Patent Description:
Conventional exhaust aftertreatment systems for, e.g., diesel engines often use a catalytic reduction arrangement to convert certain harmful exhaust components into less harmful substances. In one example of the process, a reducing agent is injected into an engine exhaust and hydrolyzes into ammonia, which flows into the catalyst. A chemical reaction involving the ammonia and the unwanted exhaust components within the catalytic reduction arrangement substrate reduces the unwanted exhaust component into Nitrogen gas and water. For the emission control to be robust in a wide range of driving conditions, the level of ammonia buffer stored in the catalytic reduction arrangement should preferably be controlled. In particular, should the ammonia buffer be too low, there is a risk of having too small amount of conversion of harmful exhaust, and should the ammonia buffer be too high, there is a risk that ammonia will be released and cause undesirable exhaust of harmful exhaust and ammonia emissions.

A conventional solution is to use a model of the catalytic reduction arrangement to decide setpoints on how to control the ammonia buffer. However, it has been realized that such model has deficiencies, in particular in terms of unexpected changes of ammonia buffer capacity when the catalytic reduction arrangement is somewhat degraded.

<CIT> relates to a method for operating an SCR catalytic converter for the aftertreatment of exhaust gases from an internal combustion engine, in which a reducing agent is metered in to reduce nitrogen oxides (NOx) in the exhaust gas and the required amount of the reducing agent to be metered is calculated on the basis of a model predeterminable threshold between a measured NOx sensor value NOxSens downstream of the SCR catalytic converter and a modelled NOx value NOxEst downstream of the SCR catalytic converter, a discontinuous adaptation is carried out by lowering the fill level in response to a detected underdosing or overdosing of the reducing agent. For further continuous adaptation of the dosage of the reducing agent, NOxSens is compared with NOxEst and the dosage of the reducing agent is reduced for NOxSens <NOxEst and the dosage is increased for NOxSens > NOxEst.

Further, <CIT> relates to a dosing control system for a vehicle and includes an adaption triggering module, a dosing management module, and an adaption ending module.

According to a first aspect of the inventive concept, there is provided a method of operating a reducing agent injector, the reducing agent injector being configured to inject a reducing agent into a catalytic reduction arrangement arranged in downstream fluid communication with an internal combustion engine of a vehicle at a pre-set mass flow rate obtained by a predefined injection model, the method comprising determining a reference level of toxic substances exhausted from the catalytic reduction arrangement when injecting reducing agent at the pre-set mass flow rate; controlling the reducing agent injector to inject reducing agent at a first mass flow rate, the first mass flow rate being different from the pre-set mass flow rate; determining a first level of toxic substances exhausted from the catalytic reduction arrangement after injecting reducing agent at the first mass flow rate; determining which one of the reference level of toxic substances and the first level of toxic substances being a lowest level of toxic substances; updating the pre-set mass flow rate of the predefined injection model to an updated pre-set mass flow rate as the mass flow rate causing the catalytic reduction arrangement to exhaust the lowest level of toxic substances; and controlling the reducing agent injector to inject reducing agent at the updated pre-set mass flow rate.

The reducing agent should be construed as reduction liquid providing a chemical composition with the material of the catalytic reduction arrangement that will convert the environmentally harmful exhaust gas from the internal combustion engine into less harmful substances. The reducing agent may, according to a non-limiting example, be urea which is particularly suitable for reducing NOx-gases.

The first aspect of the inventive concept may seek to compensate for unexpected changes in hardware of a catalytic reduction arrangement, in particular for a catalytic reduction arrangement which is somewhat degraded. In particular, when a change in the mass flow rate results in a reduction in the level of toxic substances exhausted from the catalytic reduction arrangement compared to the level of toxic substances exhausted when reducing agent was injected at the pre-set mass flow rate, an indication is given that the changed mass flow rate should be used. The pre-set mass flow rate may thus be seen as a nominal mass flow rate based on the injection model. However, should the change in mass flow rate result in an increase in the level of toxic substances exhausted from the catalytic reduction arrangement, the pre-set mass flow rate should be kept.

A technical benefit may thus include that a catalytic reduction arrangement can be operated efficiently even when being aged and the buffer capacity has been degraded. Further, another technical benefit may include that the above-described method may assist to handle component deviations from production. For example, when a substrate of the catalytic converter arrangement differs from another one when it comes to an actual buffer capacity.

In some examples, the method may further comprise determining a first operating state of the catalytic reduction arrangement when determining the reference level of toxic substances, the first operating state being at least one of a reference temperature level of the catalytic reduction arrangement and an exhaust gas flow velocity through the catalytic reduction arrangement; and controlling the reducing agent injector to inject reducing agent at the first mass flow rate when the catalytic reduction arrangement assumes the first operating state. The comparison of the reference level of toxic substances and the first level of toxic substances is thus made at substantially the same operating condition and it may hereby be assured that the updated pre-set mass flow rate is determined correctly.

In some examples, the first mass flow rate may be an increased mass flow rate compared to the pre-set mass flow rate, the method may further comprise controlling the reducing agent injector to inject reducing agent at a second mass flow rate, the second mass flow rate being a decreased mass flow rate compared to the pre-set mass flow rate; determining a second level of toxic substances exhausted from the catalytic reduction arrangement after injecting reducing agent at the second mass flow rate; and determining which one of the reference level of toxic substances, the first level of toxic substances and the second level of toxic substances being the lowest level of toxic substances.

An iterative process may hereby be adopted, whereafter the lowest level of toxic substances is determined. By both increasing the mass flow rate as well as decreasing the mass flow rate, it may be even further assured that an optimized updated pre-set mass flow rate is selected. Accordingly, and in some examples, the method may further comprise selecting the second mass flow rate as the updated pre-set mass flow rate when the reference level of toxic substances, the first level of toxic substances and the second level of toxic substances are within a predetermined range.

In some examples, the reducing agent may be injected at the second mass flow rate when the catalytic reduction arrangement assumes the first operating state. The second level of toxic substances may advantageously be determined at substantially the same circumstances as when determining the reference level of toxic substances, as well as when determining the first level of toxic substances.

In some examples, the pre-set mass flow rate of the predefined injection model may be updated for a plurality of temperature levels of the catalytic reduction arrangement. Thus, each temperature level of the catalytic reduction arrangement may be provided with an updated pre-set mass flow rate. A technical advantage may be that the operational functionality of the catalytic reduction arrangement can be optimized for substantially all temperatures.

In some examples, the pre-set mass flow rate of the predefined injection model may be updated sequentially for the plurality of temperature levels of the catalytic reduction arrangement.

In some examples, the method may further comprise determining a time period since installation of the catalytic reduction arrangement; and transmitting the updated pre-set mass flow rate and the time period to a control server station. The process of determining the optimum mass flow rate may hereby be omitted for other vehicles in a fleet, since it can be assumed that a catalytic reduction arrangement for another vehicle will, more or less, assume a similar condition when aged in a similar manner.

In some examples, the catalytic reduction arrangement may be a selective catalytic reduction arrangement. When the catalytic reduction arrangement is a selective catalytic reduction arrangement, the reducing agent is preferably urea.

According to a second aspect of the inventive concept, there is provided an injection system, comprising a reducing agent injector configured to inject a reducing agent into a catalytic reduction arrangement arranged in downstream fluid communication with an internal combustion engine of a vehicle, and processing circuitry operatively coupled to the reducing agent injector, the processing circuitry comprises an injection manager operative to instruct the reducing agent injector to inject reducing agent at a pre-set mass flow rate, wherein the processing circuitry is configured to determine a reference level of toxic substances exhausted from the catalytic reduction arrangement when injecting reducing agent at the pre-set mass flow rate; transmit a message to the reducing agent injector, the message representing instructions to control the reducing agent injector to inject reducing agent at a first mass flow rate, the first mass flow rate being different from the pre-set mass flow rate; determine a first level of toxic substances exhausted from the catalytic reduction arrangement after injecting reducing agent at the first mass flow rate; determine which one of the reference level of toxic substances and the first level of toxic substances being a lowest level of toxic substances; update the pre-set mass flow rate of the predefined injection model to an updated pre-set mass flow rate as the mass flow rate causing the catalytic reduction arrangement to exhaust the lowest level of toxic substances; and transmit a message to the reducing agent injector, the message representing instructions to control the reducing agent injector to inject reducing agent at the updated pre-set mass flow rate.

In some examples, the injection system may further comprise a sensor configured to detect the level of toxic substances exhausted from the catalytic reduction arrangement. A sensor may advantageously sense the level of toxic substances exhausted from the catalytic reduction arrangement and transmit data to the processing circuitry for rapid action. In some examples, the sensor may be a NOx sensor.

Further effects and features of the second aspect are largely analogous to those described above in relation to the first aspect.

According to a third aspect of the inventive concept, there is provided a vehicle comprising an internal combustion engine, a catalytic reduction arrangement arranged in downstream fluid communication with the internal combustion engine, and an injection system according to any one of the embodiments described above in relation to the second aspect.

According to a fourth aspect of the inventive concept, there is provided a computer program product comprising program code for performing, when executed by the processing circuitry, the method of any of the examples described above in relation to the first aspect.

According to a fifth aspect of the inventive concept, there is provided a control system comprising one or more control units configured to perform the method according to any of the examples described above in relation to the first aspect.

According to a sixth aspect of the inventive concept, there is provided a non-transitory computer-readable storage medium comprising instructions, which when executed by a processing circuitry, cause the processing circuitry to perform the method of any of the examples described above in relation to the first aspect.

Effects and features of the third, fourth, fifth and sixth aspects are largely analogous to those described above in relation to the first and second aspects.

Additional features and advantages are disclosed in the following description, claims, and drawings, and in part will be readily apparent therefrom to those skilled in the art or recognized by practicing the inventive concept as described herein.

With reference to the appended drawings, below follows a more detailed description of aspects of the inventive concept cited as examples.

Aspects set forth below represent the necessary information to enable those skilled in the art to practice the inventive concept.

The inventive concept described in the following with reference to the drawings may seek to solve the problem of unexpected changes in hardware of catalytic reduction arrangements, in particular for catalytic reduction arrangements which are somewhat degraded. An overall technical advantage of the below disclosure may thus be that the catalytic reduction arrangements can be efficiently operable for a longer duration of time, and that unexpected changes can be handled without the need of replacement or maintenance of parts.

With reference to <FIG>, there is depicted a vehicle <NUM> in the form of a truck. The vehicle <NUM> comprises a traction motor <NUM>. The traction motor <NUM> is preferably an internal combustion engine and will in the following be referred to as such. The internal combustion engine <NUM> is operable to propel at least one pair of wheels <NUM> of the vehicle <NUM>. The vehicle <NUM> further comprises an aftertreatment system <NUM> arranged in downstream fluid communication with the internal combustion engine <NUM>. The vehicle <NUM> in <FIG> also comprises a control unit <NUM>. The control unit <NUM> comprises processing circuitry (depicted in further detail in <FIG>).

The processing circuitry is operatively coupled to various parts of the aftertreatment system <NUM>, as will be evident below.

In order to describe the aftertreatment system <NUM> in further detail, reference is made to <FIG> which is a schematic illustration of an aftertreatment system <NUM> according to one example. The internal combustion engine <NUM> is also depicted in <FIG>, although not forming part of the aftertreatment system <NUM>. As can be seen in <FIG>, the aftertreatment system <NUM> is arranged in downstream fluid communication with the internal combustion engine <NUM> via an exhaust conduit <NUM>. Hence, exhaust gas generated by the internal combustion engine <NUM> during combustion is directed through the exhaust conduit <NUM> and into the aftertreatment system <NUM>. An outlet conduit <NUM> is also connected to the aftertreatment system <NUM> through which the exhaust gas is directed after being treated in the aftertreatment system <NUM>.

The aftertreatment system <NUM> comprises a catalytic reduction arrangement <NUM>. The catalytic reduction arrangement <NUM> is merely schematically illustrated and is configured to convert environmentally harmful exhaust gas from the internal combustion engine <NUM> into less harmful substances which are exhausted to the ambient environment via the outlet conduit <NUM>. According to an example, the catalytic reduction arrangement <NUM> may be a selective catalytic reduction arrangement.

Further, the aftertreatment system <NUM> comprises an injection system <NUM>. The injection system <NUM> comprises a reducing agent injector <NUM> configured to inject a reducing agent <NUM> into the catalytic reduction arrangement <NUM>. When injecting reducing agent <NUM>, the reducing agent hydrolyzes to ammonia which forms an ammonia buffer. A chemical reaction involving the ammonia and unwanted exhaust components reduces the exhaust components into less harmful substances, such as e.g. Nitrogen gas and water. The chemical reaction thus converts the environmentally harmful exhaust gas from the internal combustion engine into less harmful substances. The reducing agent may, according to a non-limiting example, be urea which is particularly suitable for reducing NOx-gases. The injection system <NUM> also comprises a reducing agent reservoir <NUM>. The reducing agent reservoir <NUM> may, for example, be a tank configured to contain the reducing agent. The reducing agent injector <NUM> is thus arranged in downstream fluid communication with the reducing agent reservoir <NUM> and hence receives reducing agent from the reducing agent reservoir <NUM> for injecting the reducing agent <NUM> into the catalytic reduction arrangement <NUM>.

The exemplified aftertreatment system <NUM> depicted in <FIG> also comprises a sensor <NUM>. The sensor <NUM> is configured to detect a level of toxic substances exhausted from the catalytic reduction arrangement <NUM>. The sensor <NUM> is thus preferably positioned downstream the catalytic reduction arrangement <NUM>. In <FIG>, the sensor <NUM> is depicted as being arranged in the outlet conduit <NUM>, but could also be connected to the catalytic reduction arrangement <NUM> at a downstream side thereof. According to an example, the sensor <NUM> may preferably be a NOx sensor configured to detect the level of NOx in the exhaust flow form the catalytic reduction arrangement <NUM>.

As is also illustrated in <FIG>, the control unit <NUM> is connected to the reducing agent injector <NUM> as well as to the sensor <NUM>. The control unit <NUM> is thus configured to receive data indicative of the level of toxic substances from the sensor <NUM> and to control operation of the reducing agent injector <NUM>. In particular, the control unit <NUM> comprises processing circuitry as described above. The processing circuitry comprises an injection manager <NUM>. The injection manager <NUM> is operative to instruct the reducing agent injector <NUM> to inject reducing agent at a mass flow rate determined by the processing circuitry.

In order to describe operation of the present inventive concept, reference is now made to <FIG> are graphs illustrating a relationship between reducing agent buffer and temperature according to examples. In particular, the vertical axes <NUM> represent an expected buffer of reducing agent <NUM> in the catalytic reduction arrangement <NUM>, while the horizontal axes <NUM> represent a temperature level of the catalytic reduction arrangement <NUM>. The solid line <NUM> <FIG> is intended to represent the relationship between the reducing agent buffer in the catalytic reduction arrangement <NUM> for various temperature levels before initiating operation of the inventive concept disclosed herein. In the <FIG> example, reducing agent <NUM> is injected into the catalytic reduction arrangement <NUM> at a pre-set mass flow rate, wherein the pre-set mass flow rate may be different for each of the plurality of temperature levels. As can be seen, the expected buffer of reducing agent is expected to be reduced when the temperature of the catalytic reduction arrangement <NUM> increases. Thus, for a first temperature level <NUM>, reducing agent <NUM> is injected at a first pre-set mass flow rate forming a first expected reducing agent buffer <NUM> for the first temperature level <NUM> in the catalytic reduction arrangement <NUM>. In a similar vein, for a second temperature level <NUM>, reducing agent <NUM> is injected at a second pre-set mass flow rate forming a second expected reducing agent buffer for the second temperature level <NUM> in the catalytic reduction arrangement <NUM>. A third <NUM>, a fourth <NUM>, and a fifth <NUM> reducing agent buffer is expected when injecting reducing agent <NUM> at a third, a fourth, and a fifth pre-set mass flow rate for a third <NUM>, a fourth <NUM>, and a fifth <NUM> temperature level, respectively, to generate the graph of <FIG>.

The following will mainly, and initially, describe the operation of the present inventive concept with reference to the first temperature level <NUM> of the catalytic reduction arrangement <NUM>. During operation, when the temperature of the catalytic reduction arrangement <NUM> is at the first temperature level <NUM>, a reference level of toxic substances exhausted from the catalytic reduction arrangement <NUM> when injecting reducing agent <NUM> at the first pre-set mass flow rate is determined. The pre-set mass flow rate is preferably injected based on a predefined injection model. In particular, the sensor <NUM> preferably detects the reference level of toxic substances and transmits data indicative of the level of toxic substances to the processing circuitry.

For a similar operating condition of the catalytic reduction arrangement <NUM>, i.e., when the temperature of the catalytic reduction arrangement <NUM> is at the first temperature level <NUM>, and optionally also when an exhaust gas flow velocity is similar to when detecting the reference level of toxic substances, the injector manager <NUM> transmits a message to the reducing agent injector <NUM> to inject reducing agent <NUM> at a first mass flow rate. The first mass flow rate is different from the pre-set mass flow rate. In the present example, the first mass flow rate is higher than the pre-set mass flow rate, thereby providing a first higher <NUM> expected reducing agent buffer in the catalytic reduction arrangement <NUM>. When the reducing agent injector <NUM> has injected the reducing agent <NUM> at the first mass flow rate, a first level of toxic substances exhausted from the catalytic reduction arrangement is determined, preferably by the sensor <NUM>. The processing circuitry determines which one of the reference level of toxic substances and the first level of toxic substances being a lowest level of toxic substances, i.e. the processing circuitry compares the reference level of toxic substances and the first level of toxic substances with each other to determine which one of the mass flow rates generating the lowest level of toxic substances.

Thereafter, the processing circuitry updates the pre-set mass flow rate of the predefined injection model to an updated pre-set mass flow rate. The updated pre-set mass flow rate is selected as the one of the pre-set mass flow rate and the first mass flow rate that generates the lowest levels of toxic substances, i.e. the mass flow rate causing the catalytic reduction arrangement <NUM> to exhaust the lowest level of toxic substances. The injection manager thereafter transmits a message to the reducing agent with instructions to inject reducing agent <NUM> at the updated pre-set mass flow rate for the first temperature level <NUM>.

As an example, and as an intermediate step, the injection manager <NUM> may transmit data to the reducing agent injector <NUM> to inject reducing agent at a second mass flow rate, wherein the second mass flow rate is a decreased/reduced mass flow rate compared to the pre-set mass flow rate. The second mass flow rate thus provides a first lower <NUM> expected reducing agent buffer in the catalytic reduction arrangement <NUM>. The second mass flow rate is thus lower than the pre-set mass flow rate. In a similar vein as described above, when the reducing agent injector <NUM> has injected the reducing agent <NUM> at the second, lower mass flow rate, a second level of toxic substances exhausted from the catalytic reduction arrangement is determined, preferably by the sensor <NUM>.

Hereby, the level of toxic substances exhausted from the catalytic reducing arrangement <NUM> can be determined for a first mass flow rate, the second mass flow rate, and for the pre-set mass flow rate, whereby the mass flow rate providing the lowest levels of toxic substances is selected as the updated pre-set mass flow rate. In the present example illustrated in <FIG>, the second mass flow rate is selected as the updated pre-set mass flow rate for the first temperature, since the second mass flow rate turned out to cause the catalytic reduction arrangement <NUM> to reduce the level of toxic substances.

The operating steps described above in relation to the first temperature level <NUM> is thereafter performed, preferably sequentially, for the second <NUM>, third <NUM>, fourth <NUM> and fifth <NUM> temperature levels, which results in an updated relationship between expected reducing agent buffer in the catalytic reduction arrangement <NUM> for various temperature levels, which is indicated with the dashed line <NUM>.

In the exemplified illustration in <FIG>, the mass flow rate is reduced for the first <NUM>, second <NUM> and third <NUM> temperature levels, while the mass flow rate is increased for the fourth <NUM> and fifth <NUM> temperature levels. In other words, the mass flow rate for the different temperature is selected such that a second lower <NUM> expected reducing agent buffer is provided for the second temperature level <NUM>, a third lower <NUM> expected reducing agent buffer is provided for the third temperature level <NUM>, a fourth higher <NUM> is provided for the fourth temperature level <NUM>, and a fifth higher <NUM> expected reducing agent buffer is provided for the fifth temperature level <NUM>. The pre-set mass flow rate of the predefined injection model is hereby updated for each temperature level as indicated in <FIG>.

It should however be readily understood that the illustration in <FIG> merely serves as one example. For example, the updated mass flow rate at, e.g., one or more of the first <NUM>, second <NUM> and third <NUM> temperature levels could be increased compared to the pre-set mass flow rate if the level of toxic substances was reduced for such increase. Similarly, the mass flow rate at one or both of the fourth <NUM> and fifth <NUM> temperature levels could be reduced compared to the pre-set mass flow rate if the level of toxic substances was reduced for such reduction. Also, further or less temperature levels may be used for the evaluation.

In order to reduce the consumption of reducing agent, the second mass flow rate is preferably selected as the updated pre-set mass flow rate when the reference level of toxic substances, the first level of toxic substances and the second level of toxic substances are within a predetermined range. Thus, if no substantial difference in toxic substances is detected for the different mass flow rates, the lowest mass flow rate can be selected.

Reference is now made to <FIG> which is a flow chart of a method of operating the above described reducing agent injector <NUM>. As described above, a reference level of toxic substances exhausted from the catalytic reduction arrangement <NUM> is determined S1 when injecting reducing agent at the pre-set mass flow rate. The reducing agent injector <NUM> is controlled S2 to inject reducing agent at a first mass flow rate, the first mass flow rate being different from the pre-set mass flow rate. A first level of toxic substances exhausted from the catalytic reduction arrangement <NUM> is determined S3 after injecting reducing agent <NUM> at the first mass flow rate. It is thereafter determined S4 which one of the reference level of toxic substances and the first level of toxic substances being a lowest level of toxic substances. The pre-set mass flow rate of the predefined injection model is then updated S5 to an updated pre-set mass flow rate as the mass flow rate causing the catalytic reduction arrangement <NUM> to exhaust the lowest level of toxic substances. The reducing agent injector <NUM> is then controlled S6 to inject reducing agent at the updated pre-set mass flow rate.

Turning now to <FIG>, which is a schematic diagram of an exemplary computer system for implementing examples disclosed herein, according to one example.

<FIG> is a schematic diagram of a computer system <NUM> for implementing examples disclosed herein. The computer system <NUM> is adapted to execute instructions from a computer-readable medium to perform these and/or any of the functions or processing described herein. The computer system <NUM> may be connected (e.g., networked) to other machines in a LAN, an intranet, an extranet, or the Internet. While only a single device is illustrated, the computer system <NUM> may include any collection of devices that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. Accordingly, any reference in the disclosure and/or claims to a computer system, computing system, computer device, computing device, control system, control unit, electronic control unit (ECU), processing circuitry, etc., includes reference to one or more such devices to individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. For example, control system may include a single control unit or a plurality of control units connected or otherwise communicatively coupled to each other, such that any performed function may be distributed between the control units as desired. Further, such devices may communicate with each other or other devices by various system architectures, such as directly or via a Controller Area Network (CAN) bus, etc..

The computer system <NUM> may comprise at least one computing device or electronic device capable of including firmware, hardware, and/or executing software instructions to implement the functionality described herein. The computer system <NUM> may include a processing circuitry <NUM> (may also be referred to as a control unit), a memory <NUM>, and a system bus <NUM>. The computer system <NUM> may include at least one computing device having the processing circuitry <NUM>. The system bus <NUM> provides an interface for system components including, but not limited to, the memory <NUM> and the processing circuitry <NUM>. The processing circuitry <NUM> may include any number of hardware components for conducting data or signal processing or for executing computer code stored in memory <NUM>. The processing circuitry <NUM> (e.g., control unit) may, for example, include a general-purpose processor, an application specific processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a circuit containing processing components, a group of distributed processing components, a group of distributed computers configured for processing, or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. The processing circuitry may further include computer executable code that controls operation of the programmable device.

The system bus <NUM> may be any of several types of bus structures that may further interconnect to a memory bus (with or without a memory controller), a peripheral bus, and/or a local bus using any of a variety of bus architectures. The memory <NUM> may be one or more devices for storing data and/or computer code for completing or facilitating methods described herein. The memory <NUM> may include database components, object code components, script components, or other types of information structure for supporting the various activities herein. Any distributed or local memory device may be utilized with the systems and methods of this description. The memory <NUM> may be communicably connected to the processing circuitry <NUM> (e.g., via a circuit or any other wired, wireless, or network connection) and may include computer code for executing one or more processes described herein. The memory <NUM> may include non-volatile memory <NUM> (e.g., read-only memory (ROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.), and volatile memory <NUM> (e.g., random-access memory (RAM)), or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a computer or other machine with a processing circuitry <NUM>. A basic input/output system (BIOS) <NUM> may be stored in the non-volatile memory <NUM> and can include the basic routines that help to transfer information between elements within the computer system <NUM>.

A number of modules can be implemented as software and/or hard-coded in circuitry to implement the functionality described herein in whole or in part. The modules may be stored in the storage device <NUM> and/or in the volatile memory <NUM>, which may include an operating system <NUM> and/or one or more program modules <NUM>. All or a portion of the examples disclosed herein may be implemented as a computer program product <NUM> stored on a transitory or non-transitory computer-usable or computer-readable storage medium (e.g., single medium or multiple media), such as the storage device <NUM>, which includes complex programming instructions (e.g., complex computer-readable program code) to cause the processing circuitry <NUM> to carry out the steps described herein. Thus, the computer-readable program code can comprise software instructions for implementing the functionality of the examples described herein when executed by the processing circuitry <NUM>. The processing circuitry <NUM> may serve as a controller or control system for the computer system <NUM> that is to implement the functionality described herein.

The computer system <NUM> also may include an input device interface <NUM> (e.g., input device interface and/or output device interface). The input device interface <NUM> may be configured to receive input and selections to be communicated to the computer system <NUM> when executing instructions, such as from a keyboard, mouse, touch-sensitive surface, etc. Such input devices may be connected to the processing circuitry <NUM> through the input device interface <NUM> coupled to the system bus <NUM> but can be connected through other interfaces such as a parallel port, an Institute of Electrical and Electronic Engineers (IEEE) <NUM> serial port, a Universal Serial Bus (USB) port, an IR interface, and the like. The computer system <NUM> may include an output device interface <NUM> configured to forward output, such as to a display, a video display unit (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)). The computer system <NUM> may also include a communications interface <NUM> suitable for communicating with a network as appropriate or desired.

Claim 1:
A method of operating a reducing agent injector (<NUM>), the reducing agent injector being configured to inject a reducing agent into a catalytic reduction arrangement (<NUM>) arranged in downstream fluid communication with an internal combustion engine (<NUM>) of a vehicle (<NUM>) at a pre-set mass flow rate obtained by a predefined injection model (<NUM>),
the method comprising:
- determining (S1) a reference level of toxic substances exhausted from the catalytic reduction arrangement (<NUM>) when injecting reducing agent at the pre-set mass flow rate;
- controlling (S2) the reducing agent injector (<NUM>) to inject reducing agent at a first mass flow rate, the first mass flow rate being different from the pre-set mass flow rate;
- determining (S3) a first level of toxic substances exhausted from the catalytic reduction arrangement (<NUM>) after injecting reducing agent at the first mass flow rate;
- determining (S4) which one of the reference level of toxic substances and the first level of toxic substances being a lowest level of toxic substances;
- updating (S5) the pre-set mass flow rate of the predefined injection model to an updated pre-set mass flow rate as the mass flow rate causing the catalytic reduction arrangement (<NUM>) to exhaust the lowest level of toxic substances; and
- controlling (S6) the reducing agent injector (<NUM>) to inject reducing agent at the updated pre-set mass flow rate.