Fluid injector with heating device for cleaning

Abstract

Fluid injector (46) for use in an exhaust gas treatment system (14), with an injector body (98) in which a bore (109) is formed, a cooled needle element (100) received in the bore (109) by screwing, wherein a channel for conveying fuel is formed between an inner surface of the bore (109) and an outer surface of the cooled needle element (100), a heated needle element (104) arranged in the injector body (98) in fluid communication with the cooled needle element (100), wherein the heated needle element (104) has a fluid receiving end facing the cooled needle element (100) and a fluid injection end and a separation (135) is maintained between the cooled needle element (100) and the heated needle element (104), and a heating device (106) arranged around the fluid injection end of the heated needle element (104).

Description

Technical field

[0001] The present disclosure relates to a fluid injector and in particular to a fluid injector with a heating device for cleaning. background

[0002] Engines such as diesel engines, gasoline engines, gaseous fuel engines, and other engines known in the prior art emit a complex mixture of air pollutants. These air pollutants contain solids known as particles or soot. Due to increased environmental awareness, exhaust emission regulations have become stricter, and the amount of particles emitted by an engine is prescribed depending on the engine type, size, and / or class.

[0003] One method used by engine manufacturers to comply with regulations concerning particulate emissions is to remove particles from an engine's exhaust stream using a device known as a particulate trap or diesel particulate filter. A particulate trap is a filter designed to capture particles and typically consists of a wire mesh or a ceramic honeycomb medium. However, prolonged use of the particulate trap can cause particles to accumulate in the medium, reducing the filter's effectiveness and, consequently, engine performance.

[0004] The accumulated particles can be removed from the filter through a process called regeneration. To initiate filter regeneration, the temperature of the particles trapped in the filter must be raised to a combustion threshold at which the particles are burned off. One way to raise the particle temperature is to inject a catalyst, such as diesel fuel, into the engine's exhaust stream and ignite the injected fuel.

[0005] After the regeneration process, the fuel supply is interrupted. However, some fuel may remain in the fuel injector or the fuel lines that supply it. This residual fuel, when exposed to the harsh conditions of the exhaust stream, can coke or partially combust, leaving solid residues that can restrict or even block the fuel injector. Additionally, particles from the exhaust stream may enter the injector and cause blockage. For this reason, it may be necessary to regularly clean the injector of fuel and / or accumulated residues or particles between regeneration cycles.

[0006] A method for cleaning a fuel injector is described in U.S. Patent 4,987,738 (Patent '738), granted to Lopez-Crevillen et al. on January 29, 1991. More specifically, Patent '738 discloses a particulate filter with a burner used to combust trapped particles. The burner includes a fuel injector nozzle for injecting fuel into the burner during regeneration. As described in Fig. As shown in Figure 1 of patent 738, a fuel pump supplies fuel to the injector nozzle via a passage axially aligned with a bore of the nozzle. To maintain efficient and reliable burner operation, cleaning air is supplied through the axially aligned passage to the fuel injector nozzle to clean it of fuel after a regeneration process. The cleaning air flows through the injector nozzle until the next regeneration process takes place.

[0007] Although the burner of patent 738 may benefit to some extent from the cleaning process described above, the gain may be comparatively costly. In particular, the additional passes required to assist with air cleaning may increase machining costs, component costs, and assembly time. Furthermore, maintaining a continuous flow of cleaning air may be costly, and the risk of foreign matter contaminating the fluid injector nozzle may increase.

[0008] DE 198 55 385 A1 discloses a device for post-treatment of exhaust gases from an internal combustion engine, comprising a nozzle for metering and vaporizing a reducing agent, to which a heating element is assigned. US 4,870,943 A discloses a pump for use as a fuel injector. WO 2005 / 070175 A2 discloses a device for emission reduction. EP 1 624 182 A1 and US 2001 / 0052553 A1 disclose further fuel injectors.

[0009] The fluid injector of the present disclosure solves one or more of the problems discussed above. Summary

[0010] One aspect of the present disclosure relates to a fluid injector for use with an exhaust gas treatment system according to claim 1.

[0011] Another aspect of the present disclosure relates to an exhaust gas treatment system according to claim 6. Brief description of the drawings Fig. Figure 1 is a schematic and illustrative representation of an exemplary disclosed power generation unit, Fig. Figure 2 is an exploded view of an exemplary exhaust gas treatment device for use with the power generation unit of Fig. 1, Fig. Figure 3 is a cross-sectional view of the exhaust gas treatment device of Fig. 2, Fig. Figure 4 is a cross-sectional view of a fluid injector for use with the device of the Fig. 2 and Fig. 3, Fig. Figure 5 is a schematic and illustrative representation of an exemplary disclosed control system for use with the device of the Fig. 2 and Fig. 3, and Fig. 6 is a flowchart showing an exemplary procedure implemented by the control system of Fig. 5 for cleaning the fluid injector of the Fig. 4 is carried out. Detailed description

[0012] Fig. Figure 1 represents a power generation unit 10 with a fuel supply 12 and an additional regeneration system 14. For the purposes of disclosure, the power generation unit 10 is shown and described as a four-stroke diesel engine. However, it is obvious to those skilled in the art that the power generation unit 10 can be any other type of internal combustion engine, for example, a gasoline engine or an engine powered by a gaseous fuel. The power generation unit 10 can include an engine block 16 that at least partially encloses a plurality of combustion chambers 17. In the embodiment shown, the power generation unit 10 includes four combustion chambers 17. However, the power generation unit 10 can include a larger or smaller number of combustion chambers 17, and the combustion chambers 17 can be arranged in a series, V, or other suitable arrangement.

[0013] What's next in Fig. As shown in Figure 1, the power generation unit 10 can include a crankshaft 18 rotatably mounted within the engine block 16. A connecting rod (not shown) can connect a plurality of pistons (not shown) to the crankshaft 18, such that a displacement movement of each piston in its respective combustion chamber 17 results in a rotation of the crankshaft 18. Similarly, a rotation of the crankshaft 18 can result in a displacement movement of the pistons.

[0014] The fuel supply 12 can include components that cooperate to deliver pressurized fuel injections into each of the combustion chambers 17. More specifically, the fuel supply 12 can be a common-rail system and include a tank 20 designed to receive a fuel supply and a fuel pump assembly 22 designed to pressurize the fuel and deliver the pressurized fuel to a plurality of fuel injectors 23 via a rail 24.

[0015] The fuel pump assembly 22 can include one or more pump devices that serve to increase the fuel pressure and deliver one or more pressurized fuel flows to the rail 24. In one example, the fuel pump assembly 22 includes a low-pressure source 26 and a high-pressure source 28 arranged in series and fluidically connected via a fuel line 30. The low-pressure source 26 can be configured as a transfer pump that provides a low-pressure supply to the high-pressure source 28. The high-pressure source 28 can receive the low-pressure supply and increase the fuel pressure, in some cases up to 300 MPa. The high-pressure source 28 can be connected to the rail 24 by means of a fuel line 32.One or more filter elements 34, such as a primary filter and a secondary filter, can be arranged in the fuel line 32 to remove foreign matter and / or water from the fuel pressurized by the fuel pump arrangement 22.

[0016] One or both of the low- and high-pressure sources 26, 28 can be operationally connected to the power generation unit 10 and driven by the crankshaft 18. The low- and / or high-pressure sources 26, 28 can be connected to the crankshaft 18 in any manner obvious to a person skilled in the art, wherein a rotation of the crankshaft 18 results in a corresponding drive rotation of a pump shaft. For example, a pump drive shaft 36 of the high-pressure source 28 is in Fig. 1 is shown as being connected to the crankshaft 18 via a transmission linkage 38. However, it is also possible that one or both of the low- and high-pressure sources 26, 28 are alternatively driven electrically, hydraulically, pneumatically, or in any other suitable manner. Furthermore, the fuel supply 12 can alternatively be configured as a different type of fuel supply, such as a fuel injector system with a mechanical unit or a fuel injector system with a hydraulic unit, wherein the pressure of the injected fuel is generated or increased in individual injectors without the use of a high-pressure source.

[0017] The supplementary regeneration system 14 can be associated with an exhaust gas treatment device 40. In particular, exhaust gas from the power generation unit 10 can be routed via the exhaust gas passage 35 to a (not shown) end section of the exhaust gas passage 35, where the exhaust gas can be released into the atmosphere. Before reaching the end section of the exhaust gas passage 35, the exhaust gas can pass through the exhaust gas treatment device 40. In the exhaust gas treatment device 40, exhaust gas components such as particles, NOx, HC, and other components can be removed from the exhaust gas stream or otherwise converted into harmless gases. In one example, the exhaust gas treatment device 40 can include a wire mesh or a ceramic honeycomb filter medium 42, which are arranged to remove particles from the exhaust gas stream.Over time, particles can accumulate in the filter medium 42 and, if left unchecked, this accumulation can become significant enough to restrict or even block the flow of exhaust gas through the treatment device 40, thereby increasing the back pressure in the power generation unit 10. An increase in the back pressure of the power generation unit 10 could reduce its ability to draw in fresh air, leading to lower power output, increased exhaust gas temperatures, and poor fuel economy.

[0018] As in Fig. As shown in Figure 2, the supplementary regeneration system 14 can include components that work together to regularly reduce the accumulation of particles in the exhaust gas treatment device 40. These components can include, among others, a housing 44, an injector 46, a mixing plate 48, a spark plug 50, a thermocouple 52, and a combustion chamber 54. The supplementary regeneration system 14 can also include additional or different components such as one or more pilot injectors, additional main injectors, a control unit, a pressure sensor, a flow sensor, a flow blocking device, and other components known in the art. Furthermore, the exhaust gas treatment device 40 can be used instead of or in addition to the filter medium 42 (see Figure 2). Fig. 1) a device for selective catalytic reduction (SCR) and an associated (not shown) injector, which is approximately identical to injector 46, for introducing a reducing agent such as urea into the exhaust gas stream upstream of the SCR device.

[0019] The housing 44 can accommodate the injector 46, the mixing plate 48, the spark plug 50, and the thermocouple 52 and connect them fluidically. In particular, the housing 44 can have a central stepped bore 56, an annular recessed opening 58, a centrally located bore 60, a first radially offset bore 61, and a second radially offset bore (not shown). The housing 44 can further include a pilot fuel channel 62, a main fuel channel 64, an air supply channel 66, and an inlet and outlet cooling channel 68 and 70, respectively. One or more check valves (not shown) can be arranged in any or all of these channels, if desired, to ensure that the respective fluids flow in the channels in one direction and / or to reduce or minimize their volumes, which might necessitate regular replenishment or cleaning.

[0020] The centrally arranged bore 60 can allow the injector 46 to pass through an inner surface 72 (see the in Fig. 2 as the surface of the housing 44 shown opening towards the combustion chamber 54). The centrally arranged bore 60, together with the injector 46, can accommodate a pilot fuel chamber 74 in the stages of the bore 60 (see Fig. 3) form a main fuel chamber 76 and a coolant chamber 78. The pilot fuel chamber 74 can be in fluid communication with the pilot fuel channel 62, while the main fuel chamber 76 can be in fluid communication with the main fuel channel 64. The coolant chamber 78 can be in fluid communication with both the inlet and outlet coolant channels 68, 70. The mixing plate 48 can hold the injector 46 in the centrally arranged bore 60 by means of a spring component such as a Bellville disc 80.

[0021] The central stepped bore 56 can also accommodate the mixing plate 48 through its inner surface 72. The mixing plate 48 can be fully press-fitted into the central stepped bore 56 and / or held in place by a snap ring 82. The mixing plate 48 can be centrally aligned with the injector 46 and the housing 44 and angularly oriented with respect to the housing 44 by means of one or more dowel pins 83.

[0022] The first radially offset bore 61 can receive the spark plug 50 through an outer surface of the housing 44. In particular, the spark plug 50 can have an external thread that engages an internal thread of the first radially offset bore 61. The first radially offset bore 61 can, if desired, be connected to the air supply channel 66, such that carbon and other contaminants can be regularly removed from the first radially offset bore 61 and thereby prevented from accumulating on the spark plug 50 and causing undesirable arcing.

[0023] The second radially offset bore can accommodate the thermocouple 52 through the outer surface of the housing 44. Similar to the spark plug 50, the thermocouple 52 can also have an external thread that engages an internal thread of the second radially arranged bore. Although no channels are shown that bring fluids into contact with the thermocouple 52, alternatively or additionally, a cleaning fluid such as air from the supply channel 66 can be directed to the second radially offset bore to reduce or minimize the accumulation of contaminants, if desired.

[0024] The injector 46 can be arranged in the housing 44 and be operational for injecting one or more quantities of pressurized fuel (e.g., by pilot, main, and / or post-injections) into the combustion chamber 54 at predetermined times, fuel pressures, or fuel flow rates. The timing of the fuel injection into the combustion chamber 54 can be synchronized with a sensor input received from the thermocouple 52, one or more (not shown) pressure sensors, a (not shown) timer, or any similar sensor device, such that the fuel injections are essentially controlled by an accumulation of particles in the filter medium 42 (see Fig. 1) correspond. For example, fuel can be injected if the temperature of the exhaust gas flowing through the exhaust gas treatment device 40 exceeds a predetermined value. Alternatively or additionally, fuel can be injected if the pressure of the exhaust gas flowing through the exhaust gas treatment device 40 exceeds a predetermined pressure level or if the pressure drop across the filter medium 42 exceeds a predetermined differential value. Fuel can also be injected on a set regular basis, in addition to or independently of pressure and temperature conditions, if desired.

[0025] The mixing plate 48 (e.g. a swirl plate) can, together with the annular recessed opening 58 of the housing 44, form an air distribution channel 84 (see Fig. 3) form a mixing plate 48 to which compressed air can be supplied via the supply channel 66. The mixing plate 48 can contain a plurality of ring-shaped air outlets 86 that fluidly connect the air distribution channel 84 to the combustion chamber 54. The air outlets 86 can mix air with fuel injections in the combustion chamber 54 to improve combustion. Additionally or alternatively, the air outlets 86 can direct pressurized air directly to the outer periphery of the combustion chamber 54 for cooling and / or insulating purposes, if desired.

[0026] The mixing plate 48 can have openings for receiving the thermocouple 52 and the spark plug 50. More precisely, the thermocouple 52 can extend into the combustion chamber 54 via a first through-hole 88 in the mixing plate 48, while the spark plug 50 can extend into the combustion chamber 54 via a second through-hole 90. A grounded electrode 92 can extend from the mixing plate 48 near the second through-hole 90 to interact with the spark plug 50.

[0027] The spark plug 50 can ignite the fuel sprayed by the injector 46 into the combustion chamber 54. More precisely, during a regeneration process or when a catalyst in the exhaust aftertreatment device 40 requires an increased temperature, the temperature of the exhaust gas exiting the power generation unit 10 may be too low to cause auto-ignition of the fuel sprayed from the injector 46. To initiate the combustion of the fuel and consequently the trapped particles, a small amount (i.e., a pilot shot) of fuel can be sprayed or otherwise injected from the injector 46 towards the spark plug 50 to create a locally rich atmosphere that can be readily ignited by the spark plug 50.A spark formed between an electrode of the spark plug 50 and the grounded electrode 92 of the mixing plate 48 can ignite the locally rich atmosphere and generate a flame that can shoot out towards the trapped particles or propagate otherwise. The flame jet propagating from the injector 46 can raise the temperature in the exhaust aftertreatment device 40 to a level that readily supports efficient ignition of a larger quantity (i.e., a main shot) of fuel from the injector 46. If the main injection of fuel ignites, the temperature in the exhaust aftertreatment device can further rise to a level that causes the combustion of the particles trapped in the filter medium 42 and / or to a level that supports efficient operation of a catalyst.

[0028] The thermocouple 52 can confirm successful ignition of the fuel / air mixture in the combustion chamber 54 and help control the amount of fuel injected based on a given temperature. A thermocouple generally contains two different metals, often designed as slender components such as wires or rods. The two metals of the thermocouple may be joined at one measuring end of the thermocouple (usually the terminal end) via a soldered connection. When the temperature at the measuring end of the thermocouple changes relative to the temperature at a reference end (i.e., a non-measuring end), a measurable voltage can be generated. The value of the measured voltage can be used to determine a temperature at the measuring end of the thermocouple. The thermocouple 52 may extend through the mixing plate 48 into the combustion chamber 54 to indicate the temperature therein.If a temperature measured in the combustion chamber 54 exceeds a predetermined value, it can be concluded that the ignition of the air / fuel mixture was successful. Similarly, if the temperature measured in the combustion chamber 54 falls below the predetermined value, it can be concluded that the flame jet has gone out. Responding to the value of the current generated by the thermocouple 52, the fuel injections into the combustion chamber 54, the flow rate or pressure of the air supplied to the combustion chamber 54, the temperature of the injector, and / or other temperature-dependent processes can be varied.

[0029] The combustion chamber 54 (see Fig. 2) can be designed as a tubular component configured to direct an ignited fuel / air mixture (i.e., the flame jet) from the additional regeneration system 14 axially into the exhaust gas stream of the treatment device 40. In particular, the combustion chamber 54 can include a central opening 94 that brings fuel from the injector 46 and air from the distribution channel 84 into fluid communication with the exhaust gas (i.e., the central opening 94 can be in fluid communication with or extend into the passage 35). The combustion chamber 54 can employ a flame stabilizing plate 96 to provide a constraint that reduces or minimizes pulsations in the exhaust gas treatment device 40. That is, the inner diameter of the flame stabilizing plate 96 can be smaller than the inner diameter of the central opening 94.The combustion chamber 54 can generally be straight and have a predetermined length, which is set during manufacturing according to a desired flame induction position (the distance that a flame resulting from the ignition of the fuel / air mixture extends from the combustion chamber 54 in the exhaust stream). In one example, this desired induction position may be approximately 12 inches from the flame stabilizing plate 96 of the combustion chamber 54.

[0030] As in Fig. As shown in Figure 4, the injector 46 can be a structure consisting of several components designed to ensure continuous fuel injection into the combustion chamber 54 (see Figure 4). Fig. 2) interact, even under harsh operating conditions. More precisely, the injector 46 can comprise an injector body 98, a cooled needle element 100 arranged in the injector body 98, a sleeve 102, a selectively heated needle element 104 arranged in the sleeve 102, a heating device 106 which is press-fitted or otherwise coupled to the sleeve 102, and a heat shield 108 arranged around the heating device 106. Pressurized fuel can be directed for injection into and around the cooled needle element 100 towards the heated needle element 104, while a coolant can be directed around the injector body 98 to prevent coking of fuel in the cooled needle element 100. Between injection processes, any remaining fuel or accumulation in the heated needle element 104 (i.e.,Cleaning a fluid injection end of the injector 46) involves selectively applying current to the heating device 106. The outer surfaces of the injector 46 can also be cleaned of deposits and fuel, thereby maintaining a consistent spray angle and spray quality. The heat shield 108 can reduce or minimize the amount of heat convected and / or radiated by the heating device 106 during the cleaning process.

[0031] The injector body 98 can be a general cylindrical component designed for installation in the centrally arranged bore 60 (see Fig. 2) is designed and can contain one or more channels. More precisely, the injector body 98 can contain a bore 109 designed to receive the cooled needle element 100 by screwing it in, and a connected bore 110 designed to receive one end of the sleeve 102 by screwing it in. The injector body 98 can have outer surfaces with an increased diameter at opposite ends, such that a recess 112 is created between them. The recess 112 can at least partially form a coolant chamber (see Fig. 3) limit. That is, a coolant from the inlet cooling channel 68 can be in direct contact with the outer annular surface of the injector body 98 at the recess 112. One or more sealing elements 114 can be assigned to the enlarged area of ​​the injector body 98 to reduce or minimize fluid leakage and contamination between the injector body 98 and the housing 44. A flange 116 can help to correctly position the injector body 98 in the centrally located bore 60.

[0032] The cooled needle element 100 can be an elongated cylindrical component that is slidably arranged in the centrally arranged bore 60 (see Fig. 3), and is brought into engagement with the injector body 98 by screwing it together. The engagement position of the cooled needle element 100 with the injector body 98 can be essentially determined by the axial position of the recess 112 and the coolant chamber 78 (see Fig. 3) correspond. In this way, heat generated in or transferred to the cooled needle element 100 can be dissipated by the interaction with the coolant in the chamber 78 (see Fig. 3) are directed. The cooled needle element 100 can contain an inner channel 118 which connects to an inner cone 120 at the pilot fuel chamber 74 (see Fig. 3) begins and ends at a receiving end of the heated needle element 104. The cooled needle element 100 can further have an outer surface with an enlarged diameter at a fuel receiving end, such that a recess 122 is created between the enlarged surfaces of the cooled needle element 100 and the injector body 108. The recess 122 can at least partially delimit a main fuel chamber 76, while the space inside the centrally arranged bore 60, which is located at an axial upstream position of the enlarged diameter of the cooled needle element 100, can at least partially delimit the pilot fuel chamber 74 (see Fig. 3) Similar to the injector body 98, one or more sealing elements 114 can be assigned to the enlarged area of ​​the cooled needle element 100 to reduce or minimize fluid leakage and contamination between the cooled needle element 100 and the housing 44.

[0033] The sleeve 102 can be designed as a generally tubular component that firmly connects the heated needle element 104 to the heating device 106, the injector body 98, and the cooled needle element 100. That is, the sleeve 102 can have a central bore 124, which engages the heated needle element 104 screwwise, and an outer annular surface over which the heating device 106 can be press-fitted, wire-wound, brazed, cast, tightly fitted, or clamped. The sleeve 102 can also engage the connected bore 110 of the injector body 98 by screwing it in. The engagement between the sleeve 102, the heated needle element 104, and the heating device 106 can enable conductive heat transfer from the heating device 106 to the heated needle element 104. The sleeve 102 may further include a flanged section 128 located at an opposite end of the sleeve 102.The flange section 128 can axially support and position the heating device 106. A central opening 130 in the flange section 128 allows fuel injection through the sleeve 102. The Bellville disc 80 can, as previously described, be used to hold the injector 46 in the housing 44 (see figure). Fig. 2 and Fig. 3) are pressed against the flange section 128 by the mixing plate 48.

[0034] A tip 132 can be located in the central opening 130 to serve as a sealing surface. That is, an inner surface of the tip 132 can be precision-machined to form a seal against an outer surface of a second tip 134, which is positioned in the heated needle segment 104. The tip 134 can include a pilot injection port 131 and a main injection port 133. The tip 134 can also include additional ports. When the tip 134 rests on the tip 132, fuel flow around the tip 134 can be prevented, except through (not shown) precision slots that allow fuel to flow and be injected between the tips 132 and 134. Instead, if properly arranged, the fuel can be forced to flow through the injection ports of the tip 134.By providing the inner sealing surface at the tip 132 and not on the inner surface of the sleeve 102 at the central opening 130, the manufacturing of the sleeve 102 can be simplified.

[0035] The heated needle element 104 can be designed as a generally cylindrical component and, as previously described, can be screwed into the sleeve 102. The heated needle element can be configured to retain the thermal energy absorbed by the heating device 106 and / or to focus it into the nozzle section of the injector 46. The heated needle element 104 can receive pilot fuel from the cooled needle element 100 and deliver the pilot fuel for injection into the combustion chamber 54 (see Fig. 3) to the tip 134. A separation 135 may be maintained between the heated needle element 104 and the cooled needle element 100 to reduce or minimize heat conduction between them (i.e., only a raised section of the cooled needle element 100 with a reduced area may contact the heated needle element 104). Additionally, the section of the heated needle element 104 extending beyond an upstream end of the heat shield 108 may be prevented from contacting the sleeve 102, thus reducing or minimizing conductive heat transfer at this point. However, it should be noted that even if a separation may be maintained between the cooled and heated needle elements 100 and 104, a fluid seal may still be provided (e.g., by means of a gasket, an interference fit, or some other device).Furthermore, the cross-sectional area of ​​the sleeve 102 and / or the injector body 98 can be reduced or minimized at this point to further limit heat transfer to the cooled sections of the injector 46.

[0036] The heating device 106 can include an electrical coil element or coil winding 136 arranged in an injector body press-fitted onto the sleeve 102, and a single electrical conductor wire 138 used to conduct current to the coil winding 136. To generate current flow through the heating device 106, the housing 44, the mixing plate 48, the Bellville disc 80, and the sleeve 102 can be grounded. To minimize the probability of a short circuit between the electrical conductor wire 138 and the housing 44, the electrical conductor wire 138 can be insulated from the housing 44.The electrical conductor wire 138 can extend from the coil winding 136 in a vertical direction substantially parallel to an axial direction of the cooled and heated needle elements 100, 104, such that the effects of gravity and vibration on the electrical conductor wire 138 can be reduced or minimized. Alternatively, the electrical conductor wire 138 can extend from the coil winding 136 in a horizontal or other direction, if desired.

[0037] The heat shield 108 can assist the heating device 106 in reducing or minimizing the amount of thermal energy transferred to the air in the distribution duct (see Fig. 3) is convected and / or radiated, essentially enclosing. That is, the heat shield 108 can surround the coil winding 136 in an annular shape and be spaced from the coil winding 136 such that an insulating air gap 137 is created in the heat shield 108. The annular section 108 can include a radial projection that accommodates the connection between the coil winding 136 and the electrical conductor wire 138. By providing a projection instead of simply increasing the diameter of the heat shield 108 to accommodate the connection with the electrical conductor wire 138, the space in the housing 44 occupied by the heat shield 108 can be reduced or minimized. The heat shield 108 can be formed around the flange section 128 at one end.Additionally, a cap component can be arranged as an end cap 140 to close off the opposite upstream end of the heat shield 108, thereby preventing, reducing, or minimizing heat transfer to the injector body 98. The electrical conductor wire 138 can pass through a hole in the end cap 140.

[0038] Fig. Figure 5 represents a control system 142, which is used to regulate the cleaning operation of the injector 46. The control system 142 can include an engine speed sensor 144, a coolant sensor 146, a timer 148, and a controller 150. The controller 150 can be connected via connecting lines 152, 154, 156, 158, and 160, respectively, to the engine speed sensor 144, the coolant sensor 146, the timer 148, the electrical lead wire 138 of the heating device 106, and the thermocouple 52. The controller 150 can regulate the temperature of the heating device 106 based on an input from the engine speed sensor 144, the coolant sensor 146, the timer 148, and / or the thermocouple 52. Alternatively, the controller 159 could regulate the temperature of the heating device 106 based on an additional or different input, if desired.

[0039] The motor speed sensor 144 can detect the rotational speed of the power generation unit 10 and may, for example, be designed as a magnetic pickup sensor associated with the crankshaft 18 or the transmission train 38. To generate a signal corresponding to the rotational speed of the resulting magnetic field, the motor speed sensor 144 can be located near a magnetic element (not shown) embedded in the crankshaft 18, in an element of the transmission train 38, or in any other component directly or indirectly driven by the power generation unit 10. The speed signal can be transmitted to the controller 150 via the connecting line 152.

[0040] The coolant sensor 146 can be associated with coolant flowing through the injector 46 and / or coolant circulating through the power generation unit 10 (i.e., through the engine block 16, the heads associated with the combustion chambers 17, and other components of the power generation unit 10). The coolant sensor 146 can be a temperature-type sensor designed to generate a signal indicating the coolant in contact with it. The temperature signal can be routed to the control unit 150 via the connecting line 158.

[0041] The timer 148 can be a digital or analog device configured to display the time elapsed since a regeneration process, the time remaining until the next regeneration process, the duration of a regeneration process, the time elapsed since a cleaning process, the time remaining until the next cleaning process, the duration of a cleaning process, or any other similar time measurement. The timer 148 can generate a signal indicating the time measurement and send this signal to the controller 150 via the connecting line 156.

[0042] The controller 150 can be implemented as a single microprocessor or multiple microprocessors, incorporating a device for controlling a cleaning operation of the injector 46. Numerous commercially available microprocessors can be configured to perform the functions of the controller 150. It is evident that the controller 150 could readily be implemented as a general-purpose microprocessor of a power generation unit, capable of controlling numerous functions of the power generation unit. Various other known circuits can be associated with the controller 150, including power supply circuits, signal processing circuits, coil drive circuits, communication circuits, and other suitable circuits.

[0043] The controller 150 can contain one or more characteristic maps stored in its internal memory and can refer to these maps to determine the temperature, heating duration, and / or current associated with activating the heating device 106 for various cleaning operations. Each of these characteristic maps can contain a collection of data in the form of tables, graphs, and / or equations. For example, a desired type of cleaning process can be referenced using a 2D or 3D table, which is used to determine the resulting temperature and / or duration suitable for cleaning the injector 46.In another example, the desired temperature and / or duration and an available supply voltage can form the coordinate axes of another 2- or 3-D table, which is used to determine a current applied to the electrical lead wire 138 of the heating device 106 that results in the desired temperature. The controller 150 can compare the desired type of cleaning process and the available supply voltage with these characteristic curves to determine a desired temperature, a heating duration, and a required current waveform responding to the comparison. For the purposes of this disclosure, the combination of current levels induced in the heating device 106 and their durations, used to generate a single cleaning process, can be considered a current waveform.

[0044] The controller 150 can then transmit the predetermined or generated current waveform of the heating device 106 via the electrical conductor 138 to the heating device 106 at the appropriate time in order to achieve the desired temperature for the desired heating duration. For example, the controller 150 can regulate the operation of the heating device 106 in an open-loop routine based on the data from the previously described characteristic maps. Alternatively, if desired, the controller 150 can regulate the operation of the heating device 106 in a closed-loop routine based on the data from the characteristic maps and the input from the thermocouple 52 and / or other sources.

[0045] The controller 150 can send predetermined or generated waveforms to the heating device 106 in response to a received or detected trigger. More specifically, the controller 150 can activate the heating device 106 in response to the completion of a successful regeneration process, in response to a failed regeneration process indicating a blockage of the injector 46 (regeneration processes may include injection processes), and / or in response to a time elapsed since a previous cleaning process. For example, the elapsed time could be approximately 25 hours. Other and / or additional triggers can be used to initiate a heating process if desired.

[0046] The controller 150 can be configured to activate the heating device 106 only when certain conditions are met. These conditions may include, among others, that the rotational speed of the power generation unit 10 is above a predetermined speed threshold, that the temperature measured by the coolant sensor 146 is above a predetermined temperature threshold, that a minimum amount of time has elapsed since a regeneration process, and that a minimum amount of time remains until the next regeneration process. For example, the predetermined speed threshold could be approximately 600 rpm, or the idle speed of the power generation unit 10, such that engine operation is ensured during the cleaning process.In the same example, the predetermined temperature threshold may be approximately 65°C, such that the temperature generated by the heating device 106 may be sufficient to burn off residual fuel or other accumulated substances. To prevent the formation of deposits in unheated sections of the injector 46, it may be desirable to wait a minimum time after a regeneration process before initiating a cleaning process. In some cases, this minimum time may be approximately 3600 seconds. The time required for cleaning (i.e., the time needed to burn off the deposits in the injector 46) may range from 3600 to 14400 seconds. Thus, a cleaning process may only be permitted if sufficient time remains before an upcoming regeneration process. Other or additional conditions may also need to be met before cleaning, if desired.

[0047] Depending on the desired cleaning process, the controller 150 can activate the heating device 106 to reach different temperatures for different durations. For example, if the cleaning process immediately follows a regeneration process and only evaporation of the remaining fuel is desired, the temperature of the heating device 106 may only be raised to approximately 300°C for about 10 to 15 minutes. In contrast, if the cleaning process is a regular, standard cleaning process (i.e., approximately 25 hours have passed since the previous cleaning process), the required temperature may be higher and the heating duration longer. For example, a regular cleaning process may involve temperatures of approximately 475°C lasting about one hour. If the cleaning process is associated with a failed regeneration process (i.e.,(If an injection attempt during a regeneration process failed because injector 46 was clogged, the temperature of the cleaning process could be even higher and last for a longer period.) Furthermore, the controller 150 can continuously heat injector 46 to a moderate temperature, thus reducing or minimizing extreme temperature differences and shortening the time required to reach cleaning temperature levels. It should be noted that the temperatures and durations described above are associated with a fuel such as diesel fuel, and these temperatures and durations may change if a different fluid (e.g., biodiesel, urea, etc.) is passed through injector 46. It should also be noted that the durations described above are associated with elapsed time at the appropriate temperature, and not necessarily with the time elapsed since the start of the cleaning process.

[0048] Fig. Figure 6 presents an exemplary procedure for cleaning the injector 46. Fig. Section 6 is described in detail in the following section to better illustrate the disclosed system and its operation. Commercial applicability

[0049] The fluid injector of the present disclosure can be used in a variety of exhaust gas treatment devices, including, for example, particulate traps that require regular regeneration, catalytic converters that require a predetermined temperature for optimal operation, SCR (Selective Catalytic Reduction) devices that require the injection of nitrogen or another catalyst, and other similar devices known in the art. In fact, the disclosed injector can be used in any engine system that benefits from clog-free injector operation. The operation of the power generation unit 10 will now be explained.

[0050] Referring to Fig. Air and fuel can be drawn into the combustion chambers 17 of the power generation unit 10 for subsequent combustion. More precisely, fuel can be injected from the fuel supply 12 into the combustion chambers 17 of the power generation unit 10, where it mixes with the air and is combusted to generate mechanical output power and an exhaust stream of hot gases. The exhaust stream may contain a complex mixture of air pollutants, composed of gaseous and solid substances, and may contain particles. When this particle-laden exhaust stream is passed from the combustion chambers 17 through the exhaust treatment device 40, particles can be filtered out of the exhaust stream by the filter medium 42.Over time, particles can accumulate in the filter medium 42, and if left unchecked, this accumulation could become significant enough to restrict or even block the exhaust gas flow through the exhaust gas treatment device 40. As previously shown, restricting the exhaust gas flow from the power generation unit 10 can increase the back pressure of the power generation unit 10 and reduce its ability to draw in fresh air, resulting in reduced power output from the power generation unit 10, increased exhaust gas temperatures, and poor fuel economy.

[0051] To prevent the undesirable accumulation of particles in the exhaust gas treatment device 40, the filter medium 42 can be regenerated. Regeneration can take place regularly or based on a trigger condition such as an elapsed time of engine operation, a pressure difference measured across the filter medium 42, a temperature of the exhaust gas flowing from the power generation unit 10, or any other condition known in the art.

[0052] To initiate regeneration, injector 46 can be made to selectively deliver fuel to the exhaust aftertreatment device 40 at a desired rate (i.e., an injection event). When a pilot fuel injection is sprayed from injector 46 into the combustion chamber 54, a spark from spark plug 50 can ignite the fuel. When a main fuel injection is delivered from injector 46 to the exhaust aftertreatment device 40, the burning pilot fuel stream can ignite the main fuel stream. The ignited main fuel stream can then raise the temperature of the trapped particles in the filter medium 42 to the combustion level required to burn off the particles and thereby regenerate the filter medium 42.

[0053] Between regeneration cycles (including injection cycles), injector 46 can be selectively cleaned of fuel and any accumulated residue (i.e., heated to vaporize or burn off fuel and / or accumulated residue) to ensure its proper operation. An example of an injector cleaning process is shown in the flowchart of Fig. Figure 6 illustrates this. The cleaning process can begin when a cleaning trigger is received or detected by controller 150 (step 200). Cleaning can be triggered in a variety of different ways. For example, cleaning can be triggered when the time elapsed since a previous cleaning operation exceeds a threshold duration. In some situations, this threshold duration might be in the range of 20–60 hours, and more precisely, around 25 hours. In another example, cleaning can be triggered after the successful completion of each previously described regeneration operation. In yet another example, cleaning can be triggered if a regeneration operation has failed (i.e.,Regeneration may occur if ignition of the injected fuel cannot be confirmed, if the particle temperature has not reached its combustion threshold temperature, and / or if excessive combustion losses have occurred during a regeneration process. Alternatively, other cleaning triggers can be used if desired.

[0054] The next step after initiating the desired cleaning process may involve determining the trigger for that process (step 210). As previously described, cleaning processes can be triggered in a variety of ways. If the trigger is the successful completion of a regeneration process, the desired cleaning process may simply involve heating the injector 46 to vaporize any fuel remaining in the heated needle element 104 and the tips 132 and 134 (step 220). If heating is desired, the controller 150 can refer to the maps stored in its memory and send the appropriate waveform to the heating device 106, such that the temperature of the heating device 106 reaches approximately 300°C and is maintained for about 10-15 minutes.

[0055] However, if the trigger is a time elapsed since a previous cleaning process or an abnormal fuel pressure reduction rate in injector 46, a cleaning process requiring a higher temperature and / or heating time may be necessary (Cleaning Process 1). Before Cleaning Process 1 can be initiated, however, the controller 150 can compare the current operating conditions of the power generation unit with predetermined threshold conditions and determine whether cleaning at stage 1 (i.e., Cleaning Process 1) can be permitted (step 230). More precisely, if the time since a previous regeneration process is greater than the minimum threshold (approximately 3600 seconds) and the time until the next regeneration process is greater than that required for the currently desired cleaning process (approximately 1-4 hours), the power generation unit 10 is operational (i.e.,(The engine speed is greater than approximately 600 rpm) and the amount of heat generated by the heating device 106 will be sufficient to vaporize or burn off any residual fuel and / or residue buildup (i.e., the coolant temperature is greater than approximately 65°C), then the controller 150 can initiate the desired cleaning process (step 240). At this cleaning stage (i.e., cleaning process 1 as described in...) Fig. (as shown in Figure 6) the waveform directed by the controller 150 to the heating device 160 can result in temperatures up to about 475°C, which are maintained for a duration of about one hour.

[0056] If the trigger is a failed regeneration process, it can be concluded that injector 46 is at least partially clogged (i.e., a failed injection process has occurred). To clear injector 46, the temperature and duration of the heating device 106 can be increased further (i.e., the heating time in the system can be increased). Fig. Cleaning process 2, as shown in Figure 6, can be used). Similar to the requirements for cleaning process 1, before cleaning process 2 can be initiated, the controller 150 can compare the current operating conditions of the power generation unit with predetermined threshold conditions and determine whether cleaning process 2 is permitted (step 250). In this situation, time may not be a factor. That is, since the injector 46 may be at least partially clogged, cleaning with stage 2 (i.e., cleaning process 2) can be performed regardless of the time until a scheduled regeneration process. In some situations, this may require postponing the scheduled regeneration process (step 260) to allow sufficient time for cleaning. As long as the power generation unit 10 is operational (i.e.,(The engine speed is greater than approximately 600 rpm) and the amount of heat generated by the heating device 106 will be sufficient to evaporate or burn off any remaining fuel and / or residue (i.e., the coolant temperature is greater than approximately 65°C), the controller 150 can then initiate the desired cleaning process (step 270). At this cleaning stage (i.e., the in . Fig.In the cleaning process 2) shown in Figure 6, the waveform directed by the controller 150 to the heating device 106 can lead to temperatures exceeding 475°C for more than one hour. After a failed regeneration process, cleaning in an attempt to clear the injector 46 may be limited to a predetermined number of cycles. That is, if, for example, a regeneration process fails shortly after completion of a stage 2 cleaning process, other precautionary measures such as warning an operator of the power generation unit 10, shutting down the power generation unit 10, and other such measures may be taken, if desired.

[0057] The disclosed injector design can ensure continuous and successful regeneration processes by efficiently removing residual fuel and any accumulation thereof. More precisely, by heating a nozzle section of the injector (i.e., the section of injector 46 that sprays fuel into the combustion chamber 54), both residual liquids and any solid accumulation within it can be efficiently burned off. By removing both the liquids and the solids, the successful operation of the disclosed injector can be extended compared to a cleaning system that merely removes a large portion of the liquids. Furthermore, the different cleaning stages can efficiently clean the disclosed injector by cleaning only to the extent necessary at any given time.Furthermore, since a separate fluid cleaning system may be unnecessary, the complexity and effort of the disclosed injector and the associated cleaning system can be reduced.

[0058] It is obvious to those skilled in the art that various modifications and variations can be made to the fluid injector of the present disclosure without departing from the scope of protection of the disclosure. Other embodiments will become obvious to those skilled in the art when considering the description and use of the injector disclosed herein. For example, although the disclosed injector is shown to draw pressurized fuel from a fuel supply, the disclosed injector can alternatively draw pressurized fuel from a separate, dedicated source, if desired.Furthermore, although general examples have depicted the disclosed injector as being associated with a fuel for particulate regeneration purposes, the injector 46 can just as easily be used for injecting nitrogen, AdBlue, and / or urea in a selective catalytic reduction (SCR) device, if desired. Additionally, the disclosed heating device and control system can be combined with an air or chemical cleaning system to remove liquid fuel and / or residues more efficiently from the disclosed injector, if desired. The description and examples are to be considered merely illustrative, the true scope of the disclosure being defined by the following claims and their equivalents.

Claims

[1] Fluid injector (46) for use in an exhaust gas treatment system (14), with an injector body (98) in which a bore (109) is formed, a cooled needle element (100) received in the bore (109) by screwing, wherein a channel for conveying fuel is formed between an inner surface of the bore (109) and an outer surface of the cooled needle element (100), a heated needle element (104) arranged in the injector body (98) in fluid communication with the cooled needle element (100), wherein the heated needle element (104) has a fluid receiving end facing the cooled needle element (100) and a fluid injection end and a separation (135) is maintained between the cooled needle element (100) and the heated needle element (104), and a heating device (106) arranged around the fluid injection end of the heated needle element (104). [2] Fluid injector (46) according to claim 1, further comprising a sleeve (102) which surrounds the fluid injection end of the heated needle element (104), wherein the sleeve (102) is arranged between the heating device (106) and the heated needle element (104) and connects the heating device (106) to the injector body (98). [3] Fluid injector (46) according to claim 1, further comprising a heat shield (108) surrounding the heating device (106). [4] Fluid injector (46) according to claim 3, in which an insulating air gap (137) is maintained between the heating device (106) and the heat shield (108). [5] Fluid injector (46) according to claim 2, wherein the injector body (98), the heated needle element (104), the heating device (106) and the sleeve (102) are held in place by a mixing plate (48). [6] Exhaust gas treatment system (14) with a passage (35) designed to receive an exhaust gas, and a fluid injector (46) according to one of the preceding claims, which is configured to inject a fluid into the exhaust gas in the passage (35). [7] Exhaust gas treatment system (14) according to claim 6, wherein the fluid taken up and injected by the fluid injector (46) is diesel fuel, and the exhaust gas is produced by a diesel engine (10). [8] Exhaust gas treatment system (14) according to claim 6, wherein the heating device (106) is coupled to a fluid injection end of the fluid injector (46). [9] Exhaust gas treatment system (14) according to claim 6, in which a heat shield (108) is arranged around the heating device (106). [10] Exhaust gas treatment system (14) according to claim 6, wherein the fluid injector (46) contains a sleeve (102) coupled to the injector body (98), the cooled needle element (100) is arranged in the injector body (98) for receiving the fluid, and the heated needle element (104) is arranged in the sleeve (102) in fluid connection with the cooled needle element (100) for injecting the fluid.

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