U.S. patent application number 12/846421 was filed with the patent office on 2010-12-23 for transmission and variable radially expanding spring clutch assembly.
This patent application is currently assigned to Black & Decker Inc.. Invention is credited to Kevin S. Agan, Thomas J. Bodine, Joao Norona, Barry E. Plato.
Application Number | 20100319474 12/846421 |
Document ID | / |
Family ID | 40430435 |
Filed Date | 2010-12-23 |
United States Patent
Application |
20100319474 |
Kind Code |
A1 |
Bodine; Thomas J. ; et
al. |
December 23, 2010 |
TRANSMISSION AND VARIABLE RADIALLY EXPANDING SPRING CLUTCH
ASSEMBLY
Abstract
A transmission generally includes a shaft member having a
continuous cylindrical surface portion longitudinally disposed next
to a cylindrical outer surface portion interrupted by longitudinal
grooves. A first gear assembly has a first clutch spring that holds
a first set of rolling members between lobes that extend from a
first output gear. A second gear assembly has a second clutch
spring that holds a second set of rolling members between lobes
that extend from a second output gear. The first gear assembly and
the second gear assembly are configured to move longitudinally
along the shaft member to a position where at least one of the
first gear assembly and the second gear assembly is engaged for
rotation with the shaft member when a value of torque at the shaft
member is below a torque threshold value.
Inventors: |
Bodine; Thomas J.;
(Glenwood, MD) ; Plato; Barry E.; (Bel Air,
MD) ; Agan; Kevin S.; (Fallston, MD) ; Norona;
Joao; (Baltimore, MD) |
Correspondence
Address: |
Harness Dickey & Pierce, P.L.C. (Stanley B&D)
P.O. Box 828
Bloomfield Hills
MI
48303
US
|
Assignee: |
Black & Decker Inc.
Newark
DE
|
Family ID: |
40430435 |
Appl. No.: |
12/846421 |
Filed: |
July 29, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11853435 |
Sep 11, 2007 |
7793560 |
|
|
12846421 |
|
|
|
|
Current U.S.
Class: |
74/333 |
Current CPC
Class: |
F16D 7/002 20130101;
F16D 43/208 20130101; F16H 3/32 20130101; Y10T 74/19242 20150115;
Y10T 74/19274 20150115; F16D 7/10 20130101; Y10T 74/19358 20150115;
F16H 35/10 20130101 |
Class at
Publication: |
74/333 |
International
Class: |
F16H 3/08 20060101
F16H003/08 |
Claims
1.-24. (canceled)
25. A transmission comprising: a shaft member having a continuous
cylindrical surface portion longitudinally disposed next to a
cylindrical outer surface portion interrupted by longitudinal
grooves; a first gear assembly having a first clutch spring that
holds a first set of rolling members between lobes that extend from
a first output gear; and a second gear assembly having a second
clutch spring that holds a second set of rolling members between
lobes that extend from a second output gear, wherein said first
gear assembly and said second gear assembly are configured to move
longitudinally along said shaft member to a position where at least
one of said first gear assembly and said second gear assembly is
engaged for rotation with said shaft member when a value of torque
at said shaft member is below a torque threshold value.
26. The transmission of claim 25, wherein said torque threshold
value is at least based on an angle between a surface of one of
said longitudinal grooves and a surface of one of said lobes of
said first output gear between which said first set of rolling
members is disposed such that when a value of said angle decreases,
said torque threshold value increases.
27. The transmission of claim 25, wherein said longitudinal grooves
define a curvature that varies longitudinally along said shaft
member.
28. The transmission of claim 25, wherein said first clutch spring
and said second clutch spring have different spring constants.
29. The transmission of claim 25, wherein said first clutch spring
includes helical coils that form a helical spring and wherein each
of said helical coils contacts a successive coil.
30. The transmission of claim 25, wherein said first clutch spring
includes helical coils that form a helical spring and wherein each
of said coils is spaced apart from each other.
31. The transmission of claim 30, wherein an end of said first
clutch spring is configured to contact a successive coil of said
helical coils.
32. The transmission of claim 25, wherein said first clutch spring
and said second clutch spring have spring constants that are
equal.
33. The transmission of claim 25, wherein said longitudinal grooves
are each substantially flat.
34. The transmission of claim 25, wherein a portion of said
longitudinal grooves has a curvature that defines at least one of a
plane, a v-shape, a radius, a ramp and one or more combinations
thereof.
35. The transmission of claim 25, wherein said first clutch spring
is an annular unitary sleeve around said rolling members and said
lobes of said first output gear.
36. A transmission comprising: a shaft member having a continuous
cylindrical surface portion longitudinally disposed next to a
cylindrical outer surface portion interrupted by longitudinal
grooves; and a first gear assembly having a first clutch spring
that holds a first set of rolling members between lobes that extend
from a first output gear, wherein said first gear assembly is
configured to move longitudinally along said shaft member to a
position where said first gear assembly is engaged for rotation
with said shaft member when a value of torque at said shaft member
is below a torque threshold value that is based on an angle between
a surface of one of said longitudinal grooves and a surface of one
of said lobes between which said first set of rolling members is
disposed such that when a value of said angle decreases, said
torque threshold value increases.
37. The transmission of claim 36 further comprising a second gear
assembly having a second clutch spring that holds a second set of
rolling members between lobes that extend from a second output gear
wherein said first gear assembly and said second gear assembly are
configured to move longitudinally along said shaft member to a
position where at least one of said first gear assembly and said
second gear assembly is engaged for rotation with said shaft
member.
38. The transmission of claim 36, wherein said longitudinal grooves
define a curvature that varies longitudinally along said shaft
member.
39. The transmission of claim 37, wherein said first clutch spring
and said second clutch spring have different spring constants.
40. The transmission of claim 36, wherein said first clutch spring
includes helical coils that form a helical spring and wherein each
of said helical coils contacts a successive coil.
41. The transmission of claim 36, wherein said first clutch spring
includes helical coils that form a helical spring and wherein each
of said coils is spaced apart from each other.
42. The transmission of claim 41, wherein an end of said first
clutch spring is configured to contact a successive coil of said
helical coils.
43. The transmission of claim 36, wherein a portion of said
longitudinal grooves has a curvature that defines at least one of a
plane, a v-shape, a radius, a ramp and one or more combinations
thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a division of U.S. Ser. No. 11/853,435
entitled "Transmission And Variable Radially Expanding Spring
Clutch Assembly" and filed Sep. 11, 2007, which is now U.S. Pat.
No. 7,793,560 issued on Sep. 14, 2010. The disclosure of the above
application is hereby incorporated by reference as if fully set
forth in detail herein.
FIELD
[0002] The present teachings relate to a radially expanding spring
clutch that can be used in a transmission to reduce torque
transmitted therethrough when a threshold torque is surpassed.
BACKGROUND
[0003] Certain types of drills and drivers can produce enough
torque through reduction gearing that manufacturers include an
overdrive clutch between the tool spindle and the motor. This is
done to avoid scenarios where the tool can overpower the user or a
component in the transmission of the tool could be damaged.
[0004] When a threshold torque is surpassed, the overdrive clutch
can open and reduce or eliminate the torque that is transmitted
through the clutch. By reducing the torque, the user can continue
to hold the tool and/or can avoid possible damage to the
transmission. Notwithstanding, the overdrive clutch can be
relatively large, it typically includes many components and can be
relatively complex. A relatively high part count and associated
complexity can add additional costs to the tool.
SUMMARY
[0005] The present teachings generally include a transmission that
includes a shaft member having a continuous cylindrical surface
portion longitudinally disposed next to a cylindrical outer surface
portion interrupted by longitudinal grooves. A first gear assembly
has a first clutch spring that holds a first set of rolling members
between lobes that extend from a first output gear. A second gear
assembly has a second clutch spring that holds a second set of
rolling members between lobes that extend from a second output
gear. The first gear assembly and the second gear assembly are
configured to move longitudinally along the shaft member to a
position where at least one of the first gear assembly and the
second gear assembly is engaged for rotation with the shaft member
when a value of torque at the shaft member is below a torque
threshold value.
[0006] Further areas of applicability will become apparent from the
description provided herein. It should be understood that the
description and specific examples are intended for purposes of
illustration only and are not intended to limit the scope of the
present teachings.
DRAWINGS
[0007] The drawings described herein are for illustration purposes
only and are not intended to limit the scope of the present
teachings.
[0008] FIG. 1 is a perspective view of an exemplary right angle
drill or driver constructed in accordance with the present
teachings.
[0009] FIG. 2 is a front view of an exemplary radially expanding
spring clutch constructed in accordance with the present
teachings.
[0010] FIG. 3 is an exploded assembly view of the radially
expanding spring clutch of FIG. 2 showing rolling members and a
shaft member with longitudinal grooves configured to receive the
rolling members in accordance with the present teachings.
[0011] FIG. 4 is a diagram of a cross-sectional view of the
radially expanding spring clutch of FIG. 2 in a drive condition and
a low torque condition (i.e., below a threshold torque value) in
accordance with the present teachings.
[0012] FIG. 5 is similar to FIG. 4 and shows the rolling members
leaving longitudinal grooves of a shaft member as torque increases
to just below a torque threshold value in accordance with the
present teachings.
[0013] FIG. 6 is similar to FIG. 5 and shows the rolling members
disposed on an outer cylindrical surface of the shaft member after
leaving the longitudinal grooves formed thereon, as a value of
torque at the shaft member has exceeded the torque threshold value
in accordance with the present teachings.
[0014] FIG. 7 is a diagram of a torque pathway through an exemplary
right angle drive transmission showing a low speed condition in
which a radially expanding spring clutch assembly is enabled (i.e.,
not bypassed) in accordance with the present teachings.
[0015] FIG. 8 is similar to FIG. 7 and shows a different torque
pathway through the right angle drive transmission illustrating a
high speed condition in which the radially expanding spring clutch
assembly is bypassed in accordance with the present teachings.
[0016] FIG. 9 is a diagram of a cross-sectional view of a radially
expanding spring clutch shown in a drive condition constructed in
accordance with additional aspects of the present teachings.
[0017] FIG. 10 is similar to FIG. 9 and shows the rolling members
leaving the longitudinal grooves formed on a clutch shaft and
stretching a clutch spring to form a generally elliptical shape in
accordance with the present teachings.
[0018] FIG. 11 is similar to FIG. 10 and shows the rolling members
disposed on the outer cylindrical surface of the clutch shaft in a
clutch out or reduced torque condition causing the clutch spring to
stretch and form a generally elliptical shape in accordance with
the present teachings.
[0019] FIG. 12 is a diagram of a cross-sectional view of a radially
expanding spring clutch having four rolling members disposed
between four lobes of a clutch gear with an exemplary unitary
clutch spring encircling the rolling members and the four lobes on
the clutch gear in accordance with further aspects of the present
teachings.
[0020] FIG. 13 is similar to FIG. 12 and shows an exemplary clutch
spring that can be a helical spring configured such that portions
of the coil are at an increasing radial distance from a shaft
member in accordance with yet further aspects of the present
teachings.
[0021] FIG. 14 is a diagram of a variable radially expanding spring
clutch having a first output gear that can be engaged to a shaft
member to provide a first gear ratio and a second gear that can be
disengaged from the shaft member in accordance with further aspects
of the present teachings.
[0022] FIG. 15 is similar to FIG. 14 and shows the first gear
disengaged and the second gear engaged to the clutch shaft to
provide a second gear ratio in accordance with the present
teachings.
[0023] FIG. 16 is similar to FIG. 14 and shows separate clutch
springs associated with the first and second gear assemblies
longitudinally spaced from one another in accordance with the
present teachings.
[0024] FIG. 17 is a diagram showing an angle and an associated
torque threshold value; the angle being defined between a surface
of the longitudinal grooves of the shaft member and a surface of
the lobes of a gear member in accordance with the present
teachings.
[0025] FIG. 18 is a perspective view of an exemplary shaft member
of a radially expanding spring clutch assembly showing longitudinal
grooves formed in one region of the shaft member and another region
with a reduced diameter continuous cylindrical portion in
accordance with the present teachings.
[0026] FIG. 19 is a perspective view of another exemplary shaft
member having longitudinal grooves whose curvature changes along a
longitudinal axis of the shaft member in accordance with further
aspects of the present teachings.
[0027] FIG. 20 is a diagram of a cross-sectional view of the clutch
shaft of FIG. 19 showing the curvature of the longitudinal grooves
being substantially flat in accordance with the present
teachings.
[0028] FIG. 21 is a diagram of a cross-sectional view of the shaft
member of FIG. 19 showing the curvature of the longitudinal grooves
in accordance with the present teachings.
[0029] FIG. 22 is similar to FIG. 21 and shows differing curvature
at a different longitudinal location along the shaft member
configured to produce a higher or lower torque threshold value in
accordance with the present teachings.
[0030] FIG. 23 is a diagram of a cross-sectional view of another
exemplary shaft member showing a curvature of longitudinal grooves
including a v-shaped configuration in accordance with the present
teachings.
[0031] FIG. 24 is a perspective view of an exemplary clutch spring
showing each of the helical coils separated from one another and
ends of the coils configured with a reduced cross-section in
accordance with the present teachings.
[0032] FIG. 25 is a perspective view of an exemplary clutch spring
showing each of the helical coils separated from one another and
ends of the coils configured in an open condition in accordance
with the present teachings.
[0033] FIG. 26 is a perspective view of an exemplary clutch spring
showing each of the helical coils separated from one another and
ends of the coils configured in a closed condition in accordance
with the present teachings.
DETAILED DESCRIPTION
[0034] The following description is merely exemplary in nature and
is not intended to limit the present teachings, their application
or uses. It should be understood that throughout the drawings,
corresponding reference numerals indicate like or corresponding
parts and features.
[0035] The present teachings generally pertain to a powered drill
or driver 10. In one aspect of the present teachings, the drill or
driver 10 can be a right angle drill 12, as shown in FIG. 1. The
right angle drill 12 can include a housing 14 having a handle 16
from which a trigger assembly 18 extends. A secondary handle 20 can
also extend from the housing 14 to provide, for example, an
additional hand hold for the user to hold the right angle drill
12.
[0036] The housing 14 can contain, for example, a motor 22 that can
drive a transmission 24 that ultimately provides a torque output to
a chuck assembly 26. The chuck assembly 26 can be attached to an
end of a spindle shaft member 28, as shown in FIGS. 7 and 8. The
trigger assembly 18 can be retracted to energize the motor 22 to
drive the transmission 24. The chuck assembly 26 can be opened and
closed to accept various tool bits.
[0037] It will be appreciated in light of the disclosure that the
drill or driver 10 is but one example in which the transmission 24
can be used. The transmission 24 can be used in various power
tools, consumer goods and/or any device with rotary power where the
ability to limit and control torque can be a benefit. Examples
include, but are not limited to, saws, yard tools, vacuums,
routers, etc.
[0038] Returning to FIG. 1, a shifting mechanism 30 can be actuated
by the user to change the transmission 24 of the right angle drive
drill 12 between a first output speed and a second output speed. As
shown in FIG. 7, for example, the first output speed can be a low
speed condition. As shown in FIG. 8, for example, the second output
speed can be a high speed condition. In one example, a gear ratio
can be established between the low speed condition and the high
speed condition that is about four to one.
[0039] With reference to FIG. 2, the present teachings can also
include a radially expanding clutch assembly 50 that can have a
shaft member 52. The shaft member 52 can receive an input torque
and a gear member 54 can provide an output torque. The radially
expanding clutch assembly 50 can also include a clutch spring 56, a
clutch washer 58 and/or a retaining ring 60, which can act to
contain rolling members 62 within the radially expanding clutch
assembly 50. In various aspects of the present teachings, the
radially expanding clutch assembly 50 can be implemented with the
transmission 24.
[0040] In one example and with reference to FIG. 3, the shaft
member 52 can include four longitudinal grooves 64 that are formed
within the shaft member 52. The four longitudinal grooves 64 can
interrupt an outer cylindrical surface 66 of the shaft member 52
and thus can form radial portions 68 between the four longitudinal
grooves 64. These radial portions 68 can continue an outer surface
contour of the outer cylindrical surface 66 of the shaft member
52.
[0041] The rolling members 62, in this example shown as pins 70,
can reside within the longitudinal grooves 64 of the shaft member
52. As such, a curvature 72 of the longitudinal grooves 64 can be
complimentary to a curvature 74 of one or more suitable rolling
members 62 such as the pins 70. In other examples, the curvature 72
can define a substantially flat portion (i.e., little or no
curvature) on which the rolling members 62 can reside such as the
planes 210, as shown in FIGS. 9, 10, and 11. It will be appreciated
in light of the disclosure that the curvature 72 and the curvature
74 can be the same or varied.
[0042] With reference to FIG. 2 and FIG. 3, the gear member 54 can
have a plurality of lobes 76 that can extend from the gear member
54 and can be disposed between the rolling members 62, as shown in
FIG. 4. The gear member 54 can also include a gear portion 78
having gear teeth 80 that can mesh with other components of the
transmission 24. The clutch spring 56 can encircle (wholly or
partially) the lobes 76 of the gear member 54 and the rolling
members 62. In this regard, the clutch spring 56 can hold the
rolling members 62 and the lobes 76 of the gear member 54 around
the shaft member 52. The retaining ring 60 can hold the clutch
washer 58 so as to contain the clutch spring 56 around the gear
member 54.
[0043] In various aspects of the present teachings, the clutch
spring 56, can define a single spring, multiple springs, other
suitable compliant or elastic members and/or suitable combinations
thereof. In one aspect, the clutch spring 56 can include helical
coils that form a helical spring such that each of the helical
coils contacts (or is disposed closely to) a successive helical
coil, as illustrated in FIG. 2, which can provide a closed coil
configuration. As shown in FIGS. 24, 25 and 26, the coils can be
spaced from one another, which can provide an open coil
configuration. It will be appreciated in light of the disclosure
that the clutch spring can implemented in a cylindrical shape, a
conical shape, other suitable shapes and one or more suitable
combinations thereof.
[0044] FIGS. 4, 5 and 6 illustrate an exemplary progression of the
radially expanding clutch assembly 50 changing between a drive
condition in FIG. 4 and a clutch out or a reduced torque condition
in FIG. 6. In the drive condition the radially expanding clutch
assembly 50 is closed and can direct torque from the shaft member
52 to the gear member 54 with relatively little loss in torque. In
the clutch out or reduced torque condition, as illustrated in FIG.
6, the radially expanding clutch assembly 50 is "open" and can
direct torque at a reduced value (relative to the drive condition)
from the shaft member 52 to the gear member 54.
[0045] It will be appreciated in light of the disclosure that in
some instances torque can be directed from the gear member 54 to
the shaft member 52. Moreover, the radially expanding clutch
assembly 50, even in the clutch out or reduced torque condition
(FIG. 6), can direct some torque to the gear member 54 because the
outer cylindrical surface 66 can still impart some torque on the
rolling members 62.
[0046] With reference to FIG. 4, the rolling members 62 can reside
within the longitudinal grooves 64 of the shaft member 52 and, as
such, the radially expanding clutch assembly 50 is in the drive
condition. In the drive condition, torque can have an exemplary
pathway from a surface 82 of the longitudinal grooves 64 via the
rolling members 62 to a surface 84 of the lobes 76 that extend from
the gear member 54. As a value of torque at the shaft member 52
surpasses a torque threshold value, the rolling members 62, as
illustrated in FIG. 5, can move up the surface 82, out of the
longitudinal grooves 64 and onto the outer cylindrical surfaces 66
of the shaft member 52, as shown in FIG. 6.
[0047] In FIG. 6, the rolling members 62 can move out of the
longitudinal grooves 64 and can stretch (i.e., radially expand) the
clutch spring 56 that can encircle (partially or wholly) the
rolling members 62 and the lobes 76. The rolling members 62 can
roll out of the longitudinal grooves 64 of the shaft member 52 and
can be disposed between the clutch spring 56 and the outer
cylindrical surfaces 66 of the shaft member 52. As such, the
radially expanding clutch assembly 50, as shown in FIG. 6, can be
in the clutch out or the reduced torque condition.
[0048] The radially expanding clutch assembly 50 can contain
various amounts of rolling members 62. The rolling members 62 can
be configured as the pins 70, balls, other suitable rolling members
62 and/or one or more combinations thereof. As illustrated in FIGS.
3, 4, 5, 6, 12 and 13, four rolling members 62 can be implemented
with the examples of the radially expanding clutch assembly 50. As
illustrated in FIGS. 9, 10 and 11, two rolling members 62 can be
implemented with further examples of radially expanding clutch
assembly 200.
[0049] With reference to FIG. 7 and FIG. 8, an example of the
transmission 24 for the right angle driver or drill 12 (FIG. 1) can
establish a torque pathway 100 (illustrated with arrows) that can
define a low speed condition of the transmission 24 in accordance
with the present teachings. In this example, the motor 22 can
connect to an output shaft member 102 having a gear portion 104.
The gear portion 104 having gear teeth 106 can connect to a gear
portion 108 having gear teeth 110 that is on an intermediate shaft
member 112. The meshing of the gear portion 104 on the output shaft
member 102 with the gear portion 108 on the intermediate shaft
member 112 can define a first reduction mesh 114.
[0050] The intermediate shaft member 112 can have a gear portion
116 having gear teeth 118 that can mesh with gear teeth 120 of a
gear portion 122 that is on the shaft member 52. The meshing of the
gear portion 108 on the intermediate shaft member 112 with the gear
portion 122 on the shaft member 52 can form a second reduction mesh
124, i.e., two gear reductions. It will be appreciated in light of
the disclosure that the intermediate shaft member 112, in some
examples, can be omitted. In such examples, the gear portion 104
that is on the output shaft member 102 can directly mesh with the
gear portion 122 that is on the shaft member 52 but this would
necessarily omit one of the reduction meshes mentioned above, i.e.,
a single gear reduction.
[0051] Gear teeth 126 of the gear member 54 can mesh with the gear
teeth 132 of a low speed gear portion 134 that is on the spindle
shaft member 28. The gear teeth 120 of the gear portion 122 on the
shaft member 52 can additionally mesh with gear teeth 128 of a high
speed gear portion 130 that is on the spindle shaft member 28. The
gear teeth 120, 128, however, can maintain a partial engagement
with one another because the gear teeth 120, 128 of each of the
respective gear portions 120, 130 do not completely line up, as
illustrated in FIG. 7. In this example, however, the high speed
gear portion 130 in the low speed condition is not engaged to the
spindle shaft member 28 (i.e., the high speed gear portion 130 is
free to rotate around the spindle shaft member 28). The partial
engagement can be shown to reduce the effort of moving the high
speed gear portion 130 relative to the gear portion 122 on the
shaft member 52.
[0052] As shown in FIG. 7 and FIG. 8, the low speed gear portion
134 and the high speed gear portion 130 on the spindle shaft member
28 can move in a longitudinal direction that is generally parallel
to a longitudinal axis 136 of the spindle shaft member 28. The
shaft member 52 can have a longitudinal axis 138 and the output
shaft member 102 can have a longitudinal axis 140. The high speed
gear portion 130 and the low speed gear portion 134 can move
together between the high speed condition illustrated in FIG. 8 and
the low speed condition illustrated in FIG. 7.
[0053] In the low speed condition and with reference to FIG. 7, the
low speed gear portion 134 can be engaged to the spindle shaft
member 28 (i.e., not free to rotate around the spindle shaft member
28). In this arrangement, torque transmitted to the low speed gear
portion 134 from the gear member 54 can drive the spindle shaft
member 28 and ultimately the chuck assembly 26.
[0054] In the high speed condition and with reference to FIG. 8,
the high speed gear portion 130 can be engaged to the spindle shaft
member 28 (i.e., not free to rotate around the spindle shaft member
28). In the high speed condition, torque transmitted from the gear
portion 104 of the output shaft member 102 to the gear portion 122
on the shaft member 52 is also directed to the high speed gear
portion 130 on the spindle shaft member 28 and thus avoids the gear
member 54. The radially expanding clutch assembly 50, in the above
example, can therefore be bypassed in the high speed condition, as
shown in FIG. 8.
[0055] In the low speed condition as shown in FIG. 7, the gear
member 54 of the radially expanding clutch assembly 50 can drive
the low speed gear portion 134 of the spindle shaft member 28 that
is engaged to the spindle shaft member 28. When the torque value is
below the threshold amount, the motor 22 can drive the spindle
shaft member 28 via the low speed gear portion 134 of the spindle
shaft member 28 and the gear member 54 of the radially expanding
clutch assembly 50. In the high speed condition, as shown in FIG.
8, the motor 22 can drive the spindle shaft member 28 via the high
speed gear portion 130 that can be engaged to the spindle shaft
member 28 and the gear portion 122 on the shaft member 52. In this
arrangement, the gear member 54 can provide little to no torque to
the low speed gear portion 130.
[0056] As noted in the above examples, the transmission 24 can be
switched between the high speed condition and the low speed
condition and can provide a four to one gear ratio. In other
aspects, the gear ratios established by the configuration of the
gearing discussed throughout the disclosure can be configured in
various aspects to, for example, produce different gear ratios to
accommodate different requirements for the drill or driver 10. As
needed, the torque threshold value can also be adjusted by varying
the configuration of the surfaces 82, 84 of the longitudinal
grooves 64 and/or the lobes 76, respectively, and/or adjusting the
spring constant of the one or more clutch springs 56. It will be
appreciated in light of the disclosure that while spur and helical
gears are illustrated, various gear teeth configurations (i.e.,
spur, helical, hypoid, bevel, etc.) can be used on various gears in
the transmission 24, as applicable.
[0057] In one example, the low speed gear portion 134 and the high
speed gear portion 130 are separate gears that move relative to the
spindle shaft member 28. The gears can engage and disengage to the
spindle shaft member 28 by engaging with splines formed on the
spindle shaft member 28 that can mesh with splines formed on the
gears. In one longitudinal position along the spindle shaft member
28, the splines can be engaged and, in other longitudinal
positions, the splines can be separated (i.e., axially disposed
from one another) so that the gear can spin freely around the
spindle shaft member 28. It will be appreciated that the splines,
gear teeth, etc. can be formed with various suitable manufacturing
processes, such as hobbing, index milling, grinding, etc. In other
examples, the gears, splines, etc. can be formed with powdered
metal forming techniques.
[0058] In operation, as the motor 22 drives the transmission 24,
the transmission 24 can reduce rotational velocity and increase
torque relative to an initial rotational velocity and initial
torque provided by the motor 22. As long as the value of torque at
the shaft member 52 remains below the torque threshold value, the
radially expanding clutch assembly 50 can remain in the drive
condition. In the drive condition, the shaft member 52 can drive
the gear member 54 with relatively little loss in the value of the
torque across the radially expanding clutch assembly 50.
[0059] With reference to FIGS. 9, 10 and 11, one alternative
example of a radially expanding clutch assembly 200 is shown with a
clutch spring 202 and/or other suitable compliant portions. The
clutch spring 202 can be a unitary member (e.g., a sleeve) that can
encircle (partially or wholly) the lobes 204 of a gear member 206
and/or rolling members 208. Similar to the radially expanding
clutch assembly 50 (FIG. 2) discussed above, as the value of torque
surpasses the torque threshold value, the rolling members 208 can
roll beyond planes 210. The planes 210 can be longitudinal grooves
212 that can be substantially flat, i.e., little or no curvature.
As the rolling members 208 move from the planes 210 to the outer
cylindrical surface 216, the radially expanding clutch assembly 200
moves from a drive condition (FIG. 9) to a clutch out (reduced
torque) condition (FIG. 11), as the shaft member 214 is no longer
able to impart substantial torque to the gear member 206.
[0060] With reference to FIG. 9, the clutch spring 202 is shown in
a generally circular shape 218 that can be indicative of the drive
condition. In the drive condition, the radially expanding clutch
assembly 200 can deliver about the same amount of torque between
the shaft member 214 and the gear member 206.
[0061] With reference to FIG. 11, the clutch spring 202 is shown in
generally an elliptical shape 220, which is indicative of the
clutch out or the reduced torque condition. In the clutch out or
reduced torque condition, torque delivered at the gear member 206
of the radially expanding clutch assembly 200 is reduced relative
to the value of torque at the shaft member 214. As the rolling
members 208 roll beyond the planes 210, the rolling members 208 can
move onto the outer cylindrical surface 216 of the shaft member
214. When the rolling members 208 move onto the outer cylindrical
surface 216, the rolling members 208 can stretch (i.e., radially
expand) the clutch spring 202 so as to form generally the
elliptical shape 220 (FIG. 11).
[0062] The lobes 204 of the gear member 206 can have an arcuate
outer surface 222. A shape of the arcuate outer surface 222 and the
configuration of the clutch spring 202 in the drive condition can
define a space 224 between the clutch spring 202 and the arcuate
outer surface 222 of the lobe 204. With reference to FIG. 11, the
clutch spring 202 in the generally elliptical shape 220 can be
stretched to a degree such that portions of the clutch spring 202
can reduce or eliminate the space 224 in the reduced torque
condition.
[0063] In one example, the clutch spring 202 can fully contact the
arcuate outer surface 222 and in other examples the clutch spring
202 can approach the arcuate outer surface 222. When the clutch
spring 202 expands to take the generally taken the elliptical shape
220 and the radially expanding clutch assembly 200 is in the clutch
out or reduced torque condition, the clutch spring 202 can
additionally form spaces 226 between ends 228 of the lobes 204 and
the clutch spring 202 adjacent to the rolling members 208. The ends
228 of the lobes 204 can be adjacent to surfaces 230 that can abut
the rolling members 208.
[0064] In accordance with various aspects of the present teachings
and with reference to FIG. 12, a radially expanding clutch assembly
300 can be similar to the radially expanding clutch assembly 50, as
shown in FIG. 4. The radially expanding clutch assembly 300 can
have a clutch spring 302 that can encircle (partially or wholly)
rolling members 304 and lobes 306 of a gear member 308. The rolling
members 304 can be disposed in longitudinal grooves 310 formed in a
shaft member 312. In one aspect, the clutch spring 302 can be a
unitary member (e.g., a sleeve) and, as such, can continuously
encircle the rolling members 304 and the lobes 306.
[0065] With reference to FIG. 13, a radially expanding spring
clutch assembly 350 can be similar to the radially expanding clutch
assembly 300, as shown in FIG. 12. The radially expanding spring
clutch assembly 350 can have a clutch spring 352 that can encircle
(partially or wholly) rolling members 354 and lobes 356 of a gear
member 358. The rolling members 354 can be disposed in longitudinal
grooves 360 formed in a shaft member 362. The clutch spring 352 can
be a coil spring or a power spring or also may be referred to as a
spiral coiled spring.
[0066] In one aspect, an outside end 364 of the clutch spring 352
can be revolved around an inside end 366 of the clutch spring 352
so as to tighten or loosen the clutch spring 352. Tightening of the
clutch spring 352 can increase the torque threshold value
associated with the spring clutch assembly 300. As illustrated in
FIG. 13, the outside end 364 can be revolved in a clockwise
direction relative to the inside end 366 to increase a spring force
exerted by the clutch spring 352. The outside end 364 can also be
revolved in a counterclockwise direction relative to the inside end
366 to decrease the spring force exerted by the clutch spring 352
thus decreasing the torque threshold value. Portions of clutch
spring 352 can be spaced at increasing radial distances from the
shaft member 362, e.g., a spiral wound spring. The increasing
radial distance can be along an arrow 368 that can be generally
perpendicular to an outer cylindrical surface 370 of the shaft
member 362.
[0067] With reference to FIGS. 14, 15 and 16, a transmission 400
includes a shaft member 402 on which a first gear assembly 404 and
second gear assembly 406 can move generally about a longitudinal
axis 408 of the shaft member 402. The first gear assembly 404 can
include a first clutch spring 410 that holds a first set 412 of
rolling members 414 between lobes 416 that can extend from a first
output gear 418. A second gear assembly 406 can include a second
clutch spring 420 that can hold a second set 422 of rolling members
424 between lobes 426 that extend from a second output gear
428.
[0068] The first output gear 418 and the second output gear 428 can
move longitudinally along the shaft member 402 to a position that
can cause one or both of the output gears 418, 428 to engage for
rotation with the shaft member 402. More specifically, the shaft
member 402 can include a continuous cylindrical surface portion 430
that can be longitudinally disposed next to a cylindrical outer
surface portion 432 that can be interrupted by longitudinal grooves
434. In one example, the longitudinal grooves 434 can be formed at
equally spaced radial positions along the shaft member 402.
[0069] When the first gear assembly 404 is engaged to the shaft
member 402, the first set 412 of rolling members 414 can be held
within the longitudinal grooves 434 of the shaft member 402. When
torque is imparted on the shaft member 402, a surface 436 of the
longitudinal grooves 434 can transfer torque to a surface 438 of
the lobes 416 of the first output gear via the rolling members 414.
As the value of torque surpasses a torque threshold value at the
shaft member 402, the first set 412 of rolling members 414 can be
urged out of the longitudinal grooves 434 and migrate to the
cylindrical outer surface portion 432 of the shaft member 402. Once
the first set 412 of rolling members 414 advance along the surface
436 of the longitudinal grooves 434 to arrive at the cylindrical
outer surface portion 432 of the shaft member 402. In this regard,
the transmission 400 can move from a drive condition to a reduced
torque or clutch out condition.
[0070] In one example and with reference to FIG. 18, the surfaces
436 of the longitudinal grooves 434 can define a curvature 440 that
can vary along longitudinal positions of the shaft member 402. The
first gear assembly 404 and/or the second gear assembly 406 can
engage the shaft member 402 at specific longitudinal positions of
the shaft member 402. The curvature 440 of the longitudinal grooves
434 at the specific longitudinal positions can correlate with a
known and predetermined torque threshold value. If a different
torque threshold value is required, the first gear assembly 404
and/or the second gear assembly 406 can be moved along the shaft
member 402 so that the rolling members 414, 424, as applicable,
engage the longitudinal grooves 434 in a longitudinal position with
a different curvature of the longitudinal groves 434 thus a
different torque threshold value.
[0071] The shaft member 402 can have at least three regions: a
first region 450, a second region 452 and a third region 454. The
first region 450 can define a continuous cylindrical outer surface
456 that can be at a nominal shaft diameter; nominal being relative
to the diameter of the shaft member 402 in the second region 452.
To that end, the second region 452 can define the continuous
cylindrical surface portion 430. The third region 454 can define
the cylindrical outer surface portion 432 that is interrupted by
the longitudinal grooves 434. In one example, the first region 450
can define a continuous cylindrical outer surface 456 that can
otherwise be interrupted by longitudinal grooves 435 that can be
similar to (or different from) longitudinal grooves 434.
[0072] In one aspect, the continuous cylindrical surface portion
430 that can have a reduced diameter relative to the continuous
cylindrical surface portion 456 in the first region 450. The first
gear assembly 404, for example, can move longitudinally from having
the rolling members 414 contained within the longitudinal grooves
434 (i.e., engaged to the shaft member 402) to a location on the
shaft member 402 where the rolling members 414 contact the
continuous cylindrical surface portion 430 having the reduced
diameter. Because the continuous cylindrical surface portion 430
lacks any longitudinal grooves 434, the first gear assembly is free
to rotate around the shaft member 402.
[0073] The clutch spring 410 and the clutch spring 420 can each be
a single unitary member and can encircle (partially or wholly) both
the first and second set of rolling members 414, 424 on the first
and second gear assembly 404, 406 thus encircling the lobes 416,
426 and rolling members 414, 424 in each of the gear assemblies
404, 406. In further aspects, separate clutch springs, can be used
with the first gear assembly 404 and a second gear assembly 406
respectively. The first clutch spring 410 can have a first spring
constant and the second clutch spring 420 can have a second spring
constant.
[0074] In some examples, the spring constants can be equal and in
other examples, the spring constants can be different. It will be
appreciated in light of the disclosure that the threshold torque
value associated with one or more of the gear assemblies 414, 424
can be adjusted by altering the curvature of the longitudinal
grooves, the angle of the surface of the lobes to which the rolling
members connect, the spring constant of the respective clutch
springs and/or one or more combinations thereof.
[0075] In FIG. 17, a relationship between a value of an angle 442
and the torque threshold value is shown. With respect to the
transmission 400 illustrated in FIGS. 14, 15 and 16, the angle 442
can be defined between the surface 438 of the lobes 416 in the
first gear assembly 404 and the surface 436 of the longitudinal
grooves 434 of the shaft member 402. The relationship between the
value of the angle 442 and the torque threshold value is shown such
that as the angle 442 decreases, the value of the torque threshold
increases. In other examples, the angle 442 can be defined between
the surface 84 of the lobes 76 and the surface 82 of the
longitudinal grooves 64, as shown in FIGS. 3, 4, 5 and 6. In a
further example, the angle 442 can be defined between the plane 210
and the abutting end 230 of the lobes 204, as shown in FIGS. 9, 10
and 11.
[0076] With reference to FIG. 19, an exemplary shaft member 500 is
shown having at least three regions: a first region 502, a second
region 504 and a third region 506. The first region 502 can include
a continuous cylindrical surface portion 508. The second region 504
can include a cylindrical surface portion 510 interrupted by
longitudinal grooves 512. In this example, the longitudinal grooves
512 can define planar portions 514, i.e., no curvature. Ramps 516
or other suitable contoured portions can provide one or more
transitions between the regions 502, 504, 506.
[0077] The third region 506 can include a cylindrical surface
portion 518 interrupted by longitudinal grooves 520 having a
curvature 522. The curvature 522 of the longitudinal grooves 520
can vary along a longitudinal axis 524 so as to have a first
curvature 526 and a second curvature 528 at specific locations
along the shaft member 500.
[0078] With reference to FIG. 20, a cross-section of the shaft
member 500 is shown at a particular longitudinal location. At this
longitudinal location, the longitudinal grooves 512 are configured
to have planar portions 514 that interrupt the cylindrical outer
surface portions 510 of the shaft member 500. With reference to
FIG. 21, another longitudinal location of the shaft member 500 is
shown. In this longitudinal location, the outer cylindrical surface
portion 518 is interrupted by longitudinal grooves 520 having the
curvature 522 that can establish a first curvature configuration
526 that is associated with a predetermined torque threshold
value.
[0079] With reference to FIG. 22, an additional longitudinal
location is shown of the shaft member 500. In this longitudinal
location, the outer cylindrical portion 518 is interrupted by the
longitudinal grooves 520 having the curvature 522 configured with a
second curvature configuration 528 that is associated with another
predetermined torque threshold value. It will be appreciated in
light of the disclosure that the first gear assembly 404 and/or the
second gear assembly 406 can be orientated along the shaft member
500 so that the respective rolling members 414, 416 can reside in
the longitudinal grooves 520 at one or more of the above specific
longitudinal locations.
[0080] With reference to FIG. 23, an alternative exemplary shaft
member 600 can include an outer cylindrical surface portion 602
that is interrupted by the longitudinal grooves 604. The
longitudinal grooves 604 can include a curvature 606. The curvature
606 can be configured in a V-shape. It will be appreciated in light
of the disclosure that changing the configuration of the v-shape
curvature can also adjust the torque threshold value.
[0081] In various aspects of the present teachings and with
reference to FIG. 24, a clutch spring 700 can include helical coils
702 that can provide a helical spring 704 such that each of the
helical coils 702 is spaced apart from each other. Ends 706 (one
end or both ends) of the helical coils 702 can have a reduced
cross-section (e.g., a ground end) so that when, for example, the
clutch spring 700 is compressed axially, the ends 706 of the clutch
spring 700 can provide a relatively more flat end of the clutch
spring 700.
[0082] The clutch spring 700 can define a substantially flat
cross-section that can be maintained throughout the entire clutch
spring 700 or portions thereof. The substantially flat
cross-section can define a generally rectangular cross-section
having two parallel sides that are substantially longer than the
adjacent pair of parallel sides so as establish the substantially
flat cross-section. In addition, intersections of the parallel
sides (i.e., corners) can be rounded or chamfered.
[0083] With reference to FIG. 25, a clutch spring 730 can include
helical coils 732 that can provide a helical spring 734 such that
each of the helical coils 732 is spaced apart from each other. Ends
736 (one end or both ends) of the helical coils 732 can be spaced
from the immediately adjacent helical coil so as to establish an
open condition, i.e., the ends 736 of the helical coils 732 do not
touch other portions of the clutch spring 730. Like the clutch
spring 700, the clutch spring 730 can define a substantially flat
cross-section that can be maintained throughout the entire clutch
spring 730 or portions thereof.
[0084] With reference to FIG. 26, a clutch spring 750 can include
helical coils 752 that can provide a helical spring 754 such that
each of the helical coils 752 is spaced apart from each other. The
ends 756 (one end or both ends) of the helical coils 752 are
configured to contact the immediately adjacent helical coil so as
to establish a closed end condition, i.e., the ends 756 of the
helical coils 752 do touch (or are positioned relatively close to)
other portions of the clutch spring 750. Like the clutch spring
700, the clutch spring 750 can define a substantially flat
cross-section that can be maintained throughout the entire clutch
spring 750 or portions thereof. It will be appreciated in light of
the disclosure that one or more of clutch springs 700, 730, 750 can
implemented similar to clutch spring 56, 202, 302, 352, 410, 420
(FIGS. 2, 9, 12, 13 and 14). It will also be appreciated in light
of the disclosure that other suitable cross-sections of the clutch
spring can be used, such as, but not limited to, square and
circular cross-sections. Furthermore, the radially expanding clutch
spring can be implemented in a cylindrical shape, a conical shape,
other suitable shapes and one or more suitable combinations
thereof.
[0085] While specific aspects have been described in the
specification and illustrated in the drawings, it will be
understood by those skilled in the art that various changes can be
made and equivalence can be substituted for elements and components
thereof without departing from the scope of the present teachings,
as defined in the claims. Furthermore, the mixing and matching of
features, elements, components and/or functions between various
aspects of the present teachings are expressly contemplated herein
so that one skilled in the art will appreciate from the present
teachings that features, elements, components and/or functions of
one aspect of the present teachings can be incorporated into
another aspect, as appropriate, unless described otherwise above.
Moreover, many modifications may be made to adapt a particular
situation, configuration or material to the present teachings
without departing from the essential scope thereof. Therefore, it
is intended that the present teachings not be limited to the
particular aspects illustrated by the drawings and described in the
specification as the best mode presently contemplated for carrying
out the present teachings, but that the scope of the present
teachings include many aspects and examples following within the
foregoing description and the appended claims.
* * * * *