Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02768243 2012-02-16
FRICTION CLUTCH SYSTEM
FIELD OF THE INVENTION
100011 This invention relates generally to a friction clutch system for
mechanically
coupling a power source to a driven system of a vehicle.
BACKGROUND OF THE INVENTION
100021 As shown in FIGURE 1, one conventional type of friction clutch system
10
may be found in an automobile for engaging, disengaging and transmitting
torque from the
engine 12 (i.e., power source) to a transmission 14 (i.e., driven system). By
way of example,
the conventional automotive friction clutch system 10 includes a thrust or
pressure plate 16
mounted within a clutch housing 18 so that the thrust plate 16 cannot rotate
within the
housing 18, but can move axially within the clutch housing. The housing 18 is
mounted to a
counterthrust plate 20. Being weighted, the counterthrust plate is also
commonly used as a
flywheel as well. The flywheel 20 is mounted to and driven by the power source
12, which
may take the form of an internal combustion engine, an electric motor, etc.
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[0003] The pressure plate 16 may be biased or pressed toward the flywheel 20
by
one or more partially compressed Belleville springs, (diaphragms), or coil
springs (not
shown) and may or may not also employ centrifugal clamping force assist (in
the form of bob
weights, not shown) all of which can be mounted within the housing 18. The
assembled
combination of the clutch housing 18, the pressure plate 16, and the
diaphragm/spring is
generally referred to as a pressure plate assembly 22 within the automotive
industry.
[0004] A friction disc assembly 24 is located between the flywheel 20 and the
pressure plate assembly 22. The friction disc assembly 24 includes, in the
illustrated
example, a floater disc 26 sandwiched between two friction discs 28. The
friction discs 28
include friction facings or linings 30, a carrier plate 32 and a splined hub
34. The friction
facings 30 bonded or otherwise, are mechanically connected to the carrier
plate 32. The
carrier plates 32 are coupled by the splined hub 34, which takes the form of
an internally
splined hub, to an externally splined shaft 36 of the driven member 14.
[0005] In FIGURE 2, the like components retain the same reference numerals,
but
the friction clutch system 10 includes a different friction disc assembly 40.
As illustrated, the
friction disc assembly 40 includes a floater disc 42 sandwiched between two
friction
discs 44, both having multiple, radially located damper springs 46 for the
purpose of
smoothing clutch engagement and isolating engine vibrations from the
transmission 14 and
driveline (not shown). The damper springs 46 are positioned in a sprung hub
assembly 48
that extends axially.
[0006] For greater torque capacity and improved heat dissipation, a friction
clutch
system may incorporate multiple friction discs mounted between the pressure
plate assembly
and the flywheel. For multi-plate clutch designs, the floater or floater plate
may be mounted
to and driven by the flywheel, with a floater being located between adjacent
pair of friction
discs. The pressure plate assembly, flywheel and floater also serve as
friction surfaces for the
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friction discs. Because each friction disc assembly typically has two friction
surfaces, a two
disc clutch will have four friction surfaces, a three disc clutch will have
six friction surfaces,
and so on.
[0007] The torque capacity of a friction clutch system is defined as the
maximum
amount of torque that can be transferred through the system while in its fully
engaged state.
Once the clutch torque capacity has been exceeded, torque can be lost through
the
unintentional slipping effect caused between the friction surfaces of the
friction clutch system
components.
[0008] The conventional clutch system of FIGURE 1 includes two solid hubs,
each
with internal splines for engaging the shaft of the transmission, but without
any damper
springs to reduce the spatial envelop and provide a low rotating weight.
However, the lack of
damper springs to smooth clutch engagement and isolate engine vibrations can,
at least
eventually, have a detrimental effect on driveline components. In addition,
clutch
performance and drive-ability of the vehicle may be diminished.
[0009] The conventional, multiple disc clutch system of FIGURE 2 with the two
sprung hub assemblies, both internally splined for engaging the shaft of the
transmission may
help with isolating engine vibrations, but require a greater spatial envelope
and increase the
rotating weight of the system. Current space constraints in various vehicles
would not
provide room for such an arrangement. Consequently, both conventional systems
may be
undesirable for use as a high-performance clutch system
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SUMMARY OF THE INVENTION
[0010]
[0011] In one aspect of the invention, there is described a friction clutch
system
comprising: a flywheel defining an axis of rotation and having a plurality of
pins protruding
therefrom; first and second pressure plates; a floater having a front face and
a rear face and
defining a plurality of pin receivers extending through the floater from the
front face to the
rear face, the front face interfacing with the first pressure plate and the
rear face interfacing
with the second pressure plate, each pin receiver having a pin of the
plurality of pins
slidingly positioned therein, the floater having a plurality of engagement
surfaces each
extending from the front face to the rear face, the plurality of engagement
surfaces each
being parallel to the axis of rotation from the front face to the rear face;
and a plurality of
coupling assemblies each secured to the flywheel and biased into engagement
with one of the
engagement surfaces of the plurality of surfaces of the floater; wherein each
coupling
assembly includes a spring-loaded mechanism arranged to exert a radially
inward biasing
force onto one of the engagement surfaces of the plurality of engagement
surfaces of the
floater.
[0012] In another aspect of the invention, there is described a method for
coupling a
floater to a flywheel, the method comprising: positioning the floater adjacent
to the flywheel,
wherein positioning the floater includes arranging the floater to have a
radial gap relative to a
protrusion extending from the flywheel; attaching a coupling assembly to the
flywheel; and
orienting the coupling assembly to absorb kinetic energy of the floater along
at least one
radial line extending from a center point of the floater, wherein absorption
of the kinetic
energy permits at least some radial displacement of the floater relative to
the flywheel;
wherein the coupling assembly includes a plurality of sleeves coupled to the
flywheel and
defining an opening facing inward toward the floater; a plurality of springs,
each spring of
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the plurality of springs being positioned within a sleeve of the plurality of
sleeves; a plurality
of engagement members slidably engaging the sleeves and protruding out of the
sleeves into
engagement with the floater.
[0013] In yet another aspect of the invention, there is also described a
friction clutch
system comprising: a flywheel defining an axis of rotation and having a
plurality of pins
protruding therefrom; first and second pressure plates; a floater having a
front face and a rear
face and defining a plurality of pin receivers extending through the floater
from the front face
to the rear face, the front face interfacing with the first pressure plate and
the rear face
interfacing with the second pressure plate, each pin receiver having a pin of
the plurality of
pins slidingly positioned therein, the floater having a plurality of
engagement surfaces each
extending from the front face to the rear face, the plurality of engagement
surfaces each
being parallel to the axis of rotation from the front face to the rear face;
and a plurality of
coupling assemblies each secured to the flywheel and biased into engagement
with one of the
engagement surfaces of the plurality of surfaces of the floater, wherein the
plurality of
coupling assemblies each include: a sleeve coupled to the flywheel and
defining an opening
facing inward toward the floater; a plurality of springs, each spring of the
plurality of springs
being positioned within a sleeve of the plurality of sleeves; a plurality of
engagement
members slidably engaging the sleeves and protruding out of the sleeves into
engagement
with the floater.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Preferred and alternative embodiments of the present invention are
described
in detail below with reference to the following drawings.
[0015] FIGURE 1 is an exploded, schematic view of a prior-art friction clutch
system
having friction disc assemblies each with solid hubs coupled to a splincd
shaft of a driven
member;
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[0016] FIGURE 2 is an exploded, schematic view of a prior-art friction clutch
system
having friction disc assemblies each with damping springs located in hubs
coupled to a
splined shaft of a driven member;
[0017] FIGURE 3A is an exploded, schematic view of a friction clutch system
having
a first friction disc assembly with protuberances to directly engage a second
friction disc
assembly according to an embodiment of the present invention;
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[0018] FIGURE 3B is schematic, side elevational view of the first friction
disc of
FIGURE 3A with protuberances according to an embodiment of the present
invention;
[0019] FIGURE 3C is schematic, side elevational view of the second friction
disc of
FIGURE 3A with openings according to an embodiment of the present invention;
[0020] FIGURE 4 is a perspective, exploded, partially cut-away view of a
friction
clutch system having a first friction disc assembly with protuberances to
directly engage a
second friction disc assembly according to an embodiment of the present
invention;
[0021] FIGURE 5 is a an exploded, schematic view of a friction clutch system
having
a first friction disc assembly positioned adjacent to a driven member (e.g.,
pressure plate
assembly) and a second friction disc assembly positioned adjacent to a power
source
(e.g., flywheel) according to another embodiment of the present invention;
[0022] FIGURE 6A is a top, plan view of a friction clutch system having a
floater
resiliently coupled to a flywheel with a plurality of resilient coupling
assemblies according to
an embodiment of the present invention;
[0023] FIGURE 6B is a top, plan view of one of the resilient a spring portion
and clip
portion from one of the resilient coupling assemblies of FIGURE 6A;
[0024] FIGURE 6C is a top, plan view of a spring portion from one of the
resilient
coupling assemblies of FIGURE 6A;
[0025] FIGURE 7 is a schematic side view of the friction clutch system of
FIGURE 6A;
[0026] FIGURES 8A, 8C and 9 are perspective views of a friction clutch system
having spring-loaded members mounted to the clutch pressure plate according to
another
embodiment of the present invention; and
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[0027] FIGURES 8B, 8D, 8E, 8F and 8G are perspective views of a friction
clutch
system having spring-loaded detent members mounted to the flywheel according
to another
embodiment of the present invention.
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] The present invention generally relates, but is not limited, to
friction clutch
system for mechanically coupling a power source to a driven system of a
vehicle. In at least
one embodiment, the present invention combines a spring-damped, splined hub
with one or
more secondary friction discs. The hub includes axially extending
protuberances that engage
radial slots located in the secondary friction disc. Advantageously, the
friction clutch system
described herein may allow for torsional vibration damping while reducing the
rotational
mass of the system. Further, the friction clutch system may provide a more
compact and
simplified installation.
[0029] FIGURE 3A shows an exploded, schematic view of a friction clutch
system 100 for engaging, disengaging and transmitting torque from a power
source 102 (e.g.,
engine) to a driven member 104 (e.g., transmission). Similar to the
conventional friction
clutch systems described above, the illustrated friction clutch system 100
includes a pressure
plate assembly 106 comprising a pressure plate 108 mounted within a clutch
housing 110,
which in turn is mounted to a counterthrust plate or flywheel 112.
[0030] In the illustrated embodiment, the pressure plate assembly 106 includes
a
spring or springs that provide the primary engagement force to a friction disc
assembly 114,
which may include multiple (two or more) friction discs 116, 118 with a
floater plate 120
located therebetween. The floater plate 120 may take the form of the floater
plates previously
described.
[0031] Of the two illustrated friction discs 116, 118, only first disc 116
includes a hub
assembly 122 mounted to a driven shaft 124. The second disc 118 does not have
a hub
assembly (e.g., sprung hub) and is not mounted to the driven shaft 124, but
instead engages
the first disc 116 as will be described in detail below. Such a configuration
may
advantageously provide a lighter weight system having a lower rotational
inertia while also
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being more spatially compact than previous systems in which each friction disc
included its
own hub assembly independently splined to the driven shaft. The space
requirements are
reduced due to having fewer sprung splined hub assemblies than friction discs.
One of the
drawbacks of the conventional assembly shown in FIGURE 2 was that the amount
of space
required to have a sprung hub on each friction disc exceeded the allowable
design spatial
envelope between the pressure plate assembly and flywheel. Thus, to fit such
an assembly the
springs in the hub assembly would have to be made quite small, making them
more difficult
to install, harder to retain and less robust in view of the spring forces
needed. Another
possible advantage of the friction clutch system 100 is that it may replace
stock clutch
systems within the space envelope provided for the stock clutch system.
100321 Referring now to FIGURES 3 and 4, the first disc 116 includes the hub
assembly 122 and friction facing and/or a plurality of friction pads 126
mounted
circumferentially onto a disc body 128. The hub assembly 122 includes an
internal splined
portion 130, a plurality of damping springs 132, and a plurality of
protuberances 134
extending from a hub assembly cover 136. The damping springs 132 may take the
form of
torsional damping springs. The protuberances 134 may take the form of pins or
dowels,
which may be cylindrical or have another type of cross-sectional shape. The
protuberances 134 extend in an axial direction as indicated by arrow 138
(FIGURE 3A).
100331 The second disc 118 includes a friction facing and/or a plurality of
friction
pads 140 coupled to a central member 142. A plurality of openings 144 are
machined or
otherwise formed into the central member 142. The openings 144 may take the
form of radial
slots or notches extending from an inner edge 146 of the central member 142.
In addition, the
openings 144 are configured to receivably and directly engage the
protuberances 134 of the
first disc 116. This engagement prevents the discs 116, 118 from rotating
relative to one
another, but will permit independent axial movement of the secondary friction
disc(s) within
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the given design range. As best seen in FIGURE 4, the openings 144 preferably
have a shape
that complementarily corresponds to the cross-sectional shape of the
protuberances 134. For
example, if the protuberances 134 are cylindrical then the openings will be
circular as well.
Alternatively radial slots could receive protuberances of various
configurations. Further the
openings 144 are sized and aligned to accurately receive the protuberances
134.
100341 FIGURE 5 shows a friction clutch system 200 in which a first disc 202
with a
hub assembly 204 and protuberances 206 is positioned adjacent to a pressure
plate
assembly 208. A second disc 210 with openings (not shown) to receive the
protuberances 206 is positioned adjacent to a flywheel 212. In comparing
FIGURE 5 to
FIGURE 3, the locations of the first and second discs have been switched.
Consequently, the
first disc 202 may be on the driven side proximate the driven member 214
(e.g.,
transmission) while the second disc 210 may be on the driving or power side
proximate the
power source 216 (e.g., engine).
100351 FIGURES 6A and 6B show a friction clutch system 300 with a floater 302
resiliently coupled to a flywheel 304 by means of drive pins 305 or lugs
attached to the
flywheel 304. This engagement between the flywheel 304 and the floater 302
prevents
independent rotation relative to one another, but will allow independent axial
movement of
the floater plate 302 relative to the flywheel 304 In the illustrated
embodiment, the resilient
coupling is achieved with a resilient coupling assembly 306, which as best
shown in
FIGURE 6B takes the form of a leaf spring 308 fixed to a clip 310. The leaf
spring 308 may
include a central arcuate portion 312 fixed to the clip 310. Symmetric arms
314 extend
respectively from the central arcuate portion 312. Both arms 314 include a
contact
surface 316 for contacting the floater 302 along a radial line of action 315
relative to a center
point 317 of the floater 302. However, the resilient coupling assembly 306 may
take other
forms such as a compression spring or a spring-loaded detent. The free ends of
these springs
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or detents 308 may be weighted or manufactured in a manner that will allow a
centrifugal
force, generally directed radially outward as shown by arrow 319, to overcome
or negate the
spring force, generally directed radially inward as shown by directional arrow
321, acting
upon the floater 302. This design allows for quiet clutch operation at low
engine revolutions
per minute (RPM) while improving high RPM gear changes.
[0036] FIGURE 6C shows the leaf spring 308 with a number of reference
dimensions
to generally indicate that the leaf spring 308 may be designed for a variety
of situations to
provide a stiffer or softer spring rate. By way of example, a shackle angle
318 that
determines the angle of the eyes 320 relative to a datum line 322 may be
varied to increase or
decrease spring rate. A vertical line 324 indicates a ninety degree (90 )
shackle angle. In
addition, a radius 326 of the central arcuate portion 312 may be modified to
change the
spring rate of the leaf spring 308. In the illustrated embodiment, the radius
defines a
reference circle 328. However, it is appreciated that the central arcuate
portion 312 may be
non-circular, for example parabolic or have some other complex curvature.
[0037] Referring back to FIGURE 6A, the friction clutch system 300 includes
three
resilient coupling assemblies 306, which corresponds to six contact locations
because each
assembly 306 includes two arms 314 (FIGURE 6B). However, it is appreciated
that a fewer
or greater number of resilient coupling assemblies 306 may be employed
depending on the
size, loading, and other aspects of the friction clutch system 300. The
resilient coupling
assemblies 306 preferably in combination with gaps 330 permit the floater 302
to operate
relative to the flywheel 304 while minimizing, if not eliminating, audible
sounds that would
ordinarily come from the floater 302 vibrating or "rattling" relative to the
flywheel 304.
[0038] FIGURE 7 schematically shows the floater 302 coupled to the flywheel
304
using the resilient coupling assembly 306. The clip 310 takes the form of a
bent metal
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clip mechanically attached to the flywheel 304 with a fastener 322. The spring
force of the
clip 310 is generally directed as indicated by arrow 334.
[0039] FIGURES 8A, 8C and 9 show another embodiment of a friction clutch
system 400 having a floater 402 resiliently coupled to a pressure plate
assembly 404 with a
resilient coupling assembly 406. In the illustrated embodiment, the assembly
406 takes the
form of a spring-loaded mechanism that is compression loaded between the
floater 402 and
the pressure plate assembly 404. The spring-loaded mechanism 406 is oriented
along a radial
line of action 408 extending from a central point 410 of the floater 402 or
pressure plate 404
toward the spring-loaded mechanism 406. Alternatively stated, the spring-
loaded
mechanism 406 is attached to the pressure plate 404 and oriented to absorb
kinetic energy
from the floater 402 in a radial direction 408, and in which a spring force of
the
mechanism 406 is directed radially inward as indicated by arrow 412 to react a
centrifugal
force directed radially outward as indicated by arrow 414. In the illustrated
embodiment, the
assembly 406 takes the form of a semi-spherical member in contact engagement
with a pin as
best shown in FIGURE 8C.
10040] FIGURE 8B and 8D-8F show the friction clutch system 400 with the
flywheel 404engaged with the floater 402 using a detent mechanism 406. In the
illustrated
embodiment, the detent mechanism 406 is adjustably received in a boss or lug
416 coupled to
the flywheel 404. The mechanism 406 includes an externally threaded body 418
that permits
adjustment relative to the boss 416 and an end cap 420 to secure the mechanism
406 once
adequately adjusted.
[0041] Referring specifically to FIGURES 8E-8G, the detent mechanism 406
includes the threaded body 418 coupled to a detent plunger 422. A collar 424
may be coupled
to an end portion of the threaded body 418 to provide a tapered transition
from the threaded
body 418 to the detent plunger 422.
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[0042] Referring specifically to FIGURES 8F and 8G, the mechanism 406 includes
a
biasing member 426 located within the threaded body 418. The biasing member
426 may
take the form of a coil or compression spring having one end portion seated
against a back
wall of the threaded body 418 and an opposite end portion seated against the
plunger 422.
FIGURE 8F shows the biasing member 426 in an extended position such that a tip
of the
plunger 422 has been moved away from the threaded body 418; whereas FIGURE 8G
shows
the biasing member in a compressed position.
[0043] In the illustrated embodiments, the resilient coupling between the
flywheel 404 and the floater 402 is achieved with a detent spring-loaded
mechanism 406.
FIGURE 8B and 8D best show the detent spring-loaded mechanism 406 is mounted
to the
flywheel 404 by threaded means within machined or otherwise permanently
attached
mounting lugs 416.
[0044] FIGURE 8E, 8F and 8G best shows the body of the detent spring-loaded
mechanism 424 contains external threads 418 in which directly engage the
internal threads
(not shown) contained within the flywheel mounting lug 416 and allows for
threaded lock
nut 420 to prevent unintended movement of the detent mechanism 406 in
relationship to the
mounting lug 416. As best shown in FIGURES 8F and 8G the spring-loaded detent
pin 422 is
allowed liner movement within the mechanism body 424 by compressing detent
spring 426.
[0045] FIGURE 8F is a cut-a-way view that shows the detent spring 426 fully
extended within the detent body 424. FIGURE 80 is a cut-a-way view that shows
the detent
spring 426 partially compressed within the detent body 424. By means of the
external body
threads 418 (FIGURE 8E) and internal threads (not shown) contained within the
flywheel
detent mounting lugs 416 allows for varying the amount of spring compression
thus allowing
easy spring force adjustment during manufacture and/or by the end user for
individual
application optimization. Referring back to FIGURE 8B, the detent pins 422
(shown in
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FIGURES 8E, 8F and 8G) can be weighted or manufactured in a manner such that
will allow
centrifugal force, generally directed outward as shown by arrow 414, to
overcome or negate
the spring force as applied by detent spring 426 (shown in FIGURES SF and 8G),
force
applied generally directed as shown by directional arrow 412 and acting
directly upon the
floater 402. This design also allows for quiet clutch operation at low engine
revolutions per
minute (RPM) while improving high RPM gear changes.
[0046] While the preferred embodiments of the invention have been illustrated
and
described, as noted above, many changes can be made without departing from the
spirit and
scope of the invention. Accordingly, the scope of the invention is not limited
by the
disclosure of the preferred embodiments. Instead, the invention should be
determined
entirely by reference to the claims that follow.
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