[0038] In the embodiment of FIG. 1, the actuator 170 includes an
electric motor 171 and gearing for using rotational motion of the
electric motor 171 to move the inner jacket 130 telescopically.
More specifically, a drive bracket 172 cooperates with a leadscrew
173 to transfer linear motion to the inner jacket 130 during
telescopic adjustment of the steering column assembly 100. When
telescopic movement is commanded, the actuator 170 is operated to
vary the telescopic relationship between the inner jacket 130 and
the outer jacket 110.
[0039] Focusing now on the outer jacket 110, the outer jacket 110
has a first end 112a that is passenger facing (i.e., which faces a
passenger compartment of the vehicle) and an opposite second end
112b, and a cavity 114 defined by an inner surface 113 extends from
the first end 112a toward the second end 112b. The outer jacket 110
may include at least one slit 115 extending from the cavity 114 for
guiding the inner jacket 130, and at least two protrusions 121
extend from the inner surface 113 into the cavity 114. In some
embodiments, it may be desirable to have three, four, or five
protrusions 121, and particularly desirable to have three
protrusions 121.
[0040] Each protrusion 121 has a curved contact surface 122 for
contacting (and supporting) the inner jacket 130, a front end 123,
a rear end 124 spaced apart from the front end 123 by a fixed
length, and sides 125a, 125b connecting the front and rear ends
123, 124. And each protrusion front end 123 is at or adjacent the
jacket first end 112a, while each protrusion rear end 124 extends
toward the jacket second end 112b. Each protrusion front end 123
has endpoints 123a, 123b with an arc length 123c therebetween, and
each protrusion rear end 124 has endpoints 124a, 124b with an arc
length 124c therebetween, and the arc lengths 123c, 124c are
illustrated in FIG. 4 as being projected onto a flat surface along
with the sides 125a, 125b. The side 125a of each protrusion 121
connects the end points 123a, 124a, and the side 125b of each
protrusion 121 connects the end points 123b, 124b. In the
embodiment 100, the front arc length 123c is smaller than the rear
arc length 124c. In the projection onto a flat surface (FIG. 4),
the front and rear ends 123, 124 are separated by the fixed length,
the endpoints 123a, 123b are perpendicularly equidistant from a
centerline 129, and the endpoints 124a, 124b are perpendicularly
equidistant from the centerline 129. Moreover, the endpoints 123a,
124a are on one side of the centerline 129, and the endpoints 123b,
124b are on an opposite side of the centerline 129.
[0041] An angle A1 is defined on each projected protrusion profile
(FIG. 4) between one straight line 126a passing through the end
points 123a, 124a and another straight line 126b passing through
the end points 123b, 124b. If the sides 125a, 125b are linear (such
as shown in FIGS. 3 and 4), the lines 126a, 126b align with the
sides 125a, 125b. In some embodiments, it is critical for improved
eigenfrequency characteristics and/or improved stiffness of the
adjustable steering column assembly 100 that the angle A1 is at
least one degree and no more than fifteen degrees, it may be
particularly desirable that the angle A1 be at least one degree and
no more than three degrees, and it may be even more particularly
desirable that the angle A1 be two degrees.
[0042] In use, a driver may adjust the tilt of the steering shaft
150 using the bracket 102 as discussed above, and may use the
actuator to move the steering shaft 150 toward or away from the
vehicle's passenger cabin (i.e., along the longitudinal axis 150a).
The configuration of the protrusions 121, and particularly the
value of angle A1, is critical in increasing the eigenfrequency and
stiffness of the steering column assembly 100, as the protrusions
121 support the inner jacket 130 and may allow the inner jacket 130
to travel smoothly along the longitudinal axis 150a.
[0043] FIGS. 5 through 7 illustrate another outer jacket 210,
according to an embodiment, for use in the adjustable steering
column assembly 100 by replacing the outer jacket 110. The outer
jacket 210 is substantially similar to the outer jacket 110, except
as specifically noted and/or shown, or as would be inherent.
Further, those skilled in the art will appreciate that the
embodiment 110 (and thus the embodiment 210) may be modified in
various ways, such as through incorporating all or part of any of
the various described embodiments, for example. For uniformity and
brevity, reference numbers from 210 to 229 may be used to indicate
elements corresponding to those discussed above numbered from 110
to 129 (e.g., outer jacket 210 corresponds generally to the outer
jacket 110, first end 212a corresponds generally to the first end
112a, second end 212b corresponds generally to the second end 112b,
inner surface 213 corresponds generally to the inner surface 113,
cavity 214 corresponds generally to the cavity 114, slit 215
corresponds generally to the slit 115, protrusion 221 corresponds
generally to the protrusion 121, curved contact surface 222
corresponds generally to the curved contact surface 122, protrusion
front end 223 corresponds generally to the protrusion front end
123, endpoint 223a corresponds generally to the endpoint 123a,
endpoint 223b corresponds generally to the endpoint 123b, arc
length 223c corresponds generally to the arc length 123c,
protrusion rear end 224 corresponds generally to the protrusion
rear end 124, endpoint 224a corresponds generally to the endpoint
124a, endpoint 224b corresponds generally to the endpoint 124b, arc
length 224c corresponds generally to the arc length 124c, side 225a
corresponds generally to the side 125a, side 225b corresponds
generally to the side 125b, line 226a corresponds generally to the
line 126a, line 226b corresponds generally to the line 126b,
centerline 229 corresponds generally to the centerline 129, et
cetera), though with any noted, shown, or inherent deviations.
[0044] The primary difference between the outer jacket 210 and the
outer jacket 110 is that the front arc length 223c is larger than
the rear arc length 224c, while the front arc length 123c is
smaller than the rear arc length 124c. As with the jacket 110, the
value of angle A1 in the outer jacket 210 is preferably at least
one degree and no more than fifteen degrees, more preferably at
least one degree and no more than three degrees, and even more
preferably two degrees.
[0045] FIG. 8 illustrates another protrusion 321 for use in the
adjustable steering column assembly 100 or the adjustable steering
column assembly 200. The protrusion 321 is substantially similar to
the protrusion 221, except as specifically noted and/or shown, or
as would be inherent. Further, those skilled in the art will
appreciate that the protrusion 221 (and thus the protrusion 321)
may be modified in various ways, such as through incorporating all
or part of any of the various described embodiments, for example.
For uniformity and brevity, reference numbers from 321 to 329 may
be used to indicate elements corresponding to those discussed above
numbered from 221 to 229 (e.g., protrusion front end 323
corresponds generally to the protrusion front end 223, endpoint
323a corresponds generally to the endpoint 223a, endpoint 323b
corresponds generally to the endpoint 223b, arc length 323c
corresponds generally to the arc length 223c, protrusion rear end
324 corresponds generally to the protrusion rear end 224, endpoint
324a corresponds generally to the endpoint 224a, endpoint 324b
corresponds generally to the endpoint 224b, arc length 324c
corresponds generally to the arc length 224c, side 325a corresponds
generally to the side 225a, side 325b corresponds generally to the
side 225b, line 326a corresponds generally to the line 226a, line
326b corresponds generally to the line 226b, centerline 329
corresponds generally to the centerline 229, et cetera), though
with any noted, shown, or inherent deviations.
[0046] The primary difference between the protrusion 321 and the
protrusion 221 is that sides 325a, 325b of the protrusion 321 are
concave, while the sides 225a, 225b are linear. As with the
protrusion 221, the value of angle A1 in the protrusion 321 is
preferably at least one degree and no more than fifteen degrees,
more preferably at least one degree and no more than three degrees,
and even more preferably two degrees.
[0047] FIG. 9 illustrates another protrusion 421 for use in the
adjustable steering column assembly 100 or the adjustable steering
column assembly 200. The protrusion 421 is substantially similar to
the protrusion 121, except as specifically noted and/or shown, or
as would be inherent. Further, those skilled in the art will
appreciate that the protrusion 121 (and thus the protrusion 421)
may be modified in various ways, such as through incorporating all
or part of any of the various described embodiments, for example.
For uniformity and brevity, reference numbers from 421 to 429 may
be used to indicate elements corresponding to those discussed above
numbered from 121 to 129 (e.g., protrusion front end 423
corresponds generally to the protrusion front end 123, endpoint
423a corresponds generally to the endpoint 123a, endpoint 423b
corresponds generally to the endpoint 123b, arc length 423c
corresponds generally to the arc length 123c, protrusion rear end
424 corresponds generally to the protrusion rear end 124, endpoint
424a corresponds generally to the endpoint 124a, endpoint 424b
corresponds generally to the endpoint 124b, arc length 424c
corresponds generally to the arc length 124c, side 425a corresponds
generally to the side 125a, side 425b corresponds generally to the
side 125b, line 426a corresponds generally to the line 126a, line
426b corresponds generally to the line 126b, centerline 429
corresponds generally to the centerline 129, et cetera), though
with any noted, shown, or inherent deviations.
[0048] The primary difference between the protrusion 421 and the
protrusion 121 is that sides 425a, 425b of the protrusion 421 are
concave, while the sides 125a, 125b are linear. As with the
protrusion 121, the value of angle A1 in the protrusion 421 is
preferably at least one degree and no more than fifteen degrees,
more preferably at least one degree and no more than three degrees,
and even more preferably two degrees.
[0049] Many different arrangements of the various components
depicted, as well as components not shown, are possible without
departing from the spirit and scope of the present disclosure.
Embodiments of the present disclosure have been described with the
intent to be illustrative rather than restrictive. Alternative
embodiments will become apparent to those skilled in the art that
do not depart from its scope. A skilled artisan may develop
alternative means of implementing the aforementioned improvements
without departing from the scope of the present disclosure. It will
be understood that certain features and subcombinations are of
utility and may be employed without reference to other features and
subcombinations and are contemplated within the scope of the
claims. The specific configurations and contours set forth in the
accompanying drawings are illustrative and not limiting.
* * * * *