U.S. patent application number 17/412448 was filed with the patent office on 2022-03-03 for retention flange for power tool.
The applicant listed for this patent is Black & Decker Inc.. Invention is credited to Levi G. BOWERS, Benjamin R. HITTIE, Christopher T. KING, Daniel F. NACE, James H. STILES, III.
Application Number | 20220063047 17/412448 |
Document ID | / |
Family ID | 1000005864625 |
Filed Date | 2022-03-03 |
United States Patent
Application |
20220063047 |
Kind Code |
A1 |
NACE; Daniel F. ; et
al. |
March 3, 2022 |
RETENTION FLANGE FOR POWER TOOL
Abstract
A power tool is provided including an output spindle rotatably
driven by an electric motor. The output spindle defines a
longitudinal axis and includes a threaded portion near a distal end
and an annular rim. A retention flange is provided including a
radially-oriented disc-shaped portion having a center through-hole
through which the output spindle extends and a cylindrical wall
peripherally extending from the disc-shaped portion around the
output spindle. The disc-shaped portion is located between the
distal end and the annular rim, and the cylindrical wall extends
around the annular rim. At least one spring member is disposed
between the annular rim and the retention flange. A retention
member is provided to restrain an axial displacement of the
retention flange away from the annular rim due to the biasing force
of the spring member.
Inventors: |
NACE; Daniel F.; (Towson,
MD) ; STILES, III; James H.; (Baltimore, MD) ;
HITTIE; Benjamin R.; (Baltimore, MD) ; KING;
Christopher T.; (Catonsville, MD) ; BOWERS; Levi
G.; (Manchester, MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Black & Decker Inc. |
New Britain |
CT |
US |
|
|
Family ID: |
1000005864625 |
Appl. No.: |
17/412448 |
Filed: |
August 26, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
63071416 |
Aug 28, 2020 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B25F 5/001 20130101;
B24B 23/022 20130101; F16F 1/32 20130101 |
International
Class: |
B24B 23/02 20060101
B24B023/02; B25F 5/00 20060101 B25F005/00 |
Claims
1. A power tool comprising: a housing; an electric motor housed
within the housing; an output spindle rotatably driven by the
electric motor, wherein the output spindle defines a longitudinal
axis and includes a threaded portion near a distal end thereof and
an annular rim integrally extending radially therefrom at a
distance from the threaded portion; a retention flange including a
radially-oriented disc-shaped portion having a center through-hole
through which the output spindle extends and a cylindrical wall
peripherally extending from the disc-shaped portion around the
output spindle, wherein the disc-shaped portion is located between
the distal end and the annular rim, and the cylindrical wall
extends around the annular rim; at least one spring member engaging
a first surface of the annular rim on one end and the disc-shaped
portion on another end to bias the retention flange in a direction
away from the annular rim; and a retention member engaging the
retention flange and the annular rim configured to restrain an
axial displacement of the retention flange away from the annular
rim due to the biasing force of the at least one spring member.
2. The power tool of claim 1, wherein, as a tool accessory is
tightened on the threaded portion of the output spindle, the tool
accessory forces the retention member to move in the direction of
the annular rim.
3. The power tool of claim 1, wherein the retention member engages
a second surface of the annular rim facing away from the at least
one spring member.
4. The power tool of claim 3, wherein an inner surface of the
cylindrical wall of the retention member includes an annular
recess, and wherein the retention member comprises a retaining ring
received within the annular recess of the retention member, the
retaining ring coming into selective contact with the second
surface of the annular rim of the output spindle to limit the
displacement of the retention flange away from the annular rim.
5. The power tool of claim 4, wherein the retention member further
comprises an annular shoulder formed by a radial projection on the
inner surface of the cylindrical wall radially in line with the at
least one spring member, the annular shoulder coming into selective
contact with the first surface of the annular rim of the output
spindle to limit the displacement of the retention flange towards
from the annular rim.
6. The power tool of claim 1, further comprising a motor spindle
rotatably driven directly by the motor, a gear case mounted on the
housing that receives an end of the motor spindle, and a bearing
supported by the gear case, wherein the output spindle is received
from a lower end of the gear case into the bearing into engagement
with the motor spindle.
7. The power tool of claim 6, wherein the motor spindle is at a 90
degree angle relative to the output spindle.
8. The power tool of claim 1, wherein the at least one spring
member comprises one or more Belleville discs.
9. The power tool of claim 1, wherein a diameter of the annular rim
of the output spindle is greater than a diameter of the at least
one spring member, but smaller than a diameter of the cylindrical
wall of the retention flange.
10. The power tool of claim 1, wherein the retention flange
includes a flat wall protruding inwardly from the cylindrical wall
that engages a corresponding flat wall of the annular rim of the
output spindle to rotationally fix the retention flange to the
output spindle.
11. The power tool of claim 1, wherein the cylindrical wall of the
retention flange includes a plurality of openings and the annular
rim of the output spindle includes a plurality of radial
projections configured to be fittingly received into the plurality
of openings to rotationally fix the retention flange to the output
spindle.
12. A power tool comprising: a housing; an electric motor housed
within the housing and rotatably driving a motor spindle; a gear
case mounted on the housing; an output spindle received at least
partially within the gear case, wherein the output spindle defines
a longitudinal axis and includes a first distal end to which a tool
accessory is secured, a second distal configured to engage the
motor spindle, and an annular rim integrally extending radially
from the output spindle between the first distal end and the second
distal end; a bearing having an inner race secured to the output
spindle above the annular rim and an outer race secured to the gear
case; a retention flange including a radially-oriented disc-shaped
portion having a center through-hole through which the output
spindle extends and a cylindrical wall peripherally extending from
the disc-shaped portion around the output spindle, wherein the
disc-shaped portion is located between the first distal end and the
annular rim, and the cylindrical wall extends around the annular
rim; and at least one spring member disposed between the annular
rim and the retention flange to apply a downward biasing force the
retention flange away from the annular rim; and a retention member
engaging the retention flange and the annular rim configured to
restrain a downward movement of the retention flange away relative
to the annular rim along the longitudinal axis due to the biasing
force of the at least one spring member.
13. The power tool of claim 12, wherein the output spindle includes
a threaded portion at the first distal end, and as the tool
accessory is tightened on the threaded portion, the tool accessory
applies an upward force to the retention member in the direction of
the annular rim.
14. The power tool of claim 12, wherein an inner surface of the
cylindrical wall of the retention member includes an annular
recess, and wherein the retention member comprises a retaining ring
received within the annular recess of the retention member, the
retaining ring coming into selective contact with an upper surface
of the annular rim of the output spindle to limit the downward
movement of the retention flange.
15. The power tool of claim 14, wherein the retention member
further comprises an annular shoulder formed by a radial projection
on the inner surface of the cylindrical wall radially in line with
the at least one spring member, the annular shoulder coming into
selective contact with a lower surface of the annular rim of the
output spindle to limit an upward movement of the retention
flange.
16. The power tool of claim 12, wherein the motor spindle is at a
90 degree angle relative to the output spindle.
17. The power tool of claim 12, wherein the at least one spring
member comprises one or more Belleville discs.
18. The power tool of claim 12, wherein a diameter of the annular
rim of the output spindle is greater than a diameter of the at
least one spring member, but smaller than a diameter of the
cylindrical wall of the retention flange.
19. The power tool of claim 12, wherein the retention flange
includes a flat wall protruding inwardly from the cylindrical wall
that engages a corresponding flat wall of the annular rim of the
output spindle to rotationally fix the retention flange to the
output spindle.
20. The power tool of claim 12, wherein the cylindrical wall of the
retention flange includes a plurality of openings and the annular
rim of the output spindle includes a plurality of radial
projections configured to be fittingly received into the plurality
of openings to rotationally fix the retention flange to the output
spindle.
Description
RELATED APPLIATION
[0001] This patent application claims the benefit of U.S.
Provisional Patent Application No. 63/071,416 filed Aug. 28, 2020
titled "POWER TOOL," which is incorporated herein by reference in
its entirety.
FIELD OF THE DISCLOSURE
[0002] This disclosure relates to power tools and in particular to
grinding power tools.
BACKGROUND
[0003] In recent years, braking mechanisms have been introduced to
brake and stop the motor in the event of various fault conditions
(e.g., detection of a pinch), or, in some power tools, upon the
user releasing the tool trigger switch. The problem with many
braking mechanisms in power tool applications such as grinders is
that high inertia of the accessory wheel my cause it to loosen and
come off the output spindle upon rapid deceleration caused by
application of strong and abrupt braking of the motor. This is
particularly frequent where a hubbed grinding wheel is used without
an outer tightening nut, where the high inertia of the wheel upon
rapid deceleration may be greater than the tightening friction
between the wheel and the output spindle. What is needed is a
mechanism that increases the friction between the wheel and the
output spindle to prevent it from coming off when brake is
applied.
SUMMARY
[0004] According to an embodiment of the invention, a power tool is
provided including a housing, an electric motor housed within the
housing, and an output spindle rotatably driven by the electric
motor. The output spindle defines a longitudinal axis and includes
a threaded portion near a distal end thereof and an annular rim
integrally extending radially therefrom at a distance from the
threaded portion. In an embodiment, the power tool further includes
a retention flange with a radially-oriented disc-shaped portion
having a center through-hole through which the output spindle
extends and a cylindrical wall peripherally extending from the
disc-shaped portion around the output spindle. The disc-shaped
portion is located between the distal end and the annular rim, and
the cylindrical wall extends around the annular rim. At least one
spring member is provided engaging a first surface of the annular
rim on one end and the disc-shaped portion on another end to bias
the retention flange in a direction away from the annular rim. A
retention member is provided to engage the retention flange and the
annular rim and is configured to restrain an axial displacement of
the retention flange away from the annular rim due to the biasing
force of the spring member.
[0005] In an embodiment, as a tool accessory is tightened on the
threaded portion of the output spindle, the tool accessory forces
the retention member to move in the direction of the annular
rim.
[0006] In an embodiment, the retention member engages a second
surface of the annular rim facing away from the spring member.
[0007] In an embodiment, an inner surface of the cylindrical wall
of the retention member includes an annular recess. In an
embodiment, the retention member includes a retaining ring received
within the annular recess of the retention member. The retaining
ring comes into selective contact with the second surface of the
annular rim of the output spindle to limit the displacement of the
retention flange away from the annular rim.
[0008] In an embodiment, the retention member further includes an
annular shoulder formed by a radial projection on the inner surface
of the cylindrical wall radially in line with the spring member.
The annular shoulder comes into selective contact with the first
surface of the annular rim of the output spindle to limit the
displacement of the retention flange towards from the annular
rim.
[0009] In an embodiment, the power tool further includes a motor
spindle rotatably driven directly by the motor, a gear case mounted
on the housing that receives an end of the motor spindle, and a
bearing supported by the gear case. The output spindle is received
from a lower end of the gear case into the bearing into engagement
with the motor spindle.
[0010] In an embodiment, the motor spindle is at a 90 degree angle
relative to the output spindle.
[0011] In an embodiment, the spring member includes one or more
Belleville discs.
[0012] In an embodiment, a diameter of the annular rim of the
output spindle is greater than a diameter of the spring member, but
smaller than a diameter of the cylindrical wall of the retention
flange.
[0013] In an embodiment, the retention flange includes a flat wall
protruding inwardly from the cylindrical wall that engages a
corresponding flat wall of the annular rim of the output spindle to
rotationally fix the retention flange to the output spindle.
[0014] In an embodiment, the cylindrical wall of the retention
flange includes openings and the annular rim of the output spindle
includes radial projections configured to be fittingly received
into the openings to rotationally fix the retention flange to the
output spindle.
[0015] According to an embodiment, a power tool is provided
including a housing, an electric motor housed within the housing
and rotatably driving a motor spindle, a gear case mounted on the
housing, and an output spindle received at least partially within
the gear case. The output spindle defines a longitudinal axis and
includes a first distal end to which a tool accessory is secured, a
second distal configured to engage the motor spindle, and an
annular rim integrally extending radially from the output spindle
between the first distal end and the second distal end. A bearing
is provided including an inner race secured to the output spindle
above the annular rim and an outer race secured to the gear case.
The power tool includes a retention flange with a radially-oriented
disc-shaped portion having a center through-hole through which the
output spindle extends and a cylindrical wall peripherally
extending from the disc-shaped portion around the output spindle.
The disc-shaped portion is located between the first distal end and
the annular rim, and the cylindrical wall extends around the
annular rim. At least one spring member is disposed between the
annular rim and the retention flange to apply a downward biasing
force the retention flange away from the annular rim. A retention
member is provided engaging the retention flange and the annular
rim and is configured to restrain a downward movement of the
retention flange away relative to the annular rim along the
longitudinal axis due to the biasing force of the spring
member.
[0016] In an embodiment, the output spindle includes a threaded
portion at the first distal end, and as the tool accessory is
tightened on the threaded portion, the tool accessory applies an
upward force to the retention member in the direction of the
annular rim.
[0017] In an embodiment, an inner surface of the cylindrical wall
of the retention member includes an annular recess, and the
retention member includes a retaining ring received within the
annular recess of the retention member. The retaining ring comes
into selective contact with an upper surface of the annular rim of
the output spindle to limit the downward movement of the retention
flange.
[0018] In an embodiment, the retention member further includes an
annular shoulder formed by a radial projection on the inner surface
of the cylindrical wall radially in line with the spring member.
The annular shoulder coming in selective contact with a lower
surface of the annular rim of the output spindle to limit an upward
movement of the retention flange.
[0019] In an embodiment, the motor spindle is at a 90 degree angle
relative to the output spindle.
[0020] In an embodiment, the spring member comprises one or more
Belleville discs.
[0021] In an embodiment, a diameter of the annular rim of the
output spindle is greater than a diameter of the spring member, but
smaller than a diameter of the cylindrical wall of the retention
flange.
[0022] In an embodiment, the retention flange includes a flat wall
protruding inwardly from the cylindrical wall that engages a
corresponding flat wall of the annular rim of the output spindle to
rotationally fix the retention flange to the output spindle.
[0023] In an embodiment, the cylindrical wall of the retention
flange includes a series of openings and the annular rim of the
output spindle includes a series of radial projections configured
to be fittingly received into the openings to rotationally fix the
retention flange to the output spindle.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The drawings described herein are for illustrative purposes
only of selected embodiments and not all possible implementations,
and they are not intended to limit the scope of the present
disclosure.
[0025] FIG. 1 is a side cross-sectional view of a power tool,
according to an embodiment;
[0026] FIG. 2 is a side cross-sectional view of a conventional
wheel retention mechanism;
[0027] FIG. 3 depicts a perspective cross-sectional view of an
improved wheel retention mechanism, according to an embodiment;
[0028] FIG. 4 depicts a partial side cross-sectional view of the
wheel retention mechanism in an unmounted position, according to an
embodiment;
[0029] FIG. 5 depicts a partial side cross-sectional view of the
wheel retention mechanism in a mounted position, according to an
embodiment;
[0030] FIG. 6 depicts a perspective view of a retention flange,
according to an embodiment;
[0031] FIG. 7 depicts a perspective view of an output spindle,
according to an embodiment;
[0032] FIG. 8 depicts a perspective exploded view of the wheel
retention mechanism, according to an embodiment;
[0033] FIG. 9 depicts a perspective exploded view of an alternative
embodiment of the wheel retention mechanism, according to an
embodiment;
[0034] FIG. 10 depicts a side view of the power tool, according to
an embodiment; and
[0035] FIG. 11 depicts a top cross-sectional view of the power tool
showing the side air intakes and air inlets, according to an
embodiment;
[0036] Corresponding reference numerals indicate corresponding
parts throughout the several figures of the drawings.
DETAILED DESCRIPTION
[0037] The following description illustrates the claimed invention
by way of example and not by way of limitation. The description
clearly enables one skilled in the art to make and use the
disclosure, describes several embodiments, adaptations, variations,
alternatives, and uses of the disclosure, including what is
presently believed to be the best mode of carrying out the claimed
invention. Additionally, it is to be understood that the disclosure
is not limited in its application to the details of construction
and the arrangements of components set forth in the following
description or illustrated in the drawings. The disclosure is
capable of other embodiments and of being practiced or being
carried out in various ways. Also, it is to be understood that the
phraseology and terminology used herein is for the purpose of
description and should not be regarded as limiting.
[0038] FIG. 1 is a side cross-sectional view of a power tool 10,
according to an embodiment. In an embodiment, power tool 10 is
provided including a housing 12 having a gear case 14, a motor case
16, a handle portion 18, and a battery receiver 20. Power tool 10
as shown herein is an angle grinder with the gear case 14 housing a
gearset 22 that drives an output spindle 24 arranged to be coupled
to a grinding or cutting disc (not shown, herein referred to as
"accessory wheel"), either via threads on the disc, or via a flange
(or threaded nut) 26 and guarded by a disc guard (not shown). It
should be understood, however, that the teachings of this
disclosure may apply to any other power tool including, but not
limited to, a saw, drill, sander, and the like. Gearset 22 may
include the output spindle 24 at a 90-degree angle orientation or
in a linear orientation. In an embodiment, gear case 14 includes an
upper gear case cover 14a and a lower gear case cover 14b that
cooperatively house the gearset 22 components.
[0039] In an embodiment, the motor case 16 attaches to a rear end
of the gear case 14 and houses a motor 28 operatively connected to
the gear set 22. An intermediary plate or baffle may be disposed
between the motor case 16 and the rear end of the gear case 14. In
an embodiment, the motor 28 is a brushless direct-current (BLDC)
motor having a stator 30 and a rotor 32 rotatable relative to the
stator 30. The rotor 32 is mounted on a rotor shaft 34 that
rotatably drives the output spindle 24 via the gearset 22. A fan 35
is mounted on the rotor shaft 34 between the motor 28 and the gear
case 14, facing the intermediary plate or baffle, to generate an
airflow for cooing the motor 28 and other components. The airflow
generated by the fan 35 exits through an air exhaust vent 72
provided on the motor case 16 and/or the gear case 14.
[0040] In an embodiment, the handle portion 18 extends from a rear
end of the motor case 16 and includes a trigger switch 36
operatively connected to a switch assembly 38. The switch assembly
38 is in turn coupled to a control module 37 that includes a
programmable controller and controls a switching operation of a
power module 39. In an embodiment, the control module 37 is
disposed at a rear of the handle portion 18 adjacent the battery
receiver 20. The battery receiver 20 is provided at the rear end of
the handle portion 18 for detachable engagement with a battery pack
(not shown) to provide power to the motor 28.
[0041] In an embodiment, a second handle 40 is provided that
extends from the rear end of the motor case 16 to the battery
receiver 20, at least partially in parallel to the handle portion
18. In an embodiment, second handle 40 is a D-handle designed to
enhance structural support for the handle portion 18 and the
battery pack and improve drop performance of the power tool 10. In
an embodiment, second handle 40 is provided with a bumper 42
arranged to absorb shock during drop or impact. In an embodiment,
bumper 42 is made of an overmold material.
[0042] In an exemplary embodiment, the battery pack may be a
60-volt max lithium-ion type battery pack, although battery packs
with other battery chemistries, shapes, voltage levels, etc. may be
used in other embodiments. In various embodiments, the battery
receiver 20 and battery pack may be a sliding pack disclosed in
U.S. Pat. No. 8,573,324, hereby incorporated by reference. However,
any suitable battery receiver and battery back configuration, such
as a tower pack or a convertible 20V/60V battery pack as disclosed
in U.S. patent application Ser. No. 14/715,258 filed May 18, 2015,
also incorporated by reference, can be used. The present embodiment
is disclosed as a cordless, battery-powered tool. However, in
alternate embodiments power tool can be corded, AC-powered tools.
For instance, in place of the battery receiver and battery pack,
the power tool 10 include an AC power cord coupled to a transformer
block to condition and transform the AC power for use by the
components of the power tools. Power tool 10 may for example
include a rectifier circuit adapted to generate a positive current
waveform from the AC power line. An example of such a tool and
circuit may be found in US Patent Publication No. 2015/0111480,
filed Oct. 18, 2013, which is incorporated herein by reference in
its entirety.
[0043] In an embodiment, the power module 39 is disposed at a rear
of the motor 28, i.e. between the motor case 16 and the handle
portion 18. In an embodiment, power module 39 is a circuit board
oriented radially adjacent the end of the motor 28 including a
series of Field-Effect Transistors (FETs) interconnected as a
multi-phase inverter circuit for powering the phases of the motor
28. In an embodiment, control module 37, switch assembly 38, and
power module 39 may be provided discretely or integrated into
sub-assemblies.
[0044] In an embodiment, the control module 37 uses the input from
the trigger assembly 38 to set a target speed for the motor 28.
This is done by controlling a pulse-width modulation (PWM) of the
power switches within the power module 39. When the trigger switch
36 is released, in an embodiment, the control module 37 activates
the low-side switches or the high-side switches of the power module
39 simultaneously for regenerative electronic braking of the motor
28. A description of the power and control modules and electronic
braking of the motor can be found in US Patent Publication No.
2017/0234484, filed Feb. 10, 2017, which is incorporated herein by
reference in its entirety.
[0045] Braking of the motor at high speed, either electronically or
via a mechanical brake, causes rapid deceleration of the output
spindle 24. Absent a mechanism to retain and protect the accessory
wheel, high inertia of the accessory wheel can cause it to detach
from the output spindle 24 upon rapid deceleration. For this
reason, in some configurations, the nut 26 may be provided with a
spring mechanism to apply an upward force on the accessory wheel to
increase friction between the accessory disc and an upper flange of
the power tool 10. Additionally, and/or alternatively, in some
configurations, the power tool 10 may be provided with a wheel
retention mechanism configured to apply a downward force on the
accessory wheel to similarly increase the friction between the
accessory disc and the upper flange of the power tool 10 as well as
the friction between the threads of the accessory wheel and the
output spindle 24, resulting in an increased accessory unseating
torque. This increased friction significantly reduces the
likelihood of the accessory wheel coming off the output spindle
24.
[0046] Referring to FIG. 2, a prior art wheel retention mechanism
100 is described. Only the lower gear case cover 114b, output
spindle 124, and wheel retention mechanism 100 components are
illustrated in this view. In this configuration, output spindle 124
is axially fixed to the lower gear case cover 114b via a bearing
122 and includes a rim 126 disposed at a location below the bearing
122 and below a plane of the lower gear case cover 114b. Wheel
retention mechanism 100 includes a transfer member 128 disposed
around the output spindle 124 above the rim 126. A spring member
130 (in this example a Belleville disc) is disposed between the
transfer member 128 and the bearing 122 (via a spacer 132). A
backing flange (not shown) is typically mounted on the lower end of
the output spindle 124 in contact with the transfer member 128.
When a wheel accessory is mounted on the output spindle 124, the
rotational force of the accessory as it is being tightened imparts
an upward force on the transfer member 128 through the backing
flange, causing the transfer member 128 to move upward relative to
the output spindle 124 against the force of the spring member 130.
The spring member 130 applies a downward force on the transfer
member 128, thus increasing friction between the transfer member
128, the backing flange, and the wheel accessory.
[0047] In this configuration, during manufacturing and assembly,
the transfer member 128 and spring member 130 are mounted over the
rim 126 before the output spindle 124 is received through the
bottom surface of the lower gear case cover 114b. The bearing 122
is then mounted on the output spindle 124 (e.g., by press-fitting
or slip-fitting) with the spring member 130 in a preload condition.
This process has been found to be slow and burdensome. In addition,
since the force of the spring 130 is transferred to the bearing 122
during use, it has been found to adversely affect the press between
the bearing 122 and the output spindle 124 and at times even cause
displacement of the bearing 122 over time.
[0048] U.S. Pat. No. 9,399,278 is another example of a prior art
wheel retention mechanism. In this configuration, a flange is
mounted on the output spindle (either via threads or press-fitting)
to support one end of the spring element. Thus, the force of the
spring element is not transferred to the bearing. However, the
transfer element is not self-supported on the output spindle and
can only be mounted via a supporting flange.
[0049] The embodiment of the invention described herein overcomes
the problems associated with the prior art configuration of FIG. 2,
but also provides a wheel retention mechanism that is
self-supported on the output spindle.
[0050] Referring to FIG. 3, wheel retention mechanism 200 includes
a retention flange 202 and one or more spring elements 204. In an
embodiment, retention flange 202 has a cup-shaped body that
includes a main disc-shaped portion 220 having a center
through-hole disposed around the output spindle 24 and a
cylindrical wall 222 extending peripherally from the disc-shaped
portion 220. Output spindle 24 includes an annular rim 210 below
which the spring elements 204 and disc-shaped portion 220 of the
retention flange 202 are disposed. Spring elements 204 are
sandwiched between the annular rim 210 and the disc-shaped portion
220 of the retention flange 202. The spring members 204 are
depicted in this example as a stack of Belleville discs, though it
should be understood that a single Belleville disc, or an
alternative form of spring such as a compression spring, may
alternatively be utilized. A top portion of the cylindrical wall
222 of the retention flange 202 includes an annular recess 224 in
its inner surface that receives a retaining ring 206. Retaining
ring 206 sits above the annular rim 210 to axially limit the
downward movement of the retention flange 202.
[0051] In an embodiment, annular rim 210 is provided at
approximately the same plane as a bottom portion of the lower gear
case cover 14b with a diameter that is greater than a diameter of
the spring elements 204 and at least twice the diameter of the
output spindle 24. A bearing 212 is provided above the annular rim
210 to axially secure the output spindle 24 to the lower gear case
cover 14b. Gearset 22 is provided above the bearing 212 to
rotationally drive the output spindle 24. A threaded portion 214 of
the output spindle 24, to which a threaded wheel accessory or a
threaded nut is fastened, is positioned below the lower surface of
the retention flange 202.
[0052] FIG. 4 depicts a partial side cross-sectional view of the
wheel retention mechanism in an unmounted position of the wheel
accessory (i.e., where no accessory wheel is tightened on the
threated portion 214 of the output spindle 24), according to an
embodiment. In an embodiment, in the unmounted position, the spring
members 204 exert a force in the direction B to the retention
flange 202. The force of the spring members 204 in the direction B
causes the disc-shaped portion 220 of the retention flange 202 to
move away from the annular rim 210 of the output spindle 24,
creating a small separation between the annular rim 210 and an
annular shoulder 226 of the retention flange 202. This movement is
limited by the retaining ring 206 as it meets a top portion of the
annular rim 210.
[0053] FIG. 5 depicts a partial side cross-sectional view of the
wheel retention mechanism in a mounted position of the wheel
accessory, according to an embodiment. In an embodiment, in the
mounted position, after the accessory wheel (or an intermediary
flange or spacer) comes into contact with the retention flange 202,
the continued fastening of the accessory wheel or the nut on the
threaded portion 214 of the output spindle 24 applies a force in
the direction A to the retention flange 202. Once this force is
greater than the force of the spring members 204 in direction B,
the retention flange 202 is moved towards the annular rim 210 until
the annular shoulder 226 of the retention flange 202 comes into
contact with the annular rim 210. This causes a small separation
between the upper portion of the annular rim 210 and the retaining
ring 206. In this position, the spring members 204 continues to
apply a downward force on the retention flange 202, which increases
the traction between the accessory wheel and the retention flange
202 and improve the retention of the accessory wheel on the output
spindle 24.
[0054] FIG. 6 depicts a perspective view of the retention flange
202, according to an embodiment. FIG. 7 depicts a perspective view
of the output spindle 24, according to an embodiment. As shown in
these figures, retention flange 202 includes one or more flat walls
228 (in this example, two flat walls 228) provided on the inner
surface of the cylindrical wall 222. The annular rim 210 of the
output spindle 24 similarly includes one or more flat side portions
230 (in this example, two flat walls 228) arranged to engage the
flat walls 228 of the retention flange 202. This ensures that the
retention flange 202 is rotationally coupled to the output spindle
24.
[0055] FIG. 8 depicts a perspective exploded view of the wheel
retention mechanism 200 described above, according to an
embodiment. As seen here, and with continued reference to FIG. 3, a
sub-assembly including the wheel retention mechanism 200 and the
output spindle 24 may be assembled independently from the gear case
14. In an embodiment, to provide this sub-assembly, the retention
flange 202 and the spring elements 204 are mounted on the annular
rim 210 of the output spindle 24 and secured via the retaining ring
206. To mount the sub-assembly on the gear case 14, the output
spindle 24 of the sub-assembly is received through a lower surface
of the lower gear case cover 14b into the bearing 212. In an
embodiment, gearset 22 is also press-fitted onto the output spindle
24.
[0056] FIG. 9 depicts a perspective exploded view of a wheel
retention mechanism 300, according to an alternative embodiment of
the invention. In this embodiment, to the extent that the wheel
retention mechanism 300 includes many of the same features
described above, the same numeric references are provided. In an
embodiment, output spindle 24 is provided with a modified annular
rim 310 having a series of (in this example, four) radial
projections 312 forming a series of recesses 314 therebetween. In
an embodiment, a modified retention flange 302 is also provided
including a cylindrical wall 322 that includes a series of (in this
example, four) openings 324. The openings 324 are configured to
receive the radial projections 312 of the annular rim 310, allowing
the cylindrical wall 322 to be rotationally locked to annular rim
310. In an embodiment, spring elements 204 are sandwiched between
the disc-shaped portion 320 of the retention flange 302 and the
annular rim 310 of the output spindle 24. In an embodiment,
retaining ring 206 is received within an annular recess 326 of the
cylindrical wall 322 and sits above the annular rim 310 to limit
the axial displacement of the retention flange 302 relative to the
output spindle 24.
[0057] Both embodiments of the retention flange described above
provide for a self-supporting wheel retention mechanism that can be
manufactured and mounted on the output spindle as a sub-assembly
prior to assembly of the output spindle into the gear case.
Further, the spring force of the retention flange is transferred to
the annular rim of the output spindle rather than the bearing, thus
reducing wear and damage to the bearing over time.
[0058] Another aspect of the invention is described herein with
reference to FIGS. 10 and 11.
[0059] FIG. 10 depicts a side view of the power tool 10 showing a
left-side air intake 50, according to an embodiment. FIG. 11
depicts a top cross-sectional view of the power tool 10 along plane
A shown in FIG. 10, according to an embodiment.
[0060] In an embodiment, the fan 35 rotates with the motor shaft 32
to generate an airflow through the motor 28 and other power tool
components. The power tool housing 12 is provided with two side air
intakes 50 and 60 positioned in the motor case 16 around the motor
28 for entry of ambient air. Air intake 50 and 60 are provided with
screens (or a filters) 52 and 62 that blocks entry of dust and
particulate through the air intakes 50 and 60. The filtered air
then enters into the motor casing 16 through two air inlets 54 and
64 positioned radially inwardly of the air intakes 50 and 60. While
screens 52 and 62 filter out majority of the debris and
particulate, small amounts of debris can still get in through the
screens 52 and 62. The filtered air travels along the outer sides
of the motor 28 in a direction opposite the direction of the gear
case 14, enters into the motor 28 through a series of openings 70
at the end of the motor 28, and travels through the stator 30
and/or the rotor 32 to cool the motor 28 components. The air then
enters the gear case 24 or exists via the air exhaust vent 72
provided close to the gear case 24.
[0061] In an embodiment, wheel accessory (not shown) is rotates in
a clockwise direction (direction E in FIG. 11) when viewing the
power tool 10 from the top. This causes a higher concentration of
grinding or cutting debris and particulate in the ambient air on
the right side of the tool 10 than the left side when viewed from
the top. According to an embodiment of the invention, to reduce
exposure to the contaminated air and provide cleaner airflow in the
power tool, right-side air inlet 64 is configured to be smaller
than the left-side air inlet 54. In an embodiment, a width or
diameter D of the right-side air inlet 64 is smaller than a width
or diameter C of the left-side air inlet 54. In an embodiment, the
width or diameter D of the right-side air inlet 64 is 80% to 90% of
the width or diameter C of the left-side air inlet 54. The smaller
right-side air inlet 64 allows a lower proportion of incoming air
from the right side of the power tool 10 than the left side, thus
reducing the total amount of contamination entering the motor
28.
[0062] In an embodiment, an area of the right-side air inlet 64 is
in the range of 300 to 600 mm.sup.2, preferably in the range of 400
to 500 mm.sup.2, and an area of the left-side air inlet 54 is in
the range of 500 to 800 mm.sup.2, preferably in the range of 600 to
700 mm.sup.2. In an embodiment, the area of the right-side air
inlet 64 is approximately 60% to 90%, preferably 70% to 80%,
preferably approximately 73% to 77%, of the area of the left-side
air inlet 54.
[0063] This configuration provides for airflow through the
right-side air inlet 64 in the range of approximately 10 to 16 cfm
(cubic-feet per minute), preferably in the range of 12 to 14 cfm,
and airflow through the left-side air inlet 54 in the range of
15-21 cfm, preferably in the range of 17-19 cfm. In an embodiment,
the airflow through the right-side air inlet 64 is approximately
60% to 90%, preferably 65% to 80%, more preferably 70% to 75%, of
the airflow through the left-side air inlet 54.
[0064] It should be understood that while in this example, the air
inlets 54 and 64 are provided with different sizes, other
components on the path of the airflow (e.g., the air intakes 50 and
60, the screens 52 and 62, the left and right air channels along
the sides of the motor 28, etc.) may be similarly or alternatively
provided with different sizes or shapes to provide a smaller
airflow from the right-side air intakes 60 than the left-side air
intakes 50. Similarly, the shape, thickness, or meshing of the
screens 52 and 62 may be different to allow more airflow through
the left-side screen 52 than the right-side screen 62.
[0065] 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.
[0066] Example embodiments are provided so that this disclosure
will be thorough, and will fully convey the scope to those who are
skilled in the art. Numerous specific details are set forth such as
examples of specific components, devices, and methods, to provide a
thorough understanding of embodiments of the present disclosure. It
will be apparent to those skilled in the art that specific details
need not be employed, that example embodiments may be embodied in
many different forms and that neither should be construed to limit
the scope of the disclosure. In some example embodiments,
well-known processes, well-known device structures, and well-known
technologies are not described in detail.
[0067] The terminology used herein is for the purpose of describing
particular example embodiments only and is not intended to be
limiting. As used herein, the singular forms "a," "an," and "the"
may be intended to include the plural forms as well, unless the
context clearly indicates otherwise. The terms "comprises,"
"comprising," "including," and "having," are inclusive and
therefore specify the presence of stated features, integers, steps,
operations, elements, and/or components, but do not preclude the
presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. The
method steps, processes, and operations described herein are not to
be construed as necessarily requiring their performance in the
particular order discussed or illustrated, unless specifically
identified as an order of performance. It is also to be understood
that additional or alternative steps may be employed.
* * * * *