U.S. patent application number 13/528978 was filed with the patent office on 2012-12-20 for power tool with torque clutch.
Invention is credited to Rodney Milbourne, Christine Potter, Gerald Rescigno, Qiang Zhang.
Application Number | 20120318547 13/528978 |
Document ID | / |
Family ID | 35056265 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120318547 |
Kind Code |
A1 |
Milbourne; Rodney ; et
al. |
December 20, 2012 |
POWER TOOL WITH TORQUE CLUTCH
Abstract
A power tool with a multi-speed transmission and a switch
mechanism for shifting the transmission between a plurality of
different speed ratios. The switch mechanism includes a single
switch member that is slidably mounted on the housing. The power
tool further comprises a clutch having a clutch profile that is
coupled to a ring gear of the transmission. In some examples, the
power tool further comprises a clutch that is configured to
interact with a first stage of the transmission.
Inventors: |
Milbourne; Rodney;
(Abingdon, MD) ; Potter; Christine; (Phoenix,
MD) ; Rescigno; Gerald; (Marriotsville, MD) ;
Zhang; Qiang; (Lutherville, MD) |
Family ID: |
35056265 |
Appl. No.: |
13/528978 |
Filed: |
June 21, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12966678 |
Dec 13, 2010 |
8220561 |
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13528978 |
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12362825 |
Jan 30, 2009 |
7900714 |
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12966678 |
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|
11237112 |
Sep 28, 2005 |
7537064 |
|
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12362825 |
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10792659 |
Mar 3, 2004 |
7101300 |
|
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11237112 |
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10384809 |
Mar 10, 2003 |
6984188 |
|
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10792659 |
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09964078 |
Sep 26, 2001 |
6676557 |
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10384809 |
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60263379 |
Jan 23, 2001 |
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Current U.S.
Class: |
173/47 |
Current CPC
Class: |
B25F 5/006 20130101;
F16H 2200/0039 20130101; B25F 5/02 20130101; F16H 2200/201
20130101; B23B 2260/11 20130101; B25B 21/00 20130101; F16H 63/18
20130101; B23B 45/008 20130101; B23Q 5/142 20130101; F16H 2200/2035
20130101; F16H 2200/0043 20130101; F16H 3/64 20130101; F16H
2200/0034 20130101; B25B 23/14 20130101; B25F 5/001 20130101 |
Class at
Publication: |
173/47 |
International
Class: |
B25F 5/00 20060101
B25F005/00 |
Claims
1. A power tool comprising: a housing; a motor received in the
housing and having an output shaft; an output spindle; a
transmission having a plurality of planetary transmission stages
comprising a first planetary transmission stage, at least one
intermediate stage and an output stage, the first planetary stage
receiving rotary power directly from the output shaft of the motor,
the first planetary stage having a ring gear and outputting rotary
power to the at least one intermediate stage, the at least one
intermediate stage outputting power to the output stage, the output
stage having an output member that is coupled to output spindle,
the transmission being operable in at least three different speed
ratios; a clutch assembly that comprises a clutch profile and an
engagement assembly, the clutch profile being coupled to the ring
gear, the engagement assembly including a follower and an
adjustment collar, the adjustment collar being movable to change a
magnitude of a biasing force exerted by the follower member onto
the clutch profile, the follower assembly cooperating with the
clutch profile to permit continuous rotation of the ring gear of
the first planetary transmission stage relative to the housing when
the magnitude of the intermediate output torque exceeds a selected
maximum torque to thereby limit rotary power that is output through
the output member to a selected maximum tool torque, the follower
assembly also cooperating with the clutch profile to inhibit
rotation of the first ring gear relative to the housing when the
magnitude of the intermediate torque does not exceed the selected
clutch torque; and a switch mechanism for shifting the transmission
between the at least three different speed ratios, the switch
mechanism comprising a single switch member that is slidably
mounted on the housing for movement between a first switch
position, a second switch position and a third switch position,
wherein the transmission operates in a first speed ratio when the
switch member is in the first position, the transmission operates
in a second speed ratio when the switch member is in the second
position and the transmission operates in a third speed ratio when
the switch member is in the third position.
2. The power tool of claim 1, wherein the switch member is
rotatably mounted on the housing.
3. The power tool of claim 2, wherein the switch member is
rotatably about an axis that is coincident with a rotational axis
of the output spindle and the output shaft.
4. The power tool of claim 1, wherein the clutch profile faces the
at least one intermediate stage.
5. The power tool of claim 1, wherein the ring gear has opposite
axial ends and wherein the clutch profile is located on the ring
gear between the opposite axial ends of the ring gear.
6. The power tool of claim 5, wherein the clutch profile is defined
by an annular member that is received onto an annular flange formed
about the ring gear.
7. The power tool of claim 6, wherein a cushioning member is
disposed between the annular member and the annular flange.
8. The power tool of claim 1, wherein the switch mechanism further
comprises a cam and a pair of followers, the cam being mounted to
the single switch member for rotation therewith, the cam defining a
first set of cam tracks and a second set of cam tracks, each of the
followers being coupled to a corresponding movable element in the
transmission, the first and second cam tracks being configured to
coordinate movement of the followers in a predetermined manner as
the single switch member is moved between the first, second and
third switch positions.
9. A power tool comprising: a housing; a motor received in the
housing and having an output shaft; an output spindle; a
transmission having a plurality of planetary transmission stages
comprising a first planetary transmission stage and an output
stage, the first planetary stage receiving rotary power directly
from the output shaft of the motor, the output stage having an
output member that is coupled to output spindle, the transmission
being operable in a plurality of different speed ratios; a clutch
assembly that comprises a clutch profile and an engagement
assembly, the clutch profile being coupled to the ring gear, the
engagement assembly including a follower and an adjustment collar,
the adjustment collar being movable to change a magnitude of a
biasing force exerted by the follower member onto the clutch
profile, the follower assembly cooperating with the clutch profile
to permit continuous rotation of the ring gear of the first
planetary transmission stage relative to the housing when the
magnitude of the intermediate output torque exceeds a selected
maximum torque to thereby limit rotary power that is output through
the output member to a selected maximum tool torque, the follower
assembly also cooperating with the clutch profile to inhibit
rotation of the first ring gear relative to the housing when the
magnitude of the intermediate torque does not exceed the selected
clutch torque; and a switch mechanism for shifting the transmission
between the different speed ratios, the switch mechanism comprising
a single switch member that is slidably mounted on the housing.
10. The power tool of claim 9, wherein the switch member is
rotatably mounted on the housing.
11. The power tool of claim 10, wherein the switch member is
rotatably about an axis that is coincident with a rotational axis
of the output spindle and the output shaft.
12. The power tool of claim 9, wherein the clutch profile faces
toward the output stage.
13. The power tool of claim 9, wherein the ring gear has opposite
axial ends and wherein the clutch profile is located on the ring
gear between the opposite axial ends of the ring gear.
14. The power tool of claim 13, wherein the clutch profile is
defined by an annular member that is received onto an annular
flange formed about the ring gear.
15. The power tool of claim 14, wherein a cushioning member is
disposed between the annular member and the annular flange.
16. The power tool of claim 9, wherein the switch mechanism further
comprises a cam and a follower, the cam being mounted to the single
switch member for rotation therewith, the cam defining a set of cam
tracks, the follower being coupled to a movable element in the
transmission, the set of cam tracks being configured to coordinate
movement of the follower in a predetermined manner as the single
switch member is moved on the housing.
17. The power tool of claim 9, wherein the transmission is operable
in at least three different speed ratios.
18. A power tool comprising: a housing defining a motor cavity and
a handle, the motor cavity defining a longitudinal axis of the
power tool, the housing having first and second axial ends, the
handle being disposed between the first and second ends such that
the handle is axially offset from the first end and axially offset
from the second end; a motor received in the motor cavity and
having an output shaft; a planetary transmission having a plurality
of stages including a first stage, at least one intermediate stage
and an output stage, the first planetary stage receiving rotary
power directly from the output shaft of the motor, the first
planetary stage outputting rotary power to the at least one
intermediate stage, the at least one intermediate stage outputting
power to the output stage, the output stage having an output member
that is coupled to output spindle, the transmission being operable
in at least three different speed ratios, wherein one of the
plurality of stages has a ring gear; a clutch assembly that
comprises a clutch profile and an engagement assembly, the clutch
profile being coupled to the ring gear, the engagement assembly
including a follower and an adjustment collar, the adjustment
collar being movable to change a magnitude of a biasing force
exerted by the follower member onto the clutch profile; and a
switch mechanism for shifting the transmission between the at least
three different speed ratios, the switch mechanism comprising a
single switch member that is slidably mounted on the housing for
movement between a first switch position, a second switch position
and a third switch position, wherein the transmission operates in a
first speed ratio when the switch member is in the first position,
the transmission operates in a second speed ratio when the switch
member is in the second position and the transmission operates in a
third speed ratio when the switch member is in the third
position.
19. The power tool of claim 18, wherein the ring gear is in the
first planetary stage.
20. The power tool of claim 18, wherein the switch mechanism
further comprises a cam and a follower, the cam being mounted to
the single switch member for rotation therewith, the cam defining a
set of cam tracks, the follower being coupled to a movable element
in the transmission, the set of cam tracks being configured to
coordinate movement of the follower in a predetermined manner as
the single switch member is moved on the housing.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Ser. No.
12/966,678 filed Dec. 13, 2010, which is a continuation of U.S.
application Ser. No. 12/362,825 filed Jan. 30, 2009 (now U.S. Pat.
No. 7,900,714 issued Mar. 8, 2011), which is a continuation of U.S.
application Ser. No. 11/237,112 filed Sep. 28, 2005 (now U.S. Pat.
No. 7,537,064 issued May 26, 2009), which is a continuation of U.S.
application Ser. No. 10/792,659 filed Mar. 3, 2004 (now U.S. Pat.
No. 7,101,300 issued Sep. 5, 2006), which is a continuation-in-part
of U.S. application Ser. No. 10/384,809 filed Mar. 10, 2003 (now
U.S. Pat. No. 6,984,188 issued Jan. 10, 2006), which is a
divisional of U.S. application Ser. No. 09/964,078 filed Sep. 26,
2001, entitled First Stage Clutch (now U.S. Pat. No. 6,676,557
issued Jan. 13, 2004), which claims the benefit of U.S. Provisional
Application No. 60/263,379 filed Jan. 23, 2001. The entire
disclosure of each of the above applications is incorporated herein
by reference.
FIELD
[0002] The present disclosure relates generally to power tools such
as rotatable drills, power screwdrivers, and rotatable cutting
devices. More particularly, the present disclosure relates to a
clutch for a multi-speed transmission for a power tool.
BACKGROUND
[0003] This section provides background information related to the
present disclosure which is not necessarily prior art.
[0004] Modernly, manufacturers of power tools have introduced power
tools that have variable speed motors in an attempt to permit the
users of these tools with sufficient control over the output speed
of the tool so as to permit them to perform diverse operations
without resort to additional, specialized tools. Many of the tools
that are commercially available include a three-stage, two-speed
transmission that permits even greater control over speeds of these
tools.
[0005] Typically available transmission arrangements have lacked a
transmission arrangement that could produce a wide range of output
speeds and torques that would permit the tool to perform diverse
operations such as drilling holes with a large diameter hole saw,
installing drywall screws or large diameter lag screws, and
performing high-speed drilling operations. The single or dual speed
transmissions that were generally employed in these tools typically
did not have sufficient speed reducing capacity to permit these
transmissions to be diversely employed as configuring these tools
for high torque operations tended to impair their high speed
performance. Furthermore, the rechargeable batteries that were
employed in many of the early cordless rotary power tools were not
well suited for use in low-speed, high torque operations due to the
amount of energy that is consumed and the rate with which the
energy is consumed by the power tool during such operations.
Consequently, consumers were often forced to purchase two different
rotary power tools, a medium-duty tool for "standard" applications
such as drilling and fastening, and a heavy-duty tool having a
low-speed, high torque output for more demanding tasks.
[0006] With the advent of the modern high capacity, high voltage
battery, it is now possible to meet the energy demands of a power
tool that is used in low-speed, high torque operations. There
remains, however, a need in the art for a power tool transmission
having a relatively large range in its speed reducing capacity.
[0007] Typical clutch arrangements permit the user of the tool to
limit the torque that is output by the last stage of the tool's
transmission. These clutch arrangements commonly employ a spring
that biases two portions of the clutch into engagement. When the
torque that is output by the transmission exceeds the predetermined
clutch setting, the biasing force exerted by the spring is not
sufficient to maintain the portion of the clutch in an engaged
condition and as such, one of the portions of the clutch is able to
rotate relative to the other portion of the clutch. The relative
movement of these two portions effectively inhibits the
transmission of torque to the output shaft of the tool.
[0008] The use of such clutch arrangements with a transmission
having a relatively large speed reducing range is often times
impractical for the simple reason that the biasing force that is
exerted by the spring does not have sufficient range to permit the
clutch portions to be properly engaged and disengaged over the
entire speed reducing range. Accordingly, it is relatively common
to supply several different sized springs with a clutch
arrangement, necessitating that the user select and install an
appropriately sized spring for a given task. While this approach
has been effective, it is nonetheless time consuming and
inconvenient.
SUMMARY
[0009] This section provides a general summary of the disclosure,
and is not a comprehensive disclosure of its full scope or all of
its features.
[0010] In one form, the present disclosure provides a portable
power tool that includes a motor, a transmission, an output member
and a clutch assembly. The motor has an output shaft. The
transmission has a plurality of planetary transmission stages that
include a first planetary transmission stage and a second planetary
transmission stage. Each of the plurality of planetary transmission
stages includes a sun gear, a planet carrier, a plurality of planet
carriers journally supported by the planet carrier and meshingly
engaged to the sun gear, and a ring gear having internal teeth that
are engaged by the plurality of planet gears. The sun gear of the
first planetary transmission stage is directly driven by the output
shaft of the motor. The ring gear of the first planetary
transmission stage is not shared by another of the plurality of
planetary transmission stages. The first planetary transmission
stage receives an input torque from the motor and produces an
intermediate output torque in response thereto that is transmitted
to the second planetary transmission stage. The output member is
drivingly coupled to the transmission on a side of the transmission
opposite the motor. The clutch assembly has a clutch profile and an
engagement assembly. The clutch profile is coupled to a side of the
ring gear of the first planetary transmission stage that is
opposite the motor. The engagement assembly is disposed between the
ring gear of the first planetary transmission stage and the output
member. The engagement assembly including a follower, a follower
spring and an adjustment collar. The follower spring applies a
biasing force that is transmitted to the follower member to bias
the follower member into engagement with the clutch profile. The
adjustment collar is movable to change a magnitude of the biasing
force. The follower assembly cooperates with the clutch profile to
inhibit rotation of the ring gear of the first planetary
transmission stage only when the magnitude of the intermediate
output torque is less than a selected maximum torque.
[0011] In still another form, the present teachings provide a power
tool that includes a housing, a motor, a transmission, an output
member and a clutch assembly. The motor is received in the housing
and has an output shaft. The transmission has a plurality of
planetary transmission stages with a first planetary transmission
stage and a second planetary transmission stage. Each of the
plurality of planetary transmission stages has a sun gear, a
plurality of planet gears meshingly engaged to the sun gear, and a
ring gear with internal teeth that are engaged by the plurality of
planet gears. The sun gear of the first planetary transmission
stage is directly driven by the output shaft of the motor. The ring
gear of the first planetary transmission stage is not shared by
another of the plurality of planetary transmission stages. The
first planetary transmission stage receives an input torque from
the motor and produces an intermediate output torque in response
thereto that is transmitted to the second planetary transmission
stage. The output member is drivingly coupled to the transmission
on a side of the transmission opposite the motor. The clutch
assembly includes a clutch profile and an engagement assembly. The
clutch profile is coupled to a side of the ring gear of the first
planetary transmission stage that is opposite the motor. The
engagement assembly is disposed axially between the ring gear of
the first planetary transmission stage and a distal end of the
output member. The engagement assembly includes a follower and an
adjustment collar that is movable to change a magnitude of a
biasing force exerted by the follower member onto the clutch
profile. The follower assembly cooperates with the clutch profile
to permit continuous rotation of the ring gear of the first
planetary transmission stage relative to the housing when the
magnitude of the intermediate output torque exceeds a selected
maximum torque to thereby limit rotary power that is output through
the output member to a selected maximum tool torque. The follower
assembly also cooperates with the clutch profile to inhibit
rotation of the first ring gear relative to the housing when the
magnitude of the intermediate torque does not exceed the selected
clutch torque.
[0012] In a further form, the present teachings provide a power
tool that includes a housing, a motor, a transmission, an output
member and a clutch assembly. The motor is received in the housing
and includes an output shaft. The transmission has a plurality of
planetary transmission stages including a first planetary
transmission stage and a second planetary transmission stage. The
first planetary transmission stage is directly driven by the output
shaft of the motor and includes a first ring gear that is not
shared with any other of the plurality of transmission stages. The
second planetary transmission stage has an axially movable member
that is movable between a first position and a second position to
permit the second planetary transmission to be selectively operated
in two different speed reduction ratios for transmitting torque.
The output member is driven by the transmission. The clutch
assembly has a clutch profile, which is coupled to the first ring
gear, and a follower assembly with a follower that is disposed
axially between the first ring gear and an output component of the
transmission. The follower is configured to engage and cooperate
with the clutch profile to permit continuous rotation of the first
ring gear relative to the housing when a magnitude of an
intermediate torque output from the first planetary transmission
stage exceeds a selected clutch torque and to inhibit rotation of
the first ring gear relative to the housing when the magnitude of
the intermediate torque does not exceed the selected clutch
torque.
[0013] In another form, the present teachings provide a power tool
that includes a housing, a motor, a planetary transmission, a
clutch assembly and a switch mechanism. The housing defines a motor
cavity and a handle. The motor cavity defines a longitudinal axis
of the power tool. The housing has first and second axial ends. The
handle is disposed between the first and second ends such that the
handle is axially offset from the first end and axially offset from
the second end. The motor is received in the motor cavity and has
an output shaft. The planetary transmission has a plurality of
stages including a first stage, at least one intermediate stage and
an output stage. The first planetary stage receives rotary power
directly from the output shaft of the motor. The first planetary
stage outputs rotary power to the at least one intermediate stage.
The at least one intermediate stage outputs power to the output
stage. The output stage has an output member that is coupled to
output spindle. The transmission is operable in at least three
different speed ratios. One of the plurality of stages has a ring
gear. The clutch assembly includes a clutch profile and an
engagement assembly. The clutch profile is coupled to the ring
gear. The engagement assembly includes a follower and an adjustment
collar. The adjustment collar is movable to change a magnitude of a
biasing force exerted by the follower member onto the clutch
profile. The switch mechanism is configured for shifting the
transmission between the at least three different speed ratios. The
switch mechanism includes a single switch member that is slidably
mounted on the housing for movement between a first switch
position, a second switch position and a third switch position. The
transmission operates in a first speed ratio when the switch member
is in the first position, a second speed ratio when the switch
member is in the second position and a third speed ratio when the
switch member is in the third position.
[0014] In still another form, the present teachings provide a power
tool that includes a housing, a motor, an output spindle, a
transmission, a clutch assembly and a switch mechanism. The motor
is received in the housing and has an output shaft. The
transmission has a plurality of planetary transmission stages
including a first planetary transmission stage and an output stage.
The first planetary stage receives rotary power directly from the
output shaft of the motor, while the output stage has an output
member that is coupled to output spindle. The transmission is
operable in a plurality of different speed ratios. The clutch
assembly that includes a clutch profile and an engagement assembly.
The clutch profile is coupled to the ring gear. The engagement
assembly includes a follower and an adjustment collar. The
adjustment collar is movable to change a magnitude of a biasing
force exerted by the follower member onto the clutch profile. The
follower assembly cooperates with the clutch profile to permit
continuous rotation of the ring gear of the first planetary
transmission stage relative to the housing when the magnitude of
the intermediate output torque exceeds a selected maximum torque to
thereby limit rotary power that is output through the output member
to a selected maximum tool torque. The follower assembly also
cooperates with the clutch profile to inhibit rotation of the first
ring gear relative to the housing when the magnitude of the
intermediate torque does not exceed the selected clutch torque. The
switch mechanism is configured for shifting the transmission
between the different speed ratios. The switch mechanism has a
single switch member that is slidably mounted on the housing.
[0015] In yet another form, the present teachings provide a power
tool that includes a housing, a motor, an output spindle, a
transmission, a clutch assembly and a switch mechanism. The motor
is received in the housing and has an output shaft. The
transmission has a plurality of planetary transmission stages
including a first planetary transmission stage, at least one
intermediate stage and an output stage. The first planetary stage
receives rotary power directly from the output shaft of the motor.
The first planetary stage has a ring gear and outputs rotary power
to the at least one intermediate stage. The at least one
intermediate stage outputs power to the output stage. The output
stage has an output member that is coupled to output spindle. The
transmission is operable in at least three different speed ratios.
The clutch assembly includes a clutch profile and an engagement
assembly. The clutch profile is coupled to the ring gear. The
engagement assembly includes a follower and an adjustment collar.
The adjustment collar is movable to change a magnitude of a biasing
force exerted by the follower member onto the clutch profile. The
follower assembly cooperates with the clutch profile to permit
continuous rotation of the ring gear of the first planetary
transmission stage relative to the housing when the magnitude of
the intermediate output torque exceeds a selected maximum torque to
thereby limit rotary power that is output through the output member
to a selected maximum tool torque. The follower assembly also
cooperates with the clutch profile to inhibit rotation of the first
ring gear relative to the housing when the magnitude of the
intermediate torque does not exceed the selected clutch torque. The
switch mechanism is configured for shifting the transmission
between the at least three different speed ratios and includes a
single switch member that is slidably mounted on the housing for
movement between a first switch position, a second switch position
and a third switch position. The transmission operates in a first
speed ratio when the switch member is in the first position, a
second speed ratio when the switch member is in the second
position, and a third speed ratio when the switch member is in the
third position.
[0016] Further areas of applicability will become apparent from the
description provided herein. The description and specific examples
in this summary are intended for purposes of illustration only and
are not intended to limit the scope of the present disclosure.
DRAWINGS
[0017] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and are not intended to limit the scope of the present
disclosure.
[0018] Additional advantages and features of the present disclosure
will become apparent from the subsequent description and the
appended claims, taken in conjunction with the accompanying
drawings, wherein:
[0019] FIG. 1 is a side view of a power tool constructed in
accordance with the teaching of the present disclosure;
[0020] FIG. 2 is an exploded perspective view of a portion of the
power tool of FIG. 1;
[0021] FIG. 3 is a perspective view of a portion of the housing of
the power tool of FIG. 1 illustrating the rear of the end cap
assembly;
[0022] FIG. 4 is a front view of the end cap assembly;
[0023] FIG. 5 is a section view taken along the line 5-5 of FIG.
4;
[0024] FIG. 6 is a rear view of a portion of the power tool of FIG.
1 with the end cap assembly removed;
[0025] FIG. 7 is a side view of a portion of the power tool of FIG.
1 with the end cap assembly removed;
[0026] FIG. 8 is a view similar to that of FIG. 4, but illustrating
the end cap shell prior to the overmolding operation;
[0027] FIG. 9 is a view similar to that of FIG. 5, but illustrating
the end cap shell prior to the overmolding operation;
[0028] FIG. 10 is a view similar to that of FIG. 4, but
illustrating an alternate construction of the overmold member;
[0029] FIG. 11 is a partial sectional view of a portion of a power
tool that employs an end cap assembly having an overmold member
constructed in the manner illustrated in FIG. 10;
[0030] FIG. 12 is an exploded perspective view of a portion of the
power tool of FIG. 1, illustrating the transmission assembly in
greater detail;
[0031] FIG. 13 is an exploded perspective view of a portion of the
power tool of FIG. 1, illustrating the reduction gearset assembly,
the transmission sleeve, a portion of the housing and a portion of
the clutch mechanism in greater detail;
[0032] FIG. 13a is a sectional view taken along a longitudinal axis
of the second ring gear;
[0033] FIG. 13b is a sectional view taken along a longitudinal axis
of the third ring gear;
[0034] FIG. 14 is a side view of the transmission sleeve;
[0035] FIG. 15 is a rear view of the transmission sleeve;
[0036] FIG. 16 is a sectional view taken along the line 16-16 of
FIG. 15;
[0037] FIG. 17 is a sectional view taken along the line 17-17 of
FIG. 15;
[0038] FIG. 18 is an exploded view of the reduction gearset
assembly;
[0039] FIG. 19 is a sectional view taken along a longitudinal axis
of the power tool of FIG. 1 illustrating a portion of the reduction
gearset assembly in greater detail;
[0040] FIG. 20 is a front view of a portion of the first reduction
carrier;
[0041] FIG. 21 is a sectional view taken along a longitudinal axis
of the power tool of FIG. 1 illustrating a portion of the reduction
gearset assembly in greater detail;
[0042] FIG. 22 is a rear view of a portion of the third reduction
carrier;
[0043] FIG. 23 is an sectional view taken along the longitudinal
axis of the power tool of FIG. 1 and illustrating the transmission
assembly as positioned in the first speed ratio;
[0044] FIG. 24 is a sectional view similar to that of FIG. 23 but
illustrating the transmission assembly as positioned in the second
speed ratio;
[0045] FIG. 25 is a sectional view similar to that of FIG. 23 but
illustrating the transmission assembly as positioned in the third
speed ratio;
[0046] FIG. 26 is a top view of a portion of the power tool of FIG.
1 illustrating the speed selector mechanism in greater detail;
[0047] FIG. 27a is a side view of the rotary selector cam;
[0048] FIG. 27b is a top view of the rotary selector cam;
[0049] FIG. 27c is a sectional view taken through along the central
axis of the speed selector mechanism;
[0050] FIG. 28 is a rear view of the output spindle assembly;
[0051] FIG. 29 is an exploded perspective view of the clutch
mechanism;
[0052] FIG. 29a is a perspective view of a portion of the clutch
mechanism illustrating another configuration of the clutch
member;
[0053] FIG. 29b is an exploded perspective view illustrating a
multi-piece construction for the first ring gear and clutch
member;
[0054] FIG. 30 is a schematic illustration of the adjustment
structure in an "unwrapped" state;
[0055] FIG. 31 is a schematic illustration similar to that of FIG.
30 but showing an alternate construction of the adjustment profile;
and
[0056] FIG. 32 is a schematic illustration similar to that of FIG.
30 but showing a portion of another alternate construction of the
adjustment profile;
[0057] FIGS. 33 through 35 are sectional views similar to FIGS. 23
through 25, respectively, taken along the longitudinal axis of a
second transmission constructed in accordance with the teachings of
the present disclosure;
[0058] FIGS. 36 through 38 are sectional views similar to FIGS. 23
through 25, respectively, taken along the longitudinal axis of a
third transmission constructed in accordance with the teachings of
the present disclosure;
[0059] FIGS. 39 through 41 are sectional views similar to FIGS. 23
through 25, respectively, taken along the longitudinal axis of a
fourth transmission constructed in accordance with the teachings of
the present disclosure;
[0060] FIGS. 42 through 44 are sectional views similar to FIGS. 23
through 25, respectively, taken along the longitudinal axis of a
fifth transmission constructed in accordance with the teachings of
the present disclosure;
[0061] FIGS. 45 through 47 are sectional views similar to FIGS. 23
through 25, respectively, taken along the longitudinal axis of a
sixth transmission constructed in accordance with the teachings of
the present disclosure;
[0062] FIGS. 48 through 50 are sectional views similar to FIGS. 23
through 25, respectively, taken along the longitudinal axis of a
seventh transmission constructed in accordance with the teachings
of the present disclosure;
[0063] FIGS. 51 through 53 are sectional views similar to FIGS. 23
through 25, respectively, taken along the longitudinal axis of an
eighth transmission constructed in accordance with the teachings of
the present disclosure; and
[0064] FIGS. 54 through 56 are sectional views similar to FIGS. 23
through 25, respectively, taken along the longitudinal axis of a
ninth transmission constructed in accordance with the teachings of
the present disclosure.
[0065] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION
[0066] Example embodiments will now be described more fully with
reference to the accompanying drawings.
[0067] With reference to FIGS. 1 and 2 of the drawings, a power
tool constructed in accordance with the teachings of the present
disclosure is generally indicated by reference numeral 10. As those
skilled in the art will appreciate, the preferred embodiment of the
present disclosure may be either a cord or cordless (battery
operated) device, such as a portable screwdriver or drill (e.g.,
drill, hammer drill). In the particular embodiment illustrated,
power tool 10 may be a cordless drill having a housing 12, a motor
assembly 14, a multi-speed transmission assembly 16, a clutch
mechanism 18, an output spindle assembly 20, a chuck 22, a trigger
assembly 24 and a battery pack 26. Those skilled in the art will
understand that several of the components of power tool 10, such as
the chuck 22, the trigger assembly 24 and the battery pack 26, can
be conventional in nature and need not be described in significant
detail in this application. Reference may be made to a variety of
publications for a more complete understanding of the operation of
the conventional features of power tool 10. One example of such
publications is commonly assigned U.S. Pat. No. 5,897,454 issued
Apr. 27, 1999, the disclosure of which is hereby incorporated by
reference as if fully set forth herein.
[0068] Housing 12 can include an end cap assembly 30 and a handle
shell assembly 32 that can include a pair of mating handle shells
34. Handle shell assembly 32 can include a handle portion 36 and a
drive train or body portion 38. Trigger assembly 24 and battery
pack 26 can be mechanically coupled to handle portion 36 and can be
electrically coupled to motor assembly 14. Body portion 38 can
include a motor cavity 40 and a transmission cavity 42. Motor
assembly 14 may be housed in motor cavity 40 and can include a
rotatable output shaft 44, which can extend into transmission
cavity 42. A motor pinion 46 having a plurality of gear teeth 46a
may be coupled for rotation with output shaft 44. Trigger assembly
24 and battery pack 26 cooperate to selectively provide electric
power to motor assembly 14 in a manner that is generally well known
in the art so as to control the speed and direction with which
output shaft 44 rotates.
[0069] Transmission assembly 16 may be housed in transmission
cavity 42 and can include a speed selector mechanism 60. Motor
pinion 46 can couple transmission assembly 16 to output shaft 44,
transmitting a relatively high speed, low torque drive input to
transmission assembly 16. Transmission assembly 16 can include a
plurality of reduction elements that can be selectively engaged by
speed selector mechanism 60 to provide a plurality of speed ratios.
Each of the speed ratios can multiply the speed and torque of the
drive input in a predetermined manner, permitting the output speed
and torque of the transmission assembly 16 to be varied in a
desired manner between a relatively low speed, high torque output
and a relatively high speed, low torque output. The transmission
output may be transmitted to the output spindle assembly 20, to
which the chuck 22 may be coupled for rotation, to permit torque to
be transmitted to a tool bit (not shown). The clutch mechanism 18
may be coupled to transmission assembly 16 and may be operable for
limiting the magnitude of the torque associated with the drive
input to a predetermined, selectable torque limit.
Functional Overmold
[0070] With specific reference to FIGS. 2 through 9, end cap
assembly 30 may include an end cap shell 100 and an overmold member
102. In the example provided, the end cap shell 100 may be
injection molded from a plastic material, such as ABS. The end cap
shell 100 defines an end cap cavity 104 that may be sized to
receive the portion of the motor assembly 14 that extends
rearwardly of the handle shell assembly 32. A plurality of first
and second radial tab apertures 108 and 110 and an abutting face
127 can be formed into the forward face 114 of the end cap shell
100 and a plurality of screw bosses 116 can be formed into the
perimeter of the end cap shell 100. Each of the first and second
radial tab apertures 108 and 110 may be sized to receive one of the
first radial tabs 120 and second radial tabs 122, respectively,
that can be formed into the rearward face 124 of the handle shells
34. The first and second radial tab apertures 108 and 110 can
cooperate with the first and second radial tabs 122 to align the
end cap shell 100 to the handle shell assembly 32, as well as to
inhibit relative rotation therebetween. An arcuate portion 128 of
the forward face 114 of the end cap shell 100 may be angled to
match the abutting face 132 of the rearward face 124 of the handle
shells 34. The screw bosses 116 can be employed to fixedly couple
the end cap shell 100 to the motor cover 136 via a plurality of
screws 138. The geometry of the motor cover 136 may be such that it
is constrained to the handle shells 34. As such, fastening of the
end cap shell 100 to the motor cover 136 can fixedly retain the end
cap shell 100 against the rearward face 124 of the handle shell
assembly 32, as well as to close off the rear handle aperture 139
in the handle shell assembly 32.
[0071] A plurality of side apertures 140 can be formed into the
sides of the end cap shell 100 to permit air to flow through the
handle shell assembly 32 and cool the motor assembly 14 in a manner
that is well known in the art. A plurality of rear apertures 144
can be formed into the rear of the end cap shell 100, with each of
the rear apertures 144 including a recessed portion 146, which can
extend partially into the outer surface 148 of the end cap shell
100, and a through-portion 150 that can extend completely through
the end cap shell 100. A pair of retaining tabs 152 can be formed
to extend from the interior surface 154 of the end cap shell 100
inwardly into the end cap cavity 104. A channel 156 may be formed
into the interior surface 154 of the end cap shell 100 and can
intersect each of the rear apertures 144 and the retaining tabs
152.
[0072] The overmold member 102 may be formed from a resilient
material, such as thermoplastic elastomer (e.g., HYTREL.RTM.
manufactured by E.I. du Pont de Nemours and Company) and may be
simultaneously formed and coupled to the end cap shell 100 in an
injection molding operation. In the particular example provided,
the overmold member 102 can include a plurality of bumper members
170, a pair of isolators 172 and a linking member 174. Each of the
bumper members 170 can extend from a point roughly coincident with
the interior surface 154 of the end cap shell 100 to a point
rearwardly of the outer surface 148 of the end cap shell 100 by
about 0.5 mm to about 1.5 mm and preferably about 0.75 mm.
Construction in this manner permits the bumper members 170 to
provide a degree of shock absorption which reduces the likelihood
of damaging the end cap shell 100 in the event that the tool 10 is
dropped. Furthermore, it is sometimes necessary for an operator to
apply a relatively high force to the tool 10, as when employing a
hole saw to drill large diameter holes. In such situations, the
operator is inclined to press onto the rear of the tool 10 to apply
a force that is in-line with the axis of the chuck 22. In such
situations, the bumper members 170 provide the operator with a
relatively soft and comfortable surface which tends to resist
slipping as well as attenuate the vibrations that can be
transmitted to the operator.
[0073] The isolators 172 can be formed about the retaining tabs 152
on the interior surface 154 of the end cap shell 100. In the
example provided, each of the isolators 172 can include an annular
member 180 that extends forwardly of the interior surface 154 of
the end cap shell 100. Construction in this manner permits the end
cap shell 100 to engage the isolators 172 to the outer cylindrical
surface 14a and the rear surface 14b of the motor housing 14c to
fixedly retain the motor 14d within the motor cover 136. This can
prevent the components of the motor assembly 14 from moving along
the longitudinal axis of the tool 10, as well as dampen vibrations
that can be created during the operation of the motor assembly 14.
The linking member 174 may be fixedly coupled to each of the bumper
members 170 and the isolators 172. The linking member 174 can
provide a flow path through which the resilient material flows
during the formation of the bumper members 170 and the isolators
172. The linking member 174 can also interconnect the bumper
members 170 and the isolators 172, thereby rendering their removal
from the end cap shell 100 more difficult.
[0074] Those skilled in the art will appreciate that this aspect of
the present disclosure may be incorporated into various other
positions within the handle assembly 32 for sealing between two or
more components, dampening vibrations or positioning one component
relative to another. One such example is illustrated in FIGS. 10
and 11 where the isolators 172 can be modified to extend around the
perimeter of a portion of the end cap cavity 104 and sealingly
contact the rear surface 14b of the motor 14d. The isolators 172
seal the interface between the end cap shell 100 and the motor
assembly 14, while the bumper members 170 seal the rear apertures
144 in the end cap shell 100. The space 188 defined by the
isolators 172 can be filled with grease or another suitable
lubricant, which lubricates a motor armature bearing 190.
Transmission Assembly
[0075] With reference to FIG. 12, the transmission assembly 16 may
be a three-stage, three-speed transmission that may include a
transmission sleeve 200, a reduction gearset assembly 202 and the
speed selector mechanism 60. With additional reference to FIGS. 13
through 17, the transmission sleeve 200 may include a wall member
210 that can define a transmission bore or hollow cavity 212 into
which the reduction gearset assembly 202 may be disposed. The
transmission sleeve 200 can include a body 214 and a base 216. The
body 214 of the transmission sleeve 200 may be fairly uniform in
diameter and can be generally smaller in diameter than the base
216. The inside diameter of the base 216 may be sized to receive
the cylindrical nose portion 220 of the motor cover 136.
[0076] A plurality of raised lands 226 can be formed into the base
216. The raised lands 226 can define a plurality of first grooves
228 in the outer surface 230 of the base 216 and a plurality of
second grooves 232 in the inner surface 234 of the base 216. The
first grooves 228 can be configured to receive the alignment ribs
238 that can be formed into the inner surface 242 of the handle
shells 34 to align the transmission sleeve 200 to the handle shells
34 and inhibit relative rotation between the transmission sleeve
200 and the housing 12. The first grooves 228 and alignment ribs
238 can be configured in a manner that the transmission sleeve 200
can only be assembled to the handle shells 34 in one orientation
(i.e., the configuration of the first grooves 228 and alignment
ribs 238 prevents the transmission sleeve 200 from being rotated
180.degree. out of position relative to the handle shells 34). The
second grooves 232 will be discussed in greater detail, below.
[0077] The body 214 of the transmission sleeve 200 may include a
cylindrical body portion 246 and a pin housing portion 248. In the
particular embodiment illustrated, the cylindrical body portion 246
can include a selector cam guide 250, a plurality of lubricant
grooves 252 and first and second sets of ring engagement teeth 254
and 256, respectively. The selector cam guide 250 may be generally
rectangular in cross section, extending outwardly from the top of
the outer surface 258 of the body portion 246. The lubricant
grooves 252 can be formed concentrically around the upper half of
the perimeter of the body portion 246. The lubricant grooves 252
have a depth of about 0.01 inch to about 0.030 inch to hold a
lubricant, such as grease, on the upper half of the perimeter of
the body portion 246. The operation of the selector cam guide 250
and the lubricant grooves 252 will be discussed in detail,
below.
[0078] A raised bead 264 can segregate the interior of the body
portion 246 into first and second housing portions 260 and 262,
respectively. The first set of ring engagement teeth 254 can be
formed onto the inner surface 266 of the body portion 246 and can
extend rearwardly from the raised bead 264 toward the base 216. The
second set of ring engagement teeth 256 can be also formed into the
inner surface of the body portion 246 and can extend forwardly from
the raised bead 264. The teeth 268 of the first and second sets of
ring engagement teeth 254 and 256 can be uniformly spaced around
the inner surface 266 of the body portion 246. The configuration of
each tooth 268 in the first and second sets of ring engagement
teeth 254 and 256 can be similar in that each tooth can extend from
the raised bead 264, can have a pair of parallel engagement
surfaces 270 and can terminate at a tip portion 272. The tip
portion 272 of each tooth 268 may be both rounded and tapered to
enhance the ability with which it will mesh with a portion of the
reduction gearset assembly 202 as will be described in detail,
below.
[0079] The pin housing portion 248 can extend downwardly from the
body portion 246 over a portion of the length of the body portion
246. An actuator aperture 274 may be formed into the pin housing
portion 248 and can extend rearwardly through the base 216 of the
transmission sleeve 200. In the particular embodiment illustrated,
the actuator aperture 274 may be stepped, having a first portion
276 with a first diameter at the rear of the transmission sleeve
200 and a second portion 278 with a smaller second diameter at the
front of the transmission sleeve 200. In the example shown, the
first portion 276 of the actuator aperture 274 breaks through the
wall of the first housing portion 260 and forms a groove 280 into
the inner surface 234 of the base 216. The pin housing portion 248
will be discussed in further detail, below.
[0080] A pair of first clip slots 284 and a pair of second clip
slots 286 can be formed into the transmission sleeve 200, extending
along the sides of the transmission sleeve 200 in a manner that may
be parallel the longitudinal axis of the transmission sleeve 200.
The first pair of clip slots 284 may be formed through the sides of
the body portion 246 rearwardly of the raised bead 264 and extends
rearwardly toward the base 216. The depth of the first pair of clip
slots 284 may be such that they do not extend through the portion
of the wall member 210 that defines the base 216. The second pair
of clip slots 286 can be also formed through the sides of the body
portion 246 beginning forwardly of the raised bead 264 and
extending through the front face 288 of the transmission sleeve
200.
[0081] With reference to FIGS. 12, 13, 18 and 23, the reduction
gearset assembly 202 may include a first reduction gear set 302, a
second reduction gear set 304 and a third reduction gear set 306.
The first, second and third reduction gear sets 302, 304 and 306
can be operable in an active mode and in the particular example
provided, the second and third reduction gear sets 304 and 306 may
also be operable in an inactive mode. Operation in the active mode
causes the reduction gear set to perform a speed reduction and
torque multiplication operation, while operation of the reduction
gear set in an inactive mode for causes the reduction gear set to
provide an output having a speed and torque that may be about equal
to the speed and torque of the rotary input provided to that
reduction gear set. In the particular embodiment illustrated, each
of the first, second and third reduction gear sets 302, 304 and 306
can be planetary gear sets. Those skilled in the art will
understand, however, that various other types of reduction gear
sets that can be well known in the art may be substituted for one
or more of the reduction gear sets forming the reduction gearset
assembly 202.
[0082] As shown, the first reduction gear set 302 may include a
first reduction element or ring gear 310, a first set of planet
gears 312 and a first planet or reduction carrier 314. The first
ring gear 310 may be an annular structure, having a plurality of
gear teeth 310a formed along its interior diameter. A clutch face
316 may be formed into the outer perimeter of the front face 318 of
the first ring gear 310 and will be discussed in greater detail,
below. The first ring gear 310 may be disposed within the portion
of the hollow cavity 212 defined by the base 216; the front face
318 of the first ring gear 310 contacts a step 320 formed into the
transmission sleeve 200, thereby limiting the ability of the first
ring gear 310 to move forwardly into the hollow cavity 212.
[0083] The first reduction carrier 314 may be formed in the shape
of a flat cylinder, having plurality of pins 322 that extend from
its rearward face 324. A plurality of gear teeth 314a can be formed
into almost the entire outer perimeter of the first reduction
carrier 314, with a valley 314b being formed between each pair of
adjacent gear teeth 314a. Due to the spacing of the gear teeth
314a, one of the valleys (i.e., valley 314b') is relatively larger
than the remaining valleys 314b due to the omission of a tooth 314a
in the outer perimeter of the first reduction carrier 314. In the
particular embodiment illustrated, the gear teeth 314a of the first
reduction carrier 314 can be configured so as not to be meshingly
engagable with the gear teeth 310a of the first ring gear 310.
[0084] With specific reference to FIGS. 19 and 20, the profile of
the gear teeth 314a is illustrated in greater detail. As shown,
each gear tooth 314a terminates at a gradual radius 326 at the
forward face 328 of the first reduction carrier 314 but terminates
abruptly at the rearward face 324 of the first reduction carrier
314. A radius 330 is also formed on the valleys 314b between the
gear teeth 314a.
[0085] Returning to FIGS. 12, 13, 15, 18 and 23, a first thrust
washer 332 having a first annular portion 334, a second annular
portion 336 and a plurality of retaining tabs 338 may be positioned
rearwardly of the first reduction gear set 302. The retaining tabs
338 engage the second grooves 232 in the base 216 of the
transmission sleeve 200 and as such, relative rotation between the
first thrust washer 332 and the transmission sleeve 200 may be
inhibited. The inside diameter of the base 216 may be sized to
receive the motor cover 136 and as such, the front face 340 of the
motor cover 136 inhibits the axial movement of the first thrust
washer 332. The first annular portion 334 contacts the rear face
342 of the first ring gear 310, providing a wear surface and
controlling the amount by which the first ring gear 310 is able to
move in an axial direction. The second annular portion 336 may be
spaced axially apart from the first annular portion 334, extending
forwardly of the first annular portion 334 to provide a wear
surface for the first set of planet gears 312 that also controls
the amount by which they can move in an axial direction.
[0086] The first set of planet gears 312 may include a plurality of
planet gears 344, each of which being generally cylindrical in
shape, having a plurality of gear teeth 344a formed into its outer
perimeter and a pin aperture 346 formed its their center. Each
planet gear 344 may be rotatably supported on an associated one of
the pins 322 and the first reduction carrier 314 and may be
positioned such that its teeth 344a meshingly engage the teeth 314a
of the first ring gear 310. A raised portion 348 may be formed into
the front and rear face 350 and 352 of each planet gear 344 that
inhibits the teeth 344a from rubbing on the first reduction carrier
314 and the first thrust washer 332 and creating dust or chips that
would impair the performance of the transmission assembly 16 and
reduce its operating life. As the teeth 46a of the motor pinion 46
on the output shaft 44 can be also meshingly engaged with the teeth
344a of the planet gears 344, the motor pinion 46 serves as a sun
gear for the first reduction gear set 302.
[0087] The second reduction gear set 304 may be disposed within the
portion of the hollow cavity 212 defined by the first housing
portion 260 and may include a second sun gear 358, a second
reduction element or ring gear 360, a second set of planet gears
362 and a second planet or reduction carrier 364. The second sun
gear 358 may be fixed for rotation with the first reduction carrier
314. The second sun gear 358 can include a plurality of gear teeth
358a that extend forwardly of the forward face 328 of the first
reduction carrier 314.
[0088] The second ring gear 360 may be an annular structure, having
a plurality of gear teeth 360a formed along its interior diameter.
The gear teeth 360a may be heavily chamfered at the rear face 366
of the second ring gear 360 but terminate abruptly at the front
face 368. More preferably, a heavy radius 369 may be formed onto
the rear face 366 and the sides of each of the gear teeth 360a,
with the heavy radius 369 being employed rather than the heavy
chamfer as the heavy radius 369 on the gear teeth 360a provides for
better engagement between the second ring gear 360 and the first
reduction carrier 314.
[0089] A plurality of sleeve engagement teeth 370 can be formed
into the outer perimeter of the second ring gear 360; the sleeve
engagement teeth 370 extend forwardly toward the front face 368 of
the second ring gear 360 and terminate at a tip portion 372 that
may be rounded and tapers forwardly and inwardly. An annular clip
groove 374 may also formed into the outer perimeter of the second
ring gear 360. In the example illustrated, the clip groove 374 may
be a rectangular slot having a pair of sidewalls 376. The clip
groove 374 will be discussed in greater detail, below.
[0090] The second reduction carrier 364 may be formed in the shape
of a flat cylinder, having plurality of pins 378 that extend from
its rearward face 380. The second set of planet gears 362 may
include a plurality of planet gears 382. Each planet gear 382 may
be generally cylindrical in shape, having a plurality of gear teeth
382a formed into its outer perimeter and a pin aperture 384 formed
its center. Each planet gear 382 may be rotatably supported on an
associated one of the pins 378 and the second reduction carrier 364
may be positioned such that the gear teeth 382a of the planet gears
382 meshingly engage the gear teeth 360a of the second ring gear
360. The gear teeth 358a of the second sun gear 358 can be also
meshingly engaged with the gear teeth 382a of the planet gears
382.
[0091] The third reduction gear set 306 may be disposed within the
portion of the hollow cavity 212 defined by the second housing
portion 262 and may include a third sun gear 398, a third reduction
element or ring gear 400, a third set of planet gears 402 and a
third planet or reduction carrier 404. The third sun gear 398 may
be fixed for rotation with the second reduction carrier 364. The
third sun gear 398 can include a plurality of gear teeth 398a that
extend forwardly of the front face 406 of the second reduction
carrier 364.
[0092] The third ring gear 400 may be an annular structure, having
a plurality of gear teeth 400a formed along its interior diameter.
The gear teeth 400a may be heavily chamfered at the front face 412
of the third ring gear 400, but terminate abruptly at the rear face
414. More preferably, a heavy radius 407 may be formed onto the
front face 412 and the sides of each of the gear teeth 400a, with
the heavy radius 407 being employed rather than the heavy chamfer
as the heavy radius 407 on the gear teeth 400a provides for better
engagement between the third ring gear 400 and the third reduction
carrier 404. A plurality of sleeve engagement teeth 418 can be
formed into the outer perimeter of the third ring gear 400; the
sleeve engagement teeth 418 extend rearward toward the rear face
414 of the third ring gear 400 and terminate at a tip portion 420
that may be rounded and taper both rearwardly and inwardly. An
annular clip groove 422 may also be formed into the outer perimeter
of the third ring gear 400. In the example illustrated, the clip
groove 422 may be a rectangular slot having a pair of sidewalls
424. The clip groove 422 will be discussed in greater detail,
below.
[0093] The third reduction carrier 404 may be formed in the shape
of a flat cylinder, having plurality of pins 428 that extend from
its rearward face 430. A plurality of gear teeth 404a can be formed
into almost the entire outer perimeter of the third reduction
carrier 404, with a valley 404b being formed between each pair of
adjacent teeth 404a. Due to the spacing of the teeth 404a, one of
the valleys 404b (i.e., valley 404b') is relatively larger than the
remaining valleys 404b due to the omission of a tooth 404a in the
outer perimeter of the third reduction carrier 404. In the
particular embodiment illustrated, the gear teeth 404a of the third
reduction carrier 404 can be configured so as not to be meshingly
engagable with the gear teeth 382a of the second planet gears
382.
[0094] With brief additional reference to FIGS. 21 and 22, the
profile of the gear teeth 404a is illustrated in greater detail. As
shown, the rear face 430 of the third reduction carrier 404 may be
chamfered and a heavy radius 434 may be formed into each of sides
of the teeth 404a and valleys 404b. Each gear tooth 404a terminates
abruptly at the forward face 436 of the third reduction carrier
404.
[0095] Returning back to FIGS. 12, 13, 15, 18 and 23, the third set
of planet gears 402 may include a plurality of planet gears 438.
Each planet gear 438 may be generally cylindrical in shape, having
a plurality of gear teeth 438a formed into its outer perimeter and
a pin aperture 440 formed through its center. Each planet gear 438
may be rotatably supported on an associated one of the pins 428 and
the third reduction carrier 404 may be positioned such that the
gear teeth 438a of the planet gears 438 meshingly engage the gear
teeth 400a of the third ring gear 400. A raised portion 442 may be
formed into each of the front and rear faces of the planet gears
438 which inhibits the gear teeth 438a from rubbing on the third
reduction carrier 404 and creating dust or chips that would impair
the performance of the transmission assembly 12 and reduce its
operating life. A second thrust washer 450 may be disposed around
the third sun gear 398 and the teeth 398a of the third sun gear 398
can be meshingly engaged with the gear teeth 438a of the planet
gears 438. The second thrust washer 450 may include a plurality of
retaining tabs 452 that can be configured to engage corresponding
tab grooves 454 (FIG. 13) that can be formed in the inner surface
266 of body portion 246 of the transmission sleeve 200. The
retaining tabs 452 and the tab grooves 454 cooperate to inhibit
relative rotation between the second thrust washer 450 and the
transmission sleeve 200.
[0096] The output spindle assembly 20 may include a transmitting
means 458 for coupling a spindle 460 for rotation with the third
reduction carrier 404 so as to transmit drive torque from the
reduction gearset assembly 202 to the chuck 22. Such transmitting
means 458 are well known in the art and easily adapted to the
transmission assembly of the present disclosure. Accordingly, a
detailed discussion of the transmitting means 458 need not be
included herein.
[0097] With reference to FIGS. 13, 13a, 13b, 16, 17, 18 and 23
through 28, the speed selector mechanism 60 may be movable between
a first position 500, a second position 502 and a third position
504 and can include a switch portion 510 for receiving a speed
change input and an actuator portion 512 for manipulating the
reduction gearset assembly 202 in accordance with the speed change
input. The actuator portion 512 may be operatively coupled to the
reduction gearset assembly 202 and moves the second and third
reduction gear sets 304 and 306 between the active and inactive
modes in response to movement of the switch portion 510 between the
first, second and third positions 500, 502 and 504. In the
particular embodiment illustrated, the actuator portion 512 can
include a rotary selector cam 520, a plurality of wire clips 522
and a spring member 523. Each of the wire clips 522 may be formed
from a round wire which may be bent in the shape of a semi-circle
524 with a pair of tabs 526 extending outwardly from the
semi-circle 524 and positioned on about the centerline of the
semi-circle 524. The semi-circle 524 may be sized to fit within the
clip grooves 374 and 422 in the second and third ring gears 360 and
400, respectively. In this regard, the semi-circle 524 neither
extends radially outwardly of an associated one of the ring gears
(360, 400), nor binds against the sidewalls (376, 424) of the clip
grooves (374, 422). In the example provided, the sidewalls (376,
424) of the clip grooves (374, 422) are spaced apart about 0.05
inch and the diameter of the wire forming the wire clips 522 may be
about 0.04 inch.
[0098] The tabs 526 of the wire clips 522 extend outwardly of the
hollow cavity 212 into an associated one of the clip slots (284,
286) that may be formed into the transmission sleeve 200. The tabs
526 can be long enough so that they extend outwardly of the outer
surface 258 of the body 214 of the transmission sleeve 200, but not
so far as to extend radially outwardly of the portion of the first
clip slots 284 in the base 216 of the transmission sleeve 200.
Configuration of the wire clips 522 in this manner facilitates the
assembly of the transmission assembly 16, permitting the wire clips
522 to be installed to the second and third ring gears 360 and 400,
after which these assemblies can be inserted into the hollow cavity
212 along the longitudinal axis of the transmission sleeve 200.
[0099] With specific reference to FIGS. 13 and 27a through 27c, the
rotary selector cam 520 may include an arcuate selector body 530, a
switch tab 532 and a plurality of spacing members 534. A pair of
first cam slots 540a and 540b, a pair of second cam slots 544a and
544b, a spring aperture 546 and a guide aperture 548 can be formed
through the selector body 530. The selector body 530 may be sized
to engage the outside diameter of the body portion 246 of the
transmission sleeve 200 in a slip-fit manner. The guide aperture
548 may be generally rectangular in shape and sized to engage the
front and rear surfaces of the selector cam guide 250. The guide
aperture 548 may be considerably wider than the width of the
selector cam guide 250, being sized in this manner to permit the
rotary selector cam 520 to be rotated on the transmission sleeve
200 between a first rotational position, a second rotational
position and a third rotational position. The selector cam guide
250 and cooperates with the guide aperture 548 to limit the amount
by which the rotary selector cam 520 can be rotated on the
transmission sleeve 200, with a first lateral side of the selector
cam guide 250 contacting a first lateral side of the guide aperture
548 when the rotary selector cam 520 is positioned in the first
rotational position, and a second lateral side of the selector cam
guide 250 contacting a second lateral side of the guide aperture
548 when the rotary selector cam 520 is positioned in the third
rotational position.
[0100] Each of the first cam slots 540a and 540b may be sized to
receive one of the tabs 526 of the wire clip 522 that is engaged to
the second ring gear 360. In the particular embodiment illustrated,
first cam slot 540a can include a first segment 550, a second
segment 552 and an intermediate segment 554. The first segment 550
may be located a first predetermined distance away from a reference
plane 558 that may be perpendicular to the longitudinal axis of the
rotary selector cam 520 and the second segment 552 may be located a
second distance away from the reference plane 558. The intermediate
segment 554 couples the first and second segments 550 and 552 to
one another. The configuration of first cam slot 540b is identical
to that of first cam slot 540a, except that it is rotated relative
to the rotary selector cam 520 such that each of the first, second
and intermediate segments 550, 552 and 554 in the first cam slot
540b can be located 180.degree. apart from the first, second and
intermediate segments 550, 552 and 554 in the first cam slot
540a.
[0101] Each of the second cam slots 544a and 544b may be sized to
receive one of the tabs 526 of a corresponding one of the wire
clips 522. In the particular embodiment illustrated, second cam
slot 544a can include a first segment 560, a second segment 562, a
third segment 564 and a pair of intermediate segments 566 and 568.
The first and third segments 560 and 564 can be located a third
predetermined distance away from the reference plane and the second
segment 562 may be located a fourth distance away from the
reference plane 558. The intermediate segment 566a couples the
first and second segments 560 and 562 to one another and the
intermediate segment 568 couples the second and third segments 562
and 566 together. The configuration of second cam slot 544b is
identical to that of second cam slot 544a, except that it is
rotated relative to the rotary selector cam 520 such that each of
the first, second, third and intermediate segments 560, 562, 564
and 566 and 568 in the second cam slot 544b can be located
180.degree. apart from the first, second, third and intermediate
segments 560, 562, 564 and 566 and 568 in the second cam slot
544a.
[0102] With the tabs 526 of the wire clips 522 engaged to the first
cam slots 540a and 540b and the second cam slots 544a and 544b, the
rotary selector cam 520 may be rotated on the transmission sleeve
200 between the first, second and third positions 500, 502 and 504
to selectively engage and disengage the second and third ring gears
360 and 400 from the first and third reduction carriers 314 and
404, respectively. During the rotation of the rotary selector cam
520, the first cam slots 540a and 540b and the second cam slots
544a and 544b confine the wire tabs 526 of their associated wire
clip 522 and cause the wire tabs 526 to travel along the
longitudinal axis of the transmission sleeve 200 in an associated
one of the first and second clip slots 284 and 286. Accordingly,
the rotary selector cam 520 may be operative for converting a
rotational input to an axial output that causes the wire clips 522
to move axially in a predetermined manner. A lubricant (not
specifically shown) may be applied to the lubricant grooves 252
formed into body portion 246 of the transmission sleeve 200 may be
employed to lubricate the interface between the transmission sleeve
200 and the rotary selector cam 520.
[0103] Positioning the rotary selector cam 520 in the first
rotational position 500 causes the tabs 526 of the wire clip 522
that is engaged to the second ring gear 360 to be positioned in the
first segment 550 of the first cam slots 540a and 540b and the tabs
526 of the wire clip 522 that is engaged to the third ring gear 400
to be positioned in the first segment 560 of the second cam slots
544a and 544b. Accordingly, positioning of the rotary selector cam
520 in the first rotational position causes the second and third
ring gears 360 and 400 to be positioned in meshing engagement with
the second and third planet gears 362 and 402, respectively.
Simultaneously with the meshing engagement of the second and third
ring gears 360 and 400 with the second and third planet gears 362
and 402, the sleeve engagement teeth 370 and 418 of the second and
third ring gears 360 and 400, respectively, can be positioned in
meshing engagement with the first and second sets of ring
engagement teeth 254 and 256, respectively, to inhibit relative
rotation between the second and third ring gears 360 and 400 and
the transmission sleeve 200 to thereby providing the transmission
assembly 16 with a first overall gear reduction or speed ratio 570
as shown in FIG. 23. Those skilled in the art will understand that
the tip portion 272 of the teeth 268 of the first and second sets
of ring engagement teeth 254 and 256 and the tip portions 372 and
420 of the sleeve engagement teeth 370 and 418, respectively, can
be rounded and tapered so as to improve their capability for
meshing engagement in response to axial repositioning along a
longitudinal axis of the transmission assembly 16.
[0104] Positioning the rotary selector cam 520 in the second
rotational position 502 causes the tabs 526 of the wire clip 522
that is engaged to the second ring gear 360 to be positioned in the
first segment 550 of the first cam slots 540a and 540b and the tabs
526 of the wire clip 522 that is engaged to the third ring gear 400
to be positioned in the second segment 562 of the second cam slots
544a and 544b. Accordingly, positioning of the rotary selector cam
520 in second rotational position causes the second ring gear 360
to be in meshing engagement with the second planet gears 362 and
the third ring gear 400 in meshing engagement with both the third
planet gears 402 and the third reduction carrier 404. Positioning
of the rotary selector cam 520 in the second rotational position
502 also positions the sleeve engagement teeth 370 of the second
ring gear 360 in meshing engagement with the first set of ring
engagement teeth 254 while the sleeve engagement teeth 418 of the
third ring gear 400 can be not meshingly engaged with the second
set of ring engagement teeth 256. As such, relative rotation
between the second ring gear 360 and the transmission sleeve 200 is
inhibited, while relative rotation between the third ring gear 400
and the transmission sleeve 200 is permitted to thereby provide the
transmission assembly 16 with a second overall gear reduction or
speed ratio 572 as illustrated in FIG. 24.
[0105] Positioning the rotary selector cam 520 in the third
rotational position 504 causes the tabs 526 of the wire clip 522
that is engaged to the second ring gear 360 to be positioned in the
second segment 552 of the first cam slots 540a and 540b and the
tabs 526 of the wire clip 522 that is engaged to the third ring
gear 400 to be positioned in the third segment 564 of the second
cam slots 544a and 544b. Accordingly, positioning of the rotary
selector cam 520 in the third rotational position causes the second
ring gear 360 to be in meshing engagement with both the second
planet gears 362 and the first reduction carrier 314 while the
third ring gear 400 in meshing engagement with only the third
planet gears 402. Positioning the rotary selector cam 520 in the
third rotation position 504 also positions the sleeve engagement
teeth 370 on the second ring gear 360 out of meshing engagement
with the first set of ring engagement teeth 254 and the sleeve
engagement teeth 418 on the third ring gear 400 in meshing
engagement with the second sets of ring engagement teeth 256 to
inhibit relative rotation between the second ring gear 360 and the
transmission sleeve 200 and permit relative rotation between the
third ring gear 400 and the transmission sleeve 200 to provide the
transmission assembly 16 with a third overall gear reduction or
speed ratio 574.
[0106] In the example shown in FIGS. 13, 27b and 28, the spring
member 523 may be formed from a flat rectangular piece of spring
steel and can include a flattened Z-shaped portion 580 and a raised
portion 584. The flattened Z-shaped portion 580 may be configured
to wrap around two reinforcement bars 586 that extend into the
spring aperture 546, thereby permitting the raised portion 584 to
be maintained at a predetermined position and also to transmit a
spring force between the rotary selector cam 520 and the spring
member 523. With additional reference to FIG. 28, the raised
portion 584 of the spring member 523 may be sized to engage
internal notches 590 formed in the housing 592 of the output
spindle assembly 20. Lands 594 that can be circumferentially spaced
from the rotary selector cam 520 can be formed between the notches
590. When the output spindle assembly 20 is positioned over the
transmission assembly 16 and the speed selector mechanism 60 is
positioned in one of the first, second and third rotational
positions 500, 502 and 504, the raised portion 584 of the spring
member 523 engages an associated one of the notches 590. The force
that is generated by the spring member 523 when the raised portion
584 is moved downwardly toward the rotary selector cam 520 in
response to contact between the raised portion 584 and the land 594
acts to inhibit unintended rotation of the speed selector mechanism
60. Furthermore, placement of the raised portion 584 in a notch 590
provides the user with a tactile indication of the positioning of
the rotary selector cam 520.
[0107] In the particular embodiment illustrated in FIGS. 13 and
27c, switch portion 510 may include an arcuate band 600 having a
raised hollow and rectangular selector button 602 formed therein.
The arcuate band 600 may be formed from a plastic material and may
be configured to conform to the outer diameter of the rotary
selector cam 520. The open end of the selector button 602 may be
configured to receive the switch tab 532, thereby permitting the
switch portion 510 and the rotary selector cam 520 to be coupled to
one another in a fastenerless manner. The plurality of spacing
members 534 can be raised portions formed into the rotary selector
cam 520 that can be concentric to and extend radially outwardly
from the selector body 530. The spacing members 534 elevate the
arcuate band 600 to prevent the arcuate band from contacting the
wire tabs 526 in the first cam slots 540a and 540b. The spacing
members 534 may also be employed to selectively strengthen areas of
the rotary selector cam 520, such as in the areas adjacent the
first cam slots 540a and 540b.
[0108] Those skilled in the art will understand that the rotary
selector cam 520 (i.e., the first cam slots 540a and 540b and the
second cam slots 544a and 544b) could be configured somewhat
differently so as to cause the second ring gear 360 to meshingly
engage both the second planet gears 362 and the first reduction
carrier 314 while the third ring gear 400 meshingly engages both
the third planet gears 402 and the third reduction carrier 404.
Configuration in this manner provides the transmission assembly 16
with a fourth overall gear reduction or speed ratio.
[0109] Those skilled in the art will also understand that selector
mechanisms of other configurations may be substituted for the
selector mechanism 60 illustrated herein. These selector mechanisms
may include actuators that can be actuated via rotary or sliding
motion and may include linkages, cams or other devices that are
well known in the art to slide the second and third ring gears 360
and 400 relative to the transmission sleeve 200. Those skilled in
the art will also understand that as the second and third ring
gears 360 and 400 can be independently movable between the active
and inactive modes (i.e., the placement of one of the second and
third ring gears 360 and 400 does not dictate the positioning of
the other one of the second and third ring gears 360 and 400), the
switch mechanism 60 could also be configured to position the second
and third ring gears 360 and 400 independently of one another.
Clutch Mechanism
[0110] In FIGS. 23, 26 and 28 through 30, the clutch mechanism 18
may include a clutch member 700, an engagement assembly 702 and an
adjustment mechanism 704. The clutch member 700 may be an annular
structure that may be fixed to the outer diameter of the first ring
gear 310 and which extends radially outwardly therefrom. The clutch
member 700 may include the clutch face 316 that may be formed into
the front face 318 of the first ring gear 310. The outer diameter
of the clutch member 700 may be sized to rotate within the portion
of the hollow cavity 212 that is defined by the base 216 of the
transmission sleeve 200. With specific brief reference to FIG. 29,
the clutch face 316 of the example illustrated is shown to be
defined by a plurality of peaks 710 and valleys 712 that can be
arranged relative to one another to form a series of ramps that can
be defined by an angle of about 18.degree.. Those skilled in the
art will understand, however, that other clutch face configurations
may also be employed, such as a sinusoidally shaped clutch face
316' (FIG. 29a).
[0111] While the first ring gear 310 and the clutch member 700 have
been illustrated as a one piece (i.e., unitarily formed)
construction, those skilled in the art will understand that they
may be constructed otherwise. One such embodiment is illustrated in
FIG. 29b wherein the first ring gear 310' may include an annular
collar 1000 and a plurality of tab apertures 1002. The annular
collar 1000 may include a plurality of ramps 1004 that have dual
sloping sides, but is otherwise flat. The first ring gear 310' is
otherwise identical to the first ring gear 310. An annular damper
1008 abuts the annular collar 1000 and can include a plurality of
tab members 1010 that engage the tab apertures 1002 in the first
ring gear 310' to prevent the damper 1008 from rotating relative to
the first ring gear 310'. The damper 1008 can include a body
portion 1012 that may be configured to match the contour of the
annular collar 1000 and as such, can include a plurality of mating
ramped portions 1014 that can be configured to engage each of the
ramps 1004. The damper 1008 may be formed from a suitable impact
dampening material, such as acetyl. The clutch member 700', which
may be an annular member that may be formed from a wear resistant
material, such as hardened 8620 steel, may be disposed over the
damper 1008. Like the damper 1008, the clutch member 700' can
include a plurality of tab members 1020, which lock into the tab
apertures 1002 to prevent rotation relative to the first ring gear
310', and a plurality of mating ramped portions 1022. The mating
ramped portions 1022 of the clutch member 700', however, matingly
engage the mating ramped portions 1014 of the damper 1008. While
the construction in this manner is more expensive relative to the
previously described embodiment, it is more tolerant of high impact
forces that can be associated with the operation of the clutch
mechanism 18.
[0112] In the particular embodiment illustrated, the engagement
assembly 702 can include a pin member 720, a follower spring 722
and a follower 724. The pin member 720 can include a cylindrical
body portion 730 having an outer diameter that may be sized to
slip-fit within the second portion 278 of the actuator aperture 274
that is formed into the pin housing portion 248 of the transmission
sleeve 200. The pin member 720 also can include a tip portion 732
and a head portion 734. The tip portion 732 may be configured to
engage the adjustment mechanism 704 and in the example shown, is
formed into the end of the body portion 730 of the pin member 720
and defined by a spherical radius. The head portion 734 may be
coupled to the end of the body portion 730 opposite the tip portion
732 and may be shaped in the form of a flat cylinder or barrel that
is sized to slip fit within the first portion 276 of the actuator
aperture 274. Accordingly, the head portion 734 prevents the pin
member 720 from being urged forwardly out of the actuator aperture
274.
[0113] The follower spring 722 may be a compression spring whose
outside diameter may be sized to slip fit within the first portion
276 of the actuator aperture 274. The forward end of the follower
spring 722 contacts the head portion 734 of the pin member 720,
while the opposite end of the follower spring 722 contacts the
follower 724. The end portion 740 of the follower 724 may be
cylindrical in shape and sized to slip fit within the inside
diameter of the follower spring 722. In this regard, the end
portion 740 of the follower acts as a spring follower to prevent
the follower spring 722 from bending over when it is compressed.
The follower 724 also can include a follower portion 744 having a
cylindrically shaped body portion 746, a tip portion 748 and a
flange portion 750. The body portion 746 may be sized to slip fit
within the first portion 276 of the actuator aperture 274. The tip
portion 748 may be configured to engage the clutch face 316 and in
the example shown, is formed into the end of the body portion 746
of the follower 724 and defined by a spherical radius. The flange
portion 750 may be formed at the intersection between the body
portion 746 and the end portion 740. The flange portion 750 may be
generally flat and configured to receive a biasing force that may
be exerted by the follower spring 722.
[0114] The adjustment mechanism 704 may also include an adjustment
structure 760 and a setting collar 762. The adjustment structure
760 may be shaped in the form of a generally hollow cylinder that
may be sized to fit a housing portion 766 of the output spindle
assembly 20. The adjustment structure 760 can include an annular
face 768 into which an adjustment profile 770 may be formed. The
adjustment profile 770 can include a first adjustment segment 772,
a last adjustment segment 774, a plurality of intermediate
adjustment segments 776 and a ramp section 778 between the first
and last adjustment segments 772 and 774. In the embodiment
illustrated, a second ramp section 779 is included between the last
intermediate adjustment segment 776z and the last adjustment
segment 774. Also in the particular embodiment illustrated, the
portion of the adjustment profile 770 from the first adjustment
segment 772 through the last one of the intermediate adjustment
segments 776z is formed as a ramp having a constant slope.
Accordingly, a follower 780 that is coupled to the housing portion
766 of the output spindle assembly 20 may be biased radially
outwardly toward the inside diameter of the adjustment structure
760 where it acts against the plurality of detents 782 that can be
formed into the adjustment mechanism 704 (e.g., in the setting
collar 762). The follower 724 and plurality of detents 782
cooperate to provide the user of tool 10 with a tactile indication
of the position of the adjustment profile 770 as well as inhibit
the free rotation of the adjustment structure 760 so as to maintain
the position of the adjustment profile 770 at a desired one of the
adjustment segments 772, 774 and 776.
[0115] The setting collar 762 may be coupled to the exterior of the
adjustment structure 760 and may include a plurality of raised
gripping surfaces 790 that permit the user of the tool 10 to
comfortably rotate both the setting collar 762 and the adjustment
structure 760 to set the adjustment profile 770 at a desired one of
the adjustment segments 772, 774 and 776. A setting indicator 792
may be employed to indicate the position of the adjustment profile
770 relative to the housing portion 766 of the output spindle
assembly 20. In the example provided, the setting indicator 792 can
include an arrow 794 formed into the housing portion 766 of the
output spindle assembly 20 and a scale 796 that is marked into the
circumference of the setting collar 762.
[0116] During the operation of the tool 10, an initial drive torque
is transmitted by the motor pinion 46 from the motor assembly 14 to
the first set of planet gears 312 causing the first set of planet
gears 312 to rotate. In response to the rotation of the first set
of planet gears 312, a first intermediate torque is applied against
the first ring gear 310. Resisting this torque is a clutch torque
that is applied by the clutch mechanism 18. The clutch torque
inhibits the free rotation of the first ring gear 310, causing the
first intermediate torque to be applied to the first reduction
carrier 314 and the remainder of the reduction gearset assembly 202
so as to multiply the first intermediate torque in a predetermined
manner according to the setting of the switch mechanism 60. In this
regard, the clutch mechanism 18 biases the first reduction gear set
302 in the active mode.
[0117] The magnitude of the clutch torque is dictated by the
adjustment mechanism 704, and more specifically, the relative
height of the adjustment segment 772, 774 or 776 that is in contact
with the tip portion 732 of the pin member 720. Positioning of the
adjustment mechanism 704 at a predetermined one of the adjustment
segments 772, 774 or 776 pushes the pin member 720 rearwardly in
the actuator aperture 274, thereby compressing the follower spring
722 and producing the a clutch force. The clutch force is
transmitted to the flange portion 750 of the follower 724, causing
the tip portion 748 of the follower 724 to engage the clutch face
316 and generating the clutch torque. Positioning of the tip
portion 748 of the follower 724 in one of the valleys 712 in the
clutch face 316 operates to inhibit rotation of the first ring gear
310 relative to the transmission sleeve 200 when the magnitude of
the clutch torque exceeds the first intermediate torque. When the
first intermediate torque exceeds the clutch torque, however, the
first ring gear 310 is permitted to rotate relative to the
transmission sleeve 200. Depending upon the configuration of the
clutch face 316, rotation of the first ring gear 310 may cause the
clutch force to increase a sufficient amount to resist further
rotation. In such situations, the first ring gear 310 will rotate
in an opposite direction when the magnitude of the first
intermediate torque diminishes, permitting the tip portion 748 of
the follower 724 to align in one of the valleys 712 in the clutch
face 316. If rotation of the first ring gear 310 does not cause the
clutch force to increase sufficiently so as to fully resist
rotation of the first ring gear 310, the first reduction gearset
302 will rotate so as to limit the transmission of torque to the
first reduction carrier 314.
[0118] Configuration of the clutch mechanism 18 in this manner is
highly advantageous in that the clutch torque is sized to resist
the first intermediate torque, as opposed to the output torque of
the tool 10 that is generated by the multi-reduction transmission
assembly 16 and transmitted through the chuck 22. In this regard,
the clutch mechanism 18 may be sized in a relatively small manner,
thereby improving the ability with which it may be incorporated or
packaged into the tool 10. Furthermore, as the speed or gear ratios
can be changed after or down stream of the first ring gear 310, the
clutch mechanism 18 is operable over a relatively large span of
output torques. In comparison with conventional clutch mechanisms
that operate to limit the output torque of a transmission, these
devices can be typically operable over a relatively narrow torque
band, necessitating a change in their clutch spring if a
considerable shift in the magnitude of the output torque is
desired. In contrast, the clutch mechanism 18 of the present
disclosure can accommodate a considerable shift in the magnitude of
the output torque of the tool 10 by simply operating the
transmission assembly 16 in a different (i.e., lower or higher)
gear ratio.
[0119] In the operation of rotary power tools such as tool 10, it
is frequently desirable to change between two clutch settings, as
when the tool 10 is used to both drill a hole and thereafter
install a screw in that hole. Accordingly, the adjustment mechanism
704 may be rotated relative to the output spindle assembly 20 to
position the adjustment mechanism 704 at a desired one of the
adjustment segments 772, 774 and 776 to perform the first operation
and thereafter rotated to a second one of the adjustment segments
772, 774 and 776 to perform the second operation. In contrast to
the known clutch arrangements, the adjustment mechanism 704 of the
present disclosure is configured such that the adjustment structure
760 and the setting collar 762 can be rotatable through an angle of
360.degree.. Assuming the adjustment structure 760 to be positioned
at an intermediate adjustment segment 776x, rotation of the
adjustment mechanism 704 through an angle of 360.degree. would
rotate the adjustment structure 760 past the other intermediate
adjustment segments 776, as well as the first and last adjustment
segments 772 and 774 and the ramp section 778 such that the
adjustment structure 760 would again be positioned at the
intermediate adjustment segment 776x. The feature is especially
convenient when it is necessary to change the clutch setting
between a relatively high clutch setting and a relatively low
clutch setting. In this regard, the ramp section 778 permits the
setting collar 762 (and adjustment structure 760) to be rotated
from highest clutch setting, corresponding to the last adjustment
segment, to the lowest clutch setting, corresponding to the first
clutch setting, without positioning the clutch mechanism 18 in one
of the intermediate clutch settings. Accordingly, the user of the
tool 10 is able to vary the clutch setting from its maximum setting
to its minimum setting (and vice versa) by rotating the setting
collar 762 a relatively small amount.
[0120] While the adjustment profile 770 has been described thus far
as having a constant slope, those skilled in the art will
appreciate that the disclosure, in its broader aspects, may be
constructed somewhat differently. For example, the adjustment
profile 770' may be formed such that each of the first, last and
intermediate adjustment segments 772', 774' and 776' is detented as
illustrated in FIG. 31. In this arrangement, the detents 782 in the
adjustment structure 760 and the follower 780 in the housing
portion 766 of the output spindle assembly 20 can be unnecessary as
the adjustment segments 772', 774' and 776' will cooperate with the
engagement 702 to provide the user of the tool 10 with a tactile
indication of the position of the adjustment profile 770', as well
as inhibit the free rotation of the adjustment structure 760.
[0121] Another example is illustrated in FIG. 32 wherein the
adjustment profile 770'' is generally similar to the adjustment
profile 770 except that the ramp section 779 has been omitted so
that the last intermediate adjustment segment 776z is immediately
adjacent the last adjustment segment 774.
[0122] While the transmission assembly 16 has been described thus
far as including a three-stage, three speed transmission, those of
ordinary skill in the art will appreciate from this disclosure that
the disclosure, in its broader aspects, may be constructed somewhat
differently. For example, another (i.e., fourth) or different speed
ratio may be provided by operating two of the reduction gear sets
(e.g., both the second and third reduction gear sets 304 and 306)
in the inactive mode. Those of ordinary skill in the art will also
appreciate from this disclosure that the second reduction gear set
304 may be placed in the inactive mode by coupling the second ring
gear 360 to the second planet carrier 364 (rather than to the first
planet carrier 314) and/or that the third reduction gear set 306
may be placed in the inactive mode by coupling the third ring gear
400 to the second planet carrier 364 (rather than to the third
planet carrier 404).
[0123] Other transmission assemblies constructed in accordance with
the teachings of the present disclosure are illustrated in FIGS. 33
through 56. Generally speaking, these configurations are similar to
that which is described above and illustrated in detail in FIGS. 23
through 25. Accordingly, similar or corresponding elements of the
alternately constructed transmission assemblies are identified by
similar reference numerals as were used to describe the
transmission assembly 16.
[0124] In the example of FIGS. 33 through 35, the transmission
assembly 16-1 may include one or more movable elements which may be
employed to selectively couple the ring gears 360-1 and 400-1 of
the second and third reduction gear sets 304-1 and 306-1,
respectively, to the transmission sleeve 200-1. The movable
elements, which may be pins 2000 and 2002, may be housed in the
transmission sleeve 200-1 and extend through corresponding
apertures 2004 and 2006, respectively, in the transmission sleeve
200-1 and may be translated into and out of engagement with a
respective one of the ring gears (i.e., ring rears 360-1 and
400-1). In the example provided, each of the ring gears 360-1 and
400-1 can include teeth 370-1 and 418-1, respectively, (similar to
teeth 370 and 418, respectively, that are shown in FIG. 23) that
are spaced apart by a sufficient distance to receive the pins 2000
and 2002, respectively, therebetween. With the ring gears 360-1 and
400-1 locked to the transmission sleeve 200-1 as shown in FIG. 33,
the transmission assembly 16-1 operates in a manner that is similar
to that which is described in conjunction with FIG. 23, above.
[0125] In FIG. 34, the transmission assembly 16-1 is shown in a
second overall speed or gear reduction ratio, wherein the first and
second reduction gear sets 302-1 and 304-1 are in an active mode
and the third reduction gear set 306-1 is in an inactive mode. The
third reduction gear set 306-1 may be inactivated by moving (e.g.,
translating) the pin 2002 out of engagement with the teeth 418-1 of
the ring gear 400-1 and engaging the third planet carrier 404-1 to
the third ring gear 400-1. This latter task may be accomplished,
for example, by sliding the third planet carrier 404-1 toward and
into engagement with the third ring gear 400-1. Any appropriate
means may be employed to engage the third planet carrier 404-1 and
the third ring gear 400-1 to one another, including friction (i.e.,
frictional engagement), or features, such as pins or teeth, that
may be formed on one or both of the third planet carrier 404-1 and
the third ring gear 400-1. In the example provided, teeth 2010,
which are formed on the third ring gear 400-1, engage mating teeth
2012 that are formed on the planet carrier 404-1.
[0126] In FIG. 35, the transmission assembly 16-1 is shown in a
third overall speed or gear reduction ratio, wherein the first and
third reduction gear sets 302-1 and 306-1 are in an active mode and
the second reduction gear set 304-1 is in an inactive mode. The
second reduction gear set 304-1 may be inactivated by moving (e.g.,
translating) the pin 2000 out of engagement with the teeth 370-1 of
the ring gear 360-1 and engaging the first planet carrier 314-1 to
the second ring gear 360-1.
[0127] This latter task may be accomplished, for example, by
sliding the first planet carrier 314-1 toward and into engagement
with the second ring gear 360-1. Any appropriate means may be
employed to engage the first planet carrier 314-1 and the second
ring gear 360-1 to one another, including friction (i.e.,
frictional engagement), or features, such as pins or teeth, that
may be formed on one or both of the first planet carrier 314-1 and
the second ring gear 360-1. In the example provided, teeth 2014,
which are formed on the second ring gear 360-1, engage mating teeth
2016 that are formed on the first planet carrier 314-1.
[0128] Those skilled in the art will appreciate that although the
movable elements (e.g., pins 2000 and 2002) have been illustrated
as translating in a direction that is generally perpendicular to
the longitudinal axis of the transmission assembly 16-1, the
disclosure in its broadest aspects, however, may be configured
somewhat differently. For example, each of the movable elements may
be translated in a direction that is generally parallel to the
longitudinal axis of the transmission 16-1 between a first
position, which permits the movable element to engage a feature on
a respective one of the ring gears, and a second position, which
aligns the movable element to an annular groove or a smooth,
featureless portion on the respective ring gear so that the movable
element does not inhibit the rotation of the respective ring
gear.
[0129] The transmission assembly 16-2 of FIGS. 36 through 38 is
generally similar to the embodiment of FIGS. 33 through 35, except
that the first set of planet gears 344 of the first reduction gear
set 302-2 and the third set of planet gears 402 of the third
reduction gear set 306-2 remain in a fixed position relative to the
first and third ring gears 310 and 400-1, respectively, regardless
of the position of the first and third planet carriers 314-2 and
404-2, respectively. The first planet carrier 314-2 can be in a
rearward position (shown in FIG. 36) when the second reduction gear
set 304-2 is in an active mode and a forward position when the
second reduction gear set 304-2 is in an inactive mode. The third
planet carrier 404-2 can be in a forward position (shown in FIG.
36) when the third reduction gear set 306-2 is in an active mode
and a rearward position (shown in FIG. 37) when the third reduction
gear set 306-2 is in an inactive mode. In contrast, the first set
of planet gears 344 and the third set of planet gears 402 slide
with the first and third planet carriers 314-1 and 404-1,
respectively, in the embodiment of FIGS. 33 through 35.
[0130] With reference to FIGS. 39 through 41, the transmission
assembly 16-3 may include one or more locking elements that may be
selectively employed to lock the second and third ring gears 360-3
and 400-3 to the first and third planet carriers 314-3 and 404-3,
respectively. The locking elements may include, for example first
and second idler gears 2050 and 2052, for example, that may have
teeth 2050a and 2052a, respectively, that may be meshingly engaged
to teeth 314a and 404a, respectively, that are formed on the first
and third planet carriers 314-3 and 404-3, respectively. The
locking elements 2050 and 2052 may be rotatably supported on pins
2054 and 2056, respectively, that may be mounted to another portion
of the power tool, such as the transmission sleeve 200-3. In a
first speed reduction ratio, which is illustrated in FIG. 39, the
second and third ring gears 360-3 and 400-3 are fixed to the
transmission sleeve 200-3, for example by teeth 370-3 and 418-3,
respectively, on the outer diameter of the ring gears 360-3 and
400-3, respectively, and mating teeth 254-3 and 256-3,
respectively, that are formed on the interior of the transmission
sleeve 200-3.
[0131] In FIG. 40, the transmission assembly 16-3 is shown in a
second overall speed or gear reduction ratio, wherein the first and
second reduction gear sets 302-3 and 304-3 are in an active mode
and the third reduction gear set 306-3 is in an inactive mode. The
third reduction gear set 306-3 may be inactivated by translating
the third ring gear 400-3 such that the teeth 418-3 are not engaged
with the mating teeth 256-3 on the transmission sleeve 200-3 but
rather with the teeth 2052a of the second idler gear 2052.
Translation of the third ring gear 400-3 may also cause the third
planet carrier 404-3 to slide on the second idler gear 2052 and/or
the third set of planet gears 402 to slide relative to the
transmission sleeve 200-3.
[0132] In FIG. 41, the transmission assembly 16-3 is shown in a
third overall speed or gear reduction ratio, wherein the first and
third reduction gear sets 302-3 and 306-3 are in an active mode and
the second reduction gear set 304-3 is in an inactive mode. The
second reduction gear set 304-3 may be inactivated by translating
the second ring gear 360-3 such that the teeth 370-3 are not
engaged with the mating teeth 254-3 on the transmission sleeve
200-3 but rather with the teeth 2050a of the first idler gear 2050.
Translation of the second ring gear 360-3 may also cause the first
planet carrier 314-3 to slide on the first idler gear 2050 and/or
the first set of planet gears 344 to slide relative to the
transmission sleeve 200-3.
[0133] With reference to FIGS. 42 through 44, the transmission
assembly 16-4 may be configured such that portions of the second
reduction gear set 304-4 and the third reduction gear set 306-4 may
slide into and out of locking engagement with another element of
the transmission assembly 16-4. In the example provided, the second
and third sets of planet gears 382-4 and 402-4, respectively, may
be translated between a first position, in which they meshingly
engage an associated ring gear, and a second position, in which
they non-rotatably engage an associated planet carrier as well as
meshingly engage the associated ring gear. In a first speed
reduction ratio, which is illustrated in FIG. 42, the second and
third ring gears 360-4 and 400-4 are fixed to the transmission
sleeve 200-4, in a manner that is similar to that which was
described above in conjunction with FIG. 33.
[0134] In FIG. 43, the transmission assembly 16-4 is shown in a
second overall speed or gear reduction ratio, wherein the first and
second reduction gear sets 302-4 and 304-4 are in an active mode
and the third reduction gear set 306-4 is in an inactive mode. The
third reduction gear set 306-4 may be inactivated by translating
the pin 2002 out of engagement with the teeth 418-1 on the third
ring gear 400-4 and translating the third set of planet gears 402-4
into engagement with the third planet carrier 404-4 such that the
third set of planet gears 402-4 are maintained in a stationary
condition relative to the third planet carrier 404-4. Engagement of
the third set of planet gears 402-4 to the third planet carrier
404-4 may be made in any desired manner, such as frictional
engagement or through mating features. In the example provided,
teeth 2076 are formed into an axial end face of the third set of
planet gears 402-4 and mating teeth 2078 are formed on the third
planet carrier 404-4 which meshingly engage the teeth 2076 on the
third set of planet gears 402-4. The third ring gear 400-4 may
optionally translate with the third set of planet gears 402-4.
[0135] In FIG. 44, the transmission assembly 16-4 is shown in a
third overall speed or gear reduction ratio, wherein the first and
third reduction gear sets 302-4 and 306-4 are in an active mode and
the second reduction gear set 304-4 is in an inactive mode. The
second gear set 304-4 may be inactivated by translating the pin
2000 out of engagement with the teeth 370-1 of the second ring gear
360-4 and translating the second set of planet gears 382-4 into
engagement with the first planet carrier 314-4 such that the second
set of planet gears 382-4 are maintained in a stationary condition
relative to the first planet carrier 314-4. Engagement of the
second set of planet gears 382-4 to the first planet carrier 314-4
may be made in any desired manner, such as frictional engagement or
through mating features. In the example provided, teeth 2072 are
formed into an axial end face of the second set of planet gears
382-4 and mating teeth 2074 are formed on the first planet carrier
314-4 which meshingly engage the teeth 2072 on the second set of
planet gears 382-4. The second ring gear 360-4 may optionally
translate with the second set of planet gears 382-4.
[0136] In FIGS. 45 through 47 yet another transmission assembly
16-5 constructed in accordance with the teachings of the present
disclosure is illustrated. The transmission assembly 16-5 may
include movable elements, such as pins 2000 and 2002, which may be
employed to lock the second and third ring gears 360-5 and 400-5,
respectively, in a stationary position, and locking elements, such
as first and second idler gears 2050-5 and 2052-5, respectively,
that may be employed to lock each of the second and third ring
gears 360-5 and 400-5, respectively, to the first and third planet
carriers 314-5 and 404-5, respectively. With specific reference to
FIG. 45, the transmission 16-5 is illustrated in a first overall
speed reduction or gear ratio wherein the pins 2050-5 and 2052-5
may be positioned in engagement with teeth 370-1 and 418-1,
respectively, on the second and third ring gears 360-5 and 400-5,
respectively, to maintain the second and third ring gears 360-5 and
400-5 in a stationary position. In this condition, the first and
second idler gears 2050-5 and 2052-5 may be disengaged from the
teeth 370-1 and 418-1 of the second and third ring gears 360-5 and
400-5, respectively, as well as from the teeth 314a and 404a of the
first and third planet carriers 314-5 and 404-5.
[0137] In FIG. 46, the transmission assembly 16-5 is illustrated in
a second overall speed reduction or gear ratio wherein the first
and second reduction gear sets 302-5 and 304-5, respectively, are
in an active mode and the third reduction gear set 306-5 is in an
inactive mode. The third reduction gear set 306-5 may be
inactivated by translating the pin 2002 out of engagement with the
teeth 418-1 of the third ring gear 400-5 and moving the idler gear
2052-5, e.g., by translation and/or rotation, into a position where
the teeth 2052a of the idler gear 2052-5 meshingly engage both the
teeth 418-1 of the third ring gear 400-5 and the teeth 404a of the
third planet carrier 404-5.
[0138] In FIG. 47, the transmission assembly 16-5 is illustrated in
a third overall speed reduction or gear ratio wherein the first and
third reduction gear sets 302-5 and 306-5 are in an active mode and
the second reduction gear set 304-5 is in an inactive mode. The
second reduction gear set 304-5 may be inactivated by translating
the pin 2000 out of engagement with the teeth 370-1 of the second
ring gear 360-5 and moving the idler gear 2050-5, e.g., by
translation and/or rotation, into a position where the teeth 2050a
of the idler gear 2050-5 meshingly engage both the teeth 370-1 of
the second ring gear 360-5 and the teeth 314a of the first planet
carrier 314-5.
[0139] In FIGS. 48 through 50 yet another transmission assembly
16-6 constructed in accordance with the teachings of the present
disclosure is illustrated. The transmission assembly 16-6 may
include movable elements, such as idler gears 2050-6 and 2052-6
which may be employed to lock the ring gears 360-6 and 400-6,
respectively, into a stationary position relative to the
transmission sleeve 200-6 or to lock the second and third ring
gears 360-6 and 400-6 for rotation with the first and third planet
carriers 314-6 and 404-6, respectively. With specific reference to
FIG. 48, the transmission assembly 16-6 is illustrated in a first
overall speed reduction or gear ratio wherein the idler gears
2050-6 and 2052-6 are positioned to maintain the second and third
ring gears 360-6 and 400-6 in a stationary position. The idler
gears 2050-6 and 2052-6 may engage a feature, such as teeth 2090
and 2092, respectively, that is formed on another part of the power
tool, such as the housing 12-6 or the transmission sleeve 200-6,
which inhibits their rotation and thereby locks a respective one of
the ring gears in a stationary position.
[0140] In FIG. 49, the transmission assembly 16-6 is illustrated in
a second overall speed reduction or gear ratio wherein the first
and second reduction gear sets 302-6 and 304-6 are in an active
mode and the third reduction gear set 306-6 is in an inactive mode.
The third reduction gear set 306-6 may be inactivated by
translating the idler gear 2052-6, e.g., along the journal pin
2096, into a position where the teeth 2052a of the idler gear
2052-6 do not engage the tooth or teeth 2092 but engage both the
teeth 418-1 of the third ring gear 400-6 and the teeth 404a of the
third planet carrier 404-6.
[0141] In FIG. 50, the transmission assembly 16-6 is illustrated in
a third overall speed reduction or gear ratio, wherein the first
and third reduction gear sets 302-6 and 306-6 are in an active
mode, and the second reduction gear set 304-6 is in an inactive
mode. The second reduction gear set 304-6 may be inactivated by
translating the idler gear 2050, e.g., along the journal pin 2096,
into a position where the teeth 2050a of the idler gear 2050-6 do
not engage the tooth or teeth 2090 but engage both the teeth 370-1
of the second ring gear 360-6 and the teeth 314a of the first
planet carrier 314-6.
[0142] In FIGS. 51 through 53 a further transmission assembly 16-7
constructed in accordance with the teachings of the present
disclosure is illustrated. The transmission assembly 16-7 may
include movable, intermediate locking elements, such as collars
3000 and 3002, which may be employed to lock the second and third
ring gears 360-7 and 400-7 in a stationary position or for rotation
with the first and third planet carriers 314-7 and 404-7,
respectively. With specific reference to FIG. 51, the transmission
16-7 is illustrated in a first overall speed reduction or gear
ratio wherein the collars 3000 and 3002 are positioned to maintain
the second and third ring gears 360-7 and 400-7 in a stationary
position. The collars 3000 and 3002 may engage the teeth 370-1 and
418-1 of the second and third ring gears 360-7 and 400-7 and may
include features, such as teeth or pins 3004 and 3006,
respectively, that may engage a mating feature, such as teeth or
apertures 3008, that may be formed into another portion of the
power tool, such as the transmission sleeve 200-7, to thereby lock
a respective one of the ring gears in a stationary position.
Alternatively, the pins 3004 and 3006 of the collars 3000 and 3002,
respectively, may extend through apertures (not shown) that can be
formed in the second and third ring gears 360-7 and 400-7,
respectively.
[0143] In FIG. 52, the transmission assembly 16-7 is illustrated in
a second overall speed reduction or gear ratio wherein the first
and second reduction gear sets 302-7 and 304-7 are in an active
mode and the third reduction gear set 306-7 is in an inactive mode.
The third reduction gear set 306-7 may be inactivated by
translating the collar 3002 into a position where the pins 3006
disengage the apertures 3008 in the transmission sleeve 200-7 and
the collar 3002 engages both the teeth 418-1 of the third ring gear
400-7 and the third planet carrier 404-7. Any appropriate means may
be employed to engage the collar 3002 and the third planet carrier
404-7 to one another, including friction (i.e., frictional
engagement), or features, such as pins or teeth, that may be formed
on one or both of the third planet carrier 404-7 and the collar
3002. In the example provided, the collar 3002 frictionally engages
the planet carrier 404-7.
[0144] In FIG. 53, the transmission assembly 16-7 is illustrated in
a third overall speed reduction or gear ratio wherein the first and
third reduction gear sets 302-7 and 306-7 are in an active mode and
the second reduction gear set 304-7 is in an inactive mode. The
second reduction gear set 304-7 may be inactivated by translating
the collar 3000 into a position where the pins 3004 disengage the
apertures 3008 in the transmission sleeve 200-7 and the collar 3000
engages both the teeth 370-1 of the second ring gear 360-7 and the
first planet carrier 314-7. Any appropriate means may be employed
to engage the collar 3000 and the first planet carrier 314-7 to one
another, including friction (i.e., frictional engagement), or
features, such as pins or teeth, that may be formed on one or both
of the first planet carrier 314-7 and the collar 3000. In the
example provided, the collar 3000 frictionally engages the first
planet carrier 314-7.
[0145] The embodiment of FIGS. 54 through 56 is generally similar
to that of FIGS. 51 through 53, except that each of the collars
3000-8 and 3002-8 can include teeth 3050 and 3052, respectively,
that meshingly engage the teeth 370-8 and 418-8, respectively, that
can be formed on the second and third ring gears 360-8 and 400-8,
respectively. As shown in FIG. 56, the collar 3000-8 may be
translated into a position where the teeth 3050 meshingly engage
both the teeth 370-8 of the second ring gear 360-8 and the teeth
314a of the first planet carrier 314-8 to thereby place the second
reduction gear set 304-8 into the inactive mode. Similarly, the
collar 3002-8 may be translated into a position where the teeth
3052 engage both the teeth 418-8 of the third ring gear 400-8 and
the teeth 404a of the third planet carrier 404-8 to thereby place
the third reduction gear set 306-8 into the inactive mode as is
shown in FIG. 55. The first reduction gear set 302-8 is in the
active mode in each of FIGS. 54 through 56.
[0146] While the disclosure has been described in the specification
and illustrated in the drawings with reference to various
embodiments, it will be understood by those skilled in the art that
various changes may be made and equivalents may be substituted for
elements thereof without departing from the scope of the disclosure
as defined in the claims. Furthermore, the mixing and matching of
features, elements and/or functions between various embodiments is
expressly contemplated herein so that one of ordinary skill in the
art would appreciate from this disclosure that features, elements
and/or functions of one embodiment may be incorporated into another
embodiment as appropriate, unless described otherwise, above.
Moreover, many modifications may be made to adapt a particular
situation or material to the teachings of the disclosure without
departing from the essential scope thereof. Therefore, it is
intended that the disclosure not be limited to the particular
embodiment illustrated by the drawings and described in the
specification as the best mode presently contemplated for carrying
out this disclosure, but that the disclosure will include any
embodiments falling within the foregoing description and the
appended claims.
[0147] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not
intended to be exhaustive or to limit the disclosure. Individual
elements or features of a particular embodiment are generally not
limited to that particular embodiment, but, where applicable, are
interchangeable and can be used in a selected embodiment, even if
not specifically shown or described. The same may also be varied in
many ways. Such variations are not to be regarded as a departure
from the disclosure, and all such modifications are intended to be
included within the scope of the disclosure.
* * * * *