DE102009028286A1 - Particulate filter system for filtering particles from exhaust gas of diesel engine of watercraft, has electrical heating element arranged in each gas strand and separately controlled by control unit - Google Patents

Abstract

The system (10) has particle filters (16.1-16.3) for filtering particles from exhaust gas of an internal-combustion engine i.e. diesel engine. A control unit controls regeneration of the particle filters and an auxiliary heating device (14). The particle filters are arranged in partial exhaust gas strands (13.1-13.3). An electrical heating element (14.1) of an electrical auxiliary heating device is arranged in each partial exhaust gas strand in direction of flow of the exhaust gas. The electrical heating element is separately controlled by the control unit. An independent claim is also included for a method for regeneration of particle filters.

Description

The The invention relates to a particulate filter system with particulate filters for filtering particles from the exhaust gas of an internal combustion engine, with an additional electric heater to increase the exhaust gas temperature for the oxidative regeneration of the particulate filters, with an exhaust passage for guiding the exhaust gas and with a Control unit for controlling the regeneration of the particulate filter and the additional heater.

The The invention further relates to a method for the regeneration of Particulate filter of a particulate filter system in the exhaust gas of an internal combustion engine, the exhaust gas temperature upstream of the particulate filters being oxidative Regeneration via an additional electric heater is increased and wherein the regeneration and the additional heater be controlled by a control unit.

State of the art

to Reduction of particulate emissions from diesel engines become particulate filters used in the exhaust passage of internal combustion engines. The duty to Exhaust gas purification extends to road-bound Vehicles such as passenger cars and trucks and also rail-bound Vehicles and watercraft. Great for diesel engines Performance, as used in rail vehicles and watercraft be, this large filter systems are required. The Exhaust gas of the internal combustion engine is through the particulate filter system passed, which deposits the solid particles contained in the exhaust gas and retains in a filter substrate. By the soot embedded in the filter substrate settles Particulate filter system over time, resulting in an increase the exhaust back pressure with a negative effect on engine performance and the fuel consumption noticeable. That's why the stored Russ mass be discharged from time to time. These Filter regeneration occurs during separate regeneration phases an oxidative burning of the particles, the self as an exothermic reaction expires, provided that an exhaust gas temperature of at least 580 ° C and a sufficiently high oxygen concentration in the exhaust gas available. A sufficiently high exhaust gas temperature can via a Adjustment of the operating parameters of the internal combustion engine, via additional burner or via an electric Additional heating in the exhaust duct in the flow direction in front of the Particle filter system can be achieved. About the composition the exhaust gas and the exhaust gas temperature can the course of regeneration to be controlled; In this case, the exhaust gas temperature over the heating power of the additional heating can be influenced.

From the EP 383 187 a regeneration system for a diesel particulate filter is known in which the particle filter is electrically heated to a predetermined ignition temperature of the deposited particles. In this case, the heating rate is monitored within the filter with the aid of a temperature sensor and, if necessary, an air stream is supplied to the exhaust gas for cooling the filter.

The electric auxiliary heating of the exhaust gas for the regeneration of particulate filters offers a number of advantages, including that of a simple control strategy and a cost-effective and space-saving implementation. A disadvantage of the electric heating of the exhaust gas is that often not enough electrical energy available stands for the regeneration of the particulate filter reach required exhaust gas temperature.

From the DE 101 42 804 an exhaust gas purification system for purifying the exhaust gas of an internal combustion engine with an exhaust aftertreatment unit is known, which is characterized in that at least one adjustable flow divider is provided by means of which in a position for the regeneration of the exhaust aftertreatment unit, a first partial flow of the exhaust gas can be generated, which flows through the exhaust aftertreatment unit, wherein a remaining second partial flow flows through at least one further exhaust gas aftertreatment unit. The claimed arrangement, however, requires moving parts in order to be able to regenerate the exhaust aftertreatment unit designed as a particle filter, which leads to a greater susceptibility to error and to high costs for the system.

To reduce the temperature required for regeneration, the surface of the particulate filter may be catalytically coated. The regeneration of a particulate filter can be started when exceeding a predetermined limit value for the exhaust back pressure. The regeneration can also be carried out continuously, if a sufficiently high exhaust gas temperature in the range of 350 to 500 ° C and a sufficient oxygen content, for example from a sufficiently high proportion of NO ₂ , are present in the exhaust gas. The continuous regeneration of particulate filters is known as CRT (continuous regeneration trap).

It The object of the invention is to provide a particle filter system, the electric heating of the exhaust gas on the for the particulate filter regeneration requires exhaust gas temperature allows.

It It is a further object of the invention to provide a method for operating the To provide particulate filter system.

Disclosure of the invention

The The object of the invention relating to the device is solved by that the exhaust gas of the internal combustion engine in the particulate filter system at least partially guided in parallel Teilabgassträngen is that arranged in each Teilabgasstrang a particulate filter is and that in each sub exhaust line in the flow direction of the exhaust gas in front of the particulate filter separately from the control unit controllable electric heating element of the additional electric heater is arranged. Due to the separately controllable electrical heating elements The auxiliary heater can be used for any particulate filter individually raised the exhaust gas temperature before the particulate filter so far be that the burning of soot particles begins. The typically available in a locomotive application or a watercraft Although electrical power is not enough to a sufficient Raising the temperature of the entire exhaust stream, but sufficient for sufficient heating of the guided in a partial exhaust gas line Partial exhaust stream out. The existing in the vehicle electrical Power can thus replace an additional burner heat the exhaust gas and the fuel for the burner save on. Likewise, a fuel metering is unnecessary in front of the particulate filter to generate heat by combustion of hydrocarbons. By eliminating the addition can a required mixing section omitted, which the design of the system becomes more compact. The division of the particle filter system in single particle filter improves along with the electric Heating the exhaust gas the homogeneity of the temperature distribution in the particle filter during burning of the particles.

Corresponding a preferred embodiment variant of the invention can be provided that in each sub exhaust line before the particulate filter and after the Particle filter in each case a pressure sensor is arranged or that in at least a Teilabgasstrang before the particulate filter and after the particle filter is arranged in each case a pressure sensor and that the pressure sensors are connected to the control unit. Is before and after each particulate filter provided a pressure sensor, so can the load of each particulate filter from the differential pressure over determines the particular particle filter and regeneration if necessary of the particulate filter started and stopped. Are against with only one particle filter or part of the particle filter pressure sensors provided, the loading state of this particulate filter can be determined and their regeneration needs are determined. Not with pressure sensors provided particulate filter can then according to a predetermined sequence depending on the regeneration request regenerated for a monitored with pressure sensors particulate filter become. By so saved pressure sensors can the costs for the particulate filter system are lowered.

to Performing the regeneration of a particulate filter can in the control unit, a first program sequence for separate control the electrical heating elements as a function of the signals the pressure sensors and / or provided according to a time specification be.

A fast regeneration with simultaneous protection of the particle filter system Thermal overload can be achieved by in each partial exhaust after electric heating and before the particle filter, a temperature sensor is provided with the the control unit is connected, and in the control unit a second program sequence for control and monitoring the temperature of the exhaust gas after electric heating and before the particulate filter is provided.

If a diesel oxidation catalyst is provided in the exhaust duct upstream of the partial exhaust gas strands, the NO ₂ produced in this way can be used for continuous regeneration (CRT effect) of the particulate filter system, with the exhaust gas temperature being raised to a temperature of 300 ° C. with the aid of the additional electric heater and the associated heating elements is increased before the particulate filters.

The The object of the invention relating to the method is solved by that the particulate filters on separate Teilabgasstränge Exhaust gas is supplied to the internal combustion engine and that to Regeneration of a particulate filter the exhaust gas temperature of each Teilabgasstrang in the flow direction of the exhaust gas in front of the Particle filters arranged and controlled separately by the control unit electrical Heating elements of the additional electric heater increases becomes. The process allows only so many particulate filters be regenerated at the same time that the available electrical energy for heating the partial exhaust gas stream in the partial exhaust line on the necessary regeneration temperature is sufficient. The operation of the internal combustion engine and the operation of the vehicle driven thereby are by the Procedure does not affect, since only part of the Plant is regenerated. As always only a single or a small number be regenerated by particulate filters, is the energy input in the system comparatively low. The rule strategy is through the division of the particle filter system into individual particle filters simplified, so that in a simple way a controlled thermal Regeneration achieved for each individual particle filter can be.

The maximum available for the heating of the exhaust gas electric heating power is by the available electrical energy, as beispielswei se generated by a driven by the internal combustion engine generator is limited. In order to achieve a sufficient exhaust gas temperature for the regeneration of the particulate filter by the electrical additional heating of the exhaust gas, it can be provided that only one particulate filter or a predetermined proportion of the particulate filter is regenerated at a time.

Becomes the loading state of the particulate filter by a differential pressure measurement via the respective particle filter is detected and takes place at a predetermined Maximum load of a particulate filter regeneration by a Increase of the exhaust gas temperature by the heating element in the respective partial exhaust, it can be achieved that only the particulate filter be regenerated, which reaches a predetermined maximum load to have.

A particularly simple regeneration strategy envisages that during a regeneration cycle all particulate filters in a given Sequence can be regenerated one after the other. This way you can be achieved that always enough filter capacity is ready.

A on the one hand fast regeneration and on the other hand more effective Protection of the particle filter against damage can be achieved be done by during the regeneration of a particulate filter the temperature of the particulate filter is monitored and when exceeded a predetermined temperature or a predetermined temperature rise the heating power of the electric heating element in the Teilabgasstrang is reduced before the particulate filter.

One Effective burning of the particles in a particle filter can be achieved be by the regeneration of a particulate filter by the additional electric Heating the exhaust gas in the Teilabgasstrang before the particulate filter to a temperature above 580 ° C, preferably over 620 ° C, is started.

If there is a sufficient amount of NO ₂ in the exhaust gas, for example by a diesel oxidation catalytic converter arranged in front of the particle filter, all heating elements can be controlled in such a way that the temperature of the exhaust gas in the partial exhaust gas lines upstream of the particle filters is at least 300 ° C. The regeneration then takes place continuously for all particle filters simultaneously.

Prefers be the method or apparatus for the regeneration of particulate filters a particulate filter system in the exhaust duct one with diesel fuel operated locomotive or one powered by diesel fuel Watercraft applied. In such vehicles is for other applications have sufficient electrical power available, too to start the regeneration of a particulate filter in a Teilabgasstrang can be used.

Short description of the drawing

The Invention will be described below with reference to one shown in the figure Embodiment explained in more detail. It shows:

1 a schematically a particulate filter system for filtering particles from the exhaust gas of an internal combustion engine.

1 schematically shows a particulate filter system 10 for filtering particles from the exhaust gas of an internal combustion engine, not shown. The exhaust gas of the internal combustion engine is the particulate filter system 10 in the direction of the arrows shown via an exhaust duct 11 and a diesel oxidation catalyst 12 fed. After the diesel oxidation catalyst 12 becomes the exhaust duct 11 in three partial exhaust gas trains 13.1 . 13.2 . 13.3 divided up. Three electrical heating elements 14.1 . 14.2 . 14.3 an electric auxiliary heater 14 are the three partial exhaust gas strands 13.1 . 13.2 . 13.3 assigned. The electric heating elements 14.1 . 14.2 . 14.3 each follow a temperature sensor 15.1 . 15.2 . 15.3 and a particle filter 16.1 . 16.2 . 16.3 , Subsequently, the three partial exhaust strands 13.1 . 13.2 . 13.3 reunited as an exhaust duct 11 continued. In the exhaust duct 11 follow in the exhaust direction, a metering unit 17 , a static mixer 18 and an SCR catalyst 19 ,

The diesel oxidation catalyst 12 serves to reduce the emission of unburned hydrocarbons and carbon monoxide. After the exhaust gas of the internal combustion engine, the diesel oxidation catalyst 12 has passed through, it is in the embodiment shown on the three partial exhaust gas lines 13.1 . 13.2 . 13.3 split and the additional electric heater 14 the particle filters 16.1 . 16.2 . 16.3 fed. According to the present invention, the particulate filter system 10 Any number of parallel partial exhaust gas strands arranged in parallel 13.1 . 13.2 . 13.3 with the associated electrical heating elements 14.1 . 14.2 . 14.3 , Temperature sensors 15.1 . 15.2 . 15.3 and particle filters 16.1 . 16.2 . 16.3 exhibit. In the particle filters 16.1 . 16.2 . 16.3 Soot particles are filtered out of the exhaust gas and stored. In the reunited exhaust duct 11 is the exhaust gas at the dosing unit 17 fed to a urea-water solution. By a chemical reduction in the subsequent SCR catalyst so nitrogen oxides (NOx) can be reduced to nitrogen.

The particle filter 16.1 . 16.2 . 16.3 must be regenerated from time to time to the stored Remove soot particles. A known method for the regeneration of particulate filters 16.1 . 16.2 . 16.3 is the oxidative conversion of the embedded particles. For this purpose, the exhaust gas temperature is increased so much that the combustion of the particles starts. The necessary exhaust gas temperature is about 580 ° C, preferably 620 ° C. The combustion itself is exothermic. Various methods and devices are known for increasing the exhaust gas temperature. In the present embodiment, the exhaust gas temperature by the additional electric heater 14 with the associated heating elements 14.1 . 14.2 . 14.3 increased to the necessary temperature.

When a loading of the particle filter 16.1 . 16.2 . 16.3 is present, which makes a regeneration necessary, can via a differential pressure measurement via the particulate filter 16.1 . 16.2 . 16.3 be determined from an assigned map. These are before and after the particulate filters 16.1 . 16.2 . 16.3 not shown pressure sensors attached, which are connected to a control unit, also not shown.

In order to achieve the necessary increase in temperature of the exhaust gas, a sufficient amount of electrical energy must be provided. In order to heat up the entire exhaust gas flow sufficiently, the available electrical energy is not sufficient in many internal combustion engines. According to the invention, the exhaust gas flow is therefore on the partial exhaust gas strands 13.1 . 13.2 . 13.3 split and the individual particle filters 16.1 . 16.2 . 16.3 fed. Now by the control unit on the basis of differential pressure measurement, for example via the first particle filter 16.1 determined that this must be regenerated, so the control unit is the associated heating element 14.1 the additional electric heater 14 driven. So it will only be the one in the first Teilabgasstrang 13.1 guided partial exhaust gas flow so far heated that the regeneration of the first particulate filter 16.1 starts. In this case, the exhaust gas temperature using the first temperature sensor 15.1 supervised. The other two particle filters 16.2 . 16.3 will continue to be operated regularly in the collecting operation. Since only a portion of the exhaust gas must be heated, the required electrical power is much lower than that required to heat the entire exhaust stream and can for example be provided by a generator driven by the internal combustion engine.

Upon completion of the regeneration of the first particulate filter 16.1 may be the regeneration of the second particulate filter 16.2 and then the third particulate filter 16.3 by a respective increase in the temperature of the exhaust gas with the aid of the second heating element 14.2 and the third heating element 14.3 be performed.

The sequence, like the particle filter 16.1 . 16.2 . 16.3 can be regenerated, can be specified. So it is possible that when a regeneration request for a particulate filter 16.1 . 16.2 . 16.3 then the remaining particle filters 16.1 . 16.2 . 16.3 be regenerated. Alternatively, it may be provided that the individual particle filters 16.1 . 16.2 . 16.3 then regenerated when over the respective particulate filter 16.1 . 16.2 . 16.3 a corresponding differential pressure is present. In this case, a program sequence can be stored in the control unit, which prevents multiple particulate filter 16.1 . 16.2 . 16.3 be regenerated at the same time, so that sufficient electrical energy is available for regeneration.

The advantage here is that for the heating of the exhaust gas for the regeneration of the particulate filter 16.1 . 16.2 . 16.3 used electrical energy and can be dispensed with the otherwise necessary use of a burner or a fuel metering. Due to the partial regeneration of the particle filter 16.1 . 16.2 . 16.3 the electrical energy requirement is low. The process can be implemented with a simple control strategy, providing a controlled thermal regeneration for each individual particle filter 16.1 . 16.2 . 16.3 is possible. During the regeneration can be achieved by the electric heating of the exhaust gas, a homogeneous temperature distribution with correspondingly lower thermal stress of the filter material. Since no HC mixing lines are needed, a compact design is possible. Through the successive regeneration of the particle filter 16.1 . 16.2 . 16.3 the energy input into the system is low. A further advantage is that there is no impairment of the operation of the internal combustion engine.

The described particulate filter system 10 also allows the continuous regeneration of the particulate filter 16.1 . 16.2 . 16.3 via the CRT effect (CRT: continuous regeneration trap). For this purpose, the exhaust gas temperature before the particulate filters 16.1 . 16.2 . 16.3 increased by controlling all heating elements to at least 300 ° C. The prerequisite for the continuous regeneration is a sufficient amount of NO ₂ in the exhaust gas, which through the upstream Dieseloxidationskatalysator 12 provided.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 383187 [0004]
• - DE 10142804 [0006]

Claims (13)

Particulate filter system ( 10 ) with particle filters ( 16.1 . 16.2 . 16.3 ) for filtering particles from the exhaust gas of an internal combustion engine, with an additional electric heater ( 14 ) for increasing the exhaust gas temperature for oxidative regeneration of the particulate filter ( 16.1 . 16.2 . 16.3 ), with an exhaust duct ( 11 ) for guiding the exhaust gas and with a control unit for controlling the regeneration of the particulate filters ( 16.1 . 16.2 . 16.3 ) and the additional heater ( 14 ), characterized in that the exhaust gas of the internal combustion engine in the particulate filter system ( 10 ) at least partially in parallel partial exhaust gas strands ( 13.1 . 13.2 . 13.3 ), that in each partial exhaust gas line ( 13.1 . 13.2 . 13.3 ) a particle filter ( 16.1 . 16.2 . 16.3 ) and that in each partial exhaust line ( 13.1 . 13.2 . 13.3 ) in the flow direction of the exhaust gas in front of the particle filter ( 16.1 . 16.2 . 16.3 ) an electrically controllable by the control unit electric heating element ( 14.1 . 14.2 . 14.3 ) of the additional electric heater ( 14 ) is arranged. Particulate filter system ( 10 ) according to claim 1, characterized in that in each partial exhaust line ( 13.1 . 13.2 . 13.3 ) in front of the particle filter ( 16.1 . 16.2 . 16.3 ) and after the particle filter ( 16.1 . 16.2 . 16.3 ) in each case a pressure sensor is arranged or that in at least one partial exhaust gas line ( 13.1 . 13.2 . 13.3 ) in front of the particle filter ( 16.1 . 16.2 . 16.3 ) and after the particle filter ( 16.1 . 16.2 . 16.3 ) A pressure sensor is arranged in each case and that the pressure sensors are connected to the control unit. Particulate filter system ( 10 ) according to claim 1 or 2, characterized in that in the control unit, a first program sequence for the separate control of the electric heating elements ( 14.1 . 14.2 . 14.3 ) is provided as a function of the signals of the pressure sensors and / or according to a time specification. Particulate filter system ( 10 ) according to one of claims 1 to 3, characterized in that in each partial exhaust line ( 13.1 . 13.2 . 13.3 ) after electric heating and before the particle filter ( 16.1 . 16.2 . 16.3 ) a temperature sensor ( 15.1 . 15.2 . 15.3 ) is provided, which is connected to the control unit, and that in the control unit, a second program sequence for controlling and monitoring the temperature of the exhaust gas after the electric heating and before the particulate filter ( 16.1 . 16.2 . 16.3 ) is provided. Particulate filter system ( 10 ) according to one of claims 1 to 4, characterized in that in the exhaust gas passage in front of the partial exhaust gas strands ( 13.1 . 13.2 . 13.3 ) a diesel oxidation catalyst ( 12 ) is provided. Process for the regeneration of particulate filters ( 16.1 . 16.2 . 16.3 ) a particulate filter system ( 10 ) in the exhaust gas of an internal combustion engine, wherein the exhaust gas temperature before the particulate filters ( 16.1 . 16.2 . 16.3 ) for oxidative regeneration via an additional electric heater ( 14 ) and wherein the regeneration and the auxiliary heating device ( 14 ) are controlled by a control unit, characterized in that the particulate filters ( 16.1 . 16.2 . 16.3 ) via separate partial exhaust gas strands ( 13.1 . 13.2 . 13.3 ) Exhaust gas of the internal combustion engine is supplied and that for the regeneration of a particulate filter ( 16.1 . 16.2 . 16.3 ) the exhaust gas temperature of each partial exhaust line ( 13.1 . 13.2 . 13.3 ) in the flow direction of the exhaust gas before the particulate filters ( 16.1 . 16.2 . 16.3 ) and separately controllable by the control unit electrical heating elements ( 14.1 . 14.2 . 14.3 ) of the additional electric heater ( 14 ) is increased. A method according to claim 6, characterized in that at a time only a particulate filter ( 16.1 . 16.2 . 16.3 ) or a predetermined proportion of the particulate filters ( 16.1 . 16.2 . 16.3 ) is regenerated. A method according to claim 6 or 7, characterized in that the loading state of the particulate filter ( 16.1 . 16.2 . 16.3 ) by a differential pressure measurement over the respective particle filter ( 16.1 . 16.2 . 16.3 ) is detected and that at a predetermined maximum load of a particulate filter ( 16.1 . 16.2 . 16.3 ) the regeneration by an increase of the exhaust gas temperature by the heating element ( 14.1 . 14.2 . 14.3 ) in the respective partial exhaust gas line ( 13.1 . 13.2 . 13.3 ) he follows. Method according to one of claims 6 to 8, characterized in that during a regeneration cycle all particulate filters ( 16.1 . 16.2 . 16.3 ) are regenerated sequentially in a predetermined order. Method according to one of claims 6 to 9, characterized in that during the regeneration of a particulate filter ( 16.1 . 16.2 . 16.3 ) the temperature of the particulate filter ( 16.1 . 16.2 . 16.3 ) is monitored and the exceeding of a predetermined temperature or a predetermined temperature rise, the heating power of the electric heating element in the partial exhaust gas line ( 13.1 . 13.2 . 13.3 ) in front of the particle filter ( 16.1 . 16.2 . 16.3 ) is reduced. Method according to one of claims 6 to 10, characterized in that the regeneration of a particulate filter ( 16.1 . 16.2 . 16.3 ) by the additional electric heating of the exhaust gas in the partial exhaust line ( 13.1 . 13.2 . 13.3 ) in front of the particle filter ( 16.1 . 16.2 . 16.3 ) is started at a temperature above 580 ° C, preferably above 620 ° C. A method according to claim 6, characterized in that for the continuous regeneration of the particulate filter ( 16.1 . 16.2 . 16.3 ) all heating elements ( 14.1 . 14.2 . 14.3 ) are controlled such that the temperature of the exhaust gas in the partial exhaust gas strands ( 13.1 . 13.2 . 13.3 ) in front of the particle filters ( 16.1 . 16.2 . 16.3 ) is at least 300 ° C. Application of the method or the device according to one of the preceding claims for the regeneration of particulate filters ( 16.1 . 16.2 . 16.3 ) a particulate filter system ( 10 ) in the exhaust passage of a diesel fueled locomotive or a diesel fueled watercraft.

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