Note: Descriptions are shown in the official language in which they were submitted.
CA 02551330 2006-06-29
WEDGE CLUTCH ASSEMBLY
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
[0002] The present invention relates generally to gear systems. More
specifically, the invention is a wedge clutch assembly for insertion in power
hand tools and drilling apparatus to prevent damage to a gear drive system
upon excessive stress.
2. DESCRIPTION OF THE RELATED ART
1
CA 02551330 2006-06-29
[0003] The related art of interest describes various clutch assemblies,
but none of the cited references discloses the present invention. There is a
need to provide a mechanism to avoid gear failure in power hand tools and
even in well drilling apparatus. The relevant art will be discussed in the
order
of perceived relevance to the present invention.
[0004] U.S. Patent Application Publication No. 2002/0062967,
published on May 30, 2002, describes an electrical handheld power tool with
an electromagnetic safety clutch provided between a pinion shaft and a rotor
shaft. The pinion shaft is formed as a hollow shaft provided in its interior
with an inner bearing which rotatably supports the pinion shaft. The rotor
shaft has its end received in the interior of the pinion shaft and supported
against the inner bearing. The safety clutch is distinguishable for requiring
an electromagnetic means.
[0005] U.S. Patent No. 3,625,292, issued on December 7, 1971 to
Michael T. Lay, describes an insulated slip clutch for a power cutting tool
such as a lawn edger and grass trimmer. A slip clutch made of Bellville
washer springs is held in place by a retaining nut which allows the D-shaped
2
CA 02551330 2006-06-29
end of the drive shaft to continue to rotate, but to immobilize the drive
pinion and any cutting motion. The slip clutch is housed between the cutting
blade and a plastic casing in two insulating cups and a liner with a D-shaped
hole. The clutch assembly is deemed distinguishable for requiring the
driving shaft end to have a flattened D-shaped cross-section, Bellville washer
springs and a two-cup insulating casing.
[0006] U.S. Patent No. 4,606,443, issued on August 19, 1986 to Misao
Kimura, describes a planetary drive with an overload clutch release means for
a telescopic antenna comprises an intermediate gear which meshes with a
gear portion provided on an inner surface of a driven rotary member and a
clutch gear which meshes with the intermediate gear to comprise the
planetary gears. The clutch assembly is distinguishable for requiring a
planetary drive with an intermediate gear for raising and lowering a
telescopic antenna.
[0007] U.S. Patent No. 3,752,278, issued on August 14, 1973 to Ronald
F. States, describes an improved power operated wrench or screwdriver
having two dog clutches in series for the transmission of the drive in which
3
CA 02551330 2006-06-29
one is a torque sensitive dog clutch having ramped interengaging driving
surfaces adapted to be induced to become displaced against the action of a
spring when the torque applied by the tool exceeds a predetermined value.
The other dog clutch is a non-torque sensitive clutch which is adapted to
become disengaged by displacement of the torque sensitive clutch. The dog
clutches are distinguishable for requiring two having different torque
sensitivities.
[0008] U.S. Patent No. 4,053,980, issued on October 18, 1977 to Arthur
G. Poehlman, describes a chain saw featuring an over-torque releasing clutch
mechanism comprising a drive member driven by the drive shaft and a driven
member for rotating the chain sprocket. One of the members is axially
movable relative to the other between an engaged or driving position and a
released position wherein they are disengaged from each other. The drive
and driven members have intermeshing clutch teeth which co-act to produce
an axial force in a direction tending to separate the members which are
releasably held by a resilient member. The clutch mechanism is
distinguishable for requiring intermeshing clutch teeth.
4
CA 02551330 2006-06-29
[0009] U.S. Patent No. 4,066,136, issued on January 3, 1978 to Karl
Wanner et al., describes a torque and impulse transmitting portable hammer
drill having a safety overload clutch mechanism inserted in series between
the rotary shaft of the motor and the tool to terminate the transmission of
torque from the rotary shaft to the tool when resistance to rotation exceeds a
predetermined value. An intermediate gear with smaller teeth is positioned
between the crank gear and the coupling gear. The clutch is distinguishable
for requiring a third gear.
[0010] U.S. Patent No. 4,809,572, issued on March 7, 1989 to Katsuhiko
Sasaki, describes a power driven screwdriver having a claw clutch comprising
a fixed clutch member with teeth on the end of a main gear on a support
shaft. The spindle has a movable clutch member with teeth and an engaging
ball in an inclined groove. A spring is located between the movable clutch
member and the fixed clutch member. The claw clutch is distinguishable for
requiring engaging teeth and an engaging ball.
[0011] U.S. Patent No. 4,883,130, issued on November 28, 1989 to Paul
H. Dixon, describes a rotating dual speed transmission for a screw fastener
CA 02551330 2006-06-29
driving tool of an automatic assembly machine which acts in conjunction with
two torque-responsive clutches to tighten a threaded fastener such as a
screw or a nut during rotation of the spindle. A first torque-responsive
clutch automatically switches the drive from a fast speed to a slow speed
when torque of a predetermined magnitude is imposed on the fastener, and
a second torque-responsive clutch automatically interrupts the drive to the
fastener when torque of a higher predetermined magnitude is imposed on
the fastener. The first lower clutch has lugs which lock with the lower cam
segments supported with a coil spring around the spindle. The upper clutch
has lugs which lock with the jaw members of the lower clutch. The clutches
are distinguishable for requiring locking elements such as lugs and cam
segments.
[0012] U.S. Patent No. 4,967,888, issued on November 6, 1990 to
Wolfgang Lippacher et al., describes a safety clutch for a motor-driven
hammer drill which breaks the rotational drive train when a working tool
becomes seized in a receiving material. A pair of coupling balls upon seizure
leave their recesses in the power take-off spindle housing to permit the drive
6
CA 02551330 2006-06-29
to continue to rotate. However, the motor must be stopped and restarted.
The safety clutch assembly is distinguishable for requiring coupling balls.
[0013] U.S. Patent No. 5,060,772, issued on October 29, 1991 to Heinz-
Gerhard Anders et al., describes a pneumatic power-operated screw driving
tool which includes a switching clutch to transfer the torque from the drive
shaft to an output shaft when the tool seizes. The driver has a first clutch
having clutch coupling jaws at its end which engages the coupling jaws of the
second clutch. The clutch system is distinguishable for requiring two
engaging clutches with jaws.
[0014] U.S. Patent No. 5,094,133, issued on March 10, 1992 to
Wolfgang Schreiber, describes a power-operated screwdriver with a switch-
off means for screw-in depth and screw-in torque having three clutch
elements. A first clutch element arranged between the drive and the tool
drive shaft, and transferable by axial displacement of the tool drive shaft
from a rest position to a working position. A second clutch element
connected to the tool drive shaft. A third clutch element arranged between
the first and second clutch elements forms an entrainment clutch with the
7
CA 02551330 2006-06-29
first clutch element and forms a release clutch with the second clutch
element. The clutch system is distinguishable for requiring three connecting
clutches.
[0015] U.S. Patent No. 5,134,909, issued on August 4, 1992 to
Katsuhiko Sasaki, describes a power driven screwdriver including a driving or
frictional clutch mechanism interposed between the drive motor and the
spindle. A claw clutch mechanism is interposed between the spindle and a
second driving member which is separated from a first driving member. The
clutch system is distinguishable for requiring a frictional clutch and a claw
clutch.
[0016] U.S. Patent No. 5,138,916, issued on August 18, 1992 to Yuichi
Sato et al., describes a power operated screwdriver having two clutches, a
compression spring between a support shaft and an intermediate clutch disc
and urges the clutch disc toward the main spindle to disengage the first
clutch. The clutch system is distinguishable for requiring two clutches.
[0017] U.S. Patent No. 5,350,026, issued on September 27, 1994 to
Heule Markus et al., describes an electric power-driven screw-driver having a
8
CA 02551330 2006-06-29
single friction coupling consisting of first and second coupling elements that
undoes the drive connection between a driving electric motor and the tool
output shaft.
[0018] U.S. Patent No. 5,372,206, issued on December 13, 1994 to
Katsuhiko Sasaki et al., describes a tightening tool including a drive member
rotatably driven by a motor. An intermediate member is interposed between
the drive member and a spindle, and rotatable with the drive member. A
claw clutch is formed between the spindle and the drive member. The clutch
system is distinguishable for requiring a claw clutch.
[0019] U.S. Patent No. 5,538,089, issued on July 23, 1996 to
Christopher P. Sanford, describes a power tool clutch assembly having a first
spindle configured to rotate in a gear case. A drive clutch element is fixed
to
the first spindle. A second spindle rotates independently of the first
spindle.
An output clutch element is fixed to the second spindle. A compression
spring is provided between the intermediate and output clutch elements.
The clutch housing and clutch components can be removed from a power
9
CA 02551330 2006-06-29
tool gear casing for easy service. The clutch assembly is distinguishable for
requiring two clutches.
[0020] U.S. Patent No. 5,566,458, issued on October 22, 1996 to
Thomas R. Bednar, describes two embodiments of a clutch mechanism for
reciprocating saws having a wobble plate drive member including a spindle
reciprocally supported by the housing, and a clutch drivingly connecting the
motor to the shaft and providing slippage between the motor and the shaft if
there is binding of the spindle. The clutch mechanisms are distinguish-able
for requiring structurally different elements.
[0021] U.S. Patent No. 5,573,091, issued on November 12, 1996 to
Michael Hung, describes an electrically powered or manually driven clutch
and brake assembly for an electric winch cooperating with a transmission
assembly. The clutch mechanism is provided with a thrust bearing on a
clutch shaft, and a large clutch gear is inserted thereon. A lining plate is
attached to a clutch plate of the large gear, and a pinion gear is attached
tightly to the lining plate. Another thrust bearing is placed behind the
pinion
gear and a compression spring is inserted on the clutch shaft. The large gear
CA 02551330 2006-06-29
and the pinion gear are pushed tightly together or loosened as a function of
the resiliency of the spring. A clutch hand wheel can be provided for manual
operation. The clutch mechanism is distinguishable for requiring a large
clutch gear, a lining plate and two thrust bearings.
[0022] U.S. Patent No. 5,622,230, issued on April 22, 1997 to David A.
Giardino et al., describes a rotary impact wrench clutch comprising a two-
part, readily assembled and disassembled pin cage-coupler. One part is a
cylindrical, longitudinally grooved cage contains a clutch mechanism and
capped at one end by a lobed end plate coupler. The clutch device is
distinguishable for requiring a pin-cage coupler.
[0023] U.S. Patent No. 5,778,989, issued on July 14, 1998 to Anton
Neumaier, describes a manually operable screw driving tool having a drive
pinion axially fixed with a housing. A spindle in the housing is axially
displaceable relative to the drive pinion against the force of a first spring.
A
clutch element is located in a passageway in a collar on the drive pinion, and
is radially displaceable by an actuating member for engaging the spindle to
the drive pinion. In the engaged position the clutch element sits against a
11
CA 02551330 2006-06-29
stop surface in the spindle. The actuation member is axially displaceable by
stops located on the spindle, and can be axially fixed to the drive pinion by
a
retaining element and a snap-element. The clutch element is distinguishable
for requiring an actuation member axially displaceable by stops on the
spindle.
[0024] U.S. Patent No. 6,283,226 B1, issued on September 4, 2001 to
Kenneth Chen, describes a clutch-buffer assembly for a power wrench
comprising a driven wheel having an outwardly positioning tube disposed at
a power-input end. A retaining spring, a retaining disc, a driven gear, an
anchor ring, and a reversible motor are collared onto the positioning tube
sequentially. The retaining disc is limited to move back and forth along the
positioning tube without rotation. A pair of protruding teeth and reception
cavities in respective contact faces of the retaining disc and the driven
gear,
and the reversible motor is used to drive the driven gear. When the driven
wheel rotates at a higher speed, the retaining disc can be detached from the
driven gear for control of the power consumption to lessen the imposed load
in order not to blow a fuse. The clutch-buffer assembly is distinguishable
12
CA 02551330 2006-06-29
for requiring a pair of protruding teeth and reception cavities in the
respective contact faces of the retaining disc and the driven gear.
[0025] U.S. Patent No. 6,439,091 B1, issued on August 27, 2002 to John
E. Dibbern et al., describes a clutch mechanism for a power tool having a
hole and first and second clamps connected to the arbor to clamp the blade.
One of the cutting tool and at least one of the first and second clamps and
arbor have a first drive surface for contacting a second drive surface on the
other of the cutting tool, and at least one of the first and second clamps and
arbor. The second drive surface is movable between a first position and a
second position bypassing the first drive surface. The second drive surface is
resiliently connected to the other of the cutting tool and at least one of the
first and second clamps and arbor. At least one metal strip connects the
second drive surface to the other of the blade and at least one of the first
and second clamps and arbor. The clutch mechanism is distinguishable for
requiring two clamps for the blade and first and second drive surfaces.
[0026] German Patent Publication No. 3,807,308, published on
September 14, 1989, describes a radially acting safety friction clutch
13
CA 02551330 2006-06-29
positioned inside a component of a power tool with an axial mode of action
to obtain a shorter and more compact tool. The clutch has compression or
cup springs. The clutch is distinguishable for requiring a radially acting
safety friction clutch assembly.
[0027] German Patent Publication No. 4,101,705, published on March
26, 1992, describes a positive, frictionless clutch for a hedge trimmer which
has a locking ring to disengage the main gear from a driven bushing by
moving two drive rollers into a clear space. The clutch assembly comprises a
main drive gear, the driven bushing and a locking ring mounted co-axially on
a fixed central shaft. One end of the drive bushing has eccentrics which
drive the trimmer blades. Roller located in apertures of the driven bushing
transmit the drive through ledges on the inside diameter of the main drive
gear. When the trimmer handle grips are released a stop pin enters a hole in
the flange of the locking ring and prevents rotation. The main drive gear and
the driven bushing continue rotating, causing the rollers to enter a clear
space between the two members and immediately disengaging the drive. A
preloading coil spring connects the locking ring to the driven bushing, and
14
CA 02551330 2006-06-29
together with friction brings the trimmer blades to rest. The clutch assembly
is distinguishable for requiring an eccentric drive bushing containing two
rollers.
[0028] French Patent Publication No. 2,799,113, published on April 6,
2001, describes a jointed dental hand drill as a continuously rotating
instrument having a torque limiter in the form of a spring-loaded sliding
gear clutch on the primary drive shaft and a fixed gear on the secondary
drive shaft. In the event of a set torque being exceeded, the sliding gear
moves along the primary shaft against the pressure of the spring and
disengages the transmission. The two gears have asymmetrical teeth to give
different torque levels according to the direction of motion. The dental drill
clutch system is distinguishable for requiring asymmetrical gear teeth on two
gears.
[0029] None of the above inventions and patents, taken either singly or
in combination, is seen to describe the instant invention as claimed. Thus, a
wedge clutch assembly solving the aforementioned problems is desired.
SUMMARY OF THE INVENTION
CA 02551330 2006-06-29
[0030] The present invention is directed to multiple embodiments of a
wedge clutch assembly requiring a minimum of space for inclusion in any
electric or pneumatic power tool and drilling rig to prevent damage to an
electrically powered rotary or reciprocal hand drill, screwdriver, well drill,
and
the like tool or apparatus. The first embodiment utilizes the wedge clutch
assembly on a pinion or drive shaft having a configuration sequentially as a
first small diameter and a proximate threaded region, a second conical
region increasing in diameter, a third increased diameter region, a fourth
gear region, and a fifth decreased diameter region. A steel clutch wedge
spring washer is positioned adjacent the pinion gear, and a retaining nut is
threaded on the proximate threaded region for retaining the steel clutch
wedge spring washer. A clutch cup is inserted on the conical enlarged region
of the pinion shaft and inside the pinion gear.
[00311 A thrust bearing may be disposed on the pinion or drive shaft.
The thrust bearing may be disposed either between the spring washer and
the pinion gear, or between the retaining nut and the spring washer. The
thrust bearing helps to take pressure off of the retaining nut.
16
CA 02551330 2006-06-29
[0032] The second embodiment utilizes a pinion gear having a
throughbore with inclined sides; a cylindrical pinion shaft having a conical
enlarged region proximate to a first end thereof for supporting the pinion
gear and a second end having a threaded region; and a bearing spacer
element, a bearing, a clutch wedge spring steel washer, and a retaining nut
sequentially secured on the threaded region of the pinion shaft.
[0033] A third embodiment utilizes a driven cylindrical motor shaft; a
clutch cup having a first enlarged region adapted with a keyway for passing
said motor shaft therethrough; the clutch cup having a second conical
reduced region and a third externally threaded neck region; a sprocket wheel
frictionally fitted on the second conical reduced region of the clutch cup; a
steel clutch wedge spring washer positioned adjacent the sprocket wheel;
and a nut retaining the steel spring washer on the motor shaft. Further
embodiments, including the addition of a housing in order to protect the
wedge clutch assembly from environmental contamination, are further
described.
17
CA 02551330 2006-06-29
[0034] Accordingly, it is a principal object of the invention to provide a
wedge clutch assembly for hand tools and drilling rigs.
[0035] It is another object of the invention to provide a wedge clutch
assembly incorporating a clutch wedge spring washer.
[0036] It is a further object of the invention to provide a wedge clutch
assembly incorporating a clutch cup.
[0037] Still another object of the invention is to provide a wedge clutch
assembly adaptable to several different pinion and drive shafts.
[0038] It is an object of the invention to provide improved elements and
arrangements thereof for the purposes described which is inexpensive,
dependable and fully effective in accomplishing its intended purposes.
[0039] These and other objects of the present invention will become
readily apparent upon further review of the following specification and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
18
CA 02551330 2006-06-29
[0040] FIG. 1 is a schematic elevational view of a first embodiment of a
wedge clutch assembly for installation in a hand tool or a drilling rig
according to the present invention.
[0041] FIG. 2 is an exploded elevational view of the FIG. 1 wedge clutch
assembly according to the present invention.
[0042] FIG. 3 is a schematic eievational view of a second embodiment of
a wedge clutch assembly for installation in a hand tool or a drilling rig
according to the present invention.
[0043] FIG. 4 is an exploded elevational view of the FIG. 3 wedge clutch
assembly according to the present invention.
[0044] FIG. 5 is a schematic elevational view of a third embodiment of a
wedge clutch assembly for installation in a hand tool or a drilling rig
according to the present invention.
[0045] FIG. 6 is a perspective view of the FIG. 5 wedge clutch cup
according to the present invention.
19
CA 02551330 2006-06-29
[0046] FIG. 7 is a schematic elevational view of a wedge clutch assembly
according to the present invention similar to FIG. 1, but including a thrust
bearing.
[0047] FIG. 8 is an exploded view of the clutch assembly of FIG. 7.
[0048] FIG. 9 is an exploded view of a wedge clutch assembly similar to
FIG. 8, but with the thrust bearing disposed between the spring washer and
the jam nut.
[0049] Fig. 10 is a side view of a frustoconical section of an alternative
embodiment of the wedge clutch assembly according to the present
invention.
[0050] Fig. 11 is a top view of the frustoconical section of the wedge
clutch assembly of Fig. 10.
[00511 Fig. 12 is a partial side cut-away view of another alternative
embodiment of the wedge clutch assembly according to the present
invention.
[0052] Fig. 13 is a top view of a frustoconical section of the wedge
clutch assembly of Fig. 12.
CA 02551330 2006-06-29
[0053] Fig. 14 is a partial side cut-away view of yet another alternative
embodiment of the wedge clutch assembly according to the present
invention, illustrating the frustoconical section housed within a protective
housing.
[0054] Fig. 15 is a side attachment view of a frustoconical section and a
corresponding sealing bolt according to yet another embodiment of the
wedge clutch assembly according to the present invention.
[0055] Fig. 16 is an exploded partial side cut-away view of yet another
alternative embodiment of the wedge clutch assembly according to the
present invention.
[0056] Similar reference characters denote corresponding features
consistently throughout the attached drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0057] The present invention is directed to three embodiments of a
wedge clutch assembly that can be utilized in rotatable electrically or
pneumatically driven machinery, such as hand tools and drilling rigs, which
would prevent expensive broken gear damage.
21
CA 02551330 2006-06-29
[0058] A first embodiment 10 of a wedge clutch assembly is illustrated
in FIGS. 1 and 2. A pinion gear 12 has a through-bore 14 with inclined sides
16 to define a frustoconical configuration and a countersink 18 on its upper
surface to frictionally accommodate a spring washer 46. A cylindrical pinion
drive shaft 22 has in sequence from the top, a first small diameter neck 24
and a proximate threaded region 26, a second frustoconical region 28
increasing in diameter, a third increased diameter region 30, a fourth gear
region 32, and a fifth decreased diameter region 34. The pinion gear 12
revolves with the pinion driven shaft 22 in order to drive a drill bit or
other
load. A fillet 36 is provided to support the frustoconical region 28 on one
side and fillets 36 are also provided on both sides of the gear region 32.
[0059] The frustoconical bronze clutch cup 20 is 1/16 inch thick (shown
also in FIG. 6) and has a wide aperture 40 and a smaller aperture 42. The
bronze clutch cup 20 is inserted inside the throughbore 14 of the pinion gear
12 and fits over the frustoconical region 28 of the pinion drive shaft 22 to
prevent the pinion gear 12 and the pinion drive shaft 22 from gouging or
otherwise damaging the clutch wedge spring washer 46 by shear forces. The
22
CA 02551330 2006-06-29
spring washer 46 is shaped as a shallow cup with open ends. The clutch
wedge spring washer 46 is made of spring steel and is placed inside the
countersink 18 and over the smaller aperture 42 of the clutch cup 20. A
fastener, such as a retaining nut or jam nut 48, is placed on the externally
threaded region 26. The jam nut 48 secures the spring washer 46 to the
assembly and adjusts the sensitivity of the clutch wedge spring washer 46, or
frictional force applied by the spring washer 46 to the pinion gear 12, in the
countersink 18 to a specific applied torque on the drive shaft 22 of the tool,
which will energize the clutching action to eliminate any damage to the
mechanical drive system of the tool.
[0060] Under normal load the spring washer 46 applies sufficient
frictional force against the pinion gear 12 to cause the pinion gear 12 to
rotate with shaft 22 to drive the load. However, the clutch wedge spring
washer 46 collapses and assumes a more flattened shape when excessive
torque is applied to the main drive system by the load in order to permit the
pinion gear 12 to stop and the pinion drive shaft 22 to spin freely under an
excessive load. This prevents the gears from being stripped or damage to
23
CA 02551330 2006-06-29
the motor when the load requires more torque than the motor can supply.
This principle applies to all of the embodiments described herein.
[00611 As shown in FIGS. 7-9, a thrust bearing may be disposed
between the pinion gear 12 and the jam nut 48 to relieve pressure on the
jam nut 48 and to prevent premature wear of the spring washer 46. In FIGS.
7 and 8, the thrust bearing 45 is disposed between the pinion gear 12 and
the spring washer 46. In this configuration, under normal load the spring
washer 46 exerts sufficient tension against the thrust bearing 45 to cause
the bearing 45 to frictionally engage pinion gear 12, causing pinion gear 12
to rotate with shaft 22, thereby driving the load. When the load exerts
excessive torque on pinion gear 12, spring washer 46 collapses and flattens,
relieving the frictional force exerted by the spring washer 46 on bearing 45,
thereby permitting pinion gear 12 to stop while shaft 22 rotates freely.
[0062] Alternatively, the thrust bearing 45 may be disposed between the
jam nut 48 and the spring washer 46, as shown in FIG. 9. In this
configuration the spring washer 46 again directly exerts frictional force
against the pinion gear 12 by contact with the wall of the pinion gear 12 in
24
CA 02551330 2006-06-29
countersink 18 under normal load, but collapses and flattens under excessive
torque applied by the load to disengage pinion gear 12 from shaft 22 to
allow free rotation of the shaft 22. Thrust bearing 45 relieves pressure
against jam nut 48 and prevents excessive wear of spring washer 46.
[0063] FIGS. 3 and 4 depict a second embodiment of a wedge ciutch
assembly 50 comprising a pinion gear 52 having a frustoconical throughbore
54 with inclined sides 56 for accepting a bronze clutch cup 58. The pinion
gear 52 has a reinforcement ring 59 on the smaller opening of the
throughbore 54. A cylindrical pinion shaft 60 has a frustoconical enlarged
region 62 proximate to a first end 64 thereof for supporting the pinion gear
52 and a second end 66 having an externally threaded region 68. A bearing
spacer element 70 with a shoulder 72 supports a bearing 74 with evenly
spaced blind bores 76, a steel clutch wedge spring washer 78 which is
inverted, and a retaining jam nut 80 sequentially secured on the threaded
region 68 of the pinion shaft 60, whereby the pinion gear 52 revolves with a
pinion gear of a driven shaft (not shown). Again, the sensitivity of the
clutch
wedge spring washer 78 is adjusted by the amount of pressure exerted by
CA 02551330 2006-06-29
the jam nut 80. Upon excessive torque on the driven shaft due to sticking in
a bore, the clutch wedge spring washer 78 will compress to disengage the
pinion gear 52 from the driven gear to avoid damage to the driving system of
the tool.
[0064] FIG. 5 shows a third embodiment 82 of a wedge clutch assembly
for a sprocket drive wheel 84 having cogs 102 on a driven cylindrical motor
shaft 86. A bronze clutch cup 88 is provided with a first enlarged region 90
adapted with a keyway 92 for passage of the motor shaft 86 therethrough.
The clutch cup 88 has a second frustoconical reduced region 94 and a third
externally threaded neck region 96. The driven sprocket wheel 84 is
frictionally fitted on said second frustoconical reduced region 94 of the
clutch cup 88. A steel clutch wedge spring washer 98 is positioned abutting
the driven sprocket wheel 84, and its sensitivity is adjustably maintained by
a
jam nut 100 on the threaded neck region 96. Thus, the driven sprocket
wheel 84 is protected from damage by the efficient operation of the steel
clutch wedge spring washer 98 on the motor shaft 86.
26
CA 02551330 2006-06-29
[0065] FIG. 6 illustrates a bronze clutch cup 20 used in the first two
embodiments having a wide lower aperture 40 and a narrow upper aperture
42 to define a frustoconical configuration. The clutch cup preferably has a
peripheral thickness between 1/ 16 of an inch and 3 inches. As noted above,
clutch cup 20 is the only element in the wedge clutch assemblies made of
bronze, the remaining elements being made of hardened steel.
[0066] It should be noted that it may be desirable, in the alternative, to
remove clutch cup 20 from the wedge clutch assembly. By forming
frustoconical region 16 and frustoconical section 28 from relatively soft
materials, clutch cup 20 may be removed from system 10 without affecting
operation of the clutch assembly. Such a configuration may be desirable in
that friction between the moving parts will be decreased, and the chances for
misalignment between the frustoconical pieces are minimized.
[0067] In the alternative embodiments illustrated in Figs. 10, 11 and 12,
the furstoconical section 28 and upper externally threaded neck 24 are
formed as a unitary structure having a channel 100 formed axially
therethrough. Channel 100 receives a central shaft 120, which drives
27
CA 02551330 2006-06-29
rotation of the wedge clutch assembly. As best shown in the top view of Fig.
11, channel 100 is patterned to include a plurality of axially extending
projections, forming an engaging inner wall surface 110. In Fig. 12, central
shaft 120 has a substantially cylindrical contour, however, depending on the
needs of the user, shaft 120 could be contoured to include corresponding
axially extending projections, forming an engaging outer wall surface for
inner wall surface 110 of Fig. 11. Engagement of the extending projections
of inner wall surface 110 with those of the outer wall surface of the shaft
120
releasably locks shaft 120 to furstoconical section 28 and neck portion 24.
This releasable locking of shaft 120 aids in driving rotation of the
frustoconical section 28 and wedge clutch assembly 10 when shaft 120 is
driven by an external motive force.
(0068] Further, in the embodiment illustrated in Fig. 12, a housing 130
is provided for covering the upper externally threaded neck portion 24 and
the frustoconical section 28. Clutch assemblies are typically used in
combination with some sort of motor, engine or other rotary machine. Thus,
clutch assemblies are often exposed to dirt and other contaminants and
28
CA 02551330 2006-06-29
pollutants which can clog the moving parts of the clutch assembly. The
embodiment illustrated in Fig. 12 is well adapted for usage with lawn mower
blades and the like. Cover 130 is provided to prevent clogging and
contamination of the rotary section of the clutch assembly 10, when used in
combination with a rotary drive system. A removable lid 140 is provided to
allow the user selective access to the interior of housing 130 for repair or
replacement of parts. Removable lid 140 is secured to housing 130 through
a plurality of releasable securement elements, such as, for example, screws
or bolts 150, as shown.
(0069] Additionally, a threaded bore hole 160 may be formed through
frustoconical section 28, extending radially therethrough from the outer
surface of frustoconical section 28 to channel 100, as best shown in the top
cut-away view of Fig. 13. The user may insert a threaded engaging member,
such as a screw or a bolt, for selective locking engagement with central shaft
120, thus securing shaft 120 to the frustoconical section 28 and upper neck
portion 24. This additional locking engagement may be used with a smooth
or keyed shaft, such as that shown in Fig. 12, a patterned shaft as would be
29
CA 02551330 2006-06-29
necessary for the embodiment of Fig. 11, or may be used with a shaft
contoured dependent upon the needs and the desires of the user.
Additionally, as further shown in Fig. 12, housing 130 may be contoured to
include threads or the like for securely receiving and holding the threads 26
of threaded neck portion 24.
[0070] In the alternative embodiment shown in Fig. 14, the upper
portion (in the configuration as shown) of frustoconical section 28 is housed
within a first housing 170. First housing 170 includes an open upper end
and an open lower end. A gasket or o-ring 210 is received within the open
upper end of first housing 170, preventing contamination from dirt and other
contaminants where the remainder of cylindrical pinion shaft 22 projects
outwardly therefrom. The embodiment of Fig. 14 is well adapted for usage
with the drive lines of heavy duty vehicles and the like.
[00711 The open lower end of first housing 170 is in communication
with a second housing 180, which receives the remainder of frustoconical
section 28 and the threaded neck portion 24. The lower end of second
housing 180 is open and is covered with a releasable lid 190. Similar to that
CA 02551330 2006-06-29
shown in Fig. 12, lid 190 is releasably held to housing 180 by a plurality of
securement elements 200, which may be bolts, screws or the like.
[0072] In the similar embodiment shown in Fig. 16, a single housing
240 is provided for receiving and covering frustoconical section 28 and
threaded neck portion 24. The remainder of pinion shaft 22 projects
downwardly and outwardly from the lower end of housing 240, and a gasket
or o-ring 210 is provided for sealing the open lower end of housing 240
about the shaft. The embodiment of Fig. 16 is well adapted for use with
marine-type vehicles and the like.
[0073] The open upper end 250 is adapted, sized and contoured to
receive thrust bearing 74, a pair of fasteners, such as nuts 280, a washer 290
sandwiched between the fasteners 280, and a locking fastener 300. Washer
290 may be a locking-type washer for preventing further movement of jam
nuts 280. Particularly, washer 290 may be a keyed locking-type washer.
Additionally, at least one elastic element, such as a disc spring, 270, is
provided, as shown. Though shown as a stack of three disc springs, it
31
CA 02551330 2006-06-29
should be understood that the number of elastic elements and the type of
elastic elements used is dependent upon the needs and desires of the user.
[0074] Each of the fasteners 280 and 300 have threaded passages
formed centrally therethrough, for engaging threads 26 of neck portion 24.
Additionally, a second gasket or o-ring 310 may be provided within the
passage formed through fastener 300, for forming a seal against
contamination with neck portion 24. Additionally, a third gasket or o-ring
320 may be provided around the external surface of fastener 300 in order to
form a seal with the inner wall of housing 240, which defines opening 250.
[0075] Further, a vertical channel 260 may be formed in the external
surface of threaded neck portion 24, as shown in Fig. 16. The user may
engage vertical channel 260 with an engaging element, such as a bolt or a
screw, in order to selectively and releasably lock threaded neck portion 24 to
housing 240.
[0076] Additionally, under certain conditions, such as in environments
where a great quantity of pollutants might enter the clutch assembly 10, it
may be necessary to seal off the interior of frustoconical section 28. As
32
CA 02551330 2006-06-29
shown in Fig. 15, frustoconical section 28 may have an internal bore passage
230 formed through the upper end thereof. A threaded sealing element,
such as bolt 220, for example, is provided for selective and releasable
engagement with passage 230, to seal the upper open portion of the
frustoconical section 28 from contamination.
[0077] It is to be understood that the present invention is not limited to
the embodiments described above, but encompasses any and all
embodiments within the scope of the following claims.
33
