FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
Improved Gear Shift System And Process of Gear Shifting 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
INVENTORS
Srinivasa Raju Gavarraju and Ashfaque Ahmed Ansari
both Indian Nationals
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 particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
This invention relates to gear shift systems used in vehicles and more particularly it relates to gear shift systems used in CVT (Continuously Variable Transmission) vehicles.
BACKGROUND OF INVENTION
The automotive vehicles typically employ a driver-operated mechanical gearshift assembly which controls the transmission. Such shifters generally employ a shift lever which is moved by hand between various gear settings (Forward, Neutral & Reverse). While such systems are widely used and some of the drawbacks associated with the said system are
1. The effort required in shifting the gear is more
2. Wear and tear of the components is high
3. It is very difficult to accommodate various safety interlocks like
(i) Prevention of vehicle leaping forward during cranking of engine.
(ii) Prevention of unintentional / accidental gearshifts from forward to
reverse and vice-versa when vehicle is in motion, (iii) Prevention of gear crash when gear-shifting and engine speed rising is done simultaneously.
In order to overcome the above said drawbacks, this invention is devised. The improved gearshift system in accordance with this invention is an electromechanical system that replaces the mechanical link between the transmission and the shift input lever. The shifting between the three driving positions, F (Forward), N (Neutral) and R (Reverse), is controlled electronically. The system comprises Sensors, Electronic Control Unit (ECU) and the Actuator motor. Actuator motor & gear position sensors, gearshift switch & gear indicator may be integrated in order to have a compact system.

The ECU receives signals from various sensors and based on these inputs, ECU will command the actuator motor to rotate in forward / reverse direction.
This invention ensures (i) that there is no leaping of vehicle when the engine is being cranked (ii) prevention of unintentional / accidental shifts and (iii) prevention of gear crash when gear-shifting and engine speed rising are done simultaneously.
OBJECTS OF INVENTION
The main object of this invention is to provide improved gearshift system which is able to give better safety to vehicle as well as occupants.
Yet another object of this invention is to provide improved gearshift system which is able to prevent vehicle leaping forward/reverse during cranking of engine.
Yet another object of this invention is to provide improved gearshift system which is able to prevent unintentional / accidental gearshifts from forward to reverse and vice-versa when vehicle is in motion.
Yet another object of this invention is to provide improved gearshift system which is able to prevent gear crash when gear-shifting and engine speed rising is done simultaneously.
Yet another object of this invention is to provide improved gearshift system which is able to provide current gear position display to the driver.

Yet another object of this invention is to provide improved process of gear shifting which will happen only when vehicle speed is zero and engine is at idle speed.
Yet another object of this invention is to provide improved gearshift system which is simple in construction, ease for operation and cost effective.
STATEMENT OF INVENTION
Improved gearshift system comprises gearbox, gearshift switch, electronic control unit (ECU), actuator motor, battery, gear position sensor, vehicle speed sensor, engine speed sensor and brake switch wherein said actuator motor is connected to gearbox; gearshift switch, gear position sensor, vehicle speed sensor, engine speed sensor, brake switch and battery are interfaced with the electronic control unit.
Process of gear shifting by improved gearshift system comprises:
a) Selecting the desired gear position;
b) Feeding signals from gear position sensor, vehicle speed sensor, engine speed sensor and brake switch to ECU;
c) Actuating the said actuator motor based on said feedback signals when all following conditions are satisfied
i. Vehicle speed is zero
ii. Engine is at idle speed
iii. Brake switch is in ON condition
Switching ON the indication of desired gear position.
BRIEF DESCRIPTION OF INVENTION
Improved gearshift system in accordance with this invention comprises;

gearbox, gearshift switch, electronic control unit (ECU), actuator motor, gear display unit, gearshift lever, battery, gear position sensor, vehicle speed sensor, engine speed sensor and brake switch.
Wherein actuator motor is connected to gearbox through the gearshift lever; gearshift switch, vehicle speed sensor, engine speed sensor, brake switch and battery are connected to the electronic control unit; gear display unit adapted to be mounted on the dashboard is interfaced with the electronic control unit.
When driver operates the gearshift switch, the commanded signal goes to the ECU and based on other inputs like gear position feedback signal, vehicle speed signal, engine speed signal & brake switch signal, the ECU commands the actuator motor to rotate in clockwise or anticlockwise direction so as to engage the gear in forward, neutral or reverse position.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 shows the line diagram of the improved gearshift system in accordance with this invention.
Figure 2 shows the pictorial representation of the improved gearshift system.
DETAILED DESCRIPTION OF INVENTION
Referring now to the drawing 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,
Referring to figure 1 and figure 2,

Improved gearshift system in accordance with this invention basically comprises Gearbox (6), Gearshift switch (1), Electronic Control Unit (2), Actuator motor (3), Gear display unit (4), Gearshift lever (5), Battery (7), Gear position sensor (8), Vehicle speed sensor (9), Engine speed sensor (10) and Brake switch (11). Wherein Actuator motor (3) is connected to Gearbox (6) through the Gearshift lever (5); Gearshift switch (1), Vehicle speed sensor (9), Engine speed sensor (10), Brake switch (11) and Battery (7) are connected to the Electronic Control Unit (2); Gear display unit (4) adapted to be mounted on the dashboard is interfaced with the Electronic Control Unit (2). Actuator motor (3) and said Gearbox (6) are provided with two or more mounting bosses to mount the said Actuator motor (3) on the said Gearbox (6).
The actuator motor has a pinion (12) on its output shaft (13) which engages with the gearshift lever. Actuator motor pinion rotation leads to the rotary motion of the gearshift lever (5) which in turn engages the gear in forward, neutral or reverse position.
Neutral position and brake switch signals are fed to the ECU. If vehicle is in neutral position and brake is applied, then only engine cranking will be enabled to ensure that the vehicle will not leap forward/reverse when the engine is being cranked.
Vehicle speed and engine speed signals are fed to the ECU. If the vehicle is moving in forward direction and accidentally if the gearshift switch is operated to reverse position, the gear will not shift until vehicle speed reaches zero and engine is at idle speed. Similar action will happen when the vehicle is moving in reverse direction and accidentally gearshift switch is operated to forward position.

Gear position feedback, engine speed signal and vehicle speed signals are fed to the ECU. If the engine speed is at idle and if vehicle speed is zero, then only gear-shifting will be enabled to prevent gear crashing if gearshift and engine speed rising is done simultaneously.
Process of gear shifting by improved gearshift system comprises: Selecting the desired gear position;
a) Feeding signals from gear position sensor, vehicle speed sensor, engine speed sensor and brake switch to ECU;
b) Actuating the said actuator motor based on said feedback signals when all following conditions are satisfied
iv. Vehicle speed is zero
v. Engine is at idle speed
vi. Brake switch is in ON condition
c) Switching ON the indication of desired gear position.
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. Improved gearshift system comprises gearbox, gearshift switch, electronic control unit, actuator motor, battery, gear position sensor, vehicle speed sensor, engine speed sensor and brake switch wherein said actuator motor is connected to gearbox; gearshift switch, gear position sensor, vehicle speed sensor, engine speed sensor, brake switch and battery are interfaced with electronic control unit.
2. Improved gearshift system as claimed in claim 1, wherein said system is further provided with gear display unit interfaced with the electronic control unit and is adapted to be mounted on the dashboard.
3. Improved gearshift system as claimed in claim 1, wherein said gearshift switch is integrated with gear display unit.
4. Improved gearshift system as claimed in claims 1 to 3, wherein said actuator motor is connected to gearbox through the gearshift lever.
5. Improved gearshift system as claimed in claims 1 to 4 wherein said actuator motor is mounted on said gearbox.
6. Improved gearshift system as claimed in claim 5 wherein said actuator motor and said gear box are provided with two or more mounting bosses to mount said actuator motor on said gearbox.
7. Improved gearshift system as claimed in claims 1 to 6, wherein said actuator motor is provided with a pinion on its output shaft to engage with gearshift lever.

8. Improved gearshift system as claimed in claims 1 to 7, wherein said gearshift lever is provided with external engagement means or internal engagement means to mesh with said pinion on said actuator motor.
9. Process of gear shifting by improved gearshift system as claimed in claims 1 to 8, comprises:

a) Selecting the desired gear position;
b) Feeding signals from gear position sensor, vehicle speed sensor, engine speed sensor and brake switch to ECU;
c) Actuating the said actuator motor based on said feedback signals when all following conditions are satisfied
i) Vehicle speed is zero
ii) Engine is at idle speed
iii) Brake switch is in ON condition
d) Switching ON the indication of desired gear position.
10. Improved gearshift system and process of gear shifting substantially as
herein described with reference to accompanying drawing.



ABSTRACT
Improved Gear Shift System And Process of Gear Shifting Thereof
This invention relates to improved gearshift system and process of gear
shifting. Improved gear shift system comprises gearbox, gearshift
switch, electronic control unit, actuator motor, gear display unit,
gearshift lever, battery, gear position sensor, vehicle speed sensor,
engine speed sensor and brake switch. Wherein actuator motor is
connected to gearbox through the gearshift lever; gearshift switch,
vehicle speed sensor, engine speed sensor, brake switch and battery are
connected to the electronic control unit; gear display unit adapted to be
mounted on the dashboard is interfaced with the electronic control unit.
When driver operates the gearshift switch, the commanded signal goes
to the ECU and based on other inputs like gear position feedback signal,
vehicle speed signal, engine speed signal and brake switch signal, the
ECU commands the actuator motor to rotate in clockwise or anti
clockwise direction so as to engage the gear in forward, neutral or