FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION A hybrid drive system
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 and the manner in which it is
to be performed.

FIELD OF THE INVENTION
The invention is related to a hybrid drivetrain for a vehicle. More specifically it is related to a hybrid drive system for delivering power.
BACKGROUND OF THE INVENTION
Drive systems for vehicles customarily comprise an internal combustion engine as the driving machine and a subsequent transmission. The transmission normally plays an important role in operating the engine in its efficient regions and also needs to efficiently transmit power to the wheels, resulting in better fuel economy. Conventionally additional motor-generator is used to operate the system and the engine for further efficiency improvement.
OBJECTS OF THE INVENTION
The main object of the invention is to develop a hybrid drive system for delivering power.
Another object of the invention is to operate the engine in its efficient region by making the transmission behave closer to CVT (Continuously Variable Transmission).
Another object of the invention is to have more efficiency than a CVT, with help of a motor-generator , an epicyclic unit and a clutch added in between an automated manual / automatic transmission and the internal combustion engine.
Another object of the invention is to provide an additional motor / generator that can be connected to the transmission output shaft.
SUMMARY OF THE INVENTION
Accordingly the present invention discloses a hybrid drive system for a vehicle comprising: a driving engine (100) having an output shaft (101); a motor generator (111); a planetary gear system having at least one staged planet gear set

(105) mounted on a planet carrier (104) coupled to the output shaft (101) of the driving engine (100); the said planetary gear system also having a first sun gear (108) and a second sun gear (109); the motor-generator (111) being coupled to the first sun gear (108); the said staged planet gear set (105) includes a first planet gear (106) and a second planet gear (107); the first planet gear (106)_meshes with the first sun gear (108) and the second planet gear (107) meshes with the second sun gear (109); the ratio of working pitch diameter of first planet gear (106) to the second planet gear (107) being greater than one; the ratio of working pitch diameter of the second sun gear (109) to the first sun gear (108) being greater than one, a transmission (113) coupled between the second sun gear (109) and driven wheels (401); and a clutch (110) configured to selectively lock the planetary gear system, to bypass the planetary gear system.
An envelope (115) is mounted on the input shaft (112) of the transmission (113), wherein the planetary gear system is enclosed in the said envelope (115) which contains the lubricating oil for the planetary unit. The system is having an engine braking arrangement (114) or retarding arrangement. The braking arrangement (114) is adapted to control the speed of the engine (100).
The braking arrangement (114) is an exhaust brake or a friction brake or fluid pump, or electric brake or a combination thereof. The system along with a motor-generator (111) and an epicyclic unit is configured for achieving improved efficiency than a CVT (Continuously Variable Transmission),
The system is configured to add a planetary system, a clutch (110) and an electric motor-generator (111) in between an automated manual/automatic transmission (113) and the internal combustion engine (100).
The system is configured to connect an additional motor / generator (400) to the transmission output shaft either directly or through a gear drive. The system is configured such that the additional motor-generator (400) drives or get driven by the transmission output/the vehicle wheels (401).
The said additional motor/generator (400) is configured to drive the transmission output/vehicle wheels (401) during the gear shift operation to aid in gear shifting

without power interruption, provides power for vehicle acceleration, launch, drive and supports vehicle braking or coasting.
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. 1 A is a perspective schematic view of the planetary system used in the drive
system according to the present invention.
FIG. 2 is a sketch of the drive system according to the present invention with an
additional motor-generator at the output end of the transmission
BRIEF DESCRIPTION OF THE INVENTION
The present invention discloses hybrid drivetrain for a vehicle. More specifically it is related to a hybrid drive system for delivering power.
To operate the engine in its efficient region by making the transmission behave closer to CVT (Continuously Variable Transmission), and to have more efficiency than a CVT, a motor-generator, an epicyclic unit / planetary gear system and a clutch are added in between an automated manual / automatic transmission and the internal combustion engine
The hybrid drive system contains a planetary gear system having a first and a second sun gears, a planet' carrier and at least one staged planet gear set. The staged planet gear set includes a first planet gear and a second planet gear. Of these elements, the second sun gear meshes with second planet of staged planet gear set and the first sun gear meshes with first planet of staged planet gear set and is coupled with the electric motor-generator. The transmission is connected to the second sun gear and the engine is connected to the planet carrier. The electric motor-generator is of four quadrant type. A clutch is introduced for the lockup or bypass of the planetary gear drive. An additional motor / generator can be connected to the transmission output shaft / wheels to provide power for vehicle acceleration, launch, drive and supports vehicle braking or coasting and aids in

gear shifting without power interruption, by driving the vehicle momentarily during gear shift operation.
A battery / electric energy storage device is provided for storing the electrical energy produced and reuse it when required.
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. 1 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 / engine output 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 atleast one staged planet gear set (105). The staged planet gear set (105) is having first planet gear (106) and second planet gear (107) which is integral with each other. The ratio of working pitch diameters of first planet gear (106) to second planet gear (107) is greater than 1. The planetary system has a first sun gear (108) and second sun gear (109). The ratio of working pitch diameters of second sun gear (109) to first sun gear (108) is greater than I. The first planet gear (106) meshes with the first sun gear (108), while the second planet gear (107) meshes with the second sun gear (109). The first sun gear (108) drives or gets driven by the motor-generator (111). The motor-generator (111) is directly coupled to the first sun gear (108). In an another embodiment of the present disclosure, the motor-generator (111) is rotationally coupled to the first sun gear (108) through a gear drive. The second sun gear (109) is connected to the input shaft (112) of the transmission (113). The clutch (110) can couple and decouple the first 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 second sun 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 second sun Gear (109) with the first sun gear (108) by closing and opening the clutch respectively, thereby locking and unlocking the planetary system. The clutch (110) can be friction clutch or a dog clutch. In-an embodiment of the present invention the planetary gear system may have one or more than one staged planet gear set. The envelope (115) mounted on the transmission input shaft (112) encompasses all elements the planetary unit and contains lubricating oil for the planetary unit. The drive system has a braking arrangement (114) for controlling the speed of the engine for better efficiency of the drive system. The braking arrangement (114) can be an exhaust brake or a friction brake or any auxiliary equipment acting as a brake or fluid pump or electric brake etc or a combination all these brakes to retard the engine to assist the vehicle braking.
FIG. 1A presents a perspective schematic view of the planetary system used in the drive system according to the present invention.
Referring to FIG. 1, when the clutch (110) is opened, the engine is directly driving only the Input shaft (103),, the first sun gear (108) can have same or different speed as that of the engine (100). In this condition the motor-generator (111) and hence the speed of the first sun gear (108) is maintained very low or zeTo by controlling the motor-generator. This will result in the speed of the second sun gear (109) and hence the speed of the transmission input shaft (112) becoming less than the speed of the engine (100) to have a lower speed of transmission output. 'R' is the ratio of speed of the engine (100) to the speed of transmission input shaft (112) in the above mentioned situation, that is when the speed of the first sun gear (108) is zero and the clutch (110) is open. In actual operation, it is advisable to operate the motor-generator (111) at speeds above zero (for example 100 rpm) that is clockwise (same direction as engine), or slightly below zero (for example -100 rpm) that is counterclockwise, for purposes of supplementing the engine power or charging the battery during vehicle driving and also for efficient operation of the system. The planetary gear ratio and hence the ratio R should be such that while operation of the transmission in a particular gear, will result in a drive ratio (ratio of engine output speed to transmission output speed) which is in between the ratios of the current gear and next lower gear of the transmission. For

example, when the transmission is in 2nd gear, the transmission output speed will become closer to a speed in between the 2nd gear and the 1st gear speeds, because of the ratio R. In clutch closed condition, the transmission output speed would be equal to 2n gear speed, because the speeds of the motor-generator, the engine and the transmission input shaft are same in clutch closed condition. In effect if a 6 speed transmission is used, the effective speeds available with this arrangement is 12 speeds. These multiple gear ratio options can help in operating the engine in its efficient regions like a CVT. Operating the motor-generator (111) in low speeds also minimizes the power of the motor-generator (111) hence improves the fuel economy of the drive system.
Referring to FIG. 2, presents a sketch of another embodiment of the invented system with an additional motor / generator connected at the transmission output. The additional motor-generator (400) drives or gets driven by the transmission output / the vehicle wheels (401). The additional motor-generator (400) is directly coupled to the transmission output. In an another embodiment of the present disclosure, the additional motor-generator (400) is rotationally coupled to the transmission output through a gear drive. The additional motor / generator (400) drives the transmission output / vehicle wheels (401) during the gear shift operation and provides power for vehicle acceleration, launch, drive and supports vehicle braking or coasting. Thus the additional motor-generator (400) aids in gear shifting without power interruption, by driving the vehicle momentarily during gear shift operation.
Part list
The major components of the drive system according to the present invention are described below:
100 Prime mover engine
101 Crank shaft or engine output shaft or fly wheel
102 Torsional damper system
103 Input shaft
104 planet carrier

105 Staged Planet gear set
106 first planet gear
107 Second planet gear
108 First sun gear
109 Second sun gear
110 Clutch
111 Motor-generator
112 Input shaft of Transmission
113 Transmission
114 braking arrangement
115 envelop

400 Additional motor-generator
401 transmission output / vehicle wheels
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 hybrid drive system for a vehicle comprising:
a driving engine (100) having an output shaft (101);
a motor generator (111);
a planetary gear system having at least one staged planet gear set (105) mounted on a planet carrier (104) coupled to the output shaft (101) of the driving engine (100); the said planetary gear system also having a first sun gear (108) and a second sun gear (109); the motor-generator (111) being coupled to the first sun gear (108); the said staged planet gear set (105) includes a first planet gear (106) and a second planet gear (107); the first planet gear (106)_meshes with the first sun gear (108) and the second planet gear (107) meshes with the second sun gear (109); the ratio of working pitch diameter of first planet gear (106) to the second planet gear (107) being greater than one; the ratio of working pitch diameter of the second sun gear (109) to the first sun gear (108) being greater than one,a transmission (113) coupled between the second sun gear (109) and driven wheels (401); and
a clutch (110) configured to selectively lock the planetary gear system, to bypass the planetary gear system.
2. The drive system as claimed in preceding claims further comprising an envelope (115)_mounted on the input shaft (112) of the transmission (113), wherein the planetary gear system is enclosed in the said envelope (115) which contains the lubricating oil for the planetary unit.
3. The drive system as claimed in any one of the preceding claims wherein the system is having an engine braking arrangement (114) or retarding arrangement.
4. The drive system as claimed in any one of the preceding claims wherein said braking arrangement (114) is adapted to control the speed of the engine (100).
5. The drive system as claimed in any one of the preceding claims wherein said braking arrangement (114) is an exhaust brake or a friction brake or fluid pump, or electric brake or an auxiliary equipment or a combination thereof.

6. The drive system as claimed in the preceding claims wherein the transmission
(113) in the said system is an automated manual/automatic transmission.
7. The drive system as claimed in the preceding claims wherein said system is configured to connect an additional motor / generator (400) to the transmission output shaft.
8. The drive system as claimed in the preceding claims wherein said system is configured to have the additional motor-generator (400) for driving or get driven by the transmission output/the vehicle wheels (401) by coupling to the transmission output through a gear drive.
9. The drive system as claimed in the preceding claims wherein said additional
motor/generator (400) is configured to provide power for vehicle acceleration,
launch, drive and supports vehicle braking or coasting and aids in gear shifting
without power interruption, by driving the vehicle / transmission output (401)
momentarily during gear shift operation.