FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICTON
(See Section 10; rule 13)
TITLE OF THE INVENTION
Methodology for launching a hybrid vehicle and a system thereof
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001, Maharashtra, India
INVENTOR
Mr. Janardhanan Venkatapathi
Indian National
Of TATA MOTORS LIMITED.
an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001, Maharashtra, India
PREAMBLE TO THE DESCRIPTION The following specification describes the invention

FIELD OF THE INVENTION
The invention is related to a hybrid drivetrain for a vehicle and more particularly for vehicle launch.
BACKGROUND OF THE INVENTION
Launch of a hybrid vehicle by engine and assisted by a motor-generator, needs speed regulation of the engine and the motor-generator for preventing damage to the system. In case of vehicle launch purely by means of a motor-generator, or purely by the engine or a combination of these in a hybrid drivetrain, requires various clutching elements.
SUMMARY OF THE INVENTION
In accord with the invention, it is proposed to place a planetary gear drive, an electric motor-generator and at least one clutch between a driving machine and an automated manual / automatic transmission. The said planetary gear drive encompasses the elements like the sun gear, the internal gear, the planet carrier and staged planet gear sets. Of these elements, the internal gear meshes with staged planet secondary set and the sun gear meshes with staged planet primary set & is coupled with the electric motor-generator.. The transmission & the engine are connected to the planetary system. The electric motor-generator is of four quadrant type. A clutch is introduced for the lockup or bypass of the planetary gear drive. In an additional arrangement, an additional clutch is provided to disconnect the engine from the driveline. In an additional arrangement, a one way clutch or a lock is provided on the engine crank shaft or the input shaft to the planetary or the planet carrier to prevent its anticlockwise rotation for start-stop operation or for the Zero-Emission-Vehicle-operation, that is, powering the vehicle by the electric motor, when the internal combustion engine is not turning. A battery / electric energy storage device is provided for storing the electrical energy produced and reuse it when required.

BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example, with reference to the accompanying
drawings in which:
FIG. 1 is a sketch of the drive system according to the present invention.
FIG. 2 is a sketch of engine, transmission and motor-generator speeds, during the vehicle
launch mode.
FIG. 3A and 3B are sketches of the drive system according to the present invention, with a
clutch to decouple the engine from the input driveline.
FIG. 3C is a sketch of another embodiment of the drive system, with a clutch to decouple the
engine from the input driveline.
FIG. 4A and 4B are sketches of the drive system according to the present invention, with an
one way clutch / lock up clutch in the input driveline.
FIG. 4C is a sketch of another embodiment of the drive system, with an one way clutch / lock
up clutch in the input driveline.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same
FIG. I presents a sketch of the arrangement of the invented system. The prime mover engine (100) drives the crank shaft or flywheel (101). The crank shaft or flywheel (101) is connected to torsional damper system (102), which drives the Input Shaft (103). The Input Shaft (103) is connected to the planet carrier (104). The planet carrier (104) has at least one staged planet gear set (105). The staged planet gear set (105) is having planet primary gear (106) and planet secondary gear (107) which is integral with each other. The planet secondary gear (107) is smaller in diameter and has lesser number of teeth as compared to the planet primary gear (106). The planet primary gear (106) meshes with the sun gear (108), while the planet secondary gear (107) meshes with the internal gear (109). The sun gear (108) is connected to the motor-generator (111). The internal gear (109) is connected to the input shaft (112) of the transmission (113). The clutch (110) can couple and decouple the sun gear (108) with the

Input Shaft (103) / planet carrier (104) by closing and opening the clutch (110) respectively, thereby locking and unlocking the planetary system. In an alternate arrangement, a clutch similar to clutch (110) can couple and decouple the planet carrier (104) with the Internal gear (109) by closing and opening the clutch respectively, thereby locking and unlocking the planetary system. In an another alternate arrangement, a clutch similar to clutch (110) can couple and decouple the Internal Gear (109) with the sun gear (108) by closing and opening the clutch respectively, thereby locking and unlocking the planetary system.
Referring to Fig 1 and an example in FIG. 2, for vehicle launch by the engine with the clutch in open state, the motor-generator is in generator mode and while loading the generator, the vehicle gets launched. During launch by engine with the clutch open, while the vehicle is stationary (Transmission Input Shaft speed is zero), the engine speed is limited to the point when max torque is reached. This is to protect the motor-generator (IMG in FIG. 2) as the generator speeds are high. This control is relaxed when the vehicle starts moving, as the generator speeds drop with vehicle speed increase. Clutch can be closed when the generator speed and the engine speed match with the transmission speed, depending on the requirement at that situation.
During vehicle launch by engine, a part of the engine torque is consumed in the motor-generator, hence the 1st gear ratio of the transmission is deepened for compensation of restart grade ability purposes.
When the driver is accelerating or decelerating the engine, while in vehicle launch mode by engine and the driver is also applying the vehicle brakes, or in a condition when the vehicle is stationary and the vehicle brakes are applied and the transmission is in a gear and the clutch is open, the engine acceleration or deceleration is assisted by the motor-generator. This is because of the high reflected inertia of the motor-generator felt at the engine and also fuel efficiency.
Diesel engines generate peak torque at low speeds, hence the motor-generator speeds are not very high during the start of launch. However for petrol engines, the peak torque is generated at much higher engine speeds, which would result in very high motor-generator speeds during

start of launch, hence in such situations a launch by engine as in the afore mentioned method (FIG. 2) is not preferable. In such situations the scheme in FIG. 3A or 3B or 3C is preferred.
Referring to FIG. 3A, the prime mover engine (100) drives the crank shaft / flywheel (101). The crank shaft (101) is connected to torsional damper system (102), which drives the Input Shaft (103). The Input Shaft (103) is connected to the planet carrier (104). The planet carrier (104) has at least one staged planet gear set (105). The staged planet gear set (105) is made of planet primary gear (106) and planet secondary gear (107) which is integral with each other. The planet secondary gear (107) is smaller in diameter and has lesser number of teeth as compared to the planet primary gear (106).The planet primary gear (106) meshes with the sun gear (108), while the planet secondary gear (107) meshes with the internal gear (109). The sun gear (108) is connected to the motor-generator (111). The internal gear (109) is connected to the input shaft (112) of the transmission (113). The clutch (200) can couple and decouple the Input Shaft (103) with the torsional damper (102), thereby connecting and disconnecting respectively the Input Shaft (103) from the engine (100). The clutch (201) can couple and decouple the sun gear (108) with the Input Shaft (103) by closing and opening the clutch (201) respectively, thereby locking and unlocking the planetary system. In an alternate arrangement, a clutch similar to clutch (201) can couple and decouple the Internal gear (109) with the planet carrier (104) by closing and opening the clutch respectively, thereby locking and unlocking the planetary system. In an another alternate arrangement, a clutch similar to clutch (201) can couple and decouple the Internal gear (109) with the sun gear (108) by closing and opening the clutch respectively, thereby locking and unlocking the planetary system. After keeping open the clutch (200) and closing the clutch (201), the vehicle can be launched by the engine (100) by gradually closing the clutch (200). In another method, after keeping open the clutch (200) and closing the clutch (201), the vehicle can be launched by the motor-generator (111), while the engine (100) can be on or off. In another method, after keeping open the clutch (200) and closing the clutch (201), the vehicle can be launched both by the motor-generator (111) and the engine (100) by gradually closing the clutch (200).
Referring to FIG. 3B, the prime mover engine (300) drives the crank shaft / flywheel (101). The crank shaft (101) is connected to torsional damper system (102), which drives the Input Shaft (103). The Input Shaft (103) is connected to the planet carrier (104). The planet carrier (104) has at least one staged planet gear set (105). The staged planet gear set (105) is made of

planet primary gear (106) and planet secondary gear (107) which is integral with each other. The planet secondary gear (107) is smaller in diameter and has lesser number of teeth as compared to the planet primary gear (106). The planet primary gear (106) meshes with the sun gear (108), while the planet secondary gear (107) meshes with the internal gear (109). The sun gear (108) is connected to the motor-generator (111). The internal gear (109) is connected to the input shaft (112) of the transmission (113). The clutch (200) can couple and decouple the Input Shaft (103) with the torsional damper (102), thereby connecting and disconnecting respectively the Input Shaft (103) from the engine (100). The clutch (202) can couple and decouple the sun gear (108) with the carrier (104) by closing and opening the clutch (202) respectively, thereby locking and unlocking the planetary system. In an alternate arrangement, a clutch similar to clutch (202) can couple and decouple the Internal gear (109) with planet carrier (104) by closing and opening the clutch respectively, thereby locking and unlocking the planetary system. In an another alternate arrangement, a clutch similar to clutch (202) can couple and decouple the Internal gear (109) with the sun gear (108) by closing and opening the clutch respectively, thereby locking and unlocking the planetary system. After keeping open the clutch (200) and closing the clutch (202), the vehicle can be launched by the engine (100) by gradually closing the clutch (200). In another method, after keeping open the clutch (200) and closing the clutch (202), the vehicle can be launched by the motor-generator (111)), while the engine (100) can be on or off. In another method, after keeping open the clutch (200) and closing the clutch (202), the vehicle can be launched both by the motor-generator (111) and the engine (100) by gradually closing the clutch (200).
Referring to FIG. 3C, presents a sketch of another embodiment of the invented system. The prime mover engine (100) drives the crank shaft or flywheel (101). The crank shaft or flywheel (101) is connected to torsional damper system (102), which drives the Input shaft (103). The Input Shaft (103) is connected to the Internal gear (109). The planet carrier (104) has at least one staged planet gear set (105). The staged planet gear set (105) is having planet primary gear (106) and planet secondary gear (107) which is integral with each other. The planet secondary gear (107) is smaller in diameter and has lesser number of teeth as compared to the planet primary gear (106). The planet primary gear (106) meshes with the sun gear (108), while the planet secondary gear (107) meshes with the internal gear (109). The sun gear (108) is connected to the motor-generator (111). The planet carrier (104) is connected to the input shaft (112) of the transmission (113). The clutch (200) can couple and

decouple the Input Shaft (103) with the torsional damper (102), thereby connecting and disconnecting respectively the Input Shaft (103) from the engine (100). The clutch (203) can couple and decouple the sun gear (108) with the Internal gear (109) / Input Shaft (103) by closing and opening the clutch (203) respectively, thereby locking and unlocking the planetary system. In an alternate arrangement, a clutch similar to clutch (203) can couple and decouple the planet carrier (104) with the Internal gear (109) / Input Shaft (103) by closing and opening the clutch respectively, thereby locking and unlocking the planetary system. In an another alternate arrangement, a clutch similar to clutch (203) can couple and decouple the planet carrier (104) with the sun gear (108) by closing and opening the clutch respectively, thereby locking and unlocking the planetary system. After keeping open the clutch (200) & closing the clutch (203), the vehicle can be launched by the engine (100) by gradually closing the clutch (200). In another method, after keeping open the clutch (200) & closing the clutch (203), the vehicle can be launched by the motor-generator (111), while the engine (100) can be on or off. In another method, after keeping open the clutch (200) & closing the clutch (203), the vehicle can be launched both by the motor-generator (111) & the engine (100) by gradually closing the clutch (200).
The arrangement and methods explained above with reference to the figure 3A, 3B and 3C can be applied to diesel engines also.
Referring to FIG. 4A, the prime mover engine (100) drives the crank shaft or flywheel (101). The crank shaft or flywheel (101) is connected to torsional damper system (102), which drives the Input Shaft (103). The Input Shaft (103) is connected to the planet carrier (104). The planet carrier (104) has at least one staged planet gear set (105). The staged planet gear set (105) is having planet primary gear (106) and planet secondary gear (107) which is integral with each other. The planet secondary gear (107) is smaller in diameter and has lesser number of teeth as compared to the planet primary gear (106). The planet primary gear (106) meshes with the sun gear (108), while the planet secondary gear (107) meshes with the internal gear (109). The sun gear (108) is connected to the motor-generator (111). The internal gear (109) is connected to the input shaft (112) of the transmission (113). The clutch (110) can couple and decouple the sun gear (108) with the Input Shaft (103) by closing and opening the clutch (110) respectively, thereby locking and unlocking the planetary system. A one way clutch (301) connects the crank shaft (101) and a stationary housing (300). The one

way clutch (301) can also be a friction clutch or dog clutch or a simple lock. When it is needed to launch and drive the vehicle purely by the motor (111) and also using the planetary gears for motor torque multiplication or speed reduction, while the engine (100) is stationary, this one way clutch or friction clutch (301) at the engine crank shaft (101) prevents the crank shaft (101) from rotating anticlockwise direction so as to aid the motor (111) to launch and drive the vehicle for zero emission operation.
Referring to FIG. 4B, the prime mover engine (100) drives the crank shaft or flywheel (101). The crank shaft or flywheel (101) is connected to torsional damper system (102), which drives the Input Shaft (103). The Input Shaft (103) is connected to the planet carrier (104). The planet carrier (104) has at least one staged planet gear set (105). The staged planet gear set (105) is having planet primary gear (106) and planet secondary gear (107) which is integral with each other. The planet secondary gear (107) is smaller in diameter and has lesser number of teeth as compared to the planet primary gear (106). The planet primary gear (106) meshes with the sun gear (108), while the planet secondary gear (107) meshes with the internal gear (109). The sun gear (108) is connected to the motor-generator (111). The internal gear (109) is connected to the input shaft (112) of the transmission (113). The clutch (110) can couple and decouple the sun gear (108) with the Input Shaft (103) by closing and opening the clutch (110) respectively, thereby locking and unlocking the planetary system. A one way clutch (302) connects the carrier (104) and a stationary housing (300). The one way clutch (302) can also be a friction clutch or dog clutch or a simple lock. When it is needed to launch and drive the vehicle purely by the motor (111) and also using the planetary gears for motor torque multiplication or speed reduction, while the engine (100) is stationary, this one way clutch or friction clutch (302) at the carrier (104) prevents the carrier (104) from rotating anticlockwise direction so as to aid the motor (111) to launch and drive the vehicle for zero emission operation.
Referring to FIG. 4C, presents a sketch of another embodiment of the invented system. The prime mover engine (100) drives the crank shaft or flywheel (101). The crank shaft or flywheel (101) is connected to torsional damper system (102), which drives the Input Shaft (103). The Input Shaft (103) is connected to the Internal gear (109). The planet carrier (104) has at least one staged planet gear set (105). The staged planet gear set (105) is having planet

primary gear (106) and planet secondary gear (107) which is integral with each other. The planet secondary gear (107) is smaller in diameter and has lesser number of teeth as compared to the planet primary gear (106). The planet primary gear (106) meshes with the sun gear (108), while the planet secondary gear (107) meshes with the internal gear (109). The sun gear (108) is connected to the motor-generator (111). The planet carrier (104) is connected to the input shaft (112) of the transmission (113). The clutch (110) can couple and decouple the sun gear (108) with the Input Shaft (103) by closing and opening the clutch
(110) respectively, thereby locking and unlocking the planetary system. A one way clutch (303) connects the crank shaft (101) / Input Shaft (103) / internal gear (109) and a stationary housing (300). The one way clutch (303) can also be a friction clutch or dog clutch or a simple lock. When it is needed to launch and drive the vehicle purely by the motor (111) & also using the planetary gears for motor torque multiplication or speed reduction, while the engine (100) is stationary, this one way clutch or friction clutch (303) at the engine crank shaft (101) / Input Shaft (103) / internal gear (109) prevents the crank shaft (101) / Input Shaft (103) / internal gear (109) from rotating anticlockwise direction so as to aid the motor
(111) to launch and drive the vehicle for zero emission operation.
Where there is requirement that the engine (100) needs to be put on, or when a petrol engine is used, then an engine decouple clutch like mentioned in schemes of FIG. 3A or 3B or 3C is also necessary.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We claim:
1. A drive system for delivering power to driven wheels of a vehicle, the drive system
comprising:
an internal combustion engine;
a planetary gear system coupled to an output shaft of the internal combustion engine;
a motor-generator unit coupled to the planetary gear system;
a transmission system coupled between the planetary gear system and the driven wheels of the vehicle;
a first clutch configured to selectively couple and decouple the internal combustion engine from the drive system; and
a second clutch configured to selectively lock the planetary gear system, to bypass the planetary system function.
2. A drive system for delivering power to driven wheels of a vehicle, the drive system
comprising:
an internal combustion engine;
a planetary gear system coupled to an output shaft of the internal combustion engine;
a motor-generator unit coupled to the planetary gear system;
a transmission system coupled between the planetary gear system and the driven wheels of the vehicle;
a first clutch configured to selectively lock and unlock the internal combustion engine with a stationary housing; and
a second clutch configured to selectively lock the planetary gear system, to bypass the
planetary system function.
3. A drive system for delivering power to driven wheels of a vehicle, the drive system
comprising:
an internal combustion engine;
a planetary gear system having an internal gear and a planet carrier, the planetary gear system being coupled to an output shaft of the internal combustion engine; a motor-generator unit coupled to the planetary gear system;

a transmission system coupled between the planetary gear system and the driven wheels of the vehicle;
a third clutch configured to selectively lock and unlock the internal gear or the planet carrier with a stationary housing; and
a second clutch configured to selectively lock the planetary gear system, to bypass the
planetary system function.
4. The drive system as claimed in any one of the claims 1 - 3, wherein the planetary gear system includes a sun gear connected to the motor-generator unit.
5. The drive system as claimed in claim 4, wherein the planetary gear system further includes,
an internal gear connected to the transmission system ,and
a planet carrier connected to the internal combustion engine through an input shaft.
6. The drive system as claimed in claim 4, wherein the planetary gear system further
includes,
a planet carrier connected to the transmission system ,and
an internal gear connected to the internal combustion engine through an input shaft.
7. A method of launching a vehicle having a drive system as claimed in claim 1
comprising the steps of;
opening the first clutch;
closing the second clutch;
launching the vehicle by driving the motor generator.
8. A method of launching a vehicle having a drive system as claimed in claim 2 comprising
the steps of;
opening the second clutch;
closing the first clutch;
launching the vehicle by driving the motor generator.

9. A method of launching a vehicle having a drive system as claimed in claim 3 comprising the steps of;
opening the second clutch;
closing the third clutch;
launching the vehicle by driving the motor generator.