DE102005032457A1 - Method and device for controlling or controlling the Rußabbrandgeschwindigkeit - Google Patents

Abstract

The invention relates to a method for controlling or regulating the introduction of fuel into an exhaust gas duct of an internal combustion engine in front of a catalytic converter or particle filter, wherein a measuring device monitors whether fuel has already ignited in the exhaust gas duct before the catalytic converter or the particle filter. DOLLAR A The invention further relates to a device for controlling or regulating the soot burn-off speed in an internal combustion engine with an engine block, an exhaust gas duct with a catalytic converter and a downstream particle filter, a fuel metering unit for direct injection of the fuel into the exhaust gas duct being provided in front of the catalytic converter, with a Temperature sensor, the temperature in the exhaust gas duct upstream of the catalytic converter and with a temperature sensor the temperature in the exhaust gas ducting downstream of the catalytic converter can be determined, and fuel combustion in front of the catalytic converter can be detected from the respective temperature rise. DOLLAR A With the described method and the device, monitoring of an uncontrolled fuel combustion upstream of the catalytic converter can be implemented, which ensures a more precise temperature profile upstream of the particle filter and optimizes the soot burning rate for regeneration of the particle filter.

Description

The The invention relates to a method for controlling or regulating the Introducing fuel into an exhaust system of an internal combustion engine in front of a catalyst or particle filter.

The The invention further relates to a device for controlling or Control of Rußabbrandgeschwindigkeit in an internal combustion engine with an engine block, an exhaust system with a catalyst and a downstream particulate filter, wherein in front of the catalyst a fuel metering unit for direct injection of the fuel in the exhaust system is provided.

Become frequent Internal combustion engines, in particular diesel internal combustion engines with Exhaust after-treatment systems equipped, in particular a particulate soot filter or Diesel Particulate Filter (DPF). For the regeneration of the diesel particulate filter are temperatures above the usual exhaust gas temperatures necessary. Without additional measures Oxidize the particles at about 550 to 600 ° C. By combining the particle soot filter with an oxidation catalyst (OXI-KAT), by catalytic coating the filter and / or by an additive addition can be the lower temperature threshold for the Oxidation to approx. 250 to 350 ° C Lower.

In certain operating conditions the internal combustion engine may be the case that the regeneration uncontrolled fast or too slow. Especially with a Uncontrolled rapid burnup may be due to the highly exothermic Oxidation of the particles come to an undesirable heat release, the with steep, wandering temperature fronts in the filter and very high temperatures accompanied. Such states should be safely avoided or, if appropriate, appropriate activities controlled and controlled. Is regeneration too slow? from, must the regeneration measures be maintained for too long, resulting in increased fuel consumption Episode has. In addition, there is a risk that the operation of the internal combustion engine is interrupted or transferred to an operating state, the abort forces regeneration.

to Avoidance of such conditions is in DE-OS 10333441 A1 a method and an apparatus for controlling an exhaust aftertreatment system, in particular one Particle filter, described an internal combustion engine. It is a setpoint (LAS) for a lambda signal (L) or a change a lambda signal (L) can be specified. An actual value for the lambda signal (L) or for the change of the lambda signal (L) is detected. Starting from the comparison between the actual value and the setpoint (LAS) becomes a control signal for an actuating element, with which the reaction in the exhaust aftertreatment system is controllable, predetermined such that the actual value approaches the target value (LAS). With The control elements can affect the amount of oxygen in the exhaust gas become. As adjusting elements can a Exhaust gas recirculation valve, a throttle valve, adjusting elements for influencing an exhaust gas turbocharger and / or a fuel metering system, which is a post-injection of a Fuel in the internal combustion engine makes.

In Scripture EP 1364110 B1 a further method and a corresponding device is described in which a parameter is determined as a function of at least one operating characteristic of the internal combustion engine and at least one operating characteristic of the particle filter for controlling a regeneration process, which characterizes a future intensity of a reaction in the particle filter. When a threshold value is exceeded by the parameter, at least one measure is taken which reduces the oxygen concentration in the exhaust gas of the internal combustion engine, with the aim that the parameter does not reach the threshold value.

Reached the particle soot filter a certain load and is a regeneration of the filter because of the engine operating state is not guaranteed, so is after the State of the art provided that the exhaust gas temperature is increased so far, that the particles burn quickly. This is the concentration increased in hydrocarbons in the exhaust gas, which then in an oxidation catalyst be implemented and lead to a temperature increase. The concentration increase in Exhaust line is usually through a post-injection in the fuel metering system on the engine block or by a direct metering of diesel fuel into the exhaust system, wherein the dosage is normally specified depending on operating point.

If Diesel fuel is injected directly into the exhaust system, so All known methods assume that this in the catalyst is implemented. Measurements show, however, that a flaming of the injected Fuel quantity is possible even before the catalyst. This is special then the case, if the injection at least partially already in the exhaust manifold he follows. A combustion in front of the catalyst, however, leads to the deposit Models and their derived controllers are faulty can lead to significant deviations from the ideal state.

in the With regard to avoiding this combustion in front of the catalyst, It is an object of the invention to provide a method for controlling or regulating the Rußabbrandgeschwindigkeit to provide this type of combustion diagnosed on the one hand and on the other hand, if this condition occurs, is more appropriate Way to respond.

It Another object of the invention is a device for controlling or control of Rußabbrandgeschwindigkeit provide.

Advantages of invention

The The object relating to the method is achieved in that monitored by a measuring device whether fuel is already in the exhaust system before the catalyst or ignited the particle filter Has. This has the advantage of having a fuel ignition system the catalyst can be reliably detected. When a Fuel inflammation before the catalyst can appropriate measures, depending on the operating state of the internal combustion engine, be initiated which allow optimal control or regulation of Rußabbrandgeschwindigkeit.

Becomes The supervision with at least one, in the flow direction performed the exhaust gas upstream of the catalyst temperature sensor can a rise in temperature upstream of the catalyst can be detected when hydrocarbons burn in front of the catalyst. In this case, then the Dosiermenge be increased in the catalyst compared to a pure combustion, around the raised heat loss compensate.

In preferred embodiment becomes the surveillance by comparing the measured temperature rise above the Catalyst with a temperature increase calculated in a model carried out. It can also complex relationships, which are dependent on a large number of influencing factors become.

When preferred application of the method is provided that with a Temperature sensor the temperature in the exhaust system upstream of the catalyst and with another temperature sensor, the temperature in the exhaust system after measured from the catalyst and from the respective temperature rise a fuel combustion is detected in front of the catalyst. From the temperature gradients can the Abbrandfront detected and depending on the course corresponding activities be taken. This improves the control of the Rußabbrandgeschwindigkeit when regenerating the particulate filter.

in the In view of modern diesel internal combustion engines is in preferred embodiment in the exhaust system in front of the temperature sensor and the catalyst an exhaust gas turbocharger arranged, wherein the fuel combustion in the exhaust system before the Exhaust gas turbocharger and / or the catalyst is detected.

In preferred embodiment is the fuel combustion in front of the exhaust gas turbocharger and / or in front of the catalyst from the course of the with the temperature sensor measured temperature and the comparison with a previously stored operating point-dependent temperature profile, which determines without direct injection of the fuel into the exhaust system was detected. This is an operating state-dependent control or control of Rußabbrandgeschwindigkeit during the regeneration process of the particulate filter possible.

In Another preferred embodiment is fuel combustion in front of the exhaust gas turbocharger and / or in front of the catalyst from the real one Temperature rise over considering the catalyst an additional one Tolerance and a comparison of this value with one in a model calculated temperature rise over the Catalyst detected. Short-term temperature fluctuations or Tolerance deviations in the temperature sensors are at the expansion considered accordingly.

is the temperature in front of the exhaust gas turbocharger may be too high Fuel combustion in front of the exhaust gas turbocharger and / or in front of the catalyst the metered addition of the fuel with the fuel metering unit stopped or reduced. This prevents overheating the exhaust gas turbocharger and protects this from harm.

is however, the temperature is too low and thus optimal regeneration the particle filter is not guaranteed, can at a detected fuel combustion in front of the exhaust gas turbocharger and / or before the catalyst, the metered addition of the fuel the fuel metering unit increases become. With that you can for example higher heat loss be compensated.

A particularly exact metering, especially with an increase in the Metering can be achieved if the relative increase in operating point dependent in a characteristic unit of a control unit is deposited. In order to can For example, the various operating conditions of the internal combustion engine considered and thus an optimal regeneration temperature for the particle filter be controlled.

Alternatively, if you increase the zudo the relative increase can be calculated by a turbocharger and / or exhaust pipe model. Thus, flow models can be used to optimize Rußabbrandgeschwindigkeit, which contribute to improving the control or the scheme.

in the With regard to a more precise overall control of the internal combustion engine can the running to control the internal combustion engine models accordingly the additional heat source in front of the exhaust gas turbocharger and as a result of combustion before Catalyst reduced flow be corrected by fuel in the catalyst. This improves the simulation models in the engine control, for example also the plausibilizations of the different temperature sensors based on it or drag models be improved.

to support Can the addition of fuel to achieve optimal Regeneration temperature with a post-injection on a fuel metering system be set on the engine block.

The the object relating to the device is achieved in that with a temperature sensor, the temperature in the exhaust system before the catalyst and with a temperature sensor, the temperature in the exhaust system is determined by the catalyst and from the respective temperature rise a fuel combustion upstream of the catalyst is detectable. This can cause a temperature increase be detected before the catalyst and also before the particulate filter and thus a fuel combustion detected before the catalyst become.

ever according to the operating state of the engine can then be made appropriate control intervention be when the temperature sensors using signal lines with a control unit for controlling the metered addition of fuel are connected and the control unit by means of a signal line connected to the fuel metering unit.

is the control unit by means of a signal line with a fuel metering system connected to the engine block, may additionally or alternatively to the metering of fuel by means of the fuel metering unit a post-injection with the fuel metering system on the engine block.

has the control unit on at least one Kennfeldeinheit, the Metered addition of the fuel into the exhaust system operating point-dependent, although other engine parameters can be taken into account.

In Turbocharged internal combustion engines is in the exhaust system before arranged an exhaust gas turbocharger the temperature sensor and the catalyst, whereby the performance of the internal combustion engine can be significantly increased can.

To the Protection of exhaust gas turbocharger against overheating it is provided that the control unit by means of a signal line with a further temperature sensor in the exhaust system before is connected to the exhaust gas turbocharger. This is at a fuel burn in the exhaust manifold at the engine block of importance, since in this case extremely high temperatures on Exhaust gas turbocharger may arise.

In preferred embodiment may be the function of the control unit as software and / or hardware accomplished be and at least partially be part of a higher-level engine control, wherein a program stored function for the control or regulation the Rußabbrandgeschwindigkeit particularly simple as a subroutine can be integrated throughout the engine control software. this makes possible also inexpensive Software updates.

drawing

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

1 a schematic representation of an apparatus for controlling or regulating the Rußabbrandgeschwindigkeit in an internal combustion engine.

description the embodiments

1 schematically shows the main components of an internal combustion engine 1 with an engine block 10 , an exhaust system 20 with a catalyst 40 and a downstream particle filter 50 , In the embodiment shown, the internal combustion engine 1 additionally in the exhaust system 20 in front of the catalyst 40 an exhaust gas turbocharger 30 on. In front of the catalyst 40 is a fuel metering unit 60 for direct injection of the fuel into the exhaust system 20 intended. The fuel metering device 60 can be a pump 63 and / or a valve 62 to accurately meter the fuel.

This arrangement corresponds in particular schematically to the structure of a diesel engine driven internal combustion engine 1 in which it is provided that with the fuel metering device 60 Diesel fuel can be introduced into the exhaust system.

According to the invention, it is provided in this device that for controlling or regulating the Rußabbrandgeschwindigkeit with a temperature sensor 80 the temperature in the exhaust system 20 in front of the catalyst 40 and with a temperature sensor 90 the temperature in the exhaust system 20 after the catalyst 40 can be determined and from the respective increase in temperature fuel combustion before the front of the catalyst 40 is detectable. The temperature sensors 80 . 90 are by means of signal lines 81 . 91 with a control unit 100 connected to control the metered addition of fuel.

The control unit 100 is by means of a signal line 64 with the fuel metering unit 60 connected. In addition, it is provided in the device shown that the control unit 100 by means of a signal line 12 with a fuel metering system 11 on the engine block 10 connected is. Furthermore, in the example shown, the control unit 100 by means of a signal line 71 with another temperature sensor 70 in the exhaust system 20 in front of the turbocharger 30 connected.

In an inventive embodiment it is provided that the function of the control unit 100 designed to control or regulate Rußabbrandgeschwindigkeit as software and / or hardware and at least partially may be part of a higher-level engine control. In this case, the control unit 100 at least one characteristic unit 101 on in the metered addition of the fuel into the exhaust system 20 Operating point dependent is deposited.

With the device described above can with the temperature sensor 80 the temperature in the exhaust system 20 in front of the catalyst 40 and with a temperature sensor 90 the temperature in the exhaust system 20 after the catalyst 40 measured and from the respective increase in temperature fuel combustion in front of the exhaust gas turbocharger 30 and / or the catalyst 40 be detected. The fuel combustion in front of the turbocharger 30 and / or in front of the catalyst 40 on the one hand from the course of the with the temperature sensor 80 measured temperature and the comparison with a previously stored operating point-dependent temperature profile, which without direct injection of the fuel into the exhaust system 20 was detected, detected. If the temperature upstream of the catalyst is higher than the previously stored temperature profile, fuel combustion is located in front of the exhaust gas turbocharger 30 and / or in front of the catalyst 40 in front. In addition, the detection can be improved by an exhaust gas temperature model.

Another method provides that the fuel combustion in front of the exhaust gas turbocharger 30 and / or in front of the catalyst 40 from the real temperature rise over the catalyst 40 taking into account additional tolerance and comparing this value with a temperature increase across the catalyst calculated in a model 40 is detected.

In response to detected fuel combustion in front of the exhaust gas turbocharger 30 and / or in front of the catalyst 40 can the metered addition of the fuel with the fuel metering unit 60 stopped or reduced when, for example, the temperature in front of the turbocharger 30 is too high. Overheating of the exhaust gas turbocharger 30 can do this with the additional temperature sensor 70 be monitored.

Depending on the configuration of the exhaust system 20 and the arrangement of the catalyst 40 and the particulate filter 50 can be provided at other locations more temperature sensors.

If the temperature for regeneration of the particulate filter is too low, on the other hand, at a detected fuel combustion in front of the exhaust gas turbocharger 30 and / or in front of the catalyst 40 the metered addition of the fuel with the fuel metering unit 60 be increased, with an increase in the addition of the relative increase operating point-dependent in the unit of field 101 the control unit 100 can be deposited. The relative increase may also be calculated by a turbocharger and / or exhaust pipe model. With regard to the overall control of the internal combustion engine can be provided that for controlling the internal combustion engine 1 accompanying models according to the additional heat source in front of the turbocharger 30 and as a result of combustion in front of the catalyst 40 reduced flow of fuel into the catalyst 40 Getting corrected. An additional metering of fuel to achieve an optimum regeneration temperature may be achieved with a post-injection on the fuel metering system 11 on the engine block 10 get supported.

With the described method and apparatus, monitoring of uncontrolled fuel combustion upstream of the catalyst may be provided 40 be realized, resulting in a more accurate temperature profile in front of the particle filter 50 ensures and the Rußabbrandgeschwindigkeit for the regeneration of the particulate filter 50 optimized. At the same time, an overheating protection for the exhaust gas turbocharger 30 provided. In addition, the simulation models can be improved within the engine control.

In principle, it is conceivable that the described device and the method also in other concepts for an internal combustion engine 1 , in heat-power machines or Heizungsan be used in which for the regeneration of particulate filters 50 Targeted soot combustion is required.

Claims (20)

Method for controlling or regulating the introduction of fuel into an exhaust system ( 20 ) an internal combustion engine ( 1 ) in front of a catalyst ( 40 ) or particle filter ( 50 ), characterized in that is monitored by means of a measuring device, whether fuel is already in the exhaust system ( 20 ) in front of the catalyst ( 40 ) or the particle filter ( 50 ) has ignited. A method according to claim 1, characterized in that the monitoring with at least one, in the flow direction of the exhaust gas in front of the catalyst ( 40 ) arranged temperature sensor ( 80 ) is carried out. A method according to claim 1 or 2, characterized in that the monitoring by comparing the measured temperature rise above the catalyst ( 40 ) is performed with a temperature increase calculated in a model. Application of the method according to one of the preceding claims for controlling or regulating the Rußabbrandgeschwindigkeit in an internal combustion engine ( 1 ) with an engine block ( 10 ), an exhaust system ( 20 ) with a catalyst ( 40 ) and a downstream particle filter ( 50 ), whereby in front of the catalyst ( 40 ) a fuel metering unit ( 60 ) for the direct injection of the fuel into the exhaust system ( 20 ) is provided, characterized in that with a temperature sensor ( 80 ) the temperature in the exhaust system ( 20 ) in front of the catalyst ( 40 ) and with a temperature sensor ( 90 ) the temperature in the exhaust system ( 20 ) after the catalyst ( 40 ) and from the respective temperature rise, a fuel combustion upstream of the catalyst ( 40 ) is detected. Use according to claim 4, characterized in that in the exhaust system ( 20 ) in front of the temperature sensor ( 80 ) and the catalyst ( 40 ) an exhaust gas turbocharger ( 30 ) is arranged and the fuel combustion in the exhaust system ( 20 ) in front of the exhaust gas turbocharger ( 30 ) and / or the catalyst ( 40 ) is detected. Application according to claim 4 or 5, characterized in that the fuel combustion in front of the exhaust gas turbocharger ( 30 ) and / or in front of the catalyst ( 40 ) from the course of the with the temperature sensor ( 80 ) measured temperature and the comparison with a previously stored operating point-dependent temperature profile which without direct injection of the fuel into the exhaust system ( 20 ) was detected is detected. Application according to one of claims 4 to 6, characterized in that the fuel combustion in front of the exhaust gas turbocharger ( 30 ) and / or in front of the catalyst ( 40 ) from the real temperature rise above the catalyst ( 40 considering an additional tolerance and a comparison of this value with a temperature increase over the catalyst calculated in a model ( 40 ) is detected. Application according to one of claims 4 to 7, characterized in that at a detected fuel combustion in front of the exhaust gas turbocharger ( 30 ) and / or in front of the catalyst ( 40 ) the metered addition of the fuel with the fuel metering unit ( 60 ) is stopped or reduced. Application according to one of claims 4 to 7, characterized in that at a detected fuel combustion in front of the exhaust gas turbocharger ( 30 ) and / or in front of the catalyst ( 40 ) the metered addition of the fuel with the fuel metering unit ( 60 ) is increased. Use according to claim 9, characterized in that, when the metered addition is increased, the relative increase is dependent on the operating point in a chip unit ( 101 ) a control unit ( 100 ) is deposited. Application according to claim 9 or 10, characterized that at an increase dosing the relative increase is calculated by a turbocharger and / or exhaust pipe model. Application according to one of claims 4 to 11, characterized in that the for controlling the internal combustion engine ( 1 ) associated models according to the additional heat source in front of the exhaust gas turbocharger ( 30 ) and due to combustion in front of the catalyst ( 40 ) reduced flow of fuel into the catalyst ( 40 ) Getting corrected. Use according to claim 4 to 12, characterized in that the metered addition of fuel to achieve an optimal regeneration temperature with a post-injection at a Kraftstoffzumesssystem ( 11 ) on the engine block ( 10 ) is set. Device for controlling or regulating the Rußabbrandgeschwindigkeit in an internal combustion engine ( 1 ) with an engine block ( 10 ), an exhaust system ( 20 ) with a catalyst ( 40 ) and a downstream particle filter ( 50 ), whereby in front of the catalyst ( 40 ) a fuel metering unit ( 60 ) for the direct injection of the fuel into the Abgasfüh tion ( 20 ) is provided, characterized in that with a temperature sensor ( 80 ) the temperature in the exhaust system ( 20 ) in front of the catalyst ( 40 ) and with a temperature sensor ( 90 ) the temperature in the exhaust system ( 20 ) after the catalyst ( 40 ) can be determined and from the respective increase in temperature fuel combustion in front of the catalyst ( 40 ) is detectable. Apparatus according to claim 14, characterized in that the temperature sensors ( 80 . 90 ) by means of signal lines ( 81 . 91 ) with a control unit ( 100 ) for controlling the metering of fuel assemblies and the control unit ( 100 ) by means of a signal line ( 64 ) with the fuel metering unit ( 60 ) connected is. Device according to one of claims 14 to 15, characterized in that the control unit ( 100 ) by means of a signal line ( 12 ) with a fuel metering system ( 11 ) on the engine block ( 10 ) connected is. Device according to one of claims 14 to 16, characterized in that the control unit ( 100 ) at least one characteristic unit ( 101 ) having. Device according to one of claims 14 to 17, characterized in that in the exhaust system ( 20 ) in front of the temperature sensor ( 80 ) and the catalyst ( 40 ) an exhaust gas turbocharger ( 30 ) is arranged. Device according to one of claims 14 to 18, characterized in that the control unit ( 100 ) by means of a signal line ( 71 ) with another temperature sensor ( 70 ) in the exhaust system ( 20 ) in front of the exhaust gas turbocharger ( 30 ) connected is. Device according to one of claims 14 to 19, characterized in that the function of the control unit ( 100 ) is executed as software and / or hardware and is at least partially part of a higher-level engine control.