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 monitor a 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 CN114961954, a catalytic converter rear oxygen sensor fault detection method is disclosed. The invention discloses a catalyst rear oxygen sensor fault detection method. The method comprises the following steps: judging whether conditions of a fault detection preparation stage are met or not; if yes, determining the voltage stability of the rear oxygen sensor; after quitting GPF regeneration request air-fuel ratio thinning execution, whether the condition of the fault detection evaluation stage is met or not is judged; if yes, fault evaluation is carried out, and time of T1 is calculated; recording a time interval T2 in which the fluctuation range does not exceed a second preset value when the conditions of the oxygen sensor in the fault detection and evaluation stage are met after reality; if the absolute value of the difference between T1-T2 exceeds C1, the rear oxygen sensor has a fault; if the absolute value of the difference between the T1-T2 does not exceed C2, the rear oxygen sensor has no fault; c1 is greater than or equal to C2. According to the method, the air-fuel ratio is enriched after the air-fuel ratio thinning control is finished, whether the rear oxygen sensor breaks down or not is monitored by monitoring the performance of the voltage of the rear oxygen sensor after the air-fuel ratio is enriched, and the phenomenon of excessive NOx in emission is improved.

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 monitor 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 monitoring 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 monitor 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 two temperature inputs from two temperature measuring probes out of which the first temperature input is from a first temperature sensor 116 at the position of the mid-catalyst where the catalytic action occurs, and the second temperature input is from a second temperature sensor 118 at post-catalytic position which needs to be fixed optimally as per the optimum fixing criteria.

[0009] The controller 110 makes use of the principle of exothermic temperature of 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 configured to measure the first temperature, using the first temperature sensor 116, at mid-point of the TWC 106, receive/determine the second temperature, using a second temperature determining means, post the TWC 106 and calculate a relational value between the first temperature and the second temperature in a drive cycle which are measured/determined at the same time. The second temperature determining means comprises any one of a second temperature sensor 118 or a temperature model as known in the art. The first temperature sensor 116 and the second temperature determining means measures and determines the respective temperature continuously in real-time at every time instant and do not correspond to a single value, but to a series of values. The controller 110, characterized in that, configured to process the calculated relational values using the computational module 120. The controller 110 then determines ageing (or aging) of the TWC 106 based on comparison of an output of the computational module 120 with the respective threshold value. The threshold value is stored separately for the difference and ratio based relational values.

[0015] The TWC 106 is any one of a single brick catalyst and a multi brick catalyst. The first temperature is considered for any one of a first positioned brick, a last positioned brick and intermediately positioned brick in the multi brick catalyst. Further, the multi brick catalyst is any one of a tandem catalyst and a split catalyst. The single brick catalyst and the multi brick catalyst are of same capacity.

[0016] According to an embodiment of the present invention, the computational module 120 is configured to perform operations selected from a group comprising averaging, normalization, scaling, delta change, integration, differentiation, cumulative sum, and binning. The operations are defined below.

[0017] The averaging operation comprises averaging the relational values such as, moving average or rolling average over period or time or samples, at a particular mass-flow and lambda operating conditions of the drive cycle (thus not mandatorily the entire drive cycle). If the average of the relational value (ratio or difference) crosses the calibratable threshold, then the ageing of the TWC 106 is determined by the controller 110 followed by reporting. If the average of the relational value crosses the threshold value abnormally based on operating point (air-intake charge) then misfiring is be detected.

[0018] In case of the normalization operation, the controller 110 normalizes the relational values to a factor (for example 0 to 1). Assume if the threshold is calibrated to 0.7 based on a drive cycle (at a particular air-mass-flow intake and lambda one operation). Now, if the normalized value exceeds the threshold of 0.7, the controller 110 determines the TWC 106 to be aged followed by reporting. If the normalized value crosses, say abnormally to 1 or more than 1, then the controller 110 determines the event to be misfiring. The values are just for explanation and will be different upon implementation.

[0019] In case of the squaring/scaling operation, if the relational value is very small based on application, then the relational value is squared or scaled (more than 1 or less than 1) and is then usable for comparison with threshold value for determination of the ageing of the TWC 106. For example, when the ratio at fresh state is 1.2 and aged state is 1.4. Then scaling or squaring would make easier to differentiate the ageing.

[0020] In case of delta change operation, where percentage (%) change in the relational value is considered, the change of the relational value is monitored over time and/or distance (example Number of Kilo meters) the vehicle 100 ran. The delta change gives the trend of ageing. For example, say durability limit of 20,000 kms or 35,000 kms and or some percentage of On-board Threshold Limit (OTL), depending on customer requirements and legislation. The values put in durability and OTL state are purely based on legislation and are not fixed.

[0021] In case the operation is integration, the relational value at a particular drive cycle (constant steady mass-flow and lambda running conditions) is integrated over period at a constant load point (air-mass-flow) and lambda one conditions of the drive cycle, and threshold value is set accordingly (based on load and lambda operation of the vehicle 100). This operation predicts the total amount of ageing of the TWC 106 accurately.

[0022] If the operation is differentiation, the relational value at a particular drive cycle (constant steady mass-flow and lambda running conditions) is differentiated over period at a constant load point (air-mass-flow) and lambda one conditions of the drive cycle, and threshold value is set accordingly (based on load and lambda operation of the vehicle 100). This operation enables prediction of the total amount of ageing of the TWC 106 accurately.

[0023] If the cumulative sum is the operation, the relational value is summed up by the controller 110 and then the compared with a calibratable threshold for determination of the ageing of the TWC 106.

[0024] If the binning is operation, the controller 110 bins the relational value into range or categories. For example, in a test, assume 100 ratios are recorded (at certain raster), one or more number of bins would be defined based on values and out of 100 may be 20 falls under first bin and 70 falls under second bin, and 10 falls out of bin which can be discarded or stored in a dummy bin. The threshold value is set based on number of values that falls under each bin and catalyst ageing is determined accordingly. Alternatively, the weighted average of all bins is considered, and variance or standard deviation could be calculated and based on the deviation the threshold value could be set accordingly to report catalyst ageing.

[0025] According to an embodiment of the present invention, the computational module 120 is performed during a predetermined conditions 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 sensor 114. 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 upstream O2 sensor 114 readiness, 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.

[0026] Further, the threshold value for the relational 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. The threshold value is either same or different for determination of ageing of the TWC 106. The relational value is possible to be either new state and aged state or vice-versa. Hence with this aspect there would be change in magnitude for the calibratable threshold and would be altered accordingly. For example, if ratio is the selected/configured relational value, then the ratio is either between the first temperature and second temperature or second temperature and the first temperature. Similarly, if the difference is the relational value, then the difference is either between the first temperature and the second temperature, or second temperature and the first temperature.

[0027] 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.

[0028] 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.

[0029] 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, the temperature probes/sensor are installed on middle of the TWC 106 and post-catalyst position. 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 temperature sensor probes are installed on middle of the first catalyst 106 (from engine out) and post catalyst position. Alternatively, the first temperature sensor 106 is positioned on the middle of the second of the tandem catalyst. In a third configuration 126, the catalyst 106 is split, and the temperature sensor probes are installed on the middle of primary (first) catalyst 106 and post-primary catalyst 106.

[0030] 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.

[0031] 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.

[0032] As per a first strategy, the controller 110 calculates the difference in temperature from mid-catalyst (shown in strip 3 in Fig.2) and post-catalyst (shown in strip 5 in Fig. 2) and is compared against a pre-calibrated threshold (which is calibrated for a worst aged conditions). Due to the ageing effects, the exothermic temperature of the catalyst drops. The smaller is the difference, the much is the catalyst being aged. As per a second strategy, the controller 110 calculates the ratio of temperatures from mid-catalyst (shown in strip 3 in Fig.2) and post-catalyst (shown in strip 5 in Fig. 2) and is compared against a pre-calibrated threshold (which is calibrated for a worst aged conditions). Due to the ageing effects, the exothermic temperature of the catalyst drops where the magnitude of the ratio drops. Lower the ratio, much is cat ageing.

[0033] A second graph 210 shows the temperature plot of a typical two-wheeler vehicle 100 which was run with a World Motorcycle Test Cycle (WMTC). A first plot 202 shows the temperature profile for mid-catalyst and a second plot 204 shows the temperature profile for post catalyst. The difference in temperature is clearly visible.

[0034] Since the difference or ratio of temperatures 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. This system may include lots of corrections, scaling, smoothening of acquired signals at a defined cycle to perform diagnosis.

[0035] Fig. 3 illustrates a method flow diagram for monitoring the TWC in the exhaust conduit of the vehicle, according to the present invention. The method comprises plurality of steps of which a step 302 comprises measuring the first temperature, by the first temperature sensor 116, at mid-point of the TWC 106. A step 304 comprises receiving/determining the second temperature, by the second temperature determining means, post the TWC 106. The second temperature determining means comprises any one of the second temperature sensor 118 and the temperature model as known in the art. The fist temperature and the second temperature are continuously measured, determined by respective sensors/means and stored in the memory element 108. A step 306 comprises calculating, by the controller 110, the relational value between the first temperature and the second temperature in the drive cycle, which are measured/determined at the same time. The method is characterized by a step 308 which comprises processing, by the controller 110, the relational values using the computational module 120. A step 310 comprises determining, by the controller 110, aging of the TWC 106 based on comparison of the output of the computational module 120 with the respective threshold value. The method is performed or executed by the controller 110.

[0036] According to the method, the TWC 106 is any one of the single brick catalyst and the multi brick catalyst. The first temperature is considered for a first positioned brick, a last positioned brick and intermediately positioned brick in the multi brick catalyst. The multi brick catalyst is any one of the tandem catalyst and the split catalyst. The single brick catalyst and the multi brick catalyst are of same capacity. The computational module 120 as mentioned in step 308, is configured to perform operations selected from the group comprising averaging, normalization, scaling, delta change, integration, differentiation, cumulative sum, and binning.

[0037] According to the present invention, the computational module 120 is performed during a predetermined conditions of the drive cycle. The description is not repeated here and is already provided above.

[0038] According to the present invention, the controller 110 and method to monitor the TWC 106 using temperature measuring probes/sensors 116, 118 and/or calculated modelling temperatures is disclosed. The present invention provides innovative solution which comprises two temperature measuring probes/sensors 116, 118 at mid catalyst position and post-catalyst position respectively, the difference in temperature (or ratio of temperature) is computed and compared with the threshold value and the catalyst ageing is reported. The controller 110 requires a cost-effective and simple hardware-software interface compared to that of O2 sensor system architecture. The temperature probes/sensors 116, 118 are simpler, cheaper, and more durable also they can withstand high temperatures and harsh environments. The controller 110 is able to monitor the ageing of the TWC 106 and detect misfiring based on temperature probes as per the legislation requirements and fulfill the In-Use Monitor Performance Ratio (IUMPR) standards. The controller 110 helps diagnose the issue pertaining to the TWC 106 to the end user by turning ON the MIL.

[0039] 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.

[0040] 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 monitor a Three-Way Catalyst (TWC) (106) in an exhaust conduit (104) of a vehicle (100), said controller (110) configured to,
measure first temperature, by a first temperature sensor (116), at mid-point position of said TWC (106);
receive second temperature, by a second temperature determining means, at post-catalyst position of said TWC (106),
calculate relational values between said measured first temperature and said measured second temperature in a drive cycle, characterized in that,
process said relational values using a computational module (120), and
determine aging of said TWC (106) based on comparison of an output of said computational module (120) with a respective threshold value.

2. 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 said first temperature is considered for any one of a first positioned brick, a last positioned brick and intermediately positioned brick in said multi brick catalyst.

3. The controller (110) as claimed in claim 2, wherein said multi brick catalyst is any one of a tandem catalyst and a split catalyst, wherein said single brick catalyst and said multi brick catalyst are of same capacity.

4. 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 averaging, normalization, scaling, delta change, integration, differentiation, cumulative sum, and binning.

5. The controller (110) as claimed in claim 1, wherein said computational module (120) is performed during a predetermined conditions of said drive cycle.

6. A method for monitoring a Three-Way Catalyst (TWC) (106) in an exhaust conduit (104) of a vehicle (100), said method comprising the steps of:
measuring first temperature, by a first temperature sensor (116), at a mid-point position of said TWC (106);
receiving second temperature, by a second temperature determining means, at a post-catalytic position of said TWC (106),
calculating relational values between said first temperature and said second temperature in a drive cycle, characterized by,
processing said relational values using a computational module (120), and
determining aging of said TWC (106) based on comparison of an output of said computational module (120) with a respective threshold value.

7. 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 said first temperature is considered for a first positioned brick, a last positioned brick and intermediately positioned brick in said multi brick catalyst.

8. The method as claimed in claim 7, wherein said multi brick catalyst is any one of a tandem catalyst and a split catalyst, wherein said single brick catalyst and said multi brick catalyst are of same capacity.

9. The method as claimed in claim 6, wherein said computational module (120) is configured to perform operations selected from a group comprising averaging, normalization, scaling, delta change, integration, differentiation, cumulative sum, and binning.

10. The method as claimed in claim 6, wherein said computational module (120) is performed during a predetermined conditions of said drive cycle.