Exhaust gas treatment fluid system

Abstract

Exhaust gas treatment fluid system comprising: a tank housing (42) for storing an exhaust gas treatment fluid (44) comprising a suction port and a discharge port; a suction tube (52) having a first end positioned in the tank housing (42) and a second end connected to the suction port; and an elongated laminar flow device (70) attached to the discharge port such that exhaust gas treatment fluid (44) flows along its surfaces when the exhaust gas treatment fluid (44) is returned to the tank housing (42), the laminar flow device (70) having a non-circular cross-section.

Description

REGIONThe present disclosure is directed to an exhaust treatment fluid system.BACKGROUNDThis section contains background technical information related to the present disclosure without necessarily requiring that it be the state of the art.Exhaust aftertreatment systems may meter an exhaust treatment fluid into the exhaust stream to promote chemical reactions that remove NOx from the exhaust stream. The exhaust treatment fluid may be stored in a storage tank in communication with a dosing module that doses the exhaust treatment fluid into the exhaust system. The storage tank may include various sensors to determine a temperature of the fluid level, a fluid level in the tank, and a concentration of the fluid in the tank. When the exhaust treatment fluid is a urea solution, the solution may freeze at cold temperatures. To prevent the urea solution from freezing in the dosing module, the dosing module may be flushed and the unused urea solution returned to the tank. After a flushing, the system must generally be pre-filled before the dosing of the urea solution can be resumed. During the pre-filling process, the urea solution is guided from the tank through the metering module and back to the tank. The return of the urea solution to the tank may occasionally interfere with the operation of the various sensors in the tank.EP 2 573 350 A1 discloses an SCR sensor that does not impair measurement accuracy of a quality sensor even when a remaining amount of a urea container is reduced. A quality sensor is installed between a minimum liquid level S and a lower portion of a urea tank; a drop pipe is installed from a ceiling portion of the urea tank to an upper space in the urea tank 105; a support is installed from the bottom portion to the ceiling portion of the urea tank; the quality sensor and the drop pipe are integrated by the support; and a bubble diffusion region B caused by the urea aqueous solution dropping from the drop pipe is from a sensitive region f of the quality sensor.JP 2005-299441 A discloses a urea water storage device. With respect to a storage device for urea water as a reducing agent to be added to a selective reduction type catalyst for reducing NOx for purification, a urea water concentration sensor is disposed in a tank for storing urea water, and the periphery of the urea water concentration sensor is surrounded by a container-like bubble foam protector, and the urea water concentration sensor is covered with a foam trap filter formed of a hydrophilic raw material inside the foam protector.DE 601 03 802 T2 discloses a fuel pressure shock absorber comprising a channel which conducts fuel during operation and an elongate fluid damping element which is inserted into this channel and has a wall which runs along a longitudinal axis, and is characterised in that this wall has at least one bulge which is directed radially away from the axis and extends along this axis, this bulge absorbing pressure shocks which are present in a fluid flow during operation.SUMMARYThis section contains a general summary of the invention and is not a comprehensive disclosure of its entire scope or all of its features.An exhaust treatment fluid system includes a tank housing for storing an exhaust treatment fluid. An intake manifold includes a first end positioned within the housing and a second end in communication with an intake manifold of the housing. An elongated laminar flow device is mounted on an outlet port of the housing such that exhaust treatment fluid flows along its surfaces when the exhaust treatment fluid is returned to the tank housing. The laminar flow device has a non-circular cross section.An exhaust treatment fluid system includes a tank housing for storing an exhaust treatment fluid. The tank is adapted for mounting on a motor vehicle. An intake pipe is positioned in the tank. The exhaust treatment fluid system also includes an injector including an inlet in fluid communication with the intake manifold and an outlet. An elongated laminar flow device is positioned within the tank housing and is in fluid communication with the outlet. The exhaust treatment fluid flows through the outlet and is directed to flow across an outer surface of the laminar flow device.Further areas of applicability will become apparent in the course of the following description. The description and specific embodiments in this summary are for illustrative purposes only and are not intended to limit the scope of the present disclosure.FIGURESThe figures described herein are intended to illustrate only selected embodiments and not all implementations, and not to limit the scope of the present disclosure. FIG. 1 is a schematic diagram of an exhaust system according to a principle of the present disclosure; FIG. 2 is a cross-sectional view of a reagent tank according to a principle of the present disclosure; FIG. 3 is an exploded perspective partial view of the reagent tank illustrated in FIG. 2 ;FIGS. 4 to 9 are cross-sectional views of a laminar flow device and an exhaust pipe according to a principle of the present disclosure; FIG. 10 is a cross-sectional perspective view of a mounting plate including a suction tube, an exhaust tube, and a laminar flow device according to a principle of the present disclosure. FIG. 11 is a cross-sectional view of a reagent tank according to a principle of the present disclosure; FIG. 12 is a cross-sectional view of a reagent tank according to a principle of the present disclosure; FIG. 13 is a fragmentary perspective view of a sensor assembly according to another principle of the present disclosure;FIGS. 14 and 15 are perspective views of a shield in conjunction with the sensor assembly illustrated in FIG. 13. FIG. 16 is an exploded perspective view of an alternative shield made in accordance with the teachings of the present disclosure; FIG. 17 is a flow diagram illustrating a control scheme associated with the sensors of an exhaust treatment fluid system; FIG. 18 is a flow diagram illustrating an alternative control scheme for the exhaust treatment fluid system; and FIG. 19 is another flow diagram illustrating another alternative control scheme associated with the sensors of an exhaust treatment fluid system.Corresponding reference numerals indicate corresponding parts in the different Figures.DETAILED DESCRIPTIONThe following is a more comprehensive description of exemplary embodiments with reference to the accompanying figures.FIG. 1 is a schematic illustration of an exhaust system 10 in accordance with the present disclosure. The exhaust system 10 may include at least one internal combustion engine 12 in communication with a fuel source (not shown) that, when exhausted, generates exhaust gases that are discharged into an exhaust passage 14 having an exhaust aftertreatment system 16. The internal combustion engine 12 may be followed by an exhaust treatment component 18, which may be a DOC component, a DPF component, or an SCR component 20, as shown. Although not required by the present disclosure, the exhaust aftertreatment system 16 may further include components such as a thermal boost device or a burner 17 to increase a temperature of the exhaust gas as it flows through the exhaust passage 14. Increasing the temperature of the exhaust gas is beneficial to achieve light-off (light-off) of the catalyst in the exhaust treatment component 18 during cold weather and when starting the internal combustion engine 12, and to initiate regeneration of the exhaust treatment component 18 when the exhaust treatment component 18 is a DPF.To assist in reducing emissions produced by the internal combustion engine 12, the exhaust aftertreatment system 16 may include a dosing module 22 for periodically dosing an exhaust treatment fluid into the exhaust stream. As seen in FIG. 1, the dosing module 22 may be disposed upstream of the exhaust treatment component 18 and is operable to inject an exhaust treatment fluid into the exhaust stream. In this regard, the dosing module 22 includes an injector having an inlet in fluid communication with a reagent tank 24 and a pump 26 via an inlet line 28 to dose an exhaust treatment fluid, such as diesel fuel or urea, into the exhaust passage 14 upstream of the exhaust treatment component 18. The injector of the dosing module 22 may also include an outlet in fluid communication with the reagent tank 24 via return line 30. The return line 30 allows exhaust treatment fluid that has not been dosed into the exhaust stream to be returned to the reagent tank 24. the flow of exhaust treatment fluid through inlet line 28, dosing module 22, and return line 30 also helps to cool the injector of the dosing module 22 so that the dosing module 22 does not overheat. The dosing module 22 may be configured to include a cooling jacket that circulates a coolant around the dosing module 22 to cool it.The amount of exhaust treatment fluid required to effectively treat the exhaust flow may also depend on the size of the internal combustion engine 12. In this regard, large diesel engines used in locomotives, marine applications, and stationary applications may have exhaust flow rates that exceed the capacity of a single dosing module 22. Although only a single dosing module 22 is shown for urea dosing, it should be appreciated that the present disclosure contemplates multiple dosing modules 22 for urea injection.The amount of exhaust treatment fluid required to effectively treat the exhaust flow may also vary depending on the load, engine speed, exhaust temperature, exhaust volumetric flow rate, fuel injection times, desired NO x- reduction, barometric pressure, relative humidity, exhaust gas recirculation (EGR) rate, and engine cooling temperature. A NO x- sensor or meter 32 may be positioned downstream of the SCR 20. The NO x- sensor 32 is operable to output to an engine control unit 34 a signal indicative of the exhaust NO x- content. All or some of the engine operating parameters may be provided from the engine control unit 34 to an exhaust aftertreatment controller 36 via an engine / vehicle data bus. The control device 36 could also be provided as part of the engine control unit 34. Exhaust temperature, exhaust gas volume flow and exhaust gas back pressure, as well as other vehicle operating parameters, may be measured by corresponding sensors, as shown in FIG. 1.The exhaust gas treatment system control unit 36 can also monitor a temperature of the exhaust gas treatment fluid as a parameter. To monitor a temperature of the exhaust treatment fluid, the reagent tank 24 may include an internally disposed temperature sensor 40. As best seen in FIG. 2, the reagent tank 24 may include a tank housing 42. The tank housing 42 may be formed from materials such as polyethylene, polypropylene, polystyrene, aluminum, steel, or any other type of material suitable for storing an exhaust treatment reagent fluid 44, such as urea. To refill tank 24 with an exhaust treatment fluid, tank 24 may include an inlet 46 defined by a threaded stub 48 that may receive a removable cap 50 that is threaded to match the thread of stub 48, as is known in the art.In the tank housing 42, a suction pipe 52 and an outlet pipe 54 may be provided in pairs. The intake manifold 52 is in communication with the downstream pump 26 such that upon activation of the pump 26, the urea exhaust treatment fluid 44 is drawn from the tank 24 into the intake conduit 28. As noted above, the inlet conduit 28 is in communication with the dosing module 22 to provide urea exhaust treatment fluid to the exhaust flow. If the urea exhaust treatment fluid 44 is not dosed into the exhaust gas flow, the urea exhaust treatment fluid 44 can return to the tank 24 via return line 30. The return conduit 30 is in communication with the outlet pipe 54 The suction pipe 52 and the outlet pipe 54 may each be secured to a bulkhead or mounting plate 55 which may be seated on top of the tank 24 in the tank 24. The bulkhead plate may sealingly engage a single opening (not shown) extending through the tank housing 42.To monitor the amount of urea exhaust treatment fluid 44 in the tank 24, a fluid level indicator 56 may be connected to the outlet pipe 54. In the illustrated embodiment, the fluid level indicator 56 may include an ultrasonic sensing device 58 that emits ultrasonic waves 60. The ultrasonic sensing device 58 may be positioned on a support member 59 connected to the suction pipe 52. Ultrasonic waves 60 may be emitted from the ultrasonic sensing device 58 to a surface 62 of the exhaust treatment fluid 44, which are then reflected back from the surface 62 to the ultrasonic sensing device 58. The time required for ultrasonic waves 60 to be reflected back from surface 62 and return to ultrasonic sensing device 58 may be measured by controller 36 so as to determine an amount of fluid 44 remaining in tank 24. Ultrasonic sensor device 58 is connected to control unit 36.An exhaust treatment fluid heater 64 may also be positioned in the tank 24. The fluid heater 64 is configured to increase a temperature of the exhaust treatment fluid 44, particularly during cold weather conditions, when the exhaust treatment fluid 44 may freeze. The fluid heater 64 can be, in particular, a resistance heater or can be designed such that a cooling fluid for the engine can flow through it. The fluid heater 64 does not necessarily need to operate continuously during operation of the internal combustion engine 12. Instead, the fluid heater 64 communicates with the controller 36 such that the fluid heater 64 may be turned on as needed. In this case, a temperature of the exhaust gas treatment fluid 44 can be transmitted from the temperature sensor 40 to the control unit 36. If the measured temperature is too low, the controller 36 may command activation of the fluid heater 64 to warm up or thaw the exhaust treatment fluid 44.The temperature sensor 40 may be positioned in the tank 24 at any location suitable for properly determining a temperature of the exhaust treatment fluid 44. The temperature sensor 40 may be attached to the inner wall 66 of the housing 42, for example. Alternatively, temperature sensor 40 may be attached to suction tube 52 or exit tube 54.The tank 24 may also include a concentration sensor 68. The concentration sensor 68 may be attached to the inner wall 66, or may be attached to the suction tube 52, exit tube 54, or other structure without departing from the scope of the present disclosure. The concentration sensor 68 is operable to determine a concentration of the urea exhaust treatment fluid 44, which may be particularly advantageous for determining whether a different fluid (e.g., water) has entered the tank 24 in addition to the urea exhaust treatment fluid 44. If a concentration of the exhaust gas treatment fluid 44 determined by the control unit 36 exceeds or falls below a predefined value, the control unit 36 can output an error flag which prevents a metering process of the metering module 22 or the operation of the internal combustion engine 12 until a correct concentration of fluid 44 is reached. Alternatively, the control device 36 can adjust the dosage in order to take account of the present concentration.To determine a concentration of the exhaust treatment fluid 44, the concentration sensor 68 may be an ultrasonic sensor operable to emit ultrasonic waves 61 into the exhaust treatment fluid. The scope of the present disclosure encompasses other types of non-ultrasonic sensors. In the illustrated exemplary embodiment, the concentration sensor 68 may be disposed proximate the ultrasonic sensing device 58 and emit ultrasonic waves 61 that are then reflected by the ultrasonic sensing device 58. Alternatively, a reflecting member (not shown) may be disposed between the concentration sensor 68 and the ultrasonic sensing device 58 to reflect the ultrasonic waves 61. Another alternative is that the concentration sensor 68 faces the inner wall 66 and emits ultrasonic waves 61 reflected therefrom. Nevertheless, the controller 36 may determine a concentration of the exhaust treatment fluid 44 based on the velocity of the ultrasonic waves 61. Although the fluid level indicator 56 and the concentration sensor 68 in the tank 24 are shown as distinct components, it should be appreciated that a single sensor (e.g., an ultrasensor device 58) may be used for level measurement and concentration measurement without departing from the scope of the present disclosure.When the internal combustion engine 12 or the exhaust aftertreatment system 16 is not operating (i.e., when no exhaust treatment fluid is dosed into the exhaust stream), exhaust treatment fluid 44 present in the dosing module 22, intake line 28, return line 30, and pump 26 may freeze at cold temperatures. To prevent the exhaust treatment fluid 44 from freezing in the dosing module 22, the inlet line 28, the return line 30, and the pump 26, the pump 26 can be operated in such a way that it operates in the opposite direction for flushing these elements. After purging, the pump 26 may be pre-filled to engage the inlet conduit 28 and the dosing module 22 before dosing the exhaust treatment fluid 44 into the exhaust stream. During pre-filling, the unused exhaust treatment fluid 44 flows back from the dosing module 22 to the tank 24 via the return line 30.In addition to unused exhaust treatment fluid 44, unused exhaust treatment fluid 44 may also contain air that was previously in tank 24. The air present in unused exhaust treatment fluid 44 may result in bubbling when the air is returned to tank 24. These bubbles can then rise to surface 62 through perforations 57 formed in the exit tube 54 and remain on surface 62 for a period of time that becomes foamy. The bubbles and foamy surface 62 are not conducive to determining a proper fluid level in the tank 24 by the ultrasonic sensing device 58 or a proper concentration by concentration sensor 68. The bubbles may also interfere with the concentration sensor 68 by possibly remaining suspended in the exhaust treatment fluid 44 and causing a density change in the exhaust treatment fluid 44 that is monitored by the concentration sensor 68.To prevent the formation of bubbles during the return of the exhaust treatment fluid 44 to the tank 24, a laminar flow device 70 may be disposed in the outlet pipe 54. As best shown in Figure 3, the laminar flow device 70 may be an elongated member having a length substantially the same as the length of the exit tube 54. The laminar flow device 70 has a generally non-circular cross-section and has a diameter less than the diameter of the exit tube 54 so that the laminar flow device 70 can fit within the exit tube 54. The non-circular cross-section of the laminar flow device allows for the presence of an air gap 72 (FIG. 4 ) between the laminar flow device 70 and an inner surface 74 of the exit tube 54.The exhaust treatment fluid 44 tends to flow along the surfaces 76 of the laminar flow device 70, while return air may flow in the air gap 72 provided between the laminar flow device 70 and an inner surface 74. Air flowing in the air gap 72 may be expelled through perforations 57 into the tank 24 before flowing below the level 62 of fluid 44. In this way, the occurrence of bubbles that can interfere with the ultrasonic sensing device 58 is prevented or at least substantially minimized. Although the use of a laminar flow device 70 in cooperation with the outlet pipe 54 has been described in the aforementioned embodiment, it should be understood that the present disclosure is not to be limited thereto. In this regard, embodiments are also included in the present disclosure wherein a laminar flow device 70 is used in place of the exit tube 54.Although the laminar flow device 70 is shown in FIG. 4 as having a star-shaped cross-section, the present disclosure is not to be limited thereto. The laminar flow device 70 may comprise any non-circular cross-section known to those skilled in the art. Figure 5 illustrates the laminar flow device 70 having a triangular cross-section. Figure 6 shows the laminar flow device 70 having a Y-shaped cross section. FIG. 7 shows a planar laminar flow device 70, and FIG. 8 shows the laminar flow device 70 having a cross-shaped cross section. Fig. 9 shows the laminar flow device 70 having a square cross section.As best seen in FIG. 10, the laminar flow device 70 may include a threaded end 78. The threaded end 78 may correspond to a thread 80 formed in an opening 82 of the mounting plate 55. After the laminar flow device 70 has been screwed into the mounting plate 55, the outlet pipe 54 can be fitted around the laminar flow device. In the arrangement shown in FIG. 10, the outlet pipe 54 is press fit into a counterbore 83 of the mounting plate 55. Unlike the laminar flow device 70 that is threaded into the mounting plate 55, the suction pipe 52 may be press fit into an opening 84 of the mounting plate. Alternatively, the suction tube 52 and the aperture 84 may each include threads to secure the suction tube 52 to the aperture 84. In another embodiment, the laminar flow device 70 may be press fit into the exit tube 54.FIG. 10 also includes continuous contour line arrows describing the direction of flow of the urea when the pump is operated to supply pressurized fluid to the dosing module 22. Dashed contour line arrows indicate the direction of flow of air flowing in the system when pump 26 is operated in the purge mode to supply unused exhaust treatment fluid 44 to tank 24. Two openings 85a, 85b are paired near the mounting plate 55 to provide an air flow path from the tank 24 to the outlet pipe 54.Referring now to FIG. 11, another example embodiment of tank 24 is illustrated. Tank 24 includes an outlet pipe 54 configured to allow air to escape through perforations 57 formed in the pipe while allowing recirculated exhaust treatment fluid to flow along inner pipe surfaces. Here, the outlet pipe 54 may be formed in a zigzag configuration. Although a zig zag configuration is illustrated, it will be appreciated that the exit tube 54 may be helical or spiral without deviating from the scope of the present disclosure.In another exemplary embodiment of the present disclosure illustrated in FIG. 12, a protective shield or shield 86 may be disposed about the ultrasonic sensing device 58 and the concentration sensor 68. As indicated above, the concentration sensor 68 may be configured to emit ultrasonic waves 61 (FIG. 2 ) towards the ultrasonic sensing device 58, from which the ultrasonic waves are then reflected back towards the concentration sensor 68. If bubbles occur at locations near the concentration sensor 68 and the ultrasonic sensing device 58 formed by the recirculation of the exhaust treatment fluid 44 to the tank 24, improper concentration measurement may occur due to a change in the density of the exhaust treatment fluid and due to unnecessary reflections of the ultrasonic waves 61.The shield 86 may be attached to a bottom surface 88 of the tank 24 and circumferentially surrounds the ultrasonic sensing device 58 and the concentration sensor 68. This provides an area 90 defined by an interior of the shield 86 in which the ultrasonic sensing device 58 and the concentration sensor 68 may be disposed. The shield 86 has a height H that exceeds a location where the ultrasonic sensing device 58 and the concentration sensor 68 are positioned. This prevents bubbles from entering region 90 and interfering with ultrasonic sensing device 58 and concentration sensor 68. Although the shield 86 is shown secured to the bottom surface 88 of the tank 24, it should be understood that the present disclosure is not limited to such a configuration. In contrast, shield 86 may be attached to other elements such as suction tube 52 or may be attached to support member 59 as long as bubbles are prevented from entering space 92 between ultrasonic sensing device 58 and concentration sensor 68.Although not specifically shown in FIG. 12, it should be understood that the exit tube 54 may include a laminar flow device 70. That is, tank 24 may be configured to include both shield 86 and laminar flow device 70. Further, shield 86 is believed to include a plurality of perforations that allow exhaust processing fluid 44 to flow into region 90 while preventing bubble ingress.FIGS. 13-15 illustrate a portion of a sensor assembly 100 which may be disposed in the tank 24 as a structure separate from the inlet pipe 52 and outlet pipe 54. The sensor assembly 100 may be attached to any number of components, including the mounting plate 55, the tank 24, the suction tube 52, and / or the outlet tube 54. The housing body 102 may be molded of a plastic so that the first tube 104 is integrally formed with the second tube 106. A carrier 110 may be manufactured as a separate component and connected to the first tube 104 and second tube 106 or may be integrally molded to the housing body 102.When installed in the tank 24, the first tube 104 receives exhaust treatment fluid 44 via an opening 108 through the first tube 104. The second tube 106 receives wires 109 that are connected to the concentration sensor 68 and to other electrical elements that can be connected to the carrier 110. For example, it is provided that a temperature sensor 112 is mounted on the carrier 110. Another optional embodiment may include a heating element 114 connected to the carrier 110. The heating element 114 may be selectively turned on depending on the temperature of the exhaust treatment fluid 44 measured via temperature sensor 112. wires 109 and optionally one or more controllers may be positioned in the second tube 106.A shield 118 is detachably connected to the housing body 102. The shield 118 functions substantially similar to the shield 86 described above. the shield 118 is preferably a one-piece molded plastic lid snap-fit to the housing body 102. Other forms of attachment such as screws or interference fit are also included within the scope of the present disclosure. The shield 118 includes a continuous wall 120, a top 122, a first leg 124, and a second leg 126. An opening 128, substantially eight in shape, extends through the top 122 thereby permitting passage of the first tube 104 and the second tube 106. At one edge of the opening 128 is a notch 130 sized and arranged so that a protrusion projecting from the first tube 104 engages therein to prevent rotation of the shield 118 relative to the housing body 102. Apertures 132, 134 extend through the top 122 to allow air below the shield 118 to escape. A rib 138 connects the sidewall 120 to the top 122 thereby providing a predetermined stiffness to the shield 118. The predetermined stiffness is less than if a complete rigid structure were provided. Accordingly, opposing portions of the sidewall 120 identified by reference numerals 140a, 140b are flexible relative to each other and provide for the event of a volume increase occurring when exhaust treatment fluid 44 is frozen within the tank 24. A flexible shield 118 is provided that does not break when exposed to freezing exhaust treatment fluid 44 related forces.The shield 118 is made of a flexible material that allows temporary elastic deformation of the legs 124, 126, such that a first latching element 144 and a second latching element 146 are displaced from a position assumed in the free state and are guided past the carrier 110. After being guided past the carrier 110, the legs 124, 126 elastically return to their free state and position the latching element 144 and latching element 146 adjacent to the holding surface 148 of the carrier 110.The apertures 150, 152 extend through the wall 120 and allow exhaust treatment fluid 44 to flow through the shield 188 and flow to the concentration sensor 68. A portion of the fluid passing through the apertures 150, 152 may also flow into the first tube 104 via aperture 108. Another passage for exhaust treatment fluid is provided in a space 153 between an edge 154 of side wall 120 and a surface 158 of carrier 110. With this arrangement, one portion of edge 154 abuts a surface 160 of carrier 110, while another portion of edge 154 is spaced from carrier 110 to allow restricted fluid flow 44 from the main housing of tank 24 under shield 118. The openings 150, 152 and the gap 153 are sized to allow fluid flow, but to allow bubbles to pass only to a limited extent below the shield 118. The openings 132, 134 are also dimensioned in particular such that they are relatively small so that possible air inclusions can escape under the shield 118, while at the same time the penetration of bubbles is minimized. It should be appreciated that the snap-fit connection with inwardly encircling detents 144, 146 is exemplary only and other mechanisms for securing shield 118 to first tube 104, second tube 106, or carrier 110 are included within the scope of the present disclosure.Figure 16 illustrates an alternative shield 118a. Shield 118a is substantially similar to shield 118 except that a first half 168 is separable from a second half 170. A plurality of prongs 172 project from the first half 168. The prongs 172 are configured to snap into a plurality of receptacles 174 in the second half 170. When the prongs 172 are seated in the receptacles 174, the first half 168 is secured to the second half 170. The other features of shield 118a are substantially identical to those of shield 118. Similar features are identified by corresponding reference numerals, supplemented by the letter "a". By configuring the shield 118 aas a two-part arrangement, the production method can be simplified with regard to the configuration of the first tube 104, the second tube 106 and the carrier 110 and to the connection of these components to the shield 118 a.The exemplary embodiments described above help prevent bubbles generated during a purge / pre-fill cycle from interfering with the level sensor device 58 and the concentration sensor 68 when these sensors measure the level and concentration of the exhaust treatment fluid 44. However, if the tank 24 is not provided with the laminar flow device 70 or the shield 86, bubbling may interfere with these sensors 58 and 68. To further minimize the impact of interference on the sensors 58 and 68, the controller 36 may delay operation of the sensors 58 and 68 for a predetermined time after the pre-fill cycle is completed. For example, controller 36 may delay operation of sensors 58 and 68 for a period in the range of ten to twenty minutes. In such a case, bubbles from the pre-fill pass may dissolve to such an extent that they do not substantially interfere with either the ultrasonic sensing device 58 or the concentration sensor 68.Another alternative to delaying the operation of the sensors 58 and 68 after the end of the pre-fill cycle is to delay the sensors 58 and 68 for a predetermined period of time from the start of the pre-fill cycle. For example, as shown in FIG. 17, the pre-fill operation may be controlled by the controller 36 to begin at a "key on" condition 200. Priming the pump begins at block 210. A timer (timer) counts a certain amount of time in block 220 (e.g., five minutes). Knowing that the pre-fill event takes a certain amount of time to complete, the output of sensors 58 and 68 over the first predetermined period of time may be ignored until the counter shuts down at block 230 (e.g., fifteen to twenty five minutes). After the set time has elapsed, control continues to block 240. The controller evaluates the outputs of the sensors 58, 68 and determines whether new fault codes are to be sent according to standard instruction of operation based on the signals coming from the sensors 58, 68.FIG. 18 shows a flow chart for an alternative control scheme, which is substantially similar to the control already described with reference to FIG. 17. Correspondingly, similar elements are identified with corresponding reference numerals, each increased by 100. For example, "key on" block 300 is substantially similar to block 200. At block 315, an actual value of one of the sensors described above, such as concentration sensor 68 or ultrasonic sensing device 58, is compared to the last stored value of the same sensor. At block 320, the controller determines whether the difference between a recently detected sensor value and the last stored value exceeds a predetermined range of values. If so, the controller starts the timer and ignores the sensor outputs as described above. Once the timer is disabled, a recently detected sensor value is compared to the previous stored value at block 335. At block 340, control determines whether to send a new fault code warning based on the comparison performed at block 335. The control scheme set forth in FIG. 18 may be applied to one or more sensors in the exhaust treatment fluid storage tank as desired.FIG. 19 shows a flow chart for another alternative control scheme substantially similar to the control described with respect to FIG. 18. Correspondingly, similar elements are identified with corresponding reference numerals, each increased by 100. Block 415 differs from block 315 in that actual values of the concentration sensor 68 and of the ultrasonic sensor device 58 are here each compared with profile values of the corresponding sensor. At block 420, the controller determines whether the two determined actual values are outside their respective historical data-related value range. If so, a period of time begins to run in which the error codes are ignored. By implementing a control strategy in which the current measured values of both sensors must be outside the range of values, the probability of sending a wrong fault code warning is minimized. If, for example, only the data of the fill level sensor are used in the controller, a fault code warning may occur before "key on" at block 400 if the tank 24 is filled with exhaust gas treatment fluid by the vehicle driver. Referring again to FIG. 19, if the timer is turned off at block 430, the controller compares the current quality sensor and level sensor sensor sensor values to historical history values at block 435. If necessary, new error code alerts are sent at block 440.The foregoing description is for purposes of illustration and illustration. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but are interchangeable where appropriate and may be used in a selected embodiment, even if not specifically shown or described. For example, an alternative fluid level indicator 56a may be connected to the sensor assembly 100. As seen in FIG. 13, the fluid level indicator 56 aincludes a float 180 placed in the first tube 104. The float 180 remains in the first tube 104 at the surface of the exhaust treatment fluid. As mentioned above, the fluid may flow into the first tube 104 through apertures 150 in the shield 118 and through an aperture 108 passing through the wall of the first tube 104. The float 180 may be connected to a switch (not shown) or to a sensor that indicates the position of float 180 in the first tube 104. The switch or associated sensor is operable to output a signal indicative of the level of the exhaust treatment fluid in the tank 24. Many modifications are possible. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

An exhaust treatment fluid system comprising: a tank housing (42) for storing an exhaust treatment fluid (44) comprising a suction port and a discharge port; an intake manifold (52) having a first end positioned within the tank housing (42) and a second end in communication with the suction port; and an elongated laminar flow device (70) mounted on the discharge port such that exhaust treatment fluid (44) flows along surfaces thereof when the exhaust treatment fluid (44) is recirculated to the tank housing (42), wherein the laminar flow device (70) has a non-circular cross-section.The exhaust treatment fluid system of claim 1, further comprising an outlet pipe (54) positioned within the tank housing (42) and secured to the outlet port, wherein the laminar flow device (70) is positioned within the outlet pipe (54).The exhaust treatment fluid system of claim 1, wherein the outlet pipe (54) comprises an inner surface (74) and the non-circular cross-section of the laminar flow device (70) provides an air gap (72) between the surfaces of the laminar flow device (70) and the inner surface of the outlet pipe (54).The exhaust treatment fluid system of claim 1, wherein the cross section of the laminar flow device (70) is quadrangular.The exhaust treatment fluid system of claim 1, wherein the cross section of the laminar flow device (70) is triangular.The exhaust treatment fluid system of claim 1, wherein the cross section of the laminar flow device (70) is Y-shaped.The exhaust treatment fluid system of claim 1, wherein the cross-section of the laminar flow device (70) is cruciform.The exhaust treatment fluid system of claim 1, wherein the cross section of the laminar flow device (70) is star-shaped.The exhaust treatment fluid system of claim 1, wherein the cross section of the laminar flow device (70) comprises a planar surface.The exhaust treatment fluid system of claim 1, further comprising a sensor (58 / 68) for determining a fluid level of the exhaust treatment fluid (44) and / or a concentration of the exhaust treatment fluid (44), wherein the sensor (58 / 68) is positioned within the tank housing 42.The exhaust treatment fluid system of claim 10, further comprising a controller (36) that determines whether to send an error code warning based on a signal output from the sensor (58 / 68), wherein the controller (36) ignores the signal for a predetermined amount of time before determining whether to send the error code warning.The exhaust treatment fluid system of claim 11, wherein the predetermined time period begins when a pump (26) pumping the exhaust treatment fluid (44) begins priming.The exhaust treatment fluid system of claim 11, wherein the controller (36) compares the signal output of the sensor (58 / 68) to a previously stored value and determines whether to begin ignoring the signal based on the comparison of the signal to the previously stored value.The exhaust treatment fluid system of claim 10, further comprising a further sensor positioned in the tank (24) and determining the other of the fluid level and concentration of the exhaust treatment fluid.The exhaust treatment fluid system of claim 14, wherein the controller (36) compares a signal output of the sensor (58 / 68) and a signal output of the further sensor to previously stored values and determines whether to start a timer during which the signals are ignored based on the comparison of the signals to the previously stored values.The exhaust treatment fluid system of claim 15, wherein the signals from the sensor (58 / 68) and the further sensor are ignored only if both signals are outside the desired range of values when compared to the previously stored values.The exhaust treatment fluid system of claim 14, further comprising a temperature sensor (112) positioned proximate to the sensor (58 / 68) and the further sensor.The exhaust treatment fluid system of claim 1, further comprising a bulkhead plate (55) sealingly engaging the tank housing (42), the suction tube and the laminar flow device (70) being secured to the bulkhead plate (55).The exhaust treatment fluid system of claim 1, wherein the laminar flow device (70) comprises a threaded (80) end (78) coupled to the tank (24) and a free opposite end.The exhaust treatment fluid system of claim 1, wherein the laminar flow device (70) is positioned in a non-vertical orientation.An exhaust treatment fluid system comprising: a tank housing (42) for storing an exhaust treatment fluid (70), the tank housing (42) adapted to be mounted to a vehicle; an intake manifold (52) positioned in the tank housing (42); an injector comprising an inlet in fluid communication with the intake manifold (52) and an outlet; an elongated laminar flow device (70) positioned in the tank housing (42) and in fluid communication with the outlet, wherein the exhaust treatment fluid (44) flows through the outlet and is directed to flow across an outer surface of the laminar flow device (70).The exhaust treatment fluid system of claim 21, further comprising an outlet pipe (54) positioned in the tank housing (42), in fluid communication with the outlet and surrounding the laminar flow device (70), wherein the exhaust treatment fluid (44) flowing through the outlet also flows through the outlet pipe (54).The exhaust treatment fluid system of claim 22, wherein the suction tube (52) and the exhaust tube (54) each comprise open ends spaced from an inner surface of the tank housing (42).The exhaust treatment fluid system of claim 22, wherein the laminar flow device (70) extends over an overall length of the exit pipe (54).The exhaust treatment fluid system of claim 22, further comprising a pump (26) coupled to the intake manifold (52) and supplying pressurized exhaust treatment fluid (44) from the tank housing (42) to the injector when driven in a first direction, the pump (26) being drivable in an opposite direction to flush the exhaust treatment fluid (44) from the injector.The exhaust treatment fluid system of claim 21, wherein the laminar flow device (70) comprises a solid core that precludes flow of exhaust treatment fluid (44) therethrough.The exhaust treatment fluid system of claim 21, wherein the cross section of the laminar flow device (70) is cruciform.

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