CLIAMS:I claim:

1. A device 100 for monitoring a catalytic converter 300, said device 100 comprising
a temperature electronic control unit (ECU) 101 to calculate a plurality of upstream temperature values of exhaust gas entering said catalytic converter 300 based on at least one engine operating parameter at at least one engine operating point;
a downstream temperature sensor 102 to measure a plurality of downstream temperature values of exhaust gas leaving said catalytic converter 300 at said at least one engine operating point;
said temperature ECU 101 to integrate said upstream temperature values at said at least one engine operating point;
said temperature ECU 101 to integrate said downstream temperature values measured at said at least one engine operating point;
said temperature ECU 101 to calculate a difference between said integrated downstream temperature values and said integrated upstream temperature values; and
said temperature ECU 101 to decide said operating state of said catalytic converter 300 based on said difference.

2. A method for monitoring an operation of a catalytic converter 300, said method comprising
calculating a plurality of upstream temperature values of exhaust gas entering said catalytic converter 300 based on at least one engine operating parameter at at least one engine operating point;
measuring a plurality of downstream temperature values of exhaust gas leaving said catalytic converter 300 at said at least one engine operating point;
integrating said upstream temperature values measured at said at least one engine operating point;

integrating said downstream temperature values measured at said at least one engine operating point;
calculating a difference between said integrated downstream temperature values and said integrated upstream temperature values; and
deciding said operating state of said catalytic converter 300 based on said difference.

3. The method as claimed in claim 2, wherein said operating state is one of a working state or an error state.

4. The method as claimed in claim 2, wherein said engine operating parameters are an air flow rate, a fuel flow rate, an engine coolant temperature and the like.

5. The method as claimed in claim 2, wherein said engine operating point is an engine speed, an engine torque or the like. ,TagSPECI:The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention

[001] The invention relates to a device and method for monitoring a catalytic converter.

Background of the invention

[002] A catalytic converter is a device that uses a catalyst to convert harmful components in a vehicle’s exhaust into harmless compounds. The harmful components are, for example, hydrocarbons, carbon monoxide, and nitrogen oxides. A two-way catalytic converter oxidizes hydrocarbons to carbon dioxide and water, and oxidizes carbon monoxide to carbon dioxide. A three-way catalyst purifies harmful components such as hydrocarbons, carbon monoxide, and nitrogen oxides. During this process enormous amount of heat is released by the chemical reaction and the temperature of the catalyst increases. The catalytic converter ages with time and the conversion efficiency of pollutants reduces. The efficiency of the catalytic converter may also deteriorate over time due to factors such as engine misfire, prolonged operation at high temperatures, etc. Monitoring the operation and working condition of the catalytic converter is required for to inform a user of the vehicle and reduce undesirable emissions of harmful components from the vehicle.

[003] The prior art, US patent 8387365, discloses a device for controlling the operating state of a catalytic converter in the exhaust line of an internal combustion engine, including a mechanism for determining the temperature upstream and downstream of the converter, a mechanism for injecting fuel in the exhaust line of the engine, a mechanism for calibrating a temperature model on a measured operating temperature of the catalytic converter, and a mechanism for calculating the integral of the difference between the measured temperature and the modeled temperature downstream of the converter.

Short description of the drawing

[004] An exemplifying embodiment of the invention is explained in principle below with reference to the drawings. The drawings are,

[005] Figure 1 illustrates a device for monitoring a catalytic converter in accordance with this invention; and

[006] Figure 2 illustrates a flowchart of the method for monitoring the catalytic converter in accordance with this invention.

Description of the invention

[007] Figure 1 illustrates a device 100 for monitoring a catalytic converter 300 in accordance with this invention. The device 100 comprises a temperature electronic control unit (ECU) 101 to calculate a plurality of upstream temperature values of exhaust gas entering the catalytic converter 300 based on at least one engine operating parameter at at least one engine operating point; a downstream temperature sensor 102 to measure a plurality of downstream temperature values of exhaust gas leaving the catalytic converter 300 at the at least one engine operating point; the temperature ECU 101 to integrate the upstream temperature values measured at the at least one engine operating point; the temperature ECU 101 to integrate the downstream temperature values measured at the at least one engine operating point; the temperature ECU 101 to calculate a difference between the integrated downstream temperature values and the integrated upstream temperature values; and the temperature ECU 101 to decide the operating state of the catalytic converter 300 based on the difference.

[008] The temperature ECU 101 calculates the upstream temperature values of exhaust gas entering the catalytic converter 300 based on at least one engine operating parameter at at least one engine operating point. The engine operating parameters are an air flow rate, a fuel flow rate, an engine coolant temperature and the like. The engine operating point is, for example, an engine speed, an engine torque, etc. The temperature ECU 101 communicates with an engine ECU 200 to obtain the engine operating parameters and the engine operating point. The temperature ECU 101 calculates the upstream temperature values based on the engine operating parameter at the engine operating point.

[009] The downstream temperature sensor 102 measures the downstream temperature values of the exhaust gas leaving the catalytic converter 300 at the engine operating point. The downstream temperature sensor 102 is, for example, a resistance temperature detector (RTD) also known as a resistance thermometer. The RTD uses the relationship between an electrical resistance of the RDT and the downstream temperature of the catalytic converter 300 to generate an electrical equivalent value of the downstream temperature to make the value of the downstream temperature compatible with the engine ECU 200.

[0010] The temperature ECU 101 receives the downstream temperature values from the downstream temperature sensor 102 measured at the engine operating point. The temperature ECU 101 integrates the upstream temperature values to obtain an integrated upstream temperature value. The temperature ECU 101 also integrates the downstream temperature values to obtain an integrated downstream temperature value.

[0011] The temperature ECU 101 further calculates the difference between the integrated downstream temperature value and the integrated upstream temperature value. The temperature ECU 101 decides the operating state of the catalytic converter 300 based on the difference. The operating state is one of an working state or an error state. When the difference is greater than a threshold value, the temperature ECU 101 decides that the catalytic converter 300 is in the working state. When the difference is less than the threshold value, the temperature ECU 101 decides that the catalytic converter 300 is in the error state. The error state may refer to a condition when the catalytic converter 300 has deteriorated from a normal working condition. Since the presence of the catalytic converter 300 increases the temperature value at downstream of the catalytic converter 300, when the integrated downstream temperature value is greater than the integrated upstream temperature value, the temperature ECU 101 determines that the catalytic converter 300 is in the working state. When the catalytic converter 300 is in the error state, the integrated downstream temperature value is less than the integrated upstream temperature value. Since a temperature sensor is used to measure the downstream temperature instead of an oxygen sensor, the overall cost of the device 100 is reduced. The efforts of oxygen sensor calibration and diagnosis are also eliminated.

[0012] Figure 2 illustrates a flowchart of the method to control the operation of the engine in accordance with this invention. At step S1, the temperature ECU 101 calculates multiple upstream temperature values of exhaust gas entering the catalytic converter 300 based on at least one engine operating parameter at at least one engine operating point. At step S2, the downstream temperature sensor measures multiple downstream temperature values of exhaust gas leaving the catalytic converter 300 at the at least one engine operating point. At step S3, the temperature ECU 101 integrates the upstream temperature values measured at the at least one engine operating point. At step S4, the temperature ECU 101 integrates the downstream temperature values measured at the at least one engine operating point. At step S5, the temperature ECU 101calculates the difference between the integrated downstream temperature values and the integrated upstream temperature values. At step S5, the temperature ECU 101 decides the operating state of the catalytic converter 300 based on the difference.

[0013] It must be understood that the embodiments explained and the example provided in the above detailed description in only illustrative and does not limit the scope of this invention. The scope of this invention is limited only by the scope of the claims. Many modification and changes in the embodiments aforementioned are envisaged and are within the scope of this invention.