Description:Technical Field
The present invention relates to a system and a method of detecting a quality of urea after refill in a Selective Catalytic Reduction system.

Background
Selective Catalytic Reduction (SCR) technology is a well-known technology in the field of automobile emissions. The SCR utilizes diesel exhaust fluid (DEF) to significantly reduce oxides of nitrogen (NOX) emissions by converting NOX into nitrogen and water. DEF is an aqueous urea solution made with urea (32.5 %) and water (67.5%).
Fig. 1 shows a relationship between urea concentrations in the DEF, NOX emissions and conversion efficiency of the SCR (from NOX to nitrogen and water). As shown in Fig. 1, with the increase in urea concentration in the DEF, the amount of NOX emissions decreases. Further, with the increase in urea concentration in the DEF, the conversion efficiency of SCR also increases.
However, the automobile owners, in order to save cost of DEF, re-fill abnormal quality DEF into the DEF tank of the automobile. This abnormality is achieved due to adulteration of more water into the DEF than the standard 67.5%. This results into abnormality in overall urea quality as the urea quantity falls below the standard 32.5%.
Therefore, there is a need for a system and method of detecting quality of urea after refill for the SCR. There is also a need for a system and method of detecting abnormality and normality in quality of urea after refill for the SCR.
Summary
Accordingly, one aspect of the present invention relates to a method for detecting a quality of urea after refill for a Selective Catalytic Reduction (SCR). The method comprising: receiving, by a control system, a signal of urea refill; shutting-off an engine gas recirculation (EGR), on a command of the control system, while keeping an amount of diesel exhaust fluid reaching the SCR constant, wherein the shutting-off of the EGR results in receiving of a higher amount of NOX by the SCR than a standard NOX amount. Further step includes, calculating a conversion efficiency (CE) of the SCR, by the control system, based on difference of NOX reaching the SCR and exiting the SCR. Subsequently, the next step involves comparing (CP), by the control system, the calculated CE with a threshold conversion efficiency to detect the quality of the urea refill.
Accordingly, one aspect of the present invention relates to a system for detecting a quality of urea after refill for a Selective Catalytic Reduction (SCR). The system comprising: a control system configured to receive a signal of urea refill; shut-off an engine gas recirculation (EGR), while keeping an amount of diesel exhaust fluid reaching the SCR constant, wherein the shutting-off of the EGR results in receiving of a higher amount of NOX by the SCR than a standard NOX amount; calculate a conversion efficiency (CE) of the SCR based on difference of NOX reaching the SCR and exiting the SCR; and compare (CP) the calculated CE with a threshold conversion efficiency to detect any one of the abnormality and the normality in quality of the urea after refill.
Yet another aspect of the present invention relates to a method for detecting an abnormality in quality of urea after refill for a Selective Catalytic Reduction (SCR). The method comprising: receiving, by a control system, a signal of urea refill; shutting-off an engine gas recirculation (EGR), on a command of the control system, while keeping an amount of diesel exhaust fluid reaching the SCR constant, wherein the shutting-off of the EGR results in receiving of a higher amount of NOX by the SCR than a standard NOX amount. Further, step includes calculating a conversion efficiency (CE) of the SCR, by the control system, based on difference of NOX reaching the SCR and exiting the SCR and comparing (C1), by the control system, the calculated CE with a threshold conversion efficiency. Further, the next step includes regenerating the SCR, on the command of the control system, based the comparison (C1); re-calculating the conversion efficiency (CE) of the SCR , by the control system , based on difference of NOX reaching the SCR and exiting the SCR. Furthermore, the last step includes re-comparing (C2), by the control system (102), the re- calculated CE with the threshold conversion efficiency to detect the abnormality in quality of the urea after refill.
Yet another aspect of the present invention relates to a detecting an abnormality in quality of urea after refill for a Selective Catalytic Reduction (SCR), the system comprising: a control system configured to receive a signal of urea refill; shut-off an engine gas recirculation (EGR), while keeping an amount of diesel exhaust fluid reaching the SCR constant, wherein the shutting-off of the EGR results in receiving of a higher amount of NOX by the SCR than a standard NOX amount; calculate a conversion efficiency (CE) of the SCR based on difference of NOX reaching the SCR and exiting the SCR; compare (C1) the calculated CE with a threshold conversion efficiency; regenerate the SCR based the comparison (C1); re-calculate the conversion efficiency (CE) of the SCR based on difference of NOX reaching the SCR and exiting the SCR; and re-compare (C2) the re- calculated CE with the threshold conversion efficiency to detect the abnormality in quality of the urea after refill.
Yet another aspect of the present invention relates to a method for detecting normality in quality of urea after refill for a Selective Catalytic Reduction (SCR). The method comprising: receiving, by a control system, a signal of urea refill; shutting-off an engine gas recirculation (EGR), on a command of the control system, while keeping an amount of diesel exhaust fluid reaching the SCR constant, wherein the shutting-off of the EGR results in receiving of a higher amount of NOX by the SCR than a standard NOX amount. Next step includes calculating a conversion efficiency (CE) of the SCR, by the control system, based on difference of NOX reaching the SCR and exiting the SCR; comparing (C1), by the control system, the calculated CE with a threshold conversion efficiency, wherein on comparison (C1), subtraction of the calculated CE from the threshold conversion efficiency gives a negative value. Further step includes regenerating the SCR, on the command of the control system, based the comparison (C1) and re-calculating the conversion efficiency (CE) of the SCR, by the control system, based on difference of NOX reaching the SCR and exiting the SCR. Lastly, the next step includes re-comparing (C2), by the control system, the re- calculated CE with the threshold conversion efficiency to detect the normality in quality of the urea after refill.
Yet another aspect of the present invention relates to a system for detecting a normality in quality of urea after refill for a Selective Catalytic Reduction (SCR). The system comprising: a control system configured to receive a signal of urea refill; shut-off an engine gas recirculation (EGR), while keeping an amount of diesel exhaust fluid reaching the SCR constant, wherein the shutting-off of the EGR results in receiving of a higher amount of NOX by the SCR than a standard NOX amount; calculate a conversion efficiency (CE) of the SCR based on difference of NOX reaching the SCR and exiting the SCR; compare (C1) the calculated CE with a threshold conversion efficiency, wherein on comparison (C1), the difference between the calculated CE and the threshold conversion efficiency gives a negative value; regenerate the SCR based the comparison (C1); re-calculate the conversion efficiency (CE) of the SCR based on difference of NOX reaching the SCR and exiting the SCR; and re-compare (C2) the re- calculated CE with the threshold conversion efficiency to detect the normality in quality of the urea after refill.
Other objects, features, and advantages of the present disclosure will become apparent from the following detailed description.

Brief Description of the Drawings
Fig. 1 shows a generic relationship between urea concentration in a Diesel Exhaust Fluid (DEF), NOX emissions and conversion efficiency of a Selective Catalytic Reduction (SCR)
Fig. 2 shows a block diagram of a system for detecting a quality of urea refill for a Selective Catalytic Reduction (SCR) in accordance to all embodiments of the present invention.
Fig. 3 shows a method for detecting a quality of urea refill for a Selective Catalytic Reduction (SCR) in accordance to first embodiment of the present invention.
Fig. 4 shows a method for detecting a quality of urea refill for a Selective Catalytic Reduction (SCR) in accordance to second embodiment of the present invention.
Fig. 5 shows a method for detecting a quality of urea refill for a Selective Catalytic Reduction (SCR) in accordance to third embodiment of the present invention.

Detailed Description of the Invention
As shown in Fig. 2, the system (100) encompasses a control system (102), an internal combustion engine (104), an Exhaust Gas Recirculation (106), a Selective Catalytic Reduction (108), an exhaust pipe (110) and Diesel Exhaust Fluid unit (112).
The system (100) is configured is detect a quality of urea refilled into the Diesel Exhaust Fluid unit (112) in a switched on condition of the internal combustion engine (104). The urea is refilled into the Diesel Exhaust Fluid unit (112) in the form Diesel Exhaust Fluid (DEF) which is combination of urea and water. The system (100) may be configured to detect a normality or an abnormality in the quality. The system (100) may detect the normality in the quality of the urea refilled in an event where the urea amount or urea percentage in the filled Diesel Exhaust Fluid is above a minimum pre-set threshold. In an example, 30-34% of urea in DEF may be considered as a pre-set threshold, and in case the system (100) determines the quality of urea in re-filled DEF less than the pre-set threshold, the system (100) detects the abnormality in the quality of urea refilled. Alternatively, in case the system (100) determines the quality of urea in re-filled DEF more than or equal to the pre-set threshold, the system (100) detects the normality in the quality of urea refilled.
The internal combustion engine (104) may be a conventional diesel engine (104). The internal combustion engine (104) has an exhaust outlet which is connected to the Exhaust Gas Recirculation (106). The Exhaust Gas Recirculation (EGR) (106) may be a conventional EGR. The EGR (106) is further connected to the Selective Catalytic Reduction (108). This creates a passage for an exhaust gas from the EGR (106) the SCR (108).
The SCR (108) may be a conventionally known SCR. The SCR (108) is configured to receive the exhaust gas from the EGR (106). The SCR (108) is also connected to the DEF unit (112). The SCR is configured to receive DEF from the DEF unit (112). Further, the SCR is configured to convert NOX present in the exhaust gas into nitrogen and water. As shown in Fig. 1, with increase in urea concentration, the NOX emission decreases and SCR conversion efficiency increases. In other words, in an event of abnormal urea refill, the efficiency of SCR decreases below a standard SCR efficiency. In another event of normal urea refill, the efficiency of SCR increases above the standard SCR efficiency depending upon the amount of urea in the DEF. Lastly, the SCR (108) is also connected to the exhaust pipe (110). The converted nitrogen, water and other exhaust emissions from the SCR (108) are passed to the exhaust pipe (110).
Further, the system (100), as shown in Fig. 2, encompasses the DEF unit (112). The DEF unit (112) is a tank configured to receive DEF, wherein the DEF is a mixture of urea and water. In an event the amount of urea concentration in the DEF is below the pre-set threshold of urea concentration, the quality of urea refill is considered as abnormal. Alternatively, in an event the amount of urea concentration in the DEF is equal or above the pre-set threshold of urea concentration, the quality of urea refill is considered as normal.
Furthermore, the system (100) also encompasses the control system (102). The control system (102) may be, but not limited to, a microprocessor and a microcontroller. The control system (102) may be an overall Electronic Control Unit of the vehicle or may be a sub-control system for the control system (102). The control system (102) may be connected to the EGR (106), the SCR (108) and the DEF tank (112). The control system (102) is configured to control working of the EGR (106), the SCR (108) and the DEF tank (112). Further, the control system (102) is configured to receive a signal of refill from the DEF tank (112). In an embodiment, the signal of refill from the DEF tank (112) may be received if the amount of refill is above the minimum pre-set refill threshold as measured by a level sensor. In another embodiment, the signal may be received if a camera detects that the amount of refill is above the minimum pre-set refill threshold.
Further, the control system (102) is configured to shut-off the EGR (106), while keeping an amount of DEF reaching the SCR (108) constant. The shutting-off of the EGR (106) results in receiving of a higher amount of NOX by the SCR (108) than a standard NOX amount. The standard NOX amount may be the amount of NOX which is received by the SCR (108) on normal working of the EGR (106). In an embodiment, the higher amount of NOX may be 10-40% greater than the standard NOX amount.
Further, the control system (102) may also be configured to calculate a conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR (108) and exiting the SCR (108). The CE may be calculated as ratio of difference between the NOX reaching the SCR (108) and the NOX exiting the SCR (108) divided by the NOX reaching the SCR (108).
In a first embodiment, the control system (102) may compare (CP) the calculated CE with a threshold conversion efficiency to detect the quality of the urea in refill. The threshold conversion efficiency is the acceptable and pre-set standard efficiency which corresponds to a basic minimum normal quality of urea in the DEF. The control system (102) may detect a normality in quality of refill if the difference in the calculated CE and the threshold conversion efficiency is greater than equal to zero. However, the control system (102) may detect an abnormality in quality of refill if the difference in the calculated CE and the threshold conversion efficiency is negative.
In a second embodiment, the control system (102) may compare (C1) the calculated CE with the threshold conversion efficiency. In an event, wherein on comparison (C1), the difference in the calculated CE and the threshold conversion efficiency is negative, the control system (102) directs the SCR (108) for a regeneration. The regeneration of the SCR (108) is done in order to rule out or remove any possibility of deactivation of the SCR (108). Further, the control system (102) may re-calculate the conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR (108) and exiting the SCR (108). Further, the control system (102) may re-compare (C2) the re- calculated CE with the threshold conversion efficiency. The control system (102) may detect the abnormality in quality of the urea refill if the difference in the re-calculated CE and the threshold conversion efficiency is negative.
In a third embodiment, the control system (102) may compare (C1) the calculated CE with the threshold conversion efficiency. In an event, wherein on comparison (C1), the difference in the calculated CE and the threshold conversion efficiency is negative, the control system (102) directs the SCR (108) for the regeneration. Further, the control system (102) may re-calculate the conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR (108) and exiting the SCR (108). Further, the control system (102) may re-compare (C2) the re- calculated CE with the threshold conversion efficiency. The control system (102) may detect the normality in quality of the urea refill if the difference in the re-calculated CE and the threshold conversion efficiency is greater than equal to zero.
Further, the control system (102) may further notify the detected quality to a user of the internal combustion engine (104) or may stop the working of the internal combustion engine (104). Further, the control system (102) may also direct for further corrective actions to be taken by the user.
In short, the present invention utilizes the fact that with increase in the amount of NOX reaching the SCR (108), the normality in the quality of the urea may be able to achieve higher conversion efficiency compared to the threshold efficiency.
Fig. 3, as per an embodiment, illustrates a method (200) for detecting a quality of urea refill for a Selective Catalytic Reduction (SCR) (108). The method (200) initiates at step 202.
At step 204, a control system (102) receives a signal of urea refill.
At step 206, the control system (102) commands for shutting-off an engine gas recirculation (EGR) (106), while keeping an amount of diesel exhaust fluid reaching the SCR (108) constant, wherein the shutting-off of the EGR (106) results in receiving of a higher amount of NOX by the SCR (108) than a normal NOX amount.
At step 208, the control system (102) calculates a conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR (108) and exiting the SCR (108).
At step 210, the control system (102) compares (CP) the calculated CE with a threshold conversion efficiency.
At step 212, the control system (102) detects the quality of the urea in the refill. The control system (102) may detect a normality in quality of the urea in an event wherein the difference between calculated CE and the threshold conversion efficiency is greater than equal to zero. The control system (102) may detect an abnormality in quality of the urea in an event wherein the difference between calculated CE and the threshold conversion efficiency is negative.
At step 212, the method (200) is completed.
Further, Fig. 3 illustrates another embodiment related to a method (300) for detecting an abnormality in quality of urea refill for a Selective Catalytic Reduction (SCR) (108). The method (300) initiates at step 302.
At step 304, a control system (102) receives a signal of urea refill.
At step 306, the control system (102) the control system (102) commands for shutting-off an engine gas recirculation (EGR) (106), while keeping an amount of diesel exhaust fluid reaching the SCR (108) constant, wherein the shutting-off of the EGR (106) results in receiving of a higher amount of NOX by the SCR (108) than a normal NOX amount.
At step 308, the control system (102) calculates a conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR (108) and exiting the SCR (108).
At step 310, the control system (102) compares (C1) the calculated CE with a threshold conversion efficiency, wherein on comparison, the difference between calculated CE and the threshold conversion efficiency comes out negative.
At step 312, the control system (102) signals for regeneration of the SCR (108).
At step 314, the control system (102) re-calculates a conversion efficiency (CE) of the SCR (108) based on difference of the NOX reaching the SCR (108) and exiting the SCR (108).
At step 316, the control system (102) re-compares (C2) the re-calculated CE the SCR (108) based on difference of the NOX reaching the SCR (108) and exiting the SCR (108), wherein on comparison, the difference between re-calculated CE and the threshold conversion efficiency comes out negative
At step 318, the control system (102) detects the abnormality in quality of the urea refill.
At step 320, the method (300) ends.
Further, Fig. 4 illustrates another embodiment related to a method (400) for detecting a normality in quality of urea refill for a Selective Catalytic Reduction (SCR) (108). The method (400) initiates at step 402.
At step 404, a control system (102) receives a signal of urea refill.
At step 406, the control system (102 the control system (102) commands for shutting-off an engine gas recirculation (EGR) (106), while keeping an amount of diesel exhaust fluid reaching the SCR (108) constant, wherein the shutting-off of the EGR (106) results in receiving of a higher amount of NOX by the SCR (108) than a normal NOX amount.
At step 408, the control system (102) calculates a conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR (108) and exiting the SCR (108).
At step 410, the control system (102) compares (C1) the calculated CE with a threshold conversion efficiency, wherein difference between the calculated CE with the threshold conversion efficiency is negative.
At step 412, the control system (102) signals for regeneration of the SCR (108).
At step 414, the control system (102) re-calculates a conversion efficiency (CE) of the SCR (108) based on difference of the NOX reaching the SCR (108) and exiting the SCR (108).
At step 416, the control system (102) re-compares (C2) the re-calculated CE the SCR (108) based on difference of the NOX reaching the SCR (108) and exiting the SCR (108), wherein on re- comparison, the difference between re- calculated CE and the threshold conversion efficiency comes greater than or equal to zero.
At step 418, the control system (102) detects the normality in quality of the urea refill.
At step 420, the method (400) ends.
Subsequently, the control system (102) may further notify the detected quality to a user of the internal combustion engine (104) or may stop the working of the internal combustion engine (104). Further, the control system (102) may also direct for further corrective actions to be taken by the user.
Therefore, the present invention provides system and method of detecting quality of urea after refill for the SCR.
Although, the present invention has been described in considerable detail with reference to certain preferred embodiments and examples thereof, other embodiments and equivalents are possible. Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with functional and procedural details, the invention is illustrative only, and changes may be made in detail, especially in terms of the procedural steps within the principles of the invention to the full extent indicated by the broad general meaning of the terms. Thus, various modifications are possible of the presently disclosed system and process without deviating from the intended scope and spirit of the present invention. Accordingly, in one embodiment, such modifications of the presently disclosed system are included in the scope of the present invention. , Claims:We Claim:
1. A method (200) for detecting a quality of urea after refill for a Selective Catalytic Reduction (SCR) (108), the method comprising:
- receiving, by a control system (102), a signal of urea refill;
- shutting-off an engine gas recirculation (EGR) (106), on a command of the control system (102), while keeping an amount of diesel exhaust fluid reaching the SCR (108) constant, wherein the shutting-off of the EGR (106) results in receiving of a higher amount of NOX by the SCR (108) than a standard NOX amount;
- calculating a conversion efficiency (CE) of the SCR (108), by the control system (102), based on difference of NOX reaching the SCR (108) and exiting the SCR (108); and
- comparing (CP), by the control system (102), the calculated CE with a threshold conversion efficiency to detect the quality of the urea refill.
2. The method (200) as claimed in claim 1, wherein the quality of urea refill is any one of abnormal and normal.
3. A system (100) for detecting a quality of urea after refill for a Selective Catalytic Reduction (SCR) (108), the system (100) comprising:
- a control system (102) configured to
receive a signal of urea refill;
shut-off an engine gas recirculation (EGR) (106), while keeping an amount of diesel exhaust fluid reaching the SCR (108) constant, wherein the shutting-off of the EGR (106) results in receiving of a higher amount of NOX by the SCR (108) than a standard NOX amount;
calculate a conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR (108) and exiting the SCR (108); and
compare (CP) the calculated CE with a threshold conversion efficiency to detect any one of the abnormality and the normality in quality of the urea refill.
4. The system (100) as claimed in claim 3, wherein the quality of urea refill is any one of abnormal and normal.

5. A method (300) for detecting an abnormality in quality of urea refill for a Selective Catalytic Reduction (SCR) (108), the method comprising:
- receiving, by a control system (102), a signal of urea refill;
- shutting-off an engine gas recirculation (EGR) (106), on a command of the control system (102), while keeping an amount of diesel exhaust fluid reaching the SCR (108) constant, wherein the shutting-off of the EGR (106) results in receiving of a higher amount of NOX by the SCR (108) than a standard NOX amount;
- calculating a conversion efficiency (CE) of the SCR (108), by the control system, based on difference of NOX reaching the SCR (108) and exiting the SCR (108);
- comparing (C1), by the control system (102), the calculated CE with a threshold conversion efficiency;
- regenerating the SCR (108), on the command of the control system (102), based the comparison (C1);
- re-calculating the conversion efficiency (CE) of the SCR (108), by the control system (102), based on difference of NOX reaching the SCR (108) and exiting the SCR (108); and
- re-comparing (C2), by the control system (102), the re- calculated CE with the threshold conversion efficiency to detect the abnormality in quality of the urea refill.
6. A system (100) for detecting an abnormality in quality of urea after refill for a Selective Catalytic Reduction (SCR) (108), the system comprising:
- a control system (102) configured to
receive a signal of urea refill;
shut-off an engine gas recirculation (EGR) (106), while keeping an amount of diesel exhaust fluid reaching the SCR (108) constant, wherein the shutting-off of the EGR (106) results in receiving of a higher amount of NOX by the SCR (108) than a standard NOX amount;
calculate a conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR and exiting the SCR;
compare (C1) the calculated CE with a threshold conversion efficiency;
regenerate the SCR (108) based the comparison (C1);
re-calculate the conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR (108) and exiting the SCR (108); and
re-compare (C2) the re- calculated CE with the threshold conversion efficiency to detect the abnormality in quality of the urea refill.
7. A method (400) for detecting a normality in quality of urea after refill for a Selective Catalytic Reduction (SCR) (108), the method comprising:
- receiving, by a control system (102), a signal of urea refill;
- shutting-off an engine gas recirculation (EGR) (106), on a command of the control system (102), while keeping an amount of diesel exhaust fluid reaching the SCR (108) constant, wherein the shutting-off of the EGR (106) results in receiving of a higher amount of NOX by the SCR (108) than a standard NOX amount;
- calculating a conversion efficiency (CE) of the SCR (108), by the control system (102), based on difference of NOX reaching the SCR (108) and exiting the SCR (108);
- comparing (C1), by the control system (102), the calculated CE with a threshold conversion efficiency, wherein on comparison (C1), subtraction of the calculated CE from the threshold conversion efficiency gives a negative value;
- regenerating the SCR (108), on the command of the control system (102), based the comparison (C1);
- re-calculating the conversion efficiency (CE) of the SCR (108), by the control system (102), based on difference of NOX reaching the SCR (108) and exiting the SCR (108); and
- re-comparing (C2), by the control system (102), the re- calculated CE with the threshold conversion efficiency to detect the normality in quality of the urea refill.
8. A system (100) for detecting a normality in quality of urea after refill for a Selective Catalytic Reduction (SCR) (108), the system comprising:
- a control system (102) configured to
receive a signal of urea refill;
shut-off an engine gas recirculation (EGR) (106), while keeping an amount of diesel exhaust fluid reaching the SCR (108) constant, wherein the shutting-off of the EGR (106) results in receiving of a higher amount of NOX by the SCR (108) than a standard NOX amount;
calculate a conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR (108) and exiting the SCR (108);
compare (C1) the calculated CE with a threshold conversion efficiency), wherein on comparison (C1), the difference between the calculated CE and the threshold conversion efficiency gives a negative value;
regenerate the SCR (108) based the comparison (C1);
re-calculate the conversion efficiency (CE) of the SCR (108) based on difference of NOX reaching the SCR (108) and exiting the SCR (108); and
re-compare (C2) the re- calculated CE with the threshold conversion efficiency to detect the normality in quality of the urea refill.