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 disclosure relates to a controller and method to determine aging of Three-Way Catalyst (TWC) in an exhaust conduit of a vehicle.

Background of the invention:
[0002] A Three-Way Catalysts (TWC) is an apparatus that reduce the emissions of harmful gases from the combustion of gasoline fuel in automobiles. The TWC convert carbon monoxide, hydrocarbons, and nitrogen oxides into carbon dioxide, water, and nitrogen, respectively. They require a precise control of the air-fuel ratio to maintain their efficiency and durability. An On-board Diagnostics (OBD) is a system that monitors and reports the status of the vehicle’s components and systems. The OBD can detect any malfunction or deterioration of the three-way catalysts and alert the driver by illuminating the Malfunction Indicator Light (MIL), also known as the check engine light. The system provides the solution to monitor the life of TWC and helps reporting the issue to the end user by turning on the MIL. The current solution for catalyst monitoring uses O2 measuring probes to detect the oxygen content post catalyst and based on the amplitudes or active response of the sensor, the catalyst ageing is reported.

[0003] According to a prior art EP3705693, a method for evaluating ageing of a three-way catalyst is disclosed. The invention discloses A method for evaluating ageing of a three-way catalyst is provided for an assembly, which has a spark ignition internal combustion engine, a lambda sensor (LSF) arranged downstream of the catalyst, and an injection device which is controlled to supply fuel to the engine according to a set-point, indicative of a desired air/fuel ratio during combustion of a mixture of fuel and air in the engine; according to the method, a wobbling pattern for the set-point is set so as to operate the engine with alternating lean combustion phases and rich combustion phases; a parameter indicative of signal amplitude has a value calculated in relation to an actual output signal (U) of the lambda sensor; a possible mismatch between this value and a reference is evaluated so as to identify a possible ageing condition of the catalyst.

Brief description of the accompanying drawings:
[0004] An embodiment of the disclosure is described with reference to the following accompanying drawings,
[0005] Fig. 1 illustrates a block diagram of a controller to determine aging of a Three-Way Catalyst (TWC) in an exhaust conduit of a vehicle, according to an embodiment of the present invention, and
[0006] Fig. 2 illustrates a temperature pattern across the exhaust conduit, according to the present invention, and
[0007] Fig. 3 illustrates a method flow diagram for determining the aging of the TWC in the exhaust conduit of the vehicle, according to the present invention.

Detailed description of the embodiments:
[0008] Fig. 1 illustrates a block diagram of a controller to determine aging of a Three-Way Catalyst (TWC) in an exhaust conduit of a vehicle, according to an embodiment of the present invention. A gasoline automobile/vehicle 100 consists of the three-way catalyst (TWC) 106 to convert the harmful gases to less harmful which are coming out of an engine 102 due to incomplete combustion. A catalyst monitoring control system or the controller 110 takes input, primarily from the oxygen sensor 116 positioned downstream position of the TWC 106.

[0009] The controller 110 makes use of the principle of exothermic temperature of the exhaust gases and the TWC 106. The TWC 106 consists of a ceramic or metallic substrate coated with a thin layer of washcoat that contains Precious Group Metals (PGM) such as Platinum, Palladium and Rhodium. The washcoat also contains oxygen storage components (OSC) such as cerium oxide that can store and release oxygen as needed. The TWC 106 operates in a narrow range of air-fuel ratio around the stoichiometric point, where the amount of oxygen and fuel are balanced. The TWC 106 is able to perform three main reactions: oxidation of carbon monoxide (CO) and hydrocarbons (HC) to carbon dioxide (CO2) and water (H2O), and reduction of nitrogen oxides (NOx) to nitrogen (N2). These reactions are exothermic, where they release heat to the surroundings. The exothermic temperature of the TWC 106 depends on several factors, such as the composition and loading of the wash coat, the inlet gas temperature, the air-fuel ratio, the flowrate, and the catalyst aging and the ambient conditions.

[0010] The exothermic reactions that occur within the TWC 106 are as follows:
Oxidation of CO: CO + 0.5 O2 ? CO2 + heat
Oxidation of HC: CnHm + (n + m/4) O2 ? n CO2 + m/2 H2O + heat
Reduction of NOx: NO + CO ? 1/2 N2 + CO2 + heat

[0011] The oxidation reactions require oxygen to proceed, while the reduction reaction consumes oxygen. Therefore, the TWC 106 needs to balance the oxygen supply and demand by using the OSC. When there is excess oxygen in the exhaust gas, the OSC can store some of it for later use. When there is a lack of oxygen in the exhaust gas, the OSC can release some of it to maintain the oxidation reactions. The OSC also helps to buffer the fluctuations in the air-fuel ratio and prevent rapid changes in the catalyst temperature.

[0012] The catalyst aging is a phenomenon that reduces the catalytic activity and performance over time. The main causes of catalyst aging are thermal degradation, chemical poisoning, and mechanical damage. Thermal degradation occurs when the TWC 106 is exposed to high temperatures for prolonged periods, which can cause sintering of the PGM particles, loss of washcoat porosity, phase transformation of the OSC and washcoat support, and decrease in surface area. The chemical poisoning occurs when some contaminants in the exhaust gas or fuel, such as sulfur, phosphorus, lead, zinc, and silicon, bind to the active sites of the PGM or OSC and block their activity. A mechanical damage occurs when the TWC 106 is subjected to vibrations, shocks, or thermal stresses, which can cause cracks, fractures, or detachment of the washcoat from the substrate.

[0013] The catalyst aging affects the exothermic temperature of the TWC 106 by reducing its ability to perform the oxidation and reduction reactions. As a result, more unreacted gases pass through the TWC 106 without being converted, which lowers the heat generation. Therefore, an aged TWC 106 has a lower exothermic temperature than a fresh/new one.

[0014] According to the present invention, the controller 110 to determine aging of the Three-Way Catalyst (TWC) 106 in the exhaust conduit 104 of the vehicle 100 is provided. The exhaust conduit 104 comprises the oxygen sensor 116 (primary oxygen sensor 116) with a heating element 118, also referred to as heated oxygen sensor 116. The controller 110 configured to control supply of electrical power/voltage, form a source (such as battery, generator/alternator), to the heating element 118 to maintain a working temperature requirement for the oxygen sensor 116. The oxygen sensor 116 is installed in the downstream position of the TWC 106. The controller 110, characterized in that, configured to monitor a value of the electrical power/voltage, process the monitored value with a computational module 120 and compare the processed value with a threshold. The controller 110 determines aging of the TWC 106 based on the comparison. The primary oxygen sensor 116 or oxygen sensor 116 is positioned downstream of the TWC 106.

[0015] According to the present invention, the value is at least one of a direct monitored value of the electrical power/voltage and a duty cycle of the electrical power/voltage. The electrical power/voltage is supplied from a battery of the vehicle 100, but controlled by the controller 110.

[0016] According to the present invention, the computational module 120 is configured to perform at least one operation selected from group comprising differences between the value and a reference, ratio of the value and the reference and integration of the value over distance recorded/travelled. The reference corresponds to value which is the voltage/power that is drawn/consumed or duty cycle of the voltage/power, by the same oxygen sensor 116 at the fresh/new state of the TWC 106 or a secondary oxygen sensor 114 is used. The secondary oxygen sensor 114 is optional and is positioned upstream of the TWC 106.

[0017] According to an embodiment of the present invention, the value is monitored and processed under two conditions. A first condition comprises presence of a predetermined operating zone of the engine 102 of the vehicle 100, and a second condition comprises presence of a stoichiometric air-fuel ratio. As per the second condition, a signal from the secondary oxygen sensor 114 is used if available, otherwise the signal from the primary oxygen sensor 116 is used. Further, if the signal from the primary oxygen sensor 116 is used, then the system corresponds to a Single Lambda Control System (SLCS). Thus, the lambda control and diagnosis of the TWC 106 is performed by the single oxygen sensor 116 which is positioned downstream of the TWC 106.

[0018] According to the present invention, the TWC 106 is any one of a single brick catalyst and a multi brick catalyst. The primary oxygen sensor 116 is positioned after at least a first positioned brick in the multi brick catalyst. The single brick catalyst and the multi brick catalyst are of same capacity.

[0019] According to an embodiment of the present invention, the computational module 120 processes the value during a predetermined conditions (indicated above) of the drive cycle. The part of the drive cycle which are under steady state conditions are considered for determination of ageing of the TWC 106. The steady state conditions are those where the exothermic temperature of the TWC 106 is stable. The conditions considered for the drive cycle are for example, only at Lambda 1 (absolute or on average, preferably when the upstream lambda = 0.99 to 1.01 on average (can be lot narrower as-well)), engine operating temperature is within permissible range, and there is constant absolute air-charge. The Lambda value is measured by the lambda/O2/ oxygen sensor 114, 116. Similarly, other parameters of the engine 102 such as air mass flow rate, engine temperature, manifold air pressure and the like are measured by respective sensors 112 such as a flow rate sensor, engine temperature sensor, a manifold air pressure sensor, and the like. The stable operating zones of the engine 102 are some of the other conditions that are necessary. In addition, various inputs such as air intake temperature, ambient temperature, gradients/elevation, fuel injection parameters are also considered whenever required for considering the operating zones of the engine 102.

[0020] Further, the threshold for the processed value is calibratable and possible to be dynamically corrected based on pressure gradients, air intake temperature, ambient temperature, air intake in-terms of mass-flow as-well. If the processed value is the ratio, then the ratio is either between the monitored value and the reference or reference and the monitored value. Similarly, if the processed value is the difference, then the difference is either between the monitored/measured value and the reference, or the reference and the monitored value.

[0021] In accordance to an embodiment of the present invention, the controller 110 is provided with necessary signal detection, acquisition, and processing circuits. The controller 110 is the one which comprises input interface, output interfaces having pins or ports, the memory element 108 such as Random Access Memory (RAM) and/or Read Only Memory (ROM), Analog-to-Digital Converter (ADC) and a Digital-to-Analog Convertor (DAC), clocks, timers, counters and at least one processor (capable of implementing machine learning) connected with each other and to other components through communication bus channels. The memory element 108 is pre-stored with logics or instructions or programs or applications or modules/models and/or threshold values/ranges, reference values, predefined/predetermined criteria/conditions, which is/are accessed by the at least one processor as per the defined routines. The internal components of the controller 110 are not explained for being state of the art, and the same must not be understood in a limiting manner. The controller 110 may also comprise communication units such as transceivers to communicate through wireless or wired means such as Global System for Mobile Communications (GSM), 3G, 4G, 5G, Wi-Fi, Bluetooth, Ethernet, serial networks, and the like. The controller 110 is implementable in the form of System-in-Package (SiP) or System-on-Chip (SOC) or any other known types. Examples of controller 110 comprises but not limited to, microcontroller, microprocessor, microcomputer, etc.

[0022] Further, the processor may be implemented as any or a combination of one or more microchips or integrated circuits interconnected using a parent board, hardwired logic, software stored in the memory element 108 and executed by a microprocessor, firmware, an application specific integrated circuit (ASIC), and/or a field programmable gate array (FPGA). The processor is configured to exchange and manage the processing of various Artificial Intelligence (AI) modules.

[0023] According to an embodiment of the present invention, the controller 110 is implementable in different types of catalyst configurations. The configurations are shown with engine 102 in left and exhaust conduit 104 as a line to the right. In a first configuration 122, the TWC 106 is single and big, a secondary oxygen sensor 114 (optional) is positioned upstream of the TWC 106 and the primary oxygen sensor 116 positioned downstream of the TWC 106. In a second configuration 124, the TWC 106 is tandem (two small catalysts 106 in a single outer casing or two small catalysts with negligible distance between them). The secondary oxygen sensor 114 is positioned upstream of the TWC 106 and the primary oxygen sensor 116 is positioned downstream of the second brick of the TWC 106. The primary oxygen sensor 116 is also possible to be positioned in between the bricks of the tandem catalyst, shown in dotted pattern. In a third configuration 126, the TWC 106 is split, and the secondary oxygen sensor 114 is positioned upstream of the TWC 106 and the primary oxygen sensor 116 is positioned downstream of the first brick of the TWC 106. The primary oxygen sensor 116 is also possible to be positioned after the last brick of the split type TWC 106, shown in dotted patterns. The downstream position of the primary oxygen sensor 116 is such that the primary oxygen sensor 116 is exposed to the maximum of the generated heat. The primary oxygen sensor 116 shown in dotted pattern is to depict alternate position. The heating element 118 is not shown in the dotted pattern for simplicity, but the same must not be understood in limiting manner.

[0024] According to an embodiment of the present invention, the vehicle 100 is any one of a two-wheeler such as motorcycle, three-wheeler such as auto-rickshaws, a four wheeler such as car and other vehicles 100 where the use of TWC 106 is done. Further, the vehicle 100 runs on at least one fuel selected from a group comprising a gasoline/petrol, an ethanol blended with gasoline (E0-E100), a Compressed Natural Gas (CNG), a Liquefied Petroleum Gas (LPG) and the like.

[0025] According to the present invention, a working of the controller 110 is explained using the Fig. 1. The primary oxygen sensor 116 such as switching type oxygen/lambda sensor, works on close loop heating strategy. The close loop heating is the voltage/power drawn from the battery after taking the feedback of the temperature of the heating element 118 of the installed primary oxygen sensor 116. The voltage/power/ duty cycle is reduced or increased based on the present working temperature of the primary oxygen sensor 116. The primary oxygen sensor 116 operate at one desired temperature such as 620degC, ~700degC, etc., at all operating conditions to maintain the accuracy of lambda measured. Hence, the primary oxygen sensor 116 with close loop strategy is required. The controller 110 is configured to implement the close loop heater strategy.

[0026] The heater voltage of the secondary oxygen sensor 114 is purely influenced by the heat of the exhaust gases at various operating zones of the engine 102. The voltage of the primary oxygen sensor 116 is influenced by the heat of the exothermic gases that are coming out of the TWC 106 (as redox reactions effectively are exothermic in nature). Hence, the placement/positioning of the primary oxygen sensor 116 is as close as to that of the TWC 106 instead of placing it sufficiently far, such that the primary oxygen sensor 116 is exposed to maximum of the exothermic heat.

[0027] On ageing of the TWC 106, the exothermic heat gets dropped within the catalyst such that the primary oxygen sensor 116 requires a higher power/effective voltage to maintain the same desired temperature of sensor operation. Hence the power/voltage or duty cycle utilization of the downstream close loop heated oxygen sensor 116 is compared with the reference which is the voltage /power that is drawn by the same oxygen sensor 116 at the fresh state of the TWC 106 by the computation module 120. By computing the processed value, i.e. the difference or ratio or integral over time is obtained, and the controller 110 compares with the calibratable and application dependent threshold. Once the threshold is crossed, the ageing of the TWC 106 is reported at one particular operating point of the vehicle 100. Here it is to be noted that input from secondary oxygen sensor 114 is not used for catalyst diagnosis but is only used to measure the lambda value itself as needed in the second condition.

[0028] Fig. 2 illustrates a temperature pattern across the exhaust conduit, according to the present invention. A first graph 200 is shown overlapped with the layout of the exhaust conduit 104 where temperature is plotted against position. The temperature is shown in Y-axis in suitable unit such as Celsius, and position is shown in X-axis. The temperature pattern increases and decreases in a typical exhaust conduit 104 where there is a presence of the TWC 106. At a steady particular operating point of the vehicle 100 where the ambient conditions are normal, the temperature decreases as it goes far against the combustion chamber due to ambient cooling and heat exchange. Due to the presence of the TWC 106 in-between, there occurs a red-ox reaction which is exothermic in nature (releases heat) with the presence of precious materials (catalytic activity accelerators) results in increase in temperature as shown in strip (3), and the temperature drop is expected across the exhaust conduit/path 104 due to heat exchange actions.

[0029] A second graph 210 shows the temperature plot of a typical two-wheeler vehicle 100 which was run X distance from the start. A X-axis 204 represents ageing/aging of the TWC 106 on distance travelled in Kilometers. A Y-axis 202 represents power in (KW) and voltage (V) or duty cycle of power/voltage required to heat the primary oxygen sensor 116 at desired temperature of sensor operation. A first plot 206 shows the integral of the effective voltage/power required for primary oxygen sensor 116 at the start or fresh state of the TWC 106, in an ideal scenario, for the entire duration of the distance travelled. A second plot 208 shows the actual voltage/power consumption or duty cycle used for the entire duration of the distance X. The difference between the first plot 206 and the second plot 208 indicates aging.

[0030] Since the difference or ratio or integral of the values are depended on various factors such as operating points of the vehicle 100, the controlling action and diagnosis would be conducted on operating zones basis. The optionally includes include lots of corrections, scaling, smoothening of acquired signals at a defined cycle to perform diagnosis.

[0031] Fig. 3 illustrates a method flow diagram for determining the aging of the TWC in the exhaust conduit of the vehicle, according to the present invention. The exhaust conduit 104 comprises the oxygen sensor 116 with the heating element 118. The method comprises plurality of steps of which a step 302 comprises controlling supply of electrical power/voltage to the heating element to maintain the working temperature requirement for the primary oxygen sensor 116. The primary oxygen sensor 116 is installed in at least downstream position of the TWC 106. The method is characterized by, a step 304 which comprises monitoring the value of the electrical power/voltage. A step 306 comprises processing the monitored value with the computational module 120 and comparing the processed value with the threshold. A step 308 comprises determining aging of the TWC 106 based on the comparison.

[0032] According to the method, the value is at least one of the direct monitored value of the electrical power/voltage and the duty cycle of the electrical power/voltage. The computational module 120 is configured to perform at least one operation selected from a group comprising differences, ratio, and integration of the value to determine/compute processed value.

[0033] According to the method, the value is monitored and processed under two conditions. The first condition comprises presence of the predetermined operating zone of the engine 102 of the vehicle 100. The second condition comprises presence of the stoichiometric air-fuel ratio. The second condition is achieved either by the secondary oxygen sensor 114 (if available) or by the primary oxygen sensor 116 itself.

[0034] Further, the TWC 106 is any one of the single brick catalyst and the multi brick catalyst. The primary oxygen sensor 116 is positioned after at least the first positioned brick in said multi brick catalyst.

[0035] According to the present invention, the controller 110 and method to monitor the ageing of TWC 106 using the power source utilized by single (downstream) close loop heated oxygen sensor 116 in automobile applications is disclosed. The inventive step or technical advantage of the preset invention comprises the use of single close loop heated oxygen sensor 116 placed downstream of the TWC 106, but instead of sensing the oxygen content and reporting the catalyst ageing, the power utilization (voltage utilization) or duty cycle/ratio to heat the oxygen sensor 116 to the desired temperature is used and the ageing of the TWC 106 is reported. The present invention does not require any hardware changes or additional cost compared to the previous state of arts, but only require a small software/program addition to the controller 110. Alternatively the existing control unit of the vehicle 100 is replaced with the new controller 110 as per the present invention. The controller 110 and method monitors the ageing of the TWC 106 as per the legislation requirements and fulfill the In-Use Monitor Performance Ratio (IUMPR) standards. Further, the controller 110 and method diagnoses the issue pertaining to the TWC 106 to the end user by turning ON the MIL.

[0036] According to the present invention, by monitoring the TWC 106, the environmental impact of automobile emissions is possible to be reduced by ensuring that the catalysts are working properly and efficiently. This also enhances the fuel economy and performance of the vehicle 100. The OBD helps find and fix any problem with the TWC 106, such as damage, contamination, or aging. Further, the OBD helps technicians to perform timely and accurate repairs and prevent further damage to the engine 102 or other components. The OBD also helps comply with the emission regulations and standards that are becoming increasingly stringent in many countries. The OBD can provide evidence of the emission performance of the vehicle 100 and alert the authorities if any tampering or modification of the catalysts has occurred.

[0037] 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.
, Claims:We claim:
1. A controller (110) to determine aging of Three-Way Catalyst (TWC) (106) in an exhaust conduit (104) of a vehicle (100), said exhaust conduit (104) mounted with an oxygen sensor (116) having a heating element (118), said controller (110) configured to:
control supply of electrical power/voltage from a source to said heating element (118) to maintain a working temperature requirement for said oxygen sensor (116), said oxygen sensor (116) installed at a downstream position of said TWC (106), characterized in that,
monitor a value of said electrical power/voltage;
process the monitored value with a computational module (120) and compare the processed value with a threshold, and
determine aging of said TWC (106) based on the comparison.

2. The controller (110) as claimed in claim 1, wherein said value is at least one of a direct monitored value of the electrical power/voltage and a duty cycle of the electrical power/voltage.

3. The controller (110) as claimed in claim 1, wherein said computational module (120) is configured to perform at least one operation selected from a group comprising differences, ratio, and integration of said value to determine said processed value.

4. The controller (110) as claimed in claim 1, wherein said value is monitored and processed under two conditions, wherein a first condition comprises, presence of a predetermined operating zone of an engine (102) of said vehicle (100), and a second condition comprises, presence of a stoichiometric air-fuel ratio of exhaust gas.

5. The controller (110) as claimed in claim 1, wherein said TWC (106) is any one of a single brick catalyst and a multi-brick catalyst, wherein in case of said multi-brick catalyst, said oxygen sensor (116) is positioned after at least a first positioned brick of said multi-brick catalyst.

6. A method for determining aging of Three-Way Catalyst (TWC) (106) in an exhaust conduit (104) of a vehicle (100), said exhaust conduit (104) comprises an oxygen sensor (116) having a heating element (118), said method comprising the steps of:
controlling supply of electrical power/voltage, from a source, to said heating element (118) to maintain a working temperature requirement for said oxygen sensor (116), said oxygen sensor (116) installed in at least one of an upstream position and a downstream position of said TWC (106), characterized by,
monitoring a value of said electrical power/voltage;
processing the monitored value with a computational module (120) and compare the processed value with a threshold, and
determining aging of said TWC (106) based on the comparison.

7. The method as claimed in claim 6, wherein said value is at least one of a direct monitored value of the electrical power/voltage and a duty cycle of the electrical power/voltage.

8. The method as claimed in claim 6, wherein said computational module (120) is configured to perform at least one operation selected from a group comprising differences, ratio, and integration of said value to determine said processed value.

9. The method as claimed in claim 6, wherein said value is monitored and processed under two conditions, wherein a first condition comprises, presence of a predetermined operating zone for an engine (102) of said vehicle (100), and a second condition comprises, presence of a stoichiometric air-fuel ratio of exhaust gas.

10. The method as claimed in claim 6, wherein said TWC (106) is any one of a single brick catalyst and a multi brick catalyst, wherein incase of said multi-brick catalyst, said oxygen sensor (116) is positioned after at least a first positioned brick of said multi brick catalyst.