PLANETARY GEAR TRANSMISSION

TRANSMISSION A ENGRENAGES PLANETAIRES

English Abstract

PLANETARY GEAR TRANSMISSION
Abstract of the Disclosure
A planetary transmission for selectively shifting among six
forward speeds and two reverse speeds includes a single planet
carrier carrying four planet gear sets and clutchable to a
drive shaft. First and second planet gear sets mesh respectively
with first and second sun gears secured to the drive shaft and
with encircling brake-associated first and second ring gears. A
third planet gear set meshes with a centrally apertured third sun
gear and with an encircling brake-associated third ring gear. A
fourth planet gear set meshes with the third planet gear set and
with a fourth sun gear secured to a driven shaft which extends
through the central aperture of the third sun gear and which is
clutchable to the third sun gear.

Claims

The embodiments of the invention in which an exclusive
property or privilege is claimed are defined as follows:
1. A transmission comprising: a drive shaft; a driven
shaft; first, second, and third axially spaced planetary units
having a rotatable common planet carrier spanning the shafts;
said first planetary unit including a first sun gear secured to
the drive shaft, a first rotatable ring gear surrounding the
first sun gear, and a first planet gear journaled in the planet
carrier meshing with the first sun gear and the first ring gear;
first brake means for selectively braking and releasing the first
ring gear; first clutch means for selectively coupling the planet
carrier and the drive shaft together; said second planetary unit
including a second sun gear secured to the drive shaft axially
spaced from the first sun gear, a second rotatable ring gear
surrounding the second sun gear, and a second planet gear jour-
naled in the planet carrier for rotation independent of the first
planet gear meshing with the second sun gear and the second ring
gear; second brake means for selectively braking and releasing
the second ring gear; said third planetary unit including a third
and fourth relatively rotatable sun gears, a third ring gear
surrounding said third sun gear, a third planet gear journaled in
the planet carrier meshing with the third sun gear and the third
ring gear, and a fourth planet gear journaled in the planet
carrier meshing with the third planet gear and the fourth sun
gear; third brake means for selectively braking and releasing the
third ring gear; fourth brake means for selectively braking and
releasing the third sun gear; second clutch means for selectively
coupling the third and fourth sun gears together whereby the
driven shaft is rotatable at six different forward ratios when
the first, second, and fourth brakes are selectively braked and
released and the first and second clutches are selectively coupled
and released and whereby the driven shaft is rotatable at two

different reverse ratios when the first and second brakes are
alternately braked and released with the third brake braked.
2. The transmission as claimed in claim 1 wherein the
second planetary unit is coaxially behind the first planetary
unit and the fourth sun gear is located ahead of the third sun
gear and rearwardly of the first and second sun gears, the third
sun gear is axially hollow and the driven shaft extends coaxially
therethrough and is connected to the fourth sun gear, and the
fourth brake means includes a hollow portion coaxially surround-
ing the driven shaft and coaxially connected to the third sun
gear.
3. The transmission as claimed in claim 1 wherein the
drive shaft, the planet carrier, and the driven shaft are coaxial
on a fore and aft axis, the second sun gear is spaced rearwardly
of the first sun gear, the first clutch means is secured to the
drive shaft ahead of the first sun gear, and the second clutch
means is secured to the driven shaft behind the third sun gear.
4. The transmission as claimed in claim 3 wherein the
third sun gear is axially hollow and is spaced rearwardly from
the fourth sun gear, the fourth brake means includes a hollow
intermediate portion coaxially connected to and extending rear-
wardly from said third sun gear, and said fourth sun gear is
coaxially between the second and third sun gears and is secured
to the driven shaft which extends rearwardly through said hollow
intermediate portion.
5. A transmission comprising: a drive shaft; a driven
shaft; first, second, and third axially spaced planetary units
having a rotatable common planet carrier spanning the shafts;
said first planetary unit including a first driven gear secured
to the drive shaft, a first rotatable reaction gear surrounding
the first driven gear, and a first planet gear journaled on the
planet carrier meshing with the first driven gear and the first

reaction gear; first brake means for selectively braking and
releasing the first reaction gear; first clutch means for selec-
tively coupling the planet carrier and the drive shaft together;
said second planetary unit including a second driven gear secured
to the drive shaft axially spaced from the first driven gear, a
second rotatable reaction gear surrounding the second driven
gear, and a second planet gear journaled in the planet carrier
for rotation independent of the first planet gear meshing with
the second driven gear and the second reaction gear; second brake
means for selectively braking and releasing the second reaction
gear; said third planetary unit including a third and fourth
relatively rotatable driven gears, a third reaction gear surround-
ing said third driven gear, a third planet gear journaled in the
planet carrier meshing with the third driven gear and the third
reaction gear, and a fourth planet gear journaled in the planet
carrier meshing with the third planet gear and the fourth driven
gear; third brake means for selectively braking and releasing the
third reaction gear; fourth brake means for selectively braking
and releasing the third driven gear; second clutch means for
selectively coupling the third and fourth driven gears together
whereby the driven shaft is rotatable at six different forward
ratios when the first, second, and fourth brakes are selectively
braked and released and the first and second clutches are selec-
tively coupled and released and whereby the driven shaft is
rotatable at two different reverse ratios when the first and
second brakes are alternately braked and released with the
third brake braked.
6. A transmission comprising: a drive shaft; a driven
shaft; first, second, and third axially spaced planetary units
having a rotatable common planet carrier spanning the shafts;
said first planetary unit including a first sun gear secured to
the drive shaft, a first rotatable ring gear surrounding the

first sun gear, and a first planet gear journaled in the planet
carrier meshing with the first sun gear and the first ring gear;
first brake means for selectively braking and releasing the first
ring gear; first clutch means secured to the drive shaft for
selectively clutching the planet carrier directly to the drive
shaft; said second planetary unit including a second sun gear
secured to the drive shaft axially spaced from the first sun gear
for common rotation with the first sun gear, a second rotatable
ring gear surrounding the second sun gear, and a second planet
gear journaled in the planet carrier independent of and offset
from the first planet gear meshing with the second sun gear and
the second ring gear; second brake means for selectively braking
and releasing the second ring gear; said third planetary unit
including a third and fourth relatively rotatable sun gears, a
third ring gear surrounding said third sun gear, a third planet
gear journaled in the planet carrier meshing with the third sun
gear and the third ring gear, and a fourth planet gear journaled
in the planet carrier meshing with the third planet gear and the
fourth sun gear; third brake means for selectively braking and
releasing the third ring gear; fourth brake means for selectively
braking and releasing the third sun gear; second clutch means for
selectively coupling the third and fourth sun gears together
whereby the driven shaft is rotatable at six different forward
ratios when the first, second, and fourth brakes are selectively
braked and released and the first and second clutches are selec-
tively coupled and released and whereby the driven shaft is
rotatable at two different reverse ratios when the first and
second brakes are alternately braked and released with the third
brake braked.
7. The transmission as claimed in claim 6 wherein the
second planetary unit is coaxially behind the first planetary
unit and the fourth sun gear is located ahead of the third sun
11

gear and rearwardly of the first and second sun gears, the third
sun gear is axially hollow and the driven shaft extends coaxially
therethrough and is connected to the fourth sun year, and the
fourth brake means includes a hollow portion coaxially surround-
ing the driven shaft and coaxially connected to the third sun
gear.
8. The transmission as claimed in claim 6 wherein the
drive shaft, the planet carrier, and the driven shaft are coaxial
on a fore and aft axis, the second sun gear is spaced rearwardly
of the first sun gear, the first clutch means is secured to the
drive shaft ahead of the first sun gear, and the second clutch
means is secured to the driven shaft behind the third sun gear.
9. The transmission as claimed in claim 8 wherein the
third sun gear is axially hollow and is spaced rearwardly from
the fourth sun gear, the fourth brake means includes a hollow
intermediate portion coaxially connected to and extending rear-
wardly from said third sun gear, and said fourth sun gear is
coaxially between the second and third sun gears and is secured
to the driven shaft which extends rearwardly through said hollow
intermediate portion.
10. A transmission comprising: a drive shaft; a driven
shaft; first, second, and third axially spaced planetary units
having a rotatable common planet carrier spanning the shafts;
said first planetary unit including a first driven gear secured
to the drive shaft, a first rotatable reaction gear surrounding
the first driven gear, and a first planet gear journaled on the
planet carrier meshing with the first driven gear and the first
reaction gear; first brake means for selectively braking and
releasing the first reaction gear; first clutch means secured to
the drive shaft for selectively clutching the planet carrier
directly to the drive shaft; said second planetary unit including
a second driven gear secured to the drive shaft axially spaced
12

Claim 10 continued
from the first driven gear for common rotation with the first
driven gear, a second rotatable reaction gear surrounding the
second driven gear, and a second planet gear journaled in the
planet carrier independent of and offset from the first planet
gear meshing with the second driven gear and the second reaction
gear; second brake means for selectively braking and releasing
the second reaction gear; said third planetary unit including a
third and fourth relatively rotatable driven gears, a third
reaction gear surrounding said third driven gear, a third planet
gear journaled in the planet carrier meshing with the third
driven gear and the third reaction gear, and a fourth planet gear
journaled in the planet carrier meshing with the third planet
gear and the fourth driven gear; third brake means for selec-
tively braking and releasing the third reaction gear; fourth
brake means for selectively braking and releasing the third
driven gear; second clutch means for selectively coupling the
third and fourth driven gears together whereby the driven shaft
is rotatable at six different forward ratios when the first,
second, and fourth brakes are selectively braked and released and
the first and second clutches are selectively coupled and
released and whereby the driven shaft is rotatable at two differ-
ent reverse ratios when the first and second brakes are alter-
nately braked and released with the third brake braked.
13

Description

1069~735
l PLANETARY GEAR TRANSMISSION
The present invention relates generally to vehicle power
shift transmissions and more particularly to a planetary trans-
mission which is capable of being shifted between six forward
` speeds and two reverse speeds.
In the past, a relatively complex system of gears, brakes,
and clutches were required in order to provide a large number of
speed ratios as shown in the U. S. Patent 3,298,252 granted to
K. J. Harris et al which provided eight forward and four reverse
10 speeds. With further development of planetary transmissions,
simple arrangements have been devised such as that shown in the
U. S. Patent 3,381,546 granted to H. H. Holl; however, with
simplification, the number of speed ratios has been decreased,
for example with the Holl transmission only four forward and
three reverse speeds are available.
~: Summary of the Invention
The present invention provides a six forward and two reverse
speed planetary transmission requiring a minimum number of gears,
- brakes, and clutches. A drive shaft is provided which is clutch-
i 20 able for driving a common planet carrier in the transmission.
Two sun gears are mounted on the drive shaft and mesh with two
planet gear sets mounted in the carrier. The two planet gear
sets each mesh with a brake-associated ring gear to selectively
drive the carrier. Two other meshing planet gear sets in the
- carrier mesh respectively with brake-associated and output-shaft-
associated sun gears which are clutchable together to be
driven by the carrier and which are unclutchable to allow the
driven-shaft-associated sun gear to be driven by the meshing
planet gear sets.
Brief Description of the Drawings
Fig. l is a diagrammatic longitudinal view, partially in
section, of the planetary transmission of the present invention;
- 1 -
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06973S
Fig. 2 is a cross-sectional view taken along the line 2--2
of Fig. l; and
Fig. 3 is a cross-sectional view taken along the line 3--3
of Fig. 1.
Description of the Preferred Embodiment
Referring now to Fig. 1, therein is shown a planetary trans-
mission generally designated by the numeral 10. The transmission
10 is driven by a drive shaft 12 which is generally connected
to an internal combustion engine (not shown~. The drive shaft
12 is splined to an input hub 14 which includes a first clutch 16
having conventional clutch components. The first clutch 16 is
clutchable to couple the input hub 14 to a comn planet carrier
generally designated by the numeral 18 which is positioned rear-
wardly of the input hub 14. The expression "rearwardly " is used
on the basis of a typical fore and aft disposition of the trans-
mission in a vehicle; however, it will be realized that such an
~- expression is used for purposes of convenience and not by way of
limitation.
.
The planet carrier 18 is relatively long in fore and aft
`~ 20 extension and has front and rear walls 20 and 22, respectively,
coaxially apertured at 24 and 26, respectively. The planet
carrier 18 has means rigidly interconnecting the front and rear
walls 20 and 22, and this means includes several shafts, for
carrying planet gears to be hereinafter described, together with
circumferentially spaced wall portions.
~,r,~ The drive shaft 12 extends through the aperture 24 in the
front wall 20 of the planet carrier 18 and has secured thereto
a first sun gear 28 and rearwardly therefrom a second sun gear
30.
The first sun gear 28 meshes with a first planet gear set 32
which consists of three gears as shown in Fig. 2 and which are
bearing-mounted on a set of three equalaterally spaced first
- 2 -
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~069735
1 shafts 34. m e first shafts 34 are rigidly secured to the
planet carrier 18 so as to allow the first planet gear set 32 to
protrude from the planet carrier 18 and mesh with a first ring
gear 36. The first ring gear 36 concentrically encircles the
first sun gear 28 and is floatingly carried by the first planet
gear set 32. m e first ring gear 36 is associated with a first
- brake 38 having conventional components which allow the first
ring gear 36 to be selectively braked and released relative to
a transmission housing 40.
The second sun gear 30 meshes with a second planet gear set
42 which is similar to the first planet gear set 32 in consist-
: ing of three gears which are bearing-mounted on a set of three
equilaterally spaced second shafts 44. Only one second planet
" gear 42 and one second shaft 44 is shown in the drawings. The
1 second shafts 44 are rigidly secured to the planet carrier 18
', and positioned so as to allow the second planet gear set 42 to :
~ . protrude therefrom to engage a second ring gear 46. The second
:
ring gear 46 concentrically encircles the second sun gear 30 and
; is floatingly carried by the second planet gear set 42. The
. 20 second ring gear 46 is associated with a second brake 48 having
conventional components for selectively braking and releasing
the second ring gear 46 relative to the transmission housing 40.
The second shaft set 44 extends rearwardly from the second
planet gear set 42 into the rear wall 22 of the planet carrier 18.
On the second shaft set 44, just forwardly of the rear wall 22
. are bearing-mounted the gears of a third planet gear set 50 which
consists of three equilaterally sp~ced gears as shown in Fig. 3.
The third planet gear set 50 protrudes from the planet car-
rier 18 to mesh with a third ring gear 52. The third ring gear
52 concentrically encircles a third sun gear 56 and is float-
îngly carried by the third planet gear set 50. The third ring
gear 52 is associated with a third brake 54 having conventional
components for selectively braking and releasing the third ring
-- 3

`1`(:~6~735
1 gear 52 relative to the transmission housing 40. The third
planet gear set 50 further meshes with the centrally apertured
third sun gear 56. The third sun gear 56 is connected by a
hollow intermediate portion 58 to a third sun gear hub 60 which
is associated with a fourth brake 62 having conventional compo-
nents for selectively braking and releasing the third sun gear
56 relative to the transmission housing 40.
The third planet gear set 50 still further meshes with a
; fourth planet gear set 64 consisting of three gears which are
, 10 bearing-mounted on a set of three equilaterally spaced third
` shafts 66 so as to not protrude from the planet carrier 18. The
fourth planet gear set 64 meshes with a fourth sun gear 68 for-
~~ ward of the third sun gear 56. The fourth sun gear 68 is secured
to a driven shaft 70 which extends rearwardly from the planet
:
carrier 18 through the centrally apertured third sun gear 56 and
the hollow intermediate portion 58 to the exterior of the trans-
; mission housing 40. Just rearwardly of the third sun gear hub
~' 60 is secured a second clutch 72 having conventional components
for selectively coupling and uncoupling the third sun gear hub
- 20 60 and the driven shaft 70; i.e. coupling and uncoupling the
third and fourth sun gears 56 and 58.
"!` From the description thus far, and noting that drive shaft
12 may be connected to a power source such as an internal com-
bustion engine by a clutch or other torque transmitting mechanism,
:- it will be seen that the drive shaft 12 may be regarded as a
constantly rotating part.
A first forward speed is obtained by braking the first
brake 38 and the second clutch 72. The rotation of the drive
shaft 12 is transmitted through the first sun gear 28 to the
- 30 first planet gear set 32 which is forced to translate because
` the first ring gear 36 is braked by the first brake 38. The
- translation of the first planet gear set 32 causes rotation of the
.:
planet carrier 18. The rotation of the planet carrier 18 is
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10~73S
transmitted through the third and fourth planet gears 50 and 64
to the third and fourth sun gears 56 and 64 which are prevented
from rotating relative to one another due to the engagement of
the second clutch 72 which causes the driven shaft 70 to rotate
at the same speed as the planet carrier 18.
A second forward speed is obtained by braking the second
brake 48 while the second clutch 72 remains engaged. The rota-
tion of the drive shaft 12 is then transmitted through the second
sun gear 30 to the second planet gear set 42 which is forced to
- 10 translate since the second ring gear 46 is braked by the second
brake 48. The translation of the second planet gear 42 causes
. .
rotation of the planet carrier 18 at a speed different from that
. in the first forward speed. Since the second clutch 72 is en-
gaged the driven shaft 70 will again rotate at the same speed as
. the planet carrier 18.
A third forward speed is obtained by braking the first brake
38 and the fourth brake 62. The rotation of the drive shaft 12
is transmitted through the first sun gear 28 to the first planet
gear set 32 which is forced to translate because of the first
20 ring gear 36 is held by the first brake 38. The translation of
the first planet gear set 32 causes rotation of the planet car-
rier 18 and thus translation of the third planet gear set 50.
With the fourth brake 62 braking the third sun gear hub 60 and
therefore the third sun gear 56, the translation of the third
planet gear set 50 around the third sun gear 56 causes rotatio~n
~:~ of the third planet gear set 50. The rotation of the third planet
gear set 50 is transmitted throug~ the fourth planet gear set 64
to the fourth sun gear 68 and thence to the driven shaft 70.
A fourth forward speed is obtained by braking the second
30 brake 48 and the fourth brake 62. The rotation of the drive
shaft 12 is then transmitted through the second sun gear 30 to
the second planet gear set 42 which translates because the second
ring gear 46 is braked by the second brake 48. The translation
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-` 106g73S
1 of the second planet gear set 42 causes rotation of the planet
carrier 18 which causes translation of the third planet gear
; set 50. The third planet gear set 50 rotates because the third
` sun gear 56 is braked by the fourth brake 62 and the rotation of
the third planet gear set 50 is transmitted through the fourth
. planet gear set 64 to the fourth sun gear 68 and thence to the
driven shaft 70.
i A fifth forward speed is obtained by clutching the first and
.: second clutches 16 and 72. The rotation of the drive shaft 12
is transmitted through the first clutch 16 to the planet carrier
18 and thence through the second clutch 72 into the driven shaft
70 so as to provide a direct mechanical drive from the drive
;~ shaft 12 to the driven shaft 70.
A sixth forward speed may be obtained by clutching the first
clutch 16 and braking the fourth brake 62. The rotation of the
.~: drive shaft 12 is transmitted through the first clutch 16 to the
,, planet carrier 18 to cause translation of the third planet gear
;,~,.:
set 50 and rotation thereof since the third sun gear 56 is braked
. by the fourth brake 62. The rotation of the third planet gear
set 50 is transmitted through the fourth planet gear set 64 to
,,:
:.~ the fourth sun gear 68 and thence to the driven shaft 70.
. A first reverse speed is obtained by braking the first and
third brakes 38 and 54. The rotation of the drive shaft 12 is
transmitted through the first sun gear 28 to the first planet gear
set 32 which is forced to translate and cause rotation of the
planet carrier 18 since the first ring gear 36 is braked by the
first brake 38. The rotation of the planet carrier 18 causes
: transslation of the third planet gear set 50 which rotates in an
.
.:. opposite direction from that of the forward speeds since the
- 30 third ring gear 52 is braked by the third brake 54. The reverse
:
. rotation of the third planet gear set 50 is transmitted through
the fourth planet gear set 64 to the fourth sun gear 68 and
: thence to the driven shaft 70 to cause rotation thereof at a
: first reverse speed.
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1069~3S
1 A second reverse speed is obtained by braking the second and
third brakes 48 and 54. The rotation of the drive shaft 12 is
transmitted through the second sun gear 30 to the second planet
gear set 42 which is forced to translate and rotate the planet
carrier 18 due to the braking of the second ring gear 46 by the
second brake 48. The translation of the planet carrier 18
causes translation of the third planet gear set 50 and reverse
rotation thereof due to the third ring gear 52 being braked by
; the third brake 54. The reverse rotation of the third planet gear
set 50 is transmitted through the fourth planet gear set 64 to the
fourth sun gear 68 and thence to the driven shaft 70 to cause
rotation thereof at a second reverse speed.
While the invention has been described in conjunction with a
specific embodiment, it is to be understood that many alterna-
tives, modifications, and variations will be apparent to those
skilled in the art in light of the aforgoing description. Ac-
cordingly, it is intended to embrace all such alternatives,
modifications, and variations which fall within the spirit and
scope of the appended claims.
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