Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to a transmission to couple
a vehlcle engine with the vehicle drive wheels, in particular
the transmission disclosed herein combi.nes a torque converter
with a plurality o~ planetary gear arrangements to provlde
a large number o~ gear ratios.
Transmission o~ power ~rom a vehicle engine ~o the
vehicle wheels ldeallg will allow the vehlcle engine to operate
at or near a most e~icient constan~ speed throughou~ the complete
range o~ vehicle speedsO From a practical standpoint this
goal is una~tainable in vlew o~ the ~act that the vehicle
must be started ~rom a standing positlon. ~urthermoxe, while
using a geared transmission, engine speed must vary throughout
the range o~ the particular gear set engaged~ The u~ zation
~ a torque converter helps to overcome problems o~ ~nitial
start-up and ~urther provldes a br~ader torque transmiss~Dn range;
however~ .~luid drive ~ relatively less e~iclent than a
mechanlcal dr-lve. A mechanlcal drive~ although more e~icient
than a ~luld drlve~ requires a relatively high number o~ gear
ratios in order to allow the engine to operate in its most
e~flcient speed range~ ~lowever~ in adding more gear ratlos,
ef~iciency is sacri~iced through ~riction losses and the like
i~ lnactive gear ratios. ~ccordin~ly~ compromise transmissions
incorporatlng ~eatures of a ~luid drlve or torque converter and
.
a mechanical transmlssion have been designed to take advantage
o.~ the beet characteristics o~ ho~h tran5missionsO
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A problem encountered ;n the design and construc~ion of xuch combi-
nation transmissions is the attainment of uni~orm step ratios betwcen thc
mechanical shifts. Uniform step ratios are ideally most efficient in such
transmissions, as such uniform step ratios eliminate less efficient matches
between engine speeds and desired vehicle speed inherent in a transmission
which couples lar~e step ratios with smaller step ratios.
An example of a combination torque converter and planetary gear
arrangement is found in lJnited States Patent 3,347,113 issued to Ramsel on
October 17, 1967. Ramsel~s patent, which was designed for use in scrapers
of the kind used in earth-moving operations, provides six forward speed ratios
of mechanical drive at high ground speeds while allowing for a fluid drive
at lower ground speeds. Such fluid drive in lower speeds has been found
acceptable in scraper operations. Although Ramsel's patent approaches a
uniform step ratio, there still remain certain uneven steps. In order to
provide more efficient operation at lower speeds required for other types of
vehicles, either additional mechanical gear sets mus~ be provided or the
arrangement of ~he various planetary units and the sizing of the planetary
elements must be modified to provide cons~ant step ratios throughout a
broad range of output speeds.
Summary of the Invention
In accordance with the invention, there is provided a transmission
comprising an input member; a d'r;ven member; a torque converter driven by the
input member; a flrst planetary gear assembly including a firs~ sun gear, a ~'~
plurality of first planet gears, and a first ring gear which is conn0cted to
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~ the torque converter to be driven thereby; a clutch selectively engageable
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for transmi~ting ~orque applied to the inpu~ member directly to the first
planetary ring gear; a second planetary gear assembly including a second sun ~ -
~ gear which is constrained ~o rota~e wi~h the first sun gear of tlle firs~
;~ planetary gear assembly, a second plane~ gear arrangement, and a second ring
gear; a common planet carrier having rotatingly mounted thereupon the first
planet gears and the second planet gear arrange~ent, the common planet carrier
driving the driYen member; first brake means selectively actua'ble for stopping '
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rotation of the second ring gear so ~hat the first planetary gear assembly
and the second planetary gear arrangement operate in a split-torque r01ation-
ship transmitting torque applied to the first ring gear from the input member
to the driven member through the common planet carr;er; second hrake means
selectively actuable for stopping rotation of the first an<l second sun gears
so that torque applied to the first ring gear is transmitted to the driven
member through the common planet carrier; and a second clutch selectively
engageable for drivingly connecting the input member directly with the common
planet carrier and driven member so that the driven member is driven at a
speed of rotation equal to the speed of rota~ion of the input memher.
As will be described this provides the basic component for a ~
transmission for a vehicle utilizing four planetary gear sets to provide :
seven output ratios in t~e highly efficient mechanical range ~ h almost
identical step ratios throughout a broad range of output speeds. The torque ~ :
converter is provided for operation primarily in the first range but also
available in any one of the speed ratios, while a fifth planetary arrange- :~
ment provides a reverse drive.
Brief Descrip~ion of the Drawings :
In the accompanying drawings:
Pigure 1 is a schematic diagram of a transmission embodying the
invention;
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Fig. 2 is a chart showing the particular clutches
and brakes which are engaged in a particular embodiment of
the transmission of Fig. 1 to establish the different drive
ra-tios provided therein, and which shows the speed reductions,
along with the step ratios associated with the speed reductions.
Fig. 3 is a graphical depiction of transmission input
horsepower plotted against transmission output speed, and
Fig. 4 depicts a transmission partly sectionalized
incorporating the provisions of this invention and showing -the
various gearing, clutching and braking elements.
Detailed Description of the Preferred Embodiment
Referring to Fig. 1, a transmission 10 is shown
schematically. Input to the transmission 10 is provided by
shaft 12 driving a speed unit 14 which provides a plurality
of reduction ratios and is comprised of a first planetary
gear arrangement 16 and a second planetary gear arrangement
18. First planetary gear arrangement 16, driven by input
shaft 12, is comprised of a ring gear 16R in intermeshing
relationship with a plurality of the first planet gears 16P,
which in turn are in intermeshing rela-tionship with a first
`sun gear 16S. Ring gear 16R is drivingly connected to input
shaft 12. Second planetary gear arrangement 18 is comprised
of a ring gear 18R, a plurality of intermediate planet gears
18X, a plurality of second planet gears 18P and a sun gear
18S. Sun gear 18S intermeshes with the plurality of inter-
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~'mediate planet gears ~ff~ which intermesh with the plurality
of planet gears 18P, while planet gears 18P intermesh with
ring gear 18R. A common plane-t carrier 20 has mounted
thereon the plurality of first planet gears 16P and a~ially
separated, but immediately adjacent thereto, in-termediate
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planet gears 18X along with planet gears l~P. F'irst sun
gear 16S and second sun gear 18S are integrally formed on
a coaxial shaft 22 mounted about sha~t 12 to enable ~irst
sun gear 16S and second sun gear 18S to rotate together as
a unit. A clutch means 28 is provided to directly interconnect
input shaft 12 with common carrier 20~ common carrier 20
providing input to a range unit 30 by means of a sha~t 32.
Coaxial shaft 22 is also provided with a b:rake means 2~
allowing selective stopping of rotation o~ sun gears 16S and
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18$ to provic3e a mid-range range output .rom planetar~ gear
- arrangement 16 to common carrier 200 Second r~ng gear lgR ls
provlded with a brake means 26 aLlowing ~3e~ective stopping o~
rota~:ion o~ ring gear 18R to provlde a low-rangc spl-lt~torque
output ~rom planetary gear arrangemen~s 16 an~ 18 to common
carrier~ 20.
Range unit 30 provides additional reductivn ratlos
and is compr~sed o~ a pair o~ plane~ary gear arrangements 34 and
36. Mid~range planetary gear arrangement 34 has a mld-Yange
sun gear 34S drivingly connected to sha~t 32 while low xange
planekar~ gear arrangemen~ 36 has a low range sun gear 36S similarly
drlvingly connected to sha~t 32, Mid range planetary gear
arrangement 34 lncluces a pluralit~ of mid-range planet gears 3L~p
in intermeshing relationship with mid-range sun gear 34S~ and
a mid-range ring gear 34R in intermeshing relationshlp with the
plurallty of mid~-range planet gears 34P0 A bra~e means 38 is
provided for selectively stQpping ~rotation o~ mid-range ring
gear 3~R~ A clutch means ~0 selectively interconnects sha~t
32 wlth the pluraliky o~ mid-range planet gears 34P through
a mld-range planet carrier 420 Mid-range planet carrler
~2 is drivingly lnterconnected with low range ring gear 36R o~
lo~ range planetar~ gear arrangement 36~ Low range ring gear
36R is provided with a brake means 4~ to allow selective stoppîng
o~ rotation o~ low range ring gear 36R. A plurality o~ low range
planet gears 36P completes low range planetary gear arrangement
36~ the plurality o~ low range planet gears 36P lntermeshing
with low range sun gear 36S and also intermeshing wi'h low range
ring gear 3~R. The pluralit~ o~ low range planet gears 36P ar~
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rotatingl~ mounted on a low range planet carrier 46 which is
drivingly connected to an output sha~t 48.
Range unit 30 is sized so thak actuation oL` brake
means 1~4 to stop rotation of ring gear 36R provides a low range
reducti.on in range unlt 30 with output torque delivered ~rom
plane~ carrier 46 to output sha~t 48. Actuaklon o~ brake means
38 to stop rotation o~ ring gear 34R provides a mid~range reduction
ln range unit 30 w~th output torque delivered through planet carrier
42 ~o ring gear 36R thence planet gears 36P to planet carrier 46
and output sha~t 48O Engagement of clutch means 40 without
actuation of either brake means 24 or 26 or clutch means 2~ ~ .
o~ speed unit 1~ provides a neutral range with no transmisslon
o~ torque, such torque transmitted to ring gear 16 b~ lnput
sha~t 12 being dissipated in speed unit 11~ However, e~gagement
o~ clutch means ~0 with an actuated drive engaging device in
speed unit 14 results in ca~rrier 42 rotatirlg xing gear 36R
at the same speed and in the same d~rectlon as sun gear 36S
thus rotatlng planet carrier 46 to transmit tcrque to output
sha~ 489
A reverse drive planetary unit 50~ to provide selective
reverse rotatlon of output sha~t ~8, is coaxially mounted about
output sha~t 48 and is drivingly connected ~o low range ring
gear 36R by means o~ a coaxial shaft 52. Reverse planetar~ unit
50 is comprised o~ a sun gear 50S drivingly mounte~ on coaxial
sha~t 52 and in inter~eshing relationship with a plurality o~
reverse planet gears 50P rotatingly mounted on a reverse
planet carr~er 56. The pluralit~ o~ reverse planet gears 50P
intermesh with a reverse ring gear 50~ o~ reverse planetar~
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uni~ 50. A brake means 54 is provided to selectively s~op
rotation of reverse rlng gear 50R and ~hus prov:lcle outpu~ tu
sha~t 48 through reverse planet carrler 56 which ls ~riv:lngly
connected to output sha~t 1~83 such ou~put ~,eing available
onl~ while clutch means 2S is engaged or al,ternatively while
e:Lther brake means 21~ or 26 is actuated.
Input sha~t 12 has mounted ~hereon a drive gea.r 58
whlch may be driven alternatlvely by the output o~ a conven~ional
torque converter 60 to pxovide a fluid drive or directly by
a prlme mover~ Tor~ue converter 60 has a pump element 62 inter- -
connected with an output sha~t 64 o~ an engine (not shown). The
turbine element 66 o~ tor~ue converter 60 is drivingly connected
'GO a turbine sha~t 68 which is prov:ided wi~h a un-lversal ~oint
69 and has mounted thereon a drive gear 70 intermeshing wlth
drive gear 58. Reaction element 72 is provide~ with a conventional
overrunning clutch 74 associated with a stationary structure 76
such as the transmission housing assembly. ~ drive engaæement
means 65 is included~ interconnecting engine output shaf~ 64
directly to turbine sha~t 68~ thereb~ providlng a direct drive
~rom the engine (not shown) to drive gear 700
~Iaving generall~ descr.ibed the schematlc arrangement
o~ the transmlssion3 reference is made to Figure 2 ~or discussion
o~ the varlous speed reduction and range reduction ratios with
appropriate clu~ches and brakes engagedO The transm~ssion as ,.,'.
:25 described above provides ~or a possible nine forward speeds '~ :
by selection o~ a brake or clutch unit in range unit 30 and :~
selection of a b.rake or clutch in speed unit 140 In practice~ ~
however~ it has been determined that seven reduction ra~ios are ,
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; su~ficient to serve the needs o~ most transmisslons, In khe
embodiment discussed herein khe primary obJective is to provlde
a kransmission which has a uni~orm step ratio over the seven
speeds. A second objective o~ khis kransmission is to provide
a minimum Or clutch changes between the various output ra~es.
These two objeckives are attained in this transmlssion in the
three lowest ranges by actuating bral~e 44 of range unit 30 coupled
with actuation of brake 26 ~or a ~irst rangeJ brake 24 ~or a seconcl
range and clutch 28 ~or a third range.
The unlque arrangement o~ speed unit 14 is such that
ln the ~irst range forward when brake 26 is energlzed, khe two
planetary gear arrangements 16 and 18 provide a spli~-t~rque
' oukput. Split torque ls available to CQmmon carrier 20 ~rom
j ~irst planet gear 16P in planetary gear arrangemant 16 and
planet gears 18P and l~X ln planetary gear arrangement 18.
Particular selection of appropriate gearing in the planetar~
gear arrangements ma~ provlde a reduction ratio of 1.84 in the
speed unit as shown in Fig. 20 AS noted above~ input ko speed
unik 14 is at rlng gear 16Ro The planetary gear arrangements
o~ range unit 30 may be proportioned so thak actuation o~' brake
26 ln speed unit 14 and brake 44 ln range unit 30 in the transmission
herein described provides an overall reduc-tion o~ 6.083 t,he range
unit reduction ln low range planetary gear arrangement 36 being
adapted ~o provide a reduction of 3,31 coupled with the a~oresald
ratlo o~ 1~84 in ~he speed UnitD In ~he same application~
actuation o~ brake 24 while maintaining brake 44 in an actuated
state may provide a total reduction ratio o~ 4O4 with this con~
~lguration the reduction available ~n the speed unit being 1.35.
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Deactivation of brake 2~ ancl actuation o~ clu~ch 28 prov;~es a
st.raight through drlve ln the speed unit with no rcductlon and
thereby the total reduction of the ~ransmisslon .ls dependent
upon low range planetary gear arrangement 36 or 3~31. It is
emphasized that in all three o~ these low :range ratlos, bral~e 41
remains actuated with shl~ts occurring only as a result o~
actuation o~ the brakes or clutch in speed unit 14D
To shi~t to a ~ourth range forward;, brake 44 i.s
deactùated and brake 38 is actuated both belng in range unit
30/ along w~th brake 24 in speed unit 14~ the speed unit providing
a reduction o~ 1.34 and the range unit providing a reduction
of 1.83 for a total reduction o~ 2.4~ Deactuation o~ brake 24
and engagement o~ clutch 28 whlle retaln:lng brake 38 in an
actuated state provides a ri~th range ~orward with the ratios as
lllustrated in FICT~ 2~ ~ sixth range ~orward is pro~ided by
actuation o~ brake 24 and engagement o~ clu~ch 40, ~hile a seventh ;~
range is provided by engagement o~ the two clutches 28 and 40
thereby providing a straight through drive with no reduction.
It is speciflcally pointed out that by proper propor-
~ionlng o~ the various planetary gear arrangements to provide
the con~iguration shown ln FICTO 2, the step ratlo between the
varlous reduction ratios is practically constant at 1035, varying
to 1034 only between the third and ~ourth ratios~ whlch is
one o~ the prime object-ives o~ the transmission~ ~n additlonal
~ a~ure o~ this transmission is, as no~ed above, that during the ~;
~irst three shi~ts only one drive engagement means is involved,
brake 44 remaining actuated throughout these three shi~ts, and
~or the entlre seven ranges a total o~ ten changes in drive
engagement means occursO
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Although three reverse ranges are theoreticall~
possible by combining brake 24 or b.rake 2S or clutch 28 with
brake 54, it has been determined that proper ratloint~ o~
reverse planetar~ gear unit 50 provld~s an adecluate reverse
range unit reduction, thus the speed unit reduction capabillty
ls not utilized in the reverse mode ot operation~
Re~erring to FIGo 3~ the specific advantages o~
the constant or nearl~ constant step ratios between shi~ts
become apparent when compared with earlier transmissions o~
multiple drive ratlos. FIG 3 shows graphically the input
horsepower plotted against output speed both in percent of
maximumO It is evident that once a 10% maximum output speed
is achieved, the step ra~ios o~ the various mechanical drives
are then evelg spaced providing a utilizat~on approaching 100%
o~ input horsepower at the peak o~ each drive ratio and ensuring
the most ef~icient part o~ each drive ratio~ ~hat is~ the upper
portion o~ the curves~ is ~ully utilizedO Comparlson wi~h earlier
transmisslons show uneven peaks and valle~s as compared ~o ~he :~
present inventionO
~eferring to FIGo 4J mechanical constructlon o~ a
pre~erred embodiment is 111ustrated partly in cross section.
The torque converter 60, illustrated in FIG~ 1 schema~ically,
has not been included in FIGo 4 as such torque converters are
~ell kno~n in the art0 In the ernbodiment envlsioned in FIG~ 4
a torque converter of the type set ~orth in U~S ~atent 3,347,113
issued to Ramsel on October 17, 1967 would be applicable to this
inventionO I~ is emphasized~ however~ that the torq~e converter
utilized ln U,SO Pa~ent 3g34~,113 is not provided with a drive
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engagement means analogous to drive engagement means 65 shown
schematically ln FIG, l and interconnecting output shart 6I~ of
the engine (not shown) to turbine sha~t 68~ Re~erring again to
FI~. 4, drive gear 58 is shown splLned to sha~t 12, shaft 12
drivlng ring gear 16R ~hrough drive ~lange 90 by means o.~ spline
connection 78. Coaxial sha~t 22, which has integrally formed there-
with ~irst sun gear 15S and second sun gear 18S3 has mounted thereon
the rotating member 25 o~ bra~e means 24~ bra~e means 24 being
of a conventional lnterleaved disc type~ by a spllne 80~ Rotating
member 25 is provlded wlth a bearing 82 to provide ~ree rotation .
o.~ rotating member 25 ln the transmlssion houslng. Co~mon planet
carrler 20, in the ll~ustrated embodiment, substantially encompasses
~irst planetary gear arrangement 16 and is interconnected to
: sha~t 32 by a spline connection 840 Clutch means 28~ which
selectivelg interconnects shaft 12 with common planet carrier 20,
is similarly substantially encompassed by common plane~ carrier 20.
Clutch means 28 is o~ the conventional rotating interleaved disc : -
tgpe and is provided with resllient means 86 which mag be a spring
o~ the ~elleville-type urging clutch means 28 to the disengaged
stateO Common planet carrier 20 is rotatingly mo~mted bg bearing -~
means 88 d~sposed between common planet carrier 20 and drlve
~lange 90 with drlve ~lange 90 driving ~lrst ring gear 16Ro
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Second bearing means 92 is provided at the opposite end of~common
planet carrier and is disposed between rotatlng member 25 o~ :~
brake means 249 which may also be o~ the interleaved disc tgpe,
and common planet carrler 20. A thlrd bearing means 94 is disposed
between common planet carrler 20 and portion 96 o~ the transmlssion
houslng whlch ~orms a separation between speed UIlit 14 and range
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unit 30, Bearing meàns 9~ ~ovIdes ror rota~ion o.f common planet
carrier 20 and sha.~'t 32.
Range unit 30~ as noted above in -~,he discussion relatlr~
to ~IG. 1, provides output through plallct carriar 46 to out~ut
sha~t 48 which is coax~ally mounted about s~la~t 3~0 ~ bearing
means 98 allows free rotatlon of output sha~t 48 about s~la~t
32. Reverse planet carrler 56 is splined to output sha~t
4~ by spline connec~ion 99, and ma~ have integrally ~ormed there~
with an output spline 101. Planetarg units 34 and 36 are mounted
about sha~t 32 with sun gears 34S and 36S splined theretoO
Sun gear 34S which is splined to shaft 32 has extending
outwardlg thererrom a M ange lQ3 wlth which clutch means 40 is
assoclated. Engagement o~ clutch means 40 therefore associates
sha~t 32 through sun gear 34S with planet carrier 42 o:~ range
unit 30. A bearing means 105 is provlded between planet carrier
42 and porkion 96 o~ the transmisslon housing wh~ch along wi~h
a bearing means 107 located on the opposite side o~ sun ~ear
34S allows free rotation o~ planet carrier 42. Brake means 38
and brake means 44 mag be o~ the interleaved disc type and are
associated wi~h the transmission housing to stop rotation of rlng
gears 34R and 36R respectively~
Operation of the preferred embodiment should be
evident from the discussion o~ the structure above; however,
certaln points of operation are herein reiterated~ Initiall~ :
it is pointed out that the transmission mag be operated with
the torque converter provlding input to drive gear 58 or b~ a
direct connection between engine output shaft 64 and drive gear
58, bg engagement o~ clutch 65~ Other than operatlon in ~irst
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range forward and seventh range ~orward, the transtnlssio~ til:lzes
one or two planetary gear arrangements to accomplish the necessary
reductionO In the ~irst range ~orward, a split torque output
is provided by engagement of brake means 26 and bra}ce means 44.
Thus ~irst planetary gear arrangement 16 ancl second plane~ary
~ gear arrangement 18 combine to provide output torque to shaft
; 32 which in turn drives low range planetary gear arrangement 36
through sun gear 36S. In the seventh range ~orward, engagement
o~ clutch 28 and clutch 40 provicles a direct drive through both
~he speed unit 14 and range unit 30 to output sha~ 48~
While the lnvention has been describec1 with respect
to a single embodiment, it wi.ll be apparent ~hat many modi.~ications
are posslble and it is not lntended to limit the in~ention except
as de~ined in the followlng cla Ds.
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