DE102008050019B4 - System and method for variable power distribution for zone-wise regeneration of an electrically heated particle filter - Google Patents

Abstract

A system comprising: a particulate matter filter (34) comprising a plurality of zones (1, 2, 3, 4, 5); an electric heater (35) comprising a plurality of heater segments (201), each one of the zones (1 , 2, 3, 4, 5), wherein the electric heater (35) is located upstream and near the particulate filter (34); anda control module (44) which selectively provides a first energy input into a first of the zones (1, 2, 3, 4, 5) by means of a first of the heater segments (201) in order to trigger regeneration in the first zone, the control module ( 44) selectively provides a second energy input, less than the first energy input, into a second one of the zones (1, 2, 3, 4, 5) using a second one of the heater segments (201) to initiate regeneration in the second zone; characterized in that the plurality of zones (1, 2, 3, 4, 5) are located in a first circumferential zone band and in a second circumferential zone band, the second circumferential zone band surrounding the first circumferential zone band, one within the first circumferential zone band more of the multiple zones is located.

Description

Declaration of government rights

This disclosure was developed in accordance with U.S. Government Order No. DE-FC-04-03 AL67635 with the Department of Energy (DoE). The U.S. government has certain rights in this disclosure.

area

The present disclosure relates to a system according to the preamble of claim 1 and a method according to the preamble of claim 10 for regenerating a particulate matter (PM) filter.

Such a system and a corresponding method are, for example, from the US 4,516,993 A known. Systems and processes which are essentially comparable in terms of type are also based on the DE 37 12 333 A1 and the DE 10 2008 047 126 A1 forth.

With regard to the further state of the art, reference is made to the publications at this point US 5 144 798 A , US 6,167,696 B1 , US 2003/037674 A1 and US 5,972,075 A referred.

background

Internal combustion engines such as diesel internal combustion engines produce particulate matter (PM), which is filtered out of exhaust gas by a PM filter. The PM filter is arranged in an exhaust system of the internal combustion engine. The PM filter lowers the emission of PM generated during combustion.

Over time, the PM filter becomes full. During regeneration, the PM can be burned in the PM filter. Regeneration may include heating the PM filter to a combustion temperature of the PM. There are various ways of performing regeneration, including modifying engine control, using a fuel burner, using a catalytic oxidizer to raise the exhaust temperature with post-injection of fuel, using resistive heating coils, and / or using microwave energy. The resistance heating coils are typically placed in contact with the PM filter to allow heating by both conduction and convection.

Diesel PM burns when temperatures above a combustion temperature, for example 600 ° C, are reached. According to the teaching of DE 42 43 990 A1 it is intended to regulate the heating coil in such a way that the filter temperature lies within a temperature interval, the lower limit of which defines a temperature which is 25 ° C. above the ignition temperature of the particles absorbed in the filter, and the upper limit of which is defined by a temperature, which is at least 50 ° C below the maximum permissible filter temperature.

The start of combustion causes a further rise in temperature. While spark-ignited internal combustion engines typically have low oxygen values in the exhaust gas flow, diesel internal combustion engines have significantly higher oxygen values. While the increased oxygen levels allow rapid regeneration of the PM filter, they can also pose some problems.

PM reduction systems that use fuel tend to reduce fuel economy. For example, many fuel-reducing PM reduction systems reduce fuel economy by 5%. Electrically heated PM reduction systems reduce fuel economy by a negligible amount. However, the longevity of the electrically heated PM reduction systems is difficult to achieve. Furthermore, the electrical heating power of the PM can be significant.

The object of the invention is to reduce the energy required to regenerate a particulate filter.

Summary

This object is achieved with a system with the features of claim 1 and with a method with the features of claim 10.

In an exemplary embodiment, a system is provided that includes a multi-zone particulate matter (PM) filter, an electrical heater, and a control module. The electric heater includes heater segments, each corresponding to a respective one of the zones. The electric heater is located upstream of and near the PM filter. The control module selectively applies a first energy level to a first of the zones by means of a first of the heater segments in order to trigger regeneration in the first zone. The control module also selectively applies a second energy level to a second one of the zones by means of a second one of the heater segments, which is less than the first energy level in order to trigger regeneration in the second zone.

In other features, a method is provided that includes providing a zone particulate matter (PM) filter. An electrical heater, including heater segments each corresponding to a respective one of the zones, is located upstream of and near the PM filter. A first energy level is applied to a first of the zones by means of a first of the heating device segments in order to trigger regeneration in the first zone. A second energy level, which is less than the first energy level, is selectively applied to a second one of the zones using a second one of the heater segments to initiate regeneration in the second zone.

In yet other features, a system is provided that includes a zone particulate matter (PM) filter, an electrical heater, and a control module. The electric heater includes heater segments, each corresponding to a respective one of the zones. The electric heater is located upstream of and near the PM filter. A control module regenerates the zones by selectively applying a different energy level to each of the zones.

Further areas of applicability will become apparent from the description provided herein.

Figure list

• 1 FIG. 14 is a functional block diagram of an exemplary engine system that includes a power distribution system for an electrically heated particulate matter (PM) filter;
• 2nd shows a zone division according to the invention of a zoned inlet heating device for the electrically heated particle material (PM) filter from 1 ;
• 3rd shows an inventive zoning of a zoned inlet heater for the electrically heated PM filter of 1 ;
• 4th FIG. 12 shows an exemplary resistance heater in one of the zones of the zoned inlet heater of FIG 3rd ;
• 5 shows the electrically heated PM filter from 1 having a zoned electric heater;
• 6 shows heating in the zoned electric heater of FIG 1 and 5 ;
• 7 FIG. 12 is a flowchart showing exemplary steps performed by the exhaust temperature entry control module to the electrically heated PM filter prior to starting regeneration;
• 8th FIG. 14 is a flowchart showing exemplary steps for regenerating a zoned electric heater associated with a PM filter;
• 9 12 is an exemplary graph showing redistribution of currents during regeneration of a PM filter; and
• 10th is an exemplary graph of energy input to each of the five zones of 9 .

Detailed description

It goes without saying that corresponding reference symbols designate identical or corresponding parts and features in the entire drawings.

As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and memory that contains one or more software or Execute firmware programs, a combinatorial logic circuit and / or other suitable components that provide the functionality described.

The present disclosure raises the introduced exhaust gas temperature before performing regeneration using an electric heater to allow more stable regeneration of the PM filter. For example only, the intake exhaust temperature may be raised above the maximum exhaust temperature at the PM filter that occurs during normal operation and below a soot oxidation temperature. The temperature of the exhaust gas entering an inlet of the PM filter can be increased by modifying engine control, using a fuel burner, using a catalytic oxidizer to raise the exhaust gas temperature with post-injection of fuel, and / or other suitable approaches.

For example, the exhaust gas temperature can be raised to a temperature range between 340 and 540 ° C. This temperature range is lower than the typical soot oxidation temperature, but higher than the natural exhaust gas temperature. Typically, high efficiency internal combustion engines work cooler than about 300 ° C.

Once the exhaust gas temperature to the PM filter is raised, the electric heater activates heated zones, causing a soot combustion wave to spread down the PM filter channel to clean the filter. This process continues until all of the heater zones are regenerated. If regeneration of the PM filter is performed with an intake exhaust temperature in this elevated temperature range, as described herein, the combustion flame fronts are less likely to extinguish. The increased inlet exhaust gas temperature also creates a smaller temperature delta, which lowers thermal stress on the PM filter.

The electric heater may or may not be zoned. The electrical heater may contact or be spaced from the PM filter. The heater selectively heats all or part of the PM filter. The PM filter may be in contact with, or close enough to, the front of the PM filter to control the heating pattern. The length of the heater can be set to optimize the exhaust gas temperature.

Thermal energy is transferred from the electric heater to the PM filter. The PM filter can be heated by convection and / or conduction. The electrical heater may be zoned to reduce the electrical power required to heat the PM filter. The zones also heat selected downstream parts in the PM filter. By heating only the selected parts of the filter, the magnitude of the forces in the substrate due to thermal expansion is reduced. This allows higher, localized soot temperatures to be used during regeneration without damaging the PM filter.

The PM filter can be regenerated by selectively heating one or more of the zones in front of the PM filter and by igniting the soot using the heated exhaust gas. When a sufficient face temperature has been reached, the heating device can be switched off and the burning soot then cascades down the length of the PM filter channel, which is similar to a burning fuse in a firework. The burning soot is the fuel that continues the regeneration. This process continues for each heating zone until the PM filter is fully regenerated.

The heater zones can be spaced so that thermal stress between active heaters is reduced. Therefore, the total tension forces due to heating are smaller and are distributed over the volume of the entire electrically heated PM filter. This procedure enables regeneration in larger segments of the electrically heated PM filter without generating thermal stresses that damage the electrically heated PM filter.

A greatest temperature gradient tends to occur on the edges of the zoned heaters. Therefore, activating a heater behind the localized voltage zone of another heater enables an active heated regeneration volume without increasing the total voltage. This tends to improve the possibility of regeneration in one driving cycle and reduces costs and complexity since the system does not have to regenerate as many zones independently.

Now referring to 1 is an exemplary diesel engine system 10th shown schematically in accordance with the present disclosure. It is understood that the diesel engine system 10th is merely exemplary in nature and that the zone-heated particulate filter regeneration system described herein can be implemented in various internal combustion engine systems that use a particulate filter. Such internal combustion engine systems may include, but are not limited to, internal combustion engine systems with gasoline direct injection and internal combustion engine systems with homogeneous compression ignition. For ease of explanation, the disclosure is discussed in the context of a diesel engine system.

The internal combustion engine system 10th includes a power distribution system 11 power to an electric heater (HTR) 35 controls. The power distribution system 11 includes a control module 44 , a power source 46 , a circuit breaker module 47 and the electric heater 35 , which has heater segments, the zones of a particulate matter (PM) filter 34 assigned. Exemplary heater segments are shown in 4th shown. The control module 44 includes a pulse width modulation (PWM) module 49 that controls energy, including power and duration of the power applied to the heater segments. The circuit breaker module 47 can be a power distributor, the relay and / or switch 51 includes which are associated with the heater segments. The control module 44 supplies the switches 51 Control signals to transfer power from the power source 46 to allow for the selected heater segments.

A turbocharged diesel engine system 10th includes an internal combustion engine 12th that burns an air and fuel mixture to produce drive torque. The air flows through an air filter 14 into the system. Air passes through the air filter 14 and gets into a turbocharger 18th sucked. The turbocharger 18th compresses those into the system 10th incoming fresh air. The greater the compression of the air in general, the greater the output power of the internal combustion engine 12th . The compressed air then passes through an air cooler 20 before going into an intake manifold 22 entry.

The air in the intake manifold 22 is in cylinder 26 distributed. Although four cylinders 26 illustrated, the systems and methods of the present disclosure may be embodied in multi-cylinder engines, including but not limited to 2, 3, 4, 5, 6, 8, 10, and 12 cylinders. It is also understood that the systems and methods of the present disclosure can be implemented in a V-cylinder configuration. Fuel is delivered through fuel injectors 28 in the cylinders 26 injected. Heat from the compressed air ignites the air / fuel mixture. Combustion of the air / fuel mixture produces exhaust gas. The exhaust gas emerges from the cylinders 26 into the exhaust system.

The exhaust system includes an exhaust manifold 30th , a diesel oxidation catalyst (DOC) 32 and a particle filter (PM filter) arrangement 34 with an inlet heater 35 . The heater 35 can be divided into zones. Optionally, an EGR valve (not shown) returns part of the exhaust gas to the intake manifold 22 back. The rest of the exhaust gas is in the turbocharger 18th directed to drive a turbine. The turbine facilitates the compression of the air filter 14 fresh air intake. The exhaust gas flows out of the turbocharger 18th through the DOC 32 , through the heater 35 and into the PM filter assembly 34 . The DOC 32 oxidizes the exhaust gas based on the air / fuel ratio after combustion. The extent of the oxidation increases the temperature of the exhaust gas. The PM filter arrangement 34 receives exhaust from the DOC 32 and filters out any particles present in the exhaust gas. The inlet heater 35 stands with the PM filter arrangement 34 in contact or is spaced therefrom and heats the exhaust gas to a regeneration temperature, as will be described later.

A control module 44 controls the engine and PM filter regeneration based on various sensed and / or estimated information. The information collected can be from sensors 53 originate or can be based on recorded information and the operating state of the internal combustion engine system 10th to be appreciated.

The sensors can include temperature sensors, engine sensors, and modules, air-related sensors, and pressure sensors. The sensors may include sensors for determining exhaust gas flow values, exhaust gas temperature values, exhaust gas pressure values, oxygen values, intake air flow velocities, intake air pressure, intake air temperature, engine speed, EGR, etc.

The temperature sensors may include an intake temperature sensor, an engine coolant temperature sensor, an engine oil temperature sensor, exhaust gas temperature sensors, PM filter temperature sensors, an ambient temperature sensor, and may include other engine temperature sensors. The intake air temperature sensor can be a signal for a Generate intake air temperature (IAT). The engine coolant temperature sensor may generate an engine coolant temperature (ECT) signal. The engine oil temperature sensor may generate an engine oil temperature (T _OIL ) signal. The exhaust temperature sensors can generate intake, interior, and exhaust exhaust temperature signals associated with a PM filter. The ambient temperature sensor can generate an ambient temperature (AMB) signal.

The engine sensors and modules may include a cylinder air test module, an engine output torque sensor or module, an engine load module, an engine operating time indicator, an engine speed sensor. The cylinder air test module determines the status of air in cylinders of an internal combustion engine. The status can include flow and cylinder air mass, for example. The cylinder air test module determines the status based on air related signals generated by the air sensors and engine output torque. The engine output torque can be measured or estimated directly or indirectly. The internal combustion engine output torque can be measured directly by means of one or more sensors, for example a drive shaft torque sensor, a strain gauge or another torque sensor. Engine output torque may be indirectly estimated based on engine operating parameters, some of which are set forth herein, for example using a lookup table. The engine speed sensor, such as a camshaft, crankshaft, flywheel, or transmission sensor, generates a speed signal that indicates engine speed RPM. The control module can determine the engine speed from the speed signal. It should be noted that the engine speed can also be estimated indirectly based on engine operating parameters.

The air sensors may include an air flow meter, a throttle position sensor, an intake air pressure sensor, and may include other sensors related to air. An air flow meter can be an air mass meter (MAF) that monitors air flow through a throttle valve. The throttle position sensor responds to a position of a throttle valve and generates a throttle position signal TPS. The intake air pressure sensor generates a manifold vacuum signal (MAP).

The pressure sensors can respond to atmospheric pressure and can generate an BARO air pressure signal.

More precisely, the control module estimates 44 the loading of the PM filter arrangement 34 based on the captured and estimated information. If the estimated load is at a predetermined value and the exhaust gas flow is within a target range, a power source can be used 46 electrical current to the PM filter assembly 34 be directed to initiate the regeneration process. The duration of the regeneration process can be based on the estimated amount of particulate matter in the PM filter assembly 34 to be changed.

Electric current is applied to the heater during the regeneration process 35 created. More specifically, the energy can be selected zones of the heater 35 the PM filter arrangement 34 heat each for a predetermined period of time. Through the heater 35 Exhaust gas is heated by the activated zones. The heated exhaust gas flows to the downstream filter of the PM filter arrangement 34 and heats the filter by convection and / or conduction. The rest of the regeneration process can be accomplished using the heat generated by the heated exhaust gas passing through the PM filter.

Now referring to 2nd becomes an inlet heater not zoned according to the invention 35 ' for the PM filter arrangement 34 shown. The electrically heated PM filter arrangement 34 is spaced from the PM filter assembly 34 or arranged in contact with it. The PM filter arrangement 34 includes several spaced heater zones, the zone 1 (with subzones 1A , 1B and 1C ), Zone 2nd (with subzones 2A , 2 B and 2C ) and zone 3rd (with subzones 3A , 3B and 3C ) include. The zones 1 , 2nd and 3rd can be activated during different periods.

When exhaust gas flows through the activated zones of the heating device, regeneration occurs in the corresponding parts of the PM filter, which first took up the heated exhaust gas (e.g. areas downstream of the activated zones), or in downstream areas, which are caused by burning cascades that spread out Soot to be ignited. The corresponding parts of the PM filter that are not downstream of an activated zone serve as voltage reduction zones. In 2nd are for Example the subzones 1A , 1B and 1C activated and the subzones 2A , 2 B , 2C , 3A , 3B and 3C serve as stress reduction zones.

During heating and cooling, the corresponding parts of the PM filter expand downstream of the active heater sub-zones 1A , 1B and 1C thermally and contract thermally. The stress reduction subzones 2A and 3A , 2 B and 3B such as 2C and 3C mitigate one by expanding and contracting the heater sub-zones 1A , 1B and 1C caused mechanical tension. After zone 1 the regeneration has ended, the zone 2nd be activated and the zones 1 and 3rd serve as stress reduction zones. After the zone 2nd the regeneration has ended, the zone 3rd be activated and the zones 1 and 2nd serve as stress reduction zones.

Now referring to 3rd Another exemplary arrangement of a zoned inlet heater 35 " shown. A central part can be surrounded by a central zone, which comprises a first circumferential band of zones. The middle part can be surrounded by an outer part, which comprises a second circumferential band of zones.

In this example, the central part is Zone 1 . The first circulating band of zones includes the zones 2nd and 3rd . The second circulating band of zones encompasses the zones 1 , 4th and 5 . As in the embodiment described above, parts downstream of active zones are regenerated, while parts downstream of inactive zones provide a voltage reduction. As can be seen, one of the zones can be used 1 , 2nd , 3rd , 4th and 5 be activated. The other of the zones remain deactivated.

Now referring to 4th becomes an exemplary resistance heater 200 shown that belong to one of the zones (e.g. Zone 3rd ) from the first circulating band of zones in 3rd is arranged adjacent. The resistance heater 200 may include one or more coils, heater segments, or conductive elements covering the respective zone to provide sufficient heating. The resistance heater 200 includes three (3) heater segments as shown 201 that are electrically conductive.

Now referring to 5 becomes the PM filter assembly 34 shown in more detail. The PM filter arrangement 34 includes a housing 200 , a filter 202 and the zoned heater 35 . The filter 202 can have a rear end plug 208 include. The heater 35 can be between a laminar flow element 210 and a substrate of the filter 202 be arranged. An electrical connector 211 can the zones of the PM filter arrangement 34 supply electrical current as described above.

As is understood, the heater 35 with the filter 202 are in contact or at a distance from it, so that the heating is convection and / or line heating. Between the heater 35 and the housing 200 can be insulation 212 be arranged. From an upstream inlet 214 Exhaust gas enters the PM filter assembly 34 and is passed through one or more zones of the PM filter assembly 34 warmed up. The heated exhaust gas is from the filter 202 added.

Now referring to 6 becomes heating in the PM filter assembly 34 shown in more detail. The exhaust gas 250 passes through the heater 35 and is passed through one or more zones of the heater 35 warmed up. At a distance from the filter 202 the heated exhaust gas travels a distance "d" and is then removed by the filter 202 added. For example, the distance "d" can be ½ inch ( 1 , 27 cm) or less. The filter 202 can have a medium inlet 240 , a channel 242 , a filter material 244 and an outlet 246 have, which is arranged radially outside of the inlet. The filter can be catalyzed. The heated exhaust gas causes PM to burn in the filter, which regenerates the PM filter. The heater 35 transfers heat through convection and / or conduction to a front portion of the filter 202 to ignite. When the soot in the front surface parts reaches a sufficiently high temperature, the heater is switched off. The combustion of soot then cascades through a filter channel 254 down without having to maintain power to the heater.

Now referring to 7 control begins at step 300 . At step 304 the controller determines whether regeneration is required. At step 308 The controller determines whether the exhaust gas temperature to the PM filter is greater than a first temperature _threshold T _TH1 . The first temperature _threshold T _TH1 may be greater than a normal exhaust gas temperature that occurs during normal engine operation and less than a soot oxidation temperature. For example only, the first temperature threshold T _{TH1 can be selected} in the range between 340-540 ° C. For example, the temperature threshold can be selected in the range between 390-490 ° C. Just for example the temperature threshold T _{TH1 can be selected} in the range between 430-470 ° C. For example only, the temperature threshold T _{TH1 can} be selected to be about 440-460 ° C. The term "about" as used herein means +/- 5 ° C.

If step 308 if the answer is no, the internal combustion engine control module raises the exhaust gas temperature at step 312 using any suitable approach. The controller moves from the steps 312 and 308 (if yes) with step 316 away. If step 316 If the answer is affirmative, the controller determines whether the temperature of the PM filter is greater than a second temperature _{threshold value} T _TH2 . If step 316 if the answer is affirmative, the control carries out the regeneration control of the PM filter. The controller moves from the steps 316 (if not) and step 320 with step 324 away.

For example only, the regeneration temperature in the PM filter can be set to approximately greater than or equal to 600 ° C. For example only, the regeneration temperature in the PM filter can be set to approximately greater than or equal to 700 ° C. For example only, the regeneration temperature in the PM filter can be set to approximately greater than or equal to 800 ° C. In one embodiment, a target temperature is set at 900 ° C. The heater segment temperatures can be set approximately equal to or higher than the above temperatures.

Now referring to 8th exemplary steps for regenerating a zoned PM filter are shown. At step 400 control begins and moves to step 404 in front. If the control at step 404 determines that regeneration is required, the controller chooses at step 408 one or more zones.

At step 412 The controller estimates the energy required to reach a minimum temperature on the filter face. The estimated energy includes power and a heating period for applying a fixed or variable power level to the selected zone or to selected parts thereof. The estimated energy is based on at least one of: power, including electrical current and voltage, the predetermined period, exhaust gas flow, and exhaust gas temperature. The estimated energy may also be based on the cross-sectional area associated with the heater segments, the number of zones, resistance properties associated with the zones, and other factors, some of which are described herein. The estimated energy level can be determined based on pressure drop across the PM filter from the inlet to the outlet, as described below.

The change in flow distribution across the zones can be used to estimate the energy level to be supplied. The minimum temperature of the front should be sufficient to start the soot combustion and to create a cascade effect. The minimum temperature of the end face can be set to 700 ° C. or more merely by way of example. The performance can be determined based on the predetermined period or vice versa.

At step 416 the controller activates the heater for the selected zone based on the estimated energy and line, and the predetermined amount of time to apply this power. The heater segments associated with the selected zone are activated. For example, a first energy level with an associated first power level is applied to the heater segments for a first predetermined period of time (duration of power applied). The control module 44 can for example the circuit breaker module 47 signal to deliver power to the heater segments. A pulse width modulated signal can be sent from the control module 44 generated and the circuit breaker module 47 delivered and adjusted to provide the determined energy level.

At step 418 the controller determines whether the predetermined heating period has expired. If step 418 if the answer is affirmative, the control determines at step 420 whether additional zones need to be regenerated. If step 420 if the answer is affirmative, the control moves to step 422 otherwise, control ends at step 428 .

At step 422 the control selects another zone for regeneration. At step 424 The controller estimates energy to be applied to the heater segments that of the selected zone by step 422 assigned. The estimated energy level can be similar to the process of step 412 be determined. The estimated energy level is lower than the energy level at a previously activated zone and / or at the step 416 activated first zone was created. To provide a reduced energy level, the power or the duration over which the power is applied can be reduced. The controller takes into account the number of regenerated and non-regenerated zones when determining the flow distribution. Thus, a second or subsequent level of performance can be created, the is lower than a previous and / or first level of performance. As an alternative or in combination with a decrease in performance, a second or subsequent time can be determined which is less than a previous and / or the first predetermined time. At step 426 the controller activates the selected zone from step 422 by applying an appropriate level of performance over a period of time, at step 424 to provide determined energy level.

The steps described above are intended as illustrative examples; Depending on the application, the steps can be carried out sequentially, synchronously, simultaneously, continuously, during overlapping periods or in another order.

Now referring to 9 An exemplary graph illustrates the redistribution of flow during regeneration of a PM filter. The graph includes currents for each regeneration state while regeneration of a five (5) zone PM filter is shown. Five regeneration states are shown. Five bars are shown for each of the five states. Each bar is assigned to a specific zone of the PM filter.

The first state is assigned to the PM filter before regeneration when the five zones are loaded with soot or are essentially loaded with soot. The second state is assigned after a first zone has been regenerated. Thus, as shown, the flow in the first zone increased. As the flow increases in the first zone, the flow decreases in the other zones. The increase in the flow rate enables the application of a reduced energy level for the regeneration of the non-regenerated zones. When a zone is regenerated, the lack of soot in that zone causes a drop in flow resistance, which leads to increased flow. Zones that are created later have the advantage of reduced flow due to their high flow resistance caused by soot deposition. Decreased flow helps transfer energy from an electric heater to exhaust gas and the PM filter.

The first regenerated zone can get a maximum energy level and subsequent zones can get an increasingly lower energy level. The distribution of energy and / or power can follow the distribution of the flow.

The third state is assigned after the first and second zones are regenerated. Thus, as shown, the flow decreases in the first and second zones, while the flow decreases in the third, fourth and fifth zones. The fourth and fifth states have progressive results similar to those of the third state.

Now referring to 10th is an exemplary graph of energy input to each of the five zones of 9 shown. The vertical axis is energy in percent, with 100% corresponding to a maximum energy value. Five regeneration states are shown. Two bars are shown for each of the five states. The first bar represents an example where an even energy level is applied to each of the five zones. The second bar represents a progressively decreasing amount of energy that is applied to each of the five zones. The first state is assigned to the PM filter before regeneration, the five zones being loaded with soot or essentially being loaded with soot. The second state is assigned when the first zone is regenerated. The third state is assigned when the second zone is regenerated. The fourth state is assigned when the third zone is regenerated. The fifth state is assigned when the fourth zone is regenerated.

The graphs of 9 and 10th are examples in which the zones of a PM filter are modeled as separate connected PM filters, each with approximately the same soot load. The energy values can be adjusted to take into account uneven amounts of soot loading. The pressure drop across a PM filter with clean and loaded zones can be represented as a function of various factors. The main factors can include flow and soot loading.

For example, the pressure drop of a clean PM filter can be represented as provided by equation [1]. The linear term represents the pressure loss due to channel flow and the Darcy term flow through a soot layer and a wall of the PM filter. The quadratic term represents the losses due to expansion and contraction at the inlet of the PM filter and at the outlet of the PM filter as well as the second order inertia losses through the wall. $$\Delta P=\frac{\mu Q_G}{\mathrm{2nd}{V}_{eff}}{\left(D+w_0\right)}^{\mathrm{2nd}}\left[\frac{w_0}{K_{0}D}+\frac{\mathrm{8th}F{L}_{eff}^{\mathrm{2nd}}}{\mathrm{3rd}{D}^{\mathrm{4th}}}\right]+\frac{{\rho }_G{Q}_G^{\mathrm{2nd}}}{V_{eff}^{\mathrm{2nd}}{D}^{\mathrm{2nd}}}{\left(D+w_0\right)}^{\mathrm{4th}\left[\frac{\mathrm{2nd}\zeta L_{eff}^{\mathrm{2nd}}}{D^{\mathrm{2nd}}}+\frac{\beta {\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="DE102008050019B4\_0012.png"\; state="\{\{state\}\}">w</figure-callout>}}_0}{\mathrm{4th}}\right]}$$

As another example, a pressure drop across a PM filter loaded with soot (cake layer) is provided by Equation [2]. $$\begin{array}{l}\Delta P=\frac{\mu Q_G}{\mathrm{2nd}{V}_{eff}}{\left(D+w_0\right)}^{\mathrm{2nd}}\left[\frac{w_0}{K_0^{\text{'}}D}+\frac{1}{\mathrm{2nd}{K}_s}\text{ln}\left(\frac{D}{D-\mathrm{2nd}w}\right)+\frac{\mathrm{4th}F{L}_{eff}^{\mathrm{2nd}}}{\mathrm{3rd}}\left(\frac{1}{{\left(D-\mathrm{2nd}w\right)}^{\mathrm{4th}}}+\frac{1}{D^{\mathrm{4th}}}\right)\right]\\ +\frac{{\rho }_G{Q}_G^{\mathrm{2nd}}}{V_{eff}^{\mathrm{2nd}}{D}^{\mathrm{2nd}}}{\left(D+w_0\right)}^{\mathrm{4th}\left[\frac{\mathrm{2nd}\zeta L_{eff}^{\mathrm{2nd}}}{D^{\mathrm{2nd}}}+\frac{\beta {\mathrm{<figure-callout\; id="0"\; label="w"\; filenames="DE102008050019B4\_0012.png"\; state="\{\{state\}\}">w</figure-callout>}}_0}{\mathrm{4th}}\right]}\end{array}$$

Designations

D Channel width (hydraulic diameter) m F Friction factor for square channels, 28.45 - K ₀ Permeability of a clean wall of a PM filter m ²

$K_0^{\text{'}}$

Permeability of a wall of a PM filter loaded with soot m ² K _s Permeability of the soot layer m ² L _eff Usable length (without plug) of the channels of the PM filter m P _atm Atmospheric pressure N / m ² Q _g Inlet gas flow to the PM filter m ³ / s V _eff Usable volume of the PM filter m w ₀ Wall thickness m w Soot layer thickness m β Forchheimer coefficient for porous wall m ^-1 ζ Expansion / contraction coefficient for inertial pressure loss - µ Gas phase viscosity kg / m / s ρ _g Gas density kg / m ³

It can be assumed that the zones of the PM filter have approximately the same pressure drop. Thus the flow adjusts so that the pressure drop across a clean section is equal to the pressure drop across a loaded section. Equations 1 and 2 can be used to calculate flow when regenerating the zones. The controller can also take temperature differences between the zones into account.

To calculate the energy to be applied to the zones, it can be assumed that the electrical heating device and / or the heating device segments are in a stationary state. The total energy introduced into the electric heater is proportional to the total energy transferred to the gas phase. Thus, the energy is approximately equal to a constant multiplied by the flow rate, furthermore multiplied by the exhaust gas temperature. As the flow increases, the electrical heating device is supplied with more energy for heating the exhaust gas to a predetermined temperature. Conversely, if the flow rate decreases because there is another preferred path for the exhaust gas, namely the cleaned section, a reduced amount of energy is provided for heating the exhaust gas to the same predetermined temperature.

The above-described embodiments reduce the amount of power drawn from a power source, such as a battery, during regeneration of a PM filter. The embodiments reduce the power consumption of an electric heater used to regenerate a particulate filter. The embodiments also improve the durability of the substrate / PM filter because each zone of the PM filter receives the appropriate energy value for regeneration.

The present disclosure tends to improve the regeneration of PM filters. The procedure described here tends to lower the heat delta and therefore improves substrate durability. Force due to thermal expansion and contraction is defined as αΔTE (area), where α is an expansion coefficient, E is the Young's modulus, area is a circumferential surface and is equal to ΠD and ΔT is the temperature delta. As is understood, raising the exhaust temperature before using the electric heaters lowers ΔT, which reduces force due to thermal expansion and contraction. The present disclosure also tends to provide more uniform heating patterns and reduce flame out.

Claims (12)

A system comprising: a particulate filter (34) comprising multiple zones (1, 2, 3, 4, 5); an electric heater (35) comprising a plurality of heater segments (201) each corresponding to a respective one of the zones (1, 2, 3, 4, 5), the electric heater (35) upstream and near the particulate matter filter (34 ) is arranged; and a control module (44) selectively providing a first energy input to a first one of the zones (1, 2, 3, 4, 5) by means of a first one of the heater segments (201) to initiate regeneration in the first zone, the control module (44) selectively provides a second energy input, less than the first energy input, into a second one of the zones (1, 2, 3, 4, 5) by means of a second one of the heater segments (201) to initiate regeneration in the second zone ; characterized in that the plurality of zones (1, 2, 3, 4, 5) are located in a first circumferential zone band and in a second circumferential zone band, the second circumferential zone band surrounding the first circumferential zone band, being within the first circumferential zone band another of the several zones is located. System according to Claim 1 wherein the electrical heater (35) is either adjacent to or in contact with the particulate filter (34). System according to Claim 1 , wherein the control module (44) selectively provides a first energy input by means of the first heater segment (201) for a first period of time and wherein the control module (44) selectively applies a second energy input by means of the second heater segment (201) for a second period of time. System according to Claim 3 , wherein the control module (44) estimates a heater segment temperature of one of the heater segments (201) based on at least one of the power supplied by exhaust gas flow, exhaust gas temperature, and the heater segment (201), and wherein the control module (44) at least one of the energy inputs generated by one of the heater segments (201) is adjusted based on the heater segment temperature. System according to Claim 1 , further comprising: a power source (46); a circuit breaker module that is electrically connected between the power source and the electrical heater (35), the control module (44) selecting one of the heater segments (201) using the circuit breaker module. System according to Claim 5 , wherein the control module (44) generates a pulse width modulated signal, and wherein the circuit breaker module supplies power to the electrical heating device (35) based on the pulse width modulated signal. System according to Claim 1 , wherein the control module (44) generates a first pulse width modulated signal for a first heater segment (201), and wherein the control module (44) generates a second pulse width modulated signal for a second heater segment (201). System according to Claim 1 wherein the control module (44) reduces power supplied to the electrical heater (35) for each subsequent zone regeneration. System according to Claim 1 wherein the control module (44) sequentially triggers regeneration in each of the zones. A method comprising: providing a particulate filter (34) comprising multiple zones (1, 2, 3, 4, 5); Placing an electrical heater (35), comprising a plurality of heater segments (201), each corresponding to a respective one of the zones (1, 2, 3, 4, 5), upstream of and close to the particulate matter filter (34); selectively applying a first energy to a first one of the zones (1, 2, 3, 4, 5) using a first one of the heater segments (201) to initiate regeneration in the first zone and selectively applying a second energy level that is less than that is first energy level at a second one of the zones (1, 2, 3, 4, 5) by means of a second one of the heater segments (201) to trigger regeneration in the second zone; characterized in that the plurality of zones (1, 2, 3, 4, 5) are arranged in a first circumferential zone band and in a second circumferential zone band, the second circumferential zone band surrounding the first circumferential zone band, being within the first circumferential zone band another of the several zones is located. Procedure according to Claim 10 comprising: selectively applying a first energy input using the first heater segment (201) for a first period of time; and selectively applying a second energy input using the second heater segment (201) for a second period of time. Procedure according to Claim 11 , further comprising: estimating a heater segment temperature of one of the heater segments (201) based on at least one power supplied by the exhaust gas flow, exhaust gas temperature and the heater segment (201) and adjusting at least one of the power and duration of an energy input that is provided by means of one of the heater segments (201) , based on the heater segment temperature.

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