US20140054396A1

US20140054396A1 - Fluid injector

Info

Publication number: US20140054396A1
Application number: US13/621,838
Authority: US
Inventors: Nicholas Jeremy Scull
Original assignee: International Engine Intellectual Property Co LLC
Current assignee: International Engine Intellectual Property Co LLC
Priority date: 2012-08-21
Filing date: 2012-09-17
Publication date: 2014-02-27

Abstract

An injector for controllably injecting a fluid into an exhaust stream having a housing that defines a chamber for storing the fluid and a metering orifice defined by an annular flow passage in fluid communication with the chamber. A valve member is movable between closed and open positions for controlling the flow of fluid from the chamber, through the annular flow passage, and into the exhaust stream.

Description

RELATED APPLICATIONS

This application claims priority to U.S. Application Ser. No. 61/691,495, having a filing date of Aug. 21, 2012, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

Emission standards around the world continue to place stricter limits on emissions from diesel engines, particularly those in over-the-road vehicles, such as trucks. In order to provide consumers with engines that comply with these standards, manufacturers often employ after-treatment systems that are configured to capture pollutants and/or convert them into acceptable emission constituents.
For example, diesel particulate filters (DPFs) are commonly used to remove particulate matter, e.g., soot, from engine exhaust flow. A DPF has a structure that permits exhaust gases to flow through the filter while trapping solid particulate matter. Over time, the accumulated particulate matter can reduce the efficiency of the filter. Accordingly, various methods are used to clean or “regenerate” the filter to its original state by burning off the trapped particulate matter.
One method for cleaning the DPF is referred to as “active regeneration.” In active regeneration, the exhaust gas temperature is increased to levels to “burn off” the accumulated particulate matter in the DPF. For example, an injector (commonly referred to as “closer”) can be used to periodically inject diesel fuel (or other reagent) into the engine exhaust upstream of the DPF. The injected fuel is burned to raise the temperature of the exhaust gas entering the DPF to a level sufficient to burn off the accumulated soot. In some systems, the elevated temperature of the exhaust gas entering the DPF may be generated in a diesel oxidation catalyst (DOC) located upstream of the DPF. The doser injects fuel exhaust stream upstream of the DOC. The DOC consumes the fuel, resulting in an exothermic reaction in the DOC, which elevates the temperature of the exhaust gas flowing downstream to the DPF to approximately and/or above 550° C., causing the “burn off” event and DPF regeneration.
Similarly, selective catalytic reduction (SCR) can be used to reduce NO_xemissions from diesel engines, for example. SCR involves injecting an atomized reagent, such as ammonia or urea, into the engine exhaust stream. The reagent/exhaust gas mixture is passed through a catalyst, which reduces NO_xconcentration in the presence of the reagent.
Injectors that are used for DPF regeneration and SCR typically inject the reagent directly into the engine exhaust flow. As such, these injectors can be exposed to harsh operating conditions, including elevated temperatures and contaminants within the exhaust stream. In such an environment, soot can accumulate in and around the tip of the injector. With time, the soot build up can lead to a reduced flow through the injector, poor atomization, or even a complete loss of flow if the injector becomes completely covered, or plugged. This phenomena is commonly referred to in the art as “injector fouling.”

SUMMARY

Embodiments depicted herein disclose an injector for injecting fluid, such as diesel fuel, ammonia, urea or other reagent, into an engine exhaust stream while reducing the occurrence of injector fouling.
In at least one aspect, the presently described technology involves an injector for controllably injecting a fluid into an exhaust stream having a housing that defines a chamber for storing the fluid and an orifice defined by an annular flow passage in fluid communication with the chamber. A valve member is movable between closed and open positions for controlling the flow of fluid from the chamber, through the annular flow passage, and into the exhaust stream. In some embodiments and at lest one aspect of the present technology, the annular flow chamber is interposed between the chamber and the valve member.
According to further embodiments, the valve member can include valve seat formed in an outer surface of the injector that faces the exhaust stream. The valve member can include a valve head that is movable between closed and open positions. At its closed position, the valve head blocks fluid flow through annular flow passage. At its open position, the valve head is spaced away from the valve seat in the direction of the exhaust stream to permit fluid flow through the annular flow passage.
In still further embodiments, the valve member seals the orifice from exhaust gas flow when the valve member is in its closed position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an injector in accordance with at least one embodiment of the present technology.

FIG. 2 is an exploded perspective view of a body subassembly from the injector of FIG. 1.

FIG. 3 is an exploded perspective view of an armature subassembly from the injector of FIG. 1.

FIG. 4 is an exploded perspective view of a valve subassembly from the injector of FIG. 1.

FIG. 5A is a cross-sectional view of the valve subassembly along line A-A of FIG. 1.

FIG. 5B is a partial perspective view of the valve subassembly.

FIG. 6 is perspective view of a valve seat in accordance with at least one embodiment of the present technology.

FIG. 7 is a cross-sectional view of the valve seat along line B-B of FIG. 6.

FIG. 8A is a cross-sectional view of the injector of FIG. 1, showing the injector in its closed position.

FIG. 8B is a cross-sectional view of the injector of FIG. 1, showing the injector in its open position.

FIG. 9 is a cross-sectional view of the injector taken along line C-C of FIG. 8A.

FIG. 10 is an enlarged detail of the injector indicated at D on FIG. 9A

FIGS. 11A and 11B illustrate a discharge passage and annular flow passage according to certain embodiments of the present technology.

FIGS. 11C and 11D illustrate a discharge passage and annular flow passage according to certain other embodiments of the present technology.

FIGS. 11E and 11F illustrate a discharge passage and annular flow passage according to certain other embodiments of the present technology.

FIGS. 12A-12H is the injector of FIGS. 11A and 11B at various stroke lengths.

FIG. 13 is a cross-sectional view of an injector according to at least one embodiment of the present technology.

FIG. 14 is a perspective view illustrating a method for connecting injector of FIG. 12 to an exhaust component.

FIGS. 15A and 15B are a cross-sectional views of an injector according to at least one embodiment of the present technology.

FIG. 16 is a schematic of a hydraulic circuit that can be used to supply fluid to an injector in accordance with at least one embodiment of the present technology.

DETAILED DESCRIPTION

FIG. 1 is an exploded perspective view of an injector 10 in accordance with at least one embodiment of the present technology. The injector 10 can be used, for example, to inject a fluid into the exhaust stream of a diesel engine. In the context of the present technology, fluid can include a liquid, gas and/or mixture thereof. In some embodiments, the fluid can be diesel fuel, which is, for example, injected into the exhaust stream for use in active regeneration of a DPF. In other, embodiments, the fluid can be ammonia or urea, which is injected into the exhaust stream for use in an SCR. While the injector is described in the context of exhaust aftertreatment, it will be understood and appreciated by those skilled in the art that the injector can be used to inject and/or otherwise dispense one or more fluids in a variety of other environments, including but not limited to dispensing chemicals in chemical applications, preservatives in food, insecticides, pesticides or herbicides in agricultural or other applications, or other fluids capable of being dispensed in the presently described technology; water treatment applications; industrial and/or commercial spraying applications, such as spray drying, spray pyrolysis, and spray freeze drying; fire suppression systems; gas conditioning applications; and humidity control systems and applications.
The injector 10 generally includes a coil subassembly 12, a body subassembly 14, an armature subassembly 16, a stator 18 and a valve subassembly 20. The injector can also, for example, include a mounting feature for securing the injector to an exhaust component (not shown). According to at least one embodiment, the mounting feature includes a mounting bracket 13, a pair of fasteners 15, such as bolts, and a pair of spacers 17. The spacers 17 include reduced diameter proximal portions 19 that are configured to engage into reciprocal apertures 21 in the mounting bracket 13. With the spacers 17 so installed in the mounting bracket 13, the fasteners 15 can be inserted through the spacers 17. The proximal ends of the fasteners 15 extend through the spacers 17 (and the apertures 21 in the mounting bracket 13) and can be threaded into reciprocal apertures (not shown) in the exhaust component (not shown) for securing the injector 10 to the exhaust component.
The coil subassembly 12, further includes a coil 22 wound around a bobbin 24 and a cover 26 that fits over the bobbin 24.
Referring additionally to FIG. 2, the body subassembly 14 includes a main body 28, a tube 30 and a fitting 32. A longitudinal passage 34 extends through the main body 28. A proximal end 36 of the tube 30 is mounted to a distal end 38 of the main body 28. The tube 30 includes a longitudinal passage 40 that is concentric with the longitudinal passage 34 of the main body 28. In the illustrated embodiment, the tube 30 is mounted to the main body 28 by inserting the tube 30 into an enlarged diameter counterbore 42 (see FIG. 8A) formed in the distal end 38 of main body 28, concentric with the longitudinal passage 34. The fitting 32 mounts on distal end 43 of the tube 30 opposite the main body 28 and includes a longitudinal passage 44 that is concentric with the longitudinal passages 34, 40 of the main body 28 and the tube 30. In the illustrated embodiment, the fitting 32 includes a reduced diameter portion 46 that is sized for insertion into the distal end 43 of the tube 30. The main body 28, tube 30 and fitting 32 can be made of stainless steel, for example, and can be secured together by suitable methods such as threaded connections, press-fitting, welding, brazing or crimping.
Referring additionally to FIG. 3, the armature subassembly 16 includes an armature 50 and first and second pins 52, 54 that extend from opposite ends of the armature. The first pin 52 is inserted into a bore 56 in proximal end 58 of the armature 50, while the second pin 54 is inserted into a bore 60 in the distal end 62 of the armature 50. In some embodiments, the armature 50 can be formed of a ferromagnetic material such as steel, while the pins can be formed from a non-ferromagnetic material such as stainless steel. The pins 52, 54 can be secured to the armature 50 by suitable methods such as threaded connections, press-fitting, welding, brazing or crimping, for example. The armature 50 can include a plurality of flat portions 64 and curved (or radiused) portions 66 extending longitudinally between the proximal and distal ends 58, 62 of the armature 50. As discussed in greater detail below, the curved portions 66 allow the armature 50 to freely slide within the tube 30, while the flat portions 64 define fluid passages that allow fluid to flow around the armature 50. The armature 50 can be constructed, for example, by turning a multi-sided piece of bar stock to produce an armature with alternating flat and curved portions 64, 66. For example, a hexagonal bar stock can be turned to produce an armature with six (6) flat portions and six (6) curved portions. In some embodiments, the armature 50 can have a circular cross section and one or more flow passages can extend longitudinally through the armature.
Referring now to FIGS. 4-7, the valve subassembly 20 includes a plunger or pintel 70, an adapter 72, a valve body 74, a bias means, such as a spring 76, and a retainer 78. The valve body 74 includes a proximal portion 80 that is sized for insertion into a central opening 82 in the adapter 72. When the injector 10 is connected to an exhaust component, the adapter 72 and the proximal portion 80 of the valve body 74 can be be directly exposed to the exhaust gases flowing through the exhaust component. Accordingly, the adapter 72 and at least the proximal portion 80 of the valve body 74 should be constructed from materials that are suitable for exposure to the elevated temperatures and contaminants within the exhaust stream of an engine, for example. In this regard, the adapter 72 and valve body 74 can be formed from a corrosion resistant material such as stainless steel, for example. The adapter 72 and valve body 74 can be secured together by suitable means such as threaded connection, press-fitting, brazing, crimping and/or welding. According to at least one embodiment, the adapter 72 and valve body 74 are both formed from stainless steel and are brazed together. Heat from the brazing (or from other heat treating process) can be used to heat treat the adapter 72 and the valve body 74 in order to harden these components for wear resistance. Following the brazing/heat treating process, these components can be tempered to make them less brittle.
A longitudinal passage or bore 84 extends through the valve body 74's proximal and distal ends 86, 88. The plunger 70 is sized for insertion into the proximal end of the longitudinal passage 84. Proximal end 90 of the plunger 70 includes a tapered or conical shaped valve head 92 that is configured to mate with a valve seat 94 formed in the proximal end 86 of valve body 74. The interface between the valve head 92 and valve seat 94 forms a seal such as a line seal. The distal end 96 of the plunger 70 extends through longitudinal passage 84 beyond the distal end 88 of the valve body 74.
The spring 76 mounts concentrically over the distal end 96 of the plunger 70 and is secured in place by the retainer 78. According to at least one embodiment, the retainer 78 can be generally disc-shaped and can include a center opening 98 that is configured to mount on a reduced diameter portion 100 of the plunger 70. As can be seen in FIG. 5B, a slot 102 extends outwardly from the opening 98 on the retainer 78. During assembly, the plunger 70 is inserted distally through longitudinal passage 84 until the valve head 92 abuts the valve seat 94. In some embodiments, the center section of the plunger defines a bearing surface 155 (see FIG. 4) that forms a close, free-sliding fit with the longitudinal passage 84. It will be noted that it is desirable to have a relatively small (or tight) clearance between this bearing surface 155 and the wall of the passage 84 to center the plunger within the passage 84.
The spring 76 is then slid over the distal end 96 of the plunger 70. The retainer 78 is then installed by compressing the spring 76 and sliding the retainer 78 laterally (via the slot 102) over the reduced diameter portion 100 of the plunger 70 until the center opening 98 is positioned on the reduced diameter portion 100. When the retainer 78 is properly positioned, the spring 76 can be released. The force of the spring 76 seats the retainer 78 against an enlarged taper 104 at the distal end of the reduced diameter portion 100, thereby securing the retainer (and spring) on the plunger 70. The force of the spring 76 against the retainer (and hence the plunger) normally biases the injector 10 to its closed (or seated position). As explained below, the coil 22 can be energized to move the plunger 70 (against the force of the spring 76) to an open or unseated position.
Referring again to FIG. 1 and also to FIGS. 8A and 8B, the injector 10 can be assembled by first positioning the mounting bracket 13 on the body subassembly 14. For this purpose, the mounting flange 13 includes an aperture 105 sized to slide over the main body 28.
Once the mounting bracket 13 is positioned on the main body 28, the coil subassembly 12 can be mounted on the body subassembly 14. To this end, the bobbin 24 includes a longitudinal passage 105 that is sized to slide over the fitting 32 and the tube 30. The bobbin 24 includes proximal and distal annular flanges 108, 110 that function to retain the coil 22 on the bobbin 24. Once the bobbin 24 is in place on the tube 30, the cover 26 can be slid proximally over the bobbin 24 until its proximal end engages with the distal end of the main body 28. In the illustrate embodiment, the proximal end of the cover 26 is sized to slide over a reduced diameter distal portion 116 of the main body 28. As can be seen in FIG. 8A, when the cover 26 is so mounted on the body subassembly 14, the mounting bracket 13 and bobbin 24 are secured in place between the main body 28 and an inwardly extending annular wall 118 formed at the distal end of the cover 26. The tube 30 projects distally beyond the annular wall 118. A spring clip 122 can be slid over the tube 30 and against the annular wall 118 to secure the coil assembly 12 onto the body subassembly 14. Alternatively or additionally, the cover 26 can be secured to the main body 28 by threaded connections, press-fitting, welding, brazing, crimping or other suitable means. As can be seen in FIG. 8A, a pair of electrical conductors 124, e.g., wires, extend from the coil 22 and through the cover 26 for connection to an external electrical circuit (not shown) for energizing/deenergizing the coil 22 to control operation of the injector 10. The injector 10 can include an electrical connector 126 that is configured to mate with a reciprocal electrical connector (not shown) from the external circuit to electrically interconnect the injector and the circuit.
Once the coil subassembly 12 is mounted on the body subassembly 14, the armature subassembly 16 can be slid through the distal end of the longitudinal passage 34 in the main body 28 and into the longitudinal passage 40 of the tube 30. As the armature subassembly 16 slides into the tube 30, the second pin 54 slidably engages with the longitudinal passage 44 in the fitting 32. Once the armature subassembly 16 is positioned within the tube 30, the stator 18 can be inserted into the longitudinal passage 34 in the main body 28. As the stator 18 is slide into place, the first pin 52 of the armature subassembly 16 slidably engages into a longitudinal passage 132 in the stator. The interfaces between the first and second pins 52, 54 and the longitudinal passages 132, 44 function to center the armature 50 within the tube 30 and facilitate its movement relative thereto. The stator 18 includes a distal portion 127 that extends into the proximal end of the tube 30. The stator 18 also includes an annular flange 128 that abuts against a stop 130 formed in the longitudinal passage 34 of the main body 28. With the stator 18 so installed, the stator 18 and fitting 32 function as proximal and distal stops, respectively, to limit movement of the armature 50 within the tube 30, and accordingly the stroke of the injector 10.
Once the stator 18 is installed, the valve subassembly 20 can be mounted onto the proximal end of the main body 28. To this end, the adapter 72 includes and annular flange that is configured to mate with a counterbore 136 formed in the proximal face of the main body 28 concentric with the longitudinal bore 34. The adapter 72 (and hence the valve subassembly 20) can be secured to the main body 28 by welding, brazing, crimping, press-fitting, threaded connections, or other suitable means.
It will be appreciated by at least those skilled in the relevant art that the method of assembly of the injector 10 can be varied and/or modified. For example, the order in which the components are assembled can be changed or varied. Alternatively or additionally, the connections and/or interfaces between the various components can be varied and/or combined. For example, in the illustrated embodiment, the spacers 17 are separately formed from the mounting bracket 13. The spacers 17 can, alternatively, be integrally formed with the mounting bracket 13. Similarly, the mounting bracket 13 can be integrally formed with another injector component, such as the body subassembly 14, for example.
According to at least some further embodiments of the present technology, the injector 10 is biased to its closed position as shown in FIG. 8A when the coil 22 is deenergized (i.e., off). Specifically, when the coil 22 is off, the spring 76 biases the plunger 70 proximally relative to the valve body 74 and causes the valve head 92 to seat against the valve seat 94. Alternatively, in some embodiments, the injector is normally biased to its open position. For example, the injector 10 can be constructed so that the spring 76 normally biases the plunger 70 to its open position and the coil 22 is energized to move, e.g., pull the plunger to its closed position (against the force of the spring). In such embodiments, the plunger can be integral with, or otherwise connected to, the first pin 52.
According to at least some embodiments, the injectable fluid, e.g., diesel fuel, ammonia or urea, circulates through the injector in order to cool the injector components and particularly components that are adjacent or near the flow of exhaust gas. To that end, the injector 10 includes an inlet port 138 and an outlet port 140 that are interconnected by a cooling path (as detailed below). In the illustrated embodiment, the inlet port 138 is formed in the main body 28, while the outlet port 140 is formed in the fitting 32. Fluid flows through the inlet port 138 and into an annular chamber 142 formed between main body 28, the stator 18 and the valve subassembly 20. Fluid from the annular chamber 142 flows through a set of first flow passages 144 formed in the valve body 74 (see, e.g., FIGS. 5A, 6, 7 and 9) and into a discharge passage 146.
When the valve subassembly 20 is closed, fluid flows through the annular chamber 142 to cool the proximal portion of the plunger 70 (including its valve head 92) and the proximal portion of the valve body 74. Fluid from the annular chamber 142 also flows through a set of second flow passages 148 and into a spring chamber 149 defined by the stator 18 (see, e.g., FIGS. 6 and 10). At least one flow passage 150 extends through the distal end of the stator 18 and interconnects the spring chamber 149 with the interior of the tube 30. When the coil is off (deenergized), the spring 76 biases the injector to its closed position, i.e., the valve head 92 is seated against the valve seat 94. When this occurs, the plunger 70 acts against the first pin 52 moving the armature 50 distally (e.g., to the right in FIG. 8A) in the tube 30 and away from the distal face of the stator 18. When the armature 50 is disengaged from the stator 18 (as shown in FIG. 8A), fluid flows from spring chamber 149 through the flow passage 150 and into the tube 30. The fluid then flows distally around the armature 50 (through the flow passages defined by the flat portions 64).
Additionally, the fitting 32 includes lateral flow passages 152 that intersect with the longitudinal passage 44. Fluid flows from the tube 30, into the lateral flow passages 152, through the longitudinal passage 44 and out of the injector through the outlet port 140. The fitting 32 can include an orifice 154 in the longitudinal passage 44 for controlling the rate of fluid flow through the injector's cooling path. In the illustrated embodiment, the orifice 154 is formed separately from the fitting 32 and is configured to mount in, e.g., thread into, the longitudinal passage 44. By forming the orifice 154 separately from the fitting 32, the flow rate can be adjusted by placing different orifices in the fitting. Alternatively, the orifice 154 can be integrally formed with the fitting.
In sum, when the injector 10 is closed, fluid flows through the inlet port 138 and into the annular chamber 142. Fluid from the annular chamber 142 flows into the discharge passage 146 (through the first passages 144) and also into the spring chamber 149 (through the second flow passages 148). When the injector 10 is closed, the armature 50 is biased distally in the tube 30 and out of engagement with the face of the stator 18. As a result, fluid from the spring chamber 149 flows through the longitudinal passage 150 and into the tube 30. The fluid then flows distally around the armature 52 (through the flow passages defined by the flat portions 64), into the lateral passages 152, through the longitudinal passage 44 (and orifice 154) and out of the injector 10 through the outlet port 140. The flow of fluid (e.g. diesel fuel) in the manner just described cools the proximal components of the injector (e.g., plunger, valve body, spring, or adapter among others), which helps, fore example, prevent soot accumulation and maintains the desired performance characteristics of the injector's components.
When the injector 10 is moved to its open position i.e., the valve head 92 is unseated from valve seat 94 (see FIG. 8B), by energizing the coil 22. When the coil 22 is energized, the flux path created by the coil acts on the armature 50 to move it proximally (e.g., to the left in FIG. 8B) within the tube 30. As the armature 50 moves proximally in the tube, the first pin 52 pushes against the plunger 70 (and against the force of the spring 76) to unseat the valve head 92 from the valve seat 94. When the valve head 92 unseats from the valve seat 94, fluid flows from the discharge passage 146, through a discharge or metering orifice 159 (see, e.g., FIG. 11A), out through the gap between the valve head 92 and the valve seat 94, and into the exhaust stream. The use of an outwardly moving (or opening) plunger 70 beneficially functions to reduce soot build up on the injector tip. In particular, the outward movement of the valve head 92 relative to the valve body 74 tends to dislodge soot that would otherwise accumulate at the junction between the valve head 92 and the valve seat 94.
In some embodiments, the cooling path can be closed or otherwise modified when the injector is opened. For example, in some embodiments, when the injector is open, the armature 50 seats against the distal face of the stator 18 to close the flow passage 150. Closing the cooling flow passage to prevent flow out of the fitting 32 can be beneficial, for example, when there is limited flow and/or pressure available from the external fluid source, e.g., from a supply pump. Further, when the injector 10 is open, the fluid that is ejected from the valve subassembly 20 cools the proximal components.
In still further embodiments, the discharge passage 146 is defined by the volume bounded by the wall 164 of longitudinal passage 84 in the valve body 74 and a reduced diameter portion 172 of the plunger 70. As discussed above, fluid flows from the annular chamber 142 and into the discharge passage 146 through the flow passages 144 in the valve body 74. Flow passages according to at least one embodiment of the present disclosure are shown in FIGS. 7 and 9. As illustrated, the flow passages 144 can be axially offset from the longitudinal passage 84 of the valve body 74. Offsetting the flow passages 144 in the manner shown creates a swirling flow of fluid within the discharge passage 146. This swirling flow provides, for example, even fluid distribution and balances the pressure within the discharge passage 146. As a result, when the injector opens, fluid from the discharge passage 146 discharges evenly through the metering orifice 159, resulting in a uniform and well-distributed spray of fluid from the injector. Further, according to some embodiments, the inner ends 147 of the flow passages 144 can be radiused (as shown) to increase flow efficiency and performance. While the illustrated embodiment includes six flow (or swirl) passages 144, it will be appreciated that the number of passages can be varied. In addition, while the flow passages 144 all have a uniform offset from the longitudinal passage 84, it should be appreciated that the passages can have no offsets, uniform offsets, varying offsets, and/or combinations thereof.
According to at least some embodiments, the metering orifice 159 is formed by a passage that controls the flow rate between the discharge passage 146 and the passage bounded by the valve head 92 and the valve seat 94. Moreover, in some embodiments, the metering orifice 159 is defined by an annular flow passage 160 at this location. FIGS. 11A and 11B illustrate an annular flow passage 160 according to some embodiments of the present technology. In these embodiments, the annular flow passage 160 is defined by an annular gap between an annular flange 162 on the plunger 70 and the wall 164 of the longitudinal passage 84 in the valve body 74. The plunger 70 can include an annular groove 184 adjacent to the valve head 92. The groove 184 can function to increase the volume downstream of the annular flow passage 160, thereby increasing the pressure drop across the flow passage 160 and increasing exit velocity. As noted above, the center section of the plunger includes a bearing surface 155. It will be noted that it is desirable to have a tight clearance between this bearing surface and the wall of the passage 84 to ensure centering of the plunger within the passage 84. As can be seen in FIGS. 11A and 11B, a relatively larger clearance can be provided between the plunger 70 and the wall of the passage 84 in the region defining the annular flow passage 160.
FIGS. 11C and 11D, illustrate a discharge passage 146 and annular flow passage 160 according to certain other embodiments of the present technology. In these embodiments, the longitudinal passage 84 in the valve body 74 includes an increased diameter portion 168 in its proximal end, while the plunger 70 has a generally constant diameter, except for an increased diameter portion 170 at its proximal end adjacent to the valve head 92. Although not shown, the plunger 70 can include an annular groove adjacent to the valve head 92 to increase the volume downstream of the annular flow passage 160, thereby increasing the pressure drop across the flow passage 160 and increasing exit velocity. In these embodiments, the discharge passage 146 is defined by the space between the constant diameter portion 173 of the plunger 70 and the increased diameter portion 168 of the longitudinal passage 84. It should be noted that the constant diameter portion 173 of the plunger 70 can also function as a bearing surface 155 in the manner described above. Likewise the annular flow passage 160 is defined by the annular gap between the increased diameter portion 170 of the plunger 72 and the increased diameter portion 168 of the longitudinal passage 84.
FIGS. 11E and 11F, illustrate a discharge passage 146 and annular flow passage 160 according to certain other embodiments of the present technology. In these embodiments, the plunger 70 can exhibit a generally constant diameter along its length except for the valve head 92. The plunger 70 can include an annular groove 184 adjacent to the valve head 92 to increase the exit velocity in the manner discussed above. The longitudinal passage 84 in the valve body 74 can exhibit a generally constant diameter, except for an increased diameter interior portion 180. The discharge passage 146 is defined by the annular space between the plunger 70 and the increased diameter inner portion 180 of the passage 84. The annular flow passage 160 is defined by the annular gap between the plunger 70 and the portion 182 of the longitudinal passage 84 that is located proximal to (i.e., outwardly from) the increased diameter interior portion 180. A portion of the plunger 70 can also function as a bearing surface 155 in the manner described above in to ensure centering of the plunger within the passage 84. Accordingly, it is desirable to have a tight clearance between this bearing surface 155 and the portion 187 of the passage 182 that interfaces with the bearing surface. Further, as can be seen in FIGS. 11E and 11F, a relatively larger clearance can be provided between the plunger 70 and the wall of the passage 84 in the portion 182 of the passage 84 defining the annular flow passage 160.
The discharge passage 146 and metering orifice 159 (e.g., annular flow passage 160) can be sized and configured in accordance with the desired performance characteristics or desired applications and/or environments. For example, a relatively small discharge passage 146 can act as a flow restrictor on the orifice 159. In particular, if the cross-sectional area of the discharge passage is smaller than that of the metering orifice 160, e.g., annular flow passage 160, the discharge passage 146 will restrict the maximum flow rater through the orifice 159. Conversely, increasing the size of the discharge passage 146 increases volume of fluid that is stored in the discharge passage when the injector 10 is closed. An increased volume of stored fluid can increase the momentum, e.g., by the fluid from the external fluid source, required to initiate injection. Accordingly, in some embodiments, the discharge passage 146 can be sized and configured so that it does not restrict fluid flow through the metering orifice 159, while still providing adequate control over the start of injection. It may be desirable to provide a volume for the passage 146 such that all of the volume of passage 146 is purged each cycle/operation of the device, to assure that no fluid remains in passage 146 from one cycle to the next to reduce the potential for formation of deposits in passage 146 associated with the high heat exposure of the fluid residing within passage 146. It may also be desirable to provide passage 146 with a small volume to reduce or minimize loss of angular momentum of the fluid between the swirl plate and the annular orifice 160.
A relatively high exit velocity from the annular flow passage 160 is beneficial for better fuel atomization. Accordingly, in some embodiments, the injector 10 can be configured to maximize the velocity of fluid exiting the annular flow passage 160. The exit velocity from the annular flow passage 160 can be increased by increasing the pressure drop across the annular flow passage 160. In some embodiments, the exit velocity from the annular orifice 160 is increased by increasing the pressure drop across the annular flow passage 160. One way to increase this pressure drop is by increasing the pressure in discharge passage 146, which can be accomplished by reducing flow restrictions upstream of the discharge passage. Accordingly, in some embodiments, the pressure in the discharge passage 146 is maximized by minimizing upstream flow restrictions. The pressure drop across the annular flow passage 160 can also be increased by reducing the length of the annular flow passage. However, while decreasing the length of the annular flow passage 160 tends to increase exit velocity, it can also make the injector more sensitive to manufacturing tolerances. Accordingly, in some embodiments, the length of the annular flow passage 160 is minimized, within the constraints of manufacturing tolerances, in order to increase exit velocity from the flow passage.
The cross-sectional area and length of the annular flow passage 160, i.e., the metering orifice 159, can be empirically determined during design and manufacture in order to provide the desired injection characteristics, including, for example, injection flow rate and distribution. In this regard, increasing the annular cross-sectional area of the flow passage 160 will generally increase fluid flow fluid flow, but will also tend to decrease the velocity of fluid flow. Likewise, the length of the annular flow passage 160 can be empirically determined during design and manufacture in order to provide the desired injection characteristics. For example, in the embodiments of FIGS. 11A and 11B, the longitudinal passage 84 in the valve body 74 has a constant diameter (at least in the region that defines the annular flow passage 160). Accordingly, the length of the annular flange 162 on the plunger 72 can set the length of the annular flow passage 160. In these embodiments, the annular flange 162 can be sized (e.g., its length can be set) such that the stroke (i.e., normal operating range) of the injector 10 can vary without causing any significant change in the performance, e.g., spray uniformity and distribution, of the injector. Accordingly, the cross-sectional area of the annular flow passage 160 is generally constant over the normal operating range of the injector.
This concept is further illustrated in FIGS. 12A-12H, which illustrate the operation of an injector having an annular flow passage 160 constructed in accordance with the embodiments of FIGS. 11A-B. The stroke length or lift, e.g., the distance the plunger moves proximally from its closed position, continually increase between FIGS. 12A and 12H. As the stroke length increases, the annular gap 200 between the valve head 92 and the valve seat 94 increases. If the stroke length is too short, the gap 200 can restrict fluid flow through the annular flow passage 160 (or orifice). (See, e.g., FIG. 12A). Accordingly, in some embodiments, the stroke is set so that when the injector is fully open the cross-sectional area of the gap 200 is larger than that of the annular flow passage 160.
The length of the annular flow passage 160 can be decreased to increase the velocity of fluid flow through the passage 160. As noted above, increase fluid velocity through the passage 160 can provide increased atomization of the fluid that is discharged from the injector. In the embodiments represented by FIGS. 11A and 11B, for example, the length of the annular flow passage 160 can be controlled by the stroke of the plunger 70. In particular, this length decreases as stroke length increases. At some point, the length of the flow passage 160 can become too short to provide good flow control and characteristics from the annular flow passage 160. In particular, as this length of the passage 160 decreases, the ability to maintain a constant cross sectional area for the annular flow passage can become more sensitive to manufacturing tolerances. As this occurs, the performance, e.g., flow rate, of the injector may begin to fluctuate with stroke length. Further, as the distal end of the annular flange 162 moves proximally past junction of the valve seat 94 and the passage 84, the cross-sectional area will continue to increase with increasing outward movement of the plunger. Accordingly, in some embodiments, the length of the annular flow passage is minimized, within manufacturing tolerances, while the cross-sectional area of the flow passage is held constant.
Accordingly, the stroke length and annular flow passage 160 can be set, e.g., through empirical testing during design and manufacture, in order to provide the desired injector operating characteristics. Further, according to some embodiments, proportional control can be used to provide variable flow from the injector. For example, proportional control can be used to adjust the stroke length (i.e., plunger lift) and accordingly the length of the annular flow passage 160.
As shown in the drawings, the annular flow passage 160 is located inwardly from the valve seat 94. Accordingly, when the injector 10 is closed, the annular flow passage 160 is protected from exposure to the exhaust stream by the seal between the valve head 92 and the valve seat 94, thereby reducing, for example, soot accumulation and injector fouling. Injector fouling is further reduced because fluid flows out of the annular flow passage 160 whenever the plunger 70 is open. This constant outward fluid flow prevents contaminates from entering and/or flushes contaminants form the injector, thereby reducing injector fouling.
FIG. 13 illustrates a water-cooled injector 1010 according to at least one embodiment of the present technology. The injector 1010 includes many components that are the same or similar to those used in the injector 10 of FIG. 1. Unlike the injector 10 of FIG. 1, however, the injector 1010 uses a cooling fluid, such as water, instead of the injectable fluid, e.g., diesel fuel, to cool the injector components. To that end, the injector 1010 includes a cooling flange 1300 mounted on the proximal end of the injector. As explained further below, the cooling flange 1300 circulates cooling fluid around the injector components that are adjacent or near the flow of exhaust gas in order to cool these components.
Like the injector 10 of FIG. 1, the injector 1010 includes a coil subassembly 1012, a body subassembly 1014, an armature subassembly 1016 and a valve subassembly 1020. The coil subassembly 1012, includes a coil 1022 wound on a bobbin 1024 and a cover 1025 for securing the coil in place on the bobbin. The body subassembly 1014 includes a main body 1028, a tube 1030 and a fitting 1032. The proximal end of the tube 1030 is secured to the distal end of the main body 1028. In the illustrated embodiment, the proximal end of the tube 1030 is mounted over an annular protrusion 1035 that extends from the distal end of the main body 1028. The fitting 1032 mounts to the distal end of the tube 1030 opposite the main body 1028. In the illustrated embodiment, the fitting 1032 includes a reduced diameter portion 1046 that is sized for insertion into the distal end of the tube 1030. The main body 1028, tube 1030 and fitting 1032 can be made of stainless steel, for example, and can be secured together by suitable methods such as threaded connections, press-fitting, welding, brazing or crimping, among others.
The armature subassembly 1016 includes an armature 1050 and a pin 1051. The pin 1051 is mounted through a longitudinal passage in armature 1050. The pin 1051 may be secured to the armature 1050 by welding, brazing, press-fitting or other suitable means, for example. A first portion 1052 of the pin 1051 extends proximally from the armature 1050 and slidably engages with a longitudinal passage 1053 in the distal end of the main body 1028. A second portion 1054 of the pin 1051 extends distally in a counterbore 1055 formed in the distal portion of the armature 1050 and slidably engages into a longitudinal bore 1059 in the proximal end of the fitting 1032. As discussed above, the armature 50 in the injector 10 includes flow passages that are defined by flat portions 64 on the periphery of the armature 50. Since the injector 1010 does not include an internal cooling path for the injectable fluid, for example, diesel fuel, flow passages are not provided in the armature 1050. Accordingly, the armature 1050 may, for example, have a circular cross-section.
The valve subassembly 1020 can have similar construction and operation as the valve assembly 20 described above. In this regard, the valve subassembly 1020 includes a plunger 1070, an adapter 1072, a valve body 1074, a spring 1076 and a spring retainer 1078. The injector 1010 includes an inlet port 1138 for supplying a fluid, e.g., diesel fuel, to the injector from an external source (not shown). The fluid flows through the inlet port 1138 and into a main chamber 1139 formed between main body 1028 and the valve subassembly 1020. Fluid from the main chamber 1139 flows through a plurality of flow passages (not shown) in the valve body 1074 and into a discharge passage (not shown). The flow passages in the valve body 1074 and the discharge passage can have the same general construction as the flow passages 144 and discharge passage 146 that were described above in connection with the injector 10. In some embodiments, the flow passages can be axially offset, as described above, to create a swirling flow of fluid within the discharge passage 1146.
When the coil 1022 is deenergized, the injector 1010 is biased to its closed position by the spring 1076. The injector 1010 is moved to its open position by energizing the coil 1022. When the coil 1022 is energized, the flux path created by the coil 1022 acts on the armature 1050 to move the armature proximally (e.g., to the left in FIG. 13) within the tube 1030. As the armature moves proximally, the pin 1051 pushes against the plunger 1070 (and against the force of the spring 1076) to unseat valve head 1092 from valve seat 1094. When the valve head 1092 unseats from the valve seat 1094, fluid flows from the discharge passage 1146, through an annular flow passage 1160, out through the gap between the valve head 1092 and the valve seat 1094, and into the exhaust stream. The annular flow passage 1160 can have the same general construction and operation as the annular flow passage 160 described above in connection with the injector 10.
When the injector 1010 is connected to an exhaust component, components on the proximal end, including the valve head 1092 and valve seat 1094, will typically be exposed directly to the exhaust gases flowing through the exhaust component. As noted above, the injector 1010 includes a cooling flange 1300 that circulates cooling fluid around the injector components that are adjacent or near the flow of exhaust gas in order to cool these components. The cooling flange 1300 includes a longitudinal passage 1310 configured to receive the proximal portion of the main body 1028. In the illustrated embodiment, the main body 1028 and longitudinal passage 1310 include reciprocal threads 1312 for securing the injector 1010 to the cooling flange 1300. Alternatively, the main body 1028 can be secured to the cooling flange 1300 by welding, brazing, crimping, press-fitting or other suitable means. The cooling flange 1300 also includes an annular counterbore 1313 formed in its proximal face outwardly from and concentrically with the longitudinal passage 1310. An end cap 1314 is mounted on proximal end of the cooling flange 1300 to seal off the counterbore 1313 and define a cooling chamber 1316. The end cap 1314 can be secured in place by suitable means such as brazing, crimping, welding, press-fitting or threaded connection. The flange 1300 includes an inlet port 1320 and outlet port 1322 that are fluidly connected to the cooling chamber through longitudinal flow passages 1323 formed in the cooling flange 1300. The inlet and outlet ports can be connected to an external source (not shown) for circulating cooling fluid through the cooling chamber 1316 in order to cool the proximal end of the injector 1010.
As is shown in FIG. 14, the injector 1010 can be mounted to an exhaust component 1330 for injecting a fluid, such as diesel fuel, into an exhaust stream flowing through a passage 1332 in the exhaust component. For this purpose, the injector 1010 includes mounting features configured to mate with reciprocal mounting features on the exhaust component 1330. According to at least one embodiment, the mounting features include mounting apertures 1334 on the injector 1010 that align with reciprocal apertures 1336 on the exhaust component. Fasteners, such as bolts 1338, extend through the apertures 1134 in the injector 1010 and thread into the apertures 1136 in the exhaust component 1330 to secure the injector to the exhaust component. Spacers 1342 can be positioned on the fasteners 1338 before the fasteners are installed. The spacers 1342 can help dissipate from the injector. A gasket 1340 can be interposed between the injector 1010 and the exhaust component 1330 to seal against gas leaks.
FIGS. 15A and 15B illustrate another water-cooled injector 1010B according to at least one embodiment of the present technology. The injector 1010B includes many components that are the same or similar to those used in the injector 1010 of FIG. 13. Accordingly, like reference numerals are used to identify like components and only the primary differences between the injectors 1010 and 1010B will be described. One difference the cooling flange and main body of the injector 1010B are integrally formed with one another. This composite structure is identified with reference number 1350 in FIG. 11B.
In addition, the injector 1010B has a different path for fluid flow through the injector. In this regard, the fluid inlet 1138B is formed in the distal end of the fitting 1032B. Fluid from the inlet 1138B flows into a longitudinal passage 1354 in the fitting. Fluid then flows into the tube 1030 and through a longitudinal passage 1354 in the armature 1050B. A pin 1052B extends from the proximal end of the armature 1050 and engages against the distal end of the plunger 1070. The pin 1052B includes a longitudinal passage 1354 that is in fluid communication with the longitudinal passage 1354 of the armature 1350. Outlets 1358 in the proximal end of the passage open into the main chamber 1039B. Fluid from the main chamber 1139B flows through a plurality of flow passages (not shown) in the valve body 1074 and into a discharge passage (not shown). The flow passages in the valve body 1074 and the discharge passage can have the same general construction as the flow passages 144 and discharge passage 146 that were described above in connection with the injector 10. In some embodiments, the flow passages can be axially offset, as described above, to create a swirling flow of fluid within the discharge passage 1146.
The injector 1010 is moved to its open position (see FIG. 15B) by energizing the coil 1022. When the coil 1022 is energized, the flux path created by the coil 1022 acts on the armature 1050 to move the armature proximally (e.g., to the left in FIG. 15B) within the tube 1030. As the armature moves proximally, the pin 1050B pushes against the plunger 1070 (and against the force of the spring 1076) to unseat valve head 1092 from valve seat 1094. When the valve head 1092 unseats from the valve seat 1094, fluid flows from the discharge passage, through an annular flow passage, out through the gap between the valve head 1092 and the valve seat 1094, and into the exhaust stream. The annular flow passage can have the same general construction and operation as the annular flow passage 160 described above in connection with the injector 10.
FIG. 16 illustrates a hydraulic circuit 1600 that can be used to supply fluid to an injector 1602 according to certain embodiments of the present technology. The hydraulic circuit 1600 can include a fluid supply 1604 that delivers pressurized fluid to the inlet of the injector 1602 through a control manifold 1606. The fluid supply 1602 can include a tank 1610 and a pump 1612. The inlet of the pump 1612 can be fluidly connected to the tank 1610 through a filter 1618. The control manifold 1606 can include control valve 1614 that is moveable between open and closed positions. According to at least some embodiments the control valve can be a solenoid-operated valve. The inlet of the control valve 1614 can be fluidly connected to the pump 1612 through the filter 1618, while the outlet of the control valve can be connected to the inlet port of the injector 1602. The control valve 1614 is normally biased closed for fail-safe conditions. During operation of the hydraulic circuit 1600, the control valve 1614 can be maintained in its open position, e.g., by the solenoid, to allow pressurized fluid to be supplied from the pump to the injector. An electronic controller (not shown) can be used to selectively energize the injector 1602 to inject fluid into an exhaust gas stream, for example. When the injector 1602 includes a cooling flow path such as described in connection with the injector 10 of FIG. 1, the hydraulic circuit 1600 can include a return flow line 1622 from the injector 1602 and the tank 1610. Accordingly, when the injector 1602 is closed, fluid can be pumped from the tank 1610 through the injector 1602 and back to the tank through the return line to cool the injector in the manner described above. The return flow line 1622 can include a pressure relief valve to maintain the pressure at the injector 1602 above a minimum threshold pressure when the control valve 1614 is closed.
The control manifold 1606 can include a pressure sensor 1620 for monitoring the fluid pressure between the control valve 1614 and the injector 1602. According to some embodiments, the pressure sensor 1620 can be used to control dosing from the fluid injector. For example, look-up table can be developed to correlate inlet pressure to dosing rates, e.g., fluid flow rates, from the injector. Based on the pressure reading from the sensor, an electronic control unit can determine the flow rate from the injector and can in turn be used to control the operation of the fluid injector.
The pressure sensor can also be used for on board diagnostics, including, for example, detecting leaks in the hydraulic circuit and failure of the control valve. For example, when the control valve is commanded to be open, an absence of pressure can indicate failure of the control valve. A fluid leak can be detected by activating the pump 1612, and thereafter closing the control valve 1614 while monitoring the pressure sensor detected by the pressure sensor. A decreasing pressure reading under these conditions can indicate a fluid leak between the control valve 1614 and the injector 1602.
While this disclosure has been described as having exemplary embodiments, this application is intended to cover any variations, uses, or adaptations using the general principles set forth herein. It is envisioned that those skilled in the art may devise various modifications and equivalents without departing from the spirit and scope of the disclosure as recited in the following claims. Further, this application is intended to cover such departures from the present disclosure as come within the known or customary practice within the art to which it pertains. While this disclosure has been described as having exemplary embodiments, this application is intended to cover any variations, uses, or adaptations using the general principles set forth herein. It is envisioned that those skilled in the art may devise various modifications and equivalents without departing from the spirit and scope of the disclosure as recited in the following claims. Further, this application is intended to cover such departures from the present disclosure as come within the known or customary practice within the art to which it pertains.

Claims

1. An injector for controllably injecting a fluid into an exhaust stream, the injector comprising:

a housing defining a chamber for storing the fluid;

an orifice comprising an annular flow passage in fluid communication with the chamber; and

a valve member for controlling the flow of fluid from the chamber, through the orifice and into the exhaust stream.

2. The injector of claim 1, wherein the annular flow chamber is interposed between the chamber and the valve member.

3. The injector of claim 2, wherein the valve member comprises a valve head and valve seat formed in an outer surface of the injector that faces the exhaust stream and a valve head, the valve head being movable between closed position at which the valve head engages the valve seat and blocks fluid flow through annular orifice the and an open position at which the valve head is spaced away from the valve seat in the direction of the exhaust stream to permit fluid flow through the annular flow passage.

4. The injector of claim 3, wherein valve member seals the orifice from exhaust gas flow when the valve member is in its closed position.

5. The injector of claim 3, wherein the valve member further comprises a plunger for moving the valve head between its open and closed positions.