GB2529163A

GB2529163A - Fluid detection and storage system for use in a vehicle

Info

Publication number: GB2529163A
Application number: GB1414203.8A
Authority: GB
Inventors: Kunal Dhande
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2014-08-11
Filing date: 2014-08-11
Publication date: 2016-02-17
Anticipated expiration: 2034-08-11
Also published as: GB201414203D0; GB2529163B

Abstract

Fluid storage apparatus 20 for storing a fluid (e.g. urea or ammonia for selective catalytic reduction (SCR)) for dosing into the exhaust gas of an internal combustion engine. The apparatus comprises a main reservoir 26, for storage of the fluid prior to dosing, a second reservoir 24, for temporary storage of the fluid prior to the main reservoir, and sensor(s) 32, 34 for detecting at least one parameter (e.g. density, viscosity, colour and/or refractive index) of the fluid within the second reservoir. A fluid type is determined based on the parameter(s), and a valve 44 opens and closes fluid communication between the reservoirs in response to the determined fluid type so as to prevent communication if fluid does not correspond to an expected fluid type. At least one LED 50 may be provided to indicate whether the valve is open or closed, and/or to indicate that the main and/or second reservoir is full. A method for filling the main reservoir is also disclosed.

Description

FLUID DETECTION AND STORAGE SYSTEM FOR USE IN A VEHICLE

TECHNICAL FIELD

The present invention relates generally to a fluid storage system for storing an aqueous urea solution for dosing into the exhaust gas stream of an internal combustion engine. More specifically, the present invention relates to apparatus and a method for storage of an ammonia-containing reagent for dosing into the exhaust gas stream of an internal combustion engine.

BACKGROUND

It is well known that internal combustion engines can produce undesirable chemical species in their exhaust streams. Under the high temperatures of a combustion IS event, a number of undesirable products are produced from the oxidation of hydrocarbon fuels, including the oxides of nitrogen (NO and NO2, collectively referred to as NO,). Due to their impact on human health, many countries in the global community have enacted legislation that seeks to limit the emission of NO, from both mobile and stationary sources, and many techniques have been developed to achieve this objective.

The use of catalysis technology in particular has been found to be effective in reducing NO, emissions from internal combustion engines. One well-known technique for remediating NO, is Selective Catalytic Reduction (hereafter referred to as 5CR). In this approach, an aqueous urea solution in the form of an ammonia-containing reagent (or reductant) is injected into an exhaust stream at a rate closely related to the instantaneous NO, content of the stream. In conjunction with a vanadia-based or similar catalyst, the ammonia (NH3) reacts with the NO,, converting the pollutant to harmless nitrogen (N2) and water (H20) in the tail gas.

One widely used ammonia-containing product for use within the 5CR system is AdBIue®, an aqueous urea solution composed of 32.5% urea and 67.5% deionised water. Referring to Figure 1, vehicles using SCR are equipped with an aqueous urea storage tank 10, in addition to the standard fuel tank. The aqueous urea tank 10 is accessed through a filler neck 12, which is often located towards the rear of the vehicle, in the boot. The aqueous solution 14 is transferred from the storage tank 10 and injected under pressure into the exhaust gas stream, where the deionised water evaporates and the urea decomposes, producing reagents which react with the NO, compounds in the presence of the catalyst.

The storage tank 10 may also house a level sensor 16, indicating the level of aqueous urea solution 14 contained within the tank 10. Within some vehicles a gauge is used to communicate the detected level to the vehicle user and/or a warning is displayed on the dashboard to inform the user when the level falls below a critical point. The user is then required to remove a filler cap (not shown) positioned over the filler neck 12, and to feed in more of the aqueous urea solution 14.

While a well-established and widely-used technology, there are a number of shortcomings associated with the present process of storing and dosing the ammonia-containing reagent 14 within the vehicle. The concentration of urea in the aqueous urea solution 14 is critical, with limits of 32.5 +/-2%, above and below which Is adverse effects may be experienced. Any contaminants present in the aqueous urea solution 14 will collect within the SCR system, which, over a period of time, can cause blockages. Other potential consequences include: thermal effects in the event that the storage tank is filled with diesel or petrol, including the possibility of explosions; less effective remediation of undesirable chemical species; and, damage to and possible failure of the SCFI system.

In the event that the storage tank 10 is filled with an incorrect fluid (not shown) the tank 10 requires emptying. The user is generally unable to drain the storage tank 10 themselves and so will be required to take the vehicle to a garage, at significant time and financial expense. The user will either need to pay to have the vehicle towed to a garage, or will be required to drive the vehicle to the garage themselves. In the event that the user drives the vehicle to the garage the incorrect fluid may progress through the SCR system, potentially causing one or more of the adverse effects mentioned.

Despite the tight tolerance on urea concentration, with the system at present it is relatively easy to feed in an incorrect fluid. This can occur by: filling the storage tank with an aqueous urea solution of inccrrect urea concentration; or, by filling the storage tank 10 with a different fluid altogether, whether intentionally or unintentionally.

Current SCR systems are equipped with NO, sensors upstream and downstream of the NO, conversion, where the NO, levels recorded may indicate that an incorrect fluid has been inputted into the storage tank. However, the sensors only operate on starting of the engine and are therefore unable to detect potential issues with the fluid before the vehicle is started.

It is an object of the present invention to provide a reagent storage system which substantially overcomes or mitigates the aforementioned problems. It is a further object of the invention to provide an advantageous method of operating such a storage system.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided fluid storage apparatus for storing a fluid for dosing into the exhaust gas stream of an internal combustion engine, the apparatus comprising a main reservoir for storage of the fluid Is prior to dosing into the exhaust gas stream; a second reservoir, separate from the main reservoir, for temporary storage of the fluid prior to delivery to the main reservoir; and a sensor arrangement for detecting at least one parameter of the fluid within the second reservoir. The apparatus may further comprise means for determining a fluid type based on the at least one parameter; and a valve means for controlling communication between the main reservoir and the second reservoir. The valve means corresponds to a ready-to-fill state for the apparatus in which fluid communication between the main reservoir and the second reservoir is closed and a not-ready-to-fill state for the apparatus in which fluid communication between the main reservoir and the second reservoir is open. The valve means is operable in response to the determination of the fluid type so as to prevent communication between the second reservoir and the main reservoir in the event that the fluid does not correspond to an expected fluid type.

A fluid storage apparatus has been developed that can be used to ensure an expected fluid has been fed into the secondary reservoir, before this is able to pass into the main reservoir for dosing into the SCR system of a vehicle. This prevents the collection of contaminants within the SCR system as a result of feeding a fluid of incorrect concentration or an incorrect fluid into the main reservoir, reducing the likelihood of blockages, thermal effects, ineffective remediation of undesirable chemical species and damage to the 5CR system.

In one example, the second reservoir is detached from the main reservoir in a separate housing.

In another example, the second reservoir is integrated with or located within the main reservoir, providing a particularly convenient packaging arrangement.

The sensor arrangement includes a density and viscosity (DN) sensor so as to provide an indication of the fluid type in one possible embodiment.

The sensor arrangement may also include a sensor for determining the colour of the fluid so as to provide an indication of the fluid type.

A sensor configured to determine the refractive index of the fluid may also be included, so as to provide an indication of the fluid type. Is

In a particular embodiment of the invention, the expected fluid type is an aqueous urea solution.

In one example, the aqueous urea solution has a urea concentration within the range of 32.5 +1-2%.

The main reservoir may be provided with a main level sensor for monitoring the level of fluid stored therein. This may be used to inform a control unit, in the form of an Electronic Control Unit (ECU), of the level of fluid within the main reservoir, in order to trigger a particular sequence of events when the level of fluid passes a certain value.

The second reservoir may also be provided with a second level sensor for monitoring the level of fluid stored therein. This lev& sensor may be used to detect when the so level of fluid has passed a certain point on filling, to avoid overflow of the fluid.

There may also be provided a means for alerting a user that the apparatus is in the ready-to-fill state in which the valve means is closed. This may provide the user with greater confidence in the system, only informing the user that they should pour fluid into the system when the apparatus is ready.

The means for alerting includes at least one light emitting diode (LED) in one possible embodiment.

A first LED of a first colour may be provided to indicate the ready-to-fill state.

In an embodiment, a second LED of a second colour may also be provided to indicate that the main reservoir and/or the second reservoir are full.

The second LED may also be configured to indicate the not-ready-to-fill state. The use of LEDs increases the ease with which the system is used and interpreted.

Alerting the user to the not-ready-to-fill state as well as the ready-to-fill state leaves no room for ambiguity as to the necessary course of action.

In one example, the sensor arrangement is operable to determine the at east one parameter of the fluid only when the apparatus is in the ready-to-fill state. This ensures that the sensors are only in operation when the valve means has sealed connection between the secondary reservoir and the main reservoir.

A drain means is provided in one embodiment, for evacuation of the second reservoir in the event that the fluid in the second reservoir does not correspond to the expected fluid type. Compared to the prior art, this offers an inexpensive and straightforward means for evacuating the second reservoir of its contents, should this be necessary.

The apparatus may further comprise means for alerting the vehicle user that the level of fluid in the main reservoir is less than a predetermined threshold level so as to prompt the user to fill the main reservoir with fluid. Prompting the user to replenish the main reservoir with fluid may prevent the level dropping until the reservoir is substantially empty. In one example, this reduces the likelihood of the engine running without sufficient aqueous urea solution in the main reservoir, where this could lead to increased levels of undesirable chemical species in the exhaust gas.

In one embodiment, there may be provided a vehicle comprising the fluid storage apparatus as described previously.

According to another aspect of the present invention, a method is provided for filling a main reservoir with fluid for dosing into the exhaust gas stream of an internal combustion engine, the method comprising temporarily storing the fluid in a second reservoir prior to delivery to the main reservoir; detecting at least one parameter of the fluid within the second reservoir; and determining a fluid type based on the at least one parameter. The method may further comprise controlling fluid communication between the main reservor and the second reservoir in response to the determination of the fluid type, a ready-to-fill state corresponding to fluid communication between the main reservoir and the second reservoir being closed and a not-ready-to-fill state corresponding to fluid communication between the main reservoir and the second reservoir being open, so as to prevent communication between the second reservoir and the main reservoir in the event that the fluid does not correspond to an expected fluid type.

Is The method may comprise monitoring the level of fluid in the main reservoir and alerting the user when the level falls below a predetermined threshold level.

In one embodiment, the method comprises controlling a valve means to open and close fluid communication between the main reservoir and the second reservoir.

Alerting the user of the ready-to-till state, in which the fluid communication between the main reservoir and the second reservoir is closed, is also included in a particular embodiment.

The method may include detecting at least one parameter of the fluid only when the apparatus is in the ready-to-fill state.

In one example, the density and viscosity of the fluid is detected to determine the fluid type.

In another example, the colour of the fluid is detected to determine the fluid type.

The refractive index of the fluid may also be detected to determine the fluid type.

In the event that the fluid in the second reservoir does not correspond to the expected fluid type the user may be alerted.

Further, the method may comprise draining the second reservoir in the event that the fluid in the second reservoir does not correspond to the expected fluid type.

In one embodiment, in the event that the fluid in the second reservoir does correspond to the expected fluid type, the method comprises opening fluid communication between the main reservoir and the second reservoir.

In one particular example, the expected fluid is an aqueous urea solution.

The aqueous urea solution has a urea concentration within the range of 32.5 +/-5% in

another example.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination.

Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which like components are assigned like numerals, and in which:-Figure 1 shows a known fluid storage system for storing of a reagent for dosing into the exhaust gas stream of an internal combustion engine.

Figure 2 shows a fluid storage system of one embodiment of the invention n normal operation, with the level of an aqueous urea solution in the main tank above a predetermined threshold level; Figure 3 shows the fluid storage system of Figure 2, where the level of aqueous urea solution in the main tank has fallen below the predetermined threshold level; Figure 4 shows the fluid storage system of Figure 3, and depicting the signals transmitted in the event that the level of aqueous urea in the main tank has fallen below the predetermined threshold level; Figure 5 shows the fluid storage system of Figure 2, where a fluid is being fed into the filler neck of the system; Figure 6 shows the fluid storage system of Figure 5, where the tilling fluid is an aqueous urea solution of correct concentration; Figure 7 shows the fluid storage system of Figure 6, where the aqueous urea solution of correct concentration has been ted into the system and is able to pass into the main tank; Is Figure 8 shows the fluid storage system of Figure 5, and depicting the signals transmitted in the event that the filling fluid is an aqueous urea solution of incorrect urea concentration or the filling fluid is not an aqueous urea solution; Figure 9 shows the fluid storage system of Figure 8, where the incorrect fluid is drained from the system; and Figure 10 shows the fluid storage system of Figure 2, depicting the signals transmitted in the event that the level of aqueous urea solution within the main tank is above the predetermined threshold level and a fluid is fed into the filler neck.

DETAILED DESCRIPTION

Referring to Figure 2, a fluid storage system 20 with the ability to detect at least one parameter of a fluid 21 (shown in Figure 5) to be delivered to the SCR system of a vehicle is shown. In correct operation of the system, it is intended that the fluid 21 is an aqueous urea solution 22 with urea concentration between the limits of 32.5 +1- 2%. The aqueous urea solution 22 is stored within the system 20 prior to dosing into the exhaust duct of the vehicle, where it provides reagents to reduce undesirable NO compounds to water and nitrogen for expulsion in the tail gas.

The system 20 comprises two tanks, or reservoirs: a small tank, or second reservoir 24, used as a temporary storage location for the fluid 21 during detection of at least one parameter of the fluid 21 for determination of the fluid type; and, a larger main tank, or main reservoir 26, as featured in present SCR systems, used for storage of the aqueous urea solution 22 prior to delivery of the solution 22 into the exhaust duct.

In this example, the small tank 24 is detached from the main tank 26 in a separate housing. Both the small tank 24 and the main tank 26 contain a level sensor: a second level sensor 28 in the small tank 24 and a main level sensor 30 in the main tank 26. In addition to this, the small lank 24 houses a colour sensor 32 and a density and viscosity sensor 34 (hereafter referred to as a DIV sensor). Density, viscosity and colour sensing technology such as this is well known. A drain means in the form of a drain valve 36 is connected to the small tank 24, such that it can be used to evacuate the tank 24 of its contents.

A first conduit 38 connects a filler neck 40: positioned towards the rear of the vehicle and accessible by the vehicle user, to the small tank 24, with a second conduit 42 IS connecting the small tank 24 to the main tank 26. Typically, the filler neck 40 is located in the vehicle boot. A valve means in the form of a valve 44 is provided within the second conduit 42 in order to control the flow of aqueous urea solution 22 between the two tanks. In one embodiment of the invention the valve 44 is a butterfly valve.

Signals are transmitted to and from a control unit in the form of an Electronic Control Unit 46 (hereafter referred to as an ECU), which monitors and controls the electronic components within the system 20. The signals include a signal (not shown) from the ECU 46 to Light Emitting Diodes (LEDs) 50 positioned in close proximity to the filler neck 40.

For the purpose of the following description, various signal paths are shown in the figures. Referring again to Figure 2, a cap (not shown) on the filler neck 40 is provided with a sensor (not shown), used to determine the open' or closed' status of the cap and, in certain circumstances, to initiate opening and closing of the valve 44 between the main tank 26 and the small tank 24. The status of the cap on the filler neck 4Ois communicated via a signal 48 to the ECU 46. Sensing systems like this are known, within the fuel caps of some vehicles, for example.

The level sensor 30 within the main tank 26 and the level sensor 28, colour sensor 32 and DIV sensor 34 within the small tank 24 are in communication with the ECU 46. More specifically, a signal (not shown) is transmitted from the level sensor 28 of the small tank 24 to the ECU 46 with a separate signal 52 transmitted from the level sensor 30 of the main tank 26 to the ECU 46, to provide information about the level of fluid 21 and aqueous urea solution 22 contained within the respective tanks 24 and 26. One or both of the level sensors 28, 30 may measure discrete points, sending a signal to the ECU 46 when the level of fluid in the tank 24, 26 passes the discrete points. In another possible embodiment, one or both of the level sensors 28, 30 may measure along a scale. The scale may be between 0 and 10, where a measuremenT of 0 is indicative of a substantially empty tank 24, 26 and a measurement of 10 is indicative of a substantially full tank 24,26, with signals sent continuously to the ECU 46 to indicate the levels of fluid in the tanks 24, 26.

The ECU 46 transmits a signal 54 to the colour sensor 32 and a signal 56 to the DIV sensor 34 within the small tank 24 to trigger them to initiate sensing. A signal 58 is subsequently sent from the colour sensor 32 to the ECU 46, and a separate signal 60 IS is sent from the DIV sensor 34 to the ECU 46, to provide information to the ECU 46 on the parameters of the fluid 21 contained in the small tank 24.

The ECU 46 is provided with a determination means, for example in the form of executable computer code, for receiving the signals 58 and 60 and, on the basis of pre-determined calibration data relating such signals to fluid type, is able to determine the type of fluid 21 in the small tank 24 and, if aqueous urea, the concentration of urea.

Based on the determination of fluid type, the ECU 46 computes the desired state of the valve 44 within the second conduit 42 and, in certain situations, sends a signal 62 to trigger the valve 44 to open or close accordingly. A Human Machine Interface (HMI) 64 (shown in Figure 4), generally positioned towards the front of the vehicle and located in the vehicle cabin, is also connected to the ECU 46. Signals 66 (shown in Figure 4) are sent from the ECU 46 to the HMI 64 to communicate key messages to the user of the vehicle so that they may take action accordingly.

Under normal operating conditions, the main tank 26 is at least partially filled with aqueous urea solution 22 with urea concentration between the limits of 32.5 +1-2%.

The level sensor 30 within the tank 26 detects a level of aqueous urea solution 22 above a predetermined threshold level required. At this stage the filler cap is closed, the small tank 24 is empty and the valve 44 is open.

The SCR system controls dosing of the aqueous urea solution 22 into the exhaust duct of the vehicle while the engine is running, reducing the volume of aqueous urea solution 22 in the main tank 26 until the predetermined threshold level is reached. As shown in Figure 3, when the predetermined threshold level is reached a signal 52 sent from the level sensor 30 in the main tank 26 to the ECU 46 triggers the ECU 46 to subsequently transmit a signal 66 (shown in Figure 4) to the HMI 64. The HMI 64 alerts the vehicle user that replenishment of the tank 26 is due. Figure 4 depicts a signal 62 transmitted from the ECU 46 to the valve 44, triggering it to close and seal off the second conduit 42. A signal 54 from the ECU 46 to the colour sensor 32 and a signal 56 from the ECU 46 to the DIV sensor 34 trigger the sensors to begin measuring parameters of the fluid 21 (shown in Figure 5).

A visual or audio alert from the HMI 64 prompts the vehicle user to feed 32.5% aqueous urea solution 22 (or AdBlue®) into the filler neck 40. As shown in Figure 5, IS on opening the cap of the filler neck 40 in the boot, the sensor on the filler neck 40 transmits a status signal 48 to the ECU 46, communicating that the cap is in an open' state. The ECU 46 then sends a signal to the LEDs 50 at the filler neck 40. In this example, an illuminated green LED 50 informs the user that the system 20 is in a ready-to-fill state and that they may proceed to feed in the aqueous urea solution 22.The user pours the fluid 21 into the filler neck 40, which passes through the first conduit 38 and into the small tank 24.

As shown in Figure 6, on reaching a predetermined upper threshold level of fluid 21, the level sensor 28 within the small tank 24 sends a signal to the ECU 46, triggering a signal to the LEDs 50. In this example, an illuminated red LED 50 informs the user that the system 20 is in a not-ready-to-fill state and that they should stop feeding the fluid 21 into the filler neck 40, preventing overflow of the fluid 21. The sensor at the cap of the filler neck 40 continues to transmit a signal 48 to the ECU 46 to indicate that the cap is in an "open state", preventing a signal 62 being sent from the ECU 46 to open the valve 44 to ensure that the valve between the small tank 24 and the main tank 26 remains closed.

There are two main scenarios for the following sequence of events, which depend on the nature of the fluid 21 which has been fed into the filler neck 40. The fluid 21 is either: an aqueous urea solution of correct concentration 22; or, an incorrect fluid 68.

The incorrect fluid 68 can be an aqueous urea solution of incorrect concentration, or a fluid which is not an aqueous urea solution.

II

Firstly, in the case that the user has poured the correct concentration of aqueous urea solution 22 into the filler neck 40, as shown in Figure 6, the colour sensor 32 and the DN sensor 34 measure parameters indicating a urea concentration falling within the limits of 32.5 +1-2%. In the event that the user has poured the correct solution 22 into the filler neck 40, and hence into the small tank 24, a signal 60 from the DIV sensor 34 and a signal 58 from the colour sensor 32 is communicated to the ECU 46. As shown in Figure 7, the ECU 46 subsequently sends a signal 62 to the valve 44, triggering the valve 44 to open. Once the valve 44 is open, the aqueous urea solution 22 is able to pass from the small tank 24, through the second conduit 42 and into the main tank 26.

In this example, since the small tank 24 is of reduced volume compared to the main tank 26, the main tank 26 is only partially filled with the correct aqueous urea solution is 22 at this stage. The ECU sends a signal (not shown) to trigger illumination of the LEDs 50 to indicate to the user that they should continue to pour the aqueous urea solution 22 into the tiller neck 40. In one embodiment of the invention, on reaching a certain volume of solution 22 within the main tank 26, the level sensor 30 sends a signal (not shown) to the ECU 46. This then transmits a signal (not shown) to the LEDs 50 which are illuminated to indicate to the user that they should stop feeding aqueous urea solution 22 into the filler neck 40.

Secondly, in the case that the user pours an incorrect fluid 68 into the filler neck 40, this again passes through the first conduit 38 and into the small tank 24, until the tank 24 is substantially full. In this example the incorrect fluid is a coolant. Referring to Figure 8, as previously, a signal 48 from the sensor at the tiller neck 40 to the ECU 46 communicates the open" state of the cap and the LEDs 50 indicate that the user should stop feeding the incorrect tluid 68 into the filler neck 40 on reaching a required level.

In this case, the parameter readings transmitted to the ECU 48 via the signal 58 from the colour sensor 32 and the signal 60 from the DIV sensor 34 detect that the incorrect fluid 68 does not exhibit the properties of an aqueous urea solution 22 of 32.5 +1-2% urea concentration. The ECU 46 sends a signal 66 to the HMI 64 to alert the user to the fact that the incorrect fluid 68 is not the correct specification and the red LED 50 stays illuminated. No signal is transmitted to the valve actuator 44 to trigger it to open, and so the valve actuator 44 remains closed such that no fluid 68 is transferred from the small tank 24 to the large tank 26 through the second conduit 42.

Referring to Figure 9, at this stage the small tank 24 can be drained by opening the drain valve 36. Relative to the prior art, this is a much more straightforward process for removing the incorrect fluid 68 from the system 20 and the vehicle user is able to perform this operation themselves, reducing the time and financial repercussions of feeding in an incorrect fluid 68.

A further benefit of the system 20 is that it allows for detection of issues prior to the engine being started, preventing the incorrect fluid 68 from progressing into the exhaust stream. This reduces the potential for blockages and damage to the components of the SCR system.

Is Referring to Figure 10, the user also has the option to fill the main tank 26 prior to the level of aqueous urea solution 22 within the main tank 26 falling below the predetermined threshold level. In this case, the user opens the cap at the filler neck 40, triggering a signal 48 to the ECU 46, communicating that the cap is in an open' state. A signal 62 is then transmitted from the ECU 46 to the valve 44, triggering it to close and seal off the second conduit 42. A separate signal 54, from the ECU 46 to the colour sensor 32 and a signal 56 from the ECU 46 to the DIV sensor 34 trigger the sensors to begin sensing. As previously described, a number of LEDs 50 may then prompt the user to begin pouring in the fluid 21.

In another embodiment of the invention, it is only opening of the cap at the filler neck which triggers closing of the valve 44, as described above and shown in Figure 10.

In another embodiment of the invention, it is only opening of the cap at the filler neck so 40 which triggers the colour sensor 32 and the DIV sensor 34 to begin sensing, as described above and shown in Figure 10.

In another embodiment of the invention (not shown), the small tank houses a refractive index sensor and a DN sensor for measuring fluid parameters.

In another embodiment of the invention (not shown), only one sensor is housed in the small tank for measuring fluid parameters. This sensor may be a single DIV sensor, since this can be used in isolation to detect the concentration of the fluid.

In another embodiment of the invention (not shown), the small tank is integrated into the main tank so that both are integrated in a separate package and separated by a wall between them. This may be an option where the main tank is in an accessible location within the vehicle, to allow the vehicle user to drain the small tank when incorrect fluid is detected. For example, the main tank may be a smaller separate container within the larger main tank volume.

In another embodiment of the invention, a signal from the cap at the filler neck to the ECU, indicating that the filler neck is in an open' state, results in activation of the colour sensor and the DIV sensor within the small tank so that they begin sensing. Is

It will be appreciated by a person skilled in the art that the invention could be modified to take many alternative forms to that described herein, without departing from the scope of the appended claims.

There may be provided a Fluid storage apparatus for storing a fluid for dosing into the exhaust gas stream of an internal combustion engine, the apparatus comprising: a main reservoir for storage of the fluid prior to dosing into the exhaust gas stream; a second reservoir, separate from the main reservoir, for temporary storage of the fluid prior to delivery to the main reservoir; a sensor arrangement for detecting at least one parameter of the fluid within the second reservoir; means for determining a fluid type based on the at least one parameter; and a valve means for controlling communication between the main reservoir and the second reservoir.

In an embodiment, the valve arrangement is operable in response to the determination of the fluid type.

Such operation may be so as to prevent communication between the second reservoir and the main reservoir in the event that the fluid does not correspond to an expected fluid type, or may be so as to enable communication if the fluid does correspond to an expected fluid type.

Further aspects of the present invention are set out in the following numbered Clauses: Clause 1. Fluid storage apparatus for storing a fluid for dosing into the exhaust gas IS stream of an internal combustion engine, the apparatus comprising: a main reservoir for storage of the fluid prior to dosing into the exhaust gas stream; a second reservoir, separate from the main reservoir, for temporary storage of the fluid prior to delivery to the main reservoir; a sensor arrangement for detecting at least one parameter of the fluid within the second reservoir; a determination module for determining a fluid type based on the at least one parameter; and a valve arrangement for controlling communication between the main so reservoir and the second reservoir and corresponding to a ready-to-fill state for the apparatus in which fluid communication between the main reservoir and the second reservoir is closed and a not-ready-to-fill state for the apparatus in which fluid communication between the main reservoir and the second reservoir is open; wherein the valve arrangement is operable in response to the determination of the fluid type so as to prevent communication between the second reservoir

IS

and the main reservoir in the event that the fluid does not correspond to an expected fluid type.

Clause 2. Fluid storage apparatus according to Clause 1 wherein the second reservoir is detached from the main reservoir in a separate housing.

Clause 3. Fluid storage apparatus according to Clause 1 wherein the second reservoir is integrated with or located within the main reservoir.

Clause 4. Fluid storage apparatus according to Clause 1 wherein the sensor arrangement includes a density and viscosity (D/V) sensor so as to provide an indication of the fluid type.

Clause 5. Fluid storage apparatus according to Clause 4 wherein the sensor arrangement includes a sensor configured to determine the colour of the fluid so as to provide an indication of the fluid type.

Clause 6. Fluid storage apparatus according to Clause 4 wherein the sensor arrangement includes a sensor configured to determine the refractive index of the fluid so as to provide an indication of the fluid type.

Clause 7. Fluid storage apparatus according to Clause 1 wherein the expected fluid type is an aqueous urea solution.

Clause 8. Fluid storage apparatus according to Clause 7 wherein the aqueous urea solution has a urea concentration within the range of 32.5 +1-2%.

Clause 9. Fluid storage apparatus according to Clause 1 wherein the main reservoir is provided with a main level sensor for monitoring the level of fluid stored therein.

Clause 10. Fluid storage apparatus according to Clause 1 wherein the second reservoir is provided with a second level sensor for monitoring the level of fluid stored therein.

Clause 11. Fluid storage apparatus according to Clause 1 including a notification device configured to alert a user that the apparatus is in the ready-to-fill state in which the valve means is closed.

Clause 12. Fluid storage apparatus according to Clause 11 wherein the notification device includes at least one light emitting diode (LED).

Clause 13. Fluid storage apparatus according to Clause 12 including a first LED of a first colour to indicate the ready-to-fill state.

Clause 14. Fluid storage apparatus according to Clause 13 including a including a second LED of a second colour to indicate that the main reservoir and/or the second reservoir are full.

Clause 15. Fluid storage apparatus according to Clause 13 wherein the second LED is configured to indicate the not-ready-to-fill state.

Clause 16. Fluid storage apparatus according to Clause 1 wherein the sensor arrangement is operable to determine the at least one parameter of the fluid only when the apparatus is in the ready-to-fill state.

Clause 17. Fluid storage apparatus according to Clause 1 including a drain for evacuation of the second reservoir in the event that the fluid in the second reservoir does not correspond to the expected fluid type.

Clause 18. A vehicle comprising the fluid storage apparatus according to Clause 9, further comprising a notification device configured to alert the vehicle user that the level of fluid in the main reservoir is less than a predetermined threshold level so as to prompt the user to fill the main reservoir with fluid.

Clause 19. A vehicle comprising the fluid storage apparatus according to Clause 1.

Clause 20. A method for filling a main reservoir with fluid for dosing into the exhaust gas stream of an internal combustion engine, the method comprising: temporarily storing the fluid in a second reservoir prior to delivery to the main reservoir; detecting at least one parameter of the fluid within the second reservoir; determining a fluid type based on the at least one parameter; and controlling fluid communication between the main reservoir and the second reservoir in response to the determination of the fluid type, a ready-to-fill state corresponding to fluid communication between the main reservoir and the second reservoir being closed and a not-ready-to-f ill state corresponding to fluid communication between the main reservoir and the second reservoir being open, so as to prevent IS communication between the second reservoir and the main reservoir in the event that the fluid does not correspond to an expected fluid type.

Clause 21. The method according to Clause 20 comprising monitoring the level of fluid in the main reservoir and alerting the user when the level falls below a predetermined threshold level.

Clause 22. The method according to Clause 21 comprising controlling a valve arrangement to open and close fluid communication between the main reservoir and the second reservoir.

Clause 23. The method according to Clause 20 comprising alerting the user of the ready-to-fill state, in which the fluid communication between the main reservoir and the second reservoir is closed.

Clause 24. The method according to Clause 20 comprising detecting at east one parameter of the fluid only when the apparatus is in the ready-to-fill state.

Clause 25. The method according to Clause 24 comprising detecting the density and viscosity of the fluid to determine the fluid type.

IS

Clause 26. The method according to Clause 25 comprising detecting the colour of the fluid to determine the fluid type.

Clause 27. The method according to Clause 25 comprising detecting the refractive index of the fluid to determine the fluid type.

Clause 28. The method according to Clause 20 comprising alerting the user in the event that the fluid in the second reservoir does not correspond to the expected fluid type.

Clause 29. The method according to Clause 20 comprising draining the second reservoir in the event that the fluid in the second reservoir does not correspond to the expected fluid type.

Clause 30. The method according to Clause 20 comprising opening fluid communication between the main reservoir and the second reservoir in the event that the fluid in the second reservoir does correspond to the expected fluid type.

Clause 31. The method according to Clause 20 wherein the expected fluid is an aqueous urea solution.

Clause 32. The method according to Clause 31 wherein the aqueous urea solution has a urea concentration within the range of 32.5 +/-5%.

Claims

CLAIMS1. Fluid storage apparatus for storing a fluid for dosing into the exhaust gas stream of an internal combustion engine, the apparatus comprising: a main reservoir for storage ol the fluid prior to dosing into the exhaust gas stream; a second reservoir, separate from the main reservoir, for temporary storage of the fluid prior to delivery to the main reservoir; a sensor arrangement for detecting at least one parameter of the fluid within the second reservoir; means for determining a fluid type based on the at least one parameter; and a valve means for controlling communication between the main reservoir and the second reservoir and corresponding to a ready-to-fill state for the apparatus in which fluid communication between the main reservoir and the second reservoir is closed and a not-ready-to-fill state for the apparatus in which fluid communication between the main reservoir and the second reservoir is open; wherein the valve means is operable in response to the determination of the fluid type so as to prevent communication between the second reservoir and the main reservoir in the event that the fluid does not correspond to an expected fluid type.
2. The fluid storage apparatus of claim 1 wherein the second reservoir is detached from the main reservoir in a separate housing.
3. The fluid storage apparatus of claim 1 wherein the second reservoir is integrated with or located within the main reservoir.
4. The fluid storage apparatus of claim 1 wherein the sensor arrangement includes a density and viscosity (D/V) sensor so as to provide an indication of the fluid type.
5. The fluid storage apparatus of claim 4 wherein the sensor arrangement includes a sensor for determining the colour of the fluid so as to provide an indication of the fluid type.S
6. The fluid storage apparatus of claim 4 wherein the sensor arrangement includes a sensor configured to determine the refractive index of the fluid so as to provide an indication of the fluid type.
7. The fluid storage apparatus of any of the preceding claims wherein the expected fluid type is an aqueous urea solution.
8. The fluid storage apparatus of claim 7 wherein the aqueous urea solution has a urea concentration within the range of 32.5 +1-2%.
9. The fluid storage apparatus of any of the preceding claims wherein the main reservoir is provided with a main level sensor for monitoring the level of fluid stored therein.
10. The fluid storage apparatus of any of the preceding claims wherein the second reservoir is provided with a second level sensor for monitoring the level of fluid stored therein.
11. The fluid storage apparatus of any of the preceding claims including means for alerting a user that the apparatus is in the ready-to-fill state in which the valve means is closed.
12. The fluid storage apparatus of claim 11 wherein the means for alerting includes at least one light emitting diode (LED).
13. The fluid storage apparatus of claim 12 including a first LED of a first colour to indicate the ready-to-fill state.
14. The fluid storage apparatus as claimed in claim 13 including a second LED of a second colour to indicate that the main reservoir and/or the second reservoir are full.
15. The fluid storage apparatus as claimed in claim 13 or claim 14 wherein the second LED is configured to indicate the not-ready-to-fill state.
16. The fluid storage apparatus of any of the preceding claims wherein the sensor arrangement is operable to determine the at least one parameter of the fluid only when the apparatus is in the ready-to-fill state.S
17. The fluid storage apparatus of any of the preceding claims including a drain means for evacuation of the second reservoir in the event that the fluid in the second reservoir does not correspond to the expected fluid type.
18. A vehicle comprising the fluid storage apparatus as claimed in claim 9, further comprising means for alerting the vehicle user that the level of fluid in the main reservoir is less than a predetermined threshold level so as to prompt the user to fill the main reservoir with fluid.
19. A vehicle comprising the fluid storage apparatus as claimed in any of claims ito 18.
20. A method for filling a main reservoir with fluid for dosing into the exhaust gas stream of an internal combustion engine, the method comprising: temporarily storing the fluid in a second reservoir prior to delivery to the main reservoir; detecting at least one parameter of the fluid within the second reservoir; determining a fluid type based on the at least one parameter; and controlling fluid communication between the main reservoir and the second reservoir in response to the determination of the fluid type, a ready-to-fill state corresponding to fluid communication between the main reservoir and the second reservoir being closed and a not-ready-to-f ill state corresponding to fluid communication between the main reservoir and the second reservoir being open, so as to prevent communication between the second reservoir and the main reservoir in the event that the fluid does not correspond to an expected fluid type.
21. The method of claim 20 comprising monitoring the level of fluid in the main reservoir and alerting the user when the level falls below a predetermined threshold level.S
22. The method of claim 21 comprising controlling a valve means to open and close fluid communication between the main reservoir and the second reservoir.
23. The method of any of claims 20 to 22 comprising alerting the user of the ready-to-fill state, in which the fluid communication between the main reservoir and the second reservoir is closed.
24. The method of any of claims 20 to 23 comprising detecting at east one 16 parameter of the fluid only when the apparatus is in the ready-to-fill state.
25. The method of claim 24 comprising detecting the density and viscosity of the fluid to determine the fluid type.
26. The method of claim 25 comprising detecting the colour ol the fluid to determine the fluid type.
27. The method of claim 25 comprising detecting the refractive index of the fluid to determine the fluid type.
28. The method of any of claims 20 to 27 comprising alerting the user in the event that the fluid in the second reservoir does not correspond to the expected fluid type.
29. The method of any of claims 20 to 28 comprising draining the second reservoir in the event that the fluid in the second reservoir does not correspond to the expected fluid type.
30. The method of any of claims 20 to 29 comprising opening fluid communication between the main reservoir and the second reservoir in the event that the fluid in the second reservoir does correspond to the expected fluid type.
31. The method of any of claims 20 to 29 wherein the expected fluid is an aqueous urea solution.
32. The method of claim 31 wherein the aqueous urea solution has a urea concentration within the range ol 32.5 +1-5%.