FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13) TITLE OF THE INVENTION
Novel EGR Controller for Internal Combustion Engine
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. Vishwas Vaidya, Mr. Dattatraya Katkar Ms Vrishali Nawle, Mr. G Sathyanarayanan, Mt. Deepak Kulkarni, Mr. Arvind Singh 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 describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION:
The disclosure relates to emission control device for engines. More particularly, it relates to EGR controller for Engines. Further, it refers to a standalone EGR controller to engines with mechanical fuel injection system.
BACKGROUND OF THE INVENTION:
Stricter emission norms and environmental friendliness of vehicles are driving forces for development in engine emission technology. In order to address these challenges, various technologies have emerged out. Exhaust gas recirculation is one such a technology that is used as a NOx control strategy. In case of electronically fueled engines EGR control is as a part of built in Engine management system. In this case the cooled (optional) EGR is supplied to the engine which results in substantial reduction of NOx. The EGR supply to the Engine is controlled through the EGR valve which is operated through EGR controller. The EGR controller is a sub part of the Engine management system. In addition, various inputs regarding engine speed, load, coolant temperature, and vehicle speed etc are through base engine management system,
If, similar technology is transferred to mechanically fueled engines, it would result in similar results. The present disclosure aims at development of a standalone EGR controller for mechanically fuelled engines. The EGR controller is capable of receiving inputs from add on sensors and regulating the EGR flow into the engine. In addition, the controller has various EGR regulating & cut off strategies, built in diagnostics etc. The diagnostic feature enables vehicle operator to get an intimation of EGR system malfunction and tack corrective actions.
PRIOR ART:
US Patent 416 4206 teaches about a closed loop programmable EGR control system is disclosed. The EGR control system comprises a first read only memory having a look up table of base EGR pulse widths as a function of engine speed and absolute manifold pressure. The base EGR pulse width is corrected to a total desired pulse width by adding a

correction pulse width obtained from a second read only memory. The second ROM stores values of the correction pulse width in a look up table as a function of engine speed and engine coolant temperature. This desired value of EGR pulse width is then compared to the actual EGR flow as sensed directly by a differential pressure transducer located in the exhaust gas recirculation conduit and an error signal is generated there from. The error signal is subsequently used to operate a solenoid pilot valve that alternately applies either a vacuum or atmospheric vent at a controllable rate to an EGR valve regulating the amount of exhaust gas recirculated to thereby reduce the error between the actual and desired EGR values
US Patent 6732723B2 explains about a method and system for controlling EGR rats of an internal combustion engine includes measuring a mass airflow passing to the intake throttle and a desired mass airflow. An error signal is produced representative of a difference between the measured mass airflow and the desired mass airflow. A pair of control signals is produced in response to such produced error signal. One of the pair of control signals is used to adjust that intake throttle to control mass airflow through such intake throttle. The other one of the pair of control signals is used to adjust EGR flow through the EGR valve. The pair of control signals operates the intake throttle and the EGR valve to drive the error signal to a null. In one embodiment, one of the control signals used to adjust the EGR valve is used to provide such adjustment only when the intake throttle is in a position to provide substantially maximum mass airflow through such intake throttle to the intake of the engine. In another embodiment, the pair of control signals operates to drive the throttle to a close position only when such error signal is unable to be driven towards the null solely from adjustment by the EGR valve.
US Patent 6305167 Bl A method of controlling an internal combustion engine includes determining an exhaust gas recirculation (EGR) command signal based on at lease one engine condition, and determining a variable geometry turbocharger (VGT) command signal based on at least one engine condition and at least partially based on the EGR

command signal. Advantageously the EGR system and VGT system may be continuously and simultaneously controlled, taking into account the effects of each system on the other, to provide improved and more precise control over engine air flow. In an alternative embodiment, an engine may be controlled with a feedback control system where engine intake chemical composition is the feedback variable.
The first patent calculates the EGR flow through look up tables based on engine speed & manifold absolute pressure which is further corrected based on engine coolant temperature sensor . The corrected pulse width is then checked against the actual EGR flow sensor located in the EGR circuit Thus, it makes use of only to variables to estimate the EGR quantity, which is further corrected using other variables. The second patent makes engine air flow rate to calculate the EGR quantity. This signal is available only in engines having electronic fuel metering. The third patent makes use of position of VGT position signal, chemical composition of intake air to determine the quantity of EGR
Thus, all the above mentioned patents make use of more number of sensors and feedback signal to determine and correct the EGR quantity. At times these sensors may not be available on all the engines. Thus the system may remain engine specific. The aim of the present disclosure is to provide an EGR system that makes use of minimum sensors which are necessarily available on all the engines. The EGR quantity determination is dependent on direct engine parameters such as engine speed & load and the correction is from the position feedback of the valve.
OBJECT OF THIS INVENTION:
• The main object of this disclosure is to obviate above mentioned drawbacks.
• Another object of the disclosure to provide an exhaust gas recirculation controller (EGR) that can be incorporated to mechanically fuelled engines with add on sensors.
• Yet another object of this disclosure is to provide an EGR controller that is of stand alone type.

• Yet another object of this disclosure is to provide an EGR controller that has a
diagnostic provision for ease of fault detection.
• Yet another object of this disclosure is to provide an EGR controller that is
programmable and various input parameters can be customized to suit various
applications.
• Yet another object of this discJosure is to provide an EGR controller that that has built in strategies which protect the engine during extreme operating conditions.
• Yet another object of this disclosure is to provide an EGR controller that can be fitted on in-use vehicles.
SUMMARY OF INVENTION:
Novel EGR Controller for Internal Combustion Engine comprising:
- a mechanically fuelled Internal Combustion Engine coupled with an Exhaust Gas Recirculation (EGR) controller
- said EGR controller has a EGR valve operated through vacuum generated by a vacuum pump and controlled through a vacuum modulator,
- said vacuum pump is mounted on an alternator which is driven by said engine,
- duty cycle of said vacuum modulator is controlled through said EGR controller according to signals received from sensors mounted on said engine,
- said engine is fuelled by a Fuel Injection Pump (FIP) coupled to a potentiometer.
BRIEF DESCRIPTION:
The sketches showing details of the arrangement for novel EGR controller for Internal
Combustion Engine are given herewith
Figure 1 shows the schematic connections for the EGR control of an engine
Figure 2 shows the input & output block diagram for the Novel EGR controller in
accordance with the present disclosure.
Fig 3 shows the flow chart for finalizing the EGR valve lift based on various inputs for
normal operation.

Fig. 4 shows the schematic details of the map programmed into the EGR controller. Fig 5 shows the flow chart to determine the EGR valve lift during idling condition.
DESCRIPTION OF PREFFERED EMBODIMENTS:
The present disclosure aims at providing an EGR controller for internal combustion engines which is of stand alone type. The functionality of the EGR controller is based on minimum input signals from variety of different sensors. The controller detects the state of operation of the engine and based on this determines the EGR valve lift required for optimum operation. Different maps are programmed into the EGR controller for different engine operating stares. The controller also compares the actual valve opening with respect to calculated valve lift based on the feedback signal received from EGR valve position. In addition, the controller is also programmed with strategies which protect the engine during abnormal operating conditions encountered in extreme conditions. Further, the controller also provides on board diagnostic (OBD I) in case of system malfunction and activates the limp home strategies.
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the disclosure only, and not for the purpose of limiting the same.
As shown in figure 1, the schematic of connections for the EGR control at engine level comprises of an IDr engine (II) having following components that are important from EGR point of view-
i) EGR controller (12)
ii) EGR valve (13)
iii) vacuum modulator (14).
iv) alternator (15)with vacuum pump (16)
v) fuel injection pump (17) with a potentiometer (18) The EGR valve is (13) is vacuum operated and its opening is controlled through vacuum modulator (14). The vacuum required for EGR valve is generated through the vacuum

pump (16) which is mounted on the alternator (15) and driven by the engine (11). The duty cycle of vacuum modulator is controlled through the EGR controller (12). The EGR controller in turn receives signals from various sensors mounted on the engine. Two such important sensor signals are engine speed received from alternator & throttle position signal received from potentiometer (18). The potentiometer is mounted on the FIP lever which is operated by the accelerator cable which is a three pin (pin 1, 2,3) electronic device for which resistance between pin 1 and 3 is constant and resistance between pin 2 and 3 is variable (but always equal to or less than the resistance between pin 1 and 3) depending on the throttle pedal position. When the Driver presses the Throttle pedal the resistance between pin 2 and 3 increases and the voltage sensed by the EGR controller also increases and vice versa. This change in throttle pedal position in turn causes change in resistance which in turn causes change in voltage which act as a input for EGR controller to detect the throttle pedal position.
As shown in fig.2, the electronic EGR controller (12) is a microprocessor based unit capable of receiving multiple inputs (21). The EGR controller receives following inputs -
i) Engine coolant temperature
ii) Engine speed
iii) Vehicle speed
iv) Throttle position
v) Absolute pressure sensor
vi) EGR position feedback In addition the controller is configured with various parameters (22) in terms of maps and set points. The configured parameters are -
i) MAPs
ii) Coolant temperature upper & lower set points
iii) Barometric pressure set points Based on the various inputs received and the configured parameters, the EGR controller decided following output actions (23) -
i) EGR valve lift
ii) Malfunction Indication Lamp activation

The derived valve lift is checked with actual valve lift through feedback signal (24) received from the potentiometer on EGR valve and necessary corrective actions are taken to match actual EGR valve lift with the calculated valve lift. In addition, the controller provided diagnostic (25) on K line which is a single wire communication based on Keyword 2000 protocol (KWP2000)
Fig. 3 shows the Schematic flow chart for the operation of the EGR controller. As shown in the diagram, the controller (12) receives the inputs (21). Based on the inputs received the controller firstly determines whether any of the EGR cut off condition (31) is present. The EGR cut off conditions include -
i) Malfunction of the sensor signal as for example Coolant temperature sensor
disconnection, Potentiometer disconnection etc. When coolant sensor is
disconnected from EGR controller the voltage signal level received by the EGR
controller is high which is not within the operating range of the Coolant
Temperature Sensor, we detect this condition as malfunction and SET the
Malfunction Indicator Lamp. In this condition when this faul is detected the
EGR is cut off as this is the safe operating condition for engine and after
treatment, as the EGR controller does not have the correct coolant information
for proper working.
ii) Barometric pressure lower than set point
iii) Engine in idling condition for more than specified time.
If so. the EGR supply to the engine is cut off. In absence such EGR cut condition, EGR
controller proceeds further to determine the engine state (acceleration or steady state) based
on the acceleration set value (threshold) (32). If the engine is in acceleration mode, the
controller determines the EGR valve lift based on acceleration map. If the engine is in
steady state, the controller, further checks the engine coolant temperature (33). If the
engine coolant temperature is lower than the minimum set value or higher than the
maximum set value, the controller determines the EGR valve lift based on the coolant
temperature map. If none of the above conditions are satisfied the EGR controller
determines the EGR valve lift based on the main map (34).

As shown in fig. 4, the EGR map comprises of a matrix (41). The matrix has engine speed on X axis (42)and the throttle signal (43) on Y axis. The desired EGR valve opening is specified in the map. EGR valve lift (44) is specified in the map cells as a function of engine speed & throttle position. The structure of different map remains the same however; the values of EGR valve lift vary. The EGR valve lift provides a feedback signal which in turn is used to correct the error in actual & desired valve lift. As shown in fig. 5 the flow chart for excess idle EGR cut off strategy comprises of comparing the engine speed with the idle zone value (51) which is programmed into the controller. If the engine speed is lower than the idle zone, the controller measures the time (52) for which the engine remains in idle mode. If the engine idle mode continues for a time more than idling timer threshold, the controller cuts off the EGR to protect the engine considering it as an abnormal condition. However, before the idling timer threshold, if the engine speed exceeds the idle exit zone value (53), the counter is reset and the EGR valve lift based on engine state and condition is determined. For this engine the engine RPM input is taken from the W terminal from the alternator, unlike other engines in which the RPM input is taken from Crank Angle Sensor. .Details provided in description of fig. 4.
This figure is a look up table(41) (with indices as throttle(43) and engine RPM(42)), which contains EGR valve lift values for different combination of control input parameters
1. Coolant
2. Rpm
3. Throttle
4. Rate of change of Throttle
Depending upon the values for above parameters the EGR Controller decides the % PWM duty cycle(44) value using the Look Up table(41) (fig. 4) thus reducing the NOx generation and controlling the emission of the vehicle. Higher the value of PWM duty cycle(44) more is the opening of the EGR valve and less is the NOx generated by the vehicle.

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. Novel EGR Controller for Internal Combustion Engine comprising:
- a mechanically fuelled Internal Combustion Engine coupled with an Exhaust Gas Recirculation (EGR) controller
- said EGR controller has a EGR valve operated through vacuum generated by a vacuum pump and controlled through a vacuum modulator,
- said vacuum pump is mounted on an alternator which is driven by said engine.
- duty cycle of said vacuum modulator is controlled through said EGR controller according to signals received from sensors mounted on said engine.
- said engine is fuelled by a Fuel Injection Pump (FIP) coupled to a potentiometer.

2. The system as claimed in claim 1 wherein said EGR controller is a electronic one based on microprocessor receiving multiple inputs such as Engine coolant temperature. Engine speed, Vehicle speed, Throttle position, Absolute pressure sensor, EGR position feedback.
3. The system as claimed in claim 1 wherein one sensor receives signal of said engine speed from W terminal of said alternator and another sensor receives signal of said throttle position from said potentiometer.
4. The system as claimed in claim 1 wherein said EGR controller is configured with various parameters such as maps. Coolant temperature upper and lower set points, barometric pressure set points.
5. The system as claimed in claim 1 wherein said EGR controller controls EGR valve lift,
activation of malfunction indication lamp based on inputs received and configured
parameters.
6. The system as claimed in claim 1 wherein said valve lift is checked with actual valve lift
through feedback signal received from said potentiometer to take necessary corrective
actions.

7. The system as claimed in claim 1 wherein said EGR controller is provided with a diagnostic on K line, which is a single wire communication based on Keyword 2000 protocol.
8. The system as claimed in claim 1 wherein said EGR is cut off when malfunction of the sensor signal occurs or barometric pressure is less than set point or said engine is in idle condition for more than specified time.
9. A method of controlling exhaust gas recirculation in a mechanically fuelled Internal Combustion engines comprising acts of:
basing functionality of said EGR controller on minimum input signals from variety of different sensors,
detecting state of operation of said engine by said controller and based on which requirement of EGR valve lift is determined for optimum operation,
configuring different maps into said EGR controller for different engine operating stares,
comparing actual valve opening with respect to calculated valve lift based on the feedback signal received from EGR valve position,
configuring strategies into the controller to protect said engine during abnormal operating conditions encountered in extreme conditions,
providing on board diagnostic in case of system malfunction and activate limp home strategies.
10. The method as claimed in claim 9 wherein when throttle pedal is pressed the resistance between pin 2 and 3 increases and voltage sensed by said EGR controller also increases and vice versa.
11. The method as claimed in claim 10 wherein change in said voltage acts as an input for EGR controller to detect the throttle pedal position.

12. The method as claimed in claim 9 wherein excess idle EGR cut off strategy comprises of acts of comparing the engine speed with the idle zone value which is configured into said controller and if the engine speed is lower than the idle zone, the controller measures time for which the engine remains in idle mode, and if the engine idle mode continues for a time more than idling timer threshold, the controller cuts off the EGR to protect the engine considering it as an abnormal condition and if before idling timer threshold, if engine speed exceeds the idle exit zone value, counter is reset and the EGR valve lift based on engine state and condition is determined.
13. The method as claimed in claim 9 wherein in absence EGR cut condition, EGR controller proceeds furrther to determine the engine state (acceleration or steady state) based on the acceleration set value and if said engine is in acceleration mode, said controller determines the EGR valve lift based on acceleration map, and if the engine is in steady state, the controller, further checks the engine coolant temperature and if the engine coolant temperature is lower than minimum set value or higher than the maximum set value, the controller determines the EGR valve lift based on the coolant temperature map and if none of the above conditions are satisfied said EGR controller determines the EGR valve lift based on main map (34),
14. Novel EGR Controller for Internal Combustion Engine and method of controlling the same substantially as hereinabove described with reference to the accompanying drawings.