Claims:We claim:
1. An Exhaust Gas Recirculation (EGR) system (100) of a vehicle, said system (100) comprises an EGR path (118) connected between an intake path (110) and an exhaust path (122) of an engine (120) of said vehicle, an EGR valve (114) and an EGR cooler (116) are located in said EGR path (118), and a controller (130) electrically connected to a pressure sensor (104, 112), an engine speed sensor (132) and said EGR valve (114), said controller (130) adapted to
measure an actual pressure of intake air in said intake path (110) through said pressure sensor (104, 112),
measure an engine speed through said engine speed sensor (132),
detect a status of said EGR valve (114), characterized by
determine a reference pressure, based on measured engine speed, detected status of said EGR valve (114), and a correction parameter, and
detect clogging of said EGR cooler (116) based on difference of said actual pressure and said reference pressure.

2. The system (100) as claimed in claim 1, wherein said correction parameter is at least one selected from a group comprising an ambient pressure and an altitude.

3. The system (100) as claimed in claim 1, wherein said status of said EGR valve (114) is obtained by at least one selected from a group comprising air control governor output, a position of said EGR valve (114) and duty cycle of said EGR valve (114).

4. The system (100) as claimed in claim 1, wherein a turbocharger (140) is provided in said exhaust path (122), and wherein a passive wastegate (142) is positioned before said turbocharger (140).

5. A controller (130) to detect clogging in an Exhaust Gas Recirculation (EGR) system (100) of a vehicle, said system (100) comprises an EGR valve (114) and an EGR cooler (116) in an EGR path (118), said controller (130) adapted to
measure an actual pressure of intake air in said intake path (110) through a pressure sensor (104, 112),
measure an engine speed through an engine speed sensor (132),
detect a status of said EGR valve (114), characterized by
determine a reference pressure, based on measured engine speed, detected status of said EGR valve (114), and a correction parameter, and
detect clogging of said EGR cooler (116) based on difference of said actual pressure and said reference pressure.

6. The controller (130) as claimed in claim 5, wherein said correction parameter is at least one selected from a group comprising an ambient pressure and an altitude.

7. The controller (130) as claimed in claim 5, wherein said status of said EGR valve (114) is obtained by at least one selected from a group comprising air control governor output, a position of said EGR valve (114) and duty cycle of said EGR valve (114).

8. A method for detecting clogging in an Exhaust Gas Recirculation (EGR) system (100), said method comprising the steps of:
measuring an actual pressure of intake air in said intake path (110) through a pressure sensor (104, 112);
measuring an engine speed through an engine speed sensor (132);
detecting a status of an EGR valve (114), characterized by
determining a reference pressure value, based on said engine speed, said status of said EGR valve (114), and a correction parameter, and
detecting clogging of an EGR cooler (116) based on difference between said actual pressure and said reference pressure.

9. The method as claimed in claim 6, wherein said correction parameter is at least one selected from a group comprising an ambient pressure and an altitude.

10. The method as claimed in claim 6, wherein said step of detecting status of said EGR valve (114) is obtained by at least one selected from a group comprising air control governor output, a position of said EGR valve (114) and duty cycle of said EGR valve (114).
, Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed:

Field of the invention:
[0001] The present invention relates to a controller and a method of determining clogging in an exhaust gas recirculation (EGR) system.

Background of the invention:
[0002] Cooling of the recirculated exhaust gas helps in reduction of NOx emissions from diesel engines. Partial clogging or complete blockage/clogging of the EGR cooler results in reduced efficiency and increase in temperature of EGR entering the engine cylinders, which impacts on the engine out emissions. To ensure acceptable engine out emissions, it is prudent to continuously monitor the clogging of EGR cooler and notify the user to clean or replace the EGR cooler in case of clogging. In vehicles with passive wastegate turbochargers, any gas not passing through the EGR line will have to pass across the turbine. This results in a higher boost pressure value for the same engine operating condition.

[0003] According to a prior art JP2013151868, a blocking detection method and device of EGR cooler is disclosed. A temperature difference between an intake air temperature in an intake manifold in a state that an EGR valve is opened and an intake air temperature in an intake manifold in a state that the EGR valve is closed, is obtained at the maintenance of idling operation after the warm-up of a diesel engine. When the temperature difference is not more than a threshold value set in advance, an EGR cooler is determined to be blocked.

Brief description of the accompanying drawings:
[0004] An embodiment of the disclosure is described with reference to the following accompanying drawing,
[0005] Fig. 1 illustrates an Exhaust Gas Recirculation (EGR) system of a vehicle, according to an embodiment of the present invention, and
[0006] Fig. 2 illustrates a method of detecting clogging of the EGR system, according to the present invention.

Detailed description of the embodiments:
[0007] Fig. 1 illustrates an Exhaust Gas Recirculation (EGR) system of a vehicle, according to an embodiment of the present invention. The system 100 comprises an EGR path 118 connected between an intake path 110 and an exhaust path 122 of an engine 120 of the vehicle (not shown). An EGR valve 114 and an EGR cooler 116 are located in the EGR path 118. The vehicle comprises a turbocharger 140, having a turbine 124 in the exhaust path 122 and a compressor 106 in the intake path 110. The turbine 124 and the compressor 106 are connected to each other through a shaft. Further, in the intake path 110, an air filter 102 is provided at the beginning, followed by a compressor 106. An air cooler 108 is provided downstream of the compressor 106, and a pressure based Mass Flow (MF) sensor 104 is provided downstream of the air cooler 108. An optional Manifold Air Pressure (MAP) sensor 112 is usable if the MF sensor 104 is unavailable. In the exhaust path 122, a Diesel Particulate Filter (DPF) 126 and a Selective Catalytic Reduction (SCR) catalyst 128 are provided. A bypass path 144 for the turbocharger 140 is also provided having a wastegate 142. The DPF 126 and the SCR catalyst 128 are provided for emission reduction. The various components of the vehicle are provided for general layout and must not be limited to the same. Other parts/components or may be added or removed from the vehicle layout without departing from the scope of the invention. A first arrow 136 shows the flow direction of the intake air and the second arrow 138 shows the flow direction of the exhaust gases.

[0008] The system 100 further comprises a controller 130 electrically connected to the pressure sensor, i.e. either MAP sensor 112 or the MF sensor 104 based on the availability, an engine speed sensor 132 and the EGR valve 114. The controller 130 is adapted to measure an actual pressure of intake air in the intake path 110 through the pressure sensor 104, 112, measure an engine speed through the engine speed sensor 132 and detect a status of the EGR valve 114. The status of the EGR valve 114 being percentage of opening such as 10%, 20%, 45% and the like. The system 100 is characterized by, the controller 130 adapted to determine a reference pressure, based on measured engine speed, detected status of the EGR valve 114, and a correction parameter, and detect clogging of the EGR cooler 116 based on difference of the actual pressure and the reference pressure.

[0009] The controller 130 checks the difference with a threshold limit and accordingly detects the clogging if the limit is crossed.

[0010] A map provides the calibrated pressure based on different combination of engine speed and the status of the EGR valve 114. The map is stored in the memory element 134 of the controller 130. The correction parameter is any one selected from a group comprising an ambient/environment pressure and an altitude. Based on the value of the ambient pressure or altitude or both, at the current location of the vehicle, the controller 130 applies the correction parameter to the calibrated pressure to determine the reference pressure. The value of the correction parameter is obtained through respective sensors known in the art or are received through a server based on the vehicle position.

[0011] Further, the status of the EGR valve 114 is obtained by at least one selected from a group comprising air control governor output, a position of the EGR valve 114 and duty cycle of the EGR valve 114.

[0012] The controller 130 triggers an alert for notification through at least one of an audio, visual and haptic means upon detection of clogging of the EGR cooler 116.

[0013] A working of the present invention is explained with an example of diesel engine 120. In the diesel engine 120 with turbocharger 140, a passive wastegate 142 is provided. The exhaust gas 138 from the engine 120 has only two paths to escape as long as the wastegate 142 remains closed, one through the EGR path 118 having the EGR cooler 116, and the other through the turbine 124 of the turbocharger 140. In case of blockage of the EGR cooler 116, the exhaust gas has only one path left, i.e. through the turbine 124 of the turbocharger 140. The excess exhaust gas or exhaust energy flowing through the turbine 124 results in increased boost pressure or the actual pressure in the intake path 110. The increase in the actual pressure is compared with reference pressure to detect the clogging of the EGR cooler 116.

[0014] In accordance to an embodiment of the present invention, the controller 130 to detect clogging in the Exhaust Gas Recirculation (EGR) system 100 of a vehicle is provided. The system 100 comprises the EGR valve 114 and the EGR cooler 116 in the EGR path 118. The controller 130 adapted to measure the actual pressure of intake air in the intake path 110 through the pressure sensor 104, 112, measure the engine speed through the engine speed sensor 132 and detect the status of the EGR valve 114. The controller 130, characterized by, is further adapted to determine the reference pressure, based on measured engine speed, detected status of the EGR valve 114, and the correction parameter, and detect clogging of the EGR cooler 116 based on the difference of the actual pressure and the reference pressure.

[0015] The correction parameter is at least one selected from a group comprising an ambient pressure and an altitude. The ambient pressure is measured through a Pressuresensor or received through the server. Alternatively, the altitude is detected through satellite positioning systems, which is used in revising the reference pressure. The altitude is correlated to the ambient pressure.

[0016] The status of the EGR valve 114 is obtained by at least one selected from a group comprising air control governor output, a position of the EGR valve 114 and duty cycle of the EGR valve 114.

[0017] The controller 130 does not process the signals if the wastegate 142 opens due to excessive pressure. The maximum boost pressure value until which the wastegate 142 is not opened is known beforehand, which depends on the stiffness of a spring of the wastegate 142, and is calibrated as a threshold pressure. The controller 130 activates the detection of clogging only if the actual pressure is less than the calibrated threshold pressure value. Otherwise the controller 130 does not initiate the block or clogging detection of the EGR cooler 116.

[0018] Fig. 2 illustrates a method for detecting clogging of EGR system, according to the present invention. The method comprises plurality of steps. A step 202 comprises measuring the actual pressure of intake air in the intake path 110 through the pressure sensor 104, 112. The actual pressure value (or boost pressure) is selected either from the pressure signal from MF sensor 104 or from the MAP sensor 112. A step 204 comprises measuring the engine speed through the engine speed sensor 132. A step 206 comprises detecting the status of the EGR valve 114. The method is characterized by a step 208 which comprises determining a reference pressure value, based on the engine speed, the status of the EGR valve 114, and the correction parameter, and a step 210 which comprises detecting clogging of the EGR cooler 116 based on difference between the actual pressure and the reference pressure. The actual pressure and the reference pressure are compared and a deviation is calculated. The deviation is compared with a calibrated threshold value. The threshold value is calibrated considering the variation from different turbocharger samples (min, mean and max). If the deviation is higher than the calibrated threshold value then the status for EGR cooler 116 or clogging is detected. The step 206 of detecting status of said EGR valve 114 is obtained by at least one selected from a group comprising air control governor output, a position of the EGR valve 114 and duty cycle of the EGR valve 114.

[0019] The correction parameter is at least one selected from a group comprising an ambient pressure and an altitude. The map stores calibrated pressure values based on the engine speed and the status of the EGR valve 114. The actual pressure values obtained after complete maturity in performance and emission calibration (such in engine/chassis dynamometer) is mapped/stored in the map based on engine speed and EGR position. The output of the map is corrected based on correction parameter and the corrected output is considered as the reference pressure.

[0020] According to an embodiment of the present invention, the controller 130 is provided to detect partial clogging or complete blocking of EGR cooler 116 of engines 120 with turbochargers 140 having passive wastegate 142 without having to install any specific temperature sensors. If a reference pressure is mapped based on engine speed and position of the EGR valve 114, and thresholds for pressure deviations are defined, then the partial clogging or complete blockage of EGR cooler 116 is detectable. Any errors are notified without having a temperature sensor and independent of other monitoring functions like air mass deviation monitoring.

[0021] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.