FR2888616A1 - Fuel introduction controlling or regulating method for e.g. diesel engine, involves using temperature sensor, placed in upstream of catalyst, to monitor if fuel is ignited already in exhaust gas pipe in upstream of catalyst/particle filter - Google Patents

Abstract

The method involves using a temperature sensor (80) to monitor if the fuel is ignited already in an exhaust gas pipe (20), of an internal combustion engine (1) e.g. e.g. diesel engine, in the upstream of a catalyst (40) or a particle filter (50). The sensor is installed in the upstream of the catalyst in the direction of the pipe. The fuel is monitored by comparing the increase in temperature measured at the catalyst with an increase in temperature calculated based on an exhaust gas temperature model. An independent claim is also included for a device for controlling or regulating the speed of combustion of carbon black in an internal combustion engine.

Description

Field of the invention

  The present invention relates to a method of controlling or regulating the introduction of fuel into an exhaust gas line of an internal combustion engine upstream of a catalyst or particulate filter.

  The invention also relates to a device for controlling or regulating the combustion rate of the black smoke or particles of an internal combustion engine comprising an engine block, an exhaust pipe equipped with a catalyst and a downstream particulate filter, a fuel metering unit directly injecting fuel into the exhaust gas line upstream of the catalyst.

  STATE OF THE ART Frequently, internal combustion engines, in particular diesel engines, are equipped with exhaust gas treatment systems comprising in particular a particulate filter or black-smoke filter or diesel particulate filter (DPF filter). To regenerate this particulate filter, temperatures above the usual exhaust gas temperatures are required. Without auxiliary measures, the particles oxidize at about 550-600 C. By combining the particulate filter and an oxidation catalyst (OXI-KAT) by catalytic coating of the filter and / or by addition of an additive the lower temperature threshold for oxidation can be reduced to about 250350 C.

  For some operating states of the internal combustion engine, regeneration has sometimes occurred in a controlled, too fast or too slow manner. In particular, in the case of uncontrolled, rapid combustion, the strong exothermic oxidation of the particles can produce an annoying release of heat which passes through the filter at a temperature front and generates very high temperatures. Such situations must be avoided in safety or, if they occur, they must be able to be controlled by appropriate measures. If the regeneration proceeds too slowly, regeneration measures must be taken too long, which increases fuel consumption. In addition, there is a risk of stopping the internal combustion engine or the transition to an operating state which produces the cessation of the regeneration.

  To avoid such situations, German Offenlegungsschrift 10333441 A1 discloses a method and a device for controlling the exhaust after-treatment system, in particular a particulate filter of an internal combustion engine. According to this document, a set value (LAS) for the lambda signal (L) or a variation of the lambda signal (L) is pre-defined. The actual value of the lambda signal (L) or the variation of the lambda signal (L) is detected. On the basis of the comparison between the actual value and the target value (LAS), a control signal for an actuating element is provided which makes it possible to control the reaction in the exhaust aftertreatment system so that bring the actual value closer to the set value (LAS). With the aid of actuating elements, it is possible to influence the amount of oxygen held in the exhaust gas. The actuating element is provided with the exhaust gas recirculation valve, the throttle flap, the actuating elements influencing the exhaust gas turbocharger and / or a fuel metering system which ensures a positive position. injection of fuel into the internal combustion engine.

  Document EP 1364110 B1 describes another method and a corresponding device according to which, in order to control the regeneration operation, a characteristic quantity is determined as a function of at least one operating parameter of the internal combustion engine and of at least one parameter of operation of the particulate filter; this characteristic quantity corresponds to the future intensity of the reaction of a particle filter. If the characteristic quantity exceeds a threshold value, at least one measure is taken to reduce the oxygen concentration in the exhaust gas of the internal combustion engine in order that the characteristic quantity does not reach the threshold value.

  If the particulate filter reaches a certain level of charge and the regeneration of the filter is not ensured due to the operating state of the engine, the state of the art plans to increase the temperature of the exhaust gas for the particles to burn quickly. For this, the concentration of hydrocarbons in the exhaust gas is increased; these hydrocarbons are then converted by the oxidation catalyst which results in an increase in temperature. The increase in the concentration of the exhaust gas is usually achieved by post-injection into the engine block fuel system by direct dosing of gas in the exhaust gas line. exhaust; the metered quantity is normally preset according to the operating point.

  If the diesel fuel is injected directly into the exhaust duct, all known processes assume that this fuel will be converted into the catalyst. But measurements show that ignition of the amount of fuel injected can already occur upstream of the catalyst. This is particularly the case if the injection is at least partly in the exhaust manifold. But a combustion upstream of the catalyst defaults the models and controls that result, which can result in considerable differences from the ideal situation.

  OBJECT OF THE INVENTION The object of the present invention is to reduce the combustion upstream of the catalyst by developing a method for controlling or regulating the combustion rate of black smoke or particles, making it possible on the one hand to diagnose this type of combustion. combustion and on the other hand if this happens, to react appropriately.

  The invention also aims to develop a device for controlling or regulating the particle combustion rate.

  DESCRIPTION AND ADVANTAGES OF THE INVENTION For this purpose, the invention relates to a method of the type defined above, characterized in that a measurement system is used to monitor whether the fuel has already ignited in the exhaust gas duct upstream of the catalyst or the particulate filter.

  The method according to the invention has the advantage of detecting a safety ignition fuel upstream of the catalyst. When the fuel ignites upstream of the catalyst, appropriate measures can be taken which, depending on the operating state of the internal combustion engine, allow optimum control or regulation of the combustion rate of the particles.

  If the monitoring is carried out using at least one temperature sensor installed upstream of the catalyst in the direction of passage of the exhaust gas, it is possible to detect an increase in temperature upstream of the catalyst if the hydrocarbons burn upstream catalyst. In this case, the quantity dosed will be increased by comparison with pure combustion in the catalyst to compensate for the heat losses generated.

  According to a preferred embodiment, the temperature increase measured at the catalyst is compared with a temperature increase calculated from a model. This makes it possible to take into account complex relationships that depend on a large number of influence coefficients.

  A preferred application of the process of the invention is characterized in that a temperature sensor is used to measure the temperature in the exhaust gas line upstream of the catalyst and with a temperature sensor the temperature in the exhaust gas line downstream of the catalyst, and from the respective increase in temperature is detected a fuel combustion upstream of the catalyst. From the temperature curves it is possible to detect the combustion front and according to the evolution appropriate measures are taken. This improves the control or regulation of the particle combustion rate during regeneration of the particulate filter.

  For current diesel engines, according to a preferred embodiment there is an exhaust gas turbocharger installed in the exhaust gas line upstream of the temperature sensor and the catalyst, and the combustion of the fuel in the engine is detected. exhaust gas ducting upstream of the exhaust gas turbocharger and / or the catalyst.

  According to a preferred characteristic, the fuel combustion is detected upstream of the exhaust gas turbocharger and / or upstream of the catalyst from the evolution of the temperature measured by the temperature sensor and its comparison with a prerecorded evolution or temperature curve which depends on the operating point, this evolution having been determined without direct injection of fuel into the exhaust gas pipe. This allows control or regulation of the particle combustion rate during regeneration of the particulate filter according to the state of operation.

  According to another preferred embodiment, fuel combustion is detected upstream of the exhaust gas turbocharger and / or upstream of the catalyst from the actual increase in the temperature at the catalyst, taking into account a additional tolerance and this value is compared with a temperature increase calculated in a model for the catalyst. The short temperature variations and tolerance deviations in the temperature sensors are taken into account in this operation.

  If the temperature upstream of the exhaust gas turbocharger is too high, by detecting the combustion of fuel upstream of the exhaust gas turbocharger and / or upstream of the catalyst, the fuel dosage can be stopped or reduced by fuel metering unit. This prevents overheating of the exhaust gas turbocharger and protects it against incidents.

  If, on the other hand, the temperature is too low and the re-generation of the particulate filter is not optimal, when a combustion of fuel is detected upstream of the exhaust gas turbocharger and / or upstream of the catalyst, the fuel dosage can be increased per fuel metering unit. This makes it possible to compensate for high heat losses.

  A particularly accurate assay is carried out, in particular by increasing the dosage, if the relative increase is recorded according to the operating point in a unit with characteristics fields of a control unit. This makes it possible, for example, to take into account the various operating states of the internal combustion engine and to control an optimum regeneration temperature of the particulate filter.

  Alternatively, in the case of an increase in dosage, the relative increase is calculated with a model of turbocharger and / or exhaust gas line. It also allows the use of flow models to optimize the particle combustion rate improving control or regulation.

  For a more precise overall control of the internal combustion engine, the models used for the control of the internal combustion engine can be corrected according to the additional heat source upstream of the exhaust gas turbocharger or because of the flow rate. reduced fuel in the catalyst due to combustion upstream of the catalyst. This improves the simulation models in the motor control and can for example improve the prognosis based on these models for different temperature sensors or pressure drop models.

  For assistance, the fuel dosage to achieve optimum regeneration temperature can be done by post-injection with the engine block fuel metering system.

  The problem posed for the device is solved in that with a temperature sensor the temperature is measured in the exhaust gas line upstream of the catalyst and with a temperature sensor the temperature in the gas line is measured. exhaust downstream of the catalyst and from the respective increase in temperature is detected a fuel combustion upstream of the catalyst. This makes it possible to recognize an increase in temperature upstream of the catalyst and also upstream of the particulate filter and thus to detect fuel combustion upstream of the catalyst.

  Depending on the operating state of the internal combustion engine, appropriate control actions are provided if the temperature sensors are connected by signal lines to the control unit to control the dosing of the fuel and if The control unit is connected by a signal transmission line to the fuel metering unit.

  If the control unit is connected by a signal transmission line to the engine block fuel metering system, in addition or alternatively the fuel metering by the fuel metering unit, a post-injection can be made with the engine block fuel metering system.

  If the control unit has at least one characteristic field unit, the metering of the fuel in the exhaust line can be done according to the operating point taking into account other engine parameters as well.

  In the case of an internal combustion engine equipped with a turbocharger, the exhaust gas turbocharger is installed in the exhaust pipe upstream of the temperature sensor and the catalyst, which makes it possible to increase significantly the power that gives the internal combustion engine.

  To protect the exhaust gas turbocharger against overheating, it is intended to connect the control unit by a signal transmission line to another temperature sensor installed in the exhaust pipe upstream of the turbocharger. exhaust gas. This is important for fuel combustion in the exhaust manifold of the engine block because in this case one can have extremely high temperatures at the turbo-compressor exhaust.

  According to a preferred embodiment, the function of the control unit can be realized in the form of a program and / or a circuit and be at least partially part of a superordinate motor control, a function recorded under A program form for controlling or regulating the particle combustion rate in a very simple manner, this function being integrated as a routine into the overall engine control or management program. This also allows for economic updates of the programs.

  The present invention will be described below in more detail with the aid of an exemplary embodiment shown schematically in the single appended figure.

  The single figure is a schematic view of a device for controlling or regulating the rate of combustion of particles in an internal combustion engine.

Description of the embodiment

  Figure 1 shows schematically the main components of an internal combustion engine 1 comprising a motor block 10, an exhaust gas pipe 20 equipped with a catalyst 40 and a particle filter 50 downstream. In the embodiment shown, the internal combustion engine 1 further comprises an exhaust gas turbocharger 30 installed in the exhaust gas line 20 upstream of the catalyst 40. A fuel metering unit 60 injects directly fuel in the exhaust gas line 20 upstream of the catalyst 40. The metering unit or fuel metering system 60 comprises a pump 63 and / or a valve 62 for accurately metering the fuel.

  This device corresponds in particular schematically to the construction of a diesel-type internal combustion engine 10 with a fuel metering system 60 which introduces the fuel into the exhaust gas pipe.

  According to the invention, in this device, the control or the re-regulation of the combustion rate of the particles or fumes black uses a temperature sensor 80 which determines the temperature in the exhaust gas line 20 upstream. catalyst 40 and a temperature sensor 90 which determines the temperature in the exhaust gas line 20 downstream of the catalyst 40; from the respective temperature increase it determines whether the fuel burns upstream of the catalyst 40. The temperature sensors 80, 90 are connected to a control unit 100 by signal transmission lines 81, 91. This unit controls the fuel dosage.

  The control unit 100 is connected by a signal transmission line 64 to the fuel metering unit 60. In addition, in the case of the device shown, the control unit 100 is connected by a transmission line of signal 12 to a fuel metering system 11 of the engine block 10. In addition, in the example shown, the control unit 100 is connected by a signal transmission line 12 to a fuel metering system. 11 of the engine block 10. In addition, in the example presented, the control unit 100 is connected by a signal transmission line 71 to another temperature sensor 70 installed in the exhaust gas duct 20. upstream of the exhaust gas turbocharger 30.

  According to a development of the invention, the function of the control unit for controlling or regulating the combustion rate of the particles is in the form of a program and / or a circuit and belongs at least partly to a superordinate engine control. The control unit 100 has at least one feature field unit 101 in which the metering of the fuel in the exhaust gas line 20 is recorded according to the operating point.

  The device as described above makes it possible to measure, with the temperature sensor 80, the temperature in the exhaust gas pipe 20 upstream of the catalyst 40 and with the temperature sensor 90, the temperature in the pipe of exhaust gas downstream of catalyst 40; from the respective rise in temperature, fuel combustion is detected upstream of the exhaust gas turbocharger 30 and / or catalyst 40. Fuel combustion upstream of the exhaust gas turbocharger 30 and / or upstream of the catalyst 40 is detected on the one hand starting from the evolution of the temperature measured by the temperature sensor 80 and its comparison with a temperature evolution recorded and depending on the operating point, and that the without fuel injection into the exhaust gas conduit 20. If the temperature upstream of the catalyst exceeds the previously recorded temperature curve, fuel combustion is effected upstream of the gas turbocharger. Exhaust 30 and / or upstream of the catalyst 40. In addition, this improves the detection by an exhaust gas temperature model.

  Another method is to detect the fuel combustion upstream of the exhaust gas turbocharger 30 and / or upstream of the catalyst 40 from the actual increase in temperature at the catalyst 40 taking into account the a complementary tolerance and comparing this value with a temperature increase at the catalyst 40, calculated using a model.

  As a reaction to a fuel combustion detection upstream of the exhaust gas turbocharger 30 and / or upstream of the catalyst 40 it is possible to stop or reduce the fuel dosage by the fuel metering unit 60 if for example the temperature upstream of the exhaust gas turbocharger 30 is too high. This makes it possible to monitor any overheating of the exhaust turbocharger 30 with the aid of the additional temperature sensor 70.

  Depending on the realization of the exhaust gas pipe 20 and the installation of the catalyst 40 and the particulate filter 50, other temperature sensors can also be provided in other places.

  If the temperature is too low to regenerate the particulate filter, it is possible, on the other hand, by detecting the combustion of fuel upstream of the exhaust gas turbocharger 30 and / or upstream of the catalyst 40, to increase the dosage of by the fuel metering unit 60 and for an increase in dosage the relative increase is recorded according to the operating point of a characteristic field 101 of the control unit 100. The relative increase can also be calculated from a model of turbocharger and / or exhaust gas pipe. From the point of view of the overall control of the internal combustion engine it is intended to correct the models used for the control of the internal combustion engine according to the additional heat source upstream of the exhaust gas turbocharger 30 and reduced fuel flow in the combustion catalyst 40 upstream of the catalyst 40. An additional fuel metering can be provided to achieve an optimum post-injection regeneration temperature at the fuel metering system 11 of the fuel cell. motor 10.

  The method as described and the device as presented make it possible to monitor an uncontrolled combustion of fuel upstream of the catalyst 40, which guarantees a more exact temperature change upstream of the particulate filter 50 and makes it possible to optimize the rate of combustion. Particles to regenerate the particulate filter 50. At the same time, there is protection against overheating of the exhaust gas turbocharger 30. In addition, the simulation models can be improved in the engine control.

  In principle, it is conceivable to use the device as described as well as the process also for other concepts of internal combustion engines 1, for thermal machines or heating applications in which it is necessary to have a precise combination of the particles for regenerate particulate filters 50.

NOMENCLATURE

  1 internal combustion engine engine block 11 fuel metering system 12 signal transmission line 20 exhaust gas line exhaust gas turbocharger catalyst particulate filter fuel metering unit 61 nozzle 62 valve 63 pump 64 line signal transmission temperature sensor 71 signal line temperature sensor 81 signal line 90 temperature sensor 91 signal line control unit 101 field unit

Claims (20)

  1) A method of controlling or regulating the introduction of fuel into an exhaust gas line (20) of an internal combustion engine (10) upstream of a catalyst (40) or a particulate filter (50), characterized in that by means of a measuring device it is monitored whether the fuel has already ignited in the exhaust gas line (20) upstream of the catalyst (40) or particulate filter (50).   2) Method according to claim 1, characterized in that the monitoring is carried out using at least one temperature sensor (80) installed upstream of the catalyst (40) in the direction of flow of the exhaust gas. .   3) Process according to claim 1, characterized in that the temperature increase measured at the level of the catalyst (40) is compared with a temperature increase calculated according to a model.   4) Application of the method according to one of claims 1 to 3 for controlling or regulating the combustion rate of the black smoke in an internal combustion engine (1) comprising an engine block (10), a pipe of exhaust gas (20) equipped with a catalyst (40) and a particulate filter (50) downstream, and upstream of the catalyst (40) a fuel metering unit (60) for direct injection of fuel in the exhaust gas line (20), characterized in that the temperature in the exhaust gas line (20) upstream of the catalyst is measured by means of a temperature sensor (80). (40) and with a temperature sensor (90) the temperature in the exhaust gas line (20) downstream of the catalyst (50) is measured, and from the respective temperature increase a combustion of fuel upstream of the catalyst (40).   5) Application according to claim 4, characterized by an exhaust gas turbocharger (30) installed in the exhaust pipe (20) upstream of the temperature sensor (80) and the catalyst (40), and the fuel combustion in the exhaust gas line (20) is detected upstream of the exhaust gas turbocharger (30) and / or the catalyst (40).   6) Application according to claim 5, characterized in that the fuel combustion is detected upstream of the exhaust gas turbocharger (30) and / or upstream of the catalyst (40) from the evolution of the temperature. measured by the temperature sensor (80) and the comparison with a previously recorded temperature change which depends on the operating point, which evolution has been determined without direct fuel injection in the exhaust pipe (20).   7) Application according to claim 5, characterized in that the combustion of fuel is detected upstream of the exhaust gas turbocharger (30) and / or upstream of the catalyst (40) from the actual increase of the temperature in the catalyst (40) taking into account an additional tolerance and a comparison of this value with a temperature increase calculated from a model for the catalyst (40).   8) Application according to claim 5, characterized in that fuel metering is stopped or reduced by the fuel metering unit (60) if a fuel combustion is detected upstream of the gas turbocharger. exhaust (30) and / or upstream of the catalyst (40).   9) Application according to claim 5, characterized in that the dosage of the fuel is increased by the metering unit (60) if a fuel combustion is detected upstream of the exhaust gas turbocharger (30) and or upstream of the catalyst (40).   10) Application according to claim 9, characterized in that, in the case of an increase in dosage, the relative increase according to the operating point is recorded in a characteristic field unit (101) of a control unit (100). .   11) Application according to claim 9, characterized in that one calculates the relative increase by a model of turbocharger 10 and / or exhaust gas line in case of increase of dosage.   12) Application according to claim 5, characterized in that the models used to control the internal combustion engine (1) are corrected according to the additional heat source upstream of the exhaust gas turbocharger (30) and the reduced fuel stream in the catalyst (40) due to combustion upstream of the catalyst (40).   13) Application according to claim 4, characterized in that the dosing of the fuel is adjusted to achieve an optimum regeneration temperature by a post-injection into the fuel metering system (11) of the engine block (10).   14) Device for controlling or regulating the combustion rate of the flue gas in an internal combustion engine (1) comprising an engine block (10), an exhaust pipe (20) equipped with a catalyst (30) and a downstream particulate filter (50), a fuel metering unit (60) directly injecting fuel into the exhaust gas line (20) upstream of the catalyst (40), characterized by a temperature sensor (80) which measures the temperature in the exhaust gas duct (20) upstream of the catalyst (40) and a temperature sensor (90) which measures the temperature in the gas duct exhaust (20) downstream of the catalyst (40) and from the respective increase in temperature is detected the fuel consumption upstream of the catalyst (40).   Device according to Claim 14, characterized in that the temperature sensors (80, 90) are connected by signal transmission lines (81, 91) to a control unit (100) for controlling the fuel dosage, and said control unit (100) is connected by a signal transmission line (64) to the fuel metering unit (60).   16) Device according to claim 15, 1 o characterized in that the control unit (100) is connected by a signal transmission line (12) to a fuel metering system (11) of the engine block (10). ).   17) Device according to claim 15, characterized in that the control unit (100) comprises at least one characteristic field unit s (101).   18) Device according to claim 15, characterized by an exhaust gas turbocharger (30) installed in the exhaust pipe (20) upstream of the temperature sensor (80) and the catalyst (40).   19) Device according to claim 18, characterized in that the control unit (100) is connected by a signal transmission line (71) to another temperature sensor (70) in the exhaust gas pipe ( 20) upstream of the exhaust gas turbocharger (30).   Device according to claim 15, characterized in that the function of the control unit (100) is in the form of a program and / or circuit and is at least part of a superordinate motor control.   the function of the control unit (100) is implemented as a program and / or circuit and is at least part of a subordinate motor control.