Description:Field of Invention
[001] The invention relates to vehicles provided with internal combustion (IC) engines as prime movers. It more particularly relates to vehicles that are provided with an electronic control unit for controlling the operation of the vehicle’s IC engine and other engine linked components. It additionally relates to such vehicles where exhaust pressure values are required in real time during vehicle operation for ensuring effective functioning of the vehicle’s IC engine and engine-linked components.
Background of the Invention
[002] In modern vehicles, exhaust pressure is crucial for regulating key processes, including but not limited to emission control, turbocharger operation for extra power, and determining when to initiate the regeneration cycle to remove accumulated soot from the exhaust treatment system. Since exhaust pressure sensors operate in demanding environments where heat, soot, and vibrations can adversely impact reading accuracy, ongoing efforts have been to develop methods for determining exhaust pressure that do not rely on these sensors. Enhancing the accuracy of readings derived from such methods has become a focal point of continuous efforts within the industry.
[003] Even in cases where currently available sensors have tended to provide satisfactorily accurate exhaust pressure readings despite the challenging environments in which they are generally employed, their implementation is not deemed economically feasible in all vehicles, except in high-performance vehicles, where users typically accept the higher costs as a suitable trade-off for improved performance. Thus, although these sensors are available, sensor-based solutions for accurately determining exhaust pressure are not universally utilised for economic reasons. Therefore, the objective of the present invention is to provide a method for exhaust pressure determination that is highly accurate yet economical to implement, as it does not require any costly exhaust pressure sensors.
[004] It is another objective of the present invention to provide a method of exhaust pressure determination that is capable of adapting to changing conditions of operation to give accurate exhaust pressure readings in all conditions.
[005] It is still another objective of the present invention to provide a method of exhaust pressure determination that is sufficiently accurate to allow for the use of its readings for effective emissions control.
[006] It is yet another objective of the present invention to provide a method of exhaust pressure determination that is sufficiently accurate to enable effective control of turbocharger operation in a vehicle.
[007] It is another objective of the present invention to provide a method of exhaust pressure determination that is not affected by the adverse conditions existing in the exhaust manifold while determining an accurate value for exhaust pressure.
Summary of the Invention
[008] An embodiment of the invention achieving the stated objective is a method for determining exhaust pressure in a vehicle provided with an internal combustion engine as implemented for a system comprising of a sensor module provided with sensors for determining values of engine speed, torque, exhaust gas recirculation (EGR) flow, airflow, manifold pressure, injection timing, ambient pressure, variable geometry turbo position, and rail pressure, an Engine Management System (EMS) provided with a Model Processing Unit and a calibration module, and a storage unit storing calibration data in the form of a lookup table.
[009] As per the method for determining exhaust pressure in a vehicle provided with an internal combustion engine as a step one, inputs on engine speed, torque, exhaust gas recirculation (EGR) flow, airflow, injection timing, and rail pressure are provided to the Engine Management System (EMS) for processing once the vehicle has been started, to allow EMS to arrive at (P4) intermediate pressure values upon subsequent processing; as a step two, an input on ambient pressure value is introduced from a barometric sensor, forming part of the sensor module, to provide a baseline pressure to allow the Engine Management System (EMS) to convert between a gauge and absolute pressure accurately; as a step three, a value for delta pressure is arrived at by the Engine Management System (EMS) considering the difference between measured manifold pressure and ambient pressure values obtained from the sensor module; as a step four, a value for P4 pressure (intermediate pressure value) is arrived at by combining ambient pressure with delta pressure by the EMS; as a fifth step, a T(u), that is, a lookup table as per calibration data stored in a storage unit, is considered by the EMS for application of a correction factor for the sensed inputs from sensor module on engine speed, engine torque, ambient temperature, air mass flow, and variable geometry turbo position on P4 (the intermediate pressure value); as a sixth step, the EMS calculates a pressure ratio (P Ratio) by combining P4 (the intermediate pressure value) and the correction factor from T(u); the pressure ratio (P Ratio) is crucial for turbocharger control and exhaust gas recirculation management; and as a seventh step, the EMS obtains the final value of the P3 (the exhaust pressure) by combining P4 (the intermediate pressure value) with the pressure ratio (P Ratio).
Brief Description of Drawings
[0010] The accompanying drawings illustrate the present invention, indicating its different features. The description of the present invention would, therefore, be better understood with reference to accompanying diagrams, wherein
[0011] Figure 1 discloses the block diagram of a typical system on which the method in accordance with the present invention is implemented.
[0012] Figure 2 discloses a flow chart representing the step-by-step process of preparation of the data for being feed onto the system’s Electronic Control Unit to enable execution of the method in accordance with the present invention.
[0013] Figure 3 discloses the method in accordance with the present invention as executed in on the system as disclosed in Figure 1.
[0014] Figure 4 discloses a graph showing agreement between sensor pressure values and the modelled values generated upon the execution of the method in accordance with the present invention.
Detailed Description of the Invention
[0015] Referring to the figure 1, the method for determining exhaust pressure in a vehicle provided with an internal combustion engine is implemented by a system comprising of, a sensor module provided with sensors for determining values of engine speed, torque, exhaust gas recirculation (EGR) flow, airflow, manifold pressure, injection timing, ambient pressure, variable geometry turbo position, and rail pressure, an Engine Management System (EMS) provided with a Model Processing Unit and a calibration module, and a storage unit storing calibration data in the form of a lookup table. The disclosed invention is as shown in the diagrams and as described hereinafter.
[0016] Referring to Figure 1, for the system implementing the method as per the disclosed invention, it is stated that the Model Processing Unit of the EMS is linked with the sensor module of the vehicle. The Model Processing Unit of the EMS is also linked with the Calibration Module of the EMS. The Model Processing Unit and the Calibration Module of the EMS are further linked to actuators to control the operation of the turbocharger and exhaust gas recirculation. The turbocharger is connected to the engine exhaust manifold of the internal combustion engine. The engine exhaust manifold of the internal combustion engine is also connected with the intake manifold of the internal combustion engine to allow for exhaust gas recirculation. Actuators linked with the EMS are provided to control the exhaust gas recirculation and turbocharger operation. The turbocharger in this case is typical Variable Geometry Turbocharger (VGT) that can be controlled by the EMS through its linked actuator.
[0017] In the method as per the disclosed invention, referring to Figure 3, it is stated that, as a step one, inputs on engine speed, torque, exhaust gas recirculation (EGR) flow, airflow, injection timing, and rail pressure are provided to the Engine Management System (EMS) for processing once the vehicle has been started, to allow EMS to arrive at (P4) intermediate pressure values upon subsequent processing in the following steps. The Model Processing Unit of the EMS considers the inputs so received from the sensor module.
[0018] In the method as per the disclosed invention, referring to Figure 3, it is stated that, as a step two, an input on ambient pressure value is introduced from a barometric sensor, forming part of the sensor module, to provide a baseline pressure to allow the Engine Management System (EMS) to convert between a gauge and absolute pressure accurately using known mathematical formulas for the same. The ambient pressure is used as further reference, which serves as an input for the calculations to arrive at exhaust pressure (P3) using various calculations, Pratio and pressure drop (Delta P or Delta Pressure) across DPF (Diesel Particulate Filter). The overview of calculations is further shown in logics.
[0019] Referring to Figure 3, it is stated that, in the method as per the disclosed invention, as a step three, a value for delta pressure is arrived at by the Engine Management System (EMS) considering the difference between measured manifold pressure and ambient pressure values obtained from the sensor module. As in step four, the EMS arrives at a value for P4 pressure (intermediate pressure value) by combining ambient pressure with delta pressure. As explained earlier, the exhaust pressure (P3) is calculated by using calculations which use ambient pressure, Pratio and pressure drop (Delta P or Delta Pressure) across the DPF (Diesel Particulate Filter). The delta pressure across the DPF (Diesel Particulate Filter in the exhaust system) is observed because of the soot load inside the DPF. The pressure drop across DPF (Delta P) and SCR (Selective Catalytic Reduction) will be added to ambient pressure to calculate the P4.
[0020] An example is provided below for clarification. 
[0021] Let's assume the Ambient pressure (P6) is 950 mbar. The drop across SCR is 50 mbar. The drop across the DPF is 60 mbar. Then P4 will be a summation of ambient, SCR pressure drop and DPF pressure drop, i.e. 1060 mbar (950+50+60).
[0022] Referring to Figure 3, it is stated that, in the method as per the disclosed invention, as a fifth step, a T(u), that is, a lookup table as per calibration data stored in a storage unit of the EMS, is considered by the EMS for application of a correction factor for the sensed inputs, from sensor module, on engine speed, engine torque, ambient temperature, air mass flow, and variable geometry turbo position on P4 (the intermediate pressure value). As a sixth step, the EMS calculates a pressure ratio (P Ratio) by combining P4 (the intermediate pressure value) and the correction factor from T(u) (as per the calibration data from the data storage). The P4 calculated as shown in the above point is further used to calculate the final exhaust pressure (P3). The pressure ratio = P3/P4. Therefore, the P3 is reversely calculated using multiplying the P Ratio with P4. The pressure ratio (P Ratio) is crucial for turbocharger control and exhaust gas recirculation management.
[0023] Referring to Figure 3, it is stated that, in the method as per the disclosed invention, as a seventh step, the EMS obtains the final value of the P3 (the exhaust pressure) by combining P4 (the intermediate pressure value) with the pressure ratio (P Ratio). EMS executes these steps continuously once the vehicle has been started.
[0024] Referring to Figure 2, it is stated that, in the method as per the disclosed invention, for step five, the lookup table as per the calibration data stored in the storage unit is arrived at through a process involving six steps that are as described hereinafter. As a first step, collection of engine input data on engine speed (N), torque (T), air mass flow (m), variable geometry turbo position, ambient temperature, manifold absolute pressure (MAP), and air-fuel ratio (λ) is done. This data is collected by utilising an experimental setup with sensors for measuring the parameters (N, T, m, variable geometry turbo position, MAP, and λ and others) of an actual internal combustion engine as provided in a typical vehicle along with an actual value for exhaust pressure i.e. P3Sensor to measure it in relation with these sensed values.
[0025] As a second step, calculate a theoretical value for exhaust pressure (P3Model) using a regression approach and the formula, P3Model=a1N + a2T + a3m + … a7λ + Constant, C. As a third step, compare P3Model against actual sensor reading (P3Sensor for actual exhaust pressure readings) and calculate error using the formula, Error = P3Sensor – P3Model.
[0026] As a fourth step, evaluate the metrics Root Mean Square Error (RMSE) and Coefficient of Determination (R2) for P3Model. As a fifth step, adjust values of a1, a2, a3…a7, and C in the formula for P3Model until Root Mean Square Error (RMSE) arrives as close to a minimum and Coefficient of Determination (R2) arrives as close to 1, as experimentally possible. The values Root Mean Square Error (RMSE) and Coefficient of Determination (R2), using P3Model and P3Sensor, being determined as per the formulas

where n is the number of data points
[0027] As a sixth step, then store the values for a1, a2, a3…a7, and C so arrived for different values of P3Model (the modelled exhaust pressure) to form the lookup table as per the calibration data stored in the storage unit. The lookup table so determined is stored as calibration data on the storage unit of the Engine Management System (EMS).
[0028] The matching of the values of P3Model (the modelled exhaust pressure) and P3Sensor (exhaust pressure as per an exhaust pressure sensor) is shown in Figure 4 of the drawings. The level of overlap being exceedingly high, even though the actual vehicle would not have an exhaust pressure sensor, the value of exhaust pressure P3 as determined by the disclosed method would be very closely following the actual value of P3Sensor for any given values of engine speed (N), engine torque (T), air mass flow (m), variable geometry turbocharger (VGT) position, ambient temperature, manifold absolute pressure (MAP) and air fuel ratio (λ) for which calibration table have been prepared and stored in the storage unit of the EMS.
[0029] Technical advantages offered by the invention i.e., method for determining exhaust pressure in a vehicle provided with an internal combustion engine are-
- It is highly accurate yet economical to implement, as it does not require any costly exhaust pressure sensors to be installed on the vehicle for its execution.
- It is capable of adapting to changing conditions of operation to give accurate exhaust pressure readings in all conditions.
- It is sufficiently accurate to allow for the use of its readings for effective emissions control.
- It is sufficiently accurate to enable effective control of turbocharger operation in a vehicle.
- It is not affected by the adverse conditions existing in the exhaust manifold of the internal combustion engine provided on the vehicle while determining an accurate value for exhaust pressure.
[0030] The disclosed invention i.e. the method for determining exhaust pressure in a vehicle provided with an internal combustion engine achieves all the set-out objectives.
[0031] It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the present invention has been herein described in terms of its preferred embodiment, those skilled in the art will recognize that the preferred embodiment herein disclosed, can be practiced with modifications within the scope of the invention herein described. 
, Claims:We Claim,
1. A method for determining exhaust pressure in a vehicle provided with an internal combustion engine as implemented for a system comprising of,
• a sensor module provided with sensors for determining values of engine speed, torque, exhaust gas recirculation (EGR) flow, airflow, manifold pressure, injection timing, ambient pressure, variable geometry turbo position, and rail pressure,
• an Engine Management System (EMS) provided with a Model Processing Unit and a calibration module,
• a storage unit storing calibration data in the form of a lookup table
wherein,
- as a step one, inputs on engine speed, torque, exhaust gas recirculation (EGR) flow, airflow, injection timing, and rail pressure are provided to the Engine Management System (EMS) for processing once the vehicle has been started, to allow EMS to arrive at (P4) intermediate pressure values upon subsequent processing;
- as a step two, an input on ambient pressure value is introduced from a barometric sensor, forming part of the sensor module, to provide a baseline pressure to allow the Engine Management System (EMS) to convert between a gauge and absolute pressure accurately;
- as a step three, a value for delta pressure is arrived at by the Engine Management System (EMS) considering the difference between measured manifold pressure and ambient pressure values obtained from the sensor module;
- as a step four, a value for P4 pressure (intermediate pressure value) is arrived at by combining ambient pressure with delta pressure by the EMS;
- as a fifth step, a T(u), that is, a lookup table as per calibration data stored in a storage unit, is considered by the EMS for application of a correction factor for the sensed inputs from sensor module on engine speed, engine torque, ambient temperature, air mass flow, and variable geometry turbo position on P4 (the intermediate pressure value);
- as a sixth step, the EMS calculates a pressure ratio (P Ratio) by combining P4 (the intermediate pressure value) and the correction factor from T(u); the pressure ratio (P Ratio) is crucial for turbocharger control and exhaust gas recirculation management; and
- as a seventh step, the EMS obtains the final value of the P3 (the exhaust pressure) by combining P4 (the intermediate pressure value) with the pressure ratio (P Ratio).
2. The method for determining exhaust pressure in a vehicle provided with an internal combustion engine as claimed in claim 1, wherein, for step five, the lookup table as per the calibration data stored in the storage unit is arrived at through a process involving the steps,
- collection of engine input data on engine speed (N), torque (T), air mass flow (m), variable geometry turbo position, ambient temperature, manifold absolute pressure (MAP), and air-fuel ratio (λ);
- calculate a theoretical value for exhaust pressure (P3Model) using a regression approach and the formula, P3Model=a1N + a2T + a3m + … a7λ + Constant, C;
- compare P3Model against actual sensor reading (P3Sensor for actual exhaust pressure readings) and calculate error using the formula, Error = P3Sensor – P3Model;
- evaluate the metrics Root Mean Square Error (RMSE) and Coefficient of Determination (R2) for P3Model;
- adjust values of a1, a2, a3…a7, and C in the formula for P3Model until Root Mean Square Error (RMSE) arrives as close to a minimum and Coefficient of Determination (R2) arrives as close to 1, as experimentally possible; and
- then store the values for a1, a2, a3…a7, and C so arrived for different values of P3Model to form the lookup table as per the calibration data stored in the storage unit.
3. The method for determining exhaust pressure in a vehicle provided with an internal combustion engine as claimed in claim 2, wherein the lookup table so determined is stored as calibration data on the storage unit of the Engine Management System.
4. The method for determining exhaust pressure in a vehicle provided with an internal combustion engine as claimed in claim 2, wherein, the values Root Mean Square Error (RMSE) and Coefficient of Determination (R2), using P3Model and P3Sensor, are determined as per the formulas

where n is the number of data points
5. The method for determining exhaust pressure in a vehicle provided with an internal combustion engine, as claimed in claim 1, wherein in the system for implementing said method,
- the Model Processing Unit of the EMS is linked with the sensor module of the vehicle;
- the Model Processing Unit of the EMS is linked with the Calibration Module of the EMS;
- the Model Processing Unit and the Calibration Module of the EMS are further linked to actuators for control of the operation of the turbocharger and exhaust gas recirculation;
- the turbocharger is connected to the engine exhaust manifold of the internal combustion engine;
- the engine exhaust manifold of the internal combustion engine is connected with the intake manifold of the internal combustion engine to allow exhaust gas recirculation; and
- actuators linked with the EMS are provided for controlling the exhaust gas recirculation and turbocharger.
Dated 28th day of February 2025

VIDIT CHOUBEY
(IN P/A 5566)
AGENT FOR THE APPLICANT(S)

To,
The Controller of Patents,
The Patent Office, at Mumbai