Diesel exhaust fluid electronics module

Abstract

A diesel exhaust fluid (DEF) electronics module for a DEF system of a diesel internal combustion engine. The DEF electronics module comprises an electronic component of the DEF system provided within

Description

Field of the disclosure The present disclosure relates to diesel internal combustion engines. In particular, the present disclosure relates to the treatment of exhaust gases from a diesel internal combustion engine. Background An aftertreatment system for a diesel internal combustion engine typically includes a selective catalytic reduction (SCR). SCR may be provided as part of an aftertreatment system to reduce the amount of NOX present in the exhaust gasses. An SCR system utilises an aqueous urea solution (often referred to as Diesel Exhaust Fluid or DEF). The DEF is injected into the exhaust gas, where the heat from the exhaust gas causes the urea to decompose into ammonia. The ammonia then reacts at the SCR to reduce the NOX to nitrogen and water. DEF for use with an SCR is typically stored in a tank. DEF may be pumped from the tank to the aftertreatment system when the engine is running. DEF stored in the DEF tank may decompose into ammonia gas. In particular, urea decomposition within the DEF tank may become more pronounced as the DEF temperature increases beyond ambient conditions. Summary According to a first aspect of the disclosure, a diesel exhaust fluid (DEF) electronics module for a DEF system of a diesel internal combustion engine is provided. The DEF electronics module comprises: an electronic component of the DEF system; a housing for the electronic component, wherein the electronic component is provided within the housing; and a contaminant indicator provided within the housing, the contaminant indicator being configured to record the presence of a contaminant within the housing. The present inventors have realised that contaminants such as ammonia, urea, water, fuel, coolant and their derivatives, if present in a DEF system, have the capability to unintentionally cause changes in the operation of one or more electronic components of a DEF system. For example, exposure to a contaminant may cause one or more electronic components to become non-operational, for example due to corrosion of protective barriers, short circuiting and the like. Some contaminants, such as fuel or coolant may also cause damage to sensors or seals which may unintentionally cause changes in the operation of the DEF electronics module. While the electronics module of the first aspect provides a housing for the electronic component which provides some insulation from contaminants for the electronic component, the present inventors have also realised that some contaminants (e.g. ammonia) may permeate through the housing during use of the DEF system. As such, it may be challenging to prevent contaminants reaching an electronic component of a DEF electronics module. If a contaminant does reach an electronic component, the present inventors have realised that it is challenging to diagnose that a contaminant has caused a change in the operation of an electronic component. For example, it may be challenging to replicate the issue on a test bench, since the process may be reversable. Consequently, it may not be straightforward to diagnose a contamination root cause without destructive teardown of the system. Further, upon inspection of a faulty DEF system / DEF electronics module, the contaminant may not be visible to the naked eye, making diagnosis of contaminant ingress challenging. Furthermore, in some cases, where the contaminant subsequently migrates away from the electronics module (e.g. through a process such as evaporation or rebalancing of partial pressure equilibria), the electronics module may revert to its functionality. Accordingly, it can be challenging to correctly diagnose a change in the behaviour of a DEF electronics module due to the presence of a contaminant. The electronics module of the first aspect includes a contaminant indicator provided within the housing. As such, if the contaminant enters the housing where the electronic component is located, the contaminant indicator will record the presence of the contaminant. By recording the presence of the contaminant, the DEF electronics module of the first aspect allows a fault resulting from ingress of a contaminant to be more easily and quickly diagnosed. In particular, the contaminant indicator will have recorded the presence of the contaminant even if the contaminant subsequently evaporates or is removed from the DEF electronics module. By attributing the fault to contaminant ingress in a quick and reliable manner using the contaminant indicator, the DEF electronics module may be repaired / returned to service in a relatively straightforward and economic manner. According to a second aspect of the disclosure, a DEF header for a DEF system is provided. The DEF header is configured to circulate DEF from a DEF tank of the DEF system to an aftertreatment system for a diesel internal combustion engine. The DEF header comprises a sensor module and a control module, wherein the sensor module and / or the control module is a DEF electronics module according to the first aspect of the disclosure. In some embodiments, the aftertreatment system may include a DEF injector and / or a SCR. According to a third aspect of the disclosure, a DEF system is provided. The DEF system comprises a DEF electronics module according to the first aspect or a DEF header according to the second aspect. The DEF system comprises a DEF tank. The DEF system is configured to circulate DEF from the DEF tank to an aftertreatment system of a diesel internal combustion engine. Brief description of the figures Embodiments of the disclosure will now be described with reference to the following nonlimiting figures in which: Fig. 1 is a block diagram of a DEF system according to an embodiment of the disclosure; Fig. 2 is a schematic diagram of a DEF header according to an embodiment of the disclosure; Fig. 3 is cross sectional view of a DEF electronics module according to an embodiment of the disclosure; Fig. 4 is a further cross-sectional view of the DEF electronics module of Fig. 2; Fig. 5 is a schematic cross-sectional diagram of a lower portion of a DEF header according to an embodiment of the disclosure; and Fig. 6 is a schematic cross-sectional diagram of a DEF electronics module according to an embodiment of the disclosure. Detailed description According to an embodiment of the disclosure, a DEF system 1 is provided. Fig. 1 shows a block diagram of a DEF system 1 according to this disclosure. As shown in Fig. 1, the DEF system 1 comprises a DEF tank 5, and a DEF header 10. As shown in Fig. 1 the DEF system circulates DEF from the DEF tank 5 to an aftertreatment system 3 of a diesel internal combustion engine. The DEF header 10 circulates DEF from the DEF tank 5 to the aftertreatment system 3 via a flow path 7. DEF returns from the aftertreatment system 3 to the DEF tank 5 via a return path 9 and the DEF header 10. Fig. 2 shows a computer-generated diagram of a DEF header 10 according to an embodiment of the disclosure. The DEF header 10 comprises a sensor module 20 and a control module 30. The DEF header 10 also comprises a lower portion 40 and an upper portion 50. The DEF tank 5 defines an internal volume. The internal volume of the DEF tank 5 may store DEF for use in the DEF system 1. The DEF tank 5 may define an opening 6 through which the DEF header 10 may extend. Other openings (not shown in Fig. 1) may be provided in the DEF tank 5, for example to allow DEF to be added to the DEF tank 5 and the like. The DEF header 10 may be configured to circulate DEF from the DEF tank 5 of the DEF system 1 to the aftertreatment system 3. The aftertreatment system 3 may comprise a SCR catalyst (not shown). The aftertreatment system 3 may also include a DEF injector (not shown) which is configured to inject the DEF into an exhaust gas stream. The exhaust gas stream and DEF then flows over the SCR catalyst, in order to reduce the quantity of NOX in the exhaust gas. The DEF header 10 may also include sensing functionality for monitoring one or more variables associated with the DEF system 10. For example, the DEF header 10 may be configured to monitor one or more of: a quantity of DEF present in the DEF tank 5 (e.g. a DEF level sensor), a concentration (e.g. a urea concentration) of the DEF in the DEF tank, a temperature of the DEF in the DEF tank 5 and the like. As shown in Figs. 1 and 2, the DEF header may comprise a lower portion 40 which may be configured to extend from an opening 6 of the DEF tank 5 into the DEF tank 5. As such, the lower portion 40 of the DEF header 10 may be a portion of the DEF header 10 which extends into the internal volume of the DEF tank 5. The lower portion 40 may include a plurality of DEF conduits 42 for circulating DEF to the aftertreatment system 3 and back to the DEF tank 5. The lower portion 40 may also include one or more sensor modules 20. The sensor modules 20 may be located at a distal end of the lower portion 40, opposite the upper portion 50. The lower portion 40 may also a communication passage 44. The communication passage 44 may extend from the upper portion 50 of the DEF header 10 to one or more of the sensor modules 20. In some embodiments, the communication passage 44 may be configured to connect one or more sensor modules 20 to a control module 30. For example, in the embodiment of Figs. 1 and 2, the communication passage 44 connects a sensor module 20 of the lower portion 40 to a control module 30 of the upper portion 50. In other embodiments, the one or more sensor modules 20 may be located in the upper portion 50 and / or the lower portion 40. In some embodiments, a plurality of communication passages 44 may be provided to interconnect the modules 20, 30. The communication passage(s) 44 may be configured to interconnect modules 20, 30 in a manner which isolates an interior of the communication passage 44 from the surrounding environment of the communication passage 44. As such, the communication passage 44 may define a volume in which electrical cables and / or electronic components may be located. In some embodiments, the communication passage 44 may also comprise a contaminant indicator 12. The upper portion 50 of the DEF header 10 may configured to seal the opening 6 of the DEF tank 5. As such, the upper portion of the DEF header 10 may be a portion of the DEF header which extends beyond (i.e. outside) the internal volume of the DEF tank 5. As such, the DEF header 10 may extend through the opening 6 of the DEF tank 5. The control module 30 may be located in the upper portion 50 of the DEF header 10. In other embodiments, the control module 30 may be located in the lower portion 40 of the DEF header 10. The control module 30 may be connected to the sensor module(s) 20 by the communication passage 44. In some embodiments, the control module 30 may be located in the upper portion 50 of the DEF header 10 to allow the control module 30 to be easily connected to other control systems of the internal combustion engine such as an Engine Control Unit (not shown) and the like. By providing the control module 30 in the upper portion 50 of the DEF header 10, exposure of the control module 30 to contaminants from e.g. the DEF tank 5 may be reduced. The inventors have realised that some contaminants, in particular ammonia, may migrate. As such, even if a control module 30 is located substantially outside the DEF tank 5 (e.g. in the upper portion 50 of the DEF header 10), the control module 30 may still be exposed to contaminants which migrate from the DEF tank 5 via the DEF header 10. Embodiments of this disclosure provide one or more DEF electronics modules which includes means for indicating when they have been exposed to one or more contaminants. According to this disclosure, the sensor module 20, control module 30, and communication passage 44 may each be examples of a DEF electronics module according to this disclosure. A DEF electronics module comprises: an electronic component of the DEF system, a housing for the electronic component, and a contaminant indicator provided within the housing. According to this disclosure, a DEF electronics module may be any part of the DEF system 1 which is used to house one or more electronic components. Such electronic components may be at a risk of unintentional exposure to one or more contaminants. Exposure to a contaminant, for example ammonia, may cause an electronic component (or the DEF system 1 overall) to malfunction or behave in an unintended manner. When performing maintenance on the DEF system 1 to diagnose the cause of a malfunction or unintended behaviour, it can be challenging to accurately identify contaminant exposure as the cause of the malfunction / unintended behaviour. For example, ammonia exposure may cause temporary changes in an electronic component. Thus, in some circumstances, subsequent migration (e.g. by evaporation or rebalancing of partial pressure equilibria) of the ammonia from the electronic component may cause the electronic component to function normally. Thus, inspection and / or electrical testing of electronics components of a DEF system 1 may not easily identify malfunctions / unintended behaviour resulting from contaminant exposure. According to this disclosure, a DEF electronics module is provided including one or more contaminant indicators which allow for a relatively quick and straightforward diagnosis of contaminant exposure having occurred. By way of example, a schematic diagram of a control module 30 of the DEF header 10, which is a DEF electronics module according to this disclosure is shown in Figs. 3 and 4. According to this disclosure, an electronic component may be any discrete electronic device or physical electronic component forming part of the DEF system. For example, the electronic component may be: a processor, an integrated circuit, a microprocessor, a Field Programmable Gate Array (FGPA), a logic circuit, a transistor, a diode, a resistor, a capacitor, an inductor, a transformer, and the like. The electronic component may also be a sensor 22 of the DEF system 1. For example, the electronic component may be a temperature sensor, a level sensor, or a concentration sensor. The temperature sensor may be configured to sense a temperature of the DEF system 1, for example a temperature of the DEF in the DEF tank 5. The level sensor may be configured to sense a level of the DEF in the DEF tank. As such, the level sensor may output a value indicative of an amount of DEF within the DEF tank. The concentration sensor may be configured to sense a concentration of the DEF in the DEF tank (e.g. a concentration of urea). The sensor 22 may comprise an ultrasonic sensor, an infrared sensor, a near infrared sensor, a reed switch, an ultrasonic sensor, or an optical refractive index sensor.. In some embodiments, the electronic component may be an electronic circuit (or part of an electronic circuit) comprising a plurality of discrete electronic devices. For example, in some embodiments, the electronic component may be a printed circuit board (PCB) 32 comprising a plurality of discrete electronic components. In some embodiments, the electronic component may include a processor which may be configured to control at least a part of the DEF system 1. In some embodiments, the processor may be configured to receive signals from one or more sensors 22 of the DEF system 1. For example, in the DEF header 10 of Fig. 2, a processor may be provided within the control module 30. In some embodiments, one or more sensors 22 may be provided within the sensor module 20. In the control module 30 of Figs. 3 and 4, a PCB 32 is provided one which one or more processors (not shown) may be provided. According to this disclosure, in a DEF electronics module, the one or more electronic components are provided within a housing. The cross-sectional views of Figs. 3 and 4 show the control module housing 34 which surrounds the PCB 32. The housing may provide an enclosure for the one or more electronic components. That is to say, the housing may define a chamber 35 in which the one or more electronic components are located. The housing may be configured to isolate the one or more electronic components from the surrounding environment. For example, the housing may isolate the electronic components from the DEF provided within the DEF tank 5. In some embodiments, the housing may be formed from any suitable material, or a composite of materials. In some embodiments, the housing may comprise a metal such as aluminium. In other embodiments, the housing may comprise plastic. The control module housing 34 of Figs. 3 and 4 may comprise a plastic or composite material. It will be appreciated that the housing for a DEF electronics module may take various shapes and form depending on the electronic components to be accommodated within the housing and the space available for the housing. For the control module 30 of Figs. 3 and 4, the control module housing 34 is one part of a two-part assembly. A second part (not shown) having a similar construction may be connected to the control module housing 34 to define a cavity 35 in which the PCB 32 is located. The housing may also include one or more openings 39 which connect the interior of the control module 30 to the interior of a communication passage 44. In some embodiments, a potting compound may be provided within the housing. The potting compound may be configured to encase the electronic component and / or the contaminant indicator (discussed in more detail below). The potting compound may be provided to fill a volume within a cavity 35 of a DEF electronics module which is not occupied by an electronics component and the like. The potting compound may provide additional environmental protection for any electronic component it encases. The potting compound may also be configured to provide a hermitic seal for the DEF electronics module. Various materials may be used as a potting compound, as known by the skilled person. For example, in some embodiments, a potting compound may comprise a resin, or a plastic, an elastomer, an epoxy or a composite material comprising any of: a resin, or a plastic, an elastomer, an epoxy. In some embodiments, a potting compound may be a composite material comprising a potting matrix and a potting particulate, such as glass beads or plastic balls. In addition to the one or more electronic components, a contaminant indicator 36 is also provided within the housing of a DEF electronics module. The contaminant indicator 36 may be configured to record the presence of a contaminant within the housing. According to this disclosure, a contaminant may be considered to be any chemical, element or molecule which the housing is configured to exclude from the electronic component. Upon exposing the electronic component to a contaminant, the contaminant may cause a temporary or permanent change in the behaviour of the electronic component. Examples of contaminants according to this disclosure include urea, ammonia, water, isocyanic acid, derivatives of urea, derivatives of ammonia, derivatives of isocyanic acid, water, and organic compounds such fuel, or coolant, and the like. A contaminant indicator 36 may be configured to record the presence of a specific contaminant. In some embodiments, a contaminant indicator 36 may be configured to record the presence of a select group of contaminants. The skilled person may select the contaminant indicator 36 based on the contaminants to be detected in the DEF electronics module. For example a contaminant indicator 36 may be configured to record the presence of one or more of: urea, isocyanic acid, ammonia, water or derivatives thereof. In some embodiments, a plurality of contaminant indicators 36 may be provided within the housing. In some embodiments the plurality of contaminant indicators 36 may be distributed throughout the housing. For example, in the control module shown in Fig. 4 (where the PCB is shown in transparent form), a plurality of contaminant indicators 36 are provided. Each contaminant indicator may be provided as an elongate strip which may be attached to an interior surface of the control module housing 34. In embodiments where a potting compound is provided (see below), the plurality of contaminant indicators may be distributed throughout the potting compound. According to this disclosure, different types of contaminant indicator 36 may be provided, depending on the desired functionality of the contaminant indicator 36. In some embodiments, the contaminant sensor 36 may comprise a chemical sensor configured to react to the presence of a contaminant in the housing. In some embodiments, the chemical sensor may be configured to permanently a physical property of the chemical sensor (e.g. change colour) in response to the presence of a contaminant in the housing. For example, in some embodiments, the chemical sensor may comprise a sensor strip which is impregnated with a chemical which is configured to react in the presence of one or more contaminants. The sensor strip may comprise paper, fabric, or any other suitable material. When the chemical of the sensor strip reacts with a contaminant, the resulting reaction product(s) may cause the sensor strip to change colour or be visually identifiable in any other suitable manner. As such, a chemical sensor may be provided to provide an immediate visible indication that a chamber 35 of a DEF electronics module has been exposed to a contaminant upon inspection. For example, in the control module 30 of Figs. 3 and 4, one or more of the contaminants sensors 36 may be a chemical sensor comprising a sensor strip as described above. In some embodiments, a chemical sensor may be distributed throughout a potting material 26. As such, a plurality of discrete chemical sensors may be distributed though the potting material 26. Upon exposure to a contaminant, the potting material may visibly indicate contaminant exposure (e.g. through a colour change) as a result of a reaction of the chemical sensor. In addition to, or as an alternative to the chemical sensors described above, in some embodiments, one or contaminant indicators 36 may comprise an electronic sensor configured to detect to the presence of a contaminant in the housing. Various different electronic sensors for contaminants are known to the skilled person. For example, the electronic sensor may be an electrochemical gas sensor which may be configured to detect the presence of a contaminant gas, such as hydrogen, ammonia and the like. In some embodiments, the electronic sensor may comprise a conductive grid, wherein the conductive grid may be configured to change conductivity when exposed to ammonia in order to detect the presence of ammonia. In some embodiments, the conductive grid may comprise a grid of wires. The grid of wires may comprise a metallic material, for example aluminium or copper wires. The wires may be provided as a conductive grid in order to increase the surface area of the electronic sensor. Upon exposure to a contaminant (e.g. ammonia gas), the conductivity of the grid may change, allowing the presence of a contaminant to be detected (as a change in the conductivity of the grid). In some embodiments, the electronic sensor may be connected to a processor of the DEF system 1. For example in the embodiment of Figs. 3 and 4, one or more of the contaminant indicators 36 may be electronic sensor. Each electronic sensor may be configured to communicate with a processor provided on the PCB 32. Upon receiving a signal from the electronic sensor which is indicative of the presence of a contaminant within the housing, the processor may be configured to output an alert indicating that contaminant is present in the housing. In some embodiments, the one or more electronic sensors may be used to monitor a DEF electronics module in real time. Upon detecting the presence of a contaminant, the processor may then prompt the DEF system 1 to change is operating status to try to reduce the influx of the contaminant. For example, upon receiving a signal from the electronic sensor which is indicative of the presence of a contaminant within the housing, the processor may be configured to output a signal to cause a temperature of the DEF system to be reduced. As contaminant migration may be driven by diffusion, reducing a temperature of the DEF system may reduce the rate at which DEF electronics module is exposed to a contaminant. Such a reduction may reduce the risk of contaminant levels reaching a level within the DEF electronics module which causes a change in the behaviour of the electronic component. In some embodiments, upon receiving the signal from the electronic sensor which is indicative of the presence of a contaminant within the housing, the processor is configured to receive the signal for a predetermined buffer time before outputting the signal to cause the temperature of the DEF system to be reduced. As such, the controller may implement a buffer time to reduce the risk of a false positive detection event prompting the processor to change the operating status of the DEF system 1. For example, upon receiving the signal for a predetermined buffer time, the processor may escalate an error code to indicate to a service engineer that further action is required (e.g. component or seal replacement, or pre-emptive action required). In some embodiments, to further reduce the risk of contaminant exposure affecting the electronic exposure, the DEF electronics module may comprise a contaminant adsorption material which is configured to adsorb the contaminant when the contaminant is present in the housing. For example, in the embodiment of Figs. 3 and 4, the control module 30 is provided with three strips of contaminant adsorption material 38. In the embodiment of Figs. 3 and 4, the contaminant adsorption material 38 may be configured to adsorb ammonia. For example, a suitable contaminant adsorption material 38 may comprise activated charcoal. In other embodiments, a contaminant adsorption material 38 may be configured to adsorb water such as silica gel. In some embodiments, a combination of different contaminant adsorption materials 38 may be provided, wherein each contaminant adsorption material 38 may be configured to adsorb a different contaminant. In some other embodiments, a DEF electronics module for a DEF system 1 of a diesel internal combustion engine may comprise an electronic component of the DEF system 1, a housing for the electronic component, wherein the electronic component is provided within the housing and a contaminant adsorption material 38 which is configured to adsorb the contaminant when the contaminant is present in the housing. While in the embodiment of Figs. 3 and 4, the contaminant adsorption material 38 is provided as strips attached to the control module housing 34, in other embodiments, the contaminant adsorption material 38 may be provided in other forms. For example, in some embodiments, the contaminant adsorption material 38 may be distributed throughout a potting material 26 provided within the housing. Thus, according to this disclosure, a DEF electronics module may be provided which incorporates one or more contaminant indicators 36 to aid with the diagnosis of a fault or unintended behaviour of a DEF system 1 resulting from contaminant exposure. As discussed above, a DEF electronics module according to this disclosure may be a sensor module 20 of a DEF header 10. Fig. 5 shows a schematic cross-section of the lower portion 40 of the DEF header 10 including a first sensor module 20a, a second sensor module 20b, and a communication passage 44. As shown in Fig. 5, the lower portion 40 has a generally L-shaped cross section. The first sensor module 20a is provided at one end of the L-shaped cross section. As shown in Fig. 5, the first sensor module 20a comprises a first sensor 22a of the DEF system, first sensor housing 24a for the first sensor 22a, and a contaminant indicator 36. The first sensor 22a may be a DEF level sensor for example. The contaminant indicator may be provided in accordance with the contaminant indicators 36 discussed above. The second sensor module 20b comprises a second sensor 22b, a second sensor housing 24b, a contaminant indicator 36, a potting material 26, a communication passage 44, and a contaminant adsorption material 38. As shown in Fig. 5, the communication passage 44 is connected to the interior of the second sensor housing 24b such that the communication passage 44 is effectively an extension of the cavity 25 in which the second sensor 22b is located. That is to say, the communication passage 44 effectively forms part of the housing of a DEF electronics control module according to this disclosure. As shown in Fig. 5, the second sensor 22b is surrounded by the potting material 26. The potting material partially fills the cavity 25 defined by the second sensor housing 24b. The contaminant indicator 36 is provided in a portion of the cavity 25 which is not filled by the potting material 26. As shown in Fig. 5, the communication passage comprises one or more cables 46 which connect the first and second sensor modules 20a, 20b to the control module 30. The communication passage also includes a contaminant indicator 36 and a contaminant adsorption material 38. Thus, inspection of the communication passage 44 may indicate if the interconnected modules 20a, 20b, 30 may have been exposed to a contaminant. While the contaminant adsorption material 38 and the sensors 22a, 22b are shown as generally rectangular cross sections, it will be appreciated that the contaminant adsorption material 38 and the sensors 22a may be provided in any suitable shape and / or arrangement relative to the respective housings 24a, 24b. For example, the contaminant adsorption material 38 and the sensors 22a, 22b may each be provided as strips in the communication passage 44 which encircle the cable 46 about its circumference. In other embodiments, the contaminant adsorption material 38 and / or the sensors 22a, 22b may each be attached to an interior surface of the sensor housing 24a, 24b or the communication passage 44. As such, it will be appreciated that the shape and / or position of the contaminant adsorption material 38 and the sensors 22a, 22b may be provided in any suitable position of the respective sensor module 20a, 20b depending on the space available. Fig. 6 shows a further cross-sectional schematic diagram of a sensor module 30 of a DEF system 1, which may be a DEF electronics module according to this disclosure. The sensor module 30 may be provided as part of a DEF header 10. The sensor module 30 of Fig. 6 is configured to be submerged in DEF when in normal use. As such, the sensor module 30 may be subject to a relatively high rate of contaminant migration. As shown in Fig. 6, the DEF electronics module comprises a sensor housing 24a, which defines a first cavity 35a, a second cavity and a third cavity 35c. The first, second and third cavities 35a, 35b, 35c are interconnected. As shown in Fig. 6, the first cavity 35a of the DEF electronics module comprises a first sensor 22a. The third cavity comprises a second sensor 22b. The second cavity comprises a PCB 32. Each of the sensors 22a, 22b is encased in a potting material 26. Each cavity 35a, 35b, 35c of the DEF electronics module comprises at least one contaminant indicator 36. As shown in Fig. 6, the second cavity 35b comprises a plurality of contaminant indicators 36. In the embodiment of Fig. 6 each of the contaminant indicators 36 may be configured to detect ammonia. In some embodiments, one or more contaminant indicators 36 configured to detect water may also be provided in one or more of the cavities 35a, 35b, 35c. Each of the cavities may also be provided with a contaminant adsorption material 38. Thus, according to this disclosure a DEF electronics module for a DEF system 1 is provided. Industrial applicability According to this disclosure, a DEF electronics module is provided. The DEF electronics module may form part of a DEF system for a diesel internal combustion engine, for example a DEF header. The DEF electronics module of the first aspect provides a housing for the electronic component which provides some insulation from contaminants for the electronic component. A contaminant indicator is provided within the housing which is configured to record the presence of a contaminant in the housing. As such, if the contaminant enters the housing where the electronic component is located, the contaminant indicator may permanently record the presence of the contaminant. By recording the presence of the contaminant, the DEF electronics module allows a fault resulting from ingress of a contaminant to be more easily and quickly diagnosed. In particular, the contaminant indicator will have recorded the presence of the contaminant even if the contaminant subsequently migrates (e.g. by evaporation)or is removed from the DEF electronics module. By attributing the fault to contaminant ingress in a quick and reliable manner using the contaminant indicator, the DEF electronics module may be repaired / returned to service or replaced in a relatively straightforward and economic manner. In some embodiments, the DEF electronics module may also include a contaminant adsorption material within the housing. The contaminant adsorption material may help to reduce or prevent contaminant ingress from affecting the behaviour of an electronic component within the DEF electronics module. The contaminant adsorption material may also extend the durability of the lifetime of the DEF electronics module and / or the DEF header 10 / DEF system 1. While the contaminant adsorption material 38 may adsorb small quantities of contaminant ingress, it will be appreciated that that the provision of a contaminant indicator 36 may be helpful in quickly identifying events where contaminant ingress has surpassed the capacity of the contaminant adsorption material 38.

Claims

1. A diesel exhaust fluid (DEF) electronics module for a DEF system of a diesel internal combustion engine, the DEF electronics module comprising:an electronic component of the DEF system;a housing for the electronic component, wherein the electronic component is provided within the housing; anda contaminant indicator provided within the housing, the contaminant indicator being configured to record the presence of a contaminant within the housing.

2. A DEF electronics module according to claim 1, wherein the electronic component comprises one or more of:a processor configured to control at least part of the DEF system, and / or to receive signals from one or more sensors of the DEF system;a sensor configured to sense a property of the DEF system; and a printed circuit board.

3. A DEF electronics module according to any preceding claim, wherein the contaminant indicator is configured to record the presence of one or more of: ammonia, water, or hydrogen.

4. A DEF electronics module according to any preceding claim, wherein the contaminant indicator comprises a chemical sensor configured to react to the presence of a contaminant in the housing.

5. A DEF electronics module according to claim 4, wherein the chemical sensor is configured to permanently change colour in response to the presence of a contaminant in the housing.

6. A DEF electronics module according to any preceding claim, wherein the housing further comprises a contaminant adsorption material which is configured to adsorb the contaminant when the contaminant is present in the housing.

7. A DEF electronics module according to any preceding claim, whereinthe contaminant indicator comprises an electronic sensor configured to detect to the presence of a contaminant in the housing.

8. A DEF electronics module according to claim 7, whereinthe electronic sensor comprises a conductive grid, the aluminium grid configured to change conductivity when exposed to ammonia in order to detect the presence of ammonia.

9. A DEF electronics module according to claim 7 or claim 8, whereinthe electronic sensor is connected to a processor of the DEF system, wherein upon receiving a signal from the electronic sensor which is indicative of the presence of a contaminant within the housing, the processor is configured to output an alert indicating that contaminant is present in the housing.

10. A DEF electronics module according to claim 9, whereinupon receiving a signal from the electronic sensor which is indicative of the presence of a contaminant within the housing, the processor is configured to output a signal to cause a temperature of the DEF system to be reduced.

11. A DEF electronics module according to claim 10, whereinupon receiving the signal from the electronic sensor which is indicative of the presence of a contaminant within the housing, the processor is configured to receive the signal for a predetermined buffer time before outputting the signal to cause the temperature of the DEF system to be reduced.

12. A DEF electronics module according to any preceding claim, further comprising a potting compound, the potting compound being provided within the housing, wherein the potting compound is configured to encase the electronic component and / or the contaminant indicator.

13. A DEF electronics module according to any preceding claim, whereina plurality of contaminant indicators are provided within the housing, the plurality of contaminant indicators being distributed throughout the potting compound.

14. A DEF header for a DEF system, the DEF header configured to circulate DEF from a DEF tank of the DEF system to a selective catalytic reduction system of a diesel internal combustion engine, the DEF header comprising:a sensor module; anda control module, wherein the sensor module and / or the control module is a DEF electronics module according to any of claims 1 to 13.

15. A DEF header according to claim 14, whereinthe sensor module is a DEF electronics module comprising:a sensor of the DEF system;a sensor housing for the sensor, wherein the sensor is provided within the sensor housing; anda contaminant indicator provided within the sensor housing, the contaminant indicator configured to record the presence of a contaminant within the sensor housing; andthe control module is a DEF electronics module comprising:a processor of the DEF system;a control housing for the processor, wherein the processor is provided within the control housing; anda contaminant indicator provided within the control housing, the contaminant indicator configured to record the presence of a contaminant within the control housing.

16. A DEF header according to claim 14 or 15, further comprising:an upper portion; anda lower portion,wherein the lower portion of the DEF header is configured to extend from an opening of the DEF tank into the DEF tank, andthe upper portion of the DEF header is configured to seal the opening of the DEF tank.

17. A DEF header according to claim 16, whereinthe sensor module is located in the lower portion of the DEF header; andthe control module is located in the upper portion of the DEF header.

18. A DEF header according to claim 16 or claim 17, wherein the lower portion comprisesa communication passage which is configured to extend from the sensor module to the upper portion of the DEF header, wherein the sensor module is electrically connected5 to the control module through the communication passage.

19. A DEF header according to claim 18, whereinthe communication passage further comprises a contaminant indicator and / or comprises a contaminant adsorption material which is configured to adsorb the10 contaminant.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS:CLAIMS:

1. A diesel exhaust fluid (DEF) electronics module for a DEF system of a diesel internal combustion engine, the DEF electronics module comprising:5 an electronic component of the DEF system;a housing for the electronic component, wherein the electronic component is provided within the housing; anda contaminant indicator provided within the housing, the contaminant indicator being configured to record the presence of a contaminant within the housing;10 wherein the contaminant indicator comprises a chemical sensor configured to reactto the presence of a contaminant in the housing.

2. A DEF electronics module according to claim 1, wherein the electronic component comprises one or more of:''J 15 a processor configured to control at least part of the DEF system, and / or to receiveC\Jsignals from one or more sensors of the DEF system;CM a sensor configured to sense a property of the DEF system; anda printed circuit board.CO20 3. A DEF electronics module according to any preceding claim, whereinthe contaminant indicator is configured to record the presence of one or more of: ammonia, water, or hydrogen.

4. A DEF electronics module according to claim 1, wherein25 the chemical sensor is configured to permanently change colour in response to thepresence of a contaminant in the housing.

5. A DEF electronics module according to any preceding claim, wherein the housing further comprises a contaminant adsorption material which is30 configured to adsorb the contaminant when the contaminant is present in the housing.

6. A DEF electronics module according to any preceding claim, whereinthe contaminant indicator comprises an electronic sensor configured to detect to the presence of a contaminant in the housing.

357. A DEF electronics module according to claim 6, whereinthe electronic sensor comprises a conductive grid, the aluminium grid configured to change conductivity when exposed to ammonia in order to detect the presence of ammonia.

58. A DEF electronics module according to claim 6 or claim 7, whereinthe electronic sensor is connected to a processor of the DEF system, wherein upon receiving a signal from the electronic sensor which is indicative of the presence of a contaminant within the housing, the processor is configured to output an alert indicating10 that contaminant is present in the housing.

209. A DEF electronics module according to claim 8, whereinupon receiving a signal from the electronic sensor which is indicative of the presence of a contaminant within the housing, the processor is configured to output a signal to cause a temperature of the DEF system to be reduced.

10. A DEF electronics module according to claim 9, whereinupon receiving the signal from the electronic sensor which is indicative of the presence of a contaminant within the housing, the processor is configured to receive the signal for a predetermined buffer time before outputting the signal to cause the temperature of the DEF system to be reduced.

11. A DEF electronics module according to any preceding claim, further comprising a potting compound, the potting compound being provided within the housing,25 wherein the potting compound is configured to encase the electronic component and / or the contaminant indicator.

12. A DEF electronics module according to any preceding claim, whereina plurality of contaminant indicators are provided within the housing, the plurality of 30 contaminant indicators being distributed throughout the potting compound.

13. A DEF header for a DEF system, the DEF header configured to circulate DEF from a DEF tank of the DEF system to a selective catalytic reduction system of a diesel internal combustion engine, the DEF header comprising:35 a sensor module; anda control module, wherein the sensor module and / or the control module is a DEF electronics module according to any of claims 1 to 12.

14. A DEF header according to claim 13, wherein5 the sensor module is a DEF electronics module comprising:a sensor of the DEF system;a sensor housing for the sensor, wherein the sensor is provided within the sensor housing; anda contaminant indicator provided within the sensor housing, the contaminant10 indicator configured to record the presence of a contaminant within the sensor housing;and15the control module is a DEF electronics module comprising:a processor of the DEF system;a control housing for the processor, wherein the processor is provided within the control housing; anda contaminant indicator provided within the control housing, the contaminant indicator configured to record the presence of a contaminant within the control housing.CO 1520A DEF header according to claim 13 or 14, further comprising: an upper portion; and a lower portion,wherein the lower portion of the DEF header is configured to extend from anopening of the DEF tank into the DEF tank, andthe upper portion of the DEF header is configured to seal the opening of the DEF 25 tank.

16. A DEF header according to claim 15, whereinthe sensor module is located in the lower portion of the DEF header; and the control module is located in the upper portion of the DEF header.3017. A DEF header according to claim 15 or claim 16, wherein the lower portion comprisesa communication passage which is configured to extend from the sensor module to the upper portion of the DEF header, wherein the sensor module is electrically connected35 to the control module through the communication passage.CM18. A DEF header according to claim 17, whereinthe communication passage further comprises a contaminant indicator and / or comprises a contaminant adsorption material which is configured to adsorb the5 contaminant.

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