Claims:We Claim:
1. A system (10) to detect malfunctioning of an exhaust gas recirculation (EGR) cooler (12) in an exhaust gas recirculation system (14), said system comprising :
- a temperature sensor (16) adapted to detect a manifold temperature in said EGR system (14);
- a control unit (18) connected to said temperature sensor (16);
characterized in said system :
said temperature sensor (16) is positioned downstream to an EGR valve (17);
said control unit (18) detects malfunctioning of said EGR cooler (12) based on a signal received from said temperature sensor (16).

2. The system (10) as claimed in claim 1, wherein said temperature sensor (16) is positioned upstream to an inlet manifold (20) of an engine.
3. The system (10) as claimed in claim 1, wherein said malfunction in said EGR cooler (12) is detected when said received temperature is more than a predefined threshold value.
4. The system (10) as claimed in claim 1, wherein said detected manifold temperature is a temperature of a recirculated exhaust gas mixed with an ambient air in said inlet manifold (20).
5. The system (100 as claimed in claim 1, wherein said control unit (18) is an engine electronic control unit.

6. A method of determining malfunction of a EGR cooler (12) in an EGR system (14), said EGR system (14) comprising, a temperature sensor (16) located along the an inlet manifold (20) and downstream to said EGR cooler (12), said method comprising:

- receiving, a manifold temperature of air and exhaust by said temperature sensor (16) ;

- comparing said received manifold temperature with a predefined threshold temperature of said air and said exhaust , by a control unit (18); and

- determining, by said control unit (18), a malfunction of said EGR cooler (12) if said received manifold temperature is greater than said predefined threshold temperature.

, 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] This invention relates to the field of detecting malfunctioning of an exhaust gas recirculation (EGR) cooler in an EGR system.

Background of the invention
[0002] Exhaust gas recirculation (EGR) is a NOx emission control technique applicable to a wide range of diesel engines from light, medium and heavy-duty diesel engines right up to two-stroke low-speed marine engines. The configuration of an EGR system depends on the required EGR rate and other demands of the particular application. The EGR cooler is a component used to lower the temperature of the exhaust gases that are recirculated by the EGR system. The EGR system recirculates exhaust gases back into the engine in order to decrease cylinder temperatures and NOx emissions. The gas circulated by the EGR system can be considerably hot, especially in vehicles equipped with diesel engines. For this reason, many diesel engines are equipped with EGR coolers to lower the temperature of the exhaust gases before they enter the engine.

[0003] Prior art patent application US6848434 discloses a system is disclosed for diagnosing operation of an EGR cooler disposed in-line with an EGR conduit fluidly coupled between an intake manifold and an exhaust manifold of the engine such that exhaust gas flowing through the EGR conduit also flows through the EGR cooler. Means are provided for determining a temperature of exhaust gas produced by the engine, a temperature of exhaust gas exiting the EGR cooler. A control computer is configured to diagnose operation the EGR cooler as a function of the temperature of exhaust gas produced by the engine, the EGR cooler outlet temperature, the engine coolant temperature and the EGR flow rate.
Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

[0005] FIG. 1 illustrates an exhaust gas recirculation (EGR) system in a vehicle in accordance to one embodiment of the invention; and

FIG.2 illustrates a flowchart of a flowchart of a method of determining of determining malfunction of an EGR cooler in the EGR system.

Detailed description of the embodiments
[0006] FIG. 1 illustrates a system to detect malfunctioning of an exhaust gas recirculation (EGR) cooler in an exhaust gas recirculation system 14 in accordance with one embodiment of the invention. The system 10 comprises a temperature sensor 16 adapted to detect a manifold temperature in the EGR system 14. The system 10 comprises a control unit 18 connected to the temperature sensor 16. The temperature sensor 16 is positioned downstream to an EGR valve 17. The control unit 18 detects malfunctioning of the EGR cooler 12 based on a signal received from the temperature sensor 16.

[0007] The working of the EGR system 14 will be explained in further detail. The exhaust gas recirculation is a method by which a portion of an engine’s exhaust gas is returned to its combustion chamber via an inlet manifold. The EGR system 14 comprises the EGR valve 17, the EGR cooler 12 and the exhaust manifold 22. The exhaust gas from the exhaust manifold 22 enters the EGR cooler 12 where the exhaust gas is cooled down and is mixed with the air in the inlet manifold 20. The temperature sensor 16 is positioned upstream to the inlet manifold 20. The control unit 18 is chosen from a group of control units comprising a microcontroller, a microprocessor or an IC chip or the like. According to one embodiment of the invention, the control unit 18 is an engine electronic control unit. However, the control unit 18 is not restricted to the above disclosed, but can be any electronic control unit 18 in the vehicle that is connected to the temperature sensor 16. The manifold temperature detected by the temperature sensor 16 is the temperature of the exhaust gas, which got mixed with the inlet air that is directed from the inlet manifold 20. The amount of the inlet air entering the inlet manifold 20 is based on the percentage of an accelerator pedal pressed by a user of the vehicle.

Figure 2 illustrates a flowchart of a method for determining malfunction of an EGR cooler 12 in an EGR system 14. The EGR system 14 comprises a temperature sensor 16 located in an inlet manifold 20 and downstream to the EGR cooler 12. In step S1, the temperature sensor 16 detects a manifold temperature of air and exhaust. In step S2, the received manifold temperature is compared with a predefined threshold temperature of the air and the exhaust, by a control unit 18. In step S3, the control unit 18 detects a malfunction in the EGR cooler 12, when the received manifold temperature is greater than the predefined threshold temperature.

The EGR system 14 recirculates exhaust gases back into the engine in order to decrease cylinder temperatures and NOx emissions. The exhaust gas from the exhaust manifold 22 is redirected to the EGR cooler 12 to reduce the temperature of the exhaust gas. The EGR cooler 12 reduces the temperature of the exhaust gas (for instance, from a 700 degree Celsius to 175 degree Celsius). The EGR cooler 12 comprises thin passages and fins to cool the exhaust gas before entering an engine cylinder 24. The cooled exhaust gas gets mixed with the inlet air and enters the engine cylinder 24. The temperature sensor 16 present after this mixing point detects the temperature of the exhaust gas and the inlet air mixture. The temperature sensor 16 detects the temperature for a predefined time interval. The control unit 18 receives the signal from the temperature sensor 12 and compares the received temperature with a predefined threshold value. When the received temperature is more than the predefined threshold value, then the control unit 18 detects a malfunction in the EGR cooler 12. The control unit 18 alerts the user of the vehicle regarding the malfunction of the EGR cooler 12 when the received temperature is more than the predefined threshold value.

With the above-disclosed system, an additional temperature sensor at the EGR valve 17 to detect the temperature of the exhaust gas is avoided, thus providing a low cost solution. The temperature sensor 12, which is used to detect the temperature of the inlet air previously, is shifted to a position after the mixing portion (where the exhaust gas gets mix with the inlet air) in the inlet manifold 20 to detect the temperature of the exhaust gas, thus detecting a malfunction in the EGR cooler 12 as shown in the figure 1.

[0008] 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.