Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02776713 2012-05-15
WEDGE CLUTCH ASSEMBLY
[0001] 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 rotary power devices to
prevent damage to
a gear or other drive system upon excessive stress.
2. DESCRIPTION OF THE RELATED ART
[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, well drilling apparatus, watercraft
drives, and other
rotary power devices and equipment. The relevant art will be discussed in the
order of
perceived relevance to the present invention.
1
CA 02776713 2012-05-15
[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 Belleville washer springs is held in place by a
retaining nut
which allows the D-shaped 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 one is a torque sensitive
dog clutch having
2
CA 02776713 2012-05-15
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 that 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.
[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
3
CA 02776713 2012-05-15
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 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 that lock
with the lower cam segments supported with a coil spring around the spindle.
The upper
clutch has lugs that 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 that 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 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 screwdriving tool that includes a
switching
clutch to transfer the torque from the drive shaft to an output shaft when the
tool seizes. The
4
CA 02776713 2012-05-15
driver has a first clutch having clutch coupling jaws at its end that 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 is
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 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 that 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.
CA 02776713 2012-05-15
[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 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 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.
6
CA 02776713 2012-05-15
[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 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 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
7
CA 02776713 2012-05-15
distinguishable for requiring an actuation member axially displaceable by
stops on the
spindle.
[0024] U.S. Patent No. 6,283,226 Bl, 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 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 tools 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
8
CA 02776713 2012-05-15
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 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 that 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 that
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 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
9
CA 02776713 2012-05-15
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] Korean Patent Publication No. 1020050005131 published on January 13,
2005
describes (according to the single drawing Figure and English abstract) a
wedge-type clutch
assembly having a male conical component engaging a slotted female conical
component,
with the two conical components contained within a release sleeve. The two
conical
components and the release sleeve are rotationally locked by radial pins.
[0030] 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
[0031] 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,
CA 02776713 2012-05-15
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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] A further embodiment is configured for installation in the propeller
hub of a
watercraft drive system, and serves to prevent damage to the propeller or
drive due to
11
CA 02776713 2012-05-15
excessive torque to the drive in the event the propeller contacts an object.
This embodiment
includes a protective cap at each end thereof to seal the assembly from the
elements.
[0036] Accordingly, it is a principal object of the invention to provide a
wedge clutch
assembly for hand tools and drilling rigs.
[0037] It is another object of the invention to provide a wedge clutch
assembly
incorporating a clutch wedge spring washer.
[0038] It is a further object of the invention to provide a wedge clutch
assembly
incorporating a clutch cup.
[0039] Still another object of the invention is to provide a wedge clutch
assembly
adaptable to several different pinion and drive shafts.
[0040] 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.
[0041] 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
[0042] 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.
[0043] Fig. 2 is an exploded elevational view of the Fig. 1 wedge clutch
assembly
according to the present invention.
[0044] Fig. 3 is a schematic elevational 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.
12
CA 02776713 2012-05-15
[0045] Fig. 4 is an exploded elevational view of the FIG. 3 wedge clutch
assembly
according to the present invention.
[0046] 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.
[0047] Fig. 6 is a perspective view of the Fig. 5 wedge clutch cup according
to the
present invention.
[0048] 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.
[0049] Fig. 8 is an exploded view of the clutch assembly of Fig. 7.
[0050] 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.
[0051] Fig. 10 is a side view of a frustoconical section of an alternative
embodiment of
the wedge clutch assembly according to the present invention.
[0052] Fig. 11 is a top view of the frustoconical section of the wedge clutch
assembly of
Fig. 10.
[0053] Fig. 12 is a partial side cut-away view of another alternative
embodiment of the
wedge clutch assembly according to the present invention.
[0054] Fig. 13 is a top view of a frustoconical section of the wedge clutch
assembly of
Fig. 12.
[0055] 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.
13
CA 02776713 2012-05-15
[0056] 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.
[0057] 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.
[0058] Fig. 17 is an exploded side view of yet another alternative embodiment
of a
wedge clutch assembly according to the present invention.
[0059] Fig. 18 is a partially assembled side view of the wedge clutch assembly
of Fig. 17.
[0060] Fig. 19 is a top view of an outer wedge of the wedge clutch assembly of
Fig. 17.
[0061] Fig. 20 is a side view in section of the wedge clutch assembly of Fig.
17.
[0062] Fig. 21 is an exploded perspective view of another alternative
embodiment of a
wedge clutch assembly according to the present invention, configured for
installation in the
propeller hub of a boat or other watercraft.
[0063] Similar reference characters denote corresponding features consistently
throughout the attached drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0064] 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.
[0065] 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
14
CA 02776713 2012-05-15
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.
[0066] 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
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.
[0067] 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
CA 02776713 2012-05-15
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 the motor when the
load requires
more torque than the motor can supply. This principle applies to all of the
embodiments
described herein.
[0068] 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.
[0069] 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 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.
[0070] Figs. 3 and 4 depict a second embodiment of a wedge clutch 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
16
CA 02776713 2012-05-15
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 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.
[0071] 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 101 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.
[0072] 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
17
CA 02776713 2012-05-15
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.
[0073] 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.
[0074] In the alternative embodiments illustrated in Figs. 10, 11 and 12, the
frustoconical
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 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
frustoconical 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.
18
CA 02776713 2012-05-15
[0075] 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
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 fasteners, such as screws or bolts 150, as shown.
[0076] 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 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.
19
CA 02776713 2012-05-15
[0077] 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.
[0078] 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 shown in Fig. 12, lid 190 is releasably held to housing
180 by a plurality
of fasteners 200, which may be bolts, screws or the like. Lid 190 seals the
internal parts from
external contaminants, and further allows the system to be bolted to one side
of the driveline.
Further, as shown, a washer 75 is sandwiched between a jam nut 71 and an
adjustment nut 73.
These are received about the threaded portion 24, as shown. Further, a pair of
Belleville
springs or disc springs 79 are sandwiched between adjustment nut 73, and a
thrust washer 83.
Thrust bearing 74 is sandwiched between the lower thrust washer 83 and an
upper thrust
washer 81, as shown.
[0079] 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
CA 02776713 2012-05-15
the shaft. The embodiment of Fig. 16 is well adapted for use with marine-type
vehicles and
the like.
[0080] The open upper end 250 is adapted, dimensioned and configured 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 resilient element, such as a
disc spring, 270, is
provided, as shown. Although shown as a stack of three disc springs, it should
be understood
that the number of resilient elements and the type of resilient elements may
vary.
[0081] Each of the fasteners 280 and 300 has a threaded passage formed
centrally
therethrough for engaging threads 26 of neck portion 24. Additionally, a
second gasket or 0-
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.
[0082] 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.
[0083] 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 shown in Fig. 15, frustoconical
section 28 may have
an internal bore passage 230 formed through the upper end thereof. A threaded
sealing
21
CA 02776713 2012-05-15
element, such as bolt 220, is provided for selective and releasable engagement
with passage
230 to seal the upper open portion of the frustoconical section 28 from
contamination.
[0084] The alternative embodiment illustrated in Fig. 17 is similar to that of
Fig. 16, in
that the clutch cup of previous embodiments is replaced by an inner wedge or
pinion shaft
400, which includes an upper, threaded neck portion 402, a frustoconical
section 404 adjacent
the threaded neck portion 402, and an increased diameter section 406, which is
formed on a
lower end of frustoconical section 404 and extends downwardly therefrom. As in
the
previous embodiments, the upper threaded neck portion 402 includes a central
threaded
portion, and smooth, or non-threaded, upper and lower portions disposed above
and below the
threaded portion. The increased diameter section 406, as shown, has a diameter
greater than
that of the threaded neck portion 402.
[0085] A lower section 408 is formed adjacent a lower end of the increased
diameter
section 406, as shown, the lower section 408 preferably having a diameter less
than the
diameter of the increased diameter section 406, but greater than the diameter
of the threaded
neck portion 402. A gasket or O-ring 410 is mounted annularly about the lower
section 408.
The pinion shaft or inner wedge 400 is preferably formed from a relatively
soft material, such
as bronze, allowing for the elimination of the bronze clutch cup of previous
embodiments. As
shown in Fig. 18, a central passage 412 (shown in phantom) is formed through
the inner
wedge 400, allowing the inner wedge 400 to be mounted on one side of the
driveline or drive
shaft 448.
[0086] An outer wedge or housing 414 is further provided, the housing 414
having an
upper portion 416, a lower portion 418, and a central passage 420 formed
therethrough for
receiving the inner wedge 400 (as best shown in Fig. 18). The upper portion
416 is mounted
22
CA 02776713 2012-05-15
about the lower end of threaded portion 402, and the lower portion 418 of the
outer wedge
housing 414 covers the frustoconical section 404. As shown in Fig. 18, the
increased
diameter portion 406 and the lower portion 408 project outwardly from the
lower end of the
housing 414. As shown in Fig. 19, the housing 414 preferably is substantially
hexagonal. As
in the previous embodiments, the inner wedge 400 preferably is substantially
circular when
viewed from above, including the threaded section 402, the frustoconical
portion 404, the
increased diameter portion 406, and the lower section 408. Similarly, the
ancillary elements,
such as the washers and thrust bearing, all have circular cross-sectional
contours, and only the
outer wedge or housing 414 has a hexagonal contour. The outer wedge 414 is
preferably
formed from relatively hard stainless steel or the like, and the hexagonal
shape allows the
outer wedge 414 to fit within a cavity of the other side of the driveline.
When the clutch slips,
the outer wedge 414 will begin to spin only when sufficient torque is applied
thereto. Fig. 20
illustrates the assembled housing and pinion shaft (and associated components,
described in
detail below) seated within a cavity 444 of the driveline 446 of the clutch.
[0087] A thrust bearing 424 (similar to thrust bearing 74 of Fig. 16) is
sandwiched
between a pair of thrust washers 422, as shown, and the bearing 424 and the
washers 422 are
mounted about the upper portion 416 of the outer wedge housing 414 and the
neck portion
402. The thrust bearing 424 aids in preventing locknut 426 from loosening and
provides
enhanced release on the clutch. A pair of spring washers or disc springs 428,
such as
Belleville spring washers, are mounted on top of the upper thrust washer 422
(similar to disc
springs 270 of Fig. 16), and are also disposed about the neck portion 402. The
spring washers
428 provide spring-biasing between the inner wedge 400 and the outer wedge
414. The
locknut 426 is mounted on top of the spring washers 428, and is secured to the
threads on the
23
CA 02776713 2012-05-15
neck portion 402 by an internally threaded bore 432 formed centrally
therethrough. The
locknut 426 allows for adjustment in pressure between the spring washers 428,
the thrust
bearing 424, the inner wedge 400 and the outer wedge 414. A setscrew 430 is
mounted in the
locknut 426, allowing the locknut 426 to be further fastened to the threaded
neck portion 402.
[00881 A seal flange 434 is mounted above the locknut 426, and includes an
outer gasket
436, and an inner gasket 438 mounted about an inner passage 440 (similar to
outer gasket 320
and inner gasket 310 of Fig. 16). As shown in Fig. 20, the lower gasket 410
acts to seal the
lower portion, and the upper gaskets 436, 438 act to seal the upper portion,
thus preventing
contaminants from entering the driveline cavity 444 in the clutch and
interfering with
operation of the internal components. The seal flange 434 is preferably formed
from plastic.
[0089) Fig. 21 of the drawings is an exploded perspective view of another
embodiment of
the wedge clutch assembly, designated as wedge clutch assembly 500. The
alternative
embodiment 500 illustrated in Fig. 21 is similar to that of Figs. 17 through
20, in that the
clutch cup of previous embodiments is replaced by an inner wedge, pinion shaft
or torque
body 502 having a large diameter, cylindrical first end portion 504 and an
opposite smaller
diameter second end portion 506, the two end portions 504, 506 defining a
medial
frustoconical portion 508 therebetween. The torque body 502 defines a
concentric passage
510 extending completely therethrough from the first end portion 504 to the
second end
portion 506 for the installation of the assembly 500 on a drive shaft or other
shaft member
(not shown). The smaller diameter second end portion 506 includes an
externally threaded
area 512 disposed therearound. The threaded area 512 need not extend along the
entire length
of the smaller diameter second end portion 506, but may be formed about the
medial portion
of the second end portion 506, as shown in Fig. 21.
24
CA 02776713 2012-05-15
[00901 A slip member 514 fits over the conical portion 508 of the torque body
502. The
slip member 514 has a first end 516, an opposite second end 518, and a
frustoconical internal
passage 520 extending completely therethrough. The frustoconical shape of the
passage 520
is not shown in Fig. 21, but is substantially the same shape as that shown in
broken lines for
the frustoconical internal shape of the outer wedge or housing 414 illustrated
in Fig. 18. The
frustoconical shape of the passage 520 of the slip member 514 mates
frictionally with the
frustoconical portion 508 of the torque body 502 when the two components 502
and 514 are
assembled with one another. The tightness of the frictional fit between the
slip member 514
and the torque body 502 controls the degree of slippage therebetween. The slip
member 514
is preferably formed of an alloy of corrosion resistant, i.e., "stainless"
steel, and the torque
body 502 is preferably formed of bronze to provide the desired degree of
friction between the
two components.
[00911 The second end 518 of the slip member 514 includes a collar 522
extending
concentrically therefrom, with the collar 522 serving as an alignment and
retaining member
for the thrust bearing of the clutch assembly 500. The thrust bearing
comprises at least one,
and preferably two, bronze thrust washers 524a and a Teflon thrust washer 524b
installed
about the collar 522 of the slip member 514 and bearing against the second end
518 of the slip
member 514, the slip member 514 being disposed around the second end 506 of
the torque
body 502. While some type of rotating bearing might be used for this thrust
bearing
assembly, e.g., ball bearings, roller bearings, etc., it has been found that a
pair of bronze thrust
washers 524a sandwiching a Teflon (polytetrafluoroethylene; Teflon is a
registered
trademark of E.I. du Pont de Nemours and Company of Wilmington Delaware) ring
or thrust
washer 524b serve well as the thrust bearing means of the clutch assembly 500.
More or
CA 02776713 2012-05-15
fewer such washers 524a and/or 524b may be used, if desired. The bronze
material of which
the thrust washers 524a are made provides good frictional properties when they
bear against
the stainless steel material of the second end 518 of the slip member 514.
[0092] A compressive force is applied to the thrust washers 524a and 524b
against the
second end 518 of the slip member 514 by at least one concentric spring
disposed above the
thrust washer(s) 524a and 524b, capturing the thrust washer(s) 524a, 524b
between the
spring(s) and the second end 518 of the slip member 514. The at least one
compressive spring
preferably comprises a pair of corrosion-resistant steel Belleville washers
526, i.e., washers
having a slightly conical configuration allowing them to deform resiliently
under
compression. The resilient properties of the Belleville spring washers 526 may
be selected as
needed, and the orientation of the washers 526 relative to one another
provides for further
adjustment of the resilience of the assembly.
[0093] A retaining nut assembly threads onto the threaded portion 512 of the
second end
portion 506 of the torque body 502. The thrust washers 524a, 524b and the
compression
members 526 are all captured by the retaining nut assembly and compressed
toward the slip
member 514, the frustoconical passage 520 of the slip member 514 thereby being
compressed
against the frustoconical portion 508 of the torque body 502 by the retaining
nut assembly.
The retaining nut assembly may comprise a single corrosion-resistant steel
threaded adjuster
nut 528 that bears against the compression member(s) 526, but preferably
includes a second
corrosion resistant steel nut 530 above the adjuster nut 528 to serve as a
lock nut 530 for the
assembly. The friction between the torque body 502 and the slip member 514 may
be
adjusted by adjusting the adjuster nut 528 as required, and then tightening
the lock nut 530
26
CA 02776713 2012-05-15
tightly against the adjuster nut 528 to prevent rotation of the two nuts 528,
530 about the
threaded area 512 of the second end portion 506 of the torque body 502.
[0094] The clutch assembly 500 operates optimally and most consistently if the
assembly
is kept substantially free of contamination from foreign matter. Accordingly,
removable first
and second end caps 532 and 534 are installed over the first end 504 of the
torque body 502
and over at least the lock nut 530 of the retaining nut assembly installed
about the second end
506 of the torque body 502, respectively, thus sealing opposite ends of the
wedge clutch
assembly. Each of these two end caps 532 and 534 has a central passage
therethrough, the
passage 536 of the second end cap 534 being visible in Fig. 21. The passages
of the two end
caps 532 and 534 are dimensioned to fit closely about the drive shaft (not
shown) upon which
the clutch assembly 500 is installed. The second end cap 534 further includes
an internal 0-
ring groove 538 within its passage 536, and a resilient O-ring 540 is
installed within the
groove 538 to seal about the drive shaft. The circumferential interior corner
(not shown) of
the first end cap 532 is rounded to relieve stress concentrations, and the
corresponding
circumferential edge of the first end 504 of the torque body 502 is rounded
correspondingly
for proper fit of the first end cap 532 to the torque body 502. The two end
caps 532, 534 may
be formed of plastic for resilience and further sealing properties.
[0095] Additional O-ring grooves and O-rings are provided about the torque
body 502 to
provide additional protection from contamination. The torque body 502 includes
a
circumferential first O-ring groove 542 about the first end portion 504
thereof, and the
frustoconical portion 508 has a circumferential second O-ring groove 544 near
the first end
portion 504 and a third circumferential O-ring groove 546 near the opposite
second end
portion 506 of the torque body 502. Corresponding first through third
resilient O-rings 548,
27
CA 02776713 2012-05-15
550, and 552 are installed within the three grooves 542 through 546. The first
O-ring 548
serves to seal the gap between the first end cap 532 and the first end 504 of
the torque body
502 and the closely fitting passage (not shown) of the first end cap 532 and
the drive shaft
upon which the clutch assembly 500 is installed. The second and third O-rings
550 and 552
serve to substantially seal the mating frustoconical friction surfaces of the
torque body 502
and slip member 514 from contamination working its way therebetween.
[0096] The clutch assembly 500 is configured for installation in the propeller
hub of the
drive system of a boat or other watercraft, and serves to prevent damage to
the propeller or
drive due to excessive torque to the drive in the event the propeller contacts
an object.
Accordingly, certain components have outer peripheries configured to fit or
mate within the
conventional housing of such a drive system. The slip member 514 has a
substantially
circular outer periphery, as shown in Fig. 21, but the circular outer
periphery is broken by a
series of flats 554 distributed therearound. These flats serve to prevent the
slip member 514
from rotating within the housing of the drive system. Similarly, the first and
second end caps
532 and 534 have circular outer peripheries with flats 556 distributed
therearound, in
conformity with the interior configuration of the housing in which the clutch
assembly 500 is
installed.
[0097] 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.
28
