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 Novel Device To Improve Vehicle Performance By Engine Speed Restriction
For S.I. Engines
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. Dattatraya R. Katkar, Mr. Deepak S. Kulkarni,
Mr. G. Sathya Narayanan, Mr. N. A. Lende
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 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 restricting vehicle speed vehicles powered with Spark ignited engines. More particularly, it relates to an external air restrictor provided in the air intake system which reduces the air flow quantity and thereby restricting the vehicle speed.
BACKGROUND OF INVENTION:
Rising fuel costs and environmental concerns are two main driving forces advances in automotive and engine technology. Use of alternate fuels such as natural gas, LPG etc. is one of the most cost effective ways to address this problem. Natural gas finds one more application in commercial vehicles which are primarily diesel operated vehicles. The natural gas engines are used in following two ways.
i) Bi-fuel engine
ii) Dedicated natural gas engine. The bi-fuel engines provide an advantage of utilizing existing gasoline engine and extended range and gasoline mode operation as back up in case of emergency . On the other hand, dedicated natural gas engines which are primarily developed for natural gas application provide, improved performance and fuel economy and hence these are getting increasing customer preference.
It is interesting to note that any S.I. engine when operated at speeds beyond max power point and near the fly up speed, following things occur -
i) The engine power drops
ii) Engine speed hunts between max power and fly up speed gives inferior performance.
iii) Vehicle emissions increase
iv) Fuel economy deteriorates
v) Jerks are observed Incidentally, there is no indication to the driver regarding this mode of operation except the jerks. Thus any attempt in the direction avoiding the engine operation in the region between max power point and the fly up point will result in improved engine and vehicle performance from fuel economy and emission point of view.

Considerable amount of work has been done in the past for vehicle speed limiting on electronically controlled fuel injection system in diesel engines,
One prior art teaches about the ECU controlled vehicle speed control system. A vehicle speed control system includes a first electronic control unit for transmitting a difference between actual and target vehicle speeds and control constants that vary depending on the vehicle speed difference when it determines fulfillment of vehicle speed control conditions, and a second electronic control unit for performing the vehicle speed control based on the vehicle speed difference and control constants received through a communication line. Change of the control constants for adjustment of a vehicle speed control function of the system can be easily carried out by changing the control constants stored in the first electronic control unit.
Another prior art teaches about the method and device for controlling vehicle engine. A method and device for controlling the engine of a vehicle comprising an accelerator pedal and an engine speed control circuit comprising in the circuit for closed loop control- of the engine, circuit for interpreting the position of accelerator pedal, which supplies the engine set point to the circuit for closed-loop control of the engine speed depending on the position of the accelerator pedal and in circuit for estimating the external loads on the vehicle and estimating the maximum speed that can be reached by the engine as a function of the external load on the engine.
Another prior art teaches about the vehicular constant-speed control apparatus and method for controlling vehicle speed. If a throttle valve is fully-closed, it is determined whether or not a transmission is to be downshifted, by determining whether or not an acceleration of the vehicle is equal to or greater than a downshift criterion value. The downshift criterion value is set as a value that decreases as the vehicle speed deviation, which is a difference between a vehicle speed and a target vehicle speed, increases. By using a downshift criterion value, an increase in the vehicle speed deviation resulting from a quick downshift on a steep downhill can be restrained. On a gentle downhill, a downshift is not performed even if the vehicle speed deviation assumes a significant value. Thus, it becomes possible to inhibit the vehicle speed from becoming lower than the target vehicle speed during a short period after downshift. Accordingly, an increase in fuel consumption and deterioration of noise of the engine can be restrained.

In yet another prior art one can learn about the engine and vehicle speed control method in direct injection spark ignition engines. A system and method for engine/speed control of a direct injection spark ignition engine include operating the engine in a stratified charge mode and controlling speed based on engine set points for best performance using fuel as a primary torque actuator and airflow as a secondary torque actuator whenever possible to maintain spark at or near MBT. When current operating conditions and/or system constraints prevent use of engine set points corresponding to best performance, speed control becomes the primary objective. Systems and methods according to the present invention improve the compromise between speed control and best performance set-point objectives.
An existing prior art teaches about the engine output control of drive by wire engine. An engine output control method for a vehicle having a drive by wire engine system responsive to a desired engine speed signal. The method comprises the steps of generating a driver demanded engine speed value corresponding to an operator input and generating a speed control system engine speed value corresponding to a predetermined speed value to permit vehicle operation at a constant speed by a speed control system. The method arbitrates between the driver demanded engine speed value and the speed control system engine speed value to derive a first desired engine speed value. This value is limited by a vehicle speed limit value, engine speed limit value, and transmission speed limit value to generate a second desired engine speed value. The engine is then controlled as a function of the second desired engine speed value and an actual engine speed value. In another aspect of the invention, a traction control value and transmission limiting value are generated in the torque domain and arbitrated against the speed domain-based second desired engine speed value to control the engine output.
Another existing prior art speaks about the system and method for torque based vehicle speed control. A system and method for controlling vehicle speed include mutually exclusive closed loop controllers for vehicle speed and acceleration which control vehicle speed by requesting an appropriate wheel torque. The system and method compute, in real time, the wheel torque required to maintain steady vehicle speed or steady acceleration depending on the particular mode of operation. The active closed loop controller acts upon vehicle speed or acceleration errors to output a desired torque request.

It is worthwhile to note at this point that, even though the above mechanisms are used for the vehicle speed control by means of engine speed limiting, incase of mechanical system it becomes complex mechanism and incase of recent system it is easy but the vehicle speed function becomes damped into the ECU. So for providing the driver with flexibility for opting to the vehicle speed function, the current inventions discloses a simple air restrictor which can be connected to the upstream of the intake system for reducing the air flow thereby reduce gas injection quantity for vehicle speed control in the CNG engine powered vehicles.
OBJECT OF THIS INVENTION:
• The main object of this invention is to provide a device to improve the vehicle performance beyond max power point operation.
• Yet another object of the present invention is to provide add - on system to improve the vehicle performance that does not affect the vehicle operation in normal running.
• Yet another object of the present invention is to improve the vehicle emissions and fuel consumption when the engine tends to operate beyond max power point operation.
• Yet another object of the present invention is to provide a device to improve the vehicle performance for engine speeds between max power point to fly up speed that is simple and cost effective.
SUMMARY OF INVENTION:
A novel device to improve vehicle performance by engine speed restriction for S.I. Engines comprising at least one air filter connected to throttle body through the intake hose, said throttle body is mounted on intake manifold, at least one air flow restrictor being mounted upstream of said throttle body to regulate said engine and vehicle performance in region between max power and fly up speed by an auxiliary throttle. The air flow restrictor is an auxiliary throttle body. The auxiliary throttle body is controlled by electronic controller based on inputs. The inputs are engine speed, vehicle speed and position signal of said auxiliary throttle body. The auxiliary throttle body comprises of a throttle plate, housed in

a barrel such that inside diameter of the barrel is equal to or more than the diameter of said throttle plate. The auxiliary throttle is kept in fully open condition during the normal engine running condition. The electrical on off arrangement is attached on top of the auxiliary throttle from outside to actuate said auxiliary throttle when the engine speed exceeds the maximum power point. The throttle plate of the auxiliary throttle is provided with air flow passage of different cross section such as holes of different sections or D section.
BRIEF DESCRIPTION:
Fig. 1 shows the nature S.I. engine at full throttle condition.
Fig. 2 shows the schematic arrangement of air restrictor engine in accordance with the
present invention.
Fig. 3 shows the 3D model of the electrically operated air restrictor
Fig. 4 Cross sectional, Side and Top view of the air restrictor actuated by the throttle plate
with circular holes controlled by electric motor
Fig. 5 shows the cross sectional, side and top view of the air restrictor actuated by the
throttle plate with hemispherical holes controlled by electric motor.
Fig. 6 shows the Functional block diagram of the Speed restricting system.
DETAILED DESCRIPTION OF THE INVENTION:
The present invention aims at providing an air flow restrictor to regulate the engine and vehicle performance in the region between max power and fly up speed. The air flow restriction is achieved by an electrically operated auxiliary throttle. The auxiliary throttle is an orifice plate which operated electrically through an electronic controller based on engine and vehicle speed. During the normal engine and vehicle operation, the auxiliary throttle is kept in the direction of the flow so that it does not cause any restriction to the air flow. The electronic controller operates the auxiliary throttle by 90 deg so that the air entry path is restricted. The sizing of the orifice is done based on engine and vehicle requirements. Once the engine and vehicle speed drops below a certain limit the auxiliary throttle goes back to its normal position.

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.
The sketches showing details of the components of the novel vehicle speed limiting system are given herewith
As shown in fig.l the power curve of typical S.I. engine under FTP condition as a
function of engine speed. The power curve is divided into two parts -
Power curve from lower speed upto maximum power point (1) and the power curve
beyond the maximum power point upto the fly up speed (2). The maximum power point of
engine (3) and the fly up speed (4) are also shown in the diagram.
It is evident from the nature of the power curve that in case of S.I. engines the power is
drops suddenly beyond the Max power point. The operation of the engine in the region
beyond maximum power point (2) forces the engine to reach the fly up speed. This
operation also leads in hunting of the engine operation.
As shown in fig.2, the schematic arrangement of components of air restrictoT in accordance with the present invention comprises of an engine (5) suitably mounted on the vehicle (6) within the vehicle boundaries. The intake system comprises of an air filter (7) connected to the throttle body (8) through the intake hose (9). The throttle body is mounted on the intake manifold (10). The auxiliary throttle (11) is mounted upstream of the throttle body. Opening and closing of the auxiliary throttle is decided by an electronic controller (12) based on the signals received from engine speed sensor (13) and the vehicle speed sensor (14), which is mounted on gear box (15). The fuelling of the engine and the overall operation is controlled through EMS ECU (16) based on signals received from various sensors. The electronic controller (12) can be a separate unit or it can be an integral part of the EMS ECU (16).
As shown in fig.3 the air flow restrictor comprises of a throttle plate (17) which is housed in a barrel (18). The inside diameter of the bane! is equal to or more than the diameter of the main throttle diameter. This ensures that the introduction of the auxiliary throttle does not cause any addition in normal engine operation. During the normal engine, vehicle operation the auxiliary throttle is kept in fully open condition. Electrical on off

arrangement (19) is attached on top of the auxiliary throttle from outside. When the vehicle operation causes the engine speed to exceed the maximum power point, the electronic controller closes the auxiliary throttle. This tends to reduce the air flow and causing the engine power to drop and thus the vehicle achieves a stable operating speed without entering into the fuel cut and hunting mode.
As shown in fig. 4, the throttle plate of the auxiliary throttle is provided with air flow passage of different cross section. This air flow passage ensures that the engine not starve for air in case the auxiliary throttle is closed fully accidentally. The air restrictor is provided in the form of holes (17) or D section (21).
As shown in fig.5, the electronic controller (12) receives the following inputs (22)
i) Engine speed
ii) Vehicle speed
iii) Throttle position signal In addition, the electronic controller is programmed with the following programmable parameters (23) -
i) Engine speed to release the auxiliary throttle
ii) Vehicle speed to release the auxiliary throttle.
iii) Main throttle to auxiliary throttle correlation. Based on these inputs the controller detects a state of engine operation beyond engine maximum power point and the controller then takes following output actions (24) -The controller operates the electrical arrangement on the auxiliary throttle plate, causing the auxiliary throttle plate to close and restricting the engine air flow.. The instantaneous value of throttle position (of main throttle) is used as an initial guess value for auxiliary throttle position. The electronic controller is programmed with a table which gives the position of auxiliary throttle for each corresponding opening of main throttle, which results in equal amount of air flow. Further feedback on auxiliary throttle position is taken from engine speed. The reduction in engine air flow restricts the engine operation in the stoichiometric region. Once the vehicle speed (and thus the engine speed) drops below a certain limit, the electronic controller opens the auxiliary throttle once again. The throttle position sensor signal output is also used as an additional input (if available). The vehicle speed to release auxiliary throttle is vehicle specific and is determined experimentally so as to avoid the jerk.

During the normal engine and vehicle operation the auxiliary throttle is kept fully open and thus it does not affect the normal vehicle operation.
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 novel device to improve vehicle performance by engine speed restriction for S.I.
Engines comprising:
- at least one air filter connected to throttle body through the intake hose,
- said throttle body is mounted on intake manifold,
- at least one air flow restrictor being mounted upstream of said throttle body to regulate said engine and vehicle performance in region between max power and fly up speed by an auxiliary throttle,

2. The novel device to improve vehicle performance by engine speed restriction for S.I. Engines as claimed in claim 1, wherein said air flow restrictor is an auxiliary throttle body.
3. The novel device to improve vehicle performance by engine speed restriction for S.I. Engines as claimed in claim 1, wherein said auxiliary throttle body is controlled by electronic controller based on inputs.
4. The novel device to improve vehicle performance by engine speed restriction for S.I. Engines as claimed in claim 1, wherein said inputs are engine speed, vehicle speed and position signal of throttle body.
5. The novel device to improve vehicle performance by engine speed restriction for S.I. Engines as claimed in claim 1, wherein said auxiliary throttle body comprises of a throttle plate, housed in a barrel such that inside diameter of the barrel is equal to or more than the diameter of said throttle plate.
6. The novel device to improve vehicle performance by engine speed restriction for S.I. Engines as claimed in claim 1, wherein said auxiliary throttle is kept in fully open condition during the normal engine running condition.
7. The novel device to improve vehicle performance by engine speed restriction for S.I. Engines as claimed in claim 1, wherein electrical on off arrangement is attached on top of the auxiliary throttle from outside to actuate said auxiliary throttle when the engine speed exceeds the maximum power point.

8. The novel device to improve vehicle performance by engine speed restriction for S.I. Engines as claimed in claim 5, wherein said throttle plate of the auxiliary throttle is provided with air flow passage of different cross section such as holes of different sections or D section.
9. The novel device to improve vehicle performance by engine speed restriction for S.I. Engines as herein above described and as illustrated in accompanying drawings.