JP2007529678A - Exhaust filter regeneration process, method and apparatus - Google Patents

Abstract

  An exhaust filter regeneration process in which the filter (20) is regenerated by initiating an exothermic reaction in the filter (20) to burn out the adsorbed particulate matter will be described. To achieve the proper regeneration temperature, fuel is injected into the exhaust stream and oxidized in contact with the catalytic converter (18). The control process includes fuel injection metering that depends on the exhaust stream temperature to provide a flexible control process that is independent of the engine duty cycle.

Description

  The present invention relates to an exhaust filter regeneration process, method and apparatus for use, for example, in the exhaust flow of a diesel engine.

  Such exhaust filters are used to remove carbon monoxide, hydrocarbons and NOx contaminants and particulates produced in the exhaust system.

  In known systems, dust removal is usually most effectively achieved by the use of filters. Regenerative traps such as CRT (Continuous Regeneration Trap) are found in ceramic or silicon carbide filters, often referred to as diesel particulate filters (DPF), that collect dust particles in the porous walls of the filter honeycomb structure. It works according to the principle of retaining dust particles. Such accumulation of soot within the filter surface increases the back pressure of the filter, thus necessitating regeneration of the filter.

  Regeneration is achieved when the exhaust temperature reaches about 600 ° C, at which temperature, the components of the exhaust gas stream react with soot and cause an exothermic reaction. The exothermic reaction oxidizes soot and burns out. As a result, the trap temperature increases. In the presence of a catalyst, regeneration occurs at a lower temperature.

  Exhaust gas and filter temperatures are critical to the regeneration process and cause various problems with the technology. For example, there are engine duty cycles that cannot achieve exhaust gas temperatures that allow for self-regeneration.

It is known to reduce the regeneration temperature by introducing a catalyst component that reacts with the exhaust gas upstream of the filter to generate an atmosphere with increased NO ₂ upstream of the filter. This facilitates the regeneration burnout process and allows the regeneration temperature to be reduced to about 380 ° C. However, depending on the engine duty cycle, the exhaust flow temperature may never exceed the regeneration target temperature of 380 ° C., so another approach to assist regeneration may be required.

  One known solution to this is described in Non-Patent Document 1, where heating with a convection section and a subsequent heat-dissipation section to raise the trap temperature before the exhaust gas enters the particle trap. Run through the module. Alternatively, it is known to provide auxiliary local heating to the filter to increase the approach temperature and allow regeneration, or to rely on fuel-derived catalysts. Auxiliary heating requires a more complex connection to the onboard power system, which may not be made large enough to handle the additional load, and is costly and difficult to maintain It also has a drawback because it increases. On the other hand, the same results can be obtained with fuel-derived catalysts, but concerns are growing about other emissions produced during this regeneration process.

  Another known solution is described in Non-Patent Document 2. According to Non-Patent Document 2, it is possible to regenerate the catalyst by injecting fuel into the exhaust stream. However, if the fuel injection rate is too high, the fuel will not react and will slip through the catalytic converter and create undesirable emissions such as white smoke.

Further problems can occur with known systems. The regeneration process is strongly dependent on the temperature and thus on the type and usage of the vehicle, for example the duty cycle of the vehicle. Therefore, the dust filtering system cannot be applied without understanding the duty cycle of the engine in order to create an exhaust gas temperature profile model for reliably regenerating the filter with exhaust gas. For example, in a bus application, the bus may have a temperature trend that accumulates on a vehicle-only road route that is known to reach the correct regeneration temperature, but the bus continues to have exhaust temperatures that are Additional problems are added because enough local routes can be allocated. In particular, the best temperature for the catalytic converter can be achieved after a high engine load period followed by an idling period. Under such conditions, the exhaust components are already hot and there is oxygen available for fuel oxidation. However, as the idling period increases and the engine begins to cool, it is more difficult to maintain the temperature at the front of the catalytic converter. In particular, under conditions of cold engine, such as low duty cycle operation, heat to vaporize the fuel is taken from the front of the catalytic converter. The vaporized fuel further enters the catalytic converter where it is oxidized. The resulting heat is conducted to the front of the catalytic converter and is used to vaporize the fuel. However, if too much fuel is injected, a problem arises because the front part of the catalytic converter is rapidly cooled, leading to a temperature rise.
Zikoridse et al., “Particulates Trap Technology for Light Duty Vehicles with a New Regeneration Strategy”, SAE Technical Papers Series No. 2000-01-1921 McGill et al., Oakridge National Laboratory, “Demonstration of the effectiveness of a NOX absorber and particle filter system on a light-duty diesel vehicle” , Windsor Workshop 2001 (Windsor, Ontario, Canada)

  Provided is a highly versatile filter regeneration control means for an exhaust filter of a vehicle.

  The invention is set out in the claims.

  As a result, the present invention allows implementation of a control scheme applicable to multiple usages and duty cycles.

  Embodiments of the present invention will be described by way of example with reference to the drawings.

  Referring generally to FIG. 1, FIG. 1 illustrates in block diagram the major components of an engine incorporating a system according to the present invention. It will be appreciated that air is supplied from the intake manifold 10 to the engine 12 and exhaust is supplied from the engine 12 to the exhaust manifold 14. The exhaust stream then passes through the exhaust conduit 16a toward the catalytic converter 18 for reducing CO and HC. The exhaust stream with reduced CO and HC then passes through the exhaust conduit 16b to the diesel particulate filter (DPF) where particulate matter such as soot is removed from the exhaust stream, and the exhaust stream passes through the exhaust conduit 16c. To do.

  A fuel injector 22 is attached to the exhaust conduit 16a in proximity to the exhaust manifold. Alternatively, the fuel injector 22 can be directly attached to the exhaust manifold 14 to take advantage of the maximum exhaust flow temperature. The fuel metered into the exhaust stream by the fuel injector 22 is oxidized by the catalytic converter 18 and thus supplies heat. This heat assists in raising the temperature of the DPF 20 to an appropriate level to allow subsequent combustion with oxygen. As will be discussed in more detail below, this approach provides significant temperature increases up to the required approximately 550 ° C, but more preferably as high as 650-700 ° C. Temperatures above this range can have the effect of damaging the catalytic converter.

  The system controls the fuel injector 22 and receives signals from sensors 26, 28, 30, 32, 34, 36, 38 and 40 as will be described in more detail below. And a regeneration controller that can be made independent of or part of the ECU 24. Based on the detected signal, the ECU 24 implements a fuel injection method by the fuel injector 22 in order to obtain a desired regeneration level of the DPF 20. In particular, the sensed signal is used to determine when to turn the fuel injector on and off and thus start and stop regeneration. At the start of fuel injection, it was detected that the amount of adsorbed particulate matter in the DPF exceeded a predetermined amount of adsorbed particulate matter, and a temperature condition suitable for starting the catalytic reaction with the injected fuel in the catalytic converter 18 was detected. Sometimes be provoked. Similarly, fuel injection is stopped when it is detected that the amount of adsorbed particulate matter has fallen below a predetermined threshold or when a temperature condition insufficient to support regeneration is detected. The amount of adsorbed particulate matter is determined as a function of the pressure drop across the DPF 20 and the mass flow rate through the engine and the temperature detected at the catalytic converter 18. The ECU 24 also controls the fuel injection process via the fuel injector 22 to ensure that an appropriate regeneration level is achieved. In particular, fuel injection is controlled as a function of the temperature of the catalytic converter 18 to avoid unburned fuel resulting from over-injected fuel from slipping through the catalytic converter and producing undesirable emissions in the form of white smoke. Is done.

As a result of this approach, a regeneration method is provided that is fully controlled by on-board components that do not require any operator involvement and can be achieved for any duty cycle operation of the vehicle. In particular, this regeneration method is accomplished by artificially raising the system operating temperature to about 550 ° C. to ensure that exhaust gas is burned out by the high pressure fuel injection system and that the exhaust gas temperature is increased downstream of the catalytic converter 18. Is done. As will be explained in more detail below, the fuel can be injected at high pressure (100 bar (10 ⁷ Pa)) or low pressure (2 bar (2 × 10 ⁵ Pa)) depending on the operating conditions of the engine.

  Specific configurations and schemes are discussed below along with further optimization.

Referring to FIG. 1 in more detail, the catalytic converter 18 is a high platinum addition metal catalyst of cordierite metal or silicon carbide material with a mineral thinning coating that is known to reduce CO and HC to 95%. Have DPF 20 is a silicon carbide filter that has been shown to reduce particulate matter by 95% and remove almost all visible black smoke. The sensors include an intake manifold absolute pressure (IM _PA ) sensor 26 and an intake manifold absolute temperature (IM _TA ) sensor 28 provided in the intake manifold 10. An engine speed (ES) sensor 30 is provided in the intake manifold to measure cylinder intake manifold pressure changes that vary in the engine 12 or each time the cylinder port opens and thus represent the engine speed. In order to detect the temperature (T1) of the exhaust gas entering the engine exhaust manifold 14, a temperature sensor 31 is provided in front of the fuel injector 22, and another temperature ( _TCI ) sensor 32 is provided on the intake surface of the catalytic converter. The sensor 34 detects the gas temperature (T _CO ) on the discharge surface of the catalytic converter 18. The sensor 36 detects the pressure at the inlet to the DPF 20 and enables measurement of the pressure drop _{across the DPF} (P _DPF ) relative to atmospheric pressure (ie, the pressure at the DPF outlet). The sensor 40 detects the temperature (T _DO ) of the gas exiting the DPF 20. The sensor has an elongate probe that extends into the body of each component where temperature is sensed. The sensor extends radially into the component so that the axial position of the sensor can be accurately determined. This is important, for example, when it is necessary to obtain the temperature at each axial end of the component.

  The manner in which this configuration and the value of a particular sensor are used to implement the control scheme of the present invention can be better understood with reference to FIG.

In block 200, the ECU monitors whether the adsorbed particulate matter amount F _load of the DPF 20 exceeds a predetermined threshold value. The value of F _load is expressed by Equation 1:

Can be obtained from Where c is a constant that can be set during system development or obtained from a lookup table.

Equation 1 represents the relationship between the pressure drop P _DPF across the filter, the mass flow rate and the amount of adsorbed particulate matter. The P _DPF becomes higher as the carbon is adsorbed on the filter until the filter needs to be regenerated to remove the carbon. However, since P _DPF is proportional to the mass flow rate of the gas passing through the filter, it is necessary to normalize P _DPF with respect to the exhaust mass flow rate.

The exhaust mass flow is determined by the amount of air taken in each engine stroke, which is determined by the temperature of the air in the intake manifold (IM _TA ) and its absolute pressure (IM _PA ) and the engine speed (ES). The amount of air taken in will decrease proportionally as IM _TA increases, and increase proportionally as IM _PA and ES increase. This is expressed in Equation 1 above. The threshold that the F _load must exceed in order to initiate regeneration can represent the total amount of adsorbable particulate matter in the filter or a portion of the amount of adsorbable particulate matter in the filter, as a constant in the control software. Can be stored or set during development or installation.

It will be appreciated that other _{ways in} which the F _load can be monitored are possible. For example, the peak value of _PDPF can be monitored to identify significant trends. For example, if the peak value increases substantially, it can be identified as a result of reaching the adsorbed particulate matter amount threshold. Appropriate behavior that allows such recognition can be set. In this case, the short-term fluctuation of the _PDPF resulting from the opening and closing of the exhaust valve of the engine cylinder can be ignored because only the maximum value is obtained. A maximum value curve can be created by interpolating between intermittent maximum values. As a result, the amount of adsorbed particulate matter can be determined without referring to the engine speed.

In block 202, the ECU 24 further determines whether the catalytic converter 18 is at a temperature suitable for combustion of the fuel injected into the exhaust stream. In particular, since the catalytic converter will only promote the oxidation of the fuel at approximately 230 ° C. or more high temperature, the system checks that none of the intake air temperature T _CI and the exhaust temperature T _CO is exceeded threshold temperature. If both the amount of adsorbed particulate matter and the catalytic converter temperature exceed the respective threshold values, in block 204, the ECU starts the fuel injection process. The system then monitors for an initiating event that would stop the regeneration process. In block 206, the system monitors whether the F _load , as given in Equation 1 above, falls below a lower threshold that represents an appropriate decrease in the amount of adsorbed particulate matter. If the F _load falls below the threshold, fuel injection is stopped at block 208. The system further monitors at block 210 for a decrease in the temperature of the catalytic converter 18 such that combustion of the injected fuel will no longer occur as a result of no fuel injection occurring. In particular, the system can monitor _TCI and _TCO to achieve the same 230 ° C threshold as initiating fuel injection in block 202, in which case _TCI and _TCO can be lowered below the lower temperature threshold. Confirm whether or not. If it falls, the fuel injection is similarly stopped in block 212. As a result of the fuel injection stop, the required temperature rise cannot be achieved. Once the catalyst converter becomes a high temperature after the fuel injection, even lowered T _CI it is possible to maintain the required T _CO, thus desirably T _CO is lowered below the threshold simply watching the T _CO Note that it is only necessary to check whether or not. Alternatively, it will be appreciated that the fuel injection process can vary depending on the temperature difference across the catalytic converter, which gives an accurate reflection of the temperature course within the catalytic converter.

Catalytic converter temperature drops can occur for a variety of reasons, for example, due to vehicle duty cycles. One particular example would be a reduction in exhaust temperature when the vehicle engine load is reduced. In addition, the temperature _TCO can be monitored to identify when the catalytic converter temperature exceeds the damage threshold.

As an alternative, the T _CO from T _CO set temperature to be achieved by the system fuel injection (as further discussed in detail below), when, for example, a long time over a larger 30 ° C. than 10 seconds, the deviation occurs You can stop playback.

  In block 214, the system further monitors to see if a timeout condition has been met. Thus, a timer is started at the start of the regeneration process at block 204, and if the timer exceeds a threshold, eg, 5 minutes, fuel injection is also stopped at block 216.

The system further, at block 218 monitors the temperature _{T DO} of DPF _{20, T DO} checks whether exceeds a self-sustaining threshold. When regeneration is initiated, a rapid rise in the temperature of the DPF is initiated, and such a high T _DO indicates that regeneration has started and fuel injection can be stopped. Since regeneration is a self-sustaining exothermic reaction, subsequent fuel injection is not required, but the fuel injection level required to maintain regeneration, for example, lower than the level required to initiate regeneration, but with the exhaust stream temperature being lower. It may be desirable to introduce a level that is sufficient to maintain the desired level.

The system further at block 222 monitors the temperature _{T DO} of DPF _20, checks whether _{T DO} is exceeded safe operating threshold, for example a 1000 ° C.. If T _DO exceeds this operational threshold, fuel injection and / or regeneration is stopped and a warning condition is indicated at block 224.

It will be appreciated that the fuel injection process at block 204 is preferably controlled to achieve optimal efficiency and emissions reduction. In particular, it has been found that if too much fuel is added, the fuel simply passes through the catalytic converter 18 without being oxidized and produces white smoke, and also has a cooling effect on the catalytic converter and lowers its temperature. . For example, only a small amount of fuel should be added at a starting temperature of 230 ° C., but higher fuel injection rates can be tolerated as the temperature increases. With reference to Table 1 and FIG. 3, a suitable control scheme can be further seen.

At block 300, at the beginning of the fuel injection process, the _TCO set temperature is set as a measured value (reach 230 ° C.). From the look-up table corresponding to Table 1, the ramp rate corresponding to the _TCO set temperature can be obtained as 1 ° C./second. As a result, fuel injection is controlled to provide a T _CO increase in this rate. This can be done, for example, by changing the amount or frequency of fuel injection. If the injector is switched on for a short time every 20 milliseconds, the time that the injector remains on can be varied to meet the required amount of fuel entering the exhaust. This time can be determined, for example, from a separate look-up table determined during system development, or as a result, the fuel injection metering can be quickly adjusted to converge the temperature rate to the desired value. It can be determined using a feedback technique such as a PID (proportional / integral / derivative) control algorithm. For situations where engine speed and load are high, the amount of fuel injection can be reduced, thus preventing unwanted fuel passage. Thus, the values in Table 1 may vary to different values depending on engine speed and / or load.

The system continues to measure T _CO, at block 302, the measured T _CO confirms whether reaches the next set temperature (270 ° C. in the first first from Table 1). If so, at block 304 the _TCO set temperature is set to the next set temperature (ie 270 ° C.) and the set temperature ramp rate is determined accordingly. In the example shown, the set temperature ramp rate is increased to 2 ° C./second and the fuel injection process is metered accordingly to achieve this. As a result, the ramp rate is initially moderate, but becomes higher as the catalytic converter temperature rises and more fuel is oxidized. In block 302, the system takes the time that the fuel injection is metered according to the ramp rate as shown in Table 1 and is estimated to take the time to reach the next set temperature or slightly longer. Also, a check is performed to ensure that the time-out time that can be individually determined for each set temperature value is not exceeded. Beyond the timeout period, regeneration is aborted because the desired temperature ramp rate increase cannot be sustained to initiate regeneration.

Maximum temperature level to play at that temperature is Okoshihatsu, the process is repeated until T _CO reaches for example 550 ° C.. Overshoot is avoided, der in order to ensure that the risk of white smoke caused by unburnt fuel is reliably reduced, the set temperature ramp as T _CO approaches the upper limit can be seen that has been lowered again Let's go. When the _TCO set temperature reaches 550 ° C., fuel injection is stopped so as not to exceed the set temperature value. This may be appropriate in situations where regeneration is occurring as a self-sustaining exothermic reaction. However, there may be situations where regeneration is not self-sustaining and therefore it may be necessary to inject fuel at a set temperature of 550 ° C., ie at 0 ° C./sec ramp rate. Again, the fuel injection rate is defined by both engine speed and load and temperature _TCO . It can be seen that the timeout time for high temperature values is also considerably shortened to avoid excessive fuel injection and limit the sum of the maximum allowable times for each individual step to the maximum time for the fuel injection process. I will.

  As a result, when started, fuel is injected to achieve a rapid temperature rise over the catalytic converter 18 and increase the probability of successful regeneration. The possibility of fuel slipping through the catalytic converter, resulting in undesirable fuel emissions that appear as white smoke, is avoided by ensuring that the fuel is not injected at a rate that is too high, which is the rate of temperature rise (and hence fuel injection). This is achieved by determining the relationship between the temperature and the catalytic converter temperature. As discussed above, it will be understood that further parameters may be introduced to determine the ramp rate. For example, increasing the engine speed may reduce the fuel injection rate because the fuel duration in the catalytic converter is reduced at higher speeds. Catalytic converter temperature can also be measured at more than one point along the length of the converter to allow optimization of the fuel injection rate.

Another fuel injection rate scheme can be implemented based on the known maximum injection rate. The fuel injection rate is set so that fuel slip does not occur or the maximum temperature is not exceeded. The maximum rate of fuel injection is

Given by. FR is the final fuel injection rate at a specific engine operating condition in milliliters / second. FRES is the fuel injection rate with respect to the measured engine speed. FRT1 is a fuel injection rate related to the engine exhaust manifold temperature. FRT _CI is a fuel injection rate on _{T CI.} FRT _CO is a fuel injection rate for _{T CO.}

  Thus, the final amount of fuel injected depends on the operating temperature in the engine exhaust manifold, the temperature across the catalytic converter, and the engine speed. The final fuel injection rate is gradually reduced as the catalytic converter temperature approaches the maximum operating temperature. This results in the desired controlled temperature rise rate even while the engine conditions are changing rapidly when the engine is in use.

The fuel injection rate for each of these parameters is determined from a look-up table entered in the ECU 24 to suit the vehicle type and vehicle application. An example of a look-up table is as follows, where each parameter of the table is determined depending on the type and application of the vehicle, the size of the engine or any other suitable parameter.

  It will be appreciated from Equation 2 that the final fuel injection rate is zero when one or more of the parameters in Table 2 is zero. This provides system failsafe and no fuel is injected when conditions are not optimal for regeneration.

As can be seen from Table 2, the maximum fuel injection rate is generally designed to be highest when the engine is operating hard and the engine core temperature is high, but then the engine enters idling. During idling, the oxygen content of the exhaust is large, and a larger amount of fuel can be burned. When all the temperature T _CI and T _CO of the front and rear of the catalytic converter is the optimum temperature, the maximum fuel injection profile peaked, in order to prevent the catalytic converter temperature is too high damage to the catalytic converter The fuel injection amount is reduced. Furthermore, as discussed above, fuel injection is only possible when the filter back pressure F _load is above a threshold. This F _load parameter can be put into Equation 2 as a product term with a binary value of 1 or 0, thus providing an additional failsafe mechanism.

Fuel injection at high pressure, eg, 100 bar (10 ⁷ Pa), has been found to be effective because it produces the most effective dispersion and atomization of the injected fuel in the exhaust manifold and exhaust stream. . An injection repetition rate of 50 Hertz allows an appropriate degree of control. In general situations, the oxygen content of the exhaust gas is sufficient to allow regeneration, but if necessary, additional steps can be taken to ensure that sufficient oxygen is present in the catalyst. Of course.

Alternatively, as shown in the side cross-sectional view of FIG. 5a and the end view of FIG. 5b, a compressor (see FIG. ⁵ ) for feeding air into the inlet 70 of the injector head 22, generally at a pressure of 2 bar (2 × 10 ⁵ Pa). Not shown) is used. The injector head is mounted radially between the sensor 32 and the intake surface of the catalytic converter in the exhaust gas flow of the conduit 16a, aligned with the exhaust gas flow direction in the conduit, and in the same direction as the exhaust gas flow direction. Guide the fuel in the direction. The fuel may be a peristaltic pump (not shown), for example of the type supplied by Rietschle Thomas UK Ltd, or any one that allows metering at a constant milliliter / minute to the outlet fuel point 52 adjacent to the outlet opening 54. It is metered by any suitable pump. The peristaltic pump is driven by a step motor with high step resolution so that the fuel injection rate can be finely controlled.

  In operation, compressed air enters the injector head 22 through the inlet 70 and fuel enters the injector head through the fuel inlet 72. Air and fuel travel through separate passages 74 and 76 to respective outlets 54 and 52. Air and fuel mix at the junction at the exit point. In a preferred embodiment, the air flow is maintained for a short time, for example 5 seconds, to ensure that all of the remaining fuel is consumed after the end of the fuel flow. With such a configuration, the fuel is effectively atomized and dispersed by the high velocity turbulence generated by the air flow through the outlet opening, and at the same time, milliliter delivery of fuel to the catalytic converter is possible. Furthermore, air acts only as a means of dispersing the fuel rather than propelling it. The corresponding low pressure operation means that the fuel drawn into the compressed air and mixed in the conduit will not be injected at high speed, for example through a converter, and will therefore hit the hot TPF which will of course cause considerable harm. There is nothing. Furthermore, fuel can be injected directly from existing fuel pipes or existing fuel tanks, and no auxiliary reservoir is required.

  It will be appreciated that the operation of the system can be further improved by maintaining a history of vehicle operation and regeneration processes. This can be used, for example, to improve the control strategy in various ways. For example, it can be seen that the regeneration efficiency increases at higher or lower catalytic converter temperatures so that a reasonable starting point can be adjusted accordingly. Alternatively, it can be seen that a higher or lower DPF pressure drop corresponds to the completion or start of regeneration so that the fuel injection process can be modified accordingly. Furthermore, the particular fuel injection rate scheme discussed above with reference to Tables 1 and 2 can be adjusted, for example, by adjusting a set temperature step value, a desired combustion rate, or a fuel injection amount. Furthermore, the system can identify the relationship between fuel injection level, catalytic converter temperature and temperature rise so that the desired ramp rate can be achieved more quickly. Furthermore, further information can be obtained from the stored operation history. For example, if one or more specific duty cycles are frequently applied, the system will recognize from the vehicle operating environment that one of these duty cycles has been input and control accordingly. You can adjust the formula. For example, if a duty cycle is accompanied by a significant exhaust temperature rise, the fuel injection process can be weakened.

  More generally, it can be seen that the ramp rate changes inversely with the difference between the temperature set point and the temperature mid-point between the upper limit set point and the adjustable set point. Thus, for example, by selecting an “intermediate point” that can not be accurately centered between the upper and lower temperature set points and introducing appropriate constants, a more complex ramp rate process is obtained. be able to. This can be adjusted for each cycle based on the recorded playback process history data. Alternatively, a more complex look-up table can be provided that can also be dynamically adjusted.

  Referring to FIG. 4 where like reference numerals in the other figures refer to like parts, further improvements to this configuration are shown. In particular, it will be seen that the fuel piping 400 towards the fuel injector 22 comprises a chamber portion that covers or passes through a region having hot water recirculated from a radiator or engine room. As a result, the fuel to the fuel injector 22 is preheated using waste heat, so that high temperatures are more easily achieved.

  Another improvement is shown in FIG. 6 in which an electric heater 60 is placed just in front of the front face 62 of the catalytic converter 18. The main heat transfer means from the heater 60 to the catalytic converter 18 is radiation. This is more efficient than using the exhaust gas to transfer heat by convection because a large amount of power is required to obtain a significant temperature rise of the exhaust gas.

  This is further enhanced by catalyzing the surface of the heater 60. A relatively low power (500 W) heater can raise the temperature significantly above the exhaust temperature. Therefore, the catalyst material on the heater surface can be brought to an active temperature even when the engine is idling. This heat is then applied to the front of the catalytic converter 18 and thus achieves a major temperature rise. A temperature sensor 64 is additionally placed adjacent to the heater to allow control of power to the heater and / or control of the amount of fuel injected according to Equation 2, thus preventing damage to the catalyst coating due to overheating. Used for.

  The various elements and components used to implement the invention are well known to those skilled in the art and need not be discussed at length here. For example, any suitable pressure sensor, temperature sensor, and engine speed sensor can be applied, and any suitable fuel injector can be retrofitted to the exhaust manifold. The system can be controlled by a newly designed or existing engine control unit that implements control techniques and algorithms as discussed above in software or hardware. The control algorithm is implemented using a microcontroller and digital logic with appropriate analog inputs to the A / D converter. If the vehicle's operational history is maintained, the operational history can be stored in any suitable form in the ECU's memory or elsewhere.

  As a result of the above-described configuration, it is possible to implement an effective and flexible exhaust filter regeneration process control regardless of the type of vehicle or duty cycle to be introduced, and to quickly and efficiently regenerate while reducing emissions to a minimum. It becomes possible. Furthermore, playback is performed on demand when needed, not during a predetermined period.

  It will be appreciated that the invention can be applied to any suitable engine or fuel type, and fuel injection can be performed to any suitable portion of the exhaust stream. The approach as described above can be adapted to any suitable temperature dependent exhaust treatment process or other temperature raising mechanism that relies on fuel injection. Fuel injection can be metered by adjusting fuel injection timing, fuel injection rate or fuel injection pulse duration, fuel injection pressure change or fuel type change. Furthermore, control can be implemented using any suitable sensors and injectors using appropriate parameters and exhaust flow components that are detected for engine operation.

1 is a simplified block diagram illustrating an engine that performs an exhaust filter regeneration process in accordance with the present invention. FIG. It is a flowchart which shows the process implemented in a reproduction | regeneration process control system. It is a flowchart which shows the process implemented. FIG. 6 is a simplified block diagram illustrating a further improved approach to enhancing the playback process. It is a figure of the injector head of this invention It is a figure of the injector head of this invention 1 is a schematic view of a catalytic electric heating element.

Explanation of symbols

10 Intake Manifold 12 Engine 14 Exhaust Manifold 16a, 16b, 16c Exhaust Conduit 18 Catalytic Converter 20 Diesel Particle Filter (DPF)
22 Fuel Injector 24 Engine Control Unit (ECU)
26, 28, 30, 32, 34, 36, 38, 40 Sensor 31 Temperature sensor

Claims (33)

  A method for controlling an exhaust filter regeneration process in cooperation with a catalyst processing element, in which fuel is injected into an exhaust stream to increase the exhaust stream temperature, comprising the step of metering fuel injection depending on the exhaust stream temperature A method characterized by comprising:   The fuel injection is metered by controlling one of a fuel injection rate, a fuel injection pulse duration, a fuel injection amount, a fuel injection pressure change and a change in the type of fuel injected. The method of claim 1.   The method according to claim 1 or 2, wherein the exhaust stream temperature includes a temperature of the exhaust stream at an outlet of the catalytic treatment element.   4. The method of claim 3, wherein the fuel injection is further metered depending on the temperature of the exhaust gas coming from the engine and the temperature at the inlet of the catalytic treatment element.   5. The method according to claim 1, further comprising the step of starting fuel injection into the exhaust stream when the amount of adsorbed particulate matter in the filter exceeds a starting value.   Either when the amount of adsorbed particles on the filter decreases to a predetermined determination threshold, when the temperature of the catalyst processing element falls below or exceeds the stop threshold, or when the regeneration process time exceeds the time threshold 6. The method according to claim 1, wherein the method is stopped at that time.   The method according to any one of claims 1 to 6, further comprising a step of recording a reproduction process history and a step of modifying the reproduction process based on the recorded history.   The method according to any one of claims 1 to 7, further comprising the step of preheating the injected fuel with the waste heat of the vehicle.   9. A method according to claim 1, wherein fuel is mixed with compressed air at the injection head prior to injection into the exhaust stream.   The method according to claim 9, wherein the supply of fuel to the injection head is stopped at a predetermined time prior to the stop of the supply of compressed air.   In a method for initiating an exhaust filter regeneration process, a step of obtaining a filter adsorbed particulate matter value as a function of filter pressure and exhaust mass flow, and a regeneration process when the filter adsorbed particulate matter amount exceeds a predetermined value. A method comprising the step of starting.   12. The method of claim 11 including the step of injecting fuel into the exhaust stream at the start of the exhaust filter regeneration process.   A method for initiating an exhaust filter regeneration process includes a step of measuring a filter pressure peak value and a step of identifying a point in time when the amount of particulate matter adsorbed by a filter exceeds a predetermined value from the measured peak value. how to.   In a method for initiating an exhaust filter regeneration process, in cooperation with a catalyst treatment element, fuel is injected into the exhaust stream to increase the exhaust stream temperature, obtaining a temperature value of the catalyst treatment element and the obtained A method comprising initiating the regeneration process when a temperature value exceeds a predetermined value.   Obtaining a filter adsorbed particulate matter value as a function of filter pressure and exhaust mass flow and initiating the regeneration process when the filter adsorbed particulate matter value exceeds a predetermined value. The method according to claim 14.   In a method for controlling an exhaust filter regeneration process, a step of implementing an exhaust flow temperature control method, a step of monitoring a change in exhaust flow temperature and at least one control parameter, a correlation between the change in exhaust flow temperature and the control parameter And a step of adjusting the temperature control method based on the obtained correlation.   17. An exhaust filter regenerator comprising a fuel injector configured to be attached to an exhaust flow conduit and a controller for controlling the fuel injector to implement the method of any one of claims 1-16. Features device.   An exhaust filter regenerator comprising an exhaust flow conduit and a fuel injector attached to the exhaust flow conduit and configured to inject fuel in the exhaust flow direction.   The fuel injector has a fuel intake channel and an air intake channel, each of the fuel intake channel and the air intake channel has an outflow end, and the outflow end of the air intake channel and the outflow end of the fuel intake channel 19. The exhaust filter regeneration device according to claim 18, wherein the exhaust filter is disposed adjacent to each other at the fuel injection port.   The exhaust filter regeneration device according to claim 19, wherein the fuel suction channel is connected to a fuel pump, and the air suction channel is connected to a compressor.   The exhaust filter regeneration device according to claim 20, wherein the fuel pump is a peristaltic pump. 21. The exhaust filter regenerator of claim 20, wherein the compressor is configured to operate in a pressure range of 2 to 200 bar (2 x 10 < ⁵ > to 2 x 10 < ⁷ > Pa).   The exhaust filter regeneration device according to any one of claims 17 to 22, wherein an electric heater is disposed in front of an exhaust gas inflow surface of the catalyst processing element.   The exhaust filter regeneration device according to claim 23, wherein the electric heater is formed of a catalyst processing element.   The exhaust filter regeneration device according to any one of claims 17 to 24, wherein the fuel injector draws fuel directly from a fuel tank or a fuel pipe of a vehicle.   The exhaust filter device according to any one of claims 17 to 25, further comprising an exhaust filter component and a sensor extending in a radial direction in the exhaust filter component.   27. An exhaust filter regenerator according to any one of claims 17 to 26, further comprising a fuel conduit for supplying fuel to the fuel injector, wherein the fuel conduit is preheated by any waste heat. .   An engine or vehicle comprising the device according to any one of claims 17 to 27.   A computer program comprising an instruction set configured to implement the method of any one of claims 1-16.   30. A computer configured to operate under the instructions of the computer program of claim 29.   An engine control unit configured to carry out the method according to any one of the preceding claims.   A computer readable medium having stored thereon an instruction set for carrying out the method according to any one of claims 1 to 16.   A method or apparatus substantially as herein described with reference to the drawings.

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