1. Field of the Inventions
The present application relates to emission reduction devices, systems, and control methods, and more particularly to devices, systems, and control methods for reducing exhaust emissions from a diesel engine.
2. Background of the Inventions
The toxic release into the atmosphere of exhaust emissions from compression ignition (“diesel”) engines is a global environmental problem and is prevalent in populated areas world-wide. Exhaust emission reduction of gases, solids, and condensates of diesel-powered systems have been the subject of both new and retrofit devices and methods.
An internal combustion engine burns hydrocarbon fuel (approximately 85% carbon and 15% hydrogen) in oxygen from incoming air (approximately 20% molecular oxygen and 78% molecular nitrogen). For diesel engines, the combustion process burns a mass ratio of air-to-fuel generally in a range of 19 under load to more than 40 at idle. This range is lean (fuel poor) to very lean since the stoichiometric mass (chemically balanced) air-to-fuel ratio is 14.7, stoichiometric being neither fuel rich nor fuel poor.
An engine exhaust flow generally consists of CO2, water, nitrogen, oxygen, and pollutants. These pollutants can be the result of undesirable high temperature and pressure combustion of nitrogen of the engine's incoming air (e.g. NOx) and the incomplete combustion of the hydrocarbon fuel including particulate matter (PM), i.e. soot, unburnt and partial hydrocarbons (HC), and carbon monoxide (CO). NOx is a general term usually denoting nitric oxide (NO) and nitrogen dioxide (NO2). The emission control strategy for automobiles with a spark ignition engine (“gasoline engine”) generally uses an after treatment device called a three way catalytic converter (TWC) that includes a sensor (“lambda sensor”) that measures oxygen in the exhaust stream relative to ambient levels. The lambda sensor can provide a feedback to the engine fuel control system in order to maintain a stoichiometric air-fuel ratio. Lambda can refer to the actual air-fuel ratio divided by the stoichiometric air-fuel ratio. The TWC uses two catalysts for oxidizing CO and HC and a third catalyst for converting NOx to molecular nitrogen (N2). However for the three catalysts to function properly, the gasoline engine is required to run the combustion process at stoichiometric, that is, the air-fuel ratio must be neither rich nor lean in fuel (lambda equal to 1)
Diesel engine exhaust emissions species are different than gasoline engine emissions. For example, diesel engine exhaust emissions include more air (N2 and O2) and PM. Gasoline-fueled spark ignition engines generally have very little PM emissions compared to diesel engines. Diesel engines are always operated lean, and therefore can not use the same emissions control strategy as used in the automobile exhaust system, especially the NOx catalyst due to the high oxygen content of the exhaust. Some diesel emission reduction methods use a filter to trap and collect the PM (e.g. soot). The accumulated soot can build up to the point of clogging the exhaust system, ultimately resulting in damage to the engine. The filter must be either routinely replaced or cleaned (often referred to as regeneration) to burn out the soot accumulation before the system can be used again without damage to the engine.
The diesel engine emissions of PM and NOx released into the atmosphere are especially a public health problem. Current methods and devices process a subset of pollutants, and require multiple bulky devices to be installed. Devices and methods that have been explored are diesel oxidation catalyst (DOC), injection of fuel-borne catalysts, engine gas recirculation (EGR), selective catalytic reduction (SCR), as well as diesel particulate filters (DPF). DPF are commonly used to reduce PM since the efficiency of the filter is good over a range of particle sizes (10 nm to 500 nm). A DPF can be fitted to new engines as well as retrofitted to existing engines, provided that the DPF does not increase engine exhaust backpressure beyond certain limits.
Practical DPFs have a filter medium consisting of a porous material in a wall-flow structure such as a ceramic honeycomb whereby alternate cell ends are closed requiring the flow through the fine microporous walls. Other surface-rich media may be sinter filters that are formed as a bag or bellow structures. Yet other types are fiber filters and filter papers similar to inlet air filters. A consequence of DPF, however, is that the build-up of accumulated PM and ash (“soot loading”) can impact the engine as increased back-pressure. Increasing back-pressure can rob the engine of power, increasing fuel usage and ultimately damaging the engine. Additionally, the DPF can trap PM but can not provide reductions of gases of CO and NOx. To reduce CO and NOx requires more devices such as DOC to reduce CO and THC, and SCR to reduce NOx.
Only a few technologies such as EGR and SCR have attacked the NOx problem, with limited operational success. EGR feeds back cooler exhaust into the hotter combustion to reduce NOx, causing lower temperatures in the cylinders. Contamination within the engine has resulted in fewer EGR devices. SCR requires the introduction of urea or ammonia as a reductant in its chamber to chemically process the NOx. SCR requires an infrastructure to support normal operation. For diesel-powered transportation equipment SCR has a number of problems. The infrastructure to replace and maintain this in the field is enormous. In addition, another device (e.g. filter) must be included in the output, since during the reduction process some of the ammonia can “slip” out into the atmosphere.
Thermal afterburning has been used as a cogeneration process for boilers and was tried as an after treatment device to reduce hydrocarbon emissions by completing the combustion process. Emissions control of pollutants such as PM, CO and HC can be burnt to completion, producing CO2 and H2O, but as the temperature is increased to promote burning, some of the molecular nitrogen in the air is converted to NOx (e.g. NO and NO2). In the past, thermal afterburning was tried as an emission control device to increase the specific residence time at high temperatures for combusting to completion the exhaust gas constituents, but as described above, this failed to reduce NOx and therefore has had limited utility.
In engine applications, including but not limited to those of trucks, construction equipment, stationary generators, railroad locomotives, and marine vessels, exhaust emissions can consist of harmful pollutants such as nitric oxides (NOx), PM, CO, and HC. As described above, diesel engines cannot use catalytic converters to eliminate some or all of these pollutants, and current technology does not efficiently and accurately address the problems associated with emissions in such engines. In particular, current technology does provide for an efficient way to convert and/or burn PM, CO, and HC to carbon dioxide and water, while at the same time reducing nitric oxides in the exhaust. Therefore, an aspect of at least one of the embodiments disclosed here includes the realization that it would be advantageous to have a single system, capable of use with new engines or of retrofitting on old engines, including but not limited to diesel engines, which can efficiently reduce and/or eliminate the harmful pollutants described above.
Thus, in accordance with at least one embodiment, a system for reducing engine exhaust gas pollutants can comprise a tube assembly comprising an injector head, a plurality of chambers, at least one of the chambers coupled to the injector head, and the plurality of chambers further comprising at least one component for directing a flow of mixture inside the tube assembly. The tube assembly can further comprise a discharge exhaust pipe coupled to one of the chambers, a heat exchanger coupled to the plurality of chambers, and an untreated exhaust inlet coupled to the heat exchanger. The system can further comprise a fuel flow device coupled to the injector head, an air device coupled to the injector head, and a controller configured to communicate with the fuel device, the air device, and the injector head.
Thus, in accordance with at least another embodiment, a device for reducing exhaust emission pollutants through combustion processes that burn hydrocarbon fuel in the presence of air can comprise a plurality of chambers in communication with an engine exhaust source and a discharge pipe, the plurality of chambers comprising components configured to manipulate an exhaust flow inside the chambers and form timed heated chemical environments for the combustion of chemical pollutants.
Thus, in accordance with at least another embodiment, a method of reducing exhaust gas pollutants in an engine's exhaust can comprise providing an assembly comprising an injector head, a plurality of chambers, at least one of the chambers connected to the injector head, the plurality of chambers comprising at least one component for directing a mixture of flows inside the tube assembly, a discharge exhaust pipe connected to one of the chambers, a heat exchanger connected to the plurality of chambers, an untreated exhaust inlet connected to at least one of the heat exchanger and injector head, and a controller in communication with the injector head. The method can further comprise directing untreated exhaust from the engine to at least one of the injector head and heat exchanger, directing secondary fuel and secondary air into the injector head, igniting the secondary fuel, directing the ignited secondary fuel and secondary air into the plurality of chambers, directing the untreated exhaust from at least one of the injector head and heat exchanger into the plurality of chambers to form the flow of mixture inside the tube assembly, treating the untreated exhaust by combusting pollutants in the flow of mixture in the plurality of chambers, cooling the mixture of flow in the plurality of chambers to reduce nitric oxides mixture of flow, and discharging the mixture of flow out the discharge exhaust pipe.
Thus, in accordance with yet another embodiment, a basic control method for controlling secondary fuel and secondary air sources in a system which reduces engine exhaust gas pollutants can comprise providing an assembly comprising an injector head, a plurality of chambers connected to the injector head and a discharge exhaust pipe, an untreated exhaust inlet connected to the plurality of chambers, a controller in communication with the injector head, at least one ambient sensor, and at least one temperature sensor adjacent the exhaust inlet and at least one temperature sensor adjacent the discharge exhaust pipe. The method can further comprise collecting temperature, humidity, and pressure data from the at least one ambient sensor and at least one temperature sensors, comparing the obtained temperature data with predetermined values of temperature set points in the controller, and based on the set points, determining a temperature error, calculating a desired composite lambda, the composite lambda representing a total air and fuel ratio inside the plurality of chambers, separating the desired composite lambda and producing secondary fuel and secondary air commands which direct secondary fuel and secondary air into the plurality of chambers to be mixed with untreated exhaust, and monitoring the discharge temperature of the mixture at the discharge pipe and modifying the secondary fuel and secondary air commands.
Thus, in accordance with yet another embodiment, a dynamic control method for controlling secondary fuel and secondary air sources in a system which reduces engine exhaust gas pollutants can comprise providing an assembly comprising an injector head, a plurality of chambers connected to the injector head and a discharge exhaust pipe, an untreated exhaust inlet connected to the plurality of chambers, a controller in communication with the injector head, at least one ambient sensor, and at least one temperature sensor adjacent the exhaust inlet and at least one temperature sensor adjacent the discharge exhaust pipe. The method can further comprise collecting temperature, humidity, and pressure data from the at least one ambient sensor and at least one temperature sensors, comparing the obtained temperature data with a pre-loaded table of temperature set points in the controller, and based on the set points, determining a temperature error, calculating a desired composite lambda, the composite lambda representing a total fuel and air ratio inside the assembly, adjusting the rate of rise and fall for the desired composite lambda in order to minimize potential overshoot or undershoot of a desired discharge temperature at the discharge exhaust pipe, adjusting the desired composite lambda to compensate for steady-state errors, separating the desired composite lambda and producing secondary fuel and secondary air commands which direct secondary fuel and secondary air into the plurality of chambers to be mixed with untreated exhaust, and monitoring the discharge temperature and modifying the secondary fuel and secondary air commands.
These and other features and advantages of the present embodiments will become more apparent upon reading the following detailed description and with reference to the accompanying drawings of the embodiments, in which:
a is a front elevational view of an embodiment of a helical stator used in the injector head.
b is a front elevational view of an embodiment of a helical stator used in the converter tube assembly.
a is a schematic top view of an embodiment of a heat exchanger of the system of
b is a schematic side view of the heat exchanger of
With reference to
The system 10 can further include a thermal controller 20, fuel device 22, and air device 23, each of which can be in communication with and/or connected to the tube assembly 12. In some embodiments, the fuel device 22 can comprise a fuel flow rate controller. In some embodiments, the air device 23 can comprise an air blower or blowers. The system 10 described herein can be used, for example, to treat untreated exhaust gas which exits from an engine, and to reduce emissions of harmful pollutants such as particulate matter (PM) and oxides of nitrogen (NOx) in the exhaust gas.
With continued reference to
With continued reference to
Adding a burning secondary fuel and air mixture to an untreated heated exhaust inside the tube assembly 12 can facilitate completion of chemical conversion processes inside the tube assembly 12, and reduce the amount of pollutants that exit through the exhaust pipe 18. Such pollutants can include, but are not limited to, NOx by-products, unburned compounds including paraffinic, naphthenic, and aromatic hydrocarbons, partially-burned combustion products of carbon monoxide and hydrocarbons including aldehydes and keytones, and thermal decomposition products including particulate matter (i.e. elemental and organic carbon, and polycyclic hydrocarbons).
With reference to
With continued reference to
With continued reference to
With reference to
With reference to
As the swirling mixture of secondary fuel, secondary air, and/or exhaust begins to rotate due to the helical stator 38, the mixture can be ignited by the igniter 32 in injector head 14, and start to burn. In at least one embodiment, the igniter 32 can be activated by the controller 20 until a flame detector detects heat, at which point the igniter 32 can be shut off. As the mixture of secondary fuel, air, and/or exhaust begins to burn, the mixture can be directed into the chambers of assembly 16.
With continued reference to
With reference to
With continued reference to
With continued reference to
Once inside mixing chamber 56, the rotating, burning, secondary fuel, secondary air, and/or untreated exhaust mixture arriving from injector head 14 can be mixed in a turbulent fashion with the untreated exhaust entering through holes 58. The untreated exhaust can be diluted inside the mixing chamber 56, and the flow velocity and turbulence on the inside of mixing chamber 56 can thoroughly mix the constituents.
The mixing chamber's length-to-diameter ratio can be kept on the order of one so that any gas film conductance is overridden by turbulence, enhancing heat transfer to the incoming untreated exhaust. In some embodiments the mixing chamber 56 is connected to the injector head 14, and the length-to-diameter ratio of an inner tube (e.g. shell) of the mixing chamber is less than three. The mixing chamber's diameter and internal overall flow resistance can also be sized to maintain a back pressure that substantially matches the operating characteristics of the particular engine and/or application the system 10 is working on at the time.
With reference to
In some embodiments, the combustion chamber 60 can have a diameter and length compatible with the mixing chamber 56. As solids in the mixture burn in the combustion chamber 60, the releasing gases can find their way out through the helical stator's vane openings 70, and move further along in the assembly 16. Within the combustion chamber 60, the mixture of secondary fuel, secondary air, and untreated exhaust can combust at high temperatures, and a majority of the remaining chemical energy of the mixture can be released, oxidizing some compounds in the mixture, but increasing NOx formation. The helical and rotational motion of the mixture caused by the stators 38 and 62 can create a coil-like pattern as the mixture travels downstream through the combustion chamber 60.
The centrifugal effect of this turbulent mixture rotation in the combustion chamber 60 can cause the more massive constituents in the turbulent mixture to be thrown towards the chamber wall. Since the heavier particles have a translating component, the heavier particles can hit the rim dams 64 of helical stators 62. The helical stator rim dams 64 can deflect the passage of these particles in the turbulent mixture, increasing their dwell time within the combustion chamber 60. Thus, the turbulence induced by the helical stators 62 can cause a longer residence time (i.e., dwell time) in the combustion chamber 60.
As the helical coil of flow tightens the radial temperature distribution pattern can generally become more pronounced. For example, the distribution pattern can be higher at the core of the flow and lower at the combustion chamber's wall. After moving through the combustion chamber 60, the mixture can enter a reaction chamber 72. The reactions inside the reaction chamber 72 can sustain the combustion of any remaining hydrocarbon in the mixture.
With reference to
With reference to
For a given translational velocity with no frictional or turbulent losses in the tube assembly 12, there can be a preferred spacing of helical stators. For example, with a given design of helical stators (same number of vanes, equally spaced vanes, vane opening angles, and radial dimensions of rim dam and stop) the helical stators can be positioned in a constant diameter chamber at a characteristic length (preferred distance between stators) such that the stream of rotating multi-phase fluid components in the mixture maintains a rotation similar to a spinning bullet traveling down a rifled barrel. In other words, for a given tube length, the helical stators can be spaced apart in such a way that the flow rotates at a minimum up to one complete full rotation in between each helical stator.
This characteristic length can be dependent upon, for example, the mass bulk density of the mixture flowing through the given chamber, the initial flow translational velocity, and the length and number of vanes. By altering these factors, different characteristic lengths can be achieved, and the helical stators can be spaced apart so as to create preferred dwell times. For example, in at least some embodiments, the helical stators can be spaced apart such that one-half of a full rotation occurs between each stator, or some other fraction or multiple of a full rotation. This can facilitate turbulence within the chamber, decelerating the flow components and resulting in increased mixing and dwell time as compared to a chamber without any stators. In some embodiments, the dwell times for particulate matter inside a single chamber can range from 20 milliseconds to 200 milliseconds, depending on the chamber temperature and incoming exhaust volumetric flow rate. In some embodiments, the total flow of mixture inside the tube assembly 12 can be held between 50 and 1000 milliseconds. Other ranges for dwell and/or holding times are also possible.
The helical stators described herein also can affect the backpressure felt within the converter tube assembly 12. By varying the geometry (e.g. length and surface area of rim dams and stops) and positioning of the helical stators, the pressure within the tube assembly 12 can be altered or adjusted as desired.
With reference to
NOx reduction within the converter tube assembly 12 can be accomplished via cooling and catalytic conversion. Cooling can occur through the use of a device such as the heat exchanger 46. With continued reference to
With reference to
With reference to
In at least one embodiment, the heat exchanger 46 tube packets can raise the untreated exhaust temperature by 350° F. (450 K), deriving their source of heat primarily from the combustion chamber 60. Other temperature increases or ranges are also possible. The heat exchanger 46 can thus provide preheating to the incoming untreated exhaust from inlet 24 to decrease the required secondary fuel usage from fuel device 22. While the illustrated embodiment shown in
With continued reference to
In at least one embodiment, the cross-sectional shape of the heat exchanger 46 can be rectangular to make maximum use of the tube lengths. Other cross-sectional shapes can also be implemented, including a circular cross-section. As described above, the heat exchanger 46 tubes can derive their source of heat from the combustion chamber 60 flow output as the mixture of secondary fuel, secondary air, and/or exhaust discharges from the combustion chamber 60 towards the exhaust pipe 18. The flow output of the heat exchanger 46 tubes can be channeled toward the mixing chamber openings 58. This method of preheating the untreated exhaust can facilitate reduction of secondary fuel usage.
Referring to
In some embodiments, heat-resistant metal tubes can be used in the heat exchanger 46. As described above, these tubes can be coated and/or uncoated. In some embodiments, poison-resistant lean NOx catalyst coatings can be used. Coatings can be selected to reduce NOx. The catalyst coatings can, in some embodiments, preferably comprise a metal zirconium phosphate such as barium, cesium or silver. (Reference is made, for example, to U.S. Pat. No. 6,407,032 B1, issued Jun. 18, 2002 to Labarge et al., which describes a poison resistant lean NOx catalyst) Embodiments can vary according to application.
With continued reference to
The reaction chamber 72 can complete the high-temperature combustion transition phase prior to introducing the mixture into the cooler flow zone of the heat exchange 46. The gas to gas heat transfer process of the heat exchanger 46, as well as the heat exchanger's length can facilitate cooling of the flow of mixture in the tube assembly 12. As described above, by cooling the heated mixture as the mixture moves through the heat exchanger 46, some or all of the NOx components remaining in the mixture can be reduced and converted into nitrogen and oxygen before leaving through exhaust pipe 18.
In some embodiments, other cooling methods besides that shown in
In some embodiments, the chamber length of the reaction chamber 72 can be at least twice the chamber's diameter such that the heat transfer across the chamber wall is established by the combustion products on the inside of the chamber and any air coolant flow on the other side. This can facilitate cooling of the combustion products inside the reaction chamber 72 and reduction of NOx.
The tube assembly 12 and thermal converter systems described above can be used with a variety of engines and/or applications, including but not limited to diesel engines using diesel fuel or biodiesel blends. As described above, the thermal tube assembly 12 can use a series of chambers and helical stators. While the embodiment illustrated in
As described above, combined secondary air, secondary fuel, and untreated exhaust can be directed through the tube assembly 12. The chambers and helical stators inside can provide a travel path in which controlled axial and radial temperature distributions provide desirable reaction times that are mass dependent. Thus, the tube assembly 12 and system 10 described above can utilize timed heated chemical environments (e.g. mixing chamber 56, combustion chamber 60, reaction chamber 72, and heat exchanger 46) to promote selected reactions and reduce unwanted emissions. A chemical atmosphere or atmospheres can be provided inside the tube assembly 12 which cause chemical changes by inducing oxidation and/or reduction reactions, even in the presence of the engine exhuast's excess air. These chemical environments can range in temperature. In at least one embodiment, for example, the temperatures in the above-mentioned chambers can range from 800° F. (700 K) to 2300° F. (1533 K). Other ranges and temperatures are also possible, although staying below 2800° F. (1810 K) can be preferred due to the onset of rapid NO formation reactions. Chamber temperature zones can be provided for thermal mixing, high temperature combustion, heat exchanger cooling, and/or discharge cooling. In some embodiments, the tube assembly 12 can eliminate approximately 89 percent of all particulate matter.
The tube assembly 12 and system 10 described above can be used advantageously, for example, to reduce and/or eliminate nitrogen oxides (NOx, the compounds of nitric oxide NO and nitrogen dioxide NO2), particulate matter (PM, carbon “soot” that is in the solid state), unburned hydrocarbons including paraffins, olefins, and aromatic hydrocarbons, and partially-burned combustion products such as carbon monoxide (CO) and hydrocarbon substances including aldehydes, ketones, and carboxylic acids. The system 10 can, for example, be used on new engines, retrofitted onto old engines, or be used with other sources of untreated exhaust. In some embodiments, the system 10 can be retrofitted onto an existing automobile, such as a diesel engine truck.
With reference to
The controller 20 can be configured to monitor conditions of the system 10 via the sensors described above, and to maintain a predetermined discharge temperature at the exhaust pipe 18. For example, the controller 20 can estimate the remaining fuel and oxygen levels of the incoming untreated exhaust at inlet 24, as well as the fuel and oxygen levels of the tube assembly's outgoing discharge at exhaust pipe 18, and then adjust the secondary fuel (from fuel device 22) and secondary air (from air device 23) to maintain a predetermined discharge temperature or temperatures at the exhaust pipe 18. These predetermined temperature points can provide the most favorable reduction of pollutants, such as NOx, while minimizing secondary fuel and secondary air usage.
Additionally, the controller 20 can be configured to monitor conditions of the tube assembly 12, and to maintain a predetermined air/fuel mass ratio inside the tube assembly 12. By maintaining a predetermined air/fuel mass ratio, the reactions occurring in the chemical environments (i.e. chambers), as well as the resultant emission reduction, can be controlled.
With reference to
With continued reference to
The controller 20 can monitor and control the air device or devices 23, or other cooling sources. The controller 20 can communicate with the igniter 32 in injector head 14, and can monitor and control fuel device 22. The fuel device 22 can include a fuel valve, which can be turned off and on to dispense appropriate amounts of fuel based on a signal or signals from the controller 20. A maintenance and data logging interface 210 can provide a self-test function, data table uploads, and data logging downloads. In some embodiments, further auxiliary inputs and auxiliary flow controls can be used. For example, in some embodiments, the controller 20 can include a data interface which monitors and/or takes into account engine rpm and/or throttle position.
With reference to
Sequence control 212 can provide for the overall orderly startup, employment, and safe shutdown of the controller 20 and system 10. The sequence control 212 can comprise a maintenance control 218, and a power up/restart control 220. A mode initialization control 222 can determine which mode (e.g. a basic or dynamic mode) the system is to operate in when controlling the emissions level of the engine exhaust. The determination of what mode to operate in can be based, for example, upon which data tables have been uploaded into the controller 20.
The sequence control 212 can further comprise a normal operation control 224 and shutdown mode control 226. The normal operation control 224 and shutdown mode control 226 can facilitate an optimal emissions reduction for a given embodiment and provide proper ignition 32 of the fuel spray in
With continued reference to
The dynamic mode of operation 232 can respond to transient conditions which result from the system's changing load conditions. Changing load conditions normally cause a change in exhaust gas composition, including changes in pollutants. The dynamic mode of operation 232 can efficiently respond to changing fuel and air in the untreated exhaust stream entering inlet 24. This dynamic response can result in using less secondary fuel and secondary air as compared to the basic mode, thereby resulting in better fuel economy for the system 10.
With continued reference to
The combustion control 216 can comprise a fuel control 236. As described above, the controller can communicate with the fuel device 22 to control the amount and rate of secondary fuel delivery which is directed into the injector head 14.
The combustion control 216 can further comprise an AFR (air to fuel ratio) control 238. The AFR control 238 can, in combination with the fuel control 236 and air control 234, control the air to fuel ratio of the secondary air and secondary fuel directed into the injector head 14, and consequently, the tube assembly 12.
The combustion control 216 can further comprise a thermal control. As described further herein, the thermal control 240 can further control the amount of secondary fuel and secondary air entering tube assembly 12. In some embodiments, the combustion control 216 can further comprise auxiliary controls 242.
With reference to
With reference to
With reference to operation block 246, the controller 20 can then collect information about the temperature of the untreated exhaust at inlet 24 from sensor 202, as well as the temperature of the exhaust being discharged out exhaust pipe 18 from sensor 206.
When an engine is running at a given load, the incoming untreated exhaust will generally have a temperature related to the load (for example 2-cycle and 4-cycle diesel engines each generally show a linear increase in exhaust temperature as a function of percent of full load, though each have a different rate of increase). Ideally, for a given engine load, the discharge temperature should be within a certain range, indicating that hydrocarbon pollutants have been burned off, and NOx has been reduced.
Based on the temperature readings from the sensors described above, particularly that of the incoming untreated exhaust sensor, the controller 20 can get an indication of the engine load. Based on this indication and the values obtained from the other sensors, and with reference to operation block 248 in
Ktube-1*((Tdischarge−T set point one)−(Texhaust−T set point 2)), where Ktube-1 is a function of shell construction and temperature, and the temperature set points are derived from uploaded temperature tables in the controller 20.
The composition of remaining fuel in the untreated exhaust, along with secondary fuel and secondary air (introduced from fuel device 22 and air device 23) can produce a composite temperature environment inside the tube assembly 12. Based on the temperature error obtained above, and with reference to operation block 250 in
Similar to the industry of modern gasoline engines with three-way catalytic converters, lambda in general can be a desired air-fuel ratio divided by the stoichiometric air-fuel ratio for a given application. Therefore, a lambda equal to one can be an air-fuel mixture that is neither rich nor lean. Composite lambda, as described herein, can be a lambda which relates to the total air and total fuel in the tube assembly 12. Thus, it can be a composite of the secondary air, secondary fuel, and any air and fuel in the untreated exhaust. The desired composite lambda can be a value which can help ensure that the discharge temperature at exhaust pipe 18 is within a predetermined range, and that the pollutants in the untreated exhaust (including NOx) are being converted appropriately into their less harmful forms.
Based on the information it has from the sensors described above, the controller 20 can calculate a desired composite lambda that will provide a chemical environment which will complete the combustion process at a minimum temperature and maximum use of oxygen. Such an environment can be ideal in that it requires as little secondary fuel as possible, while still completing the combustion processes desired.
With continued reference to
With reference to operation block 254 of
With continued reference to
For example, and with continued reference to decision block 256 in
With reference to operation block 258, if changes are needed to the secondary fuel and/or secondary air commands, a change direction logic can calculate appropriate changes and modify the secondary fuel, F command, and secondary air command, A command. Because the controller 20 is using only two temperatures (untreated exhaust temperature and discharge temperature), but there are four variables (secondary fuel, secondary air, fuel in the untreated exhaust, air in the untreated exhaust), the logic of controller 20 can monitor a temperature runaway and adjust accordingly.
With reference to operation block 260, if no change is needed to a secondary fuel or secondary air command, then the commands can simply pass along to fuel flow device 22 and/or air device 23.
In some embodiments, the basic mode of operation 230 described above can further use oxygen sensors at the exhaust inlet 24 and discharge location 18 to estimate minimum secondary air using a method similar to the temperature error formula. In some embodiments, the basic mode of operation 230 can be used as an alternate method, for example, if another method and its required sensors fail to operate.
With reference to
With reference to operation block 264 in
With reference to operation block 266 in
Based on the temperature error obtained above, and with reference to operation block 268 in
With reference to operation block 270, in order to provide a smoother response (less overshoot or undershoot), the controller 20 can use rate feedback in the dynamic mode of operation 232. For example, the controller 20 can adjust the rate of rise and fall for the desired composite lambda, providing a control over incoming engine exhaust transients while minimizing potential overshoot or undershoot of the desired discharge temperature at exhaust pipe 18.
Over time, it is possible for a sensor in the system 10 to drift or degrade in its output, resulting in possible errant commands from the controller 20. With reference to operation block 272 in
With reference to
With reference to operation block 254 of
With continued reference to
With continued reference to decision block 256 in
With reference to operation block 258, if changes are needed to the secondary fuel and air commands, a change direction logic can calculate appropriate changes and modify the fuel, F command and air command, A command.
With reference to operation block 260, if no change is needed to a secondary fuel or air command, then the commands can simply pass along to fuel device 22 and/or air device 23. In some embodiments, the command to the fuel device 22 in the dynamic mode can result in adjustment of the fuel delivery from a full spray to intermittent dosing in the injector head 14.
As described above, the system 10 and methods of use can be incorporated with engine applications, including but not limited to those of a vehicle, truck, or other device. In some embodiments of the system 10, the system 10 can include emissions control or operational performance needs that extend sensory information beyond that of the preferred embodiment to include one or more sensors and or transducers for, but not limited to, the following: displacement of linear or angular position of one or more dimensions or terrestrial positioning (e.g., global positioning system), speed/rpm, acceleration, non-contacting magnetic, ultrasonic, vibration, volumetric or mass flow meter measurements, gas concentration measurements (other than the lambda sensor), static or dynamic force or torque measurements, and electromagnetic (such as optoelectronic) measurements. In some embodiments the system 10 can acquire system data from existing application interfaces.
Although these inventions have been disclosed in the context of certain preferred embodiments and examples, it will be understood by those skilled in the art that the present inventions extend beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the inventions and obvious modifications and equivalents thereof. In addition, while several variations of the inventions have been shown and described in detail, other modifications, which are within the scope of these inventions, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments can be made and still fall within the scope of the inventions. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed inventions. Thus, it is intended that the scope of at least some of the present inventions herein disclosed should not be limited by the particular disclosed embodiments described above.
This application claims benefit under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 61/042,665, filed Apr. 4, 2008, which is incorporated in its entirety by reference herein.
Number | Date | Country | |
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61042665 | Apr 2008 | US |