U.S. patent number RE37,465 [Application Number 09/146,928] was granted by the patent office on 2001-12-11 for torque transmitting and torsion damping apparatus for use in motor vehicles.
This patent grant is currently assigned to LuK Lamellen und Kupplungsbau GmbH. Invention is credited to Hans-Dieter Elison, Wolfgang Reik.
United States Patent |
RE37,465 |
Reik , et al. |
December 11, 2001 |
Torque transmitting and torsion damping apparatus for use in motor
vehicles
Abstract
A torsion damping apparatus between the crankshaft of the engine
and the input shaft of the change-speed transmission of a motor
vehicle has two flywheels one of which is driven by the crankshaft
and the other of which drives the input shaft by way of a friction
clutch which generates heat. In order to prevent the transfer of
heat from the friction clutch to the antifriction bearing between
the flywheels, which are rotatable relative to each other against
the opposition of a damper, the bearing is at least partially
surrounded by a thermal barrier of synthetic plastic, ceramic or
metallic material which prolongs the useful life of the bearing and
enhances the torsion damping action of the damper. The thermal
barrier can constitute or form part of the damper. The bearing can
be disposed radially inwardly of the location of engagement between
the clutch and the other flywheel and can be cooled by streams of
air flowing through an annulus of passages each having a first end
disposed radially inwardly of the friction surface of the other
flywheel and a larger second end in a second surface of the other
flywheel opposite the friction surface. Heat barriers in the other
flywheel can alternate with the passages in the circumferential
direction of the other flywheel.
Inventors: |
Reik; Wolfgang (Buhl,
DE), Elison; Hans-Dieter (Offenburg, DE) |
Assignee: |
LuK Lamellen und Kupplungsbau
GmbH (Buhl/Baden, DE)
|
Family
ID: |
27433140 |
Appl.
No.: |
09/146,928 |
Filed: |
September 1, 1998 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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658929 |
May 31, 1996 |
|
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973850 |
Nov 9, 1992 |
|
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283792 |
Dec 13, 1988 |
4989710 |
Feb 5, 1991 |
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132909 |
Dec 14, 1987 |
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000470 |
Jan 5, 1987 |
4727970 |
Mar 1, 1988 |
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716838 |
Mar 28, 1985 |
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Reissue of: |
616640 |
Nov 21, 1990 |
05069321 |
Dec 3, 1991 |
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Foreign Application Priority Data
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Jun 12, 1984 [DE] |
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34 21 709 |
Nov 23, 1984 [DE] |
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34 42 679 |
Apr 15, 1985 [DE] |
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35 13 449 |
Apr 16, 1985 [DE] |
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35 13 479 |
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Current U.S.
Class: |
192/70.17;
192/113.4; 192/213.22; 464/68.41 |
Current CPC
Class: |
F02B
75/06 (20130101); F16C 35/073 (20130101); F16C
35/077 (20130101); F16F 15/131 (20130101); F16F
15/13164 (20130101); F16F 15/134 (20130101); F16F
15/139 (20130101); F16F 15/1397 (20130101); F16C
33/7886 (20130101); F16C 27/066 (20130101); F16D
2013/703 (20130101); F16D 2013/706 (20130101); F16F
2222/02 (20130101); F16F 2222/025 (20130101); F16C
19/06 (20130101); F16C 2361/55 (20130101) |
Current International
Class: |
F02B
75/00 (20060101); F02B 75/06 (20060101); F16F
15/139 (20060101); F16F 15/134 (20060101); F16C
35/077 (20060101); F16C 35/073 (20060101); F16C
35/04 (20060101); F16F 15/131 (20060101); F16F
015/30 (); F16F 015/12 (); F16F 015/134 (); F16D
003/12 () |
Field of
Search: |
;192/70.17,3V,11B,213.22,113.4 ;74/574 ;464/68,66 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bonck; Rodney H.
Attorney, Agent or Firm: Darby & Darby
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
.[.This is a division of copending patent application Ser. No.
283,792 filed Dec. 13, 1988, now U.S. Pat. No. 4,989,710, granted
Feb. 5, 1991, which is a division of abandoned patent application
Ser. No. 132,909 filed Dec. 14, 1987 which is a division of Ser.
No. 000,470 filed Jan. 5, 1987, now U.S. Pat. No. 4,727,970, which
is a continuation-in-part of abandoned patent application Ser. Nos.
716,838 (filed Mar. 28, 1985), 799,006 (filed Nov. 18, 1985) and
848,732 (filed Apr. 4, 1986)..].
.Iadd.This is a division of Reissue application Ser. No.
08/658,929, filed May 31, 1996, now abandoned, which is a
continuation of Ser. No. 07/973,850, filed Nov. 9, 1992, now
abandoned, which is a Reissue of application Ser. No. 07/616,640,
filed Nov. 21, 1990, now U.S. Pat. No. 5,069,321, granted Dec. 3,
1991, which is a division of application Ser. No. 07/283,792, filed
Dec. 13, 1988, now U.S. Pat. No. 4,989,710, granted Feb. 5, 1991,
which is a division of application Ser. No. 07/132,909, filed Dec.
14, 1987, now abandoned, which is a division of application Ser.
No. 07/000,470, filed Jan. 5, 1987, now U.S. Pat. No. 4,727,970,
granted Mar. 1, 1988, which is a continuation-in-part of
application Ser. No. 06/716,838, filed Mar. 28, 1985, now
abandoned. Each of these prior applications is hereby incorporated
herein by reference, in its entirety..Iaddend.
The apparatus of the present invention constitutes an improvement
over a further development of torque transmitting, torsion damping
and similar apparatus which are disclosed in numerous pending U.S.
patent applications and granted United States Letters Patent of the
assignee. Reference may be had, for example, to commonly owned
patent applications Ser. Nos. 661,028 (filed Oct. 15, 1984), and
now U.S. Pat. No. 4,638,684, 669,658 (filed Nov. 8, 1984), and now
abandoned 669,659 (filed Nov. 8, 1984), and now abandoned 669,769
(filed Nov. 8, 1984), 669,770 (filed Nov. 8, 1984), 669,768 (filed
Nov. 8, 1984), and now abandoned 717,327 (filed Mar. 29, 1985),
706,498 (filed Feb. 28, 1985), and now U.S. Pat. No. 4,611,701
745,016 (filed Jun. 14, 1985), 801,565 (filed Nov. 25, 1985) and
now abandoned and 844,475 (filed Mar. 26, 1986).
Claims
We claim: .[.
1. Apparatus for compensating for variations of torque, especially
for fluctuations of torque which is transmitted between a
combustion engine and an input means of a transmission, comprising
at least two flywheels which are rotatable relative to each other,
one of which is connectable with the engine and the other of which
is connectable with the input means of the transmission and carries
a disengageable friction clutch; antifriction bearing means
interposed between said flywheels; a substantially disc-shaped
member non-rotatably connected with said other flywheel; and damper
means arranged to oppose rotation of said flywheels relative to
each other, said damper means at least comprising energy storing
means acting in the circumferential direction of said flywheels,
and a friction generating device which is disposed between said
flywheels, said friction generating device operating with friction
axially between said member and said one flywheel and comprising a
friction ring and a stressed energy storing element acting in the
axial direction of said flywheels..]..[.
2. The apparatus of claim 1, wherein the stressing of said energy
storing element of said friction generating device is such that
said energy storing element exerts a force having a component
acting against said other flywheel in a direction at least
substantially counter to the direction of action of force which is
to be applied to disengage the friction clutch..]..[.
3. The apparatus of claim 1, wherein said energy storing element
reacts against said antifriction bearing means..]..[.
4. The apparatus of claim 1, wherein said other flywheel has a
shoulder and said antifriction bearing means is disposed between
said shoulder and said member in a predetermined axial position
relative to said flywheels..]..[.
5. The apparatus of claim 4, wherein said antifriction baring means
comprises an inner race and an outer race surrounding said inner
race, and further comprising a thermal barrier between said
antifriction bearing means and said other flywheel, said thermal
barrier comprising heat-insulating rings each having a
substantially L-shaped cross-sectional outline and each including
an annular portion surrounding said outer race and a radially
extending portion sealingly engaging said inner race..]..[.
6. The apparatus of claim 5, wherein one of said heat-insulating
rings is adjacent said member and another of said heat-insulating
rings is adjacent said shoulder..]..[.
7. The apparatus of claim 1, wherein said member includes a portion
which is adjacent said antifriction bearing means and is disposed
at a first radial distance from the axes of said flywheels, said
friction generating device being disposed at a second radial
distance from said axes and said second distance at least
approximating said first distance, said friction generating device
engaging said portion of said member..]..[.
8. The apparatus of claim 1, wherein said one flywheel comprises an
axial protuberance having an external shoulder and an end face, and
further comprising a disc at said end face, said antifriction
bearing means including a race disposed between said shoulder and
said disc..]..Iadd.
9. Apparatus for compensating for variations of torque, especially
for fluctuations of torque which is transmitted between a
combustion engine and an input means of a transmission,
comprising:
at least two flywheels which are rotatable relative to each other
about a predetermined axis, one of which is connectable with the
engine and the other of which is connectable with the input means
of the transmission by way of an engageable and disengageable
friction clutch mounted on said other flywheel, said other flywheel
having a shoulder;
damper means arranged to oppose rotation of said flywheels relative
to each other, said damper means at least comprising energy storing
means acting in a circumferential direction of said flywheels and
being located at a first radial distance from said axis;
roller bearing means interposed between said flywheels;
a substantially disc-shaped member; and
means for preventing rotation of said member relative to said other
flywheel, including a form-locking connection provided between said
member and said other flywheel at a second radial distance from
said axis less than said first radial distance, said bearing means
being located between said shoulder and said member in a
predetermined axial position relative to said other flywheel and
said member having means for stressing said energy storing means in
said circumferential direction in response to rotation of said
flywheels relative to each other. .Iaddend..Iadd.
10. The apparatus of claim 9, wherein said friction clutch is
arranged to generate heat, and further comprising thermal insulator
means between said other flywheel and said bearing means to oppose
the transfer of heat from said friction clutch on said other
flywheel to said bearing means. .Iaddend..Iadd.
11. The apparatus of claim 9, further comprising a friction
generating device disposed between said flywheels, operating with
friction axially of said flywheels between said disc-shaped member
and said one flywheel, and comprising a friction ring and a
stressed energy storing element acting in the axial direction of
said flywheels. .Iaddend..Iadd.
12. The apparatus of claim 11, wherein the stressing of said energy
storing element of said friction generating device is such that
said energy storing element exerts a force having a component
acting against said other flywheel in a direction at least
substantially counter to the direction of action of force which is
to be applied to disengage the friction clutch. .Iaddend..Iadd.
13. The apparatus of claim 11, wherein said energy storing element
of said friction generating device reacts against said bearing
means. .Iaddend..Iadd.
14. The apparatus of claim 9, wherein said bearing means comprises
an inner race and an outer face surrounding said inner race, and
further comprising a thermal barrier between said bearing means and
said other flywheel, said thermal barrier comprising
heat-insulating rings each having a substantially L-shaped
cross-sectional outline and each including an annular portion
surrounding said outer race and a second portion extending radially
of said axis and sealingly engaging said inner race.
.Iaddend..Iadd.
15. The apparatus of claim 14, wherein one of said heat-insulating
rings is adjacent said disc-shaped member and another of said
heat-insulating rings is adjacent said shoulder of said other
flywheel. .Iaddend..Iadd.
16. The apparatus of claim 9, wherein said disc-shaped member
includes a portion which is adjacent said bearing means and is
disposed at a third radial distance from said axis, and further
comprising a friction generating device disposed between said
flywheels said flywheels at a fourth radial distance from said
axis, said fourth distance at least approximating said third
distance and said friction generating device engaging said portion
of said member. .Iaddend..Iadd.
17. The apparatus of claim 9, wherein said one flywheel comprises
an axial protuberance having an external shoulder and an end face,
and further comprising a disc at said end face, said bearing means
including a race disposed between said external shoulder of said
axial protuberance and said disc. .Iaddend..Iadd.
18. The apparatus of claim 9, wherein said damper means comprises
series-connected first and second dampers, said energy storing
means forming part of at least one of said first and second
dampers. .Iaddend..Iadd.
19. The apparatus of claim 9, wherein said bearing means has an
inner race and an outer race, said outer race being confined
between said shoulder of said other flywheel and said disc-shaped
member and said one flywheel having a second shoulder engaged by
said inner race and provided on a protuberance of said one
flywheel, said protuberance extending from an output element of the
engine and further comprising a sheet metal member and fastener
means securing said sheet metal member to said one flywheel, said
sheet metal member including a radially outer portion and said
inner race being secured between said radially outer portion of
said sheet metal member and said second shoulder.
.Iaddend..Iadd.
20. The apparatus of claim 9, further comprising a thermal
insulator having means for at least reducing the transfer of heat
between said other flywheel and said bearing means, said means for
at least reducing the transfer of heat comprising at least one
insulating ring which is disposed between said substantially
disc-shaped member and said shoulder of said other flywheel, said
at least one insulating ring having a first section surrounding an
outer race of said bearing means and at least one second section
extending substantially radially inwardly of said first section
toward an inner race of said bearing means. .Iaddend..Iadd.
21. The apparatus of claim 20, wherein said at least one second
section of said insulating ring includes a portion in sealing
engagement with said inner race. .Iaddend..Iadd.
22. The apparatus of claim 20, wherein said at least one second
section of said insulating ring is resilient and bears against said
inner race of said bearing means. .Iaddend..Iadd.
23. The apparatus of claim 20, further comprising means for biasing
said at least one second section of said insulating ring against
said inner face of said bearing means, said biasing means
comprising a diaphragm spring. .Iaddend..Iadd.
24. The apparatus of claim 20, further comprising a seal between
said thermal insulator and said outer race of said bearing means.
.Iaddend..Iadd.
25. The apparatus of claim 9, wherein said other flywheel has a
friction surface cooperating with a clutch plate of said friction
clutch, said other flywheel further having a side facing the engine
and axially extending passages disposed radially intermediate said
friction surface and said bearing means for streams of cooling air
flowing from the clutch through said passages toward said side of
said other flywheel and substantially radially outwardly through a
space between said flywheels, and further comprising an insulator
between said bearing means and said other flywheel.
.Iaddend..Iadd.
26. The apparatus of claim 25, wherein said damper means has at
least one wall positioned to be contacted by cooling air.
.Iaddend..Iadd.
27. The apparatus of claim 25, wherein said passages are elongated
in the circumferential direction of said other flywheel.
.Iaddend..Iadd.
28. The apparatus of claim 25, wherein said passages have
slot-shaped portions at said friction surface and their
cross-sectional areas increase toward said side of said other
flywheel. .Iaddend..Iadd.
29. The apparatus of claim 25, wherein said passages resemble
passages of air circulating vanes. .Iaddend..Iadd.
30. The apparatus of claim 25, wherein said passages are adjacent
said bearing means. .Iaddend..Iadd.
31. The apparatus of claim 25, wherein said passages include
substantially radially outwardly extending recesses in said side of
said other flywheel and extend along at least a portion of the
width of said friction surface in the radial direction of said
other flywheel. .Iaddend..Iadd.
32. The apparatus of claim 25, wherein said other flywheel has
internal surfaces surrounding said passages and at least one of
said passages includes an inner portion nearer to said axis and an
outer portion more distant from said axis, said inner portion
extending from said friction surface in at least substantial
parallelism with said axis and said outer portion diverging
radially outwardly from said axis toward said side of said other
flywheel. .Iaddend..Iadd.
33. The apparatus of claim 25, wherein said passages are uniformly
distributed about said axis. .Iaddend..Iadd.
34. The apparatus of claim 25, wherein said passages from a circle
around said axis and said circle has a center located at least
close to said axis. .Iaddend..Iadd.
35. The apparatus of claim 25, wherein said passages have a
combined length, as seen in the circumferential direction of said
other flywheel, which is between 20 and 70 percent of the total
length of the corresponding portion of said other flywheel.
.Iaddend..Iadd.
36. The apparatus of claim 25, wherein said other flywheel has webs
which alternate with said passages in the circumferential direction
of said other flywheel, said passages having a first width in said
circumferential direction and said webs having a second width
between 0.5 and 2.5 times said first width. .Iaddend..Iadd.
37. The apparatus of claim 25, wherein said damper means further
comprises an output member including said disc-shaped member, and
said form-locking connection includes fasteners alternating with
said passages in the circumferential direction of said other
flywheel. .Iaddend..Iadd.
38. The apparatus of claim 37, wherein said damper means further
comprises friction generating means. .Iaddend..Iadd.
39. The apparatus of claim 37, wherein said fasteners alternate
with pluralities of passages in the circumferential direction of
said other flywheel. .Iaddend..Iadd.
40. The apparatus of claim 39, wherein said other flywheel further
comprises narrower first webs between the passages of said
pluralities of passages and wider second webs connected to said
fasteners. .Iaddend..Iadd.
41. The apparatus of claim 40, wherein the width of each second web
equals or approximates the combined width of two first webs.
.Iaddend..Iadd.
42. The apparatus of claim 25, wherein said insulator comprises
means for at least impeding the transmission of heat from said
friction surface to said bearing means, including at least one ring
having a substantially L-shaped cross-sectional outline.
.Iaddend..Iadd.
43. The apparatus of claim 42, wherein said means comprises a first
race and a second race, said at least one ring including a first
portion extending along one of said races in the direction of said
axis and a second portion extending along the other of said races
substantially radially of said axis. .Iaddend..Iadd.
44. The apparatus of claim 43, wherein at least one of said
portions of said at least one ring sealingly engages the respective
race. .Iaddend..Iadd.
45. The apparatus of claim 42, wherein said insulator further
comprises a diaphragm spring reacting against said other flywheel
and bearing against said at least one ring to bias one of said
portions of said at least one ring against the respective race.
.Iaddend..Iadd.
46. The apparatus of claim 45, wherein said diaphragm spring reacts
against a radially outer portion of said other flywheel and bears
axially against the second portion of said at least one ring.
.Iaddend..Iadd.
47. The apparatus of claim 25, wherein said flywheels include a
first flywheel having an axial protuberance and a second flywheel
having a centrally located recess for said protuberance, said
bearing means surrounding said protuberance in said recess and said
insulator being disposed in said recess between said bearing means
and said second flywheel. .Iaddend..Iadd.
48. The apparatus of claim 25, wherein said insulator constitutes
the only means for sealing said bearing means. .Iaddend..Iadd.
49. The apparatus of claim 9, wherein said friction clutch has a
clutch plate engageable by a friction surface of said other
flywheel, said bearing means including a first race and a second
race and said other flywheel further having substantially axially
extending air conveying passages disposed radially between said
bearing means and said friction surface, and further comprising an
insulator having means for at least impeding the transmission of
heat including at least one ring having a substantially L-shaped
cross-sectional outline and including a first portion extending
along one of said races in the direction of said axis and a second
portion extending along the other of said races substantially
radially of said axis, said insulator further having a diaphragm
spring reacting against a radially outer portion of said other
flywheel and bearing against a radially inner portion of said
second portion of said at least one ring in the direction of said
axis to maintain said second portion of said at least one ring in
sealing engagement with said other race. .Iaddend..Iadd.
50. The apparatus of claim 49, wherein said other flywheel has a
side confronting the engine and adjacent a wall of said damper
means, said passages being elongated in the circumferential
direction of said other flywheel and being configured to convey
streams of cooling air from said friction clutch to said side of
said other flywheel against said wall of said damper means and
substantially radially outwardly through a space between said
flywheels. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to torque transmitting and torsion
damping apparatus, especially to improvements in torque
transmitting and torsion damping apparatus which can be utilized in
motor vehicles to compensate for fluctuations of torque which is
transmitted between driving and driven components, particularly
between the crankshaft of the internal combustion engine and the
input shaft of the change-speed transmission in a passenger car or
another motor vehicle.
It is already known to provide a torsion damping apparatus, which
is installed in a motor vehicle between the crankshaft of the
internal combustion engine and the input shaft of the change-speed
transmission, with several flywheels which are rotatable relative
to each other within certain limits and against the opposition of
one or more dampers. Such apparatus are disclosed, for example, in
commonly owned copending patent application Ser. No. 669,657 of
Oswald Friedmann as well as in several other pending applications
of the assignee. The flywheels can rotate relative to each other
about the axis or axes of one or more bearings. A friction clutch
is interposed between the last flywheel and the input shaft of the
transmission, and such friction clutch includes a disc which is
movable into and out of friction- and heat-generating engagement
with the adjacent flywheel. This can adversely influence the
operation and useful life of the bearing, especially if the races
of the bearing are directly connected to or in direct contact with
the adjacent flywheels. Thus, one race of an antifriction ball
bearing between two coaxial flywheels which can move angularly
relative to each other against the opposition of one or more
dampers can be non-rotatably secured to one of the flywheels, and
the other race of the bearing can be non-rotatably secured to the
other flywheel. It has been found that the just described mounting
of the flywheels on an antifriction bearing enables the damper or
dampers to produce a highly satisfactory damping action.
Nevertheless, such torsion damping apparatus failed to gain
popularity in the automotive and other industries, primarily
because the useful life of the bearing or bearings between the
flywheels is relatively short. The bearing or bearings are one of
the critical elements in these torsion damping apparatus so that
their failure after a relatively short interval of use deters the
manufacturers of motor vehicles from employing such torsion damping
apparatus between the engine and the change-speed transmission.
A torque transmitting and torsion damping apparatus between the
input shaft of a change-speed transmission and the output shaft of
an engine must be capable of taking up stresses, such as those
attributable to fluctuations of transmitted torque, which develop
while a rotary driving element transmits torque to a rotary driven
element. As a rule, or in many instances, the crankshaft of the
engine is attached directly to a first flywheel, the input shaft of
the transmission can receive torque from a second flywheel by way
of a friction clutch, and the means for transmitting torque between
the flywheels comprises one or more dampers which oppose angular
movements of the flywheels relative to each other. The second
flywheel has a friction surface which is engaged by a lining of the
clutch disc of the friction clutch when the latter is engaged to
transmit torque from the second flywheel to the transmission. The
bearing or bearings between the flywheels have pairs of races
confining single or multiple rows of antifriction rolling elements
in the form of needles, balls, rollers or the like. The bearing or
bearings enable the torque transmitting and torsion damping
apparatus to perform a highly satisfactory damping of oscillations
which develop in the power train between the engine and the
transmission. Nevertheless, and as already stated above, such
apparatus failed to gain widespread acceptance due to the short
useful life of the bearing or bearings. As a rule, the bearing or
bearings constitute the first part or parts which require
replacement, and such replacement must take place after a
relatively short period of use.
One of the main reasons that the useful life of the antifriction
bearing or bearings between the flywheels of the above outlined
torque transmitting apparatus is relatively short is that the
bearings are subjected to pronounced thermal stresses, primarily
because the friction clutch between the input element of the
change-speed transmission and the respective flywheel invariably
generates heat when it is called upon to transmit torque to the
transmission.
The damper or dampers which are provided between the relatively
movable flywheels of the just outlined torque transmitting
apparatus normally comprise at least one set of coil springs or
analogous energy storing elements which yieldably oppose angular
movements of the flywheels relative to each other, as well as one
or more friction generating devices each of which can oppose some
or all angular movements of the flywheels relative to one another.
The damper or dampers contribute significantly to the initial and
maintenance cost of the torque transmitting apparatus.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the invention is to provide a torsion damping
apparatus which can be used in motor vehicles as a superior
substitute for heretofore known torsion damping apparatus and is
constructed, dimensioned and assembled in such a way that it and
its bearing or bearings can stand long periods of use.
Another object of the invention is to provide a torsion damping
apparatus wherein the bearing or bearings between the flywheels can
be shielded from undesirable influences of the adjacent parts of
the apparatus in a simple and inexpensive but efficient way.
A further object of the invention is to provide a torsion damping
apparatus wherein the damper or dampers can perform their functions
more efficiently than in heretofore known apparatus, even though
their construction need not depart, or need not appreciably depart,
from the construction of dampers in conventional torsion damping
apparatus.
An additional object of the invention is to provide a novel and
improved method of shielding the bearing or bearings and/or the
damper or dampers of a torsion damping assembly from undesirable
influences of other component parts of the apparatus, especially of
the friction clutch between one of the flywheels and the input
element of the change-speed transmission in a motor vehicle.
Still another object of the invention is to provide a torsion
damping apparatus which exhibits the above outlined features but
need not be bulkier, more complex and/or more expensive than
heretofore known apparatus.
A further object of the invention is to provide an apparatus which
is designed for controlled transmission of torque between the
crankshaft of the internal combustion engine and the input shaft of
the change-speed transmission in a motor vehicle and is capable of
effectively opposing and damping undesirable fluctuations of torque
in the power train between the engine and the wheels of the
vehicle.
Another object of the invention is to provide a novel and improved
method of combining the bearing or bearings with other parts of the
above outlined torsion damping apparatus.
Another object of the invention is to provide novel and improved
bearings for use in the above outlined torsion damping
apparatus.
An additional object of the invention is to provide novel and
improved flywheels for use in the above outlined torsion damping
apparatus.
A further object of the invention is to provide a novel and
improved method of preventing heat from adversely influencing the
bearing or bearings and/or other sensitive parts of a torsion
damping apparatus of the type wherein a flywheel can transmit
torque to a rotary element by way of a friction clutch.
An additional object of the invention is to provide a novel and
improved device for preventing heat which is generated during
actual use of the torsion damping apparatus from affecting the
useful life of certain sensitive parts including the bearing or
bearings and one or more dampers.
Another object of the invention is to provide novel and improved
means for preventing escape of lubricant from the bearing or
bearings in a torsion damping apparatus of the above outlined
character.
A further object of the invention is to provide a torsion damping
apparatus wherein the useful life of the bearing or bearings can
match the useful life of other constituents.
Another object of the invention is to provide the above outlined
apparatus with novel and improved means for preventing the heat
which is generated by the friction clutch from adversely
influencing the bearing or bearings between the flywheels.
A further object of the invention is to provide a relatively
simple, compact and inexpensive torque transmitting apparatus which
can be used with particular advantage between the crankshaft of the
internal combustion engine and the input element of the
change-speed transmission in a motor vehicle.
An additional object of the invention is to provide a novel and
improved method of shielding the bearing or bearings between the
flywheels from excessive thermally induced stresses.
Still another object of the invention is to provide an apparatus of
the above outlined character whose components can be assembled or
taken apart in a simple and time-saving manner and which can
automatically ensure uniform wear upon the component parts of the
bearing or bearings between the flywheels.
A further object of the invention is to provide the apparatus with
novel and improved means for damping and opposing the movements of
flywheels relative to each other.
A further object of the invention is to provide a novel and
improved mounting for the bearing or bearings between the flywheels
as well as to provide novel and improved damper means between such
flywheels.
Another object of the invention is to achieve the above-enumerated
objects in a simple and inexpensive way.
Another object of the invention is to provide the apparatus with
novel and improved means for prolonging the useful life of the
antifriction bearing or bearings between the components of its
flywheel.
A further object of the invention is to provide novel and improved
means for withdrawing heat and for keeping heat away from the
bearing or bearings of the above outlined apparatus.
Still another object of the invention is to provide the torque
transmitting apparatus with a simple and inexpensive flywheel and
with novel and improved means for cooling one or more parts of the
friction clutch between the flywheel and the input shaft of the
change-speed transmission.
An additional object of the invention is to provide an apparatus
wherein heat is withdrawn from the friction clutch in a direction
to avoid the transfer of such heat to sensitive parts of the
apparatus.
A further object of the invention is to provide a power train which
embodies the above outlined apparatus and to provide a motor
vehicle which embodies the power train and the apparatus.
An additional object of the invention is to provide a novel and
improved method of cooling the flywheel, the antifriction bearing
means and/or the clutch in the above outlined apparatus.
Another object of the invention is to provide a novel distribution
of heat barriers in the flywheel or flywheels of the above outlined
apparatus.
An additional object of the invention is to provide a torque
transmitting apparatus which is constructed and assembled in the
above-outlined manner and can be installed in the power trains of
existing motor vehicles.
The invention is embodied in a torsion damping apparatus which is
especially suited to take up and to compensate for fluctuations of
torque which is transmitted from the crankshaft of the internal
combustion engine to the rotary input element of the change-speed
transmission in a motor vehicle.
One embodiment of the improved torsion damping apparatus comprises
a plurality of flywheels including preferably but not necessarily
coaxial first and second flywheels which are movable angularly
relative to each other, single or plural damper means operating
between the first and second flywheels to yieldably oppose angular
movements of such flywheels relative to each other, bearing means
(e.g., one or more antifriction needle, ball or roller bearings
with coaxial inner and outer races) which is interposed between the
first and second flywheels and has at least one row of antifriction
rolling elements, and a friction clutch which is operable to
receive torque from one of the first and second flywheels with
attendant generation of heat. The one flywheel and the friction
clutch have cooperating first and second friction- and
heat-generating surfaces (the first friction generating surface can
constitute one side face or end face of the one flywheel, and the
second surface can constitute the exposed surface of one friction
lining on a clutch disc forming part of the friction clutch and
serving to transmit torque to the input element of the change-speed
transmission), and the improved torsion damping apparatus further
comprises one or more thermal barriers and/or other suitable means
for impeding (preferably blocking) the transfer of heat from the
first surface to the bearing means.
The impeding means can be installed between the bearing means and
the one flywheel. One race of the bearing means can be
non-rotatably installed in the one flywheel, and the impeding means
(e.g., a thermal barrier) can be mounted between such one race and
the one flywheel.
The impeding means can contain or can consist of a synthetic
plastic material, a metallic material or a ceramic material. For
example, the impeding means can contain a duroplast i.e., a
thermosetting resin (e.g., a phenoplast in the form of hard paper).
If the impeding means is made of or contains a thermoplastic
material, such material can be selected from the group consisting
of polytetrafluoroethylene, polyimide and polyamidimide. It is
further possible to make the thermal barrier of a material which
contains a polycarbonate, especially a fiber-reinforced
polycarbonate.
The first flywheel can be formed with a central protuberance and
the second flywheel is then provided with a centrally located
recess which receives at least a portion of the protuberance as
well as a portion of or the entire bearing means which then
surrounds a portion of or the entire protuberance. The impeding
means is or can be mounted in the recess and at least partially
surrounds or is surrounded by the bearing means, depending upon
whether the recess is provided in the one flywheel or in the other
of the first and second flywheels. For example, one race of the
bearing means can be arranged to rotate with the one flywheel, and
the impeding means can be interposed between such race and the one
flywheel so that it rotates with the one flywheel. The other race
of the bearing means then surrounds the protuberance of the other
of the first and second flywheels. The impeding means can be
integral with the bearing means; for example, such impeding means
can comprise a thermal barrier which is bonded to the bearing means
in an extruding or injecting molding machine. Also, if the thermal
barrier contains sintered material, such material can be integral
with the bearing means. Alternatively, the thermal barrier can be a
press fit on or in the bearing means, it is also possible to
assemble the bearing means and the first flywheel into a
prefabricated unit which fits, with a certain annular clearance,
into a centrally located recess of the second flywheel and such
clearance is filled with a mass of plastic material which is
allowed to set and can constitute or form part of the impeding
means. The hardened plastic material then surrounds the outer race
of the bearing means and can be inserted into the centrally located
recess of the one flywheel, i.e., of that flywheel which can
transmit torque to the input element of the change-speed
transmission in response to engagement of the friction clutch.
The impeding means can include or constitute a means for sealingly
engaging (e.g., surrounding) at least a portion of the bearing
means.
The impeding means can comprise a ring-shaped thermal barrier
including a substantially cylindrical section which overlaps the
first race of the bearing means, and at least one radially disposed
section which extends from the cylindrical section toward the other
race of the bearing means. One of the races surrounds the other
race, and the cylindrical section can surround the outer of the two
races. The ring-shaped thermal barrier can have a substantially
L-shaped cross-sectional outline, and the radially extending
section of such thermal barrier can include an annular portion
(e.g., an annular marginal portion) which bears against the other
race of the bearing means, as considered in the axial direction of
the flywheels. The impeding means can comprise two mirror
symmetrical rings each of which has an L-shaped cross-sectional
outline and whose cylindrical sections surround the outer race of
the bearing means. The radial sections of such rings extend from
the respective cylindrical sections along the corresponding end
faces of the two races, and each radial section thereof can extend
across the corresponding end of the annular clearance between the
inner and outer races of the bearing means. Thus, the outer race of
the bearing means is then disposed between the radial sections of
the two rings which constitute or form part of the impeding means.
The two rings are mirror symmetrical to each other with reference
to a plane which is disposed between them and is normal to the
common axis of the flywheels.
Each radial section can be biased axially of the flywheels and
against the respective end face of the inner race by a diaphragm
spring or by other suitable biasing means. The outer marginal
portion of each diaphragm spring can react against the one
flywheel, and the inner marginal portion of each diaphragm spring
then bears against the radial section of the respective ring. Such
inner marginal portions can cause the aforediscussed annular lips
(if any) of the radial sections to bear against the respective end
faces of the inner race.
A sleeve-like section of a thermal barrier which constitutes or
forms part of the impeding means can be a press fit in the
centrally located recess of the first or second flywheel. The
sleeve-like section and the bearing means can constitute a
prefabricated unit which is received in the recess. The sleeve-like
section of the thermal barrier can surround the outer race of the
bearing means and its thickness, as considered radially of the
flywheels, can vary in the axial direction of the bearing means. At
least the thicker portion of the sleeve-like section can be a press
fit in the recess of the first or second flywheel.
The ring or rings of the thermal barrier can define with one of the
races one or more annular chambers for suitable sealing means, such
as one or more O-rings. For example, if the thermal barrier
comprises a single ring having a substantially L-shaped
cross-sectional outline, the cylindrical section of the ring can
surround the external surface of the outer race of the bearing
means, the radial section of the ring can extend from the
cylindrical section inwardly along one end face of the outer race
and along the corresponding end face of the inner race, and the
annular chamber can be provided at the junction of the two
sections, i.e., in the region where the one end face of the outer
race meets the peripheral surface of the outer race. The chamber
can be formed by providing the outer race of the bearing means with
an annular groove. The sealing means (such as the aforementioned
O-ring) can be received in the chamber and can be compressed
therein by a shoulder of the outer race of the bearing means.
The thermal barrier can comprise a ring-shaped section having a
frustoconical external and/or internal surface in contact with a
complementary surface of the one flywheel and/or the outer race of
the bearing means. Means (such as the aforementioned diaphragm
spring) can be provided to bias the ring-shaped section of the
thermal barrier axially in the direction of the taper of the
ring-shaped section, i.e., so that the larger-diameter end of the
frustoconical internal surface or the smaller-diameter end of the
frustoconical external surface is the leading end of the
ring-shaped section. Such section can constitute a split ring, or
it can be assembled of two or more discrete arcuate sections. If
the thermal barrier further comprises at least one sealing element,
the latter extends radially of the ring-shaped section and toward
that race of the bearing means which is not in contact with the
cylindrical part of the ring. A diaphragm spring or other means can
be provided to bias the sealing element axially against that race
which is not engaged by the cylindrical part of the ring, for
example, to bias an annular lip of the sealing element against the
adjacent race of the bearing means. The ring can include a radial
section which is disposed opposite the sealing element and can
constitute an integral part of the cylindrical section. The radial
section and the sealing element then flank the two races of the
bearing means.
The means for impeding the transfer of heat to the bearing means
can perform the function or cooperates with the aforementioned
damper means which yieldably opposes angular movements of the
flywheels relative to each other. The clutch preferably comprises a
clutch disc, and the first surface of the one flywheel is adjacent
the clutch disc. The clutch also comprises means (e.g., a diaphragm
spring) for biasing the first surface of the one flywheel and the
clutch disc into frictional engagement with each other when the
clutch is engaged whereby the clutch causes the generation of heat
which is transmitted to the one flywheel. The opposing means may
but need not constitute the only means which tends to resist
angular movements of the flywheels relative to each other.
The bearing means can comprise an antifriction needle, ball or
roller bearing having a race for the rolling elements. The race is
adjacent and preferably rotates with the one flywheel, and the
opposing means preferably includes a first portion (e.g., the
annular portions of two mirror symmetrical rings each of which has
a substantially, L-shaped cross-sectional outline) which is
interposed between the race and the one flywheel, and a second
portion (e.g., the radially extending portions of the
aforementioned rings) which is in direct or indirect frictional
engagement with the other flywheel. The antifriction bearing
preferably further comprises a second race which is connected to
and shares the angular movements of the other flywheel. The second
portion of the opposing means is or can be in direct frictional
engagement with the second race. As mentioned above, the second
portion of the opposing means can extend substantially radially of
the flywheels and of the antifriction bearing, and the first
portion of such opposing means preferably extends circumferentially
of the race which rotates with the one flywheel. The radially
extending portions of the rings preferably abut, or are at least
adjacent, the end faces of the second race, i.e., of that race
which shares the angular movements of the other flywheel.
The opposing means can further comprise one or more dished springs
or analogous energy storing means for at least indirectly biasing
the second portions of the rings against the other flywheel, e.g.,
by biasing such second portions axially of the flywheels against
the end faces of the race which rotates with the other flywheel. A
first portion of each dished spring can react against the one
flywheel, and a second portion of each dished spring (such second
portions are preferably disposed radially inwardly of the
respective first portions) bears against the second portion of the
corresponding ring. The distance between the second portions of the
dished springs and the axes (e.g., the common axis) of the
flywheels preferably equals or approximates the distance between
such axes and those parts of the second portions of the rings which
bear against the end faces of the second race and/or directly
against the other flywheel.
The bias of one of the dished springs can exceed the bias of the
other dished spring so that the rolling elements of the bearing
means are clamped between the two races when the clutch is
disengaged in that the second race tends to move axially with
reference to the race which rotates with the one flywheel. The
force which is required to disengage the clutch and acts axially of
the flywheels is opposed by the one dished spring i.e., the force
of the one dished spring must be overcome in order to disengage the
clutch. The second portions of the rings can further serve as a
means for at least substantially sealing the axial ends of the
annular space which is defined by the two races of the bearing
means and receives the rolling elements.
A further feature of the invention resides in the provision of an
apparatus wherein the friction clutch has a clutch plate having the
aforementioned second surface which is engageable with the (first)
surface of the one flywheel. The damping means of such apparatus
can comprise two series-connected damping units and one or more
friction generating units which are interposed between the
flywheels to yieldably oppose rotation of the flywheels relative to
each other. The first surface and the bearing means are preferably
spaced apart from each other in the radial direction of the
flywheels, and the impeding means of such apparatus includes a
portion of the one flywheel; to this end, the one flywheel is
provided with substantially axially extending passages which are
disposed intermediate the bearing means and the first surface,
i.e., radially outwardly of the bearing means.
At least one passage is or can be elongated, e.g., at least one
passage can constitute a slot and the passages preferably form an
annulus which surrounds the bearing means.
In accordance with a presently preferred embodiment of this
apparatus, each passage has a slot-shaped end portion in the first
surface, and the cross-sectional area of at least one passage
increases in a direction away from the first surface (preferably
close to or all the way to an additional surface of the one
flywheel opposite the first surface). The arrangement may be such
that the internal surfaces which bound some or all of the passages
resemble the surfaces surrounding fluid-circulating vanes or
blades.
The passages are or can be adjacent (particularly closely adjacent)
the bearing means (the latter can include one or more radial and/or
axial antifriction bearings with a pair of races and needle-,
roller- or ball-shaped rolling elements between the races).
Those end portions of the passages which are provided in the
additional surface of the one flywheel preferably extend
substantially radially outwardly away from the bearing means. The
just discussed end portions of the passages can extend at least
close to or all the way to and even beyond the radially outermost
portion of the first surface.
The internal surfaces which bound the passages can include inner
portions which are nearer to the axes of the flywheels and extend
in substantial parallelism with such axes all the way between the
first and additional surfaces of the one flywheel, and outer
portions which are more distant from the axes of the flywheels and
extend in a direction from the first surface and radially of and
away from the axes of the flywheels.
The passages are, or can be, equidistant from each other in the
circumferential direction of the one flywheel, and they preferably
form an annulus with its center on the axes of the flywheels. The
combined length of the passages (as measured in the circumferential
direction of the one flywheel) can be between 20 and 70 percent of
the corresponding portion of the one flywheel. The one flywheel
comprises webs which alternate with the passages of the
aforementioned annulus, and the width of each such web (measured in
the circumferential direction of the one flywheel) can be between
0.5 and 2.5 times the width of a passage. The webs can be said to
constitute, or they can be designed to constitute, heat barriers
between the passages. Such heat barriers are integral portions of
the one flywheel, and they cooperate with the streams of air
flowing through the passages when the one flywheel rotates to
prevent an overheating of the bearing means.
The damping means can comprise an annulus of rivets or analogous
fasteners which are fixed to the one flywheel and alternate with
the passages (as considered in the circumferential direction of the
one flywheel). The fasteners can be used to attach a disc- or
flange-like output member of the damping means to the one flywheel.
The diameter of the annulus which is formed by the passages can
closely approximate or equal the diameter of the annulus of
fasteners. Such fasteners extend through at least some of the
aforementioned web-like heat barriers of the one flywheel. The
fasteners can alternate with pairs of passages (as considered in
the circumferential direction of the one flywheel). The webs can
include wider webs and narrower webs, and the fasteners are
preferably secured to the wider webs. The width of each wider web
can equal or approximate the combined width of the two narrower
webs.
The novel features which are considered as characteristic of the
invention are set forth in particular in the appended claims. The
improved apparatus itself, however, both as to its construction and
its mode of operation, together with additional features and
advantages thereof, will be best understood upon perusal of the
following detailed description of certain specific embodiments with
reference to the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an axial sectional view of a torsion damping apparatus
which is installed in a motor vehicle and wherein the means for
impeding the transfer of heat from the friction clutch to one of
the flywheels is constructed, assembled and mounted in accordance
with a first embodiment of the invention;
FIG. 2 is a fragmentary axial sectional view of a second torsion
damping apparatus wherein the means for impeding the transfer of
heat to the bearing means and one race of the bearing means define
two chambers for sealing rings;
FIG. 3 is a similar fragmentary axial sectional view of a third
torsion damping apparatus wherein the means for impeding the
transfer of heat to the bearing means includes a single ring with a
substantially L-shaped cross-sectional outline and a substantially
washer-like sealing element;
FIG. 4 is a similar fragmentary axial sectional view of a further
torsion damping apparatus wherein the means for impeding the
transfer of heat to the bearing means is integral with one of the
flywheels and/or with the bearing;
FIG. 5 is a fragmentary axial sectional view of an additional
apparatus wherein a thermal barrier of the means for impeding the
transfer of heat is located radially inwardly of the inner race of
the antifriction bearing;
FIG. 6 is an axial sectional view of a further torque transmitting
apparatus which embodies the invention, the output element of an
integral combustion engine and the input element of a change-speed
transmission being indicated by phantom lines;
FIG. 7 is an enlarged view of a detail within the phantom-line
circle Z of FIG. 6;
FIG. 8 is a similar enlarged view of a detail in a modified torque
transmitting apparatus;
FIG. 9 is an axial sectional view of a further apparatus which
embodies the invention; and
FIG. 10 is a fragmentary transverse sectional view as seen in the
direction of arrows from the line X--X of FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The torsion damping apparatus 1 of FIG. 1 comprises a composite
flywheel 2 including a first flywheel 3 receiving torque from an
internal combustion engine 105 by way of a crankshaft 5 which is
secured thereto by an annulus of bolts 6 or analogous fasteners,
and a second flywheel 4 which transmits torque to the input element
10 of a change-speed transmission 110 in a motor vehicle by way of
a friction clutch 7. The friction clutch 7 comprises an axially
shiftable pressure plate 8, an axially fixed pressure plate which
constitutes the second flywheel 4, a clutch plate or disc 9 with
two friction linings 9a, a cover or housing 11 and a diaphragm
spring 12 which normally urges the pressure plate 8 against the
adjacent lining 9a so that the friction- and heat-generating
(second) surface 9b of the other lining 9a bears against the
adjacent friction- and heat-generating (first) surface 4a of the
flywheel 4. The diaphragm spring 12 is tiltably mounted between two
wire-like ring-shaped seats on the cover 11 by rivets 12a, and the
axially movable pressure plate 8 is non-rotatably affixed to the
flywheel 4 or to the cover 11 by leaf springs 8a. The cover 11
rotates with the flywheel 4 and with the pressure plate 8. The
central portion of the clutch disc 9 transmits torque to the input
element 10 of the transmission 110. The means for disengaging the
clutch 7 can comprise a bearing (not shown) which can act against
the radially inwardly extending prongs 12b of the diaphragm spring
12 in order to move the radially outermost portion of the diaphragm
spring axially in a direction away from the flywheel 4 so that the
leaf springs 8a can move the pressure plate 8 axially and away from
the flywheel 4 to thus terminate the torque-transmitting connection
between the flywheel 4 and the clutch disc 9, i.e., between the
crankshaft 5 and the input element 10.
The flywheels 3 and 4 are or can be coaxial and can perform limited
or unlimited angular movements relative to each other against the
opposition of a composite damper including a damper unit 13, a
friction generating unit 13a and a slip clutch 14 which is
connected in series with the damper unit 13.
The torsion damping apparatus 1 further comprises a bearing means
15 which is interposed between the flywheels 3 and 4 and, in the
embodiment of FIG. 1, comprises an antifriction ball bearing 16
with an inner race 19, an outer race 17 spacedly surrounding the
inner race 19 and a single row of spherical rolling elements 16a in
the bearing clearance between the two races. The outer race 17 is
installed in a centrally located recess or bore 18 of the flywheel
4, and the inner race 19 is mounted on a centrally located
cylindrical protuberance or hub 20 which is an integral part of the
flywheel 3, which extends axially in a direction away from the
crankshaft 5, and at least a portion of which is received in the
recess 18. The inner race 19 is a press fit on the protuberance 20
of the flywheel 3 and is held against any axial movement relative
to the protuberance 20 by a shoulder 21 of the flywheel 3 as well
as by an annular washer-like retaining element 22 which is affixed
to the protuberance 20 by screws 23 so that its left-hand end face
bears against the end face 20a of the protuberance 20.
The improved torsion damping apparatus 1 further comprises means
for impeding the transfer of heat from the friction- and
heat-generating surfaces 9b, 4a to the bearing means 15. In the
embodiment of FIG. 1, the heat transfer impeding means includes a
thermal insulator or barrier 24 which is installed between the
outer race 17 of the antifriction bearing 16 and the adjacent
portion of the flywheel 4, namely that portion of the flywheel 4
which directly surrounds the recess 18 therein. The construction,
composition and mounting of the thermal barrier 24 are such that it
at least strongly interferes with and appreciably reduces the
transfer of heat from the clutch disc 9 to the antifriction bearing
16. This reduces the likelihood of excessive thermal stressing of
the lubricant (e.g., grease) for the antifriction bearing 16 as
well as the likelihood of excessive thermally induced distortion
(expansion) of the antifriction bearing 16 which could result in
jamming of spherical rolling elements 16a between the races 17 and
19. The diameter of the recess 18 in the central portion of the
flywheel 4 is selected in such a way that the recess can receive
the outer race 17 of the antifriction bearing 16 as well as the
components of the thermal barrier 24. In other words, the diameter
of the recess 18 exceeds the outer diameter of the outer race
17.
The illustrated thermal barrier 24 comprises two rings 25, 26 which
are mirror symmetrical to each other with reference to a plane that
is disposed between them and is normal to the axes of the flywheels
3, 4 and antifriction bearing 16. Each of the rings 25, 26 has a
substantially L-shaped cross-sectional outline with a cylindrical
section 25a, 26a which surrounds the external surface of the outer
race 17 and a radially inwardly extending washer-like section 25b,
26b which extends along the respective end face of the outer race
17 and toward and along the respective end face of the inner race
19. The radially innermost annular portions or lips of the radial
sections 25b, 26b bear axially against the respective end faces of
the inner race 19. Thus, the sections 25b, 26b constitute sealing
elements which reduce the likelihood of penetration of foreign
matter into the annular bearing clearance between the races 17, 19
as well as the likelihood of escape of lubricant from such
clearance. The sealing action of radial sections 25b, 26b of the
rings 25, 26 is enhanced by discrete means for biasing the radially
innermost portions of such radial sections against the adjacent end
faces of the inner race 19. The biasing means comprises two
diaphragm springs 27, 28. The radially outermost portion of the
diaphragm spring 27 reacts against a shoulder provided therefor on
a disc 30 which is affixed to the flywheel 4 by rivet-shaped
distancing elements 29, and the radially innermost portion of the
diaphragm spring 27 bears against the radially innermost portion of
the radial section 25b of the ring 25. The radially outermost
portion of the diaphragm spring 28 reacts against a shoulder of the
flywheel 4, and its radially innermost portion bears against the
radially innermost portion of the radial section 26b of the ring
26.
In order to simplify and facilitate the assembly of the
antifriction bearing 16 with the flywheels 3 and 4, the cylindrical
sections 25a, 26a of the rings 25, 26 are forcibly fitted onto the
outer race 17 of the antifriction bearing 16 in a first step before
the bearing 16 and the rings 25, 26 thereon are forcibly inserted
into the recess 18 of the flywheel 4. The bearing 16 and the rings
25, 26 are thereupon additionally secured against axial movement
relative to the flywheel 4 in that the radial section 26b of the
ring 26 bears against an internal shoulder 31 of the flywheel 4 and
the radial section 25a of the ring 25 is caused to abut against the
disc 30 which, as mentioned above, is affixed to the flywheel 4 by
the distancing elements 29.
The damper unit 13 includes the disc 30 and a second disc 33 which
is held at a fixed distance from the disc 30 by the aforementioned
rivet-shaped distancing elements 29 which are anchored in the
flywheel 4. The shanks of such distancing elements extend through a
flange 32 which is disposed between the discs 30 and 33. The discs
30, 33 cannot rotate relative to each other and share all angular
movements of the flywheel 4. The flange 32 shares all angular
movements of the flywheel 3. The discs 30, 33 and the flange 32 are
provided with neighboring windows for energy storing devices in the
form of circumferentially acting coil springs 34 which oppose
angular movements of the flywheels 3 and 4 relative to each other,
i.e., such coil springs resist angular movements of the discs 30,
33 with reference to the flange 32 and vice versa.
The composite damper further includes the friction generating unit
13a which is active during each and every stage of angular movement
of the flywheel 3 relative to the flywheel 4 and/or vice versa. The
friction generating unit 13a acts axially between the disc 30 on
the flywheel 4 and the flywheel 3, and includes an energy storing
member in the form of a diaphragm spring 35 which is installed in
prestressed condition between the disc 30 and a pressure applying
washer 36. The diaphragm spring 35 can react against the flywheel 3
to bear against the washer 36 which, in turn, urges a friction ring
37 against the adjacent side of the disc 30 on the flywheel 4. The
axial stress which is applied by the diaphragm spring 35 is taken
up by the antifriction bearing 16.
The flange 32 constitutes the input element of the damper unit 13
as well as the output element of the slip clutch 14. The input
element of the slip clutch 14 is constituted by two discs 38, 39
which are maintained at a fixed axial distance from each other and
are non-rotatably secured to the flywheel 3. The means for
non-rotatably securing the disc 39 to the flywheel 3 comprises an
annulus of rivets 40. The disc 38 is provided with an annulus of
axially extending peripheral fingers or lugs 38a which extend into
adjacent peripheral notches 41 of the disc 39 so that the two discs
are held against angular movement relative to one another. The
flange 32 has radially outwardly extending arms 42 which are
clamped between the discs 38 and 39 by a diaphragm spring 43 which
urges the discs 38 and 39 toward each other. The diaphragm spring
43 reacts against the flywheel 3 and bears against the disc 38 in a
direction to urge the latter axially toward the disc 39. The arms
42 of the flange 32 alternate with windows which are provided in
the discs 38, 39 and receive energy storing devices in the form of
coil springs 44 which can be engaged by the respective arms 42 and
constitute stops that determine the extent of angular displacement
of the parts of the slip clutch 14 relative to each other.
It has been found that the thermal barrier 24 between the friction
clutch 7 and the bearing means 15 is capable of prolonging the
useful life of the bearing means as well as of ensuring more
satisfactory operation of the damper (13, 13a, 14) between the
flywheels 3 and 4. This is due to the fact that the thermal barrier
24 greatly reduces the transfer of heat to the bearing means 15
even though it takes up little room and is assembled of a small
number of simple, compact and inexpensive parts each of which can
be mass-produced in available machinery. Extensive experiments with
the improved torsion damping apparatus (wherein the bearing means
is installed directly between the two flywheels 3 and 4 and wherein
the angular movements of the flywheels relative to each other must
be damped by one or more discrete or interlinked dampers) indicate
that, in the absence of any preventive or precautionary measures,
heat energy which is released when the friction clutch 7 is engaged
subjects the bearing means between the flywheels to very pronounced
thermal stresses which entail unsatisfactory operation and
frequently rapid destruction of the bearing means as well as
unsatisfactory operation of the damper or dampers. The likelihood
of rapid destruction of the bearing means is especially pronounced
if the bearing clearance or tolerance between the inner and outer
races is small or very small. Repeated pronounced heating and
cooling of the parts of such bearing means entails substantial
thermally induced expansion and contraction whereby the rolling
elements between the two races are likely to seize in response to
expansion of the races which, in turn, entails rapid destruction of
the rolling elements and of the tracks which are machined into the
races. All this can be avoided by the advent of the present
invention, i.e., by the provision of a thermal barrier which at
least impedes the transfer of heat to the bearing means.
Another important advantage of the improved apparatus is that the
lubricant (such as oil or grease) in the bearing clearance between
the races of the bearing is much less likely to be overheated and
to escape from the bearing. This, too, contributes to longer useful
life of the bearing means and of the entire torsion damping
apparatus. Moreover, portions or sections of the rings 25, 26 which
constitute or form part of the improved thermal barrier 24 can
serve as an effective means for sealing the bearing clearance
between the races 17 and 19 to thereby even further reduce the
likelihood of escape of excessive quantities of lubricant from the
interior of the antifriction bearing 16. The aforediscussed
plastic, ceramic and/or metallic materials have been found to
constitute highly satisfactory thermal insulators which can protect
the antifriction bearing 16 and the units of the composite damper
for extended periods of time, even if the friction clutch 7 is
continuously engaged and/or is caused or permitted to slip (with
attendant pronounced generation of heat) at frequent and relatively
long intervals.
It was further ascertained that the placing of the thermal barrier
directly between the antifriction bearing 16 and the adjacent
portion of the flywheel 4 (i.e., of that flywheel which is directly
heated by the friction clutch 7) contributes significantly to
adequate shielding of the bearing means 15 from excessive heat
while, at the same time, allowing for relatively simple and
inexpensive installation of the thermal barrier in the torsion
damping apparatus. Of course, it is equally possible to employ two
or more thermal barriers or to provide one or more thermal barriers
in the body of the flywheels 4 and out of direct contact with the
antifriction bearing 16 but in the path of transfer of heat energy
from the friction generating surfaces 9b, 4a to the bearing 16.
The positions of the recess 18 and protuberance 20 can be reversed,
i.e., the protuberance can be provided on the central portion of
the flywheel 4 and the flywheel 3 is then formed with a recess
which receives at least a portion of the protuberance on the
flywheel 4, at least a portion of the bearing means on such
protuberance and at least a portion of the thermal barrier. The
thermal barrier is then preferably installed within the inner race
(which surrounds the protuberance of the flywheel 4) in order to
prevent overheating of the bearing means 15. This is shown in FIG.
5.
The thermal barrier 24 of FIG. 1 can be replaced with a thermal
barrier which comprises a single ring having a cylindrical section
which surrounds the major portion of or the entire outer race 17,
and a radial section which is adjacent one end face of the race 17
and extends radially inwardly toward and at least in part along one
end face of the inner race 19. The illustrated two-piece thermal
barrier 24 is preferred in many instances because the two radially
extending sections 25b, 26b constitute effective and relatively
simple as well as compact sealing elements which prevent the escape
of lubricant from the bearing clearance for the rolling elements
16a and also reduce the likelihood of overheating of the confined
lubricant and/or rolling elements. The provision of biasing means
(such as the aforementioned diaphragm springs 27 and 28) even
further reduces the likelihood of escape of excessive quantities of
lubricant and/or of overheating of the lubricant and/or rolling
elements in the bearing clearance between the races 17 and 19. The
diaphragm springs 27, 28 can be provided even if the sections 25b
and 26b are elastically deformable and the rings 25, 26 are
installed in such a way that the sections 25b, 26b are prestressed
and bear against the respective end faces of the inner race 19 even
if the diaphragm springs 27, 28 are omitted; however, these
diaphragm springs are then optional.
FIG. 2 shows a portion of a modified torsion damping apparatus with
coaxial flywheels 3, 4, a modified bearing means having an
antifriction ball bearing 116 between the two flywheels, and a
modified thermal barrier between the antifriction bearing 116 and
that portion of the flywheel 4 which is immediately adjacent the
outer race 117 of the bearing 116. Such portion of the flywheel 4
has a recess 118 which receives a portion of the outer race 117 as
well as portions of two mirror symmetrical insulating rings 125,
126 which constitute component parts of the thermal barrier. The
inner race 119 of the antifriction bearing 116 is a press fit on
the protuberance or hub 120 of the flywheel 3. The manner in which
the flywheel 4 cooperates with the friction clutch (not shown in
FIG. 2), and the manner in which the flywheel 3 receives torque
from the crankshaft of the engine is or can be the same as shown in
FIG. 1. The outer race 117 of the antifriction bearing 116 has
circumferentially extending annular chambers in the form of grooves
or recesses 117a, 117b which are overlapped in part by the
cylindrical sections 125a, 126a and in part by the inwardly
extending radial sections 125b, 126b of the respective rings 125,
126. Each of these rings has a substantially L-shaped
cross-sectional outline, the cylindrical sections 125a, 126a engage
with the peripheral surface of the outer race 117, and the radial
sections 125b, 126b extend radially inwardly along the respective
end faces of the races 117, 119 and have radially innermost annular
portions or lips 125c, 126c which are biased axially against the
adjacent end faces of the inner race 119 by two diaphragm springs
127, 128 which respectively react against the disc 130 and flywheel
4 and bear against the adjacent lips 125c, 126c. The disc 130 has a
shoulder for the radially outermost portion of the diaphragm spring
127, and the flywheel 4 has a shoulder for the radially outermost
portion of the diaphragm spring 128.
The chambers 117a, 117b respectively receive discrete sealing means
in the form of O-rings 145, 146 which cooperate with the lips 125c,
126c and diaphragm springs 127, 128, to prevent penetration of
foreign matter into the bearing clearance between the races 117,
119 as well as to prevent the escape of lubricant (e.g., grease)
from such clearance. The dimensions of the chambers 117a, 117b and
of the O-rings 145, 146 are selected in such a way that the O-rings
are at least slightly compressed so as to reliably prevent the
escape of lubricant from the clearance for the rolling elements of
the antifriction bearing 116.
FIG. 2 further shows that the thickness of the intermediate portion
of each of the radial sections 125b, 126b is less than the
thickness of the radially outermost or the radially innermost
(125c, 126c) portion of each such section. This enhances the
elasticity of the radial sections 125b, 126b and enables the
diaphragm springs 127, 128 to reliably hold the lips 125c, 126c in
sealing contact with the adjacent end faces of the inner race 119.
The cylindrical sections 125a, 126a can be a press fit in the
recess 118 of the flywheel 4, and they can be assembled with the
outer race 117 of the antifriction bearing 116 before the latter is
fitted onto the protuberance 120 and before the protuberance 120 is
introduced into the recess 118.
The diaphragm spring 127 and/or 128 can be omitted if the
corresponding radial section 125b and/or 126b is sufficiently
elastic to adequately bear against the respective end face of the
inner race 119 when the antifriction bearing 116 is properly
mounted on the protuberance 120 of the flywheel 3 and is adequately
received in the recess 118 of the flywheel 4. The same applies for
the radial sections 25b, 26b of the rings 25, 26 and for the
diaphragm springs 27, 28 of the apparatus 1 which is shown in FIG.
1. Thus, all that is necessary is to make the rings 25, 26 and/or
125, 126 of a suitable elastomeric material and to mount these
rings in such a way that their radial sections 25b, 26b and/or
125b, 126b are elastically deformed in fully assembled condition of
the respective apparatus to adequately bear against the inner race
19 or 119 and to thus prevent escape of lubricant from the
clearance between the races 17, 19 or 117, 119.
The O-rings 145 and 146 even further reduce the likelihood of
escape of lubricant from the bearing clearance between the races
117 and 119, even if the lubricant is subjected to the action of
very pronounced centrifugal forces.
Referring to FIG. 3, there is shown a portion of a further torsion
damping apparatus wherein the antifriction bearing 216 between the
coaxial flywheels 3 and 4 has an outer race 217 with a
frustoconical external or peripheral surface 217' abutting against
a complementary frustoconical internal surface 225a' of the tubular
section 225a of a split ring-shaped thermal barrier 225. The
section 225a has a frustoconical external surface 225a" whose taper
is counter to that of the internal surface 225a' and which is in
contact with a complementary frustoconical surface in the recess
218 of the flywheel 4. The illustrated section 225a can be replaced
with a section having a cylindrical internal surface and a
frustoconical external surface or vice versa. The external surface
of the outer race 217 or the surface in the recess 218 is then a
cylindrical surface.
The diaphragm spring 227 reacts against the disc 230 and biases the
ring-shaped thermal barrier 225 in the direction of taper of its
frustoconical surfaces 225a', 225a", i.e., in a direction to cause
the section 225a to penetrate deeper into the recess 218.
The thermal barrier of FIG. 3 further comprises a first sealing
element 226 which is a separately produced washer and extends
radially inwardly from the thinnest portion of the cylindrical
section 225a along the right-hand end faces of the races 217, 219
and carries at its radially innermost end an annular lip 226c which
is biased against the right-hand end face of the face 219 due to
innate elasticity of the sealing element 226 or due to the
provision of a suitable diaphragm spring (not specifically shown).
The radially inwardly extending section 225b of the ring-shaped
thermal barrier 225 constitutes a second washer-like sealing
element which is adjacent the left-hand end faces of the races 217,
219 and has a radially innermost portion in the form of an annular
lip bearing against the adjacent end face of the race 219 under the
action of the diaphragm spring 227, i.e., because the spring 227
urges the cylindrical section 225a deeper into the recess 218 of
the flywheel 4. The disc 230 is affixed to the flywheel 4, e.g., in
a manner as described for the disc 30 of FIG. 1. The sealing
elements 226 and 225b flank the antifriction bearing 216 and reduce
the likelihood of escape of lubricant from the annular clearance
for the rolling elements of the bearing 216. Portions of the
sealing elements 226, 225b have reduced thicknesses (see the
portion 226b) to enhance their elasticity and to further reduce the
likelihood of uncontrolled escape of lubricant from the clearance
for the rolling elements. In lieu of spheres, the antifriction
bearing 16, 116 or 216 can also employ barrel-shaped or needle-like
rolling elements without departing from the spirit of the
invention. Furthermore, the antifriction bearing can be provided
with two or more rows of antifriction rolling elements.
The material of the ring-shaped thermal barrier 225 and of the
sealing elements 226 is preferably a good insulator of heat.
The torsion damping apparatus which embodies the structure of FIG.
3 exhibits the advantage that the frustoconical parts 217 and 225
compensate for certain machining tolerances and ensure automatic
centering of the antifriction bearing 216 and thermal barrier when
the diaphragm spring 227 is caused to bear against the left-hand
side of the cylindrical section 225a and radial section or sealing
element 225b. Moreover, the structure which is shown in FIG. 3 can
automatically compensate for wear upon the parts of the
antifriction bearing 216, upon the ring-shaped part 225 of the
thermal barrier as well as upon the sealing element 226. The spring
227 ensures that the cylindrical section 225a is wedged in the
recess 218 of the flywheel 4, that the outer race 217 is wedged in
the cylindrical section 225a, and that the sealing element 226 is
adequately held between the outer race 218 and the adjacent
shoulder 231 of the flywheel 4 as well as that its lip 226c
sealingly engages the right-hand end face of the inner race 219.
The provision of a split ring 225 even further ensures adequate
wedging of the parts 225, 217 in the recess 218 of the flywheel
4.
It is further within the purview of the invention to provide the
improved torsion damping apparatus with a thermal barrier which
need not include any prefabricated parts in the form of rings
and/or washer-like sealing elements. For example, and as shown in
FIG. 4, the thermal barrier 324 can constitute a single piece of
thermoplastic or thermosetting material which is injected into the
recess 318 of the flywheel 4 around the outer race 317 of the
antifriction bearing 316. All that is necessary is to dimension the
outer race 317 and the recess 318 in such a way that the surfaces
bounding the recess and the surfaces bounding the outer race define
an annular space or compartment which can receive flowable plastic
material. When the plastic material sets, the resulting thermal
barrier 324 adequately fills the space between the race 317 and the
surfaces surrounding the recess 318 and impedes or totally prevents
the transfer of heat from the clutch disc (not shown) to the
antifriction bearing 316. The illustrated plastic thermal barrier
324 can be replaced with a barrier which consists of sintered
ceramic or metallic material. In each instance, the thermal barrier
is an integral part of the antifriction bearing 316 and/or of the
flywheel 4. It is also possible to apply an integral plastic,
ceramic or metallic thermal barrier to the inner race and/or outer
race of the antifriction bearing 316 before the latter is inserted
into the recess 318 or to apply the thermal barrier to the surfaces
bounding the recess 318 (so that the thermal barrier becomes an
integral part of the flywheel 4) before the antifriction bearing
316 is inserted into the thus obtained thermal barrier in the
recess 318.
The injection or another mode of introduction of a flowable
plastic, metallic or ceramic material into the space between the
surfaces bounding the recess 318 of the flywheel 4 and the exterior
of the antifriction bearing 316 is especially advantageous and
desirable if the bearing 316 is a commercially available
antifriction bearing which is already provided with sealing
elements 360 that prevent uncontrolled escape of lubricant from the
space between the two races. As mentioned above, all that is
necessary is to adequately select the dimensions of the surfaces
bounding the recess 318 so as to provide sufficient room for
introduction of a flowable material which is to form the thermal
barrier 324 and is to be integral with the outer race 317 and/or
with the flywheel 4.
The disc 330 is applied subsequent to introduction of the outer
race 317 into the recess 318, and the disc 320 is attached to the
flywheel 3 to hold the inner race 319 against axial movement.
Referring to FIGS. 6 and 7, there is shown an apparatus 401 which
transmits torque from a rotary output element 405 (such as the
crankshaft of an internal combustion engine in a motor vehicle) to
a rotary input element 410 (e.g., the input shaft of a change-speed
transmission in a motor vehicle). In order to render it possible to
absorb shocks which develop during transmission of torque, the
apparatus 401 comprises a composite flywheel 402 having two coaxial
flywheels 403 and 404 which have limited or full freedom of angular
movement relative to each other. The flywheel 403 is coaxially
secured to the output element 405 by a set of bolts 406 or by other
suitable fasteners. The flywheel 404 can transmit torque to the
input element 410 by way of a friction clutch 407 whose housing or
cover 411 is secured to the flywheel 404 by bolts, screws or like
fasteners, not shown. The clutch 407 further comprises a pressure
plate 408, a clutch disc 409 whose linings are disposed between a
radially extending surface 404a of the flywheel 404 and the
pressure plate 408 and whose hub is non-rotatably affixed to the
input element 410, and a diaphragm spring 412 which reacts against
the cover 411 and bears against the pressure plate 408 to bias the
latter against the respective friction lining whereby the other
friction lining bears against the surface 404a and the flywheel 404
rotates the input element 410 as long as the friction clutch 407
remains engaged. The diaphragm spring 412 is installed between two
ring-shaped seats in the form of wire rings which are supported by
the cover 411.
A damper 413 is installed between the flywheels 403 and 404 to
yieldably oppose the aforementioned angular movements of the
flywheels relative to each other. The apparatus 401 further
comprises antifriction bearing means 414 here shown as comprising a
ball bearing 415 with a single row of spherical rolling elements
415a between an outer race 416 and an inner race 418. The race 416
extends into an internal annular groove 417 of the flywheel 404,
and the race 418 surrounds a hub-shaped shaped central portion or
protuberance 419 of the flywheel 403. The protuberance 419 extends
axially of the flywheel 404 in a direction away from the output
element 405.
The inner race 418 is a press fit on the protuberance 419 and is
held against axial movement on such protuberance by a radially
outwardly extending shoulder 420 of the flywheel 403 in cooperation
with a washer-like retainer 421 which abuts the adjacent end face
422 of the protuberance 419 and is separably affixed to the latter
by screws 423 or by analogous fastener means.
In accordance with a feature of the embodiment of FIGS. 6 and 7,
the apparatus 401 further comprises a thermal barrier 424 which is
interposed between the race 416 of the ball bearing 415 and the
flywheel 404 so as to impede or fully prevent the transmission of
heat which is generated primarily as a result of frictional
engagement of the clutch plate 409 with the surface 404a of the
flywheel 404 when the friction clutch 407 is operative to transmit
torque from the flywheel 404 to the input element 410 of the
change-speed transmission. The purpose of the thermal barrier 424
is to prevent heat, which is generated in response to engagement of
the friction clutch 407, from adversely influencing (i.e., from
exerting excessive thermal stresses upon) the lubricant (grease)
which is used for the rolling elements 415a of the ball bearing
415. Furthermore, the barrier 424 prevents excessive thermally
induced deformation and radial expansion of the bearing 415 when
the left-hand lining of the clutch disc 409 is in frictional
engagement with the surface 404a of the flywheel 404. Excessive
radial expansion of the races 416 and 418 could entail a jamming of
the rolling elements 415a between the races. The diameter of the
surface in the deepmost portion of the recess 417 in the flywheel
404 is selected in such a way that certain parts of the thermal
barrier 424 can be installed in such recess and surround the outer
race 416 of the antifriction bearing 415.
As can be best seen in FIG. 7, the thermal barrier 424 comprises
two substantially or exactly mirror symmetrical rings 425, 426 each
of which has a substantially L-shaped cross-sectional outline. The
axially extending (annular) portions or legs 425a, 426a of the
rings 425, 426 are radially outwardly adjacent the outer race 416
of the ball bearing 415, and the radially inwardly extending
(washer-like) portions or legs 425b, 426b of these rings flank the
respective end faces of the race 416 and have radially innermost
parts or lips 434, 435 which abut the respective end faces 437, 438
of the inner race 418 to thereby oppose angular movements of the
race 418 and flywheel 403 relative to the race 416 and flywheel
404. Thus, the lips 434, 435 form part of the thermal barrier 424
as well as of the aforementioned damper 413 between the flywheels
403 and 404.
The radially extending legs 425b, 426b of the rings 425, 426
perform the additional function of confining the lubricant
(normally grease) for the rolling elements 415a in the space
between the races 416 and 418 of the ball bearing 415. The damping
and confining or sealing action of the legs 425b, 426b can be
enhanced and maintained at a selected optimum value or within a
predetermined optimum range by the provision of means for biasing
the lips 434, 435 against the respective end faces 437, 438 of the
inner race 418. Such biasing means comprises a first dished spring
427 whose radially outermost portion reacts against an internal
shoulder 430a of a disc 430 and whose radially innermost portion
bears against the lip 434 of the leg 425b, and a second dished
spring 428 whose radially outermost portion reacts against an
internal shoulder 431 of the flywheel 404 and whose radially
innermost portion bears against the lip 435 of the leg 426b. The
disc 430 is affixed to the flywheel 404 by a set of rivets 429.
FIG. 7 shows that the thickness of the median portions of the legs
425b, 426b is reduced so that such median portions constitute two
relatively thin and hence more readily flexible membranes 432, 433.
The lips 434, 435 are disposed radially inwardly of the respective
membranes 432 and 433 and bear against the respective end faces 437
and 438 of the inner race 418 with a force which is determined by
the bias of the respective dished springs 427 and 428. The initial
stressing of the dished springs 427 and 428 is selected in such a
way that the axially oriented force which is applied by the spring
428 exceeds the axially oriented force which is applied by the
spring 427. This ensures that the races 416 and 418 tend to move
axially and in opposite directions whenever the friction clutch 407
is idle whereby the rolling elements 415a are clamped between the
two races. The inner race 418 tends to move to the left, as viewed
in FIG. 7, because the bias of the dished spring 428 prevails over
that of the dished spring 427.
In order to simplify the assembly of the thermal barrier 424 with
the antifriction bearing 415, the annular portions 425a, 426a of
the rings 425, 426 are first force-fitted onto the peripheral
surface of the outer race 416 before the rings 425, 426 are
introduced into the recess 417 of the flywheel 404. The
antifriction bearing 415 is maintained in a predetermined axial
position with reference to the flywheel 4 because the outer side of
the properly installed radially extending leg 426b abuts an
internal shoulder 431a of the flywheel 404 and the radially
outermost portion of the outer side of the leg 425b abuts the
adjacent side of the aforementioned disc 430.
The damper 413 between the flywheels 403 and 404 further comprises
the aforementioned disc 430 as well as a second disc 440 whose
inner diameter is larger than that of the disc 430. The rivets 429
are configurated in such a way that they maintain the discs 430,
440 at a fixed axial distance from the surface 404a of the flywheel
404 as well as from each other. The discs 430, 440 flank (i.e.,
they are disposed at the opposite sides of) a flange 439 whose
radially outwardly extending prongs 439a are secured to the
flywheel 403 by rivets 442. The flange 439 and the discs 430, 440
have registering windows for energy storing elements in the form of
coil springs 441 whose function is to oppose angular movements of
the discs 430, 440 and flange 439 relative to each other.
The arrow 443 denotes in FIG. 6 the direction in which the tips of
the radially inwardly extending fingers of the diaphragm spring 412
must be shifted in order to move the radially outermost portion of
the diaphragm spring axially and away from the flywheel 404 in
order to disengage the friction clutch 407. The force which is
applied in the direction of the arrow 443 must overcome the force
with which the prestressed spring 412 urges the pressure plate 408
against the respective friction lining of the clutch disc 409. The
bias of the springs 427, 428 is selected in such a way that the
resulting axial force acting upon the race 418 (namely the
difference between the axially applied larger force of the spring
428 and the axially applied smaller force of the spring 427) is
smaller than the force which must be applied in the direction of
the arrow 443 in order to disengage the clutch 407. This ensures
that the spring 428 ceases to urge the inner race 418 axially
relative to the outer race 416 when the friction clutch 407 is
engaged to transmit torque from the flywheel 404 to the input
element 410 of the change-speed transmission. In other words, the
rolling elements 415a are not clamped between the races 416 and 418
when the flywheels 403, 404 are to transmit torque from the output
element 405 to the input element 410. The just discussed selection
of the bias of the springs 412, 427, 428 and of the force which
must be applied in the direction of the arrow 443 is desirable and
advantageous because this ensures that the rolling elements 415a
come into contact with different portions of the tracks which are
defined by the races 416 and 418 and also that the angular
positions of the rolling elements 415a change with attendant
reduction of pronounced localized wear upon the antifriction
bearing 415 and the longer useful life of the torque transmitting
apparatus 401.
The extent to which the flywheels 403 and 404 can turn relative to
each other is determined by the length of circumferentially
extending slots in the flange 439. Such slots receive portions of
the respective rivets 429.
FIG. 8 shows a portion of a modified torque transmitting apparatus
wherein the dished spring 527 which bears upon the bead 534 reacts
against the corresponding end face of the outer race 516 and urges
the bead 534 against a friction generating washer 503b so that the
latter bears against a shoulder 503a of the flywheel 503. Thus, the
spring 527 is disposed between the median portion or membrane of
the radially extending leg 525b of the ring 525 and the respective
end faces of the races 516 and 518. The washer 503b can be made of
steel and is preferably mounted in such a way that it cannot rotate
relative to the flywheel 503. The construction which is shown in
FIG. 8 ensures that the axially oriented force which is generated
by the spring 527 is added to the axially oriented force which is
generated by the spring 528 so as to urge the inner race 518
axially of the outer race 516 when the friction clutch (not shown
in FIG. 8) is disengaged i.e., the races 516 and 518 then clamp the
rolling elements 515a of the antifriction bearing 515. The leg 525b
is integral with the axially extending annular leg 525a of the ring
525. The ring 526 has an axially extending portion 526a and the
radially extending leg 526b with bead 535. The rings 525, 526 are
installed in the flywheel 504.
An important advantage of the torque transmitting apparatus of
FIGS. 6-8 is that the thermal barrier 424 of FIGS. 6-7 or the
barrier of FIG. 8 can also serve as (or as a component part of) a
means for opposing angular movements of the flywheels 403 and 404
or 503 and 504 relative to each other. This contributes to
simplicity, compactness and lower cost of the apparatus. The rings
425, 426 or 525, 526 and the springs 427, 428 or 527, 528 can
constitute the sole means for frictionally damping the angular
movements of the flywheel 403 or 503 relative to the flywheel 404
or 504 and/or vice versa. This entails a substantial reduction of
the overall number of component parts of the torque transmitting
apparatus and simplifies the assembly and/or dismantling of such
apparatus. If the improved thermal barrier 424 or the barrier of
FIG. 8 constitutes the sole means for functionally damping the
angular movements of the flywheels 403 or 503 and 404 or 504
relative to each other, the conventional damper or dampers can be
omitted in their entirety. On the other hand, if the apparatus
comprises one or more conventional dampers plus the thermal barrier
which also serves as or includes a means for opposing angular
movements of the flywheels 403, 404 or 503, 504 relative to each
other, the damping action can be enhanced by a unit (the improved
torque transmitting apparatus) which also performs another
important, desirable and advantageous (thermal insulating)
function. It has been found that the improved thermal barrier
(either alone or in combination with one or more conventional
dampers) can ensure an ideal or nearly ideal progress of the
damping action. Proper thermal insulation of the lubricant
(normally grease) in the annular space between the races 416, 418
or 516, 518 of the antifriction bearing 415 or 515 contributes
significantly to a longer useful life of the entire apparatus, and
such insulation also reduces the need for frequent inspection of
the bearing. Proper lubrication of the tracks which are defined by
the races 416, 418 or 516, 518 and of the rolling elements 415a or
515a is one of the most important factors insofar as the useful
life of the bearing means (and hence of the entire torque
transmitting apparatus) is concerned.
The apparatus of FIGS. 6-8 can be simplified still further by
omitting the spring 427 and/or 428 of FIGS. 6-7 and/or the spring
527 and/or 528 of FIG. 8. All that is necessary is to ensure that
the rings 425, 426 or 525, 526 are made of a material which
exhibits a requisite degree of springiness so that the radially
extending arms 425b, 426b or 525b, 526b bear against the respective
end faces of the race 418 or 518 and/or directly against the
flywheel 403 and/or against a part (such as 503b) which rotates
with the flywheel 503 when the improved thermal barrier is properly
installed between the friction clutch and the bearing 415 or 515,
normally between the flywheel 404 or 504 and the respective race
(416 or 516) of the bearing means. The utilization of dished
springs or otherwise configurated biasing means is often preferred
because such springs ensure a more predictable generation of
friction between the ring or rings of the thermal barrier and the
flywheel 403 or 503. The springs 427, 428 or FIG. 7 further ensure
an even more reliable sealing of both axial ends of the annular
space which is defined by the races 416, 418 and serves for
reception of the rolling elements 415a.
The improved thermal barrier can operate satisfactorily with a
single ring 425, 525 or 426, 526. The utilization of two rings is
preferred at this time because two rings ensure a more satisfactory
sealing of the aforediscussed annular space between the races 416,
418 or 516, 518, because two rings can establish a highly
satisfactory thermal barrier between the flywheel 404 or 504 and
the bearing 415 o 515, and also because two rings (especially when
used with two discrete dished springs or the like) can provide a
highly satisfactory damping action by opposing the angular
movements of the flywheels 403, 404 or 503, 504 relative to each
other.
FIGS. 9 and 10 show an apparatus 601 for controlled transmission of
torque from the crankshaft 605 (indicated by phantom lines) of the
internal combustion engine to the input shaft 610 (shown by phantom
lines) of the change-speed transmission in a motor vehicle. The
apparatus 601 comprises a composite flywheel 602 including coaxial
first and second components 603, 604 which are rotatable relative
to each other within predetermined limits. The component 603 is
coaxially secured to the crankshaft 605 by a set of bolts 606, and
the component 604 carries the housing or cover 611 of a friction
clutch 607 whose clutch disc or clutch plate 609 has a hub which is
non-rotatably secured to the input shaft 610. The component 603
drives the input shaft 610 in response to engagement of the clutch
607 in a manner not forming part of the present invention. FIG. 9
shows an axially movable pressure plate 608 which is normally
biased toward the component 604 by a diaphragm spring 612 tiltably
mounted at the inner side of the housing 611. The clutch plate 609
carries linings which are in frictional engagement with the
adjacent surface of the pressure plate 608 and with an annular
friction surface 604a of the component 604 when the clutch 607 is
engaged, namely when the component 603 drives the input shaft 610
through the medium of the component 604 and clutch plate 609.
The apparatus 601 further comprises means for yieldably opposing
angular movements of the components 603 and 604 relative to each
other. Such opposing means comprises a first damping unit 613, a
second damping unit 614 in series with the unit 613, and a friction
generating device 613a. The exact construction of the units 613,
614 and friction generating device 613a forms no part of the
present invention. Reference may be had to the aforementioned
copending applications of the assignee and to the embodiments of
FIGS. 1-8.
The apparatus 601 still further comprises bearing means 615
including at least one radial antifriction bearing 616 having an
outer race 617, an inner race 619 and an annulus of spherical
rolling elements 616a between the two races. The outer race 617 is
disposed in an axial recess or bore 618 of the component 604, and
the inner race 619 is preferably a press-fit on a centrally located
cylindrical protuberance 620 of the component 603. The protuberance
620 extends axially in a direction away from the crankshaft 605 and
into the bore 618 of the component 604. The inner race 619 abuts a
stop in the form of a shoulder 621 of the protuberance 620 and is
held against axial movement away from such shoulder by a
disc-shaped retainer 622 which is secured to the adjacent end face
620a of the protuberance 620 by a set of screws 623 or other
suitable fasteners.
The apparatus 601 also comprises a number of means for impeding or
preventing the transmission of heat between the friction surface
604a and the radial antifriction bearing 616. The latter is
disposed radially inwardly of the friction linings on the clutch
plate 609. One of the heat transmission preventing or impeding
means comprises a thermal barrier 624 composed of two coaxial rings
625 and 626 each having a substantially L-shaped cross-sectional
outline. The axially extending (cylindrical) portions 625a, 626a of
the rings 625, 626 surround the major part of the external surface
of the outer race 617 and are received in the bore 618 of the
second component 604. The radially extending (washer-like) portions
625b, 626b of the rings 625, 626 are adjacent the respective end
faces of the races 617, 619 and are biased against the
corresponding end faces of the inner race 619 by energy storing
elements in the form of diaphragm springs 627, 628, respectively.
The radially extending portions 625b, 626b not only intercept some
of the heat but also serve to seal the space between the races 617,
619 so as to prevent uncontrolled escape of grease for the rolling
elements 616a. The radially outermost portion of the diaphragm
spring 627 reacts against a shoulder of a disc 630 which is affixed
to the component 604 by rivets 629, and the radially innermost
portion of the spring 627 bears against the radially innermost part
of the portion 625b. The diaphragm spring 628 has a radially
outermost portion which reacts against an internal shoulder of the
component 604 and a radially innermost portion which bears against
the radially innermost part of the portion 626b. The diameter of
the surface surrounding the bore 618 is sufficiently large to allow
for the placing of rings 625, 626 onto the outer race 617 in a
manner as shown in FIG. 9. The material of the rings 625, 626 is
selected in such a way that they constitute a thermal insulator
which impedes the transfer of heat between the friction surface
604a of the component 604 and the radial bearing 616. The bearing
616 is held against axial movement relative to the component 604 by
the rings 625, 626 in that the ring 625 abuts the disc 630 and the
ring 626 abuts an internal shoulder 631 of the component 604. As
mentioned before, the rivets 629 fix the disc 630 to the component
604.
The damping unit 613 comprises the aforementioned disc 630 and a
second disc 633. The discs 630, 633 are disposed at the opposite
sides of a flange 632 and are held (by the rivets 629) against
axial movement relative to each other and relative to the component
604. The flange 632 has windows (not specifically referenced) which
register with windows in the discs 630, 633 and serve to receive
energy storing elements in the form of coil springs 634. The coil
springs 634 yieldably oppose angular movements of the flange 631
and discs 630, 633 relative to each other. The flange 632 is
rotatable relative to the component 604, together with the
component 603.
The friction generating device 613a can be said to constitute a
part of the damping unit 613 and is designed to resist each and
every angular movement of the components 603 and 604 relative to
each other. This friction generating device is installed between
the disc 630 and the component 603 and comprises an energy storing
device in the form of a diaphragm spring 635 which reacts against
the disc 630 and bears upon a ring 636. The ring 636, in turn,
urges a washer 637 against the component 603. The force which is
transmitted by the diaphragm spring 635 to the disc 630 is taken up
by the radial bearing 616.
The flange 632 is the input member of the damping unit 613 as well
as the output member of the damping unit 614. The input member of
the damping unit 614 includes two axially spaced-apart discs 638,
639 which are non-rotatably secured to the component 603. The disc
639 is affixed to the component 603 by rivets 640. The periphery of
the disc 638 is provided with integral projections in the form of
axially extending lugs 638a which extend into complementary
recesses 641 of the disc 639. This ensures that the discs 638, 639
can move axially toward and away from each other but cannot perform
any angular movements with respect to one another. The flange 632
has radially extending arms or teeth 642 which are clamped between
the discs 638 and 639. For this purpose, the discs 638, 639 are
biased toward each other by a diaphragm spring 643. The spring 643
reacts against the component 603 and bears upon the disc 638 in a
direction to urge the disc 638 toward the disc 639. The discs 638,
639 have windows which register with each other and with tooth
spaces between the arms 642 and serve to receive energy storing
elements in the form of coil springs 644.
In accordance with a feature of the invention which is shown in
FIGS. 9 and 10, the component 604 is provided with axially
extending passages 645 which are disposed between the bore 618 for
the radial bearing 616 and the friction surface 604a of the
component 604, as considered in the radial direction of the
composite flywheel 602. The passages 645 serve to prevent the
transfer of substantial quantities of heat from the friction
surface 604a of the component 604 to the bearing 616. As can be
seen in FIG. 10, the passages 645 can constitute slots which are
elongated in the circumferential direction of the component 604 and
together form an annulus whose diameter 650 is smaller than the
minimum diameter of the friction surface 604a but greater than the
diameter of the surface surrounding the bore 618 of the component
604. The passages 645 are preferably adjacent, and most preferably
closely adjacent, the bearing 616.
In accordance with a presently preferred embodiment of the
invention, the cross-sectional areas of the passages 645 increase
in a direction from a surface 646 radially inwardly of the friction
surface 604a toward an additional surface 647 of the component 604
opposite the friction surface 604a. The surface 647 faces the
damping units 613 and 614. The component 604 has internal surfaces
which surround the passages 645 and each of which includes a first
or inner portion 648 nearer to the common axis of the components
603, 604 and extending in at least substantial parallelism with
such axis, and a second or outer portion 649 which is more distant
from the common axis of the components 603, 604 and diverges
radially outwardly away from the common axis toward the periphery
of the component 604. At least a portion of each surface portion
649 has a substantially convex outline as can be readily seen in
the lower portion of FIG. 9. The shallow leftmost portion of each
passage 645 is provided in the second surface 647 of the component
604 and extends radially at least along a portion (x) of the width
of the friction surface 604a as considered in the radial direction
of the flywheel 602. The surfaces bounding the passages 645
resemble those of air circulating vanes or blades on an air
impeller and cause streams of air to flow through the passages 645
in a direction from the friction surface 604a toward the additional
surface 647 of the component 604. This entails a pronounced cooling
of the entire flywheel 602 and greatly reduces the amount of heat
which is transmitted from the friction surface 604a to the bearing
616. Thus, that portion of the component 604 which is formed with
the passages 645 can be said to constitute a thermal barrier which
impedes the transfer of heat from the surface 604a to the
antifriction bearing 616. In addition, streams of air flowing
through the passages 645 effect a substantial cooling of component
parts of the damping means 613, 614, 613a because such streams flow
along the discs 633 and 639 and a portion of each such stream can
escape, for example, through the windows of the discs 630, 633 and
flange 632. As mentioned before, such windows are provided for the
energy storing springs 634.
FIG. 10 shows that the rivets 629 form an annulus whose diameter
equals or approximates the diameter 650 of the circle formed by the
annulus of passages 645. FIG. 10 further shows that each fastener
629 alternates with pairs of slit-shaped passages 645 which have
identical lengths. The length of each of the webs 652 through which
the fasteners 629 extend exceeds the length of a passage 645. For
example, the length of a web 652 (as measured in the
circumferential direction of the component 604) can be between 0.5
and 2.5 times the length of a passage 645. In the embodiment which
is shown in FIGS. 9 and 10, the component 604 is provided with two
sets of webs, namely the aforementioned relatively long webs 652
which carry the rivets 629 and shorter webs 651 which alternate
with the longer webs 652. Any heat which is generated at the
friction surface 604a and is to reach the antifriction bearing 616
must be transmitted through the webs 651 and 652. Such webs can be
said to constitute small heat barriers because they are being
cooled by streams of air flowing through the passages 645. That
(innermost) portion of the component 604 which defines the bore 618
and surrounds the radial bearing 616 is denoted by the character
653. The portion 653 is surrounded by the annulus of passages 645
and by the webs 651 and 652 of the component 604. The length of a
web 652 can equal or approximate the combined length of two shorter
webs 651 (as measured in the circumferential direction of the
radially innermost portion 653 of the component 604). The length of
a passage 645 can equal or exceed (at least slightly) the length of
a shorter web 651.
The combined length of the passages 645 (in the circumferential
direction of the component 604) can be between 20 and 70% of the
total length of the corresponding portion of the component 604. In
the embodiment of FIGS. 9 and 10, the combined length of the
passages 645 can be at least 50% of the circumferential length of
the corresponding portion of the component 604. In other words, at
least one-half of the circle whose diameter is shown at 650 can
extend through the passages 645.
It is also within the purview of the invention to increase the
length of the passages 645. For example, if the radial bearing 616
can stand reasonably pronounced thermal stresses, or if the
transmission of pronounced thermal stresses is impeded in another
way, the length of the illustrated passages 645 can be increased as
shown in FIG. 10 at 654, i.e., the shorter webs 651 can be omitted
so that the rivets 629 alternate with relatively long passages each
of which can extend along an arc in excess of 45 degrees. For
example, the component 604 can be provided with four relatively
long passages 645 which alternate with four webs 652, and each web
652 is traversed by at least one fastener in the form of a rivet
629.
Since the webs 651 and/or 652 constitute relatively narrow portions
of the component 604 and alternate with passages 645, they act not
unlike restrictors or throttles to the transmission of heat from
the friction surface 604a toward the bearing 616. Thus, the
corresponding portion of the component 604 is cooled by streams of
air flowing through the passages 645, and the webs 652 constitute
restrictors in that they oppose the transmission of heat to the
radial bearing 616 so that the useful life of such bearing is much
longer than in conventional apparatus. In view of the
aforediscussed distribution of material of the component 604 in the
region of the circle whose diameter is shown at 650, and in view of
the distribution of passages 645 in the form of an annulus which is
disposed between the friction surface 604a and the radially
innermost portion 653 of the component 604 (i.e., radially
outwardly of the bearing 616), heat which is generated in response
to engagement of the friction clutch 607 can entail some rise in
the temperature of the radially innermost portion 653 but not to a
value which could entail damage to the bearing 616. The feature
that the bearing 616 is not subjected to excessive thermal stresses
is attributable, to a considerable extent, to the fact that the
major part of the mass of the component 604 is located radially
outwardly of the passages 645.
The placing of rivets 629 into the webs 652 exhibits the advantage
that the rivets dissipate substantial quantities of heat which
would otherwise pass through the webs 652 and into the radially
innermost portion 653 of the component 604. Moreover, the rivets
629 transmit heat to the discs 630, 633 which dissipate such heat
into the surrounding atmosphere. In other words, the rivets 629
ensure that a substantial percentage of heat which would have
passed through the webs 652 and into the portion 653 is transmitted
to parts (630, 633) having large exposed surfaces to ensure rapid
dissipation of transmitted heat to atmospheric air.
The heat barrier 624 including the rings 625, 626 constitutes an
optional feature of the apparatus of FIGS. 9-10. Thus, if the
bearing 616 is furnished with conventional sealing rings, the rings
625, 626 can be omitted and the bearing 616 can be fully assembled
on the component 603 before the component 603 is assembled with the
component 604. In such apparatus, the outer race 617 of the bearing
616 is or can be a press-fit in the bore 618 of the component 604.
The just described mounting of the bearing 616 in the bore 618
(without the rings 625, 626) reduces the initial cost and
simplifies the assembly of the apparatus 601.
The passages 645 are provided in addition to those passages which
are desirable or necessary in the component 604 for other purposes,
for example, to facilitate assembly of the apparatus 601 by
providing paths for the tool which is to rotate the bolts 605
and/or other tools. It is also known to provide the components of a
composite flywheel with openings for withdrawal of lubricant and
for other purposes. The passages 645 are provided for the specific
purpose of reducing the transfer of heat between the antifriction
bearing which is interposed between the components of the flywheel
and the friction surface of the component which comes into contact
with the linings of the clutch plate 609. The passages 645 extend
all the way between the surfaces 604a and 647 of the component 604
so as to ensure the aforedescribed desirable circulation of air
streams and attendant cooling of the corresponding portion of the
component 604 radially outwardly of the portion 653 which supports
and surrounds the outer race 617 of the antifriction bearing 616.
It has been found that the passages 645 contribute significantly to
the useful life of the bearing 616 because the bearing is shielded
from excessive thermal stresses which develop when the friction
clutch 607 is actuated and which are likely to rapidly destroy the
bearing in the absence of any remedial measures in addition to
those which are already known in the art. The provision of passages
645 is particularly desirable in apparatus which employ
antifriction bearings whose components are assembled with a minimum
of play so that pronounced and rapid heating or cooling of such
bearings could entail extensive thermally induced distortion and
attendant jamming of the parts. In fact, such excessive thermally
induced distortion can lead to seizing with immediate destruction
of the bearing. The streams of air which flow through the passages
645 further ensure adequate cooling of lubricant for the rolling
elements 616a of the bearing 616 regardless of whether such
lubricant is oil or grease. Adequate cooling (or prevention of
overheating) of the lubricant also prolongs the useful life of the
bearing 616.
The passages 645 can be configurated in a number of different ways
without departing from the spirit of the invention. It has been
found that elongated passages in the form of arcuate slots are
particularly advantageous because they ensure the flow of large
quantities of air and reduce the combined length of webs 652 or
webs 651, 652. The aforedescribed configuration of surfaces 648,
649 which surround the passages 645 is desirable and advantageous
because such surfaces act not unlike the surfaces of vanes or
blades and ensure forced circulation of air in the region of the
circle including the diameter 650. The placing of passages 645
close to the radially innermost portion 653 of the component 604
also contributes to a more reliable prevention of overheating of
the bearing 616. The provision of relatively shallow recesses which
are provided in the surface 647 and constitute the radially
outermost portions of the passages 645 ensures that a large
percentage of air which is heated during flow through the passages
is caused to flow radially outwardly and away from the bearing 616.
The surfaces surrounding the passages can be said to constitute a
radial fan which draws air from the space radially inwardly of the
friction surface 604a and causes streams of air to flow first
axially and thereupon radially outwardly toward the periphery of
the component 604. This effectively reduces the likelihood of flow
of large quantities of heated air toward the bearing 616. The
aforementioned configuration (convexity) of the surface portions
649 in the passages 645 also contributes to a desirable flow of
heated air radially outwardly and away from the radially innermost
portion 653.
While it is possible to provide the passages 645 in non-uniform or
irregular distribution, a uniform or regular distribution is
preferred at this time because it ensures predictable cooling of
each and every portion of the component 604 in the region of the
webs 651 and 652.
As mentioned before, the mass of the component 604 radially
outwardly of the passages 645 is much larger than the mass of the
radially innermost portion 653. Since the flow of heated air is
radially outwardly, eventual heating of the major part of the
component 604 radially outwardly of the passages 645 does not
entail an overheating of the portion 653 and bearing 616.
The streams of air which flow through the passages 645 bring about
a desirable cooling of the elements of the damping means 613, 613a,
614. This prolongs the useful life of such damping means and hence
the useful life of the entire apparatus. Moreover, the streams of
air can adequately cool the first component 603 of the composite
flywheel 602.
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can, by applying current
knowledge, readily adapt it for various applications without
omitting features that, from the standpoint of prior art, fairly
constitute essential characteristics of the generic and specific
aspects of our contribution to the art and, therefore, such
adaptations should and are intended to be comprehended within the
meaning and range of equivalence of the appended claims.
* * * * *