FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
TITLE OF THE INVENTION ENGINE SPEED CONTROL SYSTEM
APPLICANT
TATA MOTORS LIMITED
of Bombay House, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400 001,
Maharashtra, India;
an Indian company
INVENTORS
Mr. Hemant Ravan Pawar and Mr. Mithun Ravindra Chaskar
both are Indian Nationals of
TATA MOTORS LIMITED,
Bombay House, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400001,
Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the
manner in which it is to be performed.

This is a patent of Addition to Earlier filed Indian Application no. 953/MUM/2010 pertaining to subject matter titled "On the fly fuel efficiency control" and having a filing date of 30/03/2010
TECHNICAL FIELD
The present invention is directed to an engine management system for an internal combustion engine. In particular, this invention is directed to a system and a method that controls engine speed at the time of vehicle launch.
BACKGROUND OF DISCLOSURE
Different drivers may launch a vehicle in different ways. Some may be especially careful in conducting a launch; others, less so. Further, now a days, while driving vehicles in city driving conditions, particularly, in heavy traffic areas where bumper to bumper traffic condition has reached, the vehicle is launched more frequently. In such conditions, launching the vehicle at engaging gear greater than 1st gear and high engine speed can lead to more clutch wear due to increase in clutch temperature, more fuel consumption and vehicle power losses. One significant cause of accelerated clutch wear and tear is high engine speed at the time of launch. The high engine speed at the time of launch adversely affects the fuel economy of the vehicle.
Another concern with un-controlled vehicle launch is in terms of safety, when engine speed is more at the time of launching the vehicle at 1st gear or greater gear. In such cases, releasing the clutch paddle suddenly results in high acceleration which can result to a serious accidents, particularly, when the driver is unexperienced. Further, the accidents due to the vehicle getting out of control due to high engine speed at the time of launch are more frequent in case of bumper to bumper traffic conditions.
Accordingly, there is a need for controlled launch of vehicle.

OBJECTS OF THE DISCLOSURE
An object of the present disclosure is to provide a system for controlled launch of vehicle, thereby obviating drawbacks of uncontrolled vehicle launch.
An object of the present disclosure is to provide a system for controlled launch of vehicle based on essential parameters such as gradient of surface on which vehicle is travelling and gear selected.
Another object of the present disclosure is to provide a system and a method that controls engine speed at the time of vehicle launch, thereby improving clutch life and fuel economy.
Still another object of the present disclosure is to provide a system that controls engine speed at the time of vehicle launch that is simple, user friendly and eliminates the concerns associated with vehicle handled by inexperienced or rash drivers.
Yet another object of the present disclosure is to provide a system that controls engine speed at the time of vehicle launch to minimize the engine power losses.
Still another object of the present disclosure is to provide a system that controls engine speed at the time of vehicle launch and prevents major fatality during vehicle sudden launch at high engine speed conditions.
Another object of the present disclosure is to provide a system that controls engine speed at the time of vehicle launch that is reliable and accurate.
Still another object of the present disclosure is to provide an engine management system with flexibility to switch between controlled launch mode in which the engine speed at the time of launch of the vehicle is controlled and a user mode in which the vehicle launch is independent of engine speed.
SUMMARY
A system for controlling Engine speed of a vehicle at the time of launch of the vehicle is disclosed in accordance with an embodiment of the present disclosure. The system includes a gear position sensor, an engine speed sensor, at least one gradient sensor, a

mode selection switch and an Electronic Control Unit (ECU). The gear position sensor senses gear selected by a driver. The engine speed sensor senses the engine speed. The gradient sensor senses the gradient of the surface on which the vehicle is moving. The mode selection switch selects between a first mode and a second mode. The Electronic Control Unit (ECU) receive inputs from the gear position sensor, the engine speed sensor, the gradient sensor and the mode selection switch, wherein in first mode, the ECU controls engine speed at time of vehicle launch based gear position detected by the gear position sensor, road gradient detected by the gradient sensor and engine calibration charts configured in the ECU, whereas in the second mode, the vehicle launch is independent of engine speed.
Typically, the ECU controls engine speed within a pre-determined range based on a first engine calibration chart in case gear selected is first gear, engine speed is less than a predetermined first threshold and gradient is below pre-determined second threshold.
Specifically, in case gear selected is first gear, and either one of engine speed is greater than a pre-determined first threshold and gradient is below pre-determined second threshold, the vehicle launch is independent of engine speed.
Particularly, the ECU locks engine speed to restrain the vehicle launch based on a second engine calibration chart in case gear selected is greater than first gear.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:
FIG. 1 illustrates a flow chart depicting the logic used by a system for controlling engine speed at the time of vehicle launch in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
The foregoing has broadly outlined the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure.
The launching of the vehicle at engaging gear greater than 1st gear and high engine speed can lead to more clutch wear due to increase in clutch temperature, more fuel consumption and vehicle power losses. Further, launching of the vehicle at engaging gear greater than lsl gear and high engine speed can lead to the vehicle getting out of control, thereby causing accidents. Such incidence are more frequent in case of higher bumper to bumper traffic conditions and when the driver is inexperienced. In order to avoid such conditions, the launch of the vehicle is required to be controlled, particularly, the engine speed at the time of vehicle launch is required to be to be controlled. The controlled launch of a vehicle is essential for ensuring safety and enhancing the service life of the clutch and improving fuel economy. To enhance reliability and accuracy of the system for controlling engine speed of the vehicle at the time of vehicle launch, the engine speed is controlled considering specific set of parameters such as vehicle speed, engine speed and gradient at which the vehicle is moving.

Once the vehicle launch/starting procedure has been successfully completed in a controlled manner, full control of the vehicle reverts to the driver. The engine management further takes control of the engine at the time of subsequent vehicle launches.
In accordance with an embodiment of the present disclosure, the engine management system operates in economy mode and a power mode. Referring to Figure 1, in case the user selects economy mode, then automatically fuel efficient calibration charts for all gears are used as is disclosed in the earlier filed Indian Patent application 953/mum/2010 pertaining to subject matter titled "On the fly fuel efficiency control". Further, in case of economy mode, the controlled launch becomes critical. Particularly, the engine speed at the time of launch of the vehicle is to be controlled. In case of user selects power mode, no such restriction of engine being governed by predetermined calibration charts is applicable. Further, in the power mode, the vehicle is launched independent of engine speed in which no logic is applied for controlling engine speed. Hence vehicle can be launched at any engine speed.
Since, already vehicle engine is having supervisory control in economy mode, in such situation, vehicle launch is also very critical. User must control vehicle to have maximum fuel saving during heavy traffic jam conditions as well. "Controlling Engine RPM" during vehicle launch will ensure that vehicle is launched in first gear during launch event. In case vehicle is launched in second or sub sequent higher gears, then ECU will restrict accelerator control (Inside ECU) such that engine RPM will remain at idle RPM or just enough RPM to launch the vehicle on plain roads only. With such configuration, the user is restricted from accelerating the vehicle immediately while the vehicle in launch condition. If vehicle is already running or its speed is more than 3 kmph, then Engine RPM control will be superseded by economy mode calibration.
In accordance with an embodiment of the present disclosure, an engine control system or an engine management system for controlled launch of vehicle and obviating drawbacks of uncontrolled vehicle launch is disclosed. The engine control system controls the engine speed and ensures controlled launch of vehicle based on essential parameters such as gradient of surface on which vehicle is travelling and gear selected. The engine control system controls engine speed at the time of vehicle launch, thereby improving clutch life and fuel economy and at the same time reducing the chances of accidents due

to vehicle getting out of control at the time of launch of the vehicle due to high speed. In accordance with an embodiment of the present disclosure, the engine management system operates in two different modes of engine ECU calibration which are selectable by the user. Typically, the two different modes of ECU calibration are controlled launch mode and user mode. In controlled launched mode
1) ECU is programmed in such a way that if vehicle speed is less than 3 kmph and gradient is less than 0.5°, vehicle will not be launched in 2nd or higher gears as higher engine speed is required for steady launching which will be restricted by ECU logic i.e. engine speed tolerance band for launching is defined and higher engine speed cannot be achieved.
The driver generally launches the vehicle in the 1st gear or greater than 1st gear, the control logic of the engine control system for controlling the engine speed is defined in both cases, and is as under,
a) in case the driver chooses 1st gear while launching, 1st gear engine RPM launching tolerance is feed to the logic in ECU and if the vehicle engine speed meets the condition; than only the vehicle will launch otherwise the logic will lock the engine to its max tolerance limit defined in the ECU. Thus, it will help to launch the vehicle in controlled manner even in 1st gear with steady acceleration.
b) in case the driver chooses a higher gear i.e. >1. In such condition, higher engine speed is required to launch the vehicle which is not in tolerance band of launching the vehicle as per ECU logic. Hence the vehicle is not launched and engine speed will be locked to max tolerance limit.
In the user mode, the vehicle is launched independent of engine speed in which no logic is applied for controlling engine.speed. Hence vehicle can be launched at any engine speed.
Advantages:
The present disclosure provides an engine management system that

• obviates drawbacks of uncontrolled vehicle launch;
• achieves controlled launch of vehicle based on essential parameters such as gradient of surface on which vehicle is travelling and gear selected;
• improves clutch life and fuel economy of the vehicle;
• eliminates the concerns associated with vehicle handled by inexperienced or rash drivers;
• minimizes the engine power losses;
• prevents major fatality during vehicle sudden launch at high engine speed conditions;
• exhibits flexibility to switch between controlled launch mode in which the engine speed at the time of launch of the vehicle is controlled and an user mode in which the vehicle launch is independent of engine speed; and
• is reliable and accurate.

WE CLAIM
1. A system for controlling Engine speed of a vehicle, said system comprising:
• a gear position sensor adapted to sense gear selected by a driver;
• an engine speed sensor adapted to sense engine speed;
• at least one gradient sensor adapted to sense gradient of the surface on which the vehicle is moving;
• at least one mode selection switch adapted to select between a first mode and a second mode;
• an Electronic Control Unit (ECU) adapted receive inputs from said gear position sensor, said engine speed sensor, said gradient sensor and said mode selection switch, wherein in first mode, the ECU is adapted to control engine speed at time of vehicle launch based gear position detected by said gear position sensor, road gradient detected by the gradient sensor and engine calibration charts configured in the ECU, whereas in said second mode, the vehicle launch is independent of engine speed.

2. The system for controlling Engine speed of a vehicle as claimed in claim 1, wherein the ECU is adapted to control engine speed within a pre-determined range based on a first engine calibration chart in case gear selected is first gear, engine speed is less than a pre-determined first threshold and gradient is below pre-determined second threshold.
3. The system for controlling Engine speed of a vehicle as claimed in claim 1, wherein in case gear selected is first gear, and either one of engine speed is greater than a pre-determined first threshold and gradient is below predetermined second threshold, the vehicle launch is independent of engine speed.

4. The system for controlling Engine speed of a vehicle as claimed in claim 1, wherein the ECU is adapted to lock engine speed based on a second engine calibration chart in case gear selected is greater than first gear to restrain the . vehicle launch.