Title of Invention	A POWER TRANSMISSION WITH FOUR PLANETARY GEAR SETS THAT ARE CONTROLED BY SIX TORQUE-TRANSMITTING DEVICES TO PROVIDE NINE FORWARD SPEED RATIOS AND ONE REVERSE SPEED RATIO
Abstract	The transmission has a plurality of members that can be utilized in powertrains to provide nine forward speed ratios and one reverse speed ratio. The transmission includes four planetary gear sets, six torque-transmitting devices, and three fixed interconnections. The powertrain includes an engine and torque converter that is continuously connected to one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The six torque-transmitting devices provide interconnections between various gear members, and the transmission housing, and are operated in combinations of three to establish nine forward speed ratios and one reverse speed ratio.

Title of Invention

A POWER TRANSMISSION WITH FOUR PLANETARY GEAR SETS THAT ARE CONTROLED BY SIX TORQUE-TRANSMITTING DEVICES TO PROVIDE NINE FORWARD SPEED RATIOS AND ONE REVERSE SPEED RATIO

Abstract

The transmission has a plurality of members that can be utilized in powertrains to provide nine forward speed ratios and one reverse speed ratio. The transmission includes four planetary gear sets, six torque-transmitting devices, and three fixed interconnections. The powertrain includes an engine and torque converter that is continuously connected to one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The six torque-transmitting devices provide interconnections between various gear members, and the transmission housing, and are operated in combinations of three to establish nine forward speed ratios and one reverse speed ratio.

Full Text	9-SPEED TRANSMISSION TECHNICAL FIELD [0001] The present invention relates to a power transmission having four planetary gear sets that are controlled by six torque-transmitting devices to provide nine forward speed ratios and one reverse speed ratio. BACKGROUND OF THE INVENTION [0002] Passenger vehicles include a powertrain that is comprised of an engine, multi- speed transmission, and a differential or final drive. The multi-speed transmission increases the overall operating range of the vehicle by permitting the engine to operate through its torque range a number of times. The number of forward speed ratios that are available in the transmission determines the number of times the engine torque range is repeated. Early automatic transmissions had two speed ranges. This severely limited the overall speed range of the vehicle and therefore required a relatively large engine that could produce a wide speed and torque range. This resulted in the engine operating at a specific fuel consumption point during cruising, other than the most efficient point. Therefore, manually-shifted (countershaft transmissions) were the most popular. [0003] With the advent of three- and four-speed automatic transmissions, the automatic shifting (planetary gear) transmission increased in popularity with the motoring public. These transmissions improved the operating performance and fuel economy of the vehicle. The increased number of speed ratios reduces the step size between ratios and therefore improves the shift quality of the transmission by making the ratio interchanges substantially imperceptible to the operator under normal vehicle acceleration. [0004] Six-speed transmissions offer several advantages over four- and five-speed transmissions, including improved vehicle acceleration and improved fuel economy. While many trucks employ power transmissions having six or more forward speed ratios, passenger cars are still manufactured with three- and four-speed automatic transmissions and relatively few five- or six-speed devices due to the size and complexity of these transmissions. [0005] Seven-, eight- and nine-speed transmissions provide further improvements in acceleration and fuel economy over six-speed transmissions. However, like the six-speed transmissions discussed above, the development of seven-, eight- and nine-speed transmissions has been precluded because of complexity, size and cost. SUMMARY OF THE INVENTION [0006] It is an object of the present invention to provide an improved transmission having four planetary gear sets controlled to provide nine forward speed ratios and one reverse speed ratio. [0007] The transmission family of the present invention has four planetary gear sets, each of which includes a first, second and third member, which members may comprise a sun gear, a ring gear, or a planet carrier assembly member, in any order. [0008] In referring to the first, second, third and fourth gear sets in this description and in the claims, these sets may be counted "first" to "fourth" in any order in the drawing (i.e., left to right, right to left, etc.). Additionally, the first, second or third members of each gear set may be counted "first" to "third" in any order in the drawing (i.e., top to bottom, bottom to top, etc.) for each gear set. [0009] Each carrier member can be either a single-pinion carrier member (simple) or a double-pinion carrier member (compound). Embodiments with long pinions are also possible. [0010] A first interconnecting member continuously connects the third member of the first planetary gear set with the second member of the second planetary gear set. [0011] A second interconnecting member continuously connects the third member of the second planetary gear set with the second member of the third planetary gear set and with the third member of the fourth planetary gear set. [0012] A third interconnecting member continuously connects the first member of the first planetary gear set with the first member of the third planetary gear set. [0013] The input member is continuously connected with the first member of the fourth planetary gear set. The output member is continuously interconnected with the third member of the third planetary gear set. [0014] A first torque-transmitting device, such as a brake, selectively connects the first member of the first planetary gear set with a stationary member (transmission housing/casing). [0015] A second torque-transmitting device, such as a brake, selectively connects the second member of the fourth planetary gear set with a stationary member (transmission housing/casing). [0016] A third torque-transmitting device, such as a clutch, selectively connects the first member of the first planetary gear set with the first member of the second planetary gear set. [0017] A fourth torque-transmitting device, such as a clutch, selectively connects the second member of the first planetary gear set with the first member of the fourth planetary gear set. [0018] A fifth torque-transmitting device, such as a clutch, selectively connects the second member of the first planetary gear set with the second member of the fourth planetary gear set. [0019] A sixth torque-transmitting device, such as a clutch, selectively connects the third member of the second planetary gear set with the first member of the second planetary gear set. [0020] The six torque-transmitting devices are selectively engageable in combinations of three to yield nine forward speed ratios and one reverse speed ratio. [0021] A variety of speed ratios and ratio spreads can be realized by suitably selecting the tooth ratios of the planetary gear sets. [0022] The above features and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS [0023] FIGURE la is a schematic representation of a powertrain including a planetary transmission in accordance with the present invention; [0024] FIGURE 1b is a truth table and chart depicting some of the operating characteristics of the powertrain shown in Figure la; and [0025] FIGURE 1c is a schematic representation of the powertrain of Figure la depicted in lever diagram form. DESCRIPTION OF THE PREFERRED EMBODIMENT [0026] Referring to the drawings, there is shown in Figure la a powertrain 10 having a conventional engine and torque converter 12, a planetary transmission 14, and a conventional final drive mechanism 16. The engine 12 may be powered using various types of fuel to improve the efficiency and fuel economy of a particular application. Such fuels may include, for example, gasoline; diesel; ethanol; dimethyl ether; etc. [0027] The planetary transmission 14 includes an input member 17 continuously connected with the engine 12, a planetary gear arrangement 18, and an output member 19 continuously connected with the final drive mechanism 16. The planetary gear arrangement 18 includes four planetary gear sets 20, 30, 40 and 50. [0028] The planetary gear set 20 includes a sun gear member 22, a ring gear member 24, and a planet carrier assembly member 26. The planet carrier assembly member 26 includes a plurality of pinion gears 27 rotatably mounted on a carrier member 29 and disposed in meshing relationship with both the sun gear member 22 and the ring gear member 24. [0029] The planetary gear set 30 includes a sun gear member 32, a ring gear member 34, and a planet carrier assembly member 36. The planet carrier assembly member 36 includes a plurality of pinion gears 37 rotatably mounted on a carrier member 39 and disposed in meshing relationship with both the sun gear member 32 and the ring gear member 34. [0030] The planetary gear set 40 includes a sun gear member 42, a ring gear member 44, and a planet carrier assembly member 46. The planet carrier assembly member 46 includes a plurality of pinion gears 47 mounted on a carrier member 49 and disposed in meshing relationship with both the ring gear member 44 and the sun gear member 42. [0031] The planetary gear set 50 includes a sun gear member 52, a ring gear member 54, and a planet carrier assembly member 56. The planet carrier assembly member 56 includes a plurality of pinion gears 57, 58 mounted on a carrier member 59. The pinion gears 58 are disposed in meshing relationship with the ring gear member 54 and the pinion gears 57 are disposed in meshing relationship with both the sun gear member 52 and the respective pinion gear 58. [0032] The planetary gear arrangement also includes six torque-transmitting devices 80, 82, 84, 85, 86 and 87. The torque-transmitting devices 80 and 82 are stationary-type torque- transmitting devices, commonly termed brakes or reaction clutches. The torque-transmitting devices 84, 85, 86 and 87 are rotating-type torque-transmitting devices, commonly termed clutches. [0033] The input member 17 is continuously connected with the sun gear member 52 of the planetary gear set 50. The output member 19 is continuously connected with the ring gear member 44 of the planetary gear set 40. [0034] A first interconnecting member 70 continuously connects the ring gear member 24 of the planetary gear set 20 with the planet carrier assembly member 36 of the planetary gear set 30. A second interconnecting member 72 continuously connects the ring gear member 34 of the planetary gear set 30 with the planet carrier assembly member 46 of the planetary gear set 40 and with the ring gear member 54 of the planetary gear set 50. A third interconnecting member 74 continuously connects the sun gear member 22 of the planetary gear set 20 with the sun gear member 42 of the planetary gear set 40. [0035] A first torque-transmitting device, such as brake 80, selectively connects the sun gear member 22 of the planetary gear set 20 and the sun gear member 42 of the planetary gear set 40 via interconnecting member 74 with the transmission housing 60. A second torque- transmitting device, such as brake 82, selectively connects the planet carrier assembly member 56 of the planetary gear set 50 with the transmission housing 60. A third torque-transmitting device, such as clutch 84, selectively connects the sun gear member 22 of the planetary gear set 20 and the sun gear member 42 of the planetary gear set 40 via interconnecting member 74 with the sun gear member 32 of the planetary gear set 30. A fourth torque-transmitting device, such as clutch 85, selectively connects the planet carrier assembly member 26 of the planetary gear set 20 with the sun gear member 52 of the planetary gear set 50. A fifth torque- transmitting device, such as clutch 86, selectively connects the planet carrier assembly member 26 of the planetary gear set 20 with the planet carrier assembly member 56 of the planetary gear set 50. A sixth torque-transmitting device, such as clutch 87, selectively connects the ring gear member 34 of the planetary gear set 30, planet carrier assembly member 46 of the planetary gear set 40 and sun gear member 54 of the planetary gear set 50 via interconnecting member 72 with the sun gear member 32 of the planetary gear set 30. [0036] As shown in Figure 1b, and in particular the truth table disclosed therein, the torque-transmitting devices are selectively engaged in combinations of three to provide nine forward speed ratios and one reverse speed ratio, all with single transition shifts with three overdrive ratios. [0037] As set forth above, the engagement schedule for the torque-transmitting devices is shown in the truth table of Figure 1b. The chart of Figure lb describes the ratio steps that are attained in the above described transmission. For example, the step ratio between the first and second forward speed ratios is 1.32, while the step ratio between the reverse speed ratio and first forward ratio is -0.75. [0038] Referring to Figure 1c, the embodiment of powertrain 10 depicted in Fig. la is illustrated in a lever diagram format. A lever diagram is a schematic representation of the components of a mechanical device such as an automatic transmission. Each individual lever represents a planetary gearset, wherein the three basic mechanical components of the planetary gear are each represented by a node. Therefore, a single lever contains three nodes: one for the sun gear member, one for the planet gear carrier member, and one for the ring gear member. The relative length between the nodes of each lever can be used to represent the ring- to-sun ratio of each respective gearset. These lever ratios, in turn, are used to vary the gear ratios of the transmission in order to achieve appropriate ratios and ratio progression. Mechanical couplings or interconnections between the nodes of the various planetary gear sets are illustrated by thin, horizontal lines and torque transmitting devices such as clutches and brakes are presented as interleaved fingers. If the device is a brake, one set of the fingers is grounded. Further explanation of the format, purpose and use of lever diagrams can be found in SAE Paper 810102, authored by Benford, Howard and Leising, Maurice, "The Lever Analogy: A New Tool in Transmission Analysis", 1981, which is hereby fully incorporated by reference. [0039] The powertrain 10 includes an input member 17 continuously connected with the engine 12, an output member 19 continuously connected with the final drive mechanism 16, a first planetary gear set 20A having three nodes: a first node 22A, a second node 26A and a third node 24A; a second planetary gear set 30A having three nodes: a first node 32A, a second node 36A and a third node 34A; a third planetary gear set 40A having three nodes: a first node 42A, a second node 46A and a third node 44A; and a fourth planetary gear set 50A having three nodes: a first node 52A, a second node 56A and a third node 54A. [0040] The input member 17 is continuously connected with the node 52A. The output member 19 is continuously connected with the node 44A. [0041] The node 24A is continuously connected with the node 36A via interconnecting member 70. The node 34A is continuously connected with the nodes 46A and 54A via interconnecting member 72. The node 22A is continuously connected with node 42A via interconnecting member 74. [0042] A first torque-transmitting device, such as brake 80, selectively connects the nodes 22A and 42A via interconnecting member 74 with the transmission housing 60. A second torque-transmitting device, such as brake 82, selectively connects the node 56A with the transmission housing 60. A third torque-transmitting device, such as clutch 84, selectively connects the node 32A with the nodes 42A and 22A via interconnecting member 74. A fourth torque-transmitting device, such as clutch 85, selectively connects the node 26A with the node 52A. A fifth torque-transmitting device, such as clutch 86, selectively connects the node 26A with the node 56A. A sixth torque-transmitting device, such as clutch 87, selectively connects the node 32A with the nodes 34A, 46A and 54A via interconnecting member 72. [0043] To establish ratios, three torque-transmitting devices are engaged for each gear state. The engaged torque-transmitting devices are represented by an "X" in each respective row of Fig. 1b. For example, to establish reverse gear, the brake 82 and clutches 84 and 85 are engaged. The brake 82 engages the node 56A with the transmission housing 60. The clutch 84 engages the nodes 22A and 42A via interconnecting member 74 with node 32A. The clutch 85 engages the node 26A with the node 52A. Likewise, the nine forward ratios are achieved through different combinations of clutch engagement as per Figure lb. [0044] The powertrain 10 may share components with a hybrid vehicle, and such a combination may be operable in a "charge-depleting mode". For purposes of the present invention, a "charge-depleting mode" is a mode wherein the vehicle is powered primarily by an electric motor/generator such that a battery is depleted or nearly depleted when the vehicle reaches its destination. In other words, during the charge-depleting mode, the engine 12 is only operated to the extent necessary to ensure that the battery is not depleted before the destination is reached. A conventional hybrid vehicle operates in a "charge-sustaining mode", wherein if the battery charge level drops below a predetermined level (e.g., 25%) the engine is automatically run to recharge the battery. Therefore, by operating in a charge-depleting mode, the hybrid vehicle can conserve some or all of the fuel that would otherwise be expended to maintain the 25% battery charge level in a conventional hybrid vehicle. It should be appreciated that a hybrid vehicle powertrain is preferably only operated in the charge-depleting mode if the battery can be recharged after the destination is reached by plugging it into an energy source. [0045] While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims. CLAIMS 1. A multi-speed transmission comprising: an input member; an output member; first, second, third and fourth planetary gear sets each having first, second and third members; a first interconnecting member continuously connecting said third member of said first planetary gear set with said second member of said second planetary gear set; a second interconnecting member continuously connecting said third member of the second planetary gear set with said second member of said third planetary gear set and with said third member of said fourth planetary gear set; a third interconnecting member continuously connecting said first member of said first planetary gear set with said first member of said third planetary gear set; and six torque-transmitting devices for selectively interconnecting said members of said planetary gear sets with a stationary member or with other members of said planetary gear sets, said six torque-transmitting devices being engaged in combinations of three to establish at least nine forward speed ratios and at least one reverse speed ratio between said input member and said output member. 2. The transmission of claim 1, wherein a first of said six torque- transmitting devices is operable for selectively connecting said first member of said first planetary gear set with said stationary member. 3. The transmission of claim 2, wherein a second of said six torque- transmitting devices is operable for selectively connecting said second member of said fourth planetary gear set with said stationary member. 4. The transmission of claim 3, wherein a third of said six torque- transmitting devices is operable for selectively connecting said first member of said first planetary gear set with said first member of said second planetary gear set. 5. The transmission of claim 4, wherein a fourth of said six torque- transmitting devices is operable for selectively connecting said second member of said first planetary gear set with said first member of said fourth planetary gear set. 6. The transmission of claim 5, wherein a fifth of said six torque- transmitting devices is operable for selectively connecting said second member of said first planetary gear set with said second member of said fourth planetary gear set. 7. The transmission of claim 6, wherein a sixth of said six torque- transmitting devices is operable for selectively connecting said third member of said second planetary gear set with said first member of said second planetary gear set. 8. The transmission defined in claim 1, wherein said first and second torque-transmitting devices comprise brakes, and said third, fourth, fifth and sixth torque- transmitting devices comprise clutches. 9. The transmission of claim 1, wherein said first, second and third members of said first, second, third and fourth planetary gear sets comprise a sun gear member, a planet carrier assembly member and a ring gear member, respectively. 10. The transmission of claim 1, wherein said input member is continuously connected with said first member of said fourth planetary gear set, and said output member is continuously connected with said third member of said third planetary gear set. 11. The transmission of claim 1, wherein said second member of said fourth planetary gear set is a double-pinion carrier. 12. A multi-speed transmission comprising: an input member; an output member; first, second, third and fourth planetary gear sets each having first, second and third members; said input member being continuously connected with said first member of said fourth planetary gear set; and said output member being continuously connected with said third member of said third planetary gear set; a first interconnecting member continuously connecting said third member of said first planetary gear set with said second member of said second planetary gear set; a second interconnecting member continuously connecting said third member of said second planetary gear set with said second member of said third planetary gear set and with said third member of said fourth planetary gear set; a third interconnecting member continuously connecting said first member of said first planetary gear set with said first member of said third planetary gear set; a first torque-transmitting device selectively connecting said first member of said first planetary gear set with a stationary member; a second torque-transmitting device selectively connecting said second member of said fourth planetary gear set with said stationary member; a third torque-transmitting device selectively connecting said first member of said first planetary gear set with said first member of said second planetary gear set; a fourth torque-transmitting device selectively connecting said second member of said first planetary gear set with said first member of said fourth planetary gear set; a fifth torque-transmitting device selectively connecting said second member of said first planetary gear set with said second member of said fourth planetary gear set; a sixth torque-transmitting device selectively connecting said third member of said second planetary gear set with said first member of said second planetary gear set; and said six torque-transmitting devices being engaged in combinations of three to establish at least nine forward speed ratios and at least one reverse speed ratio between said input member and said output member. 12. The transmission of claim 11, wherein said first, second and third members of said first, second, third and fourth planetary gear sets comprise a sun gear member, a planet carrier assembly member and a ring gear member, respectively. 13. A multi-speed transmission comprising: an input member; an output member; first, second, third and fourth planetary gear sets each having a sun gear member, planet carrier assembly member and ring gear member; said input member being continuously interconnected with said sun gear member of said fourth planetary gear set; and said output member being continuously interconnected with said ring gear member of said third planetary gear set; a first interconnecting member continuously connecting said ring gear member of said first planetary gear set with said planet carrier assembly member of said second planetary gear set; a second interconnecting member continuously connecting said ring gear member of said second planetary gear set with said planet carrier assembly member of said third planetary gear set and with said ring gear member of said fourth planetary gear set; a third interconnecting member continuously connecting said sun gear member of said first planetary gear set with said sun gear member of said third planetary gear set; a first torque-transmitting device selectively connecting said sun gear member of said first planetary gear set with a stationary member; a second torque-transmitting device selectively connecting said planet carrier assembly member of said fourth planetary gear set with said stationary member; a third torque-transmitting device selectively connecting said sun gear member of said first planetary gear set with said sun gear member of said second planetary gear set; a fourth torque-transmitting device selectively connecting said planet carrier assembly member of said first planetary gear set with said sun gear member of said fourth planetary gear set; a fifth torque-transmitting device selectively connecting said planet carrier assembly member of said first planetary gear set with said planet carrier assembly member of said fourth planetary gear set; a sixth torque-transmitting device selectively connecting said ring gear member of said second planetary gear set with said sun gear member of said second planetary gear set; and said six torque-transmitting devices being engaged in combinations of three to establish nine forward speed ratios and one reverse speed ratio between said input member and said output member. Dated this 28th day of MAY 2008 The transmission has a plurality of members that can be utilized in powertrains to provide nine forward speed ratios and one reverse speed ratio. The transmission includes four planetary gear sets, six torque-transmitting devices, and three fixed interconnections. The powertrain includes an engine and torque converter that is continuously connected to one of the planetary gear members and an output member that is continuously connected with another one of the planetary gear members. The six torque-transmitting devices provide interconnections between various gear members, and the transmission housing, and are operated in combinations of three to establish nine forward speed ratios and one reverse speed ratio.

Full Text

9-SPEED TRANSMISSION
TECHNICAL FIELD
[0001] The present invention relates to a power transmission having four planetary gear
sets that are controlled by six torque-transmitting devices to provide nine forward speed ratios
and one reverse speed ratio.
BACKGROUND OF THE INVENTION
[0002] Passenger vehicles include a powertrain that is comprised of an engine, multi-
speed transmission, and a differential or final drive. The multi-speed transmission increases
the overall operating range of the vehicle by permitting the engine to operate through its torque
range a number of times. The number of forward speed ratios that are available in the
transmission determines the number of times the engine torque range is repeated. Early
automatic transmissions had two speed ranges. This severely limited the overall speed range
of the vehicle and therefore required a relatively large engine that could produce a wide speed
and torque range. This resulted in the engine operating at a specific fuel consumption point
during cruising, other than the most efficient point. Therefore, manually-shifted (countershaft
transmissions) were the most popular.
[0003] With the advent of three- and four-speed automatic transmissions, the automatic
shifting (planetary gear) transmission increased in popularity with the motoring public. These
transmissions improved the operating performance and fuel economy of the vehicle. The
increased number of speed ratios reduces the step size between ratios and therefore improves
the shift quality of the transmission by making the ratio interchanges substantially
imperceptible to the operator under normal vehicle acceleration.
[0004] Six-speed transmissions offer several advantages over four- and five-speed
transmissions, including improved vehicle acceleration and improved fuel economy. While
many trucks employ power transmissions having six or more forward speed ratios, passenger

cars are still manufactured with three- and four-speed automatic transmissions and relatively
few five- or six-speed devices due to the size and complexity of these transmissions.
[0005] Seven-, eight- and nine-speed transmissions provide further improvements in
acceleration and fuel economy over six-speed transmissions. However, like the six-speed
transmissions discussed above, the development of seven-, eight- and nine-speed transmissions
has been precluded because of complexity, size and cost.
SUMMARY OF THE INVENTION
[0006] It is an object of the present invention to provide an improved transmission
having four planetary gear sets controlled to provide nine forward speed ratios and one reverse
speed ratio.
[0007] The transmission family of the present invention has four planetary gear sets,
each of which includes a first, second and third member, which members may comprise a sun
gear, a ring gear, or a planet carrier assembly member, in any order.
[0008] In referring to the first, second, third and fourth gear sets in this description and
in the claims, these sets may be counted "first" to "fourth" in any order in the drawing (i.e.,
left to right, right to left, etc.). Additionally, the first, second or third members of each gear
set may be counted "first" to "third" in any order in the drawing (i.e., top to bottom, bottom
to top, etc.) for each gear set.
[0009] Each carrier member can be either a single-pinion carrier member (simple) or a
double-pinion carrier member (compound). Embodiments with long pinions are also possible.
[0010] A first interconnecting member continuously connects the third member of the
first planetary gear set with the second member of the second planetary gear set.
[0011] A second interconnecting member continuously connects the third member of
the second planetary gear set with the second member of the third planetary gear set and with
the third member of the fourth planetary gear set.

[0012] A third interconnecting member continuously connects the first member of the
first planetary gear set with the first member of the third planetary gear set.
[0013] The input member is continuously connected with the first member of the fourth
planetary gear set. The output member is continuously interconnected with the third member
of the third planetary gear set.
[0014] A first torque-transmitting device, such as a brake, selectively connects the first
member of the first planetary gear set with a stationary member (transmission housing/casing).
[0015] A second torque-transmitting device, such as a brake, selectively connects the
second member of the fourth planetary gear set with a stationary member (transmission
housing/casing).
[0016] A third torque-transmitting device, such as a clutch, selectively connects the
first member of the first planetary gear set with the first member of the second planetary gear
set.
[0017] A fourth torque-transmitting device, such as a clutch, selectively connects the
second member of the first planetary gear set with the first member of the fourth planetary
gear set.
[0018] A fifth torque-transmitting device, such as a clutch, selectively connects the
second member of the first planetary gear set with the second member of the fourth planetary
gear set.
[0019] A sixth torque-transmitting device, such as a clutch, selectively connects the
third member of the second planetary gear set with the first member of the second planetary
gear set.
[0020] The six torque-transmitting devices are selectively engageable in combinations
of three to yield nine forward speed ratios and one reverse speed ratio.
[0021] A variety of speed ratios and ratio spreads can be realized by suitably selecting
the tooth ratios of the planetary gear sets.

[0022] The above features and other features and advantages of the present invention
are readily apparent from the following detailed description of the best modes for carrying out
the invention when taken in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIGURE la is a schematic representation of a powertrain including a planetary
transmission in accordance with the present invention;
[0024] FIGURE 1b is a truth table and chart depicting some of the operating
characteristics of the powertrain shown in Figure la; and
[0025] FIGURE 1c is a schematic representation of the powertrain of Figure la
depicted in lever diagram form.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0026] Referring to the drawings, there is shown in Figure la a powertrain 10 having a
conventional engine and torque converter 12, a planetary transmission 14, and a conventional
final drive mechanism 16. The engine 12 may be powered using various types of fuel to
improve the efficiency and fuel economy of a particular application. Such fuels may include,
for example, gasoline; diesel; ethanol; dimethyl ether; etc.
[0027] The planetary transmission 14 includes an input member 17 continuously
connected with the engine 12, a planetary gear arrangement 18, and an output member 19
continuously connected with the final drive mechanism 16. The planetary gear arrangement 18
includes four planetary gear sets 20, 30, 40 and 50.
[0028] The planetary gear set 20 includes a sun gear member 22, a ring gear member
24, and a planet carrier assembly member 26. The planet carrier assembly member 26
includes a plurality of pinion gears 27 rotatably mounted on a carrier member 29 and disposed
in meshing relationship with both the sun gear member 22 and the ring gear member 24.

[0029] The planetary gear set 30 includes a sun gear member 32, a ring gear member
34, and a planet carrier assembly member 36. The planet carrier assembly member 36
includes a plurality of pinion gears 37 rotatably mounted on a carrier member 39 and disposed
in meshing relationship with both the sun gear member 32 and the ring gear member 34.
[0030] The planetary gear set 40 includes a sun gear member 42, a ring gear member
44, and a planet carrier assembly member 46. The planet carrier assembly member 46
includes a plurality of pinion gears 47 mounted on a carrier member 49 and disposed in
meshing relationship with both the ring gear member 44 and the sun gear member 42.
[0031] The planetary gear set 50 includes a sun gear member 52, a ring gear member
54, and a planet carrier assembly member 56. The planet carrier assembly member 56
includes a plurality of pinion gears 57, 58 mounted on a carrier member 59. The pinion gears
58 are disposed in meshing relationship with the ring gear member 54 and the pinion gears 57
are disposed in meshing relationship with both the sun gear member 52 and the respective
pinion gear 58.
[0032] The planetary gear arrangement also includes six torque-transmitting devices 80,
82, 84, 85, 86 and 87. The torque-transmitting devices 80 and 82 are stationary-type torque-
transmitting devices, commonly termed brakes or reaction clutches. The torque-transmitting
devices 84, 85, 86 and 87 are rotating-type torque-transmitting devices, commonly termed
clutches.
[0033] The input member 17 is continuously connected with the sun gear member 52 of
the planetary gear set 50. The output member 19 is continuously connected with the ring gear
member 44 of the planetary gear set 40.
[0034] A first interconnecting member 70 continuously connects the ring gear member
24 of the planetary gear set 20 with the planet carrier assembly member 36 of the planetary
gear set 30. A second interconnecting member 72 continuously connects the ring gear member
34 of the planetary gear set 30 with the planet carrier assembly member 46 of the planetary
gear set 40 and with the ring gear member 54 of the planetary gear set 50. A third

interconnecting member 74 continuously connects the sun gear member 22 of the planetary
gear set 20 with the sun gear member 42 of the planetary gear set 40.
[0035] A first torque-transmitting device, such as brake 80, selectively connects the sun
gear member 22 of the planetary gear set 20 and the sun gear member 42 of the planetary gear
set 40 via interconnecting member 74 with the transmission housing 60. A second torque-
transmitting device, such as brake 82, selectively connects the planet carrier assembly member
56 of the planetary gear set 50 with the transmission housing 60. A third torque-transmitting
device, such as clutch 84, selectively connects the sun gear member 22 of the planetary gear
set 20 and the sun gear member 42 of the planetary gear set 40 via interconnecting member 74
with the sun gear member 32 of the planetary gear set 30. A fourth torque-transmitting device,
such as clutch 85, selectively connects the planet carrier assembly member 26 of the planetary
gear set 20 with the sun gear member 52 of the planetary gear set 50. A fifth torque-
transmitting device, such as clutch 86, selectively connects the planet carrier assembly member
26 of the planetary gear set 20 with the planet carrier assembly member 56 of the planetary
gear set 50. A sixth torque-transmitting device, such as clutch 87, selectively connects the ring
gear member 34 of the planetary gear set 30, planet carrier assembly member 46 of the
planetary gear set 40 and sun gear member 54 of the planetary gear set 50 via interconnecting
member 72 with the sun gear member 32 of the planetary gear set 30.
[0036] As shown in Figure 1b, and in particular the truth table disclosed therein, the
torque-transmitting devices are selectively engaged in combinations of three to provide nine
forward speed ratios and one reverse speed ratio, all with single transition shifts with three
overdrive ratios.
[0037] As set forth above, the engagement schedule for the torque-transmitting devices
is shown in the truth table of Figure 1b. The chart of Figure lb describes the ratio steps that
are attained in the above described transmission. For example, the step ratio between the first
and second forward speed ratios is 1.32, while the step ratio between the reverse speed ratio
and first forward ratio is -0.75.

[0038] Referring to Figure 1c, the embodiment of powertrain 10 depicted in Fig. la is
illustrated in a lever diagram format. A lever diagram is a schematic representation of the
components of a mechanical device such as an automatic transmission. Each individual lever
represents a planetary gearset, wherein the three basic mechanical components of the planetary
gear are each represented by a node. Therefore, a single lever contains three nodes: one for
the sun gear member, one for the planet gear carrier member, and one for the ring gear
member. The relative length between the nodes of each lever can be used to represent the ring-
to-sun ratio of each respective gearset. These lever ratios, in turn, are used to vary the gear
ratios of the transmission in order to achieve appropriate ratios and ratio progression.
Mechanical couplings or interconnections between the nodes of the various planetary gear sets
are illustrated by thin, horizontal lines and torque transmitting devices such as clutches and
brakes are presented as interleaved fingers. If the device is a brake, one set of the fingers is
grounded. Further explanation of the format, purpose and use of lever diagrams can be found
in SAE Paper 810102, authored by Benford, Howard and Leising, Maurice, "The Lever
Analogy: A New Tool in Transmission Analysis", 1981, which is hereby fully incorporated by
reference.
[0039] The powertrain 10 includes an input member 17 continuously connected with the
engine 12, an output member 19 continuously connected with the final drive mechanism 16, a
first planetary gear set 20A having three nodes: a first node 22A, a second node 26A and a
third node 24A; a second planetary gear set 30A having three nodes: a first node 32A, a
second node 36A and a third node 34A; a third planetary gear set 40A having three nodes: a
first node 42A, a second node 46A and a third node 44A; and a fourth planetary gear set 50A
having three nodes: a first node 52A, a second node 56A and a third node 54A.
[0040] The input member 17 is continuously connected with the node 52A. The output
member 19 is continuously connected with the node 44A.
[0041] The node 24A is continuously connected with the node 36A via interconnecting
member 70. The node 34A is continuously connected with the nodes 46A and 54A via

interconnecting member 72. The node 22A is continuously connected with node 42A via
interconnecting member 74.
[0042] A first torque-transmitting device, such as brake 80, selectively connects the
nodes 22A and 42A via interconnecting member 74 with the transmission housing 60. A
second torque-transmitting device, such as brake 82, selectively connects the node 56A with
the transmission housing 60. A third torque-transmitting device, such as clutch 84, selectively
connects the node 32A with the nodes 42A and 22A via interconnecting member 74. A fourth
torque-transmitting device, such as clutch 85, selectively connects the node 26A with the node
52A. A fifth torque-transmitting device, such as clutch 86, selectively connects the node 26A
with the node 56A. A sixth torque-transmitting device, such as clutch 87, selectively connects
the node 32A with the nodes 34A, 46A and 54A via interconnecting member 72.
[0043] To establish ratios, three torque-transmitting devices are engaged for each gear
state. The engaged torque-transmitting devices are represented by an "X" in each respective
row of Fig. 1b. For example, to establish reverse gear, the brake 82 and clutches 84 and 85
are engaged. The brake 82 engages the node 56A with the transmission housing 60. The
clutch 84 engages the nodes 22A and 42A via interconnecting member 74 with node 32A. The
clutch 85 engages the node 26A with the node 52A. Likewise, the nine forward ratios are
achieved through different combinations of clutch engagement as per Figure lb.
[0044] The powertrain 10 may share components with a hybrid vehicle, and such a
combination may be operable in a "charge-depleting mode". For purposes of the present
invention, a "charge-depleting mode" is a mode wherein the vehicle is powered primarily by an
electric motor/generator such that a battery is depleted or nearly depleted when the vehicle
reaches its destination. In other words, during the charge-depleting mode, the engine 12 is only
operated to the extent necessary to ensure that the battery is not depleted before the destination is
reached. A conventional hybrid vehicle operates in a "charge-sustaining mode", wherein if the
battery charge level drops below a predetermined level (e.g., 25%) the engine is automatically
run to recharge the battery. Therefore, by operating in a charge-depleting mode, the hybrid

vehicle can conserve some or all of the fuel that would otherwise be expended to maintain the
25% battery charge level in a conventional hybrid vehicle. It should be appreciated that a hybrid
vehicle powertrain is preferably only operated in the charge-depleting mode if the battery can be
recharged after the destination is reached by plugging it into an energy source.
[0045] While the best modes for carrying out the invention have been described in
detail, those familiar with the art to which this invention relates will recognize various
alternative designs and embodiments for practicing the invention within the scope of the
appended claims.

CLAIMS
1. A multi-speed transmission comprising:
an input member;
an output member;
first, second, third and fourth planetary gear sets each having first, second and
third members;
a first interconnecting member continuously connecting said third member of
said first planetary gear set with said second member of said second planetary gear set;
a second interconnecting member continuously connecting said third member of
the second planetary gear set with said second member of said third planetary gear set and with
said third member of said fourth planetary gear set;
a third interconnecting member continuously connecting said first member of
said first planetary gear set with said first member of said third planetary gear set; and
six torque-transmitting devices for selectively interconnecting said members of
said planetary gear sets with a stationary member or with other members of said planetary gear
sets, said six torque-transmitting devices being engaged in combinations of three to establish at
least nine forward speed ratios and at least one reverse speed ratio between said input member
and said output member.
2. The transmission of claim 1, wherein a first of said six torque-
transmitting devices is operable for selectively connecting said first member of said first
planetary gear set with said stationary member.
3. The transmission of claim 2, wherein a second of said six torque-
transmitting devices is operable for selectively connecting said second member of said fourth
planetary gear set with said stationary member.

4. The transmission of claim 3, wherein a third of said six torque-
transmitting devices is operable for selectively connecting said first member of said first
planetary gear set with said first member of said second planetary gear set.
5. The transmission of claim 4, wherein a fourth of said six torque-
transmitting devices is operable for selectively connecting said second member of said first
planetary gear set with said first member of said fourth planetary gear set.
6. The transmission of claim 5, wherein a fifth of said six torque-
transmitting devices is operable for selectively connecting said second member of said first
planetary gear set with said second member of said fourth planetary gear set.
7. The transmission of claim 6, wherein a sixth of said six torque-
transmitting devices is operable for selectively connecting said third member of said second
planetary gear set with said first member of said second planetary gear set.
8. The transmission defined in claim 1, wherein said first and second
torque-transmitting devices comprise brakes, and said third, fourth, fifth and sixth torque-
transmitting devices comprise clutches.
9. The transmission of claim 1, wherein said first, second and third
members of said first, second, third and fourth planetary gear sets comprise a sun gear
member, a planet carrier assembly member and a ring gear member, respectively.
10. The transmission of claim 1, wherein said input member is continuously
connected with said first member of said fourth planetary gear set, and said output member is
continuously connected with said third member of said third planetary gear set.

11. The transmission of claim 1, wherein said second member of said fourth
planetary gear set is a double-pinion carrier.
12. A multi-speed transmission comprising:
an input member;
an output member;
first, second, third and fourth planetary gear sets each having first, second and
third members;
said input member being continuously connected with said first member of said
fourth planetary gear set; and said output member being continuously connected with said third
member of said third planetary gear set;
a first interconnecting member continuously connecting said third member of
said first planetary gear set with said second member of said second planetary gear set;
a second interconnecting member continuously connecting said third member of
said second planetary gear set with said second member of said third planetary gear set and
with said third member of said fourth planetary gear set;
a third interconnecting member continuously connecting said first member of
said first planetary gear set with said first member of said third planetary gear set;
a first torque-transmitting device selectively connecting said first member of
said first planetary gear set with a stationary member;
a second torque-transmitting device selectively connecting said second member
of said fourth planetary gear set with said stationary member;
a third torque-transmitting device selectively connecting said first member of
said first planetary gear set with said first member of said second planetary gear set;
a fourth torque-transmitting device selectively connecting said second member
of said first planetary gear set with said first member of said fourth planetary gear set;

a fifth torque-transmitting device selectively connecting said second member of
said first planetary gear set with said second member of said fourth planetary gear set;
a sixth torque-transmitting device selectively connecting said third member of
said second planetary gear set with said first member of said second planetary gear set; and
said six torque-transmitting devices being engaged in combinations of three to
establish at least nine forward speed ratios and at least one reverse speed ratio between said
input member and said output member.
12. The transmission of claim 11, wherein said first, second and third
members of said first, second, third and fourth planetary gear sets comprise a sun gear
member, a planet carrier assembly member and a ring gear member, respectively.
13. A multi-speed transmission comprising:
an input member;
an output member;
first, second, third and fourth planetary gear sets each having a sun gear member,
planet carrier assembly member and ring gear member;
said input member being continuously interconnected with said sun gear member
of said fourth planetary gear set; and said output member being continuously interconnected
with said ring gear member of said third planetary gear set;
a first interconnecting member continuously connecting said ring gear member
of said first planetary gear set with said planet carrier assembly member of said second
planetary gear set;
a second interconnecting member continuously connecting said ring gear
member of said second planetary gear set with said planet carrier assembly member of said
third planetary gear set and with said ring gear member of said fourth planetary gear set;

a third interconnecting member continuously connecting said sun gear member
of said first planetary gear set with said sun gear member of said third planetary gear set;
a first torque-transmitting device selectively connecting said sun gear member of
said first planetary gear set with a stationary member;
a second torque-transmitting device selectively connecting said planet carrier
assembly member of said fourth planetary gear set with said stationary member;
a third torque-transmitting device selectively connecting said sun gear member
of said first planetary gear set with said sun gear member of said second planetary gear set;
a fourth torque-transmitting device selectively connecting said planet carrier
assembly member of said first planetary gear set with said sun gear member of said fourth
planetary gear set;
a fifth torque-transmitting device selectively connecting said planet carrier
assembly member of said first planetary gear set with said planet carrier assembly member of
said fourth planetary gear set;
a sixth torque-transmitting device selectively connecting said ring gear member
of said second planetary gear set with said sun gear member of said second planetary gear set;
and
said six torque-transmitting devices being engaged in combinations of three to
establish nine forward speed ratios and one reverse speed ratio between said input member and
said output member.
Dated this 28th day of MAY 2008

The transmission has a plurality of members that can be utilized in powertrains to provide nine forward speed ratios and one reverse speed ratio. The transmission includes four planetary gear sets, six torque-transmitting devices, and three fixed interconnections. The powertrain includes an engine and torque converter that is continuously connected to one of the
planetary gear members and an output member that is continuously connected with another one
of the planetary gear members. The six torque-transmitting devices provide interconnections
between various gear members, and the transmission housing, and are operated in combinations of three to establish nine forward speed ratios and one reverse speed ratio.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=YRJ9MjBKJoUv6O/ueQhLdQ==&loc=wDBSZCsAt7zoiVrqcFJsRw==

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Patent Number

270382

Indian Patent Application Number

946/KOL/2008

PG Journal Number

51/2015

Publication Date

18-Dec-2015

Grant Date

16-Dec-2015

Date of Filing

28-May-2008

Name of Patentee

GM GLOBAL TECHNOLOGY OPERATIONS, INC.

Applicant Address

300 RENAISSANCE CENTER, DETROIT, MICHIGAN

Inventors:

#	Inventor's Name	Inventor's Address
1	ANDREW W. PHILLIPS	1052 CUTLER CIRCLE SALINE, MICHIGAN 48176
2	JAMES M. HART	16011 HAGGERTY, BELLEVILLE, MICHIGAN 48111
3	CLINTON E. CAREY	215 RIVERVIEW AVENUE, MONROE, MICHIGAN 48162
4	SCOTT H. WITTKOPP	6189 OAKHURST DRIVE, YPSILANTI, MICHIGAN 48197

PCT International Classification Number

F16D 23/00; F16H 3/34

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	11/774856	2007-07-09	U.S.A.