Planetary gearing arrangement for a transmission

A planetary gearing arrangement having a plurality of interconnected planetary gear sets controlled by friction drive establishing devices such as clutches and brakes for selectively establishing a plurality of forward drive ratios and a reverse drive ratio. The number of forward drive ratios available is one greater than the number of friction drive establishing devices. Each ratio change between the forward drives is accomplished by a single transition interchange of the friction drive establishing devices.

This invention relates to planetary gear arrangements and more particularly 
to multi-speed planetary gear arrangements having single transition 
shifting between drive ratios. 
It is an object of this invention to provide an improved multi-speed 
planetary gearing arrangement wherein a plurality of simple planetary gear 
sets and friction drive establishing devices are combined to provide a 
plurality of forward speed ratios being one greater in number than the 
number of friction devices and wherein the interchange of successive 
forward ratios is accomplished by single transition shifting. 
Another object of this invention is to provide an improved planetary 
gearing arrangement for use in a transmission wherein the gear arrangement 
has at least three planetary gear sets which are operatively 
interconnected between the input and output members and are also 
interconnected with five friction devices including two clutches, two 
brakes and one other friction drive establishing device, all of which are 
selectively operable to provide six forward speed ratios with single 
transition shifting therebetween. 
A further object of this invention is to provide an improved planetary 
gearing arrangement having an input shaft and an output shaft and a 
plurality of simple planetary gear sets disposed therebetween, and wherein 
each gear set has an input member, an output member and a reaction member 
with a first of the gear set having its output connected to the output 
shaft and its input selectively connected to the input shaft by a clutch, 
a second of the gear sets having its output connected to the first gear 
set and its input selectively connectable through a clutch to the input 
shaft, and a third of the gear sets having its output connected to the 
second gear set, and wherein a brake is provided for each reaction member 
of the first and second gear set and wherein the clutches, brakes and 
friction device may be controlled to establish a plurality of forward 
drive ratios one greater in number than the clutches, brakes and friction 
device and wherein interchange between successive ratio is accomplished by 
simple transition shifting.

Referring to the drawings wherein like characters represent the same or 
corresponding parts there is seen in FIG. 1 a planetary gearing 
arrangement having an input shaft 10, an output shaft 12 and three 
planetary gear sets 14, 16 and 18 disposed therebetween. The input shaft 
10 is drivingly connected to a clutch drum 20 which drum 20 provides input 
drives for clutches 22 and 24. The clutch drum 20 is also drivingly 
connected to a gear 26 which is a component of the planetary gear set 18. 
The input shaft 10 is preferably driven by a conventional torque 
converter, not shown, which torque converter is driven by an engine in a 
well known manner. 
The input clutch 22 is connected to a shaft 28 which in turn is connected 
to sun gears 30 and 32 which are components of planetary gear arrangements 
14 and 16 respectively. The input clutch 24 is connected to a shaft 34 
which is connected to a planet carrier 36 which is a component of the 
planetary gear set 16 and which carrier 36 is connected through a hub 38 
to a ring gear 40 which is a component of planetary gear set 14. 
The planetary gear set 14 also includes a planet carrier 42 on which is 
rotatably mounted a plurality of pinion gears 44, only one of which is 
shown, meshing with the sun gear 30 and the ring gear 40. The ring gear 40 
is operatively connected with a friction brake 46 which may be selectively 
engaged to restrain rotation of the ring gear 40 and the carrier 36. The 
carrier 42 is drivingly connected to the output shaft 12. 
The planetary gear set 16 also includes a ring gear 48 and a plurality of 
pinion gears 50, which pinion gears 50 are rotatably mounted on carrier 36 
and mesh with sun gear 32 and ring gear 48. The ring gear 48 is 
operatively connected to a friction brake 52 which may be selectively 
engaged to restrain rotation of the ring gear 48. 
The planetary gear set 18 includes a ring gear 54, a planet carrier 56 and 
a plurality of pinion gears 58 which are rotatably mounted on carrier 56 
and mesh with sun gear 26 and ring gear 54. The carrier 56 is drivingly 
connected to a hub 60 which is connected to the ring gear 48. The ring 
gear 54 is operatively connected to a friction brake 62 which may be 
selectively engaged through restrain rotation of ring gear 54. 
The clutches 22 and 24 and the brakes 46, 52 and 62 are preferably of the 
multiple disc type fluid actuated friction drive establishing device which 
are commonly used in planetary gear transmissions. The construction, 
operation, and control of these devices is well known to those familiar 
with the art of power transmission such that a detailed description of 
these units is not considered necessary. 
The gearing arrangements shown in FIG. 1 can be controlled by the clutches 
and brakes to provide six forward drive ratios and one reverse drive 
ratio. The terms forward and reverse of course refer to vehicle operation 
and indicate that the output shaft 12 will rotate in the same direction as 
input shaft 10 for the six forward drive ratios and in the opposite 
direction for the reverse drive ratio. The first and lowest speed ratio is 
established by the engagement of clutch 22 and brake 46. This establishes 
ring gear 40 as a reaction member in planetary set 14 and sun gear 30 as 
the input member of planetary set 14. The output of the planetary set 14 
during this drive ratio is carrier 42 which is driven in the same 
direction as input shaft 10 but at a reduced speed. 
The second forward drive ratio is established by the disengagement of brake 
46 and the substantially simultaneous engagement of brake 52. This 
releases ring gear 40 of planetary gear set 14 while restraining rotation 
of ring gear 48 of planetary set 16. This establishes ring gear 48 as a 
reaction member. Since sun gear 32 is driven forwardly by the input shaft 
10 through clutch 22, the carrier 38 and therefore ring gear 40 will be 
driven forwardly at a reduced speed. Thus ring gear 40 becomes an input 
member for planetary set 14. Since sun gear 30, ring gear 40 are driven 
forwardly, the carrier 42 will be driven forwardly at a more rapid speed 
than was available for a given input speed in the first gear ratio. 
The third forward drive ratio is established by disengagement of brake 52 
and substantially simultaneous engagement of brake 62. This action 
releases ring gear 48 while restraining rotation of ring gear 54. Since 
the sun gear 26 is driven in the forward direction and ring gear 54 is a 
reaction member, the carrier 56 and therefore ring gear 48 will be driven 
forwardly at a reduced ratio. Thus both sun gear 32 and ring gear 48 are 
input members such that the carrier 36 will be driven forwardly at a more 
rapid speed than was available in the second speed ratio. This increase in 
the speed of carrier 36 is also operative on ring gear 40 such that 
carrier 42 and therefore output shaft 12 are rotated at a higher speed 
than was available, for a given input speed, in the second gear ratio. 
To establish the fourth forward speed ratio the brake 62 is disengaged 
while the clutch 24 is substantially simultaneously engaged. With both 
clutches 22 and 24 engaged the planetary gear sets 14 and 16 will be 
locked up and therefore the carrier 42 will rotate at a speed equal to the 
speed of input shaft 10. 
To establish the fifth forward drive ratio, the clutch 22 is disengaged 
while the brake 62 is substantially simultaneously engaged. This 
establishes ring gear 54 as a reaction member and frees sun gears 30 and 
32 from the input shaft 10. The carrier 56 of planetary set 18 is driven 
forwardly at a reduced speed which of course causes ring gear 48 of the 
planetary ring gear 16 to rotate forwardly at a reduced speed. The carrier 
36 of planetary gear set 16 is driven forwardly at the same speed as the 
input shaft 10 as is the ring gear 40 of planetary gear set 14. The sun 
gears 32 and 30 are overdriven in a forward direction resulting in an 
overdrive ratio being attained at carrier 42 and therefore output shaft 
12. 
The sixth forward drive ratio is established by disengagement of brake 62 
and substantially simultaneously engagement of brake 52. This establishes 
ring gear 48 as a reaction member in planetary gear set 16 such that sun 
gears 32 and 30 are overdriven at a more rapid speed than was attained in 
the fifth speed ratio for a given input speed. This of course results in a 
higher overdrive at carrier 42 and therefore output shaft 12. 
To establish the reverse drive ratio, brake 62 and brake 46 are engaged 
while the remaining clutches and brakes are disengaged. Since brake 62 is 
engaged the ring gear 54 is a reaction member such that when sun gear 26 
is driven forwardly by the input shaft 10, the carrier 56 and therefore 
ring gear 48 will be driven forwardly at a reduced ratio. Since brake 46 
is engaged the carrier 36 and ring gear 40 are both reaction members such 
that sun gear 32 will be driven in a direction opposite to the input shaft 
10 as is the sun gear 30. Since the sun gear 30 is driven oppositely to 
the input shaft 10 and since ring gear 40 is a reaction member, the 
carrier 42 will be driven in a direction opposite to the input shaft 10 as 
will the output shaft 12. 
It is apparent from the foregoing description of the forward drive ratios 
that each ratio requires the engagement of different combinations of two 
of the five friction drive establishing devices. It is also apparent from 
the foregoing description that the interchange between successive forward 
ratios is accomplished by the disengagement of one of the drive 
establishing devices and the substantially simultaneous engagement of 
another drive establishing device. This is termed a single transition 
shift. There is no occurrence upon shifting between successive drive 
ratios where both of the controlling friction drive establishing devices 
are disengaged so that the establishment of two new controlling devices 
can be attained. This later condition is normally termed a double 
transition shift and usually results in the changing of gear ratios in two 
or more gear sets simultaneously. 
Double transition shifting is difficult from a control standpoint, since 
the proper overlap of this type of friction device interchange is very 
difficult to attain. This is generally an undesirable feature in a power 
shifting type transmission. It can also be noted from the above 
description that the use of only five friction drive establishing devices 
permits the establishment of six forward speed ratios. Thus the number of 
speed ratios in the forward direction is one greater than the number of 
friction drive establishing devices contained in the transmission. 
FIG. 2 is substantially the same as FIG. 1 with the addition of a planetary 
gear set designated 64. This planetary gear set includes a sun gear 66 
which is connected to the shaft 28, a ring gear 68 which is operatively 
connected with a selectively operable friction brake 70, a carrier 72 
which is connected to the carrier 42 and output shaft 12, and a plurality 
of pinion gears 74 which are rotatably mounted on the carrier 72 and mesh 
with the sun gear 66 and ring gear 68. The planetary gear sets 14, 16 and 
18 and clutches 22 and 24 and brakes 46, 52 and 62 cooperate to provide 
six forward speeds as described for FIG. 1. The planetary gear set 64 is 
operable to provide a seventh forward speed. To establish a forward speed 
ratio in planetary gear set 64 the brake 70 is engaged and clutch 22 is 
engaged. This establishes a reduction drive ratio through planetary gear 
set 64 from the input shaft 10 to the output shaft 12. The gear ratio 
obtainable by planetary gear set 64 is most adapted to be useful as a gear 
ratio between the first and second ratios defined above for FIG. 1. Thus 
in the planetary gearing arrangement shown in FIG. 2, the first four 
forward speed ratios would be established by the following engagement and 
disengagement schedule of the clutches and brakes. First drive ratio is 
established by clutch 22 and brake 46, the second forward drive ratio is 
established by the interchange of the brakes 46 and 70, the third forward 
drive ratio is established between interchange of brakes 70 and 52, and 
the fourth forward drive ratio is established between interchange of 
brakes 52 and 62. The fifth, sixth and seventh gear ratios are established 
the same as those described above for FIG. 1. It is readily apparent that 
the advantages of the FIG. 1 transmission are found in the transmission 
shown in FIG. 2. 
The transmission shown in FIG. 3 is also substantially identical with the 
transmission shown in FIG. 1 except that brake 62 has been replaced by a 
clutch 76 which is positioned between the input clutch hub 20 and sun gear 
26. It should also be noted that ring gear 54 is permanently grounded to 
the transmission housing. The drive ratios associated with FIG. 3 are 
obtained in substantially the same manner as those described above for 
FIG. 1 with the exception that clutch 76 is engaged to establish the third 
and fifth forward drive ratios and the reverse drive ratio. The 
transmission arrangement shown in FIG. 1 is preferable to that shown in 
FIG. 3 since the average slip speeds between the friction plates of brake 
62, when disengaged, are less than the slip speeds between the clutch 76 
when disengaged, for the various speed ratios. From the foregoing 
description of FIGS. 1, 2 and 3 it should be obvious to those skilled in 
the art that the additional planetary gear set shown in FIG. 2 can also be 
combined with the planetary gearing arrangement shown in FIG. 3 to provide 
seven forward speeds. 
Obviously, many modifications and variations are possible in light of the 
above teaching. It is, therefore, to be understood that within the scope 
of the appended claims the invention may be practiced otherwise than is 
specifically described.