FIELD OF INVENTION
This invention relates to novel clutch cover assembly of a Diaphragm Spring
Clutch for reducing the clutch pedal effort. The effort remains within
acceptable limits throughout the normal operating life of the clutch.
BA~~GtXOUNDPM/ OR ART
I11 a conven~iollal manual clutch system, the clutch pedal actuates the
diaphragm spring (DSP) for disengagement (and engagement) of clutch. This
load on the diaphragm spring which is required to disengage the clutch is
called the release load. This release load is directly proportional to the engine
torque and thereby the clutch torque transmission requirement. Since clutch
transmits this torque through friction, the required normal force for carrying
this torque is applied by the pressure plate on the clutch disc. This load is
called the clamp load. Release load as mentioned above is the clamp load
:?:v~d:.d ')y the cover lever ratio. The mechanical linkages connecting the clutch
,., ,,.,,p. T. . t ... <, the c!utch pedal reduces this (release) load by a factor equal to the
~.-c.icaslee verage ratio, which has to be applied on the clutch pedal to actuate
the ciu~ch.
I Iow<:ver, with the wear of the clutch facing, the diaphragm spring changes its
position and the intrinsic characteristic of DSP which leads to increase in the
clamp load and the release load after the wear of the clutch disc. This increase
in release load is perceptible on the clutch pedal force actuation, which
bocornrs high and at peak value of release load, the corresponding pedal load
bccomes higher than the acceptable limit, leading to discomfort to the driver,
especially when marlouvering stop-start traffic conditions.
After s~bjcctive evaluation, it is established that for comfortable feeling of
ciutc;l pedal, the peak load of pedal actuation should not exceed 100N. This
requirement is met through several ways in different segment of vehicles. In
uT p, t::rquc cnginc:;, where increase in release load is sufficiently high with
tlriit wear of clutch, "Self Adjusting Clutch" technology (which keeps the release
load constant throughout the wear limit of clutch) is used, thereby keeping the
pedal load within acceptable limits.
Thc advantage of using SAT is more than offset by the high initial cost because
of usage of a ratched wheel, a worm screw, ramps and a spring accumulator of
cliergy. This system functions very efficiently and keeps the release load
<:onstan: througho~t the working clutch life and is especially useful for very
k ~ g hto rque engines where a small percent increase in release load may bring
. rn ,, + L. . <, s~bsecjuen: pedal load to discomforting levels. But applying this
: r : : ~ ~ : : ) , c ~fgoyr low ro medium torque engines would be infeasible in terms of
cost. Besides, the increase in clamp load (and release load, pedal load) with
wear of clutch for these (low torque) engine types isn't so high to justify usage
of SA'I'.
However, the Assist Spring Technology discussed hereinabove efficiently takes
up increase in release load to bring down pedal effort with cost effectiveness as
comparcd to SAT.
'!'he dis:rdvantages associated with Self Adjusting Technology (SAT) are as
- .. it it^:^^.^. :\.:ii., 3 .
IJsa'ule for only higll torque engines
Construction is corriplex, with large no. of child parts Expensive
i !o~rcvcr.r, eference may be made to the following prior arts:
0 6 DEC 2013
Thc invcntion relates to a friction energy accumulation clutch at an idle speed.
A bearing is arranged on a crank shaft, a flywheel is provided with a plurality of
rotating magnets, a short shaft is matched with the bearing, and a driven shaft
is provided with a convex groove which is matched with a concave groove on a
driven plate capable 'of sliding along the convex groove in a transverse
ciirect~ori; ; the driven plate is provided with spoke ribs, a lead wire is winded
araund the spoke ribs in a transverse direction, led out through a lead slot on
:! slippa4e rod, and connected with a wiring terminal, a friction lining is fixed
..r- trc ling surface of the driven plate, a pressure plate is fixedly connected
\irltn a sliding sleeve and provided with a plurality of slippage rods which are
matched with a plurality of slippage holes on a clutch cover, and a spring is
fixed between the pressure plate and the clutch cover by a spring plunger. The
clutcl~c an easily realize energy transformation and has low cost, thereby being
capablc of effectively recycling large percentage of energy consumption of
vt:hicles running at idle speed, improving the fuel utilization ratio of an entire
car and reducing the environment pollution of the car.
;:i-lc-t;i)ri ciiltch for use in a drive train having a pressure plate which is
rotatiorlally fixed with respect to a housing but which can be displaced axially
to a lirnited degree, wherein at least one disc spring is provided between the
houslng and the pressure plate, which disc spring acts on the pressure plate in
thc axial direction, and the friction clutch also has a readjustment device
which is effective between the housing and the disc spring and which ensures
at least partial cornpcnsation of at least the friction lining wear of a clutch plate
sir:. :cl: Ir teracts with the pressure plate when the friction clutch is mounted in
ORIGINAL
-5-
the drive train, wherein the disc spring can pivot with respect to an annular
support which is borne by the housing, and force is applied to said disc spring
axially in the direction of this support via spring means, wherein the spring
rricarls tzomprise aL least leaf-spring-like means, a disc-spring-like sensor
spring and at least one additional spring means.
0 6 OEC ?nfl
'i'hr: ir1vc:ntion relatcs to the technical field of automobiles, in particular to a
i'rictiori clutch for an automobile. In the friction clutch, a drive part is
composed of a flywheel, a press disc and a clutch cover, a driven part is
composcd of a driven disc friction plate, a driven disc and a driven shaft, a
cornpaction device is composed of a press spring, a control mechanism is
composcd of a release lever, a release shift fork, a pedal, a pull rod, a pull rod
adjust.ing fork, a return spring, a release bearing and a first return spring, the
rnidd'ic part of the release lever is supported on a fulcrum of the clutch cover.
'I'hc fric~.ionc lutch is simple in structure and is difficult to be abraded during
%. . .-, ,?,,.$,, . ,. < .,) : zpplicatior~, the service time of the clutch is increased, the
m:iinrcnancc rate is reduced, and economic benefit is brought.
/\ diaphragm spring assembly is provided that makes it possible to use the
same engagement member that is used in a structure with one diaphragm
spring, in a structure with two diaphragm springs disposed axially next to each
other. The diaphragm spring assembly is supported by a clutch cover and.
urges ti pressure plate. The diaphragm spring assembly includes a first
tii,ipi.,r;igrr: spring arid a second diaphragm spring. The first diaphragm spring
: i-;:..iidc:, ai.; anri ;rlai- first elastic portion and a plurality of first lever portions
. . ::xlcr;dir:g from thc first elastic portion in a radially inner direction. The second
diaphragm spring includes an annular second elastic portion disposed on the
ORIGINAL
semc rarlial position as the first elastic member, and a plurality of second lever
;,-~::rti::ns cx~cl-lding from said second elastic portion in a radially inner
dircctiori. The second lever portions are shorter than the first lever portions.
OBJECTS OF THE INVENTION 0 6 OEC 10'3
'I'he primary object of the present invention is to provide novel clutch cover
assembly of a Diaphragm Spring Clutch for reducing the clutch pedal effort
which overcomes disadvantages associated with the prior art(s).
Arlotfier object of the present invention is to provide novel clutch cover
assembly of a Diaphragm Spring Clutch for reducing the clutch pedal effort
which is ef'ficicnt and reliable.
' -1 . ,,,,:,(-.: ob,cct of' tnc present invention is to provide novel clutch cover
assembly of a Diaphragm Spring Clutch for reducing the clutch pedal effort
which is simple in construction and cost effective.
Still further object of the present invention is to provide novel clutch cover
assembly of a Diaphragm Spring Clutch for reducing the clutch pedal effort
which is applicable for low to medium torque engine.
SUMFdIARY OF THE-INVENTION
I > r.c,,. . , . - +,,. , T , ~ .., t , (, . !nis invtmtion, there is provided novel clutch cover assembly of a
*;:ap::r:igm Spring Clutch for reducing the clutch pedal effort comprising a
hclical compression spring provided between clutch cover and pressure plate,
whercin said spring elongates so as to provide force against the clamp load and
release ioad.
BRIEF I)ESCRIPTION OF THE ACCOMPANYING DRAWINGS
0 6 DEC ?0\3
Ili'urther objects and advantages of this invention will be more apparent from
the ensuing description when read in conjunction with the accompanying
drawings and wherein:
i+'ig;. I :;bows: novcl clutch cover assembly of a diaphragm spring cllltch
accordir:g to the present invention.
;'ig. 2 s'riows: clamping load (C) vs deflection (D) curve.
Fig. 3 sfiows: rcleasc load (I?) vs release stroke (S) curve.
DETAIL DESCRIYTION OF THE INVENTION WITH REFERENCE TO THE
ACCOMPANYING DRAWINGS:-
'l'ilc prc:serit invention discloses novel clutch cover assembly of a Diaphragm
Spririg Clutch for reducing the clutch pedal effort. Now, reference may be made
io fig. 1 , whcrcin a helical compression spring (1) is provided between clutch
cover (2) and pressure plate (3). The pressure plate may be provided with an
. .;?d;t.;:,;al lug (4) for accommodating the spring (1).
'~'hc sprlng can be cylindrical or conical according to the requirement, which is
initially at its free length.
With wear of the clutch, said spring elongates so as to provide force against the
clamp load and release load.
0 6 DEC 20\3
'I'he conventional clutch is not provided with the spring, wherein only strap
platcs are provided which lift the pressure plate during clutch disengagement
:::;:1 :.1::7,1ccl the clutch cover with the pressure plate.
!. ': itc spring is such that it takes its free length in set condition so that the
clamp load is not reduced due to spring action.
2. With subsequent wear of ~lutch, the spring becomes active with the
movement of the pressure plate away from the clutch cover and provides
force against the clamp load. This causes the clamp load to reduce along
the entire wear travel of the clutch.
3. With reduction in clamp load, the release load too reduces. This decrease
i i i release load (as compared to release load corresponding to max. clamp
load of current design clutch) is sufficient to bring the pedal load within
ac ccptablc limits.
4. Sincc the increase in clamp load isn't linear, either a helical spring with
v~ryingp itch or a conical helical compression spring can be provided to
have the spring force sufficiently high with change in PP position to take
care of non-linear nature of the clamp load.
5. Additional lugs may be required to be provided on the casted PP to
accommodate the spring, besides the strap plate. Alternatively, the
spring can be mounted at the same location of PP itself (since other end
of strap is located at a different axial location on the clutch cover).
5. Uarir~gt he PP lift 'at the set condition', there is a tendency of the springs
to counter action of strap plate. Subsequently, the springs assist the
s: -ay: ~!atcac tior, and I'P lift.
ORIGINAL
Zg';igi~j8 t ? & & ~ ~otf? th~e invention over prior art:
0 6 OEC 20Y3
'1. \ c: : c l ~ t c hp rdal load is reduced for the working range of clutch disc with cost
cffcctivcness.
The clamp load curve of the clutch would follow the curve as shown in fig. 2, in
r:omparison to the existing invention, wherein present invention is shown in
clotted Ilnes. Release load curve in fig. 3 is also shown with the current and
modified design. Fig. 2 indicates the following:-
- Clamp load curve (with assist) (I),
CIarrip load curve (normal) (2))
Sc t 13int (3),
Wcar Point (4),
Wear in (5) and
st.t (6).
Figure 3 indicates the following:-
- lo,,id curve (wcar) with assist (I),
io,id curve (new) with assist (2))
load rilrvc (new) (normal) (3))
!:;,ld curve (wcar) normal (4),
w:)rn condition (5),
(:: mr cc~ndi~lo{n6 ),
- curve shift (due to clutch wear) (7))
- variation with assist (low) (8) and
variation without assist (large) (9).
8:~se_qgtionsw ith reference to fig. 2 and 3
As shown, the value of clamp load for assist spring follows a deviated, lower
curvc with reference to the normal one, in essence showing the spring force
coming into action with start of clutch wear.
!'he :%orresponding release load curve comparison is also known. For the
normal (i.e. without assist) curve, the load increase b/w new and worn-out
,.1\11cr: r-ondition is significant, which translates to a corresponding surge in
c'itlicrl pedal load too, which is perceptibly disconcerting to the driver. However,
,i car '11 : scXen that sirriilar increase in release load (and hence the pedal load)
with (:lutch wear may be significantly lesser in case of assist spring technology,
with optimal use of assist spring specifications.
This dcsign leads to reduction in corresponding release load and pedal load,
thcrcby mitigating the increase in pedal load with clutch wear and providing
optimizing pedal effort over entire clutch wear range.
:$'igt?r:. 7 above shows that the wear point in assist spring corresponds to a
i{wcr clamp load as compared to normal one. Lower clamp load refers to
2 ( ~LA(l-03 torquc carrying capacity of clutch. However, the standard factor of
safety ;'or clanlp load values combined with lower chances of abuse load in
~,ssscll,r,:r cars may more than compensate the decreased TCC of clutch with
thc prcsent invention.
'I'hus, the present invention reduces the clutch pedal effort within the
acceptable limits throughout the normal operating life of the clutch.
ii is LO be rloted that the present invention is susceptible to modifications,
iicrapi.aiions and changes by those skilled in the art. Such variant embodiments
(:i-nployiilg inc conccpts and features of this invention are intended to be within
thc scope of the present invention, which is further set forth under the following claims:-

WE CLAIMS:-
1. Novel clutch cover assembly of a Diaphragm Spring Clutch for reducing
: r.c: cltitch pcdal effort comprising a helical compression spring provided
1;t tween clutch cover and pressure plate, wherein said spring elongates
sc: as to provide force against the clamp load and release load.
2. Novel clutch cover assembly of a Diaphragm Spring Clutch as claimed in
claim 1, wherein the pressure plate may be provided with an additional
lug for accommodating the spring.
3 . Novei clutch cover assembly of a Diaphragm Spring Clutch as claimed in
cl.iim 1 or 2, wherein the spring can be cylindrical or conical according to
! ..-:: ri.cluircrnttnt, which is initially at its free length.
4. Novel clutch cover assembly of a Diaphragm Spring Clutch as claimed in
ariy of the preceding claims, wherein the helical spring with varying pitch
or coriical helical compression spring is provided having the spring force
s~~fficientlhyig h with change in the position of PP to take care of nonlinear
nature of the clamp load.
5. Novci clurch cover assembly of a Diaphragm Spring Clutch as claimed in
ally of the pryceding claims, wherein the spring can be mounted directly
:;i t k i r prcssurt: plate.
6. Novel clutch cover assembly of a Diaphragm Spring Clutch as claimed in
arzy of the preceding claims, is associated with the salient features such
as herein described.
7. Novel clutch cover assembly of a Diaphragm Spring Clutch as claimed in
ar;y of thc preceding claims, is associated with the observations such as
hrrein dcscribed.
3. hovel cluich cover assembly of a Diaphragm Spring Clutch for reducing
t:;c clutch pcdal effort substantially as herein described with reference to
the accompanying drawings.