U.S. patent application number 15/946266 was filed with the patent office on 2018-10-11 for gearless spring washer high torque device.
This patent application is currently assigned to ECA Medical Instruments. The applicant listed for this patent is ECA Medical Instruments. Invention is credited to David Ivinson, John Nino, David Tory.
Application Number | 20180290273 15/946266 |
Document ID | / |
Family ID | 58488510 |
Filed Date | 2018-10-11 |
United States Patent
Application |
20180290273 |
Kind Code |
A1 |
Tory; David ; et
al. |
October 11, 2018 |
Gearless Spring Washer High Torque Device
Abstract
Disposable torque-limiting mechanisms with upper shank component
with a torque-limiting interface, a lower shank component with a
torque-limiting interface, and a washer assembly biasing element.
Torque-limiting interfaces having a plurality of undulations
arranged around an axial bore or drive socket and separated by a
plurality of transition regions, with each undulation having an
upslope, a peak, and a downslope. The torque-limiting interfaces
are configured to engage and disengage to provide torque
transmission with predetermined torque limits at various rotational
speeds and for amounts of actuations while remaining within a
specified operational range.
Inventors: |
Tory; David; (Los Angeles,
CA) ; Ivinson; David; (Camarillo, CA) ; Nino;
John; (Simi Valley, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ECA Medical Instruments |
Newbury Park |
CA |
US |
|
|
Assignee: |
ECA Medical Instruments
Newbury Park
CA
|
Family ID: |
58488510 |
Appl. No.: |
15/946266 |
Filed: |
April 5, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/US2016/055798 |
Oct 6, 2016 |
|
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15946266 |
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62345607 |
Jun 3, 2016 |
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62238419 |
Oct 7, 2015 |
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62238359 |
Oct 7, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61B 17/8875 20130101;
B25B 23/147 20130101; B25B 23/0035 20130101; F16D 7/044 20130101;
B25B 23/141 20130101; A61B 2090/031 20160201 |
International
Class: |
B25B 23/14 20060101
B25B023/14; B25B 23/00 20060101 B25B023/00; A61B 17/88 20060101
A61B017/88 |
Claims
1. A disposable torque limiting device comprising: a generally
hollow cylindrical body (14) with a partially closed distal end
(16); an upper shank (200) formed inside the partially closed
distal end of the cylindrical body; a circumferential rim (17)
formed on the outside of the partially closed dial end; an upper
torque-limiting interface (250) formed on the inside of the
partially closed distal end having a axial bore (210); a lower
shank component (100) comprising a proximal end (101), a distal end
(102), a neck (125) extending from the distal end a drive socket
(110) fluidly connecting the proximal end and the distal end, and a
lower torque-limiting interface (150) disposed on the proximal end;
wherein the lower shank component is rotatable with in the
cylindrical body and the upper shank component and the lower shank
component are aligned along an axis (50) in the direction of the
axial bore, the lower shank component is rotatable with in the
cylindrical body and the drive socket with the first
torque-limiting interface in contact with the second
torque-limiting interface; a Multiple Belleville Washer Assembly
"MBWA" (70) is placed above the lower shank on at least partially
around the neck configured to apply compressive force (F) along the
axis to compress the first torque-limiting interface against the
second torque-limiting interface; a tool collar (20) with a flange
(22) extending radially, a front (23) on one side of the flange, a
square leg (25) formed on the opposite of the flange and a shaped
channel (29) there through rotatably fit into the circumferential
rim; a tool shaft (32) with a threaded back portion (35) and a
front end (31) having a tool channel (34) therein; catches (33)
formed on the tool shaft configured to mate with the shaped channel
whereby the tool shaft can be inserted through the tool collar but
rotate within the shaped channel; a threaded (37) retaining member
(38) configure to engage the threaded back portion; wherein the
tool shaft and threaded retaining member cooperate to apply a
predetermined force to the lower and upper shanks via affixation of
the tool shaft through the tool collar, the axial bore, the drive
socket and the MBWA and affixing the retaining member thereto.
2. The device of claim 1 wherein: the MBWA configured to apply
compressive force (F) along the axis to compress the first
torque-limiting interface against the second torque-limiting
interface; the upper shank component and the lower shank component
are configured to engage to rotate together when torque is applied
to the lower shank component via the drive socket; and, the upper
shank component and the lower shank component are configured to
disengage when a predetermined torque limit is exceeded.
3. The device of claim 1 further comprising a plastic high
lubricity washer between the flange and the circumferential
rim.
4. The device of claim 1 further comprising a roller bearing washer
(36') between the flange and the circumferential rim.
5. The device of claim 1 further comprising a tool (40) in the tool
channel.
6. The device of claim 1 wherein the MBWA is configured to have at
least one grouping of three core (75) to base (74) members (73) in
the MBWA.
7. The device of claim 6 wherein the first torque-limiting
interface and second torque-limiting interface each comprise three
undulations (220).
8. The device of claim 7 wherein each undulation is a complex
shaped wave which limits degradation of inexpensive plastic
materials and provides nominal torque.
9. The device of claim 7 further comprising a first section of each
undulation with a higher shoulder (400) near the center (401) of
the shank and a slope downward (402) to the perimeter of the shank
(403); a second section having a wide plateau (404); a third
section having a plateau (406) wider than the second section; a
fourth section having a plateau (408) with height ("H") greater
than all other section; and, a fifth section forming a sloped
transition region (410).
10. The device of claim 1 wherein the MBWA is configured to have at
least three core to base members facing at least three base to core
members positioned between two flat washers (36A/36B).
11. A disposable torque limiting device comprising: a generally
hollow cylindrical body (14) with a partially closed distal end
(16); an upper shank (200) formed inside the partially closed
distal end of the cylindrical body; a circumferential rim (17)
formed on the outside of the partially closed dial end; an upper
torque-limiting interface (250) having undulations formed on the
inside of the partially closed distal end having a axial bore
(210); a lower shank component (100) rotatable placed within the
cylindrical body comprising a proximal end (101), a distal end
(102), a retaining cavity (103) formed thereon, a drive socket
(110) fluidly connecting the proximal end and the distal end, and a
lower torque-limiting interface (150) having undulations disposed
on the proximal end, wherein the upper shank component and the
lower shank component are aligned along an axis (50) in the
direction of the axial bore and the drive socket with the first
torque-limiting interface in contact with the second
torque-limiting interface; an MBWA placed above the lower shank
inside the retaining cavity configured to apply compressive force
(F) along the axis to compress the first torque-limiting interface
against the second torque-limiting interface at a predetermined
torque limit; a tool collar (20) with a flange (22) extending
radially, a front (23) on one side of the flange, a square leg (25)
formed on the opposite of the flange and a shaped channel (29)
there through rotatably fit into the circumferential rim; a tool
shaft (32) with a threaded back portion (35) and a front end (31)
having a tool channel (34) therein; catches (33) formed on the tool
shaft configured to mate with the shaped channel whereby the tool
shaft can be inserted through the tool collar but rotate within the
shaped channel; a threaded (37) retaining member (38) configure to
engage the threaded back portion;
12. The device of claim 11 wherein each undulation is a complex
shaped wave which limits degradation of inexpensive plastic
materials and provides nominal torque.
13. The device of claim 12 further comprising: a first section of
each undulation with a higher shoulder (400) near the center (401)
of the shank and a slope downward (402) to the perimeter of the
shank (403); a second section having a wide plateau (404); a third
section having a plateau (406) wider than the second section; a
fourth section having a plateau (408) with height ("H") greater
than all other section; and, a fifth section forming a sloped
transition region (410); and, wherein the tool shaft and threaded
retaining member cooperate to apply a predetermined force to the
lower and upper shanks via the affixation of the tool shaft through
the tool collar, the axial bore, the drive socket and the RSM and
affixing the retaining member thereto.
14. The device of claim 13 wherein: the MBWA is configured to apply
compressive force (F) along the axis to compress the first
torque-limiting interface against the second torque-limiting
interface; the upper shank component and the lower shank component
are configured to engage to rotate together when torque is applied
to the lower shank component via the drive socket; and, the upper
shank component and the lower shank component are configured to
disengage when a predetermined torque limit is exceeded.
15. The device of claim 11 further comprising a roller bearing
washer (36') between the flange and the circumferential rim.
16. The torque-limiting device of claim 11 wherein: the undulations
of the first torque-limiting interface are arranged around the
axial bore and separated by a first plurality of transition regions
(224); the undulations of the second torque-limiting interface are
arranged around the drive socket and separated by a second
plurality of transition regions (124), the first and second
pluralities being equal in number; and each undulation comprises an
upslope (121/221), a peak (122/222), and a downslope (123/223).
17. The torque-limiting device of claim 16 wherein each upslope has
an inclination angle between about 3 degrees and about 15
degrees.
18. The torque-limiting device of claim 16 wherein each upslope has
an inclination angle between about 5 degrees and about 9
degrees.
19. The torque-limiting device of claim 16 wherein the
predetermined torque limit is between about 0.1 Newton-meters and
3.0 Newton-meters.
20. The torque-limiting device of claim 16 wherein the
predetermined torque limit is between about 3.0 Newton-meters and
6.0 Newton-meters.
21. The torque-limiting device of claim 16 wherein the first
torque-limiting interface and second torque-limiting interface each
comprise between two and five undulations.
23. The torque-limiting device of claim 13 further comprising a
power unit attached to the drive shaft.
24. The torque-limiting device of claim 13 wherein the
torque-limiting mechanism provides a predetermined torque between
about 0.1 Newton-meters and about 6 Newton-meters of torque at a
rotational speed between about 50 RPM and about 1300 RPM over at
least one of 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 105, 110,
120, 150, 180, 200, 220, 250, 300, 350, 400, 450, 500, 550, 600,
650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200,
1250, 1300, 1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750,
1800, 1850, 1900, 1950, 2000, 2100, 2200, 2300, 2400, or 2500
actuations while remaining within a specified operational range.
Description
CROSS-REFERENCE
[0001] This application is continuation of International Patent
Application PCT/US2016/055798 filed Oct. 6, 2016, which claims
priority to U.S. Provisional Patent Application 62/238,419, filed
Oct. 7, 2015, U.S. Provisional Patent Application 62/238,359, filed
Oct. 7, 2015, U.S. Provisional Patent Application 62/345,607, filed
Jun. 3, 2016, the contents of which are incorporated here in their
entirety.
BACKGROUND
1. Field
[0002] This disclosure relates to gearless torque drives for
torque-limiting devices that are suitable for operation at high
rotational speeds.
2. General Background
[0003] Torque is a measure of force acting on an object that causes
that object to rotate. In the case of a driver and a fastener, this
measurement can be calculated mathematically in terms of the cross
product of specific vectors:
.tau.=r.times.F
[0004] Where r is the vector representing the distance and
direction from an axis of a fastener to a point where the force is
applied and F is the force vector acting on the driver.
[0005] Torque has dimensions of force times distance and the SI
unit of torque is the Newton meter (N-m). The joule, which is the
SI unit for energy or work, is also defined as an N-m, but this
unit is not used for torque. Since energy can be thought of as the
result of force times distance, energy is always a scalar whereas
torque is force cross-distance and so is a vector-valued quantity.
Other non-SI units of torque include pound-force-feet,
foot-pounds-force, ounce-force-inches, meter-kilograms-force,
inch-ounces or inch-pounds.
[0006] Torque-limiting drivers are widely used throughout the
medical industry. These torque-limiting drivers have a factory
pre-set torque to ensure the accuracy and toughness required to
meet a demanding surgical environment.
[0007] The medical industry has made use of both reusable and
disposable torque-limiting drivers. In a surgical context, there is
little room for error and these drivers must impart a precise
amount of torque.
[0008] Reusable drivers require constant recalibration to ensure
that the driver is imparting the precise amount of torque.
Recalibration is a cumbersome task but must be done routinely. Such
reusable devices also require sterilization.
[0009] Disposable drivers are an alternative to the reusable
drivers. Once the driver has been used, it is discarded.
[0010] Disposable drivers are traditionally used for low torque
applications. The standard torque values in these applications
typically range from about 4 to about 20 inch-ounces. It has,
however, been a challenge to develop a reliable disposable driver
capable of imparting higher torques for larger applications.
[0011] Power tools are used for some applications in the medical
industry. Such power tools can provide torque to a workpiece while
also providing higher rotational rates than can be provided with
manually driven tools. Torque-limiting systems can be utilized with
medical power tools, either as an additional attachment provided
in-line between the power tool and the workpiece or as internalized
systems within the power tool itself. Reusable torque-limiting
systems need to be sterilized between uses and typically must be
serviced and recalibrated periodically to ensure performance within
specifications. Disposable torque-limiting systems are an
alternative to the reusable systems. Once the torque-limiting
system has been used, it is discarded.
[0012] Disposable torque-limiting devices which are inexpensive for
use with power tools can fall out of specification with increased
RPMs and as such fail to perform sufficiently.
[0013] Thus there is a need for disposable torque-limiting systems
that can be utilized with medical power tools to limit applied
torque at higher rotational speeds and remain in specification over
a predetermined number of actuations. The disclosure is directed to
these and other important needs.
DISCLOSURE
[0014] Aspects of exemplars of torque-limiting devices, methods and
mechanisms are disclosed herein, in some exemplars a generally
hollow cylindrical body with a partially closed distal end provides
an upper shank formed inside the partially closed distal end of the
cylindrical body; a circumferential rim is formed on the outside of
the partially closed dial end; an upper torque-limiting interface
is formed on the inside of the partially closed distal end having
an axial bore; a lower shank component is placed in the body and
free to rotate axially, it further comprises a proximal end, a
distal end, a neck extending from the distal end, a drive socket
fluidly connecting the proximal end and the distal end, and a lower
torque-limiting interface disposed on the proximal end, wherein the
upper shank component and the lower shank component are aligned
along an axis in the direction of the axial bore and the drive
socket with the first torque-limiting interface in contact with the
second torque-limiting interface; an MBWA placed above the lower
shank on at least partially around the neck configured to apply
compressive force (F) along the axis to compress the first
torque-limiting interface against the second torque-limiting
interface; a tool collar with a flange extending radially therefrom
with a front on one side of the flange, a square leg formed on the
opposite of the flange and a shaped channel therethrough is
rotatably fit into the circumferential rim; a tool shaft with a
threaded back portion and a front end having a tool channel
therein; catches are formed on the tool shaft configured to mate
with the shaped channel whereby the tool shaft can be inserted
through the tool collar but rotate within the shaped channel; a
threaded retaining member is configured to engage the threaded back
portion; and wherein the tool shaft and threaded retaining member
cooperate to apply a predetermined force to the lower and upper
shanks, (the two interfaces together form a torque limiting
engagement), by mounted the tool shaft through the tool collar, the
axial bore, the drive socket and the MBWA and affixing the
retaining member thereto.
[0015] In some instances in the above exemplars the MBWA is
configured to apply compressive force (F) along the axis to
compress the first torque-limiting interface against the second
torque-limiting interface; the upper shank component and the lower
shank component are configured to engage to rotate together when
torque is applied to the lower shank component via the drive
socket; and, the upper shank component and the lower shank
component are configured to disengage when a predetermined torque
limit is exceeded.
[0016] In some instances the above exemplars further comprise a
plastic high lubricity washer between the flange and the
circumferential rim. In yet other instances the exemplars include a
roller bearing washer between the flange and the circumferential
rim.
[0017] Disclosed is a novel disposable torque-limiting device with
one or more of a torque limiting interface, a drive assembly with
reduced components, a shaped washer force assembly with reduced
components, simple assembly, operation for a limited predetermined
number of cycles at high speed. Cycles are a measure of the life
time of the disposable device.
[0018] Aspects of exemplars of torque-limiting devices, methods,
and mechanisms are disclosed herein, in some exemplars a generally
hollow cylindrical body with a partially closed distal end provides
an upper shank formed inside the partially closed distal end of the
cylindrical body; a circumferential rim is formed on the outside of
the partially closed dial end; an upper torque-limiting interface
is formed on the inside of the partially closed distal end having a
axial bore; a lower shank component having a proximal end, a distal
end, a retaining cavity formed thereon, a drive socket fluidly
connecting the proximal end and the distal end, and a lower
torque-limiting interface disposed on the proximal end, wherein the
upper shank component and the lower shank component are aligned
along an axis in the direction of the axial bore and the drive
socket with the first torque-limiting interface in contact with the
second torque-limiting interface; an MBWA placed above the lower
shank on at least partially around the neck configured to apply
compressive force (F) along the axis to compress the first
torque-limiting interface against the second torque-limiting
interface; a tool collar with a flange extending radially therefrom
with a front on one side of the flange, a square leg formed on the
opposite of the flange and a shaped channel therethrough is
rotatably fit into the circumferential rim; a tool shaft with a
threaded back portion and a front end having a tool channel
therein; catches are formed on the tool shaft configured to mate
with the shaped channel whereby the tool shaft can be inserted
through the tool collar but rotate within the shaped channel; a
threaded retaining member is configured to engage the threaded back
portion; and wherein the tool shaft and threaded retaining member
cooperate to apply a predetermined force to the lower and upper
shanks, (and the two interfaces together form a torque limiting
engagement), by mounted the tool shaft through the tool collar, the
axial bore, the drive socket and the MBWA and affixing the
retaining member thereto.
[0019] In some instances in the above exemplars the MBWA is
configured to apply compressive force (F) along the axis to
compress the first torque-limiting interface against the second
torque-limiting interface; the upper shank component and the lower
shank component are configured to engage to rotate together when
torque is applied to the lower shank component via the drive
socket; and, the upper shank component and the lower shank
component are configured to disengage when a predetermined torque
limit is exceeded.
[0020] In some instances the above exemplars further comprise a
plastic high lubricity washer between the flange and the
circumferential rim. In yet other instances the exemplars include a
roller bearing washer between the flange and the circumferential
rim. In some instances the above exemplars further comprise a tool
in the tool channel.
[0021] In some instances in the above exemplars the first
torque-limiting interface has a first plurality of undulations
arranged around the axial bore and separated by a first plurality
of transition regions; the second torque-limiting interface
comprises a second plurality of undulations arranged around the
drive socket and separated by a second plurality of transition
regions, the first and second pluralities being equal in number;
and each undulation comprises an upslope, a peak, and a
downslope.
[0022] In some instances in the above exemplars of the
torque-limiting device each upslope has an inclination angle
between about 3 degrees and about 15 degrees.
[0023] In some instances in the above exemplars of the
torque-limiting device each upslope has an inclination angle
between about 5 degrees and about 9 degrees.
[0024] In some instances in the above exemplars of the
torque-limiting device each upslope has an inclination angle
between about 6 degrees and about 8 degrees.
[0025] In some instances in the above the predetermined torque
limit is between about 0.1 Newton-meters and 3.0 Newton-meters. In
some instances in the above exemplars the predetermined torque
limit is between about 3.0 Newton-meters and 6.0 Newton-meters.
[0026] In some instances in the above exemplars of the
torque-limiting device the first torque-limiting interface and
second torque-limiting interface each comprise between two and five
undulations. In some instances in the above exemplars of the
torque-limiting device the first torque-limiting interface and
second torque-limiting interface each comprise three
undulations.
[0027] In some instances in the above exemplars of the
torque-limiting device the disposable torque limiting device is a
generally hollow cylindrical body with a partially closed distal
end; an upper shank formed inside the partially closed distal end
of the cylindrical body; a circumferential rim formed on the
outside of the partially closed dial end; an upper torque-limiting
interface having undulations formed on the inside of the partially
closed distal end having a axial bore; a lower shank component
rotatable placed within the cylindrical body comprising a proximal
end, a distal end, a retaining cavity formed thereon, a drive
socket fluidly connecting the proximal end and the distal end, and
a lower torque-limiting interface having undulations disposed on
the proximal end, wherein the upper shank component and the lower
shank component are aligned along an axis in the direction of the
axial bore and the drive socket with the first torque-limiting
interface in contact with the second torque-limiting interface; an
MBWA placed above the lower shank inside the retaining cavity
configured to apply compressive force (F) along the axis to
compress the first torque-limiting interface against the second
torque-limiting interface at a predetermined torque limit; a tool
collar with a flange extending radially, a front on one side of the
flange, a square leg formed on the opposite of the flange and a
shaped channel there through rotatably fit into the circumferential
rim; a tool shaft with a threaded back portion and a front end
having a tool channel therein; catches formed on the tool shaft
configured to mate with the shaped channel whereby the tool shaft
can be inserted through the tool collar but rotate within the
shaped channel; and a threaded retaining member configure to engage
the threaded back portion.
[0028] In some instances each undulation is a complex shaped wave
which limits degradation of inexpensive plastic materials and
provides nominal torque.
[0029] In some instances the first section of each undulation with
a higher shoulder near the center of the shank and a slope downward
to the perimeter of the shank; a second section having a wide
plateau; a third section having a plateau wider than the second
section; a fourth section having a plateau with height greater than
all other section; and a fifth section forming a sloped transition
region.
[0030] In some instances in the above exemplars of the
torque-limiting device the torque-limiting mechanism provides a
predetermined torque between about 0.1 Newton-meter and about 6.0
Newton-meters of torque at a rotational speed between about 50 RPM
and about 1300 RPM over at least one of 5, 10, 20, 30, 40, 50, 60,
70, 80, 90, 100, 105, 110, 120, 150, 180, 200, 220, 250, 300, 350,
400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000,
1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550,
1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, 2000, 2100, 2200,
2300, 2400, or 2500 actuations while remaining within a specified
operational range.
DRAWINGS
[0031] The above-mentioned features of the present disclosure will
become more apparent with reference to the following description
taken in conjunction with the accompanying drawings wherein like
reference numerals denote like elements. In addition, the drawings
are not necessarily drawn to scale. In the drawings:
[0032] FIG. 1A shows an exploded assembly perspective view back to
front of some aspects of an in-line torque limiting device of the
present disclosure.
[0033] FIG. 1B shows a cutaway front view of some aspects of an
in-line torque limiting device of the present disclosure.
[0034] FIG. 1C shows an exploded assembly perspective view front to
back of some aspects of an in-line torque limiting device of the
present disclosure.
[0035] FIGS. 1D and 1E show side views of biasing assembly
arrangements.
[0036] FIG. 2 shows an exploded assembly perspective view back to
front of some aspects of a torque limiting device of the present
disclosure.
[0037] FIG. 3 shows an exploded assembly perspective view of some
aspects of torque-limiting mechanisms of the present
disclosure.
[0038] FIG. 4A shows a perspective view of some aspects of
components of torque-limiting mechanisms of the present
disclosure.
[0039] FIG. 4B shows a top view of the upper shank of FIG. 4A.
[0040] FIGS. 4C-4G show cut-away sectional views of FIG. 4B from
line A-A to line E-E respectively.
[0041] FIG. 5 shows a perspective view of some aspects of
components of torque-limiting mechanisms of the present
disclosure.
[0042] FIG. 6A shows a top view of some aspects of components of
torque-limiting mechanisms of the present disclosure.
[0043] FIGS. 6B-6F show cut-away sectional views along the sections
marked A-A, B-B, C-C, D-D, and E-E in FIG. 4A.
[0044] FIGS. 7A and 7B show perspective views of some aspects of
components of torque-limiting mechanisms of the present disclosure.
FIG. 7C shows a side view of some aspects of components of
torque-limiting mechanisms of the present disclosure. The distal
end 102 of the lower shank is visible. The open top 105 of the
annular wall forming retaining cavity 103 is also visible. FIG. 7D
shows a cut-away section view along the section marked F-F in FIG.
7C.
[0045] FIGS. 8A and 8B show testing data from testing of an
implementation of the torque-limiting mechanisms of the present
disclosure.
[0046] FIG. 8C shows testing data from testing of a prior art
torque-limiting mechanism.
[0047] FIG. 8D shows testing data from testing of an implementation
of the torque-limiting mechanisms of the present disclosure.
[0048] As shall be appreciated by those having ordinary skill in
the art, the figures are not to scale, and modifications to scale
within a figure or across the figures are considered within the
present disclosure. All callouts in Figures are hereby incorporated
by this reference as if fully set forth herein.
FURTHER DISCLOSURE
[0049] Aspects of torque-limiting drivers are provided in exemplary
implementations of this disclosure. Those of ordinary skill in the
art will recognize small design variations that are within the
scope of this disclosure. The identification of some aspects and
not others shall not be considered limiting in the disclosure but
may be limitations in claims.
[0050] FIGS. 1A-1E illustrate aspects of implementations of
torque-limiting in-line drivers 10. FIGS. 2-7D illustrate
additional aspects of torque limiting drivers including operation
of the torque limiter.
[0051] The driver has a generally cylindrical shape with a cup
shaped drive cap 12 with connector mount or other structure to
facilitate use by a user. In some instances the drive cap may
support or be connected to a handle or other finger fold to allow
manual rotation of the device. For example, the drive cap is
affixed to a generally hollow cylindrical body 14. The cap 12 is
mated to the cylindrical body at the proximal end 15 of the
cylindrical body. The cap 12 may be snap-fitted to cylindrical body
14, or may be welded, adhered, or attached by any equivalent
thereof.
[0052] The hollow cylindrical body 14 has an open distal end 16
with a circumferential rim 17 on the exterior therein proving a
seat and guide for a tool collar 20. A lower shank 100 is fit
inside the body 14. The lower shank is generally cylindrical of a
size to allow to rotate axially within the body. Opposite the
circumferential rim on the interior 18 of the cylindrical body 14
is an upper shank component 200 formed as part of the cylindrical
hollow body 14 with at least an axial bore 210 and a upper or
second torque-limiting interface 250 disposed on the inside of the
cylindrical body 14.
[0053] The tool collar is formed of plastic and is a guide for a
shaft. The tool collar 20 has a flange 22 extending radially of a
size and shape to fit rotatably into the circumferential rim 17.
The tool collar has a roughly square leg 25 extending on one side
of the flange 22 and a nose 27 extending on the opposite of the
flange. A shaped channel 29 passes through the tool collar thereby
forming a fluid connection.
[0054] During assembly the lower shank component 100 fits movably
within the hollow body 14. The lower shank has a drive shaft 110
therethrough. On one side of the lower shank there is a lower or
first torque-limiting interface 150 and the other side of the lower
shank 100 may include a retaining cavity 103 configured to retain
biasing elements, such as a grouping of belleville washers, also
known as a coned-disc spring, hereinafter referred to as Multiple
Belleville Washer Assembly ("MBWA") 70 with a fluid passage 72
through the center of member. Each washer member 73 has a base 74
and a cone 75 and they are set in pairs alternating with base 74 to
base 74 and cone 75 to cone 75 with a fluid passage 72
therethrough. In other instances the washer members 73 are stacked
as shown in FIG. 1E. A flat washer 36A and 36B are placed on either
end of the stack of washer members 73. In some implementations,
compressible materials with durometer ratings between about 50
durometer and 100 durometer are used, within an annular wall 104. A
tool shaft 31 fits firmly into the tool collar channel 29. The tool
shaft may be partially hollow with an open front end 31. One or
more catches 33 are formed on a portion of the tool shaft whereby
the catches mate with the channel 29 and the tool shaft 32 is
restricted from rotation within the channel 29. The catches are
depicted as one or more flat sides in FIGS. 1A-1C. A tool channel
34 extends axially, at least partially, in the tool shaft from the
front end 31 of the tool shaft. A series of threads 35 are formed
on a back portion of the tool shaft 32. Optionally a first washer
36 is interposed between the flange and circumferential rim 17. The
washer is formed of plastic and has high lubricity. In some
instances depending on design requirements and use a flat roller
bearing washer 36' between a first washer 36C and a second washer
36D may be used with or in place of the washer 36. At higher speed
the roller bearing washer reduces frictional forces at the
circumferential rim 17. Aspects of the method of in-line torque
application at predetermined forces include reducing or eliminating
melting of the circumferential rim during the life time of the
device.
[0055] The lower shank 100 is inserted into the body 14 through the
proximal end 15 and the lower torque-limiting interface 150 sits on
the upper torque-limiting interface 250 and the two interfaces
together form a torque limiting engagement. The lower shank is
generally cylindrical of a size to allow to rotate axially within
the body. The square leg and tool shaft extends through the axial
bore 210 and the drive shaft 110. Formed as part of the drive shaft
110 are a series of drive catches 115 which mate with the square
legs 25 whereby when the lower shank 100 rotates the square leg
rotates as does any tools and the affixed therein.
[0056] A threaded 37 retaining member 38 such as a nut or other
fixture fits onto the threads 35 of the tool shaft and is used to
compress the MBWA 70 against the lower shank and hold the
components inside the device inline. Optionally, a washer 39 may be
placed between the MBWA 70 and retaining member 38. This engagement
provides a locking mechanism for tool shaft 32 relative to the body
14 via lower shank 100 when pressure is applied across lower shank
100 and upper shank 200. A preselected force is applied across
lower shank 100 and upper shank 200 via MBWA 70 within cylindrical
body 14. To seal the device, at the end of the drive cap 12 is the
connector mount 13 shown formed on the drive cap. The connector
mount 13 provides a fixation of a back drive shaft 42 for a powered
in-line torque limited driver (not shown).
[0057] In operation the drive shaft 40 which has a workpiece
engaging tip 41 is connected via the tip to a workpiece, fastener,
or other fixture that requires rotation for application. The
application of a rotational force to the device causes the first
torque-limiting interface 150 and the second torque-limiting
interface 250 (collectively referred to as the torque limiter)
support on the shanks to engage and rotate the tool until such time
as the amount of force necessary to rotate the tool further is
exceeded by the force the tool is experiencing during operation. At
that point the torque-limiter disengages and one of the first and
second torque-limiting interfaces move over the other as opposed to
with each other. When rotating a torque limiting assembly within a
plastic body with an attachment at the circumferential rim the
plastic body will tend to melt if sufficient frictional forces are
applied.
[0058] In FIG. 2, aspects and variations of assembly of a
torque-limiting device are shown. The driver has a generally
cylindrical shape with a cup shaped drive cap 12 with connector
mount or other structure to facilitate use by a user. For example,
the drive cap is affixed to a generally hollow cylindrical body 14.
The cap 12 is mated to the cylindrical body at the proximal end 15
of the cylindrical body. The cap 12 may be snap-fitted to
cylindrical body 14, or may be welded, adhered, or attached by any
equivalent thereof.
[0059] The hollow cylindrical body 14 has an open distal end 16
with a circumferential rim 17 on the exterior therein proving a
seat and guide for a tool collar 20. A lower shank 100 is fit
inside the body 14. Opposite the circumferential rim on the
interior 18 of the cylindrical body 14 is an upper shank component
200 formed as part of the cylindrical hollow body 14 with at least
an axial bore 210 and a torque-limiting interface 250 disposed on
the inside of the cylindrical body 14.
[0060] The tool collar is a guide for a shaft. The tool collar has
a flange 22 extending radially of a size and shape to fit rotatably
into the circumferential rim 17. The tool collar has a roughly
square leg 25 extending on one side of the flange 22 and a nose 27
extending on the opposite of the flange. A shaped channel 29 passes
through the tool collar thereby forming a fluid connection.
[0061] During assembly the lower shank component 100 fits movably
within the hollow body 14. The lower shank has a drive shaft 110
therethrough. On one side of the lower shank lower torque-limiting
interface 150 and the other side of the lower shank 100 is a
retaining cavity 103 which provides a volume to hold the MBWA 70
configured to position biasing elements, such as a MBWA 70. A tool
shaft 32 fits firmly into the tool collar channel 29. The tool
shaft may be partially hollow. One or more catches 33 are formed on
a portion of the tool shaft whereby the catches mate with the
channel 29 and the tool shaft 32 is restricted from rotation within
the channel 29. The catches are depicted as one or more flat sides
in FIGS. 1A-1C. A tool channel 34 extends axially, at least
partially, in the tool shaft. A series of threads 35 are formed on
a portion of the tool shaft 32. A first washer 36C, a second washer
36D, and a flat roller bearing washer `36 is interposed between the
flange and circumferential rim 17.
[0062] The lower shank 100 is once inserted into the body 14
through the proximal end 15 and the lower torque-limiting interface
150 sits on the upper torque-limiting interface 250. The square leg
and tool shaft extends through the axial bore 210 and the drive
shaft 110. Formed as part of the drive shaft 110 are a series of
drive catches 115 which mate with the square legs 25 whereby when
the lower shank 100 rotates the square leg rotates as does any
tools 40 affixed therein.
[0063] The threaded 37 retaining member 38 such as a nut or other
fixture fits onto the threads 35 of the tool shaft and is used to
compress the MBWA 70 against the lower shank and hold the
components inside the device inline. This engagement provides a
locking mechanism for tool shaft 32 relative to the body 14 via
lower shank 100 when pressure is applied across lower shank 100 and
upper shank 200. A preselected force is applied across lower shank
100 and upper shank 200 via MBWA 70 within cylindrical body 14. To
seal the device, the drive cap is mounted thereon. At the end of
the drive cap 12 is formed a handle 44 for manual use. The MBWA in
the manual device preferably provides a force of between about 5
N-m and about 13 N-m.
[0064] FIGS. 3, 4A-3G, and 5 show some additional details and
aspects of some implementations of torque-limiting mechanisms of
the present disclosure. The torque-limiting mechanisms have the
upper shank component 200, the lower shank component 100, and a
biasing coil spring configured to apply a force (F) along an axis
50. Upper shank component 200 can have a proximal end 201, a distal
end 202, an axial bore 210 connecting the proximal end and the
distal end, and a torque-limiting interface 250 disposed on the
proximal end. Lower shank component 100 can have a proximal end
101, a distal end 102, a drive socket 110 connecting the proximal
end and the distal end, and a torque-limiting interface 150
disposed on the proximal end. The upper shank component and the
lower shank component are aligned along an axis 50 in the direction
of the axial bore 210 and the drive socket 110 with the
torque-limiting interface 250 in contact with the torque-limiting
interface 150. The biasing element is configured to apply a
compressive force (F) along the axis to compress the
torque-limiting interface against the torque-limiting interface.
The upper shank component 200 and the lower shank component 100 are
configured to engage to generally nest with each other and rotate
together when torque is applied to the lower shank component via
the drive socket and are configured to disengage when a
predetermined torque limit is exceeded. When disengaged, the
torque-limiting interfaces 150/250 slide past each other in
relative rotation about the axis 50. Drive socket 110 can have any
suitable shape that allows for the transmission of torque to the
lower shank component 100. Suitable shapes for the drive socket 110
include geometric shape profiles such as hexagons, squares, or
truncated/rounded versions thereof.
[0065] Those of ordinary skill in the art can appreciate that the
torque-limiting mechanisms of the present disclosure can be
incorporated into any systems or devices that require
torque-limited rotation between subcomponents of those systems or
devices. In some implementations, the torque-limiting mechanisms of
the present disclosure can be incorporated into torque-limited
drivers for use in surgical applications; such drivers can be
hand-driven or driven with power tools at higher rates of
rotation.
[0066] FIGS. 4A-4G and 5 show further aspects of some
implementations. Upper shank component 200 can have a
torque-limiting interface 250 with a plurality of undulations 220
arranged around the axial bore and separated by a plurality of
transition regions 224. The lower shank component 100 can have a
torque-limiting interface 150 having a plurality of undulations 120
arranged around the drive socket and separated by a plurality of
transition regions 124, the first and second pluralities being
equal in number. Each undulation 120/220 can be formed as an
upslope 121/221, a peak 122/222, and a downslope 123/223.
[0067] The undulations 220 are not gears and are complex shaped
waves to balance maintaining nominal torque over a specific number
of actuations and limit degradation of inexpensive plastic
materials which form the undulations. Such materials will degrade,
overheat and/or melt and fail more quickly if subjected to
unnecessary friction caused by contact at the torque-limiting
interface 150. By shaping specific portions of an undulation 220 as
shown in sections A-A through E-E (see FIGS. 4B-4G) the balance of
sufficient performance at nominal torque versus degradation is
accomplished. Section A-A (FIG. 4C) has a higher shoulder near the
center 401 of the shank and a slope downward 402 to the perimeter
of the shank. Contact between the upper and lower shanks at this
section is minimized. This contact area is not the maximum torque
transfer area. Section B-B is a region of greater compressive force
and by spreading the higher load across a wider plateau 404 the
stress on the plastic shanks is distributed in this higher
compressive force region. Section C-C provides the widest plateau
406 to further distribute the compressive forces which increase as
the lower shank 100 moves around the upper shank 200 along the
direction of arrow 1000. Section D-D is the maximum height "H"
plateau 408 of the undulation and it is where the maximum
compressive forces are applied between shanks, it is a wide plateau
to distribute the load. Section E-E provides a transition region
wherein compressive forces are reduced and the area of is reduced
via a sloping region 410. Shaped undulations disclosed herein
maintain predetermined torque ranges without adding excessive wear
and heat to the assembly.
[0068] In some implementations, the torque-limiting interfaces
150/250 do not contain any step or drop-off greater than about
0.005''. One or more cutouts or slots (not shown) can be provided
in one or more of the upslopes, 121/221, peaks 122/222, or
downslopes 123/223 to collect at least a portion of any debris
generated during operation. In some embodiments, downslope 123/223
is designed with maximum length to provide the softest downward
angle back down to the initial height of the next upslope 121/221.
During powered rotation, a softer downslope mitigates degradation
of the downslope 123/223 material. Such degradation adversely
impact performance as the torque-limit at which disengagement
occurs can change as the material degrades.
[0069] Each undulation 120/220 sweeps through a portion of the 360
degrees around the central axial bore 210 or drive socket 11, with
the plurality of undulations 120/220 covering a total portion of
the 360 degrees around the central axial bore. In some
implementations, the total portion covered by the plurality of
undulations 120/220 can be at least about 65% of the 360 degrees
(about 235 degrees), at least about 70% of the 360 degrees (about
255 degrees), at least about 80% of the 360 degrees (about 285
degrees), at least about 83% of the 360 degrees (about 300
degrees), at least about 90% of the 360 degrees (about 324
degrees), at least about 95% of the 360 degrees (about 345
degrees), or at least about 98% of the 360 degrees (about 350
degrees). The portion not covered by the plurality of undulations
120/220 is filled with transition regions 124/224 between the end
of each downslope 123/223 and the beginning of the next upslope
121/221. Each transition region 124/224 can be selected to be no
greater than about 35 degrees, no greater than about 20 degrees, no
greater than about 15 degrees, no greater than about 10 degrees, no
greater than about 5 degrees, no greater than about 4 degrees, no
greater than about 3 degrees, no greater than about 2 degrees, no
greater than about 1 degree, or can be eliminated entirely if the
end of each downslope 123/223 is immediately adjacent to the
beginning of the next upslope 121/221.
[0070] A softer downslope angle the torque-limiting interfaces
150/250 can substantially mitigate or eliminate any "click" or
audible indication that the upper shank component 200 and lower
shank component 100 have slipped past each other during a
disengagement, also referred to herein as an actuation, when the
predetermined torque limit has been exceeded. In some
implementations, an actuation indicating system can be incorporated
in the overall torque-limiting driver to create one or more
"clicks" when the upper shank component 200 and lower shank
component 100 have slipped past each other. In some
implementations, the actuation indicating system can include a flag
feature on either lower shank component 100 or upper shank
component 200 that impacts one or more spokes, protrusions, or
other physical features on another component in the system as
relative rotation occurs.
[0071] Upper shank component 200 and lower shank component 100 can
be formed from various materials. Suitable materials include
stainless steels, aluminums, plastic materials, or composites
including plastic. Plastic and other economical equivalents improve
cost efficiency of production while providing high tensile
strength, resistance to deformation, etc. Effective materials
include plastics, resins, polymers, imides, fluoropolymers,
thermoplastic polymers, thermosetting plastics, and the like as
well as blends or mixtures thereof. In some implementations, 30%
glass-filled polyetherimide can be used to form one or more of the
above components. For components formed from stainless steels or
aluminums, the shank components can be heat treated, passivated, or
anodized via suitable methods known to those of ordinary skill in
the art. In some implementations, aluminum shank components can be
finished with a hard anodize finish per MIL-A-8625F, type III,
class 2. In some implementations, stainless steel 440c shank
components can be heat treated per AMS 2759/5D to 58Rc and
passivated with treatment with nitric acid and/or sodium
dichromate. Other heat treatments and passivation methods known in
the art are also suitable. In some implementations, corresponding
pairs of gear rings are formed from different materials. In some
preferred implementations, one shank component 100/200 is formed
from stainless steel or aluminum and the corresponding gear ring is
formed from 30% glass-filled polyetherimide (PEI) resin. In some
implementations the shank components 100/200 can be made from the
same material.
[0072] According to aspects of one or more exemplary
implementations, components of the torque-limiting mechanisms of
the present disclosure are resistant to sterilization, cleaning,
and preparation operations. For example, the upper shank component
and lower shank component may be configured to withstand
sterilization by methods including radiation (e.g., gamma rays,
electron beam processing), steam (e.g., autoclave), detergents,
chemical (e.g., Ethylene Oxide), heat, pressure, inter alia. For
example, materials may be selected according to resistance to one
or more selected sterilization techniques.
[0073] The material selection and surface treatments applied to the
torque-limiting interfaces 150/250 can affect the predetermined
torque limit. The static friction between the torque-limiting
interfaces 150/250 determines when disengagement will occur, as the
rotation force can overcome the static friction holding the
interfaces into engagement with each other. Greater contact surface
area of the opposing interfaces, via wider undulations 120/220 or
other aspects of the shape/profile of the undulations 120/220, will
increase the resistance to actuation and lead to a higher
predetermined torque limit.
[0074] In some preferred implementations, upper shank component 200
and lower shank component 200 are both mad from 30% glass-filled
polyetherimide (PEI) resin. In some implementations, a glass-filled
ULTEM.RTM. PEI from Saudi Basic Industries Corporation (SABIC) can
be used to form the upper shank component 200 and lower shank
component 200 via machining or molding. In some implementations, a
lubricant is disposed on one or both of torque-limiting interfaces
150/250. Such lubricants are useful to avoid excessive heat
build-up during actuations at high rates of rotation, which can
melt or degrade the PEI material.
[0075] The shape of some implementations of undulations 120/220 can
be seen in FIGS. 6A-6F. FIG. 6A shows a top view of the
torque-limiting interface 150 at the proximal end 201 of upper
shank component 200. FIG. 6B shows a cut-away view of the upper
shank component 200 along line A-A shown in FIG. 6A. FIG. 6C shows
a cut-away view of the upper shank component 200 along line B-B
shown in FIG. 6A. FIG. 6D shows a cut-away view of the upper shank
component 200 along line C-C shown in FIG. 6A. FIG. 6E shows a
cut-away view of the upper shank component 200 along line E-E shown
in FIG. 6A. FIG. 6F shows a cut-away view of the upper shank
component 200 along line D-D shown in FIG. 6A. The number of
undulations 120/220 is determined by the size of the upper shank
component 200 and lower shank component 100 and the shape of the
undulations 120/220. The size of the shank components 100/200
determines the functional path length that the plurality of
undulations may have. The functional path length refers to the
circumferential length of a circular path along the midpoint of the
undulations, shown as a dashed circle 227 in FIG. 6A. A larger
diameter shank component allows for a larger functional path
length. The shape of the undulations 120/220 refers to the
inclination angle of the upslope 121/221, the length of the peak
122/222, and the declination angle of the downslope 123/223.
Sharper inclination and declination angles and shorter peak lengths
can lead to a shorter functional path length for each individual
undulation, which would allow for more undulations to be placed
onto the torque-limiting interfaces 150/250. The torque-limiting
interfaces may have two undulations, three undulations, four
undulations, or five or more undulations. Three or more undulations
are used in some preferred implementations, as systems with only
two undulations may be less stable during actuations at higher
rates of rotation.
[0076] The width of the undulations can span the entirety of the
annular ring of the proximal ends of the upper shank component and
lower shank component between the drive socket 110 or axial bore
210 and outer edges of those components, or can be reduced widths
to accommodate adjoining parts to avoid undesired contact points or
friction. The width must be sufficient to provide adequate
interface contact area with the opposing set of waves to create the
friction necessary for torque transmission. Larger widths allow for
the applied force to be distributed over larger surface areas and
reduce stress on the components.
[0077] The inclination angle of each upslope 121/221 can be about 3
to about 15 degrees, more preferably about 5 to about 9 degrees,
more preferably about 6 to about 8 degrees, and most preferably
about 7 degrees. The inclination angle is measured along the
functional path length along the midpoint of the undulations, as
the angle along the interior edge 126/226 will be higher due to the
shorter path length, and the angle along the exterior edge 125/225
will be lower due to the longer path length. The declination angle
of each downslope 123/223 can be about 5 to about 45 degrees, more
preferably about 10 to about 30 degrees, more preferably about 10
to about 20 degrees, and most preferably about 15 degrees. The
declination angle is measured along the functional path length
along the midpoint of the undulations. In some preferred
implementations, the ratio of the functional path length of the
upslope 121/221 of each undulation to the functional path length of
the downslope of each undulation can be about 3.0:1, about 2.5:1,
about 2.4:1, about 2.3:1, about 2.2:1, about 2.1:1, about 2.0:1,
about 1.9:1, about 1.8:1, about 1.7:1, about 1.6:1, about 1.5:1,
about 1.4:1, about 1.3:1, about 1.2:1, about 1.1:1, or about 1.0:1.
In some preferred implementations the ratio can be between about
2.2:1 and about 1.8:1, or more preferably about 2.0:1.
[0078] Each peak 122/222 has an even height across its surface from
the interior edge 126/226 to the exterior edge 125/225 at each
radial line from the central axis of the respective shank component
100/200. In some implementations the functional path length of each
peak 122/222 is approximately equal to the length of each of the
transition regions 124/224, such that the peaks 122/222 of each
torque-limiting interface are complementary and mate with the
transition regions 124/224 of the opposing torque-limiting
interface.
[0079] FIGS. 7A-7D show some aspects of an implementation of a
lower shank component 100 the present disclosure. FIG. 7A and FIG.
7B show perspective views of an implementation of a lower shank
component 100. FIG. 7C shows a side view while FIG. 7D shows a
cross-sectional view along the line D-D shown in FIG. 7C. The lower
shank component 100 can include a retaining cavity 103 configured
to retain biasing element within an annular wall 104 located at the
distal end 102. The retaining cavity 103 provides for a volume in
which a biasing element 300 can be compressed, so that if biasing
element 300 expands radially during compression it will be retained
within retaining cavity 103 rather than impinging or contacting
other components within the system.
[0080] Biasing element provides compressive force between the upper
shank component and lower shank component to place the
torque-limiting interfaces 150/250 into frictional contact with
each other. Suitable biasing elements can include springs, spring
washers, also referred to as Belleville washers, grommets or
washers of compressible materials such as rubber. In some
implementations, compressible materials with durometer ratings
between about 50 durometer and 100 durometer can be used as biasing
elements. The biasing element can be compressed by other components
in a torque-limiting driver. The amount of compression applied to a
biasing element can be used to set the predetermined torque limit
at which disengagement/actuation of the torque-limiting mechanism
occurs. Higher compressive forces created by the biasing element
will create higher predetermined torque limits.
[0081] According to aspects of one or more exemplary
implementations, the torque-limiting mechanisms of the present
disclosure are capable of imparting torques of up to about 6 N-m at
various rotational speeds. For example, the torque output range may
be selected between about 0.5 N-m and about 6 N-m and utilized in
combination with a rotational speed selected between about 150 RPMs
and about 1300 RPMs. Typically, the torque requirement is different
for different operations and for different implants. For example,
applications may include those in the field of orthopedic surgery,
construction and emplacement of implants, etc. In such instances,
the predetermined torque limit may be about 6 N-m, depending on an
implant's specifications. Smaller fasteners may utilize lower
torque limits between about 0.1 N-m and about 2.0 N-m. In some
instances the torque-limiting mechanisms of the present disclosure
will provide a predetermined torque of at least one of 0.1, 0.2,
0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5,
1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8,
2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1,
4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4,
5.5, 5.6, 5.7, 5.8, 5.9, or 6.0 Newton-meters (N-m) of torque at a
rotational speed of at least one of 50, 100, 150, 200, 250, 300,
350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950,
1000, 1050, 1100, 1150, 1200, 1250, or 1300 RPMs over at least one
of 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 105, 110, 120, 150,
180, 200, 220, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700,
750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300,
1350, 1400, 1450, 1500, 1550, 1600, 1650, 1700, 1750, 1800, 1850,
1900, 1950, or 2000 actuations while remaining within a specified
operational range.
[0082] FIGS. 6A and 6B show testing data of an implantation of a
torque-limiting mechanism of the present disclosure. A
torque-limiting driver that incorporated a torque-limiting
mechanism having the torque-limiting interfaces shown in FIGS. 2,
3, and 6A-6F formed from 30% glass-filled PEI resin was assembled
and tested at 450 RPM with a predetermined torque limit of about
1.05 N-m. The torque-limiting driver was rotated at 450 RPM for 1
second intervals and the torque output was measured with an
electronic torque transducer. FIG. 8A shows that the torque limit
remained within an operational range of about 0.9 to about 1.1 N-m
over approximately 2,200 actuations. FIG. 8B shows data for two
1-second intervals and shows the actuations that occur over those
1-second intervals. Approximately 22 actuations, from 7.5
revolutions per second at 450 RPM, occur in each 1-second interval,
with the applied torque remaining within the operational range.
[0083] FIGS. 8C and 8D show the torque output profiles of
torque-limiting drivers over a single hand-driven actuation. FIG.
8C shows the torque profile of a traditional crown gear interface
with opposing sets of jagged teeth, such as that disclosed in U.S.
Pat. No. 7,938,046, incorporated herein in its entirety for all
purposes. The resulting profile shows a spike drop-off in torque as
the opposing teeth slip off each other sharply. Systems
incorporating these jagged teeth crown gears exhibit inconsistent
torque-limits across ranges of rotational speeds, with higher
rotational speeds showing higher torque. In contrast, FIG. 6D shows
a torque output profile from the system used in FIGS. 6A and 6B,
which incorporates the three-undulation torque-limiting interfaces
shown in FIGS. 2, 3, 4A-4F and described more fully elsewhere
herein. The torque output increases and decreases more gradually
and smoothly through each actuation, which provides for a more
consistent torque-limit across rotational speeds, including higher
rotational speeds up to 1300 RPM. Further, the torque-limiting
mechanisms are more durable and can last through a higher number of
actuations, including over 2,000 actuations, while remaining within
a specified operational range.
[0084] While the method and agent have been described in terms of
what are presently considered to be the most practical and
preferred implementations, it is to be understood that the
disclosure need not be limited to the disclosed implementations. It
is intended to cover various modifications and similar arrangements
included within the spirit and scope of the claims, the scope of
which should be accorded the broadest interpretation so as to
encompass all such modifications and similar structures. The
present disclosure includes any and all implementations of the
following claims.
[0085] It should also be understood that a variety of changes may
be made without departing from the essence of the disclosure. Such
changes are also implicitly included in the description. They still
fall within the scope of this disclosure. It should be understood
that this disclosure is intended to yield a patent covering
numerous aspects of the disclosure both independently and as an
overall system and in both method and apparatus modes.
[0086] Further, each of the various elements of the disclosure and
claims may also be achieved in a variety of manners. This
disclosure should be understood to encompass each such variation,
be it a variation of an implementation of any apparatus
implementation, a method or process implementation, or even merely
a variation of any element of these.
[0087] Particularly, it should be understood that as the disclosure
relates to elements of the disclosure, the words for each element
may be expressed by equivalent apparatus terms or method
terms--even if only the function or result is the same.
[0088] Such equivalent, broader, or even more generic terms should
be considered to be encompassed in the description of each element
or action. Such terms can be substituted where desired to make
explicit the implicitly broad coverage to which this disclosure is
entitled.
[0089] It should be understood that all actions may be expressed as
a means for taking that action or as an element which causes that
action.
[0090] Similarly, each physical element disclosed should be
understood to encompass a disclosure of the action which that
physical element facilitates.
[0091] Any patents, publications, or other references mentioned in
this application for patent are hereby incorporated by reference.
In addition, as to each term used it should be understood that
unless its utilization in this application is inconsistent with
such interpretation, common dictionary definitions should be
understood as incorporated for each term and all definitions,
alternative terms, and synonyms such as contained in at least one
of a standard technical dictionary recognized by artisans and the
Random House Webster's Unabridged Dictionary, latest edition are
hereby incorporated by reference.
[0092] In this regard it should be understood that for practical
reasons and so as to avoid adding potentially hundreds of claims,
the applicant has presented claims with initial dependencies
only.
[0093] Support should be understood to exist to the degree required
under new matter laws--including but not limited to United States
Patent Law 35 USC 132 or other such laws--to permit the addition of
any of the various dependencies or other elements presented under
one independent claim or concept as dependencies or elements under
any other independent claim or concept.
[0094] To the extent that insubstantial substitutes are made, to
the extent that the applicant did not in fact draft any claim so as
to literally encompass any particular implementation, and to the
extent otherwise applicable, the applicant should not be understood
to have in any way intended to or actually relinquished such
coverage as the applicant simply may not have been able to
anticipate all eventualities; one skilled in the art, should not be
reasonably expected to have drafted a claim that would have
literally encompassed such alternative implementations.
[0095] Further, the use of the transitional phrase "comprising" is
used to maintain the "open-end" claims herein, according to
traditional claim interpretation. Thus, unless the context requires
otherwise, it should be understood that the term "compromise" or
variations such as "comprises" or "comprising", are intended to
imply the inclusion of a stated element or step or group of
elements or steps but not the exclusion of any other element or
step or group of elements or steps.
[0096] Such terms should be interpreted in their most expansive
forms so as to afford the applicant the broadest coverage legally
permissible.
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