Injector for injecting a reagent

Abstract

Injector (100) for injecting a reagent, the injector (100) comprising: a housing (102, 104); an axially displaceable valve element (130) positioned within the housing (102, 104); an electromagnet (200) positioned within the housing (102, 104) and having a wire coil (202) circumscribing at least a portion of the valve element (130), the valve element (130) moving between a seated position and an unseated position in response to energization of the electromagnet (200); a flux frame (207) surrounding the coil (202), the frame having first and second radially extending portions (214, 264) axially spaced from each other and extending along substantially parallel planes positioned on opposite sides of the coil (202); a flux sleeve (220) having two magnetic flux bridge collar sections (224, 226) connected by either a magnetic flux bridge section (228') or a non-magnetic flux break section (228), each of the two magnetic flux bridge collar sections (224, 226) being intersected by one of the planes (216, 266) in which the radially extending flux frame sections lie to define flux bridges, the flux bridge section or the flux break section being surrounded by the coil (202) and positioned axially between the parallel planes (216, 266); a tubular rod piece (164) disposed within the housing (102, 104), the rod piece (164) defining a return channel (184) for reagent flow when the valve element (130) is in the seated position and / or the unseated position; and a filter (302) positioned within the housing (102, 104) and surrounding the rod piece (164), the filter (302) comprising a cage (306) and a mesh (304) attached to the cage (306), the mesh (304) covering windows (364) extending through the cage (306), the cage (306) having a deformable first seal (320) biasedly engaging an outer surface of the rod piece (164), the cage (306) having a second seal (330) biasedly engaging the housing (102, 104), the first and second seals (320, 330) defining a closed volume between the housing (102, 104) and the filter (302) such that the entire flow through the injector (100) flowing reagent flows through the mesh (304).

Description

AREA

[0001] The present disclosure relates to injector systems and, more particularly, to an injector system for injecting reagent, such as an aqueous urea solution, into an exhaust gas stream to reduce nitrogen oxide (NO x -) To reduce emissions from diesel engine exhaust. BACKGROUND

[0002] This section provides background information to the present disclosure, which is not necessarily prior art. Lean-burn engines provide improved fuel efficiency by operating with an excess of oxygen, i.e., an amount of oxygen greater than that required to completely combust the available fuel. Such engines are said to be running "lean" or with a "lean mixture." However, this improved or increased fuel economy compared to combustion in non-lean engines is offset by undesirable pollutant emissions, particularly in the form of nitrogen oxides (NO x ), lifted.

[0003] One to reduce NO x The process used to reduce emissions from lean-burn engines is known as selective catalytic reduction (SCR). For example, when SCR is used to reduce NO x-emissions of a diesel engine, an atomized reagent is injected into the engine exhaust stream depending on one or more selected engine operating parameters, such as exhaust temperature, engine speed or engine load, measured by the engine fuel flow, turbo boost pressure or exhaust NO x -mass flow, injected. The reagent / exhaust gas mixture is passed through a reactor containing a catalyst, for example activated carbon, or metals such as platinum, vanadium or tungsten, which are capable of reducing the NO x -concentration in the presence of the reagent.

[0004] Aqueous urea solution is known to be an effective reagent in SCR systems for diesel engines. However, the use of such an aqueous urea solution has many disadvantages. Urea is highly corrosive and can adversely affect mechanical components of the SCR system, such as the injectors used to inject the urea mixture into the exhaust stream. Urea can also solidify when exposed to high temperatures for extended periods, such as those found in diesel exhaust systems. Solidified urea accumulates in the narrow passages and exit orifices typically found in injectors. Solidified urea can also cause fouling of injector moving parts and clog any orifices or urea flow paths, thereby rendering the injector unusable.

[0005] In addition, if the urea mixture is not finely atomized, urea deposits form in the catalytic reactor, inhibiting the action of the catalyst and thereby reducing the effectiveness of the SCR system. High injection pressures are one way to minimize the problem of insufficient atomization of the urea mixture. However, high injection pressures often result in the injector spray plume penetrating too deeply into the exhaust stream, causing it to impinge on the inner surface of the exhaust pipe opposite the injector. Excessive penetration also leads to inefficient use of the urea mixture and reduces the area in which the vehicle can operate with reduced NO x-emissions. Only a finite amount of aqueous urea can be carried on a vehicle, and what is carried should be used efficiently to maximize the vehicle's range and reduce the need for frequent reagent refills.

[0006] Various known reagent injectors incorporate a solenoid valve for metering the reagent feed into the exhaust stream. Typically, a magnetic movable element of the valve is urged to shift between an open and closed position as an electromagnet is selectively switched on and off. The electromagnets of many earlier injectors exhibit multiple flux distributions, resulting in a poorly defined magnetic circuit. Reagent valve control may not be optimal with these types of magnetic circuits. The actual amount of reagent delivered to the exhaust system may deviate from a target reagent injection rate, resulting in inefficient use of the on-board reagent.The time required for the valve to switch from a closed state to an open state and back to a closed state may be longer than desired due to the arrangement of the magnetic circuit.

[0007] Furthermore, aqueous urea is a poor lubricant. This property adversely affects the moving parts within the injector and requires relatively tight or small fits, clearances, and tolerances between adjacent or relatively moving parts within an injector. Aqueous urea also has a high tendency to leak. This property adversely affects joined surfaces and requires increased sealing resources in many locations.

[0008] DE 11 2013 002 372 T5 describes an injection device with an axially movable valve element arranged in a housing. An electromagnet is arranged in the housing and has a wire coil arranged near the valve element, so that the valve element moves between a position adjacent to a valve seat and a position lifted from the valve seat in response to energization of the electromagnet. A connector connected to the housing has an inlet tube concentrically aligned with and surrounding a return tube. The inlet tube is adapted to receive a pressurized reagent from a reagent source. The return tube is adapted to return the reagent to the source.

[0009] DE 11 2013 002 360 T5 describes an injector for injecting a reagent into an exhaust gas stream, comprising an outer tube extending through an electromagnet and surrounding an inner tube. A first end of the inner tube is sealingly attached to an inner surface of the outer tube. A guide element and an orifice plate are each sealingly attached to the inner surface of the outer tube. A second end of the inner tube is aligned by the guide element. A movable valve element includes a pin head guided by the inner surface of the outer tube to align the valve element with an opening extending through the orifice plate.

[0010] DE 10 2005 035 347 B3 describes a fuel injector for internal combustion engines, which has an axial bore in a nozzle body through which fuel flows and which accommodates a nozzle needle guided axially displaceably in the nozzle body. The nozzle needle has a seating surface in the nozzle body at one end and carries a bushing at its other end that sits on the circumference of the nozzle needle and is displaceable relative to the nozzle needle. The bushing, resiliently supported on the nozzle needle, delimits a control chamber in contact with a component of the fuel injector axially adjoining the nozzle body. The control chamber communicates with the fuel-flow chamber on the outside of the bushing via an inlet channel in the bushing and has an outlet channel controlled by a control valve.

[0011] JP H05 - 10 221 A describes a solenoid fuel injection valve for preventing injection continuity due to residues or foreign matter by arranging a filter in a fuel path formed by a needle valve and a nozzle body in a solenoid fuel injection valve, wherein by energizing a solenoid coil, a needle valve and also a movable core are moved towards a fixed core.

[0012] It may be advantageous to provide an improved electromagnetically controlled injector with a well-defined magnetic circuit to improve the control of reagent injection.

[0013] Methods and apparatus of the present disclosure provide the foregoing and other advantages. SUMMARY

[0014] This section provides a general summary of the disclosure and is not a comprehensive disclosure of its entire scope or all of its features.

[0015] An injector for injecting a reagent includes an axially displaceable valve element positioned within a housing. A flow sleeve is surrounded by a coil of an electromagnet. A rod end defines a return channel for the reagent flow. A filter surrounds the rod end and includes a cage and a mesh attached to the cage. The cage includes a deformable first seal biased to engage an outer surface of the rod end. The cage includes a second seal biased to engage the housing. The first and second seals define a closed volume such that all reagent flowing through the injector passes through the mesh.

[0016] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are for purposes of illustration only and are not intended to limit the scope of the present disclosure. DRAWINGS

[0017] The drawings described herein are intended to illustrate selected embodiments only and not all possible implementations and are not intended to limit the scope of the present disclosure. Fig. 1 is a schematic illustrating an exemplary exhaust aftertreatment system having an electromagnetically controlled flux bridge and flux break reagent injector according to the teachings of the present disclosure; Fig. 2 is a perspective view of the electromagnetically controlled reagent injector; Fig. 3 is an exploded perspective view of the reagent injector; Fig. 4 is a cross-sectional view through the Fig. 2 and Fig. 3 shown injector; Fig. 5 is an enlarged cross-sectional view illustrating the magnetic flux density of an embodiment having a one-piece magnetic section extending between the two magnetic sections of the flux sleeve; Fig. 6 is a cross-sectional view of an injector having a cage filter; Fig. 7 is a perspective view of the Fig. 6 shown cage filter; Fig. 8 is a fragmentary cross-sectional view of a portion of the injector including the cage filter; and Fig. 9 is a fragmentary cross-sectional view of another portion of the injector including the cage filter.

[0018] In the several views of the drawings, corresponding reference numerals indicate corresponding parts throughout. DETAILED DESCRIPTION

[0019] Exemplary embodiments will now be described in more detail with reference to the accompanying drawings.

[0020] It should be noted that, although the present teachings are related to diesel engines and the reduction of NO xemissions, the present teachings may be used in connection with any one of several exhaust streams, such as, by way of non-limiting example, those from diesel, gasoline, turbine, fuel cell, jet, or any other energy source that emits an exhaust stream. In addition, the present teachings may be used in connection with the reduction of any one of several undesirable emissions. For example, the injection of hydrocarbons for the regeneration of diesel particulate filters is also within the scope of the present disclosure. For further description, reference is made to commonly assigned patent US 8 047 452 B2 entitled "Method And Apparatus For Injecting Atomized Fluids," which is incorporated herein by reference.

[0021] With reference to the figures, a pollutant removal system 8 for reducing NO x-Emissions from the exhaust of a diesel engine 21. In Fig. 1, solid lines between the elements of the system indicate fluid lines for reagent, while dashed lines indicate electrical connections. The system of the present teachings may include a reagent tank 10 for receiving the reagent and a delivery module 12 for delivering the reagent from the tank 10. The reagent may be a urea solution, a hydrocarbon, an alkyl ester, alcohol, an organic compound, water, or the like, and may be a mixture or combination thereof. It should also be noted that one or more reagents may be available in the system and may be used individually or in combination. The tank 10 and the delivery module 12 may form an integrated reagent tank / delivery module. Also provided as part of the system 8 are an electronic injection control unit 14, a reagent injector 16, and an exhaust system 18.The exhaust system 18 has an exhaust line 19 which provides an exhaust gas flow to at least one catalyst bed 17.

[0022] The delivery module 12 may include a pump that supplies reagent from the tank 10 via a supply line 9. The reagent tank 10 may be made of polypropylene, epoxy-coated carbon steel, PVC, or stainless steel and may be sized depending on the application (e.g., vehicle size, intended use of the vehicle, and the like). A pressure regulator (not shown) may be provided to maintain the system at a predetermined pressure setpoint (e.g., relatively low pressures of approximately 60 to 80 psi, or in some embodiments, a pressure of approximately 60 to 150 psi) and may be disposed in the return line 35 from the reagent injector 16. A pressure sensor may be present in the supply line 9 leading to the reagent injector 16. The system may also include various anti-freeze strategies to thaw frozen reagent or prevent the reagent from freezing.During system operation, regardless of whether the injector is releasing reagent into the exhaust gases, reagent may be continuously circulated between the tank 10 and the reagent injector 16 to cool the injector and minimize the reagent residence time in the injector to keep the reagent cool. For temperature-sensitive reagents, such as aqueous urea, which tend to solidify at the elevated temperatures of 300°C to 650°C encountered in an engine exhaust system, continuous reagent circulation may be required.

[0023] Furthermore, it may be desirable to keep the reagent mixture below 140°C, and preferably within a lower operating range between 5°C and 95°C, to ensure that solidification of the reagent is prevented. If solidified reagent is allowed to form, it can contaminate the moving parts and openings of the injector.

[0024] The required amount of reagent can be varied with the load, exhaust gas temperature, exhaust gas flow, engine fuel injection timing, desired NO x reduction, barometric pressure, relative humidity, EGR rate, and engine coolant temperature. A NO x Sensor or measuring device 25 is positioned downstream of the catalyst bed 17. The NO x -Sensor 25 is operational, the exhaust NO x -content to an engine control unit 27. All or some of the engine operating parameters may be transmitted from the engine control unit 27 to the electronic reagent injection control 14 via the engine / vehicle data bus. The electronic reagent injection control 14 could also be included as part of the engine control unit 27. The exhaust gas temperature, exhaust flow, exhaust back pressure, and other vehicle operating parameters may be measured by respective sensors.

[0025] With reference to Fig. 2 to 4, the reagent injector 100 will now be further described. The reagent injector 100 includes an injector outer body 102 having an upper outer body portion 102a and a lower outer body portion 102b. The lower outer body portion 102b may have a deformable section 103 pressed against the upper outer body portion 102a. An elongated lower inner body 104 may be received within the upper outer body portion 102a and / or the lower outer body portion 102b. The elongated lower inner body 104 defines a cylindrical central bore 106 in fluid communication with an orifice plate 108 to define at least one exit orifice 110 extending completely through the orifice plate 108.

[0026] The orifice plate 108 may be coupled to and retained within the lower outer body portion 102b by means of an orifice plate retainer 112. If desired, the orifice plate retainer 112 may be formed integrally with the lower inner body 104. Alternatively, as shown in the figures, the orifice plate retainer 112 is separately formed to include a reduced diameter portion 114 spaced from an inner wall 116 of the lower outer body portion 102b. A fluid supply channel 118 is formed therebetween. The reduced diameter portion 114 is hollow and receives a reduced diameter end portion 120 of the lower inner body 104. The plate retainer 112 may be attached to the lower inner body 104 and the lower outer body portion 102b by a process such as electron beam welding.The orifice plate support 112 also includes a central bore 124 coaxially aligned with the central bore 106 and having a smaller inner diameter than the central bore 106. A plurality of channels 125 extend through the plate support 112 to fluidly connect the channel 118 to a cavity 126 formed between the reduced diameter end portion 120 and the central bore 124.

[0027] A valve element 130 is slidably mounted within the central bore 106. The valve element 130 includes an elongated stem 132 with a conical first end 134 and an opposite second end 136. The conical end 134 is selectively engageable with a valve seat 140 to define a sealed, closed position of the valve element 130 when seated. An unsealed, open position exists when the stem 132 is lifted from the valve seat 140. The valve seat 140 surrounds the outlet opening 110. The valve seat may be conical or tapered, as shown, to complement the shape of the conical end 134 of the stem 132 to limit the flow of reagent through the opening 110.Depending on the application and operating environment, the bolt 132 and orifice plate 108 may be made from a carbide material that provides the desired performance characteristics and is easier and more cost-effective to manufacture. In addition, limitations or disadvantages associated with other materials, such as those associated with manufacturing complex part shapes, can be avoided. Carbide may offer additional advantages, such as insensitivity to brazing temperatures, which can range from 870 to 980°C, unlike carbon steels and tool steels, which may lose hardness. Carbide may also provide increased surface hardness compared to that achievable with most other steels. Carbide may also be advantageous in terms of overall wear resistance.

[0028] A bolt head 142 is attached to the end 136 of the bolt 132. The bolt head 142 is slidably positioned within an enlarged bore 144 of the lower inner body 104. A sliding class fit between the bolt head 142 and bore 144 provides an upper guide for the valve element 130. A lower valve element guide is formed on the sliding surface between the central bore 124 and the pintle 132. Based on this arrangement, the valve element 130 is precisely aligned with the valve seat 140 and the outlet opening 110.

[0029] A bottom surface 150 of the bolt head 142 is spaced from a surface 152 of the lower inner body 104 to form a cavity 154 that is in fluid communication with the cavity 126 via a channel 158 defined as a portion of the central bore 106 not occupied by the bolt 132. A channel 160 extends through the bolt head 142 to define a portion of a reagent return channel.

[0030] A rod section 164 having a first end 166 is sized to be received within the bore 144. The first end 166 of the rod section 164 is secured to the lower inner body 104 by a process such as electron beam welding. An opposite second end 168 of the rod section 164 is sealingly fitted within a bore 172 formed in the upper outer body portion 102a. A seal 176 separates an inlet port 178 from an outlet port 180 within the upper outer body portion 102a. The elongated rod section 164 has a central bore 184 extending therethrough. The central bore 184 is coaxially aligned with the central bore 106. Extending inwardly from the second end 168 of the rod piece 164 is a counterbore 188 which is coaxially aligned with a counterbore 190 extending into the bolt head 142.A compression spring 194 is positioned in the counterbores 188, 190 to urge the valve element 130 into engagement with the seat 140.

[0031] An electromagnet assembly 200 is positioned within the lower outer body portion 102a, as shown in the figures. The electromagnet assembly 200 may include a plastic 201 molded over to encapsulate the other components of the electromagnet assembly 200 therein. The electromagnet assembly 200 includes a wire coil 202 wound around a bobbin 204. A two-piece flux frame 207 includes a first frame half 208 attached to a second flux frame half 210, which are positioned to circumferentially surround the wire 202 and the bobbin 204. The bolt head 142 is constructed of a magnetic material such as 430 stainless steel such that electrical energization of the coil 202 creates a magnetic field that urges the bolt head 142 toward the rod piece 164. The end 134 of the bolt 132 detaches from the seat 140 to allow reagent flow through the outlet opening 110.The coil 202 can be energized via access to a connector socket 211, for example in response to a signal from the electronic injection controller 14. The electronic injection controller 14 receives sensor input signals and determines when to inject reagent into the exhaust stream to effect selective catalytic reduction of NO. x -emissions.

[0032] Controller 14 also defines the reagent injection duration and reagent injection rate. Depending on the engine operating condition, load, ambient air temperature, exhaust gas temperature, and other factors, it may be desirable to control injector 100 to provide a relatively wide range of reagent injection rates. To achieve this goal, it may be desirable to minimize the total time associated with moving pin 132 from a seated position to an open position and back to the seated position. Precise control of the position of pin head 142 can be achieved by providing a well-defined magnetic circuit.

[0033] The flux frame half 210 includes a radially extending portion 214 extending generally along a transverse line 216. The bolt head 142 includes an enlarged diameter portion 218 intersected by line 216. Both the flux frame half 210 and the bolt head 142 are constructed from a magnetic material. To further define the magnetic circuit, the lower inner body 104 is constructed from a non-magnetic material, such as 304 stainless steel. A portion of the lower inner body 104 intersected by line 216 has a minimum cross-sectional thickness to minimize any disruption of the magnetic flux.

[0034] A fluid sleeve assembly 220 is illustrated as a three-piece assembly having a first flow bridge collar 224 and a second flow bridge collar 226, which in some embodiments are connected by a flow break 228 or, in some embodiments, by a flow bridge 228'. The fluid sleeve assembly 220 is formed as an elongated hollow cylindrical member sized and positioned to define a portion of the inlet channel 178. First and second seals 232, 234 ensure that pressurized reagent continues to flow through the inlet channel 178 and does not enter the solenoid assembly 200. The flow bridge collars 226 and 224 are substantially similar and include a counterbore having a first cylindrical inner surface 238 with a first reduced inner diameter and a second cylindrical inner surface 240 defining a second, larger inner diameter.The outer surface of each flux collar is also stepped and includes a cylindrical surface 242 with a larger outer diameter than a second cylindrical surface 244. The flux break or flux bridge 228 is a substantially right-hand circular cylinder having an inner surface 248 that engages and is secured to each reduced-diameter outer surface 244. The outer surface 242 engages or is only minimally spaced from walls 252 and 254 that define circular openings extending through the flux frame halves 210, 208. The first cylindrical inner surface 238 of the flux bridge collar 224 is sized to fit snugly against the lower inner body 104 and minimize any air gap intersected by line 216.

[0035] The first cylindrical inner surface 238 of the flux bridge collar 226 is sized to cooperate with an enlarged diameter portion 260 of the rod piece 164. The flux frame half 208 has a radially inwardly extending portion 264 extending along a line 266. The enlarged diameter portion 260 and the flux bridge collar 226 are axially positioned to align with the line 266 and provide a magnetic circuit path across the injector 100. The flux frame halves 208 and 210 are constructed of a magnetic material such as 1018 low carbon steel. The flux bridge collars 224 and 226 are constructed of 430 ferritic stainless steel. The rod piece 164 is made of 430 ferritic stainless steel or a similar magnetic material. The bolt head 142 may be made of ferritic stainless steel 430.In some embodiments, the flux break 228 is made of non-ferritic and non-magnetic 304 stainless steel, as is the lower inner body 104. Constructing the above-described components from magnetic and non-magnetic materials and positioning the magnetic materials close to each other along lines 216 and 266 significantly improves the magnetic circuit performance associated with the electromagnet assembly 200. Advantages may include the use of smaller coil wire, a fewer number of wire turns, and a lower amount of electrical current to achieve an improved electromagnetic actuator with lower cost, size, and mass. Furthermore, improved control of the position of the valve element 130 is realized.It should also be noted that the transverse planes defined by the ends of the cylindrical wire coil 202 can be interpreted as part of the magnetic circuit, as can the planes containing lines 216 and 266. At least one of these transverse planes intersects the bolt head 142, the flux bridge collars 224, 226, and the enlarged diameter rod portion 260.

[0036] In some embodiments, the flux bridge 228' is made of a magnetic material such as ferritic stainless steel 430. In this embodiment, the flux bridge 228' is magnetic, as are the flux bridge collars 224, 226. Constructing the above-described components from magnetic and non-magnetic materials and positioning the magnetic materials close to each other along lines 216 and 266 significantly improves the magnetic circuit performance associated with the electromagnet assembly 200, as shown in Fig. 5. Advantages may include the use of smaller coil wire, a fewer number of wire turns, and a lower amount of electrical current to achieve an improved electromagnetic actuator with lower cost, size, and mass. Improved control of the position of the valve element 130 is also realized. It should also be noted that the transverse planes defined by the ends of the cylindrical wire coil 202 can be interpreted as part of the magnetic circuit, as can the planes containing lines 216 and 266. At least one of these transverse planes intersects the bolt head 142, the flux bridge collars 224, 226, the flux bridge 228', and the enlarged diameter rod portion 260.

[0037] As in Fig. 5, in some embodiments, the flow bridge collars 224, 226 and the flow bridge 228' may be a single unitary element. In this way, the flow bridge collars 224, 226 and the flow bridge 228' represent sections or regions of a continuous element. In some embodiments, the flow bridge collars 224, 226 and the flow bridge 228' may comprise a plurality of individual elements arranged and oriented similarly to the flow bridge collars 224, 226 and the flow break 228. Embodiments employing the flow bridge 228' extending between the flow bridge collars 224 may define improved and / or increased flux density along the flow bridge 228'. To further improve and / or increase flux density, in some embodiments, the length of the enlarged bore 144 of the lower inner body 104 may be shortened, as shown in Fig. 5 compared to Fig. 4 is illustrated.

[0038] A reagent fluid path is defined within the injector 100 when the bolt 132 is in the closed position. The fluid path ensures circulation of fluid through the injector 100. Specifically, the reagent fluid path extends from an inlet 270 of the upper outer body portion 102a through an inlet filter 268 and the inlet channel 178 with a gap between an outer surface of the rod piece 164 and the upper outer body portion 102a, through the fluid sleeve assembly 220, the fluid channel 118, the paths formed in the plate holder 112 by the cavity 126, the channel 158, the channel 160, the central bore 184, the outlet channel 180, a throttle opening 272, an outlet filter 274 to the exit outlet 278. Typically, reagent entering the inlet 270 initially has a relatively cool temperature compared to the exhaust gas passing through the exhaust system in close proximity to the opening 110. 18 flows.The recirculation of reagent through the injector 100 transfers heat from the orifice plate 108 and the orifice plate support 112. The recirculation of reagent also assists in the transfer of heat from the coil 202 because the coil body 204 is placed in close contact with the reagent flowing fluid sleeve assembly 220.

[0039] When coil 202 is electrically energized, a magnetic field is generated, urging bolt head 142 against the biasing force of spring 194 to release bolt end 134 from its seat. Pressurized reagent located in cavity 126 flows between bolt 132 and seat 140 and through exit port 110 to inject reagent into an exhaust stream flowing through exhaust system 18. Solenoid assembly 200 may be controlled by any number of methods, including pulse width modulation, to open and close exit port 110 at a predetermined frequency.

[0040] In one in the Fig. 6 to 9, an injector 300 is constructed substantially similarly to the injector 100 defined above. To avoid repetition, only the differences between the embodiments will be discussed in detail. It should be noted that the description of similar components as in the Fig. 1 to 5 also applies to the injector 300.

[0041] The injector 300 includes a cage filter 302, which may be provided in addition to or instead of the inlet filter 268 and / or the outlet filter 274. The cage filter 302 includes a porous filter 304 attached to a cage 306. The filter 304 is a substantially hollow cylindrical element configured to allow injected urea to flow through it, but to prevent contaminants from flowing further through the injector 300. The cage 306 includes a substantially cylindrical hollow body 308 having a first end 310 and an opposite second end 312. The cage 306 includes an end wall 316 positioned at a first end 310. An opening 318 extends through the end wall 316. The end wall 316 has an integrally formed first lip seal 320 which is Fig.8. Viewed in cross-section, the thickness of the end wall 316 decreases from a cylindrical outer surface 322 to an inner peripheral surface 324 that defines the opening 318. The first lip seal 320 is configured to flex and / or plastically and / or elastically deform slightly when attached to the rod piece 164' to sealingly engage a cylindrical outer surface 328 of the rod piece 164' in an interference fit.

[0042] The cage 306 includes a radially outwardly extending flange 330 formed integrally with the body 308 and positioned at the second end 312. The flange 330 extends radially outward and axially away from the body 308 at an angle of approximately 45 degrees. A cylindrical outer surface 334 of the flange 330 is sized to provide an interference fit with a cylindrical inner surface 336 of a bore 338 of an injector housing 340, described above as the upper outer body portion 102a. The flange 330 defines a second seal that acts as a lip seal. The flange 330 plastically and / or elastically deforms to form an interference fit with the cylindrical inner surface 336.

[0043] Flange 330 includes a seat 342 positioned in engagement with fluid sleeve assembly 220'. Fluid sleeve assembly 220' is constructed substantially similarly to fluid sleeve assembly 220 in that it is a three-piece assembly with flux bridge collars 224' and 226' at opposite ends constructed of ferritic 430 stainless steel or a similar ferritic material. Flux bridge collars 224' and 226' are connected by a flux break 228" or, in some embodiments, a flux bridge 228". Flux break 228" is constructed of a non-ferritic and non-magnetic 304 stainless steel or a similar material. Flux bridge 228" is constructed similarly to flux bridge collars 224', 226'.

[0044] The flux bridge collar 224' has first and second radially extending flanges 346, 348, respectively. The first flange 346 engages the seat 342 of the cage filter 302. The first flange 346 is axially offset from one end of the first flux bridge collar 224' such that an axially extending portion 350 of the first flux bridge collar 224' serves to guide and align the cage 306.

[0045] It is conceivable that the cage 306 is constructed of nylon 6.6 with 30% glass reinforcement. The mesh may be constructed of a metal or a plastic. In the present example, the mesh 304 is constructed of nylon 6.6 with openings approximately 40 micrometers in size therethrough. The body 308 has a plurality of windows 364 extending therethrough. Each window is covered by a portion of the mesh 304. To pass through the cage filter 302, a fluid must flow through the mesh 304.

[0046] Furthermore, the foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. From this discussion and the accompanying drawings and claims, one skilled in the art will recognize that various changes, modifications, and variations may be made without departing from the spirit and scope of the disclosure as defined in the following claims.

Claims

[1] Injector (100) for injecting a reagent, the injector (100) comprising: a housing (102, 104); an axially displaceable valve element (130) positioned within the housing (102, 104); an electromagnet (200) positioned within the housing (102, 104) and having a wire coil (202) circumscribing at least a portion of the valve element (130), the valve element (130) moving between a seated position and an unseated position in response to energization of the electromagnet (200); a flux frame (207) surrounding the coil (202), the frame having first and second radially extending portions (214, 264) axially spaced from each other and extending along substantially parallel planes positioned on opposite sides of the coil (202); a flux sleeve (220) having two magnetic flux bridge collar sections (224, 226) connected by either a magnetic flux bridge section (228') or a non-magnetic flux break section (228), each of the two magnetic flux bridge collar sections (224, 226) being intersected by one of the planes (216, 266) in which the radially extending flux frame sections lie to define flux bridges, the flux bridge section or the flux break section being surrounded by the coil (202) and positioned axially between the parallel planes (216, 266); a tubular rod piece (164) disposed within the housing (102, 104), the rod piece (164) defining a return channel (184) for reagent flow when the valve element (130) is in the seated position and / or the unseated position; and a filter (302) positioned within the housing (102, 104) and surrounding the rod piece (164), the filter (302) comprising a cage (306) and a mesh (304) attached to the cage (306), the mesh (304) covering windows (364) extending through the cage (306), the cage (306) having a deformable first seal (320) biasedly engaging an outer surface of the rod piece (164), the cage (306) having a second seal (330) biasedly engaging the housing (102, 104), the first and second seals (320, 330) defining a closed volume between the housing (102, 104) and the filter (302) such that the entire flow through the injector (100) flowing reagent flows through the mesh (304). [2] The injector (100) of claim 1, wherein the first and second seals (320, 330) are formed integrally with the cage (306), the cage (306), the first seal, and the second seal (320, 330) defining a one-piece structure. [3] The injector (100) of claim 2, wherein the cage (306) is molded onto the braid (304). [4] The injector (100) of any one of claims 1 to 3, wherein the first seal (320) extends radially inward from the braid (304) and the second seal (330) extends radially outward from the braid (304). [5] Injector (100) according to one of claims 1 to 3, wherein the braid (304) is formed as a hollow right-hand circular cylinder. [6] The injector (100) of any one of claims 1 to 3, wherein the cage (306) has a cup-shaped structure with the first seal (320) positioned at an end opposite the second seal (330). [7] The injector (100) of any one of claims 1 to 3, wherein the cage (306) is constructed of nylon 6,6. [8] Injector (100) according to one of claims 1 to 3, wherein the first seal (320) and the second seal (330) are deformable lip seals. [9] Injector (100) according to one of claims 1 to 3, wherein the second seal (330) is formed as a radially outwardly extending flange forming a 45-degree angle with a longitudinal axis of the injector (100). [10] The injector (100) of any one of claims 1 to 3, wherein the rod portion (164) extends through the entire filter (302) and projects in any direction beyond the axial extent of the filter (302). [11] Injector (100) according to one of claims 1 to 3, wherein the flow sleeve (220) comprises three coaxially aligned tubes connected together. [12] The injector (100) of any one of claims 1 to 3, wherein the flux sleeve (220) is a continuous member having the two magnetic flux bridge collar portions (224, 226) and either the magnetic flux bridge portion (228') or the non-magnetic flux break portion (228). [13] The injector (100) of any one of claims 1 to 3, wherein the reagent is directed to flow through the flow sleeve (220). [14] The injector (100) of any one of claims 1 to 3, wherein the valve element (130) comprises a cylindrical bolt coupled to an enlarged bolt head, the bolt head being made of a magnetic material and positioned such that one of the planes intersects the bolt head when the valve element (130) is in the seated position. [15] The injector (100) of any one of claims 1 to 3, wherein the tubular rod portion (164) forms an interference fit with the first seal, with the second seal and the housing (102, 104) defining a further interference fit.

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