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 device for controlling overspeeding of automobiles
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
Mr. Shankar Kamanna Kengar, Mr. Srinivasan Govindarajan, Mr. Deepak Suryakant
Kulkami, Mr. Sadagopan Krishnan all 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 Complete specification particularly describes the invention and the manner in
which it is to be performed. —

FIELD OF INVENTION
This invention relates to a device for controlling overspeeding of automobiles. This device may be connected to carbureted engines, which do not include any other means for limiting speed. This device may also be attached to carbureted engines running on mono and bifuels like gasoline and CNG and gasoline and LPG.
BACKGROUND OF INVENTION
Unlike multipoint fuel injection engines and diesel engines, carbureted engines do not have speed control unit as an integral part of their design. Carbureted engines now find applications with alternate fuels such as CNG and LPG. The present trend is for high speed engines and highly offensive driving practice practiced by many city drivers, maximum speed limit and speed control of vehicles become an essential and life saving feature.
OBJECTS OF INVENTION
The main object of this invention is to limit engine speed at the desired and preset maximum, which is achieved by both operating and fuel controls governed by an electronic speed control means. This not only avoids overspeeding and resultant problems but also increases the engine life and fuel efficiency.

BRIEF DESCRIPTION OF INVENTION
This invention relates to a device for controlling overspeeding of automobiles which comprises an electronic over speed control unit connected to the engine of the automobile said unit having a signal receiving input means, an output means, said input means connected to a predetermined set of speed limits, a set of first electronic switches capable of triggering misfire in the first, second and third cylinders of the combustion engine sequentially to momentarily reduce the engine speed, means to monitor the misfire in the cylinder and atleast one switch to stop fuel supply to the engine when the predetermined speed limit exceeds said speed control unit being capable of deactuating the first series of electronic switches to restart the engine.
DETAILED DESCRIPTION OF INVENTION
Detailed description of the device for controlling overspeed is given below in comparison with the existing systems.
Fig 1 of the accompanying drawings shows a schematic block diagram of the existing carbureted engine. The Engine (E), Coil (C) and Distributor (D) which are an integral part of a typical carbureted system and these are identified by text nomenclature. In addition the system comprises of a throttle (1) connected to a carburetor (2) in air flow path. Feed pump relay (3) is an electrically operated solenoid valve which controls the fuel supply to fuel feed pump (4). High tension cables (5) connect the High tension end of the distributor to engine spark plug. Each spark plug is connected to distributor by a separate high tension cable.

The air and fuel quantity supplied to the engine governs the speed of the engine and that of the vehicle. The butterfly valve operated by the throttle thro' control linkage of the accelator pedal. Air and fuel supply to the engine is controlled by the opening of the butterfly valve. However in a carburetor engine fuel flow is governed by the carburetor which is proportionate to the air flow power produced by the ignition of air and fuel provides speed. The ignition system of the engine consists of ignition coil, distributor for controlling the ignition spark in the cylinders and spark plugs. It is understood that when the throttle is opened more, increased quantity fuel and air is supplied to the engine resulting in high speed.
The block diagram shown in Fig 2 represents the carbureted engine with the device according to this invention connected thereto. The system is similar to as shown in Fig 1 and in addition the system comprises of two electronic switches, ESI and ES2 represent a first switch and second electronic switches using power MOSFET. The engine over speed controller (EOSC) receives the engine speed signals from the engine as input through interface devices such as operational amplifiers to microcontroller and compares it with the predetermined maximum speed set point which is already programmed into the EOSC unit memory . When the engine speed is less than the set value of maximum speed, the unit remains inactive and no output signal is given. However, when the engine speed is equal or more than the set point, the electronic switch ESI is activated such that the ignition system generates misfire in one cylinder to reduce the power generated by the engine momentarily by tending to reduce the engine speed. This control unit is pre¬programmed in such a way that, if the engine speed still is more than the maximum pre set value, then in addition yet another cylinder is triggered to misfire to impart better control over the engine speed. If the engine speed is still more than the maximum preset value, then in addition to the first two cylinders the third cylinder is also triggered to generate for better engine speed control. This misfire is monitored for a pre determined time which is also programmable in the unit and if the time for which the misfire occurs

exceeds the programmed threshold, then, the engine overspeed control unit deactivates an electronic switch ES2 to stop the fuel supply to the engine. This is in addition to the misfire in the cylinders and is aimed at positive reduction in engine speed. Once the engine speed reaches below the pre-set value, ES2 is actuated to restart fuel supply. Simultaneously the misfire switches ESI is deactuated to stop misfire and the engine restores its normal operation.
The block diagram shown in Fig 3 is applicable to conventional gasoline engines run on compressed natural gas fuels wherein , Gas shut off solenoid (3') is an electrically solenoid operated valve which controls the gas supply to gas air mixer (4'). High tension cables (5) connect the high tension end of the distributor to spark plug mounted on the engine. Each spark plug is connected to distributor by a separate high tension cable. Pressure regulator (6) reduces the pressure of natural gas to atmospheric pressure , so that it can be inducted into the engine.
Fig 4 is a block diagram incorporating the speed control unit of this invention. The basic unit is same as that shown in the figure 3 and in addition to the parts described under Fig 3, system comprises of two electronic switches, ESI and ES2 which internally use power MOSFET representing the first switch and the second switch and a EOSC. The first switch is connected to distributor and the second switch is connected to gas shut off solenoid. The electronic switches receive the command signal from EOSC. When the engine speed is less than the set value of maximum speed, the unit remains inactive and no output signal is given. However, when the engine speed is equal or more than the set point, the electronic switch ESI is activated such that the ignition system generates misfire in one cylinder to reduce the power generated by the engine momentarily by tending to reduce the engine speed. This control unit is pre-programmed in such a way that, if the engine speed still is more than the maximum pre set value, then in addition yet another cylinder is triggered to misfire to impart better control over the engine speed. If

the engine speed is still more than the maximum preset value, then in addition to the first two cylinders the third cylinder is also triggered to generate for better engine speed control. This misfire is monitored for a pre determined time which is also programmable in the unit and if the time for which the misfire occurs exceeds the programmed threshold, then, the engine overspeed control unit deactivates an electronic switch ES2 to stop the gas supply to the engine. This is in addition to the misfire in the cylinders and is aimed at positive reduction in engine speed. Once the engine speed reaches below the pre-set value, ES2 is actuated to restart fuel supply. Simultaneously the misfire switches ESI is deactuated to stop misfire and the engine restores its normal operation
Fig 5 shows the diagram for Spark Ignition engine with bifuel operation with the engine over speed control for both the fuels. The system comprises of , engine, coil and distributor which are an integral part of a typical carbureted system and these are identified by text nomenclature. In addition the system comprises of a throttle (1) connected to a carburetor (2) in air flow path. Feed pump relay (3) is an electrically operated solenoid valve which controls the fuel supply to fuel feed pump (4). High tension cables (5) connect the High tension end of the distributor to engine spark plug. Each spark plug is connected to distributor by a separate high tension cable. Gas shut off solenoid (3') is an electrically operated solenoid valve which controls the gas supply to gas air mixer (4'). Pressure regulator (6) reduces the pressure of natural gas to atmospheric pressure, so that it can be inducted into the engine. . In addition the system comprises of three electronic switches, ESI and ES2 and ES2' which internally use power MOSFET representing the first switch, the second switch and the third switch respectively . The first switch (ESI) is connected to distributor and the second switch (ES2) is connected to fuel feed pump relay. The third switch (ES2')is connected to gas shut off solenoid. These three electronic switches receive the command signal from EOSC. When the system is running on gasoline and the engine speed is less than the set value of maximum speed, the unit remains inactive and no output signal is given.

However, when the engine speed is equal or more than the set point, the electronic switch ESI is activated such that the ignition system generates misfire in one cylinder to reduce the power generated by the engine momentarily by tending to reduce the engine speed. This control unit is pre-programmed in such a way that, if the engine speed still is more than the maximum pre set value, then in addition yet another cylinder is triggered to misfire to impart better control over the engine speed. If the engine speed is still more than the maximum preset value, then in addition to the first two cylinders the third cylinder is also triggered to generate for better engine speed control. This misfire is monitored for a pre determined time which is also programmable in the unit and if the time for which the misfire occurs exceeds the programmed threshold, then, the engine overspeed control unit deactivates an electronic switch ES2 to stop the fuel supply to the engine. This is in addition to the misfire in the cylinders and is aimed at positive reduction in engine speed. Once the engine speed reaches below the pre-set value, ES2 is actuated to restart fuel supply. Simultaneously the misfire switches ESI is deactuated to stop misfire and the engine restores its normal operation.
Similarly when the system is running on natural gas and the engine speed is less than the set value of maximum speed, the unit remains inactive and no output signal is given. However, when the engine speed is equal or more than the set point, the electronic switch ESI is activated such that the ignition system generates misfire in one cylinder to reduce the power generated by the engine momentarily by tending to reduce the engine speed. This control unit is pre-programmed in such a way that, if the engine speed still is more than the maximum pre set value, then in addition yet another cylinder is triggered to misfire to impart better control over the engine speed. If the engine speed is still more than the maximum preset value, then in addition to the first two cylinders the third cylinder is also triggered to generate for better engine speed control. This misfire is monitored for a pre determined time which is also programmable in the unit and if the time for which the misfire occurs exceeds the programmed threshold, then, the engine

overspeed control unit deactivates an electronic switch ES2' to stop the gas supply to the engine. This is in addition to the misfire in the cylinders and is aimed at positive reduction in engine speed. Once the engine speed reaches below the pre-set value, ES2' is actuated to restart fuel supply. Simultaneously the misfire switches ESI is deactuated to stop misfire and the engine restores its normal operation.
Distributor of the engine may be an electronic or mechanical distributor. Both mono fuel and bifuel operations can be controlled by this device and the fuels are gasoline, CNG and LPG either alone or in combination.

WE CLAIM
1. A device for controlling over speeding of automobiles comprising an electronic
control unit (EOSC) having input interface to receive speed signal from a engine and
output interfaces, said output interfaces connected to a first (ESl)and a second (ES2 or
ES2')electronic switch for controlling ignition and fuel injection system of said engine
respectively; said first electronic switch capable of triggering said ignition system to
progressively misfire in consecutive cylinders of the combustion engine to momentarily
reduce the engine speed when the engine speed is above pre-determined value, and said
second electronic switch de-actuatable to stop fuel supply to the engine when the engine
speed is above pre-determined value for a pre-determined time.
2. The device for controlling over speeding of automobiles as claimed in claim 1,
wherein said electronic control actuate said second electronic switch to supply fuel to the
engine when the speed limit is below the pre-determined value to restart the engine.
3. The device for controlling over speeding of automobiles as claimed in claim 1, wherein said ignition system consist of ignition coil, a distributor for controlling the ignition spark in the cylinders and spark plugs.
4. The device for controlling over speeding of automobiles as claimed in claim 5, wherein said distributor is an electronic or mechanical distributor.
Dated this 12th day of December 2006
TATA MOTORS LIMITED By their Agent and Attorney
Karuna Goleria of DePENNING & DePENNING