Injection valve for a reducing agent dispensing unit with fluid volume reduction arrangement

Abstract

Reducing agent delivery unit (10) comprising: a fluid injection valve (12) having a fluid inlet (30) arranged at a first end of the fluid injection valve (12) for receiving a reducing agent, and having a fluid outlet (32) arranged at a second end of the fluid injection valve (12) for discharging the reducing agent, wherein the fluid injection valve (12) defines a fluid path for the reducing agent from the fluid inlet (30) to the fluid outlet (32), wherein the fluid injection valve (12) comprises: a tubular element (42) having one end disposed at the fluid inlet (30) of the fluid injection valve (12), the tubular element (42) being configured to conduct reducing agent along the fluid path; a filter (204) disposed in the tubular member (42) proximal to the fluid inlet (30) of the fluid injection valve (12); a volume reducing element (208) arranged in the tubular element (42) downstream of the filter (204) with respect to a direction of the reducing agent flow along the fluid path from the fluid inlet (30) to the fluid outlet (32) of the fluid injection valve (12), wherein the volume reducing element (208) contacts an inner surface of the tubular element (42) and comprises a bore (208A) defined by the volume reducing element (208), wherein the bore (208A) defines at least a portion of the fluid path through the fluid injection valve (12), wherein the diameter of the bore is between 12% and 20% of the outer diameter of the volume reducing element (208) and the volume reducing element (208) occupies a volume in the tubular element (42) such that the volume reducing element (208) reduces a volume of the fluid path occupied by the reducing agent in the fluid injection valve (12); and a cap member (206) in which the filter (204) is arranged, the cap member (206) being engaged with and secured to the volume reducing member (208) such that the filter (204), the volume reducing member (208) and the cap member (206) form a single member.

Description

Scope of the invention

[0001] The present invention relates generally to a reductant delivery unit (RDU) fluid injection valve, and more particularly to a robust RDU fluid injection valve for purge-free applications. background

[0002] Emissions regulations in Europe and North America are driving the adoption of new exhaust aftertreatment systems, particularly for lean-burn engine technologies such as compression-ignition (diesel) and spark-ignition (usually direct-injected) engines operating under lean and ultra-lean conditions. Lean-burn engines exhibit high nitrogen oxide (NOx) emissions, which are difficult to treat in the oxygen-rich exhaust environments typical of lean-burn combustion. Exhaust aftertreatment technologies that address NOx under these conditions are currently being developed.

[0003] One of these technologies involves a catalyst that facilitates the reaction of ammonia (NH3) with nitrogen oxides (NOx) to form nitrogen (N2) and water (H2O). This technology is called selective catalytic reduction (SCR). Ammonia is difficult to handle in its pure form in the automotive environment, so it is common for these systems to use a diesel exhaust fluid (DEF) and / or a liquid aqueous urea solution, typically at a urea concentration of 32% (CO(NH2)2). The solution is referred to as AUS-32 and is also known by the trade name AdBlue. The reductant solution is typically introduced into the hot exhaust stream through the use of an injector and converted to ammonia before entering the catalyst. More specifically, the solution is introduced into the hot exhaust stream and, following thermolysis, or thermal decomposition, is converted into ammonia and isocyanic acid (HNCO) in the exhaust gas.The isocyanic acid is then hydrolyzed with the water present in the exhaust gas and converted into ammonia and carbon dioxide (CO2), with the ammonia resulting from the thermolysis and hydrolysis then undergoing a catalyzed reaction with the nitrogen oxides as previously described.

[0004] AUS-32, or AdBlue, has a freezing point of -11° Celsius, and system freezing is expected to occur in cold climates. Because these fluids are aqueous, volume expansion occurs after transitioning to a solid state upon freezing. The expanding solid can exert significant forces on any enclosed volume, such as an injector. This expansion can lead to damage to the injection unit, which is why various SCR strategies exist to address reductant expansion.

[0005] There are two common SCR system strategies on the market: purge systems and purgeless (hereafter referred to as purge-free) systems. In purge SCR systems, the urea reductant and / or DEF solution is purged from the RDU when the vehicle engine is shut down. In purge-free SCR systems, the reductant remains in the RDUs for the life of the vehicle. During normal operation of a purge-free SCR system, the RDU injector operates at temperatures above the reductant's freezing point, so the reductant in the RDU remains in a liquid state. However, when the vehicle engine is shut down in the purge-free SCR system, the RDU injector remains filled with reductant, making the RDU injector vulnerable to damage from reductant expanding under freezing conditions.

[0006] DE 103 34 785 A1 discloses a fuel injector comprising a solenoid coil, a support tube acting as the inner pole of the solenoid coil, and a filter element. The filter element is pressed onto an outer contour of the support tube of the fuel injector. A return spring for urging an armature of the fuel injector is arranged in a recess of the support tube. This return spring is preloaded by an adjusting sleeve, which is also arranged in the support tube.

[0007] DE 10 2013 201 897 A1 discloses a fluid metering valve comprising a flow channel for the fluid leading from a fluid inlet to a metering opening, and a filter device arranged in the flow channel through which the fluid flows. To increase the robustness of the filter device against damage caused by larger particles, the filter device comprises a coarse filter and a fine filter arranged downstream of the coarse filter (in the direction of fluid flow). The fluid metering valve is used as a metering valve for metering a urea-water solution into the exhaust pipe of the internal combustion engine.

[0008] DE 10 2007 008 863 A1 discloses a fuel injector for fuel injection systems of internal combustion engines. The fuel injector comprises an electromagnetic actuating element with a solenoid coil, a core, and a valve jacket as the outer magnetic circuit component, as well as a movable valve closing body that interacts with a valve seat surface associated with a valve seat body. A firm press connection between at least two metallic components of the fuel injector is provided. Summary

[0009] Example embodiments overcome deficiencies identified in existing RDU fluid injectors and provide an improved fluid injector for purge-free SCR systems that reduces the adverse effects of RDU at temperatures below the freezing point of the reductant. According to an example embodiment, an RDU includes a fluid injector having a fluid inlet located at a first end of the fluid injector for receiving a reductant and a fluid outlet located at a second end of the fluid injector for discharging the reductant, the fluid injector defining a fluid path for the reductant from the fluid inlet to the fluid outlet.The fluid injection valve further comprises a tubular element having one end disposed at the fluid inlet of the fluid injection valve, the tubular element being configured to conduct reducing agent along the fluid path, and a filter disposed in the tubular element proximal to the fluid inlet of the fluid injection valve. A volume reduction element is disposed in the tubular element downstream of the filter with respect to a direction of reducing agent flow from the fluid inlet to the fluid outlet of the fluid injection valve, contacts an inner surface of the tubular element, and includes a bore defined by the volume reduction element.The bore defines at least a portion of the fluid path through the fluid injection valve and has a smaller diameter than an inner diameter of the tubular element, such that the volume-reducing element occupies a volume in the tubular element to reduce a volume of the fluid path that the reducing agent can occupy in the fluid injection valve. Furthermore, the fluid injection valve includes a cap element in which the filter is disposed. In an exemplary embodiment, the cap element is connected to the volume-reducing element such that the filter, the volume-reducing element, and the cap form a single element.

[0010] In an exemplary embodiment, the volume-reducing element comprises a first portion and a second portion, wherein the first portion has a smaller outer diameter than an outer diameter of the second portion, and the cap element engages the first portion of the volume-reducing element. The cap element and at least the first portion of the volume-reducing element are formed of metal and / or comprise a metal composition.

[0011] Furthermore, at least a part of the first portion of the volume reducing element is arranged within the cap element, so that an outer diameter of the cap element is equal to the outer diameter of the second portion of the volume reducing element.

[0012] In one exemplary embodiment, the cap element has a press-fit engagement with the first portion of the volume reduction element. In another exemplary embodiment, the cap element is welded to the first portion of the volume reduction element.

[0013] The volume reducing element may include an angled surface between the first portion and the second portion, wherein the angled surface is at an angle other than an angle orthogonal to a longitudinal axis of the volume reducing element.

[0014] In some exemplary embodiments, the first portion and a first part of the second portion of the volume reduction element are made of a metal composition, and a second part of the second portion of the volume reduction element is made of a rubber composition. In an exemplary embodiment, the second part of the second portion of the volume reduction element is over-molded over at least a portion of the first portion of the second portion thereof. Furthermore, the first portion of the second portion of the volume reduction element defines a rim around which the second part of the second portion of the volume reduction element is formed, the rim being located radially inward of the outer diameter of the second portion of the volume reduction element.

[0015] In an exemplary embodiment, the cap member comprises a cylindrically shaped sidewall having first and second axial ends and an annular member extending radially inwardly from the first axial end, and wherein the second axial end of the cap member is circumferentially disposed and engages a portion of the volume reducing member. Short description of the drawings

[0016] In the following, aspects of the invention are explained using an exemplary embodiment in conjunction with the drawings, in which: Fig. 1 is a cross-sectional side view of an RDU for a purge-free SCR system according to an exemplary embodiment; Fig. 2 a cross-sectional side view of a fluid injection valve of the RDU Fig. 1 is; Fig. 3 is an enlarged cross-sectional view of the inlet section of the fluid injection valve of the RDU Fig. 1 according to an exemplary embodiment; Fig. 4 is an exploded perspective view of the components of the fluid injection valve of the RDU Fig. 1 according to an exemplary embodiment; Fig. 5 is an enlarged cross-sectional view of the outlet portion of the fluid injection valve of the RDU Fig. 1 according to an exemplary embodiment; Fig. 6 is an enlarged cross-sectional view of the inlet section of the fluid injection valve of the RDU Fig. 1 according to another exemplary embodiment; Fig. 7 is an exploded perspective view of the components of the fluid injection valve of Fig. 6 is; Fig. 8 a cross-sectional view of the components of Fig. 6 is; Fig. 9 is an enlarged cross-sectional view of the inlet portion of the fluid injection valve of the RDU Fig. 1 according to another exemplary embodiment; Fig. 10 a cross-sectional view of the components of the fluid injection valve of Fig. 9 is; and Fig. 11 is a perspective view of a component of the fluid injection valve of Fig. 9 is. Detailed description

[0017] The following description of the exemplary embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

[0018] Example embodiments generally relate to an RDU for a purge-free SCR system in which harmful effects are reduced by freezing a reductant, DEF and / or urea solution in the RDU injector.

[0019] Fig. 1 illustrates an RDU 10 of a purge-free SCR system according to an exemplary embodiment. RDU 10 includes a solenoid fluid injector, generally designated 12, that provides a fluid metering function and provides injection preparation of the fluid into the exhaust path of a vehicle in a metering application. Thus, fluid injector 12 is constructed and arranged to be associated with an exhaust flow path upstream of an SCR (selective catalytic reduction) catalyst (not shown). Fluid injector 12 may be an electrically operated, solenoid fuel injector. As shown in the Fig. 1 and Fig. 2, the fluid injector 12 includes an actuator having a coil 14 and a movable armature 16. The components of the injector 12 define a fluid path for a reductant, DEF, and / or urea solution through the injector 12. The reductant, DEF, and / or urea solution that the RDU 10 is configured to inject into the exhaust path of a vehicle engine are referred to hereinafter as “reductant” for simplicity.

[0020] The fluid injection valve 12 is arranged in an inner carrier 18 of the RDU 10, as shown in Fig. 1. An injector shield, generally designated 20, is formed by an upper shield 20A and a lower shield 20B surrounding the injector 12 and coupled to the carrier 18 by folding the tabs of a flange 22 of the lower shield 20B over the bearing features of the carrier 18 and the upper shield 20A. This fixes the shield 20 and the carrier 18 with respect to the injector 12.

[0021] An inlet cup structure of RDU 10, generally with 24 in Fig. 1, includes a cup 26 and a fluid supply tube 28 formed integrally with the cup 26. The fluid supply tube 28 is in communication with a source of reductant (not shown) fed into a fluid inlet 30 of the fuel injector 12 for expulsion from a fluid outlet 32 ​​thereof and into the exhaust stream of a vehicle engine (not shown). The fluid inlet 30 of the fuel injector 12 is in fluid communication with the fluid supply tube 28. The fluid outlet 32 ​​is fluidly connected to a flange outlet 34 of an exhaust flange 36 that is directly coupled to one end of the lower shield 20B of RDU 10.

[0022] Injector 12 includes an injector body structure in which the components of injector 12 are arranged. The injector body structure includes a first injector body portion 38, in which coil 14 and armature 16 are arranged, and a valve body portion 40, in which a valve assembly of injector 12 is at least partially arranged. The first injector body portion 38 and the valve body portion 40 are fixedly connected to one another directly or indirectly.

[0023] With reference to the Fig. 1 to 3, the fluid injector 12 includes a tubular member 42 disposed at least partially within the first injector body portion 38. The outer surface of the tubular member 42 contacts the inner surface of the first injector body portion 38. An open end of the tubular member 42 is disposed within the cup 26 and is in fluid communication with the fluid supply tube 28. An O-ring 44 is disposed within the cup 26 between an inner surface thereof and the outer surface of the tubular member 42, proximal to the open end of the tubular member 42. The O-ring 44 serves to ensure that the reductant exiting the fluid supply tube 28 enters the open end of the tubular member 42 of the injector 12.

[0024] The actuating unit of the fluid injection valve 12 further includes a pole piece 46 fixedly disposed within the first injection valve body portion 38. The coil 14 at least partially encloses the pole piece 46 and the armature 16. The pole piece 46 is disposed upstream of the armature 16 in the injection valve 12. The pole piece 46 includes an axially continuous central bore.

[0025] The armature 16 includes a U-shaped section defining a pocket in which at least a portion of a spring 50 is disposed. The spring 50, which is part of the actuating unit, biases the movable armature 16 such that the armature 16 is spaced from the pole piece 46 when no current is conducted through the coil 14. The spring 50 extends partially within the central bore of the pole piece 46. One end of the spring 50 extending within the pole piece 46 contacts a spring adjustment tube 52. The spring adjustment tube 52 is at least partially disposed within the central bore of the pole piece 46 upstream (relative to a flow direction of the reducing agent through the injector 12) of the spring 50. The spring adjustment tube 52 includes an axially through bore.The through-bore of the spring adjustment tube 52 partially defines the fluid path for reductant within the fluid injector 12 and defines the only fluid path for reductant through the pole piece 46. Due to its engagement with the spring 50, the spring adjustment tube 52 is used to calibrate the dynamic flow of reductant through the fluid injector 12.

[0026] The armature 16 further comprises one or more channels 60 ( Fig. 1 and Fig. 2) defined by the armature 16, from an interior of the pocket to an upstream end portion of the pin member 58. The channels 60 may be evenly spaced around the armature 16. In an exemplary embodiment, the armature 16 includes a single channel defined entirely around the base of the pocket formed by the pocket wall 16A. Channel(s) 60 allow reductant to flow from the pocket of the armature 16 into the space around the upstream end of the pin member 58. The pocket of the armature 16 and the channel(s) 60 together partially define the reductant fluid path of the fluid injector 12 and define the only portion of the fluid path that passes through or around the armature 16.

[0027] With reference to the Fig. 1, Fig. 2 and Fig. 5, the valve assembly of the fuel injector 12 includes a sealing member 54 and a seat 56. The sealing member 54 is connected to the armature 16 via a pin member 58 disposed between the sealing member 54 and the downstream end of the armature 16. The sealing member 54, the pin member 58, and the armature 16 may be combined to form an armature assembly. When the coil 14 is energized, the coil 14 generates an electromagnetic force acting on the armature 16, which overcomes the biasing force of the spring 50 and causes the armature 16 to move toward the pole piece 46, which in turn moves the pin member 58 to lift and release the sealing member 54 from the seat 56, moving the armature assembly to an open position and thus allowing the reductant to pass through the fluid outlet 32 ​​to the flange outlet 34 and into the exhaust path of the vehicle engine.When the coil 14 is de-energized, the electromagnetic force is released and the spring 50 biases the armature 16 such that the armature 16 moves away from the pole piece 46, causing the sealing element 54 to sealingly engage the seat 56 and returning the armature assembly to a closed position. When the valve assembly is in the closed position, reductant is prevented from flowing through the seat 56 and the flange outlet 34 into the exhaust path of the vehicle engine.

[0028] As previously mentioned, RDU 10 is part of a purge-free SCR exhaust aftertreatment system. As a result, the reductant remains in fluid injector 12 after the vehicle engine is shut down. In exemplary embodiments, fluid injector 12 is configured to reduce the amount of reductant in fluid injector 12. In other words, the overall volume of the fluid path for reductant through fluid injector 12 is reduced. The reduced space for reductant in injector 12 reduces the amount of reductant in RDU 10 that can potentially freeze, thereby reducing the susceptibility of injector 12 to damage from expansion forces from frozen reductant.

[0029] To reduce the volume of the reductant fluid path in the fluid injector 12, the thickness of the valve body portion 40 is increased. Furthermore, the pin member 58 is designed as a solid member so that reductant flows around the outer surface of the pin member 58 rather than through it. The distance between the outer surface of pin 58 and the inner surface of the valve body portion 40, which partially defines the fluid path for reductant through the injector 12, is reduced. This narrowed portion of the fluid path is the only fluid path for reductant between the armature 16 and the seat 56 in the fluid injector 12.The restricted fluid path between pin 58 and valve body portion 40 provides sufficient reductant flow through fluid injector 12 to perform reductant injection during normal operation of RDU 10, while maintaining a relatively small volume of reductant in injector 12 to reduce the risk of damage to injector 12 due to reductant freezing.

[0030] Furthermore, the diameter of the pocket of the armature 16, in which the spring 50 is at least partially disposed, is reduced, allowing the thickness of the pocket wall 16A of the armature 16 to be increased. In an exemplary embodiment, the thickness of the pocket wall 16A is between 45% and 75% of the pocket diameter, such as approximately 60%. Increasing the thickness of the pocket wall 16A, as well as increasing the thickness of the valve body portion 40 and the pin member 50 as a solid pin, results in the components of the injector 12 being strengthened and thus more resistant to reductant freezing forces.

[0031] Still further, the bore of the spring adjustment tube 52 is sized to reduce the volume of the reductant fluid path in the injector 12. In an exemplary embodiment, the diameter of the bore of the spring adjustment tube 52 is between 12% and 22% of the outer diameter of the pole piece 46, more preferably between 16% and 19% thereof.

[0032] Fig. 3 illustrates an upstream portion of the injector 12. The tubular member 42 extends at least partially through the injector 12. The reductant fluid path through the injector 12 passes through the tubular member 42. The injector 12 includes a filter 204 disposed within the tubular member 42 proximal to its open end. The filter 204 is a structurally rigid, sintered metal filter, such as a stainless steel material, to better withstand the expansion forces upon freezing of reductants. The filter 204 may include a load-bearing outer structure for additional strength. The filter 204, which is best described in Fig. 3, is disposed within a cap member 206. The cap member 206 is generally cylindrical in shape and has a circumferentially extending sidewall 206A defining an interior volume sized to receive the filter 204 therein. The cap member 206 is sized to fit within the tubular member 42, specifically such that the outer surface of the sidewall 206A of the cap member 206 contacts the inner surface of the tubular member 42. The cap member 206 further includes annular members 206B disposed along the axial ends of the cap member 206 and extending radially inward from the sidewall 206A. Annular members 206B serve to retain the filter 204 in a fixed position within the cap member 206. The cap member 206 is made of metal or similar compositions.

[0033] Injector 12 further comprises a retaining ring 207 disposed in the tube member 42 upstream of the cap member 206 and in contact therewith, as shown in Fig. 1 to 3. The retaining ring 207 is attached to the tubular member 42 along an inner surface. The retaining ring 207, which is fixed in position along the tubular member 42, serves to hold the downstream components of the injector 12 in fixed positions within the first injector body portion 38. In an exemplary embodiment, the retaining ring 207 is welded along the inner surface of the tubular member 42. This weld is formed along an entire circumference of the upper edge of the retaining ring 207. However, it should be understood that other connection mechanisms may be used to attach the retaining ring 207 to the tubular member 42.

[0034] With reference to the Fig. 1 to 4, the injection valve 12 further comprises a volume reduction element 208, which serves to further reduce the volume of the reducing agent fluid path in the injection valve 12. The reduction element 208 is, as in Fig. 4, is generally cylindrical in shape and has an upper (upstream) end and a lower (downstream) end. In one embodiment, the volume-reducing element 208 is constructed of a metal, such as stainless steel. However, it should be understood that the volume-reducing element 208 may be formed from other metals or metal compositions. The outer surface of the volume-reducing element 208 is sized to contact the inner surface of the tubular member 42.

[0035] The volume reducing element 208 further comprises a bore 208A ( Fig. 2 and Fig. 3), which is defined in the axial direction by the volume reduction element 208, from one axial (upper) end to the other axial (lower) end. The bore 208A is located along the longitudinal axis of the volume reduction element 208 and is itself part of the fluid path for conducting reductant through the injector 12. The bore 208A forms the only fluid path for conducting reductant through or around the volume reduction element 208. In an exemplary embodiment, the diameter of the bore 208A is between 12% and 20% of the outer diameter of the volume reduction element 208, such as about 16%.Because the volume reducing element 208 extends radially toward the inner surface of the tubular element 42 and the diameter of the bore 208A is small relative to the outer diameter of the volume reducing element 208, the volume reducing element 208 reduces the space or volume in which the reductant can reside within the injector 12, thereby reducing the volume of the reductant fluid path therein. The volume reducing element 208 further assists in holding the spring adjustment tube 52 in position within the injector 12 so that the pin adjustment tube 52 maintains a desired force on the spring 50 to prevent loss of calibration. In particular, the retaining ring 207 maintains the position of the filter 204 and the corresponding cap member 206, which maintain the position of the volume reducing element 208, which maintains the position of the spring adjustment element 52.

[0036] Regarding the Fig. 1-4, the fluid injector 12 further includes a volume compensation element 210 disposed between the lower (downstream) end of the volume reduction element 208 and the top of the pole piece 46. The volume compensation element 210 is made of a resilient material and serves to occupy the space between the volume compensation element 208 and the pole piece 46 to further reduce the volume of the reductant fluid path within the injector 12. The volume compensation element 210, when installed within the injector 12, may be in a compressed state and contact the volume compensation element 208, pole piece 46, the inner surface of the tubular member 42, and the outer surface of the spring adjustment member 52.

[0037] Fig. 5 illustrates a downstream end portion of the fluid injection valve 12. As can be seen, the seat 56 includes a bore defined axially through the seat 56. In an exemplary embodiment, the length of the through-bore of the seat 56 is reduced to further reduce the volume of the reductant fluid path through the seat 56, particularly the pocket volume below the sealing band of the seat 56 that engages the sealing element 54.

[0038] According to an exemplary embodiment, the fluid injection valve 12 includes a plurality of orifice plates 212 arranged in a stacked arrangement. The orifice plate stack is arranged toward the downstream end of the seat 56. In the Fig. In the exemplary embodiment illustrated in Figure 5, the disk stack includes a first disk 212A having one or more openings configured to provide the desired spray pattern of the reductant exiting the injector 12. It is understood that the dimensions and positions of the openings of the first disk 212A may vary and depend on the reductant dosing requirements of the particular vehicle engine. The disk stack further includes a second disk 212B disposed downstream of the first disk 212A and including openings through which the reductant spray passes.The second disc 212B has a greater thickness than the thickness of the first disc 212A and is disposed against the first disc 212A, and supports the first disc 212A to prevent the thinner first disc 212A from deforming due to expansion forces from frozen reductant upstream of the first disc 212A.

[0039] As explained above, the fluid injector 12, and in particular its components, are configured to reduce the volume of the reductant fluid path within the injector 12. In exemplary embodiments, the ratio of the volume of the fluid path within the fluid injector 12 to a volume of the components of the injector 12 (including, but not necessarily limited to, coil 14, armature 16, pole piece 46, spring adjustment tube 52, volume reducing element 208, volume balancing element 210, filter 204, retaining ring 207, spring 50, pin element 58, sealing element 54, seat 56, first injector body portion 20A, and valve body portion 40) is between 0.08 and 0.30, in particular between 0.12 and 0.20, such as about 0.15. These volume quantities are calculated between orthogonal planes relative to the longitudinal axis of the fluid injection valve 12 - from a first plane along the open end of the tubular member 42 (ieof the fluid inlet 30) and a second plane along the lowermost (downstream) surface of the second disk 212B (i.e., the fluid outlet 32). It will be understood that the particular ratio of the reductant path volume to the injector component volume within the fluid injector 12 may vary depending on a number of cost and performance-related factors and may be any value between about 0.08 and about 0.30. Providing a fluid injector with a reduced ratio of reductant fluid path volume to injector component volume to fall within the above range advantageously results in less reductant in the injector 12, which reduces the susceptibility of the RDU 10 to damage if the reductant in the injector 12 freezes.

[0040] In another example, which is shown in the Fig. 6-8, the fluid injection valve 12 includes a volume reducing element 308 which performs many of the functions described above with respect to the Fig. 1-5. Similar to the volume reducing element 208, the volume reducing element 308 is constructed of stainless steel or a similar composition and is disposed in the tubular element 42 of the fluid injection valve 12 between the volume balancing element 210 and the filter 204. However, the volume reducing element 308 includes a first portion 308A and a second portion 308B. As shown in Fig. 7, each of the first portions 308A and second portions 308B has a cylindrical shape, with the outer diameter of the first portion 308A being smaller than the outer diameter of the second portion 308B. The outer diameter of the first portion 308A is smaller than the diameter of the second portion 308B by the thickness of the sidewall 306A of the cap member 306, as will be explained in more detail below. The volume reducing member 308 includes upper (upstream) and lower (downstream) end portions that form the axial ends of the first portion 308A and the second portion 308B, respectively. The outer surface of the second portion 308B is sized to contact the inner surface of the tubular member 42.

[0041] As mentioned, the outer diameter of the first portion 308A of the volume reducing element 308 is smaller than the outer diameter of the second portion 308B thereof. As shown in the Fig. 6-8, the volume reduction element 308 includes an angled annular surface or skirt 308D that extends axially between the outer surface of the first portion 308A and the outer surface of the second portion 308B and serves as a physical interface therebetween. The angle of the angled surface 308D, relative to the longitudinal axis of the volume reduction element 308 and / or the injector 12, is an acute angle. Alternatively, the angle of the angled surface 308D is perpendicular to the longitudinal axis of the volume reduction element 308 and / or the injector 12.

[0042] The volume reduction element 308 further includes a bore 308C defined axially through the volume reduction element 308, from one axial (upper) end to the other axial (lower) end. Bore 308C is located along the longitudinal axis of the volume reduction element 308 and is itself part of the reductant fluid path for conducting the reductant through the injector 12, and is the only reductant fluid path through or around the volume reduction element 308. In an exemplary embodiment, the diameter of the bore 308C is between 12% and 20% of the outer diameter of the volume reduction element 308, such as about 16%.Because the volume reducing element 308 extends to the inner surface of the tubular member 42 and the diameter of the bore 308C is relatively small relative to the outer diameter of the volume reducing element 308, the volume reducing element 308 occupies a volume within the injector 12 that reduces the space or volume of the reductant fluid path through the injector 12 and thereby reduces the amount of reductant in the injector 12 that could freeze and potentially damage the injector 12.

[0043] The cap element 306 includes a number of the same properties of the cap element 206 described above with respect to the Fig. 1-5. As in Fig. 7, the cap member 306 is generally cylindrically shaped, having a sidewall 306A extending circumferentially and defining an interior volume sized to receive the filter 204 therein. The cap member 306 is sized to fit within the tubular member 42, specifically such that the outer surface of the sidewall 306A of the cap member 306 contacts the inner surface of the tubular member 42. The cap member 306 further includes an annular member 306B disposed along the axial (upstream) end of the cap member 306 and extending radially inward from the sidewall 306A. The annular member 306B serves to retain the filter 204 in a fixed position within the cap member 306. Like the cap member 206, the cap member 306 is constructed of metal or similar compositions and serves as structural support for the filter 204.

[0044] In exemplary embodiments, the cap member 306 is engaged and secured to the volume reducing member 308. In this way, the filter 204, cap member 306, and volume reducing member 308 form a single, unitary, and integrated component, as shown in Fig. 8. With a single, unitary component formed from the filter 204, the cap member 306 and the volume reducing member 308 advantageously enable a simpler and less complex process for assembling the injector 12 during its manufacture.

[0045] In the exemplary embodiments, the cap member 306 fits over at least a portion of the first portion 308A of the volume reducing member 308 and is engaged or otherwise secured thereto, as shown in the Fig. 6 and Fig. 8. In one exemplary embodiment, the cap member 306 forms an interference fit with the first portion 308A. In another exemplary embodiment, the cap member 306 is welded to the first portion 308A, such as by a fillet weld between the bottom surface 306C of the cap member 306 and the radially outer surface of the first portion 308A. In each of these embodiments, the angled surface 308D provides sufficient clearance to secure the cap member 306 to the first portion 308A. It should be understood that the cap member 306 may be secured to the first portion 308A of the volume reduction member 308 by other mechanisms.

[0046] With the cap member 306 fitting over the first portion 308A of the volume reducing member 308, the outer diameter of the sidewall 306A is equal to or nearly equal to the outer diameter of the second portion 308A. See Fig. 6 and Fig. 8.

[0047] As explained above, the volume reducing element 308 is made of metal, such as stainless steel, according to an exemplary embodiment. In another exemplary embodiment, a portion of the second section 308B is constructed of plastic or similar compositions. In particular, as shown in Fig. 9-11, the first portion 308A and a first portion 308B-1 of the second portion 308B are formed as a single metal member, with a second portion 308B-2 of the second portion 308B being plastic overmolded around the first portion thereof. Fig. 11 shows the first metal portion 308A and the first portion 308B-1 of the second portion 308B. The first portion 308B-1 of the second portion 308B includes the intermediate portion 308B-3 extending axially (downstream) from the first portion 308A and the distal portion 308B-4 attached to the intermediate portion 308B-3 and extending axially (downstream) therefrom, as shown in Fig.10. The distal portion 308B-4 extends radially farther from a longitudinal axis of the volume reduction element 308 (and / or injector 12) than the radial extension of the intermediate portion 308B-3 to form an edge. The second portion 308B-2 of the second portion 308B, made of over-molded plastic or similar compositions, is formed around the edge formed by the intermediate portion 308B-3 and the distal portion 308B-4 to form the volume reduction element 308 as a single, unitary, and integrated component. As explained above, the volume reduction element 308 is connected to the cap member 306 such that the volume reduction element 308, the filter 204, and the cap member 306 form a single assembly component for mounting the injector 12.

[0048] During assembly of the injector 12, the individual assembly components (filter 204, cap member 306, and volume reduction member 308) are inserted under pressure into the tubular member 42 while contacting the volume compensation member 212. After insertion, and still under pressure, the cap member 306 is welded to the tubular member 42 along its intersection point along the upper portion of the tubular member 42. In one embodiment, the weld is a fillet weld.

Claims

[1] Reductant delivery unit (10) comprising: a fluid injection valve (12) having a fluid inlet (30) arranged at a first end of the fluid injection valve (12) for receiving a reducing agent, and having a fluid outlet (32) arranged at a second end of the fluid injection valve (12) for discharging the reducing agent, wherein the fluid injection valve (12) defines a fluid path for the reducing agent from the fluid inlet (30) to the fluid outlet (32), wherein the fluid injection valve (12) comprises: a tubular element (42) having one end disposed at the fluid inlet (30) of the fluid injection valve (12), the tubular element (42) being configured to conduct reducing agent along the fluid path; a filter (204) disposed in the tubular member (42) proximal to the fluid inlet (30) of the fluid injection valve (12); a volume reducing element (208) arranged in the tubular element (42) downstream of the filter (204) with respect to a direction of the reducing agent flow along the fluid path from the fluid inlet (30) to the fluid outlet (32) of the fluid injection valve (12), wherein the volume reducing element (208) contacts an inner surface of the tubular element (42) and comprises a bore (208A) defined by the volume reducing element (208), wherein the bore (208A) defines at least a portion of the fluid path through the fluid injection valve (12), wherein the diameter of the bore is between 12% and 20% of the outer diameter of the volume reducing element (208) and the volume reducing element (208) occupies a volume in the tubular element (42) such that the volume reducing element (208) reduces a volume of the fluid path occupied by the reducing agent in the fluid injection valve (12); and a cap member (206) in which the filter (204) is arranged, the cap member (206) being engaged with and secured to the volume reducing member (208) such that the filter (204), the volume reducing member (208) and the cap member (206) form a single member. [2] The reducing agent dispensing unit of claim 1, wherein the volume reducing member (208) comprises a first portion and a second portion, the first portion having a smaller outer diameter than an outer diameter of the second portion, and the cap member (206) engaging the first portion of the volume reducing member (208). [3] The reducing agent dispensing unit of claim 2, wherein the cap member (206) and the first portion of the volume reducing member (208) are made of metal. [4] The reducing agent dispensing unit of claim 2, wherein at least a portion of the first portion of the volume reducing element (208) is disposed within the cap element (206) and an outer diameter of the cap element (206) is equal to the outer diameter of the second portion of the volume reducing element (208). [5] The reductant dispensing unit of claim 4, wherein the cap member (206) has a press-fit engagement with the first portion of the volume reducing member (208). [6] Reductant dispensing unit according to claim 4, wherein the cap member (206) is welded to the first portion of the volume reducing member (208). [7] The reductant delivery unit of claim 2, wherein the volume reducing element (208) comprises an angled surface between the first portion and the second portion, the angled surface being at an angle other than an angle orthogonal to a longitudinal axis of the volume reducing element (208). [8] The reducing agent delivery unit of claim 2, wherein the first portion and a first part of the second portion of the volume reducing element (208) are made of a metal composition and a second part of the second portion of the volume reducing element (208) is a plastic composition. [9] The reducing agent delivery unit of claim 8, wherein the second part of the second section of the volume reducing element (208) is overmolded over at least a portion of the first part of the second section thereof. [10] The reductant delivery unit of claim 8, wherein the first part of the second portion of the volume reducing element (208) defines a rim around which the second part of the second portion of the volume reducing element (208) is formed, the rim being disposed radially inwardly of the outer diameter of the second portion of the volume reducing element (208). [11] The reductant delivery unit of claim 1, wherein the cap member (206) comprises a cylindrically shaped sidewall having first and second axial ends and an annular member (206B) extending radially inwardly from the first axial end, and wherein the second axial end of the cap member (206) is circumferentially disposed and engages a portion of the volume reducing member (208). [12] Fluid injection valve (12), comprising: a fluid inlet (30) arranged at a first end of the fluid injection valve (12) for receiving a fluid, and a fluid outlet (32) arranged at a second end of the fluid injection valve (12) for expelling the fluid, wherein the fluid injection valve (12) defines a fluid path from the fluid inlet (30) to the fluid outlet (32); a tubular member (42) having one end disposed at the fluid inlet (30) of the fluid injection valve (12), the fluid path extending through the tubular member (42); a filter (204) disposed in the tubular member (42) proximal to the fluid inlet (30) of the fluid injection valve (12); a volume reducing element (208) arranged in the tubular element (42) downstream of the filter (204) with respect to a direction of fluid flow from the fluid inlet (30) to the fluid outlet of the fluid injection valve (12), the volume reducing element (208) contacting an inner surface of the tubular element (42) and comprising a bore (208A) defined by the volume reducing element (208), wherein the diameter of the bore is between 12% and 20% of the outer diameter of the volume reducing element (208) and the volume reducing element (208) occupies a volume in the tubular element (42) such that the volume reducing element (208) reduces a volume of the fluid path in the fluid injection valve (12); and a cap element (206) in which the filter (204) is arranged, wherein the cap element (206) is attached to the volume reducing element (208) such that the filter (204), the volume reducing element (208) and the cap element (206) form a single mounting element. [13] The fluid injection valve (12) of claim 12, wherein the volume reducing element (208) comprises a first portion and a second portion, the first portion having a smaller outer diameter than an outer diameter of the second portion, and the cap member (206) is attached to the first portion of the volume reducing element (208). [14] The fluid injection valve (12) of claim 13, wherein the first portion of the volume reducing element (208) is disposed within the cap element (206) and an outer diameter of the cap element (206) is equal to the outer diameter of the second portion of the volume reducing element (208). [15] The fluid injection valve (12) of claim 13, wherein the cap member (206) has a press-fit attachment to the first portion of the volume reducing member (208). [16] Fluid injection valve (12) according to claim 13, wherein the cap member (206) is welded to the first portion of the volume reducing member (208). [17] The fluid injection valve (12) of claim 13, wherein the volume reducing element (208) comprises an angled surface between the first portion and the second portion, the angled surface being at an angle other than an angle orthogonal to a longitudinal axis of the volume reducing element (208). [18] The fluid injection valve (12) of claim 13, wherein the first portion and a first part of the second portion of the volume reducing element (208) are made of a metal composition and a second part of the second portion of the volume reducing element (208) is a plastic composition. [19] The fluid injection valve (12) of claim 18, wherein the second part of the second section of the volume reducing element (208) is overmolded over a part of the first part of the second section of the volume reducing element (208), the first part of the second section of the volume reducing element (208) defining a rim around which the second part of the second section of the volume reducing element (208) is formed, the rim being arranged radially inwardly of the outer diameter of the second section of the volume reducing element (208). [20] The fluid injection valve (12) of claim 12, wherein the fluid injection valve (12) is part of a reductant delivery unit (10), and wherein the cap member (206) comprises a cylindrically shaped sidewall having first and second axial ends and an annular member extending radially inwardly from the first axial end, and wherein the second axial end of the cap member (206) is disposed around the volume reducing member (208) and engages a portion of the volume reducing member (208).

Images