Note: Descriptions are shown in the official language in which they were submitted.
CA 02348985 2001-05-28
GEAR AND LEVER SPINDLE LOCK
Background and Summary of the Invention
The present invention relates to power tools and, more particularly, to power
tools having a device for locking the spindle against rotation.
In rotary tools that are used by hobbyists, several different types of bits
are
used in the rotary tool. Ordinarily, a collet is present which receives the
tool bit. The
collet is tightened to retain the tool bit within the collet on the tool.
Ordinarily, these
collets are tightened by the rotation of a collet nut to provide the
frictional force
necessary to retain the tool bit within the collet. In order to loosen or
tighten the collet
nut to release a tool bit or secure a tool bit, respectively, the collet nut
must be rotated.
In order to rotate the collet nut with respect to the tool motor, it is
desirable to inhibit
rotation of the motor shaft of the tool so that the collet nut may be rotated.
One type
of device utilized to accomplish this task is a push button mechanism which,
in turn,
prohibits rotation of the motor shaft. While this device works satisfactorily
for its
intended purpose, designers are always striving to improve the art.
The present invention provides the art with a rotatable member which, when
it is rotated into a lock position, prohibits rotation of the output spindle.
The member
may be rotated to its locked position and released, enabling the user to
easily access
the collet nut. The rotatable member includes a mechanism to receive the
on/off
switch, as well as to prohibit activation of the on/off switch while it is in
its locked
position. Further, a device is provided to positively set the rotating member
in a locked
and unlocked position.
In accordance with a first aspect of the invention, a shaft locking mechanism
for a power tool comprises a member adapted to be rotatable about a pivot. The
member has a first projection to rotate the member about the pivot. The member
has
CA 02348985 2001-05-28
a second projection to engage a gear. A gear is adapted to be secured on a
shaft of
the power tool. The first projection rotates the member between an engaged
position,
where the second projection engages the gear prohibiting rotation of the
output
spindle, to a disengaged position, where the second projection disengages from
the
gear, enabling rotation of the output spindle. The member also includes a
receiving
portion to receive an on/off switch of the power tool. The member includes at
least
one detent associated with a spring member to hold the member in the engaged
or
disengaged position. The spring member positively sets the member in the
engaged
and disengaged position. A pair of detents, one for the engaged position and
one for
the disengaged position, are formed in the member. In a first position, the
first
projection is parallel with respect to a central axis of the tool where the
member is in
a disengaged position. In a second position, the first projection is
perpendicular to the
central axis and the second projection engages the gear. The member has an
annular
body with an interior aperture to receive the pivot. The on/off switch is
disabled when
the first projection is in the perpendicular position. The receiving portion
includes a
cantilevered member defining a cut-out to receive the on/off switch.
In accordance with a second embodiment of the invention, a power tool
comprises a housing with a motor within the housing. The motor is coupled with
an
output shaft and is also coupled with a power source. An on/off switch on the
housing
is coupled with the power source and the motor to energize and de-energize the
motor. When the motor is energized, the motor rotates the output shaft. A
member
is coupled with the housing to prohibit rotation of the output shaft. The
member has
a first projection for rotating the member about a pivot on the housing. The
member
has a second projection to engage a gear on the output shaft. A gear is
adapted to
be secured on the output shaft. The first projection rotates the member
between an
engaged position, where the second projection engages the gear prohibiting
rotation
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of the output shaft, to a disengaged position, where the second projection
disengages
from the gear, enabling rotation of the output shaft. The member also includes
a
receiving portion to receive the on/off switch of the power tool. The member
includes
at least one detent associated with a spring member to hold the member in the
engaged or disengaged position. The spring member positively sets the member
in
the engaged and disengaged position. A pair of detents, one for the engaged
position
and one for the disengaged position, are formed in the member. In a first
position, the
first projection is parallel with respect to a central axis of the tool where
the member
is in a disengaged position. In a second position, the first projection is
perpendicular
to the central axis and the second projection engages the gear. The member has
an
annular body with an interior aperture to receive the pivot. The on/off switch
is
disabled when the first projection is in the perpendicular position. The
receiving
portion includes a cantilevered member defining a cut-out to receive the
on/off switch.
Additional objects and advantages of the present invention will become
apparent from the detailed description of the preferred embodiment, and the
appended claims and accompanying drawings, or may be learned by practice of
the
invention.
Brief Description of the Drawings
Figure 1 illustrates a perspective view of a rotary tool in accordance with
the
present invention.
Figure 2 illustrates a partial cross-section view of the rotary tool according
to
Figure 1.
Figure 3 is a view like that of Figure 2 with the rotary member in a second
position.
Figure 4 is a perspective view of the shaft locking mechanism of Figure 3.
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Figure 5 is a partial cross-section view like Figure 3 of an additional
embodiment of the present invention.
Figure 6 is a perspective view like Figure 4 of the embodiment of Figure 5.
Detailed Description of the Preferred Embodiment
Turning to Figures 1 and 2, a rotary tool is illustrated and designated with
the
reference numeral 10. The rotary tool 10 includes a housing 12 which houses a
motor
14. The motor 14 is coupled with an output shaft 16. The output shaft 16 has a
collet
18 on its end to receive rotary tool bits. A power source, in this view a cord
20, is
coupled with the motor 14 to energize the motor. An on/off switch 22 is
electrically
coupled with the motor 14 and the power cord 20 to energize the motor 14. The
on/off
switch 22 includes a sliding member 24 which activates a push button switch 26
which
is electrically coupled with the motor 14 and power source 20. A shaft locking
member 30 is coupled with the housing 12.
Turning to Figures 2-4, a better understanding of the rotary member 30 can be
found. The rotary member 30 has an annular body 32 with an aperture 34 which
is
received on a pivot pin 36 of the housing 12. The rotary member 30 includes a
first
projecting member 38. The projecting member 38 enables the user to grab it and
rotate the rotary member 30 about the pivot 36. The annular body 32 includes a
second projecting member 40 which has an overall tooth shape. A third
projecting
portion 42 includes a cantilevered portion 44 which defines a cut-out 46 which
receives a portion of the sliding onloff switch 24. As can be seen in Figure
2, when
the first projection 38 is substantially parallel with the axis of the tool,
the on/off switch
24 can be slid into the cut-out 46 to energize the power tool. After use, the
on/off
switch 24 is slid out of the cut-out 46. When the on/off switch 24 is in the
cut-out 46,
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the rotating member 30 cannot be rotated and is locked in position when the
power
tool is energized.
The annular body 32 includes a pair of detents 50 and 52. The detents 50 and
52 receive the head 54 of a spring member 56 which positively holds the rotary
member 30 in its engaged and disengaged positions. The head 54 is ordinarily a
cap
which is connected to a spring 56. The spring 56 and cap 54 are seated in a
channel
58 in the housing 12. Thus, as the member 30 is rotated, the cap moves inward
into
the channel 58 against the bias of the spring 56. The cap 54 cams along the
body
surface 32 until the spring 56 biases the cap 54 into the second detent 52. In
the
second detent 52, the rotary member 30 is held in its second or engaged
position.
A gear 60 is secured onto the output shaft 16. The gear 60 includes a
plurality
of teeth 62 positioned about its annular body. The gear 60 is fixed onto the
output
shaft 16 so that when the tooth projection 40 engages the gear 60 as
illustrated in
Figure 3, the output shaft 16 is prohibited from rotating. Thus, in order to
prohibit
rotation of the output shaft 16, the projecting member 38 is rotated until it
is
substantially perpendicular to the axis of the tool. In this position, the
tooth projection
40 meshes between a pair of teeth 62 on gear 60. Thus, the output shaft 16 is
prohibited from rotating. Likewise, when the tooth 40 engages the gear 60, the
cap
54 of the spring mechanism 56 engages detent 52 as illustrated in Figure 3.
Thus, the
rotating member 30 is held in position by the spring mechanism frictionally
biasing in
the detent 52.
As illustrated in Figure 3, the sliding switch 24 cannot be moved forward to
energize the motor. Thus, the power tool is locked in an off position when the
rotary
member 30 engages the gear 60. The projecting member 38 may include a rubber
boot 64 to enhance the feel for the user to move it between the engaged and
disengaged position.
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To disengage the tooth projection 40, the first projection 38 is rotated
clockwise
until it is substantially parallel with the central axis of the power tool. At
this time, the
on/off switch 24 can be slid forward to be received within the cut-out 46.
The tool may be removed from the collet 18 when the output shaft 16 is
prohibited from rotating as illustrated in Figure 3. In order to remove the
tool, the tooth
projection engages the gear teeth 62 which, in turn, enables the collet nut 64
to be
rotated. As the collet nut 64 is rotated; it releases the grasping force on
the collet
fingers 66 of the collet 68. Thus, as the collet fingers 66 expand, the tool
may be
removed. To retain the tool, the collet nut 64 is tightened which, in tum,
exerts a
grasping force on the collet fingers 66 to retain the tool in the collet 68.
Turning to Figures 5 and 6, an additional embodiment of the present invention
is shown. The embodiment of Figures 5 and 6 are similar to that of Figures 3
and 4
with the same elements having the same identification numerals. The difference
between the figures is the gear 60'. Here, the gear 60' includes teeth 62'
which
include an angled surface 72'. The angled surfaces act as cam surfaces to
engage
the tooth 40 of the rotary member 30. Also, the gear 60' includes one tooth
74' which
has an angled surface 76'. When viewed in elevation, tooth 74' is axially
longer on the
gear 60' than the other teeth 62' as seen in Figure 5. Thus, the tooth 74',
with its
angled surface 76', would be the first tooth to contact the tooth 40 of the
rotary
member 30 as the tooth 40 attempts to mesh with gear 60' during rotation of
the shaft
16 as the shaft 16 winds down.
As the power is terminated to the power tool, the spindle 16 continues to
rotate.
As the spindle continues to rotate, the gear 60' continues to rotate. If the
rotary
member 30 attempts to be engaged during this rotation, the tooth 40 contacts
the
teeth 62' and 74'. Since the tooth 74' is longer than the other teeth 62', the
tooth 74'
contacts the tooth 40 at a regular duration as the gear and spindle continue
to rotate
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and slow down. The long tooth 74' contacts the tooth 40 of the rotary member
30 with
a strong force, giving a positive feedback to the user that the lever cannot
be engaged.
The single long tooth enables one tooth to contact the tooth 40 of the rotary
member
30 during a single rotation instead of each tooth 62' contacting the tooth 40.
The
contacting of each tooth would produce a rapid contacting of the tooth 40 and
not a
solid impact which occurs by the single tooth 74'. Thus, the strong kickout
force
indicates to the user that the spindle lock is not ready to be engaged since
the spindle
has not stopped its rotation.
While the above detailed description describes the preferred embodiment of
the present invention, the invention is susceptible to modification,
variation, and
alteration without deviating from the scope and fair meaning of the subjoined
claims.
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