U.S. patent application number 09/852476 was filed with the patent office on 2001-10-11 for combination string and blade trimmer with auxiliary blower function.
Invention is credited to Dyke, Colin, Lessig, William R. III, Meloni, Robert A., Waldrop, Angela Marie, Wheeler, Dale Kenneth.
Application Number | 20010027610 09/852476 |
Document ID | / |
Family ID | 22124880 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010027610 |
Kind Code |
A1 |
Wheeler, Dale Kenneth ; et
al. |
October 11, 2001 |
Combination string and blade trimmer with auxiliary blower
function
Abstract
A trimming tool includes a selectable blade attachment for
effecting a conversion between a string trimming mode and a blade
trimming mode without requiring disassembly of the unit. The
assembly includes a locking mechanism (46) selectively engageable
with a pivoting trimming blade (40) that pivots between a retracted
position and an extended position by centrifugal force. In one
embodiment, the locking mechanism is reciprocated between the
locked position and the unlocked position based on a rotation
direction of the motor. The locking mechanism itself may also be
reciprocated by centrifugal force. A spool lock, which is also
positioned by centrifugal force, disables automatic string feeding
in the blade trimming mode. The trimming tool may also be provided
with a blower function incorporating a blower attachment readily
attachable as a trimming guard of the trimming tool, or a blower
assembly integrated into the tool components.
Inventors: |
Wheeler, Dale Kenneth;
(Fallston, MD) ; Waldrop, Angela Marie;
(Parkville, MD) ; Dyke, Colin; (North Augusta,
CA) ; Lessig, William R. III; (Monkton, MD) ;
Meloni, Robert A.; (Baltimore, MD) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, PLC
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
22124880 |
Appl. No.: |
09/852476 |
Filed: |
May 10, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09852476 |
May 10, 2001 |
|
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09622729 |
Nov 7, 2000 |
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60075311 |
Feb 20, 1998 |
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Current U.S.
Class: |
30/276 ;
30/347 |
Current CPC
Class: |
A01D 34/416 20130101;
A01D 34/736 20130101 |
Class at
Publication: |
30/276 ;
30/347 |
International
Class: |
A01D 034/42 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 19, 1999 |
US |
PCTUS9903696 |
Claims
What is claimed is:
1. A device for trimming vegetation, the device comprising: a
housing; a motor disposed within the housing; a cutting element
(22) driven by the motor; and an air stream generating element
supported on the housing.
2. The device of claim 1, wherein the air stream generating element
is operable while the cutting element (22) is driven to cut
vegetation.
3. The device of claim 1, wherein the air stream generating element
is operable while the cutting element (22) is at rest.
4. The device of claim 1, wherein the air stream generating element
is permanently attached to the housing.
5. The device of claim 1, further comprising a system for directing
said air stream (112) permanently attached to the housing.
6. The device of claim 1, wherein the air stream generating system
comprises a fan.
7. The device of claim 1, wherein the system for directing the air
stream comprises a conduit (112).
8. The device of claim 7, wherein the conduit comprises a scroll
(112).
9. A device for trimming vegetation, the device comprising: a
housing; a motor; a cutting element (22) driven by the motor; and a
support member designed to receive the cutting element; and a
blower attached to the housing independent of the cutting element
and the support member, for providing an airflow over said
motor.
10. The device of claim 9, wherein the blower comprises a fan.
11. The device of claim 10, wherein the blower further comprises a
scroll (112) to direct airflow generated by the fan.
12. The device of claim 9, wherein the blower is operable to
generate airflow while the cutting element (22) is driven to cut
vegetation.
13. The device of claim 9, wherein the blower is operable to
generate airflow while the cutting element (22) is at rest.
14. The device of claim 9, wherein the blower is permanently
attached to the housing.
15. A device for trimming vegetation, the device comprising: a
housing; a motor disposed within the housing; an output shaft
attached to and driven by the motor; a cutting spool (22) secured
to the output shaft; and a fan positioned within the housing to
generate an air stream; and a conduit (112) located adjacent the
cutting spool for directing the air stream generated by the
fan.
16. The device of claim 15, wherein the fan generates an air stream
while the cutting spool (22) is driven to cut vegetation.
17. The device of claim 15, wherein the fan generates an air stream
while the cutting spool (22) is at rest.
18. The device of claim 15, wherein the fan is permanently attached
to the housing.
19. The device of claim 15, wherein the conduit (112) is
permanently attached to the housing.
20. The device of claim 15, wherein the cutting spool (22) includes
string to cut vegetation.
21. The device of claim 15, wherein the cutting spool (22) includes
a plurality of blades to cut vegetation.
22. The device of claim 15, wherein the conduit (112) is
concentrically disposed around the cutting spool (22).
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a trimming tool and, more
particularly, to a combination string and blade trimmer including
an auxiliary blower function.
TECHNICAL FIELD
[0002] A trimming tool is typically used for cutting vegetation
such as grass and the like using one or more strings secured to a
string spool assembly that is rapidly rotatably driven by a motor.
U.S. Pat. No. 5,063,673 describes one type of string spool housing
that incorporates an automatic string feed mechanism that utilizes
centrifugal force to sense a string breakage. GB2 000 672 describes
a grass cutting attachment for a rotary machine such as an
electrically operated drill. A blade trimmer operates on the same
principle as a string trimmer, but uses one or more blades in place
of the string. DE 25 56 553 discloses a cutter head that includes
blades. Blades normally do a better cutting job than string, but
blades cannot be used against a curb or hard surface.
[0003] It is thus desirable to provide a trimming tool that can be
selectively used in a string trimming mode and a blade trimming
mode. Previously, in order to convert a string trimming tool to a
blade trimming tool, the trimmer head had to be disassembled and
reassembled to replace the string spool housing with a blade unit.
By the nature of the tool, the disassembly of the trimmer head is
inherently a dirty task that most consumers would only perform once
and would not bother to repeat.
[0004] In addition, clippings resulting from the cutting operation
must be raked and collected to improve the overall appearance of
the grounds maintenance. U.S. Pat. No. 4,227,280 describes a
vacuum/blower attachment that can be mounted to a conventional
filament line trimmer. U.S. Pat. No. 4,187,577 describes an
attachment device for converting a line trimmer to a blower. U.S.
Pat. Nos. 4,835,950 and 4,827,702 show a fan blade attachment that
may be attached to the outer periphery of the filament line spool
of a filament line trimmer. It would thus also be desirable to
incorporate a blower function with the trimming tool to facilitate
collection and removal of clippings from the cutting operation.
SUMMARY OF THE INVENTION
[0005] The combination string and blade trimming tool according to
the present invention enables a quick conversion between a string
trimming mode and a blade trimming mode without requiring the user
to disassemble and replace a trimmer head. Moreover, a preferred
embodiment of the invention also contemplates an auxiliary blower
that utilizes airflow generated by operation of the motor to be
fluted to an exit opening to effect a blower function.
Alternatively, a fan could be provided separately from the motor
for increased efficiency.
[0006] According to the present invention, a selectable blade
assembly attachment is attachable to an existing or slightly
modified string trimmer assembly. In one embodiment, one or more
trimming blades are pivotally attached to a disc or the like, which
in turn engages a string spool housing of the trimmer. The one or
more trimming blades are biased toward a retracted position by a
spring and are locked in the retracted position by a locking
mechanism in a string trimming mode. To convert from the string
trimming mode to the blade trimming mode, the motor direction is
reversed, releasing the locking mechanism, and the one or more
trimming blades are pivoted to an extended position against the
force of the spring by centrifugal force. The locking mechanism may
be an inertial lock that is activated by centrifugal force. In
order to convert back to the string trimming mode, when the motor
is stopped, the one or more trimming blades are pivoted toward the
retracted position by the spring, and the locking mechanism is
engaged when the motor rotates in the string trimming mode
direction. With this structure, an operator can readily switch
between a string trimming mode and a blade trimming mode without
requiring disassembly of the trimming head.
[0007] In an alternative arrangement of the invention, the combined
functionality can be achieved without requiring reversing of the
motor. In this arrangement, a mechanical actuator positioned near
the handle of the tool is attached to a rotatable cam plate or the
like. When the operator rotates the cam plate, cam surfaces on the
cam plate shift a latch pin from a lowered position to a raised
position, which in turn displaces a latch from a locking position
to a releasing position. In the releasing position, the trimming
blade is free to pivot outward by centrifugal force against the
force of the spring. When the motor is stopped, if the operator
desires to return the tool to the string trimming mode, the
trimming blade is returned toward its retracted position by the
spring and can be resecured with the latch by again rotating or
pulsing the cam plate with the mechanical actuator. Thus, with this
structure, the selectable trimming modes can be realized also
without requiring disassembly of the trimming head and additionally
without requiring an implementation of a reversible motor.
[0008] A permanent auxiliary blower capability can be incorporated
into the trimming tool according to the invention. In this context,
the fan may be separated from or part of the string spool, and a
blower scroll is inserted around the fan and under the spool. The
scroll is screwed or otherwise secured to the underside of the tool
guard. The blower preferably functions continuously with motor
cooling air being directed by the blower scroll. Alternatively, an
optional air exit cover may be connected by cable or the like to a
handle trim/blow selector switch, and in the trim mode, essentially
motor cooling air blows into the string or blade plane to act as an
air boost; in the blow mode, the cover is full open for mass
directed air forward. With the blower functionality, the trimming
tool according to the invention incorporates diverse applications
and facilitates collection and removal of clippings from the
trimming operation.
[0009] In accordance with a particular aspect of the present
invention, there is provided a selectable blade attachment for
string trimming tool including a motor rotatably driving a string
spool housing. The selectable blade attachment includes a trimming
blade assembly engaging the string spool housing and having at
least one trimming blade. The trimming blade is pivotable between a
retracted position and an extended position by centrifugal force.
The blade attachment preferably further includes a locking
mechanism selectively engageable with the trimming blade, wherein
in a locked position, the locking mechanism locks the trimming
blade in the retracted position. The locking mechanism is
preferably structured such that it is reciprocated between the
locked position and an unlocked position by centrifugal force. In
one arrangement of the invention, the locking mechanism is
reciprocated between the locked position and the unlocked position
based on a rotation direction of the motor. In preferred forms, the
trimming blade is biased toward the retracted position by a
spring.
[0010] Additionally, the attachment preferably includes a spool
lock engageable with the string spool housing in a locking position
to prevent automatic string feeding in the blade trimming mode,
wherein the spool lock is shifted between a releasing position and
the locking position by centrifugal force.
[0011] Other features of the invention utilize a locking bar and
blade lock plate in the locking mechanism. Structure supporting the
blade and locking mechanism may include chamfered edges to decrease
wind resistance during operation. In yet another arrangement of the
invention, the locking mechanism is engaged and disengaged with an
actuator, such as a pull cable.
[0012] In accordance with another aspect of the invention, there is
provided a trimming tool including a motor having an output shaft,
a string spool housing attached to the output shaft for rotation by
the motor, wherein the string spool housing spools a cutting string
for the tool, and a trimming blade assembly engaging the string
spool housing including at least one trimming blade, wherein the
trimming blade is pivotable between a retracted position and an
extended position by centrifugal force.
[0013] In yet another aspect of the invention, there is provided a
method of operating a trimming tool in a string trimming mode and a
blade trimming mode. The method includes providing a motor having
an output shaft, providing a string spool housing attached to the
output shaft for rotation by the motor, with the string spool
housing spooling a cutting string for the tool, and providing a
trimming blade assembly engaging the string spool housing and
including at least one trimming blade, with the trimming blade
being pivotable between a retracted position and an extended
position by centrifugal force. In the string trimming mode, the
method includes locking the trimming blade in the retracted
position, and rotating the motor with the trimming blade in the
retracted position. In the blade trimming mode, the method includes
releasing the trimming blade, and rotating the motor so that the
trimming blade is pivoted to the extended position by centrifugal
force.
[0014] The rotating step in the string trimming mode may include
the step of rotating the motor in a first direction, and the
rotating step in the blade trimming mode may include the step of
rotating the motor in a second direction, opposite from the first
direction. The method may still further include preventing string
spool feeding in the blade trimming mode. In another step, the
method includes effecting a blower function using the motor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] These and other aspects and advantages of the present
invention will be described in detail with reference to the
accompanying drawings, in which:
[0016] FIG. 1 is a perspective view of the trimming tool
incorporating a blade attachment according to the present
invention;
[0017] FIG. 2 is a bottom view of the trimming tool with the blade
attachment removed showing the string spool housing;
[0018] FIG. 3A is a plan view of the blade attachment with the
first covering disc removed;
[0019] FIG. 3B is a plan view of the second disk;
[0020] FIG. 3C is a plan view of the blade assembly attached to the
trimming tool;
[0021] FIGS. 3D and 3E illustrate an alternative blade
assembly;
[0022] FIG. 4 is a perspective view of a spool lock used in
conjunction with the present invention;
[0023] FIG. 5A is a plan view of an another alternative blade
assembly;
[0024] FIG. 5B is a side view of the blade assembly illustrated in
FIG. 5A;
[0025] FIG. 6 is a close-up view of an inertial lock in the
embodiment illustrated in FIG. 5A;
[0026] FIG. 7 is a cross-sectional view according to a third
embodiment of the present invention; and
[0027] FIGS. 8A-8D illustrate structure effecting a blower function
according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0028] Referring to FIG. 1, a trimming tool 10 in accordance with a
preferred embodiment of the invention is shown. The trimming tool
10 includes a handle assembly 12 coupled via a shaft 14 to a
trimming assembly 16. Operator functions are accessed by
conventional switches and the like at the handle. The tool 10
includes a motor having an output shaft and a string spool housing
22 attached to the output shaft for rotation by the motor. The
string spool housing 22 spools a cutting string for the tool in a
known manner. Additionally, the string spool housing 22
incorporates a known automatic string feed mechanism that utilizes
centrifugal force to sense a string breakage as described in U.S.
Pat. Nos. 4,607,431 and 5,063,673, the disclosures of which are
hereby incorporated by reference. Upon such a breakage, the
mechanism effects automatic feeding of the string from the string
spool housing 22.
[0029] As shown in FIG. 2, a bottom surface of the string spool
housing 22 according to the invention is provided with one or more
lugs 28 secured thereto for rotation with the string spool housing
22. In a preferred arrangement, the string spool housing 22 is
provided with two lugs 28 disposed 180.degree. apart. In the first
embodiment according to the present invention, the blade attachment
is coupled to the trimming tool 10 via the lugs 28 on the string
spool housing 22 and a center shaft 29.
[0030] Referring to FIGS. 3A-3C, the first preferred embodiment of
the invention will be described in detail. The blade attachment 30
according to the first embodiment of the invention includes a first
disc 32 that is engageable with the string spool housing 22 of the
trimming tool via the lugs 28 and the center shaft 29 and a second
disc 34 (see FIG. 1) that sandwiches the inside components of the
blade assembly 30 between the first and second disks 32, 34.
[0031] The first disc 32 includes a pair of arcuate slots 36 formed
radially inward from an outside edge of the first disc 32 about
midway between the edge of the first disc 32 and its center. The
arcuate slots 36 are shaped to receive the lugs 28 secured to the
string spool housing 22. The lugs 28 are displaced in the slots 36
as a function of the rotation direction of the string spool housing
22.
[0032] The first disc 32 supports a pair of pivot posts 38 disposed
substantially 1800 from each other. The pivot posts 38 pivotally
support trimming blades 40 of the blade assembly 30. As shown in
FIGS. 3A and 3C, each trimming blade 40 includes a cutting
component 40A pivoting on one side of the pivot post 38 and a
camming component 40B on another side of the pivot post 38. The
cutting components 40A may be formed with an air foil shaped
cross-section to reduce wind drag during operation.
[0033] In operation, the trimming blades are pivoted to a retracted
position in a string trimming mode and an extended position in a
blade trimming mode. In the string trimming mode, the motor is
operated to drive the string spool housing 22 in the direction
denoted by arrow ST in FIG. 3C. With this rotation, the lugs 28 are
positioned in the arcuate slots 36 in engagement with the camming
component 40B of the trimming blade 40. Consequently, the blades 40
are locked in the retracted position by the lugs 28 engaging the
camming components 40B of the trimming blades 40 and are prevented
from pivoting to their extended position.
[0034] In order to convert the operating mode from the string
trimming mode to the blade trimming mode, the user actuates a
mechanical switch at the handle or the like to reverse the rotation
direction of the motor. The motor thus drives the string spool
housing 22 in the direction denoted by arrow BT in FIG. 3C. As a
result, the lugs 28 are shifted (clockwise in FIG. 3C) along the
arcuate slots 36 to the opposite end of the arcuate slots as shown
in FIG. 3C. With the lugs 28 shifted to this position, the lugs 28
are disengaged from the camming component 40B of the trimming blade
40, and the trimming blades are free to pivot about the pivot posts
38 by centrifugal force.
[0035] The trimming blades 40 are preferably biased toward the
retracted position by a torsion spring 42 or the like secured
between each trimming blade 40 and the first disc 32. The torsion
springs 42 are secured in spring slots 43 formed in the first disc
32 as shown in FIG. 3B. In the blade trimming mode, the centrifugal
force acting on the trimming blades is greater than the bias
effected by the torsion spring 42. The torsion spring 42 also acts
as a displaceable stop for the trimming blades by the spring slot
43, defining a fully extended position. The spring 42 enables the
blades to be hyper-extended in the event of contact with a hard
object or the like to prevent breakage of the blades.
[0036] When the motor is stopped, the torsion spring 42 urges the
trimming blades back to the retracted position. If the user elects
to convert back to the string trimming mode by again reversing the
rotation direction of the motor, the lugs 28 engage the camming
components 40B of the trimming blades 40 to urge and lock the
trimming blades 40 into the retracted position.
[0037] The string 44 is spooled about the string spool housing 22
in a conventional manner. From the string spool housing 22, the
string is guided via apertures and spring guides to a cutting
position. In the blade trimming mode, the string 44 remains
extracted but is ineffective as the string guides and the like
guide the string to a position directly behind the extended
trimming blade 40. By positioning the string in this manner, the
string 44 will draft behind the trimming blade 40, thereby reducing
drag resistance by the spring and increasing fuel or electrical
efficiency and motor output.
[0038] In the event of string breakage in the string trimming mode,
the trimming tool 10 is provided with the automatic feed mechanism
as mentioned above. In general, the automatic feed mechanism
utilizes a lock lever to lock and release the string spool housing
22 using centrifugal force generated by a desired length of string.
In the event of string breakage during use, the centrifugal moment
of the string is reduced to release the locking mechanism, and
string is fed from the string spool housing 22 until the string
length creates a sufficient centrifugal moment to re-actuate the
spool locking mechanism. The details and structure of the
auto-feeding mechanism are described in the above-referenced U.S.
patents, which are hereby incorporated by reference, and further
detail will not be provided.
[0039] In the blade trimming mode, it is necessary to deactivate
the automatic string feeding mechanism as the extended blades have
an unpredictable result and effect on the centrifugal moment of the
string. For this purpose, a spool lock 46 is secured to a raised
connector 48 in the first disc 32. Referring to FIG. 4, the spool
lock 46 includes a shaped connecting aperture 50 engaging the
raised connector 48 (FIG. 3B) of the first disc 32 and a locking
tab 52 coupled via an arm 54 or the like to the shaped connecting
aperture 50 and extending through a spool lock slot 56 (FIG. 3B) in
the first disc 32. The shaped connecting aperture 50 is slightly
larger in one dimension (e.g., width in FIG. 3C) than the raised
connector 48 of the first disc 32. As a consequence, the spool lock
46 is shiftable on the raised connector 48 by an amount defined by
the size of the shaped connecting aperture 50. The spool lock 46 is
shiftable by centrifugal force between a releasing position in the
string trimming mode and a locking position in the blade trimming
mode.
[0040] As shown in FIG. 3C, in the string trimming mode, a front
end of the arm 54 of the spool lock 46 engages the trimming blade
40 in its retracted position. In the string trimming mode with the
trimming blades 40 locked in the retracted position, the spool lock
46 is prevented from being shifted forward into the locking
position by one of the trimming blades 40. In the releasing
position, the automatic string feed is functional in its normal
manner. In the blade trimming mode as described above, the trimming
blades 40 are pivoted to their extended position by centrifugal
force, and the spool lock 46 is free to shift by centrifugal force
to the locking position. In the locking position, the locking tab
52 acts against an inside diameter of the string spool housing 22
to thereby prevent string feeding. The string spool housing 22 may
be provided with posts or locking ribs 57 or the like (see FIG. 2)
in its inside diameter for this purpose.
[0041] As shown in FIGS. 3A and 3C, the camming component 40B of
the trimming blade 40 is preferably thinner than the cutting
component such that in the retracted position, the cutting
component engages the arm 54 of the spool lock 46, thereby
preventing the spool lock 46 from shifting to the locking position,
and in the extended position, the camming component 40B of the
trimming blade 40 can be pivoted between the arm 54 of the spool
lock and the first disc 32. In this manner in the event that the
trimming blade 40 is hyper-extended beyond the displaceable stop by
the torsion spring 42 during operation, e.g., by hitting a hard
object, the camming component 40B passes between the arm 54 of the
spool lock and the first disc 32, and the trimming blade 40 is
protected from damage.
[0042] The second disc 34 is fitted to the pivot posts 38 by
apertures or the like and secured at its center by any suitable and
well-known securing structure such as a snap ring or the like. The
second disc 34 sandwiches components of the blade assembly and
secures the trimming blades 40 on the pivot posts 38.
[0043] Another embodiment of the invention is illustrated in FIGS.
3D and 3E. In this alternative arrangement, the blade assembly 30
of the first embodiment is replaced with a modified blade assembly
30', wherein the lugs 28 are replaced with blade pivot pins 28'
secured to a driver disc 32', which in turn is coupled for rotation
with the string spool housing 22. The driver disc 32' forms part of
the string spool housing 22. The pivot pins 28' in the driver disc
32' pivotally support the trimming blades 40' and engage arcuate
slots 36' in a driven disc 34'. The driven disc 34' also includes
stop pins 37 attached thereto.
[0044] In operation, in the string trimming mode, the motor drives
the spool housing in the direction indicated by arrow ST. The pivot
pins 28' are shifted to corresponding ends of the slots 36'
(clockwise in FIG. 3D) by the rotation direction of the driver disc
32'. The stop pins 37 in the string trimming mode prevent the
blades 40' from pivoting outward, and thereby serve as a locking
mechanism for the blades 40'.
[0045] When the operator desires to operate the tool in the blade
trimming mode, the motor is reversed and driven in the direction
indicated by arrow BT in FIG. 3D. The pivot pins 28' then shift
along the arcuate slots 36' (counterclockwise in FIG. 3D) to the
opposite end of the slots 36', and the trimming blades 40' are
freed to pivot to their extended positions by centrifugal force
(shown in phantom in FIG. 3D). When the motor is stopped, the
blades 40' may be returned to their retracted position by engaging
the pivot pins 37 as the motor drives the spool housing in the
string trimming mode direction, or the blades may be spring biased
toward their retracted position.
[0046] Similar to the first embodiment, the assembly according to
this embodiment incorporates a spool lock to prevent string feeding
in the blade trimming mode.
[0047] According to another preferred embodiment of the invention,
referring to FIGS. 5A, 5B and 6, the first disc 32" is formed in an
oblong shape. The first disc 32" similarly includes arcuate slots
36" receiving lugs 28 secured to the string spool housing 22. In
this embodiment, as seen in FIG. 5A, the arcuate slots 36" are
smaller than the arcuate slots 36 in the first embodiment as the
locking mechanism in this embodiment does not utilize the lugs
28.
[0048] Rather, the slots 36" and slightly modified lugs 28"
cooperate to effect the functionality of the spool lock 46
discussed in connection with the first embodiment. In particular,
the lugs 28" are provided with a cam surface or the like for
cooperation with a corresponding surface on the spool lock 46. In
the string trimming mode, the cam surfaces are disengaged from the
spool lock 46, thereby permitting the automatic string feed
operation. In the blade trimming mode, as the lugs 28" shift along
the slots 36", the cam surface of at least one of the lugs 28"
engages the corresponding surface of the spool lock, thereby
preventing string feeding.
[0049] The first disc 32" supports a modified blade assembly 60
incorporating an inertial lock 62. As opposed to pivot posts 38 as
in the first embodiment, rotatable posts or blade pivots 64 are
rotatably mounted in the first disc 32" with a bearing or the like.
The blade pivots 64 are keyed in a suitable manner as shown in the
FIGURES, and the trimming blade 40" is correspondingly keyed with a
shaped aperture for rotation with the blade pivot 64.
[0050] The inertial lock 62 includes a locking bar 68 pivotally
secured to the first disc 32" and spaced from the blade pivot 64 as
shown in FIG. 5A. The locking bar 68 pivots about a pivot pin 69
attached to the first disc 32". A blade lock plate 70, which is
substantially tear-drop shaped as shown in the FIGURE, is also
keyed to the blade pivot 64 with a shaped aperture or the like for
rotation with the blade pivot. A cover 72 is attached to the first
disc 32" over the inertial lock 62 components by screws or an
ultrasonic seal and secures the trimming blade 40", blade lock
plate 70 and locking bar 68. Both sides of the trimming blade 40"
in this embodiment are formed with a cutting edge, such that in the
event one edge becomes worn, the cover 72 can be removed, and the
trimming blade can be turned over.
[0051] In the string trimming mode, the blade 40" is urged to its
retracted position by a spring, and the locking bar 68 of the
inertial lock 62 is pivoted to a locked position engaged with the
blade lock plate 70, thereby preventing the blade 40" from pivoting
away from its retracted position. When the motor is reversed to
convert the operation from the string trimming mode to the blade
trimming mode, centrifugal force causes the locking bar 68 to pivot
to a released position separated from the blade lock plate 70
(counterclockwise in FIG. 5A as shown in phantom). The trimming
blade 40" is then free to pivot by centrifugal force against the
force of the torsion spring to its extended position for blade
trimming. In this embodiment, the torsion spring is secured between
the first disc 32" and the blade pivot 64 supporting the trimming
blade. When the motor is stopped, the torsion spring urges the
trimming blade 40" back to the retracted position, and the blade
lock plate 70 is passed by the locking bar 68. Upon restart of the
motor in the string trimming mode, centrifugal force shifts the
locking bar 68 back to its locked position before the blade tries
to swing outward.
[0052] This embodiment also incorporates the spool lock 46
discussed in connection with the first embodiment. In addition, the
second disc 34" is attached to the first disc 32" in a manner
similar to that discussed in connection with the first
embodiment.
[0053] Also similar to the first embodiment, the string is guided
from the string spool housing 22 to the exterior of the assembly
such that in the blade trimming mode, the string directly follows
the blade in its extended position. Consequently, the string drafts
with the blade to reduce wind drag and increase system operation
and efficiency. In this embodiment, as shown in FIG. 5B, the
perimeter of the first disc 32" is provided with a chamfered edge
74 to further reduce wind drag.
[0054] As described above, in the embodiments according to the
invention, blade trimming is effected by reversing a rotation
direction of the motor. In each embodiment, a locking mechanism is
selectively engageable with the trimming blade to lock the trimming
blade in its retracted position in the string trimming mode. Each
locking mechanism is structured such that it is reciprocated
between a locked position and an unlocked position based on a
rotation direction of the motor. Additionally, the one or more
trimming blades are biased toward their retracted position by a
torsion spring or the like such that when the motor is stopped in
the blade trimming mode, the blades are automatically retracted
toward their retracted position by the spring.
[0055] A fourth preferred embodiment according to the invention
will be described with reference to FIG. 7. In this alternative
embodiment, the blade trimming mode is effected without reversing
the rotation direction of the motor. Rather, a pull cable 82 or
like actuator is extended at one end to the handle 12 (FIG. 1) and
at its other end is secured to a rotary cam plate 84. The rotary
cam plate 84 contains one or more cam surfaces 86 such that as the
cable 82 is actuated, the rotary cam plate 84 is rotated from a
home position to an end position, which is defined by a stop, and
the cam surfaces 86 shift the rotary cam plate 84 (upwardly in FIG.
7) into engagement with a pair of latch release pins 88. The cam
plate 84 is preferably stamped steel with four cam surfaces formed
on its periphery. The latch release pins 88 are coupled with a
latch 90 that is displaceable by the latch release pins 88 between
a locking position and a releasing position. The latch 90 is
preferably formed of stamped sheet metal or the like.
[0056] In the locking position, as shown in FIG. 7, the latch 90
engages the pivotable trimming blades 40'", thereby preventing the
trimming blades 40'" from pivoting to their extended position by
centrifugal force. A spool housing 92 is provided with suitably
shaped cavities 94 such that when the latch 90 is displaced to the
releasing position, catching portions 90A of the latch are shifted
into the cavities 94 such that the trimming blades 40'" are
released by the latch 90 and can be pivoted to their extended
position by centrifugal force. A spring 96 is disposed in the
cavity 94 to urge the latch 90 toward its locking position. Similar
to previously described embodiments, the trimming blades are biased
toward the retracted position by a torsion spring or the like.
[0057] In operation, when the user desires to switch from the
string trimming mode to the blade trimming mode, the user actuates
the pull cable 82 to rotate the rotary cam plate 84 from its home
position to its end position and thereby release the pivoting
trimming blades 40'". As the motor rotates the assembly, the blades
are pivoted to their extended position against the force of the
torsion spring by centrifugal force. When the motor is stopped, the
blades are pivoted toward the retracted position by the torsion
springs. When the user releases the cable 82 for blade trimming,
the rotary cam plate 84 returns to its home position by another
torsion spring 97, and the latch 90 is returned to its locking
position by the springs 96. Because the latch 90 is returned to its
locking position before the trimming blades have returned to their
retracted position, the trimming blades are prevented from fully
retracting by the catch portion 90A of the latch 90. Thus, in this
arrangement, in order to fully retract the trimming blades, with
the motor stopped, the user merely actuates or pulses the pull
cable 82 to raise the latch 90 and allow the trimming blades to
return to their fully retracted position. In an alternative
arrangement, the catch portions 90A of the latch are provided with
a ramped cam surface facing the blades in the extended position
such that as the blades are returned to their retracted position,
the blades themselves urge the latch 90 upward and out of the
way.
[0058] With continued reference to FIG. 7, in each of the
embodiments described above, the trimming tool is configured such
that string spool or blade replacement can be easily achieved. As
shown, a spool retaining post 98 is provided with a retaining ring
groove or aperture 98A. A cover 102 is fitted within the string
spool housing 92 by a friction fit with an edge 102A. A split
spring steel clip 104 is extended through the retaining ring groove
98A to secure the cover 102 in place.
[0059] To remove or replace the string spool and/or blades, the
split spring steel clip 104 can be lifted and pulled outward to
clear the groove 98A in the spool retaining post 98. The spool
housing cover 102 can then be removed, and the spool 106 can be
lifted for replacement. In a like manner, with the cover 102
removed, the spool housing 92 can be lifted from the assembly to
readily enable blade replacement.
[0060] With the thus described non-reversing alternative
embodiment, the user can readily switch between a string trimming
mode and a blade trimming mode using the pull cable actuator
without requiring implementation of a reversible motor.
[0061] In each of the above-described embodiments, the selectable
blade assembly can be embodied in the trimming tool or separately
as a selectable blade attachment. In the attachment application,
the user can readily add the blade assembly to an existing tool. In
some applications, the user will also be required to replace the
string spool housing with a string spool housing incorporating the
lugs 28. As described above, however, the replacement operation can
be effected without difficulty.
[0062] According to the present invention, each of the preferred
embodiments described above can be provided with a blower function
to increase the functionality of the trimming tool. In a
conventional trimming tool, air flow is generated by at least one
air vane secured to the string spool housing 22. The airflow serves
to cool the motor during operation. After cooling the motor, the
airflow is expelled to the exterior through the tool
components.
[0063] To effect blower functionality, referring to FIG. 8A, a
blower flute or scroll 112 may form part of the unit for guiding
the airflow to an exit opening 114 as a permanent auxiliary blower
capability incorporated into the trimming tool according to the
invention. The fan is first separated from the string spool housing
22, and the blower scroll 112 is inserted between the fan and
spool. The scroll is screwed or otherwise attached to the underside
of the tool guard. The blower flute 112 is thus disposed
surrounding the string spool housing 22, thereby guiding the motor
cooling air toward the exit opening 114. With the air flow thus
directed, the volume and velocity of the air is sufficient for
blowing trimmings and the like from the cutting operation.
[0064] In the embodiments described above, wherein the motor is
reversed to convert from a string trimming mode to a blade trimming
mode, it is important to ensure that there is sufficient cooling
air for the motor during reverse operation. As shown in FIG. 8A, a
second air exit opening 116 is provided in the blower flute
allowing air to cool the motor in the blade trimming mode (i.e.,
when the string spool housing is being rotated in the direction
designated by arrow BT).
[0065] In an alternative arrangement (not shown), an air exit cover
is connected by cable or the like to a handle trim/blow selector
switch. In the trim mode, essentially motor cooling air blows into
the string or blade plane to act as an air boost. In the blow mode,
the cover is full open for mass directed air forward.
[0066] In another alternative arrangement, referring to FIG. 8B, a
two-stage spool housing fan is provided. The two-stage spool
housing fan is coupled with the string spool housing 22. A first
stage 120 is provided with one or more air vanes rotating with the
spool housing 22. The first stage generates cooling air for the
motor by drawing ambient air across the motor and through inlets
122 in the assembly. This air is then directed to a second stage
124, which is also provided with one or more air vanes rotating
with the spool housing 22, via inlets 126. The air vanes in the
second stage 124 direct air flow into a blower scroll 112'
surrounding the fan.
[0067] In yet another alternative arrangement, referring to FIGS.
8C and 8D, a blower attachment 130 is structured for selective
attachment to an existing string trimmer. The blower attachment 130
includes an internal scroll shroud or involute 132 and is fitted
over the motor housing MH to direct the airflow to an exit opening.
FIG. 8D illustrates the manner in which an existing guard G is
fitted over the motor housing MH. This guard G is removed by
disengaging the shoulder assembly from the motor housing MH. The
blower attachment is provided with a corresponding shoulder
assembly 134. The blower attachment is thus readily adaptable to
existing trimming tools.
[0068] According to the present invention, a trimming tool can
enable easy conversion between a string trimming mode and a blade
trimming mode without requiring disassembly of the tool. The
trimming blades are extended to their operating positions by
centrifugal force, in one arrangement by reversing the rotation of
the motor, and in another arrangement by releasing a locking
mechanism using a mechanical actuator. Blower functionality can be
added to the trimming tool as a permanent attachment between the
string spool housing and the tool guard or as an auxiliary
attachment that is readily attachable to existing trimming tools.
The blower assembly directs air generated for cooling the motor to
an air outlet using a blower flute or scroll. Thus, according to
the present invention, a trimming tool is provided with expanded
and diverse functionality.
[0069] Those skilled in the art can now appreciate from the
foregoing description that the broad teachings of the present
invention can be implemented in a variety of forms. Therefore,
while this invention has been described in connection with
particular examples thereof, the true scope of the invention should
not be so limited since other modifications will become apparent to
the skilled practitioner upon a study of the drawings,
specification and following claims.
* * * * *