Retainer shield with wedge lock for diesel exhaust fluid sensor

Abstract

Disclosed is a retainer shield, mating filter, and assembly for diesel exhaust fluid (DEF) systems. The retainer shield, mating filter, and assembly may prevent aerated DEF from entering into an associated measurement chamber including one or more sensors, which can contribute to inaccurate measurements and sensor readings. In an embodiment, the retainer shield may comprise a wedge lock on an interface between the retainer shield and a mating filter. The wedge lock may be positioned on opposite sides of the retainer shield, for example, on the straight or linear sides of the retainer shield. In an embodiment, the retainer shield may comprise a shield that generally corresponds to and covers a central porous membrane of the mating filter. The shield may protrude and provide a space between the shield and the mating filter. A bottom end of shield may include an open portion and a top end of the shield may include a vent hole.

Description

TITLERETAINER SHIELD WITH WEDGE LOCK FOR DIESEL EXHAUST FLUID SENSORCROSS REFERENCE TO RELATED APPLICATIONS

[0001] The application claims priority to U.S. Patent Application No. 63 / 575.100. filed on April 5, 2024, entitled “RETAINER SHIELD WITH WEDGE LOCK FOR DIESEL EXHAUST FLUID SENSOR / ’ which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION

[0002] The disclosure relates to a diesel exhaust fluid (DEF) retainer shield and, more particularly, a diesel exhaust fluid retainer shield comprising a wedge lock that prevents aerated DEF from entering into an associated measurement chamber.BACKGROUND

[0003] Diesel Exhaust Fluid (DEF) tanks and systems have become standard on diesel powered ground vehicles since 2010 in the United States of America. DEF is a reduction agent and an Aqueous Urea Solution (AUS) that can be used in Selective Catalytic Reduction (SCR) diesel emissions systems, which are used to significantly cut nitrogen oxide (NOx) emissions from diesel engines. DEF has unique properties and is necessary’ to the performance of emissions systems on diesel engine equipment using SCR diesel emissions systems. DEF is used on essentially all commercial trucks and other diesel vehicles due to its role in reducing emissions and ensuring compliance of vehicles with environmentalregulations. DEF can also contribute to engine efficiency and reduces fuel consumption. Most modem trucks will not operate properly without DEF and functional DEF systems.

[0004] As such, it is ty pical to provide multiple sensors in the DEF reservoir. These sensors may monitor one or more of the fluid level, fluid temperature, fluid concentration (e.g., urea in water), etc. For example, a DEF fluid level sensor may measure the level of fluid remaining in the DEF tank. When the liquid level is low, the DEF level sensor can send a signal to the vehicle’s electronic control unit, which then triggers the warning light on the gauges or panel of the vehicle. Multiple sensor strategies may be used to discern the reservoir and fluid conditions.

[0005] Most, if not all, sensor technologies (e.g., ultrasonic, thermal dispersion, infrared spectrographic, etc.) are sensitive to air in the DEF. Entrained air (e.g., bubbles) can change the physical characteristics of DEF as well as the behavior of the sensor. For example, entrained air or bubbles embedded in the DEF can disperse the ultrasonic or other signal from the sensor and result in the sensor not receiving the echo reflection. Such entrained air or bubbles embedded in the DEF can cause erratic measurement results or result in no measurement results.

[0006] Regardless of the parameter being measured (e.g., speed of sound, resistance or conductance, specific heat, dynamic viscosity, optical characteristic, etc.), air in the fluid will more than likely negatively impact the measurement or, at minimum, cause the sensor technologies and corresponding measurements to be unreliable and / or undependable. Entrained air can also be the cause of sensor errors, fault codes, and observed measurement fluctuations (e.g., in DEF level, DEF temperature, DEF / urea concentration, etc.) when the vehicle is in use. Entrained air can cause inaccurate measurement readings and / or measurement readings may be unavailable entirely. Entrained air and the inaccurate or unavailable readings can cause disruption to engine performance, dangerous or unpredictablevehicle response, increased emissions, and damage to the vehicle systems requiring repair or increased maintenance. It is possible that No Fault Found (NFF) warrant}' claims may be attributed to the problem of entrained air affecting sensor measurement readings.

[0007] Given this, there is a need in the art for aeration filters and retainers, assemblies, and / or components of measurement chambers that mitigate entrained air or aeration of DEF from entering into the measurement chambers. There is a need for devices and systems that prevent air and fluid including entrained air from entering into an associated measurement chamber and impacting sensor measurements such as level and / or concentration measurements. There is a need for devices and systems that provide one or more (or all) of the following: accurate DEF sensor measurements, reliable sensor measurements, decreased entrained air in DEF, etc.SUMMARY

[0001] The following presents a summary of this disclosure to provide a basic understanding of some aspects. This summary is intended to neither identify key or critical elements nor define any limitations of embodiments or claims. Furthermore, this summary may provide a simplified overview of some aspects that may be described in greater detail in other portions of this disclosure. Any of the described aspects may be isolated or combined with other described aspects without limitation to the same effect as if they had been described separately and in every possible combination explicitly.

[0002] Disclosed is a retainer shield, mating filter, and assembly for diesel exhaust fluid (DEF) systems. The retainer shield, mating filter, and assembly may prevent aerated DEF from entering into an associated measurement chamber including one or more sensors, which can contribute to inaccurate measurements and sensor readings.

[0003] The disclosed aeration filters and retainers, assemblies, and / or components ofmeasurement chambers may mitigate entrained air or aeration of DEF from entering into the measurement chambers. The disclosed devices and systems may prevent air and fluid including entrained air from entering into an associated measurement chamber and impacting sensor measurements such as level and / or concentration measurements. The disclosed devices and systems may provide one or more (or all) of the following: accurate DEF sensor measurements, reliable sensor measurements, decreased entrained air in DEF, and the like.

[0004] In an embodiment, the retainer shield may comprise a wedge lock on an interface between the retainer shield and a mating filter. The wedge lock may be positioned on opposite sides of the retainer shield, for example, on the straight or linear sides of the retainer shield. The wedge lock may prevent bowing of the straight or linear sides of the retainer shield, and provide an improved seal at the interface between the retainer shield and the mating filter. In an embodiment, the retainer shield may comprise a shield that generally corresponds to and covers a central porous membrane of the mating filter. The shield may protrude and provide a space between the shield and the mating filter. A bottom end of shield may include an open portion and a top end of the shield may include a vent hole. The open portion and vent hole may selectively direct DEF through the mating filter and into the associated measurement chamber, while preventing entrained air from entering and allowing air to vent through the vent hole.

[0005] Disclosed is a retainer shield assembly for a Diesel Exhaust Fluid (DEF) system. In an embodiment, the assembly may comprise a retainer shield comprising a front face, a back face, and a border surrounding a central shield. In an embodiment, the assembly may comprise a mating filter comprising a front face, a back face, and a border surrounding a central porous membrane. In an embodiment, the retainer shield may further comprise at least one vent positioned at a top side of the central shield between the central shield and the border of the retainer shield and at least one opening positioned at a bottom side of the centralshield between the central shield and the border of the retainer shield. In an embodiment, the front face of the mating filter may interface with the back face of the retainer shield. In an embodiment, the mating filter and the retainer shield may be selectively attachable.

[0006] In an embodiment, the at least one opening positioned at a bottom side of the central shield between the central shield and the border of the retainer shield comprises a first opening and a second opening separated by a wall. In an embodiment, the first opening and the second opening are different sizes. In an embodiment, the central shield protrudes on or towards the front-face of retainer shield forming a cavity between retainer shield and mating filter. In an embodiment, the central shield of the retainer shield generally corresponds in size and shape to the central porous membrane of mating filter.

[0007] In an embodiment, the border of the retainer shield comprises at least two apertures each configured to receive a fastener. In an embodiment, a first aperture is located at a top wall of the border of the retainer shield and a second aperture is located at a bottom wall of the border of the retainer shield. In an embodiment, the first aperture is located at a comer of the top wall of the border and the second aperture is located at an opposite comer of the bottom wall of the border so the first aperture and second aperture are diagonal from one another. In an embodiment, the at least two apertures are each configured to selectively receive the fastener directly into a measurement chamber. In an embodiment, the fasteners, when selectively coupled through the at least two apertures, do not extend through or contact the mating filter. In an embodiment, the border of retainer shield generally corresponds to the border of mating filter, except that the border of retainer shield extends past the border of mating filter at the at least two apertures on the border of retainer shield.

[0008] In an embodiment, the back face of the mating filter is configured to selectively contact or abut a measurement chamber and wherein the front face of the mating filter is configured to selectively contact or abut the back face of the retainer shield. In anembodiment, the border on the back face of the retainer shield is configured to contact both the border on the front face of the mating filter and a portion of a measurement chamber. In an embodiment, the retainer shield is configured to completely cover the front face of the mating filter when the retainer shield and the mating filter are selectively attached to one another. In an embodiment, the mating filter is hidden or not viewable when selectively sandwiched between a measurement chamber and the retainer shield.

[0009] In an embodiment, the mating filter comprises a generally ovular shape. In an embodiment, the border of the mating filter comprises a top portion and a bottom portion and wherein the top portion and the bottom portion are generally curved or rounded. In an embodiment, the border of the mating filter comprises two opposite side walls, wherein the two opposite side walls are generally straight or linear. In an embodiment, the border of the back face of the mating filter is generally planar or flat.

[0010] In an embodiment, the interface between the front face of the mating filter and the back side of the retainer shield is a w edge-lock interface. In an embodiment, the border of the mating filter comprises two opposite side walls and the border of the retainer shield comprises two opposite side walls. In an embodiment, the wedge-lock interface comprises a protrusion on each of the opposite side w alls of the front-facing border of mating filter and a mating recess on each of the opposite side walls of the back-facing border of retainer shield. In an embodiment, the first mating protrusion and recess may be a different length from the second mating protrusion and recess. In an embodiment, the opposite side walls of each the mating filter and the retainer shield comprise a straight or linear segment and wherein the straight or linear segments of each of the opposite side walls and each of the mating filter and the retainer shield comprise the wedge lock interface. In an embodiment, each of the protrusions include a tapered edge or surface on an inner side of the protrusions and wherein each of the mating recesses include an inclined edge or surface on an inner side of the matingrecesses.

[0011] In an embodiment, the tapered edge or surface of each of the protrusions are configured to contact the inclined edge or surface or each of the mating recesses when the mating filter and retainer shield are selectively attached to one another. In an embodiment, the contact between the tapered edge or surface of each of the protrusions and the inclined edge or surface or each of the mating recesses is configured to generate a wedging force and self-locking effect that prevents any axial or rotational movement between the mating filter and the retainer shield. In an embodiment, the contact between the tapered edge or surface of each of the protrusions and the inclined edge or surface or each of the mating recesses is configured to create a high friction fit between the mating filter and the retainer shield.

[0012] Disclosed is a retainer shield assembly for a Diesel Exhaust Fluid (DEF) system. In an embodiment, the assembly may comprise a retainer shield comprising a front face, a back face, and a border surrounding a central shield, wherein the border comprises two opposite side walls. In an embodiment, the assembly may comprise a mating filter comprising a front face, a back face, and a border surrounding a central porous membrane, wherein the border comprises two opposite side walls. In an embodiment, the back face of the mating filter may be configured to selectively contact or abut a measurement chamber. In an embodiment, the front face of the mating filter may be configured to selectively contact or abut the back face of the retainer shield. In an embodiment, the interface between the front face of the mating filter and the back side of the retainer shield may be a wedge-lock interface.

[0013] In an embodiment, the wedge-lock interface comprises a protrusion on each of the opposite side walls of the front-facing border of mating filter and a mating recess on each of the opposite side walls of the back-facing border of retainer shield. In an embodiment, the first mating protrusion and recess may be a different length from the second mating protrusion and recess. In an embodiment, each of the protrusions include a tapered edge orsurface on an inner side of the protrusions and wherein each of the mating recesses include an inclined edge or surface on an inner side of the mating recesses. In an embodiment, the tapered edge or surface of each of the protrusions are configured to contact the inclined edge or surface or each of the mating recesses when the mating filter and retainer shield are selectively attached to one another.

[0014] In an embodiment, the contact between the tapered edge or surface of each of the protrusions and the inclined edge or surface or each of the mating recesses is configured to generate a wedging force and self-locking effect that prevents any axial or rotational movement between the mating filter and the retainer shield. In an embodiment, the contact between the tapered edge or surface of each of the protrusions and the inclined edge or surface or each of the mating recesses is configured to create a high friction fit between the mating filter and the retainer shield. In an embodiment, the opposite side walls of each the mating filter and the retainer shield comprise a straight or linear segment and wherein the straight or linear segments of each of the opposite side walls and each of the mating filter and the retainer shield comprise the wedge lock interface.

[0015] In an embodiment, the retainer shield further comprises at least one vent positioned at a top side of the central shield between the central shield and the border of the retainer shield and at least one opening positioned at a bottom side of the central shield between the central shield and the border of the retainer shield. In an embodiment, the at least one opening positioned at a bottom side of the central shield between the central shield and the border of the retainer shield comprises a first opening and a second opening separated by a wall. In an embodiment, the first opening and the second opening are different sizes.

[0016] In an embodiment, the central shield protrudes on or towards the front-face of retainer shield forming a cavity between retainer shield and mating filter. In an embodiment, the central shield of the retainer shield generally corresponds in size and shape to the centralporous membrane of mating filter. In an embodiment, the border on the back face of the retainer shield is configured to contact both the border on the front face of the mating filter and a portion of a measurement chamber. In an embodiment, the retainer shield is configured to completely cover the front face of the mating filter when the retainer shield and the mating filter are selectively attached to one another. In an embodiment, the mating filter is hidden or not viewable when selectively sandwiched between a measurement chamber and the retainer shield. In an embodiment, the border of the back face of the mating filter is generally planar or flat.

[0017] In an embodiment, the border of the retainer shield comprises at least two apertures each configured to receive a fastener. In an embodiment, a first aperture is located at a top wall of the border of the retainer shield and a second aperture is located at a bottom wall of the border of the retainer shield. In an embodiment, the first aperture is located at a comer of the top wall of the border and the second aperture is located at an opposite comer of the bottom wall of the border so the first aperture and second aperture are diagonal from one another. In an embodiment, the at least two apertures are each configured to selectively receive the fastener directly into a measurement chamber. In an embodiment, the fasteners, when selectively coupled through the at least two apertures, do not extend through or contact the mating filter. In an embodiment, the border of retainer shield generally corresponds to the border of mating filter, except that the border of retainer shield extends past the border of mating filter at the at least two apertures on the border of retainer shield.

[0018] The following description and the drawings disclose various illustrative aspects. Some improvements and novel aspects may be expressly identified, while others may be apparent from the description and drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present teachings may be better understood by reference to the following detailed description taken in connection with the following illustrations, in which like reference characters refer to like parts throughout, wherein:

[0020] FIG. 1 shows a perspective view of an embodiment of a conventional filter as selectively coupled to a measurement chamber;

[0021] FIG. 2 shows a perspective view of an embodiment of a conventional filter and retainer as selectively coupled to a measurement chamber;

[0022] FIG. 3A shows a front perspective view of an embodiment of a conventional filter;

[0023] FIG. 3B shows a back perspective view of an embodiment of a conventional retainer;

[0024] FIG. 4 shows a cross-sectional view of an embodiment of a conventional filter and retainer as selectively coupled to each other and to a measurement chamber;

[0025] FIG. 5 shows a perspective view of an embodiment of a retainer shield as selectively coupled to a measurement chamber in accordance with aspects disclosed herein;

[0026] FIG. 6 shows a front perspective view of an embodiment of a mating filter in accordance with aspects disclosed herein;

[0027] FIG. 7A shows a front perspective view of an embodiment of a retainer shield in accordance with aspects disclosed herein;

[0028] FIG. 7B shows a back perspective view of an embodiment of a retainer shield in accordance with aspects disclosed herein;

[0029] FIG. 8 shows a cross-sectional view of an embodiment of a mating filter and retainer shield as selectively attached to each other and to a measurement chamber in accordance with aspects disclosed herein;

[0030] FIG. 9 shows a top view of an embodiment of a retainer shield in accordance with aspects disclosed herein; and

[0031] FIG. 10 shows a back view of an embodiment of a retainer in accordance with aspects disclosed herein.

[0032] The invention may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description preceding them. All embodiments that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims.DETAILED DESCRIPTION

[0033] Reference will now be made in detail to exemplary7embodiments of the present teachings, examples of which are illustrated in the accompanying drawings, wherein like numbered aspects refer to a common feature throughout. It is to be understood that other embodiments may be utilized and structural and functional changes may be made without departing from the respective scope of the present teachings. Moreover, features of the various embodiments may be combined or altered without departing from the scope of the present teachings. As such, the following description is presented by way of illustration only and should not limit in any way the various alternatives and modifications that may be made to the illustrated embodiments and still be within the spirit and scope of the present teachings.

[0034] In this disclosure, numerous specific details provide a thorough understanding of the subject disclosure. It should be understood that aspects of this disclosure may be practiced with other embodiments not necessarily including all aspects described herein, etc.

[0035] As used herein, the words '‘example” and “exemplary” means an instance, or illustration. The words “example” or “exemplary” do not indicate a key or preferred aspect or embodiment. The word “or” is intended to be inclusive rather than exclusive, unless context suggests otherwise. As an example, the phrase “A employs B or C,” includes any inclusive permutation (e.g., A employs B; A employs C; or A employs both B and C). As anothermater, the articles “a’' and “an” are generally intended to mean “one or more” unless context suggest otherwise.

[0036] Further, as herein disclosed, the terms “substantially,” “about,” and variations thereof describe features that are equal or approximately equal to a value or characteristic, as desired, reflecting tolerances, conversion factors, rounding off, measurement error, acceptable variation thresholds, and the like. For example, unless context or this disclosure suggests otherwise, the term “substantially” includes values or characteristics that are exact or within 15% of exact (or what is stated), for example within 10% of exact, or within 5% of exact. In another example, unless context or this disclosure suggests otherwise, the term “about” includes values within .5 of a degree to 1 degree of exact (or what is stated).

[0037] Further, unless context suggest otherwise, descriptions of shapes (e.g., circular, rectangular, triangular, etc.) refer to shapes meeting the definition of such shapes and general representation of such shapes. For instance, a triangular shape or generally triangular shape may include a shape that has three sides and three vertices or a shape that generally represents a triangle, such as a shape having three major sides that may or may not have straight edges, triangular like shapes with rounded vertices, etc.

[0038] It is noted that the terms fluid and DEF as referred to herein may generally include fluid and DEF that has entrained air present as well as fluid and DEF that does not have entrained air present unless otherwise stated or context suggests otherwise (e.g., before and after entering through the retainer shield and / or the mating filter, each intended to separate entrained air or prevent fluid having air from entering into the measurement chamber or areas near the sensor). It is also noted that the terms DEF and fluid as referred to herein may generally be used interchangeably and that embodiments described herein may be used in non-diesel applications even if DEF may be described. It is noted that the terms fluidlyconnected and fluidly sealed as used herein may refer to both liquid and air connections and seals unless otherwise stated or context suggests otherwise.

[0039] Turning to FIG. 1, shown is a conventional filter 40. In an embodiment, filter 40 may selectively couple to a measurement chamber 5 that includes one or more sensors. In an embodiment, filter 40 may allow DEF to enter into the measurement chamber 5 to interact with the one or more sensors. For example, the one or more sensors may monitor the fluid level, fluid temperature, fluid concentration (e.g., urea in water), and the like. For example, a DEF fluid level sensor may measure the level of fluid remaining in the DEF tank. In an embodiment, filter 40 may have a generally ovular shape, see FIG. 1. In an embodiment, filter 40 may comprise a border 41 including opposite sides 46. 47 that circumscribe a central porous membrane 49. Both front 42 and back 43 faces of filter 40 and the border 41 thereof may be flat or planar.

[0040] Turning to FIG. 2, shown is a conventional retainer 70. In an embodiment, retainer 70 may selectively couple to filter 40, which may itself selectively couple to the measurement chamber 5 as described herein. In an embodiment, retainer 70 may have a generally ovular shape, see FIG. 2. In an embodiment, retainer 70 may comprise a border 71 including opposite sides 76, 77 that circumscribe a central, open window 79. Both front 72 and back 73 faces of retainer 70 and the border 71 thereof may be flat or planar. In an embodiment, retainer 70 may have a shape that generally corresponds to a shape of the filter 40. Generally, the border 71 of retainer 70 may generally correspond to the border 41 of filter 40. In an embodiment, an interface 85 between the back-facing 73 border 71 (e.g., sides 76, 77) of retainer 70 and the front-facing 42 border 41 (e.g., sides 46, 47) of filter 40 may comprise contact between the flat or planar surfaces of each the retainer 70 and filter 40, see FIGs. 3-4, for example. Generally, the central window 79 of retainer 70 may generally correspond to the central porous membrane 49 of filter 40. In an embodiment, central window 79 of retainer 70may allow DEF to pass through into the exposed central porous membrane 49 of filter 40.

[0041] Due to the structure of the conventional filter 40 and retainer 70, including a flat interface 85 between the filter 40 and retainer 70 when selectively coupled and an exposed central porous membrane 49 of filter 40 through central window 79 of retainer 70, the central window 79 of retainer 70 which generally corresponds in size and shape to the size and shape of the central porous membrane 49 of filter 40, the system is susceptible to entrained air entering the measurement chamber 5 and disrupting the accuracy of the measurements. For example, the opposite sides 46. 47 of filter 40 and the opposite sides 76, 77 of retainer 70 being generally linear or straight and having a flat interface 85 therebetween, may be unable to seal and can result in bowing or misaligning of the borders, that can allow air to enter measurement chamber 5. For example, during a fill event, DEF shooting directly onto the exposed central porous membrane 49 of filter 40 through central window 79 of retainer 70 can push air bubbles into measurement chamber 5. Air bubbles entering into measurement chamber 5 can lead to incorrect concentration and level readings, in an example. It has been found that the flat interface 85 between retainer 70 and filter 40 may contribute to unwanted air entering measurement chamber 5. It has been found that the exposed central porous membrane 49 of filter 40 through central window 79 of retainer 70 may contribute to unwanted air entering measurement chamber 5.

[0042] Disclosed is an improved retainer shield, mating filter, and assembly for diesel exhaust fluid (DEF) systems. The retainer shield, mating filter, and assembly may prevent aerated DEF from entering into an associated measurement chamber including one or more sensors, which can otherwise contribute to inaccurate measurements and sensor readings. The structures and designs may provide one or more (or all) of the following: accurate DEF sensor measurements, reliable sensor measurements, decreased entrained air in DEF, and the like. The structures and designs may provide one or more (or all) of the following: animproved seal between the interface of the retainer shield and mating filter, prevention of bowing or misaligning of the borders of the components, protection or covering the central porous membrane of filter with a shield so that the central porous membrane of filter is not wholly exposed to the surrounding area, a pathway for DEF to enter into a space between the shield and the central porous membrane of filter, an inlet that selectively encourages entrance of DEF without entrained air and prevents entrance of DEF including entrained air, a vent that allows venting of any air that may enter the inlet and pathway, and the like, resulting in less entrained air from entering into the associated measurement chamber and negatively impacting sensor readings.

[0043] Turning to FIG. 5, shown is a retainer shield 105. Retainer shield 105 may be selectively coupled to a mating filter 155 and mating filter 155 may be selectively coupled to an associated measurement chamber 5, see FIGs. 5 and 8, for example. It is noted that when the retainer shield 105 and mating filter 155 are selectively coupled to the associated measurement chamber 5, retainer shield 105 may cover the mating filter 155 so that mating filter 155 is not visible, see FIG. 5. The retainer shield assembly, e.g.. comprising retainer shield 105 and mating filter 155, may be selectively coupled to the associated measurement chamber 5 and may selectively allow DEF into the measurement chamber 5 through the retainer shield assembly. In an embodiment, the measurement chamber 5 may include one or more sensors. In an embodiment, retainer shield assembly may selectively allow DEF into the measurement chamber 5 to interact with the one or more sensors. For example, the one or more sensors may monitor the fluid level, fluid temperature, fluid concentration (e.g., urea in water), and the like. For example, a DEF fluid level sensor may measure the level of fluid remaining in the DEF tank. The retainer shield assembly may result in less entrained air entering the measurement chamber 5 and may be less susceptible to inaccurate sensor readings. It is noted that the retainer shield 105 and mating filter 155 may be together referredto as a retainer shield assembly.

[0044] Turning to FIG. 6, shown is mating filter 155. Mating filter 155 may be selectively coupled to retainer shield 105 on one side or face (e g., front-facing side 158 of mating filter 155) and may be selectively coupled to the associated measurement chamber 5 on the other side or face (e.g., back-facing side 159 of mating filter 155). In an embodiment, mating filter 155 may have a generally ovular shape, see FIG. 6. It is noted that mating filter 155 may have any other shape as may be suitable or desired for a particular purpose or intended application. For example, mating filter 155 may resemble a parallelogram, rhombus, diamond, rectangle, square, oval, circle, irregular shape, etc. In an embodiment, mating filter 155 may comprise a border 157 including two opposite side walls 162. 163 (and top and bottom portions) that circumscribe or surround a central porous membrane 195. In an embodiment, the two opposite side walls 162. 163 may be generally straight or linear. As described herein, the corresponding wedge lock interface 180 on mating filter 155 may be located on each of the opposite side walls 162. 163, particularly on the straight or linear segments of the opposite side walls 162, 163. In an embodiment, top and bottom portions of the mating filter 155 may be generally curved or rounded.

[0045] In an embodiment, mating filter 155 may comprise a front face 158 and a back face 159. It is noted that the front face and the back face may also be referred to as first and second faces, respectively. In an embodiment, the back face 159 of mating filter 155 may contact or abut the measurement chamber 5 and the front face 158 of mating filter 155 may contact or abut a back face of retainer shield 105. Mating filter 155 may be fully or near fully covered by retainer shield 105 (except for bottom openings / slits and top vent of retainer shield 105), and mating filter 155 may be generally hidden or not viewable when sandwiched between measurement chamber 5 and retainer shield 105. In an embodiment, the back-facing border 159 may be generally planar or flat. In an embodiment, the front-facing border 158may comprise a wedge lock which interfaces with a corresponding wedge lock on the back- facing border of retainer shield 105.

[0046] In an embodiment, retainer shield 105 may comprise a border 107 having two opposite side walls 1 12, 1 13, a top wall 130, and a bottom wall 135, see FIGs. 7A-B. It is noted that the top wall and the bottom wall may also be referred to as first and second walls, respectively. In an embodiment, the two opposite side walls 112, 113 may be generally straight or linear. As described herein, the corresponding wedge lock interface 180 on retainer shield 105 may be located on each of the opposite side walls 112, 113. particularly on the straight or linear segments of the opposite side walls 112. 113. In an embodiment, the top wall 130 and the bottom wall 135 may be angled and the comers thereof may be rounded. For example, opposite angled comers of the top wall 130 and bottom wall 135 may each include an aperture 118, 119 configured to receive a fastener, see FIGs. 5 and 7. The apertures 118, 119, in an embodiment, may extend through the retainer shield 105 and the fasteners may extend through the retainer shield 105 and directly into the measurement chamber 5 (e.g., a housing or exterior thereof). In an embodiment, the fasteners may not extend through or contact the mating filter 155. Retainer shield 105 may have a generally rectangular, ovular, or rounded shape, see FIGs. 5-6, for example. It is noted that retainer shield 105 may have any other shape as may be suitable or desired for a particular purpose or intended application. For example, retainer shield 105 may resemble a parallelogram, rhombus, diamond, rectangle, square, oval, circle, irregular shape, etc.

[0047] In an embodiment, retainer shield 105 may have a shape that generally corresponds to a shape of the mating filter 155. In an embodiment, the border 107 of retainer shield 105 may generally correspond to the border 157 of mating filter 155. In an embodiment, the border 107 of retainer shield 105 may generally correspond to the border 157 of mating filter 155, except that the border 107 of retainer shield 105 may extend past the border 157 of matingfilter 155 at the opposite angled comers of the top wall 130 and bottom wall 135 of the retainer shield 105 including apertures 118, 119 to accommodate the fasteners. In an embodiment, the border 107 of retainer shield 105 may be slightly larger or wider than the border 157 of mating filter 155 about a circumference or perimeter of retainer shield 105 compared to mating filter 155. In an embodiment, the borders 107, 157 of retainer shield 105 and mating filter 155 may overlap at the wedge lock interface 180, see FIG. 8. In an embodiment, the border 107 of retainer shield 105 may contact or abut both the border of mating filter 155 and a portion of the measurement chamber 5 (e.g., a housing or exterior thereol), see FIG. 8. For example, back-facing border 109 of retainer shield 105 may contact or abut both the front-facing border 158 of mating filter 155 and a portion of the measurement chamber 5 (e.g., a housing or exterior thereof), see FIG. 8.

[0048] In an embodiment, the retainer shield 105 may have a front face 108 and a back face 109, see FIGs. 7A-B. It is noted that the front face and the back face may also be referred to as first and second faces, respectively. When selectively coupled to mating filter 155, the back face 109 of retainer shield 105 may contact or abut a front face of mating filter 155 (and back face 109 of retainer shield 105 may contact or abut measurement chamber 5) and the front face 108 of retainer shield 105 may be outward-facing and otherwise remain exposed or visible when retainer shield 105 is selectively coupled to mating filter 155. In an embodiment, the front-facing border 108 may be generally planar or flat. In an embodiment, the back-facing border may comprise a wedge lock which interfaces with a corresponding wedge lock on the front-facing border of mating filter 155. As described herein, the wedge lock interface 180 of retainer shield 105 and mating filter 155 may provide improved seal at the interface between corresponding surfaces and may prevent of bowing or misaligning of the borders of the components compared to the conventional retainer and filter comprising a flat interface, see FIG. 4 showing the flat interface 85 compared to FIG. 8 showing the w edgelock interface 180.

[0049] As described herein, wedge lock interface 180 facilitate a connection between retainer shield 105 and mating filter 155. In an embodiment, wedge lock interface 180 may be located on the back-facing border 109 of retainer shield 1 5 and on the front-facing border 158 of mating filter 155. In an embodiment, wedge lock interface 180 may be located on the straight or linear segments of the opposite side walls 112, 1 13 of retainer shield 105 and the opposite side walls 162, 163 of mating filter 155. In an embodiment, the wedge lock interface 180 may include two mating or fitting components that include tapered surfaces or inclined planes. The tapered surfaces or inclined planes may contact or abut one another when brought together. When an external force is applied, the tapered surfaces or inclined planes can push against one another and generate a wedging force and self-locking effect that prevents any axial or rotational movement between components. In an embodiment, the wedging force may create high frictional forces between the contact surfaces, preventing the surfaces from becoming separate or loose from one another. In an embodiment, the wedging force can also help to distribute the applied load more evenly along the mating surfaces, reducing the risk of localized stress concentrations.

[0050] Generally, wedge lock interface 180 may include a protrusion 188 and a recess 184 that mate and interlock with one another. As shown in the FIGs., the wedge lock interface 180 may include a pair of protrusions 188, 189 and a pair of recesses 184, 185 on the side walls of the border of the mating filter 155 and retainer shield 105, respectively, configured to interact with one another to form a lock between the mating filter 155 and retainer shield 105 components. It is noted that the protrusions 188, 189 on the mating filter 155 may be generally the same and descriptions herein for one may apply to the other, except the length or width between the protrusions 188, 189 may be different. It is noted that the recesses 184, 185 on the retainer shield 105 may be generally the same and descriptions herein for one mayapply to the other, except the length or width between the recesses 184, 185 may be different.

[0051] For example, protrusion 188 may be sized and shaped to interact with and lock into recess 184. For example, protrusion 189 may be sized and shaped to interact with and lock into recess 185. In an embodiment, the protrusion recess interlock 188 / 184 may have a different size (e.g., length and / or width, etc.) than the protrusion recess interlock 189 / 185. In an embodiment, the protrusion recess interlock 188 / 184 may have a different length than the protrusion recess interlock 189 / 185. The different sizes of the mating protrusions and / or recesses may be so a user will always be able to position the mating filter 155 and / or the retainer shield 105 in the correct position, e.g.. protrusion 188 can only fit in the corresponding recess 184 on that side of the assembly. In other words, the different sizes will only permit the mating filter 155 and / or the retainer shield 105 to be installed in one-way (e.g., not upside down, for example).

[0052] As described, each the protrusion 188 (and protrusion 189) and recess 184 (and recess 185) may include corresponding tapered and inclined surfaces that are configured to contact or abut one another when retainer shield 105 and mating filter 155 are brought together. As described, it is noted that the descriptions herein for protrusion 188 may also apply to protrusion 189 even if not directly stated unless context or this description suggests otherwise (e.g., pertaining to different lengths, for example). As described, it is noted that the descriptions herein for recess 184 may also apply to recess 185 even if not directly stated unless context or this description suggests otherwise (e.g., pertaining to different lengths, for example). The wedge lock interface 180 may include one or more protrusions 188 and one or more corresponding recesses 184. In an embodiment, the wedge lock interface 180 may include two protrusions 188, 189 and two corresponding recesses 184, 185. For example, as shown in FIGs. 6 and 8, the front-facing border 158 of mating filter 155 may include a protrusion 188, 189 on each of the opposite side walls 162, 163.

[0053] It is noted that the protrusions may be located instead on retainer shield 105 or on a different portion of mating filter 155. It is also noted that the mating filter 155 may include a combination of protrusions and recesses, e.g., a protrusion on one side wall 162 and a recess on the other side wall 163, or each side wall 162, 163 having both recesses and protrusions. In any case, the protrusions 188 and / or recesses 184 will correspond to the opposite surface feature on the mating retainer shield 105. In an embodiment, each protrusion 188 may be generally linear and may follow the contour or shape of each of the opposite side walls 162, 163 of mating filter 155. In an embodiment, each protrusion 188 may extend along a length of each of the opposite side walls 162, 163 of mating filter 155, e.g., a central length, a majority of the sidewall length, nearly all of the sidewall length, or the like. In an embodiment, the protrusions 188 may be identical or mirrored. In an embodiment, the protrusions 188 may include an angled edge or wedge-shape. In an embodiment, the protrusions 188 may include a tapered edge or surface. In an embodiment, the tapered edge or surface may be located on an inner side of the protrusions 188. In an embodiment, an outer side of the protrusions 188 may be straight, squared, or curved. The protrusions 188 may generally mimic the negative space created by the corresponding recesses 184 to provide a mating fit between the interface of the components.

[0054] Generally, the shape of the protrusions 188 (and protrusion 189) may correspond to the shape of the corresponding recesses 184 (and recess 185). As described, for each tapered surface, there may be a corresponding and related inclined surface, and vice versa. For example, as shown in FIGs. 7 and 8, the back-facing border 109 of retainer shield 105 may include a recess 184, 185 on each of the opposite side walls 112, 113.

[0055] It is noted that the recesses may be located instead on mating filter 105 or on a different portion of retainer shield 105. It is also noted that the retainer shield 105 may include a combination of protrusions and recesses, e.g., a protrusion on one side wall 112 anda recess on the other side wall 113, or each side wall 112, 113 having both recesses and protrusions. In any case, the protrusions 188 and / or recesses 184 will correspond to the opposite surface feature on the mating filter 155. In an embodiment, each recess 184 may be generally linear and may follow the contour or shape of each of the opposite side walls 112, 113 of retainer shield 105. In an embodiment, each recess 184 may extend along a length of each of the opposite side walls 112, 113 of retainer shield 105, e.g., a central length, a majority of the sidewall length, nearly all of the sidewall length, or the like. In an embodiment, the recesses 184 may be identical or mirrored. In an embodiment, the recesses 184 may include an angled edge or wedge-shape. In an embodiment, the recesses 184 may include an inclined edge or surface. In an embodiment, the inclined edge or surface may be located on an inner side of the recesses 184. In an embodiment, an outer side of the recesses 184 may be straight, squared, or curved. The recesses 184 may generally mimic the positive space created by the corresponding protrusions 188 to provide a mating fit between the interface of the components.

[0056] Although a wedge lock 180 interface is herein described, it is noted that the interface between retainer shield 105 and mating filter 155 may include any mating mechanism and structure as may be suitable or desired for a particular purpose or intended application, including, for example, threading, friction fit, pressure fit, snap-fit, bayonet attachments, cam locks, latches, magnets, tabs, pins, interlocks, and the like. The described wedge lock 180 or other mating interface may provide an improved connection between components, e.g., on the straight or linear sides of the components that may otherwise be susceptible to bowing or misaligning of the borders due to, for example, the conventional flat interface between components. In conventional systems, such as those shown in FIGs. 1-4, for example, such bowing or misaligning of the borders as well as the conventional flat interface between components can inadvertently allow DEF fluid with entrained air or air bubbles generally toenter the measurement chamber 5 and negatively impact sensor readings therein. The described wedge lock 180 or other mating interface may prevent entrained air and air bubbles generally from entering the measurement chamber 5 and may therefore result in more accurate and reliable sensor readings therein.

[0057] As described herein, retainer shield 105 may generally cover and protect mating filter 155 so that mating filter 155 is not exposed to the surrounding environment (except through the small openings in retainer shield 105) and mating filter 155 may not be visible when the retainer shield 105 is selectively coupled onto mating filter 155 and both are selectively coupled onto measurement chamber 5. In an embodiment, retainer shield 105 may generally cover and protect the central porous membrane 195 of mating filter 155 so that the central porous membrane 195 of mating filter 155 is not exposed to the surrounding environment (except through the small openings in retainer shield 105) and the central porous membrane 195 of mating filter 155 may not be visible when the retainer shield 105 is selectively coupled onto mating filter 155 and both are selectively coupled onto measurement chamber 5.

[0058] In an embodiment, retainer shield 105 may comprise a shield or cover 140. In an embodiment, the shield 140 may be a central shield 140 that connects to and lies within the border 107 of retainer shield 105. In an embodiment, border 107 may generally circumscribe or surround shield 140 of retainer shield 140. In an embodiment, shield 140 may generally correspond to and cover the central porous membrane 195 of mating filter 155, compare FIGs. 6 and 7A-B, for example. In an embodiment, shield 140 may protrude on or towards the front-facing side 108 of retainer shield 105. In an embodiment, shield 140 may be recessed on or away from the back-facing side 109 of retainer shield 105. In an embodiment, the protrusion or recess of shield 140 may provide a space or cavity 141 on the back-facing side 109 of retainer shield 105. For example, when the back-facing side 109 of retainer shield 105 is selectively coupled to front-facing side 158 of mating filter 155, the protrusion orrecess of shield 140 may provide a space or cavity 141 therebetween retainer shield 105 and mating filter 155, see FIG. 8, for example, showing space 141 between the shield 140 of retainer shield 105 and the central porous membrane 195 of mating filter 155.

[0059] In an embodiment, space 141 between retainer shield 105 and mating filter 155 may provide a fluid pathway into and through the retainer shield 105 and mating filter 155. For example the bottom end 135 of retainer shield 105, e.g., between border 107 and shield 140, may include one or more slits or openings. The one or more openings at the bottom end 135 of retainer shield 105. e.g., between border 107 and shield 140, may also be referred to as inlets. The one or more openings at the bottom end 135 of retainer shield 105, e.g.. between border 107 and shield 140. may allow fluid, e.g. DEF to enter therethrough the retainer shield 105 and into space 141.

[0060] As show n in FIGs. 6A-B, for example, the bottom end 135 of retainer shield 105, e.g., between border 107 and shield 140, may include a first opening 136 and a second opening 138 separated by a wall 137. In an embodiment, one of the openings 136 may be smaller than the other opening. In an embodiment, the wall 137 may be positioned approximately between * / 4 to % of the bottom end 135 between border 107 and shield 140. In an embodiment, second opening 138 may be approximately 3 times larger that first opening 136, where second opening 138 comprises about % of the overall opening and first opening 136 comprises about 1 of the overall opening. In an embodiment, the small size of the openings 136, 138, the wall 137, and the location of the foregoing at the bottom end 135 of retainer shield 105 may prevent entrained air and air bubbles from entering therein. In an embodiment, the one or more openings and / or walls may be sized and positioned so as to optimize fluid exchange.

[0061] In an embodiment, space 141 between retainer shield 105 and mating filter 155 may provide a fluid pathway out of and through the retainer shield 105 (without going through mating filter 155). For example the top end 130 of retainer shield 105, e.g., between border107 and shield 140, may include one or more vents 132. The one or more vents at the top end 130 of retainer shield 105, e.g., between border 107 and shield 140, may also be referred to as outlets. The one or more vents at the top end 130 of retainer shield 105, e.g., between border 107 and shield 140, may allow air, e.g. DEF including entrained air to exit therethrough the retainer shield 105 from space 141. In an embodiment, the one or more vents may be sized and positioned so as to optimize fluid exchange. As shown in FIGs. 6A-B, for example, the top end 130 of retainer shield 105, e.g., between border 107 and shield 140, may include a one vent 132. In an embodiment, the small size of the vent 132, and the location of the foregoing at the top end 130 of retainer shield 105 may allow entrained air and air bubbles to exit therethrough.

[0062] Although two openings and one wall are described herein, it is noted that any number of openings and walls may be adapted to bottom end 135 or any other location on retainer shield 105 generally as may be suitable or desired for a particular purpose or intended application. Although a 1:3 ratio of the two openings is herein described, it is noted that any ratio of size of the openings may be adapted to bottom end 135 or retainer shield 105 generally as may be suitable or desired for a particular purpose or intended application. Although one vent is described herein, it is noted that any number of vents may be adapted to top end 130 or any other location on retainer shield 105 generally as may be suitable or desired for a particular purpose or intended application.

[0063] In conventional systems, such as those shown in FIGs. 1-4, for example, the exposed central porous membrane of the filter through the open central window- of the conventional shield can inadvertently contribute to unwanted air entering measurement chamber 5. During fill events, for example, or higher intensity movement of fluid in the system, DEF shooting directly onto the exposed central porous membrane of the conventional filter through the conventional retainer can push air bubbles into measurement chamber 5. The describedretainer shield 105 and shield 140 thereof can provide protection to the central porous membrane 195 of mating filter 155 and direct flow of DEF through a more controlled and less intense pathway into and through the central porous membrane 195 of mating filter 155. The described retainer shield 105 and shield 140 thereof may prevent entrained air and air bubbles generally from entering the measurement chamber 5 and may therefore result in more accurate and reliable sensor readings therein. The bottom opening(s) and top vent may prevent aerated fluid from directly entering measurement chamber 5. The retainer shield 105 and mating filter 155 may provide a pathway for DEF to enter into the space between the retainer shield 105 and the central porous membrane 195 of mating filter 155 where the inlet or bottom opening(s) may selectively encourage entrance of DEF without entrained air and prevent entrance of DEF including entrained air and where outlet or top vent may allows venting of any air that may enter the inlet and pathway. The bottom opening(s) and vent may selectively direct DEF into the retainer shield 105 and through the mating filter 155 into the associated measurement chamber 5, while preventing entrained air from entering therethrough and / or allowing air to vent.

[0064] As shown in FIG. 10, retainer shield 205 may be provided including a wedge lock interface by not including shield having inlets / outlets. Retainer shield 205 may be the same as retainer shield 105 in all other respects except for shield having inlets / outlets as described. While performance results of retainer shield 205 show improved results from baseline (e.g., conventional systems), the results show evidence of bubble intrusion into the measurement chamber on several of the test runs when filling the tank from empty, suggesting that the exposed central porous membrane can contribute to bubble intrusion. Performance results for retainer shield 105, including a wedge lock interface and including shield having inlets / outlets show consistent and improved performance in preventing bubble intrusion into the measurement chamber. As a result, disclosed and described are improved retainer shields105, 205 including either or both a wedge lock interface and / or shield having inlets / outlets to prevent entrained air from entering into the associated measurement chambers and negatively impacting measurement results and sensor readings.

[0065] Although the embodiments of the present teachings have been illustrated in the accompanying drawings and described in the foregoing detailed description, it is to be understood that the present teachings are not to be limited to just the embodiments disclosed, but that the present teachings described herein are capable of numerous rearrangements, modifications and substitutions without departing from the scope of the claims hereafter. The claims as follows are intended to include all modifications and alterations insofar as they come within the scope of the claims or the equivalent thereof.

Claims

CLAIMSWhat is claimed is:

1. A retainer shield assembly for a Diesel Exhaust Fluid (DEF) system, comprising: a retainer shield comprising a front face, a back face, and a border surrounding a central shield; a mating filter comprising a front face, a back face, and a border surrounding a central porous membrane; wherein the retainer shield further comprises at least one vent positioned at a top side of the central shield between the central shield and the border of the retainer shield and at least one opening positioned at a bottom side of the central shield between the central shield and the border of the retainer shield; wherein the front face of the mating filter interfaces with the back face of the retainer shield and wherein the mating filter and the retainer shield are selectively attachable.

2. The retainer shield assembly of claim 1, wherein the at least one opening positioned at a bottom side of the central shield between the central shield and the border of the retainer shield comprises a first opening and a second opening separated by a wall.

3. The retainer shield assembly of claim 2, wherein the first opening and the second opening are different sizes.

4. The retainer shield assembly of claim 1, wherein the central shield protrudes on or towards the front-face of retainer shield forming a cavity between retainer shield and mating filter.

5. The retainer shield assembly of claim 1, wherein the central shield of the retainer shield generally corresponds in size and shape to the central porous membrane of mating filter.

6. The retainer shield assembly of claim 1, wherein the border of the retainer shield comprises at least two apertures each configured to receive a fastener.

7. The retainer shield assembly of claim 6, wherein a first aperture is located at a top wall of the border of the retainer shield and a second aperture is located at a bottom wall of the border of the retainer shield.

8. The retainer shield assembly of claim 7, wherein the first aperture is located at a comer of the top wall of the border and the second aperture is located at an opposite comer of the bottom wall of the border so the first aperture and second aperture are diagonal from one another.

9. The retainer shield assembly of claim 6, wherein the at least two apertures are each configured to selectively receive the fastener directly into a measurement chamber.

10. The retainer shield assembly of claim 6, wherein the fasteners, when selectively coupled through the at least two apertures, do not extend through or contact the mating filter.

11. The retainer shield assembly of claim 6, wherein the border of retainer shield generally corresponds to the border of mating filter, except that the border of retainer shieldextends past the border of mating filter at the at least two apertures on the border of retainer shield.

12. The retainer shield assembly of claim 1, wherein the back face of the mating filter is configured to selectively contact or abut a measurement chamber and wherein the front face of the mating filter is configured to selectively contact or abut the back face of the retainer shield.

13. The retainer shield assembly of claim 1, wherein the border on the back face of the retainer shield is configured to contact both the border on the front face of the mating filter and a portion of a measurement chamber.

14. The retainer shield assembly of claim 1, wherein the retainer shield is configured to completely cover the front face of the mating filter when the retainer shield and the mating filter are selectively attached to one another.

15. The retainer shield assembly of claim 1, wherein the mating filter is hidden or not viewable when selectively sandwiched between a measurement chamber and the retainer shield.

16. The retainer shield assembly of claim 1, wherein the mating filter comprises a generally ovular shape.

17. The retainer shield assembly of claim 1, wherein the border of the mating filter comprises a top portion and a bottom portion and wherein the top portion and the bottom portion are generally curved or rounded.

18. The retainer shield assembly of claim 1, wherein the border of the mating filter comprises two opposite side walls, wherein the two opposite side walls are generally straight or linear.

19. The retainer shield assembly of claim 1, wherein the border of the back face of the mating filter is generally planar or flat.

20. The retainer shield assembly of claim 1, wherein the interface between the front face of the mating filter and the back side of the retainer shield is a wedge-lock interface.

21. The retainer shield assembly of claim 20, wherein the border of the mating filter comprises two opposite side walls and the border of the retainer shield comprises two opposite side walls; and wherein the wedge-lock interface comprises a protrusion on each of the opposite side walls of the front-facing border of mating filter and a mating recess on each of the opposite side walls of the back-facing border of retainer shield.

22. The retainer shield assembly of claim 21, wherein each of the protrusions include a tapered edge or surface on an inner side of the protrusions and wherein each of the mating recesses include an inclined edge or surface on an inner side of the mating recesses.

23. The retainer shield assembly of claim 22, wherein the tapered edge or surface of each of the protrusions are configured to contact the inclined edge or surface or each of the mating recesses when the mating filter and retainer shield are selectively attached to one another.

24. The retainer shield assembly of claim 23, wherein the contact between the tapered edge or surface of each of the protrusions and the inclined edge or surface or each of the mating recesses is configured to generate a wedging force and self-locking effect that prevents any axial or rotational movement between the mating filter and the retainer shield.

25. The retainer shield assembly of claim 23, wherein the contact between the tapered edge or surface of each of the protrusions and the inclined edge or surface or each of the mating recesses is configured to create a high friction fit between the mating filter and the retainer shield.

26. The retainer shield assembly of claim 21, wherein the opposite side walls of each the mating filter and the retainer shield comprise a straight or linear segment and wherein the straight or linear segments of each of the opposite side walls and each of the mating filter and the retainer shield comprise the wedge lock interface.

27. A retainer shield assembly for a Diesel Exhaust Fluid (DEF) system, comprising: a retainer shield comprising a front face, a back face, and a border surrounding a central shield, wherein the border comprises two opposite side walls; a mating filter comprising a front face, a back face, and a border surrounding a central porous membrane, wherein the border comprises two opposite side walls;wherein the back face of the mating filter is configured to selectively contact or abut a measurement chamber and wherein the front face of the mating filter is configured to selectively contact or abut the back face of the retainer shield; wherein the interface between the front face of the mating filter and the back side of the retainer shield is a wedge-lock interface.

28. The retainer shield assembly of claim 27, wherein the wedge-lock interface comprises a protrusion on each of the opposite side walls of the front-facing border of mating filter and a mating recess on each of the opposite side walls of the back -facing border of retainer shield.

29. The retainer shield assembly of claim 28, wherein each of the protrusions include a tapered edge or surface on an inner side of the protrusions and wherein each of the mating recesses include an inclined edge or surface on an inner side of the mating recesses.

30. The retainer shield assembly of claim 29, wherein the tapered edge or surface of each of the protrusions are configured to contact the inclined edge or surface or each of the mating recesses when the mating filter and retainer shield are selectively attached to one another.

31. The retainer shield assembly of claim 30, wherein the contact between the tapered edge or surface of each of the protrusions and the inclined edge or surface or each of the mating recesses is configured to generate a wedging force and self-locking effect that prevents any axial or rotational movement between the mating filter and the retainer shield.

32. The retainer shield assembly of claim 30, wherein the contact between the tapered edge or surface of each of the protrusions and the inclined edge or surface or each of themating recesses is configured to create a high friction fit between the mating filter and the retainer shield.

33. The retainer shield assembly of claim 28, wherein the opposite side walls of each the mating filter and the retainer shield comprise a straight or linear segment and wherein the straight or linear segments of each of the opposite side walls and each of the mating filter and the retainer shield comprise the wedge lock interface.

34. The retainer shield assembly of claim 27, wherein the retainer shield further comprises at least one vent positioned at atop side of the central shield between the central shield and the border of the retainer shield and at least one opening positioned at a bottom side of the central shield between the central shield and the border of the retainer shield.

35. The retainer shield assembly of claim 34, wherein the at least one opening positioned at a bottom side of the central shield between the central shield and the border of the retainer shield comprises a first opening and a second opening separated by a wall.

36. The retainer shield assembly of claim 35, wherein the first opening and the second opening are different sizes.

37. The retainer shield assembly of claim 27, wherein the central shield protrudes on or towards the front-face of retainer shield forming a cavity between retainer shield and mating filter.

38. The retainer shield assembly of claim 27, wherein the central shield of the retainer shield generally corresponds in size and shape to the central porous membrane of mating filter.

39. The retainer shield assembly of claim 27, wherein the border on the back face of the retainer shield is configured to contact both the border on the front face of the mating filter and a portion of a measurement chamber.

40. The retainer shield assembly of claim 27, wherein the retainer shield is configured to completely cover the front face of the mating filter when the retainer shield and the mating filter are selectively attached to one another.

41. The retainer shield assembly of claim 27, wherein the mating filter is hidden or not viewable when selectively sandwiched between a measurement chamber and the retainer shield.

42. The retainer shield assembly of claim 27, wherein the border of the back face of the mating filter is generally planar or flat.

43. The retainer shield assembly of claim 27, wherein the border of the retainer shield comprises at least two apertures each configured to receive a fastener.

44. The retainer shield assembly of claim 43, wherein a first aperture is located at a top wall of the border of the retainer shield and a second aperture is located at a bottom wall of the border of the retainer shield.

45. The retainer shield assembly of claim 44, wherein the first aperture is located at a comer of the top wall of the border and the second aperture is located at an opposite comer of the bottom wall of the border so the first aperture and second aperture are diagonal from one another.

46. The retainer shield assembly of claim 43, wherein the at least two apertures are each configured to selectively receive the fastener directly into a measurement chamber.

47. The retainer shield assembly of claim 43, wherein the fasteners, when selectively coupled through the at least two apertures, do not extend through or contact the mating filter.

48. The retainer shield assembly of claim 43, wherein the border of retainer shield generally corresponds to the border of mating filter, except that the border of retainer shield extends past the border of mating filter at the at least two apertures on the border of retainer shield.

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