Method for operating a system for supplying an air mass flow to a burner

Abstract

Method for operating a system (40) for supplying an actual air mass flow (ms55,actual) to a burner (43) - in particular a burner (43) in which an exhaust gas is generated and this is fed to a catalytic converter (37) of an internal combustion engine (13) for its conditioning - with a valve (61) in the feed to the burner (43), which valve can be adjusted to a maximum open position and a minimum open position, characterized in that a power (P58) of the pump (58) is determined from a property which correlates with a switching position (ST61) of a valve closure (V61).

Description

Prior ArtIt is known that the use of three-way catalysts is necessary to achieve emission limit values. Such emission limit values are determined, for example, by the EU exhaust gas standard EU6. These three-way catalysts make possible a conversion of the relevant gaseous pollutants, such as nitrogen oxide NOx, hydrocarbons HC and carbon monoxide CO, into harmless products, such as nitrogen N2, water H2O and carbon dioxide CO2. In order for the catalytic reactions required for this to proceed, the temperature in the catalyst, the so-called light-off temperature, must typically exceed 300° C. to 400° C. Once this temperature is reached, the catalyst converts the relevant pollutants almost completely. In order to achieve this state as quickly as possible, so-called internal-engine catalyst heating measures are already used. By means of these internal-engine catalytic converter heating measures, the efficiency of the internal combustion engine (in particular a spark ignition engine) is changed by late ignition angles, for example, in such a way that the exhaust gas temperature and the so-called enthalpy input into the catalytic converter are increased. Intelligent injection strategies (e.g. multiple injections) simultaneously ensure stable combustion. With the test cycles valid up to now (NEDC, FDP 75), which all begin with an extended idling phase, a fast light-off temperature with low emissions could thus be ensured.In addition to these internal engine catalyst heating measures, external catalyst heating measures have also been studied in the past. These include, for example, electrically heatable catalytic converters, but also so-called exhaust gas burners, as are known, for example, from the published patent applications DE 41 32 814 A1 and DE 195 04 208 A1.In connection with previously applicable exhaust gas standards, it was nevertheless possible, despite the ever more stringent requirements in the past, to adhere to these requirements solely by internal combustion catalyst heating measures. For this reason, the aforementioned external catalytic converter heating measures, such as the electrically heatable catalytic converter or the exhaust gas burner, or burners for short, have not yet been able to pass through the market. With the introduction of the determination of emissions determined during real road driving (real driving emissions, RDE), driving situations in which the conversion of various exhaust gas constituents by the above-mentioned three-way catalytic converters alone by internal engine catalytic converter heating measures is rather not possible gain higher significance. These so-called RDE boundary conditions also include, for example, the so-called urban spontaneous cold departure of a motor vehicle, which can proceed with a high engine load in combination with a very short idling phase that previously occurred. Such real driving conditions bring the known internal engine catalyst heating to its limits, in particular if at the same time further reduced emission limit values are to be expected, which must be complied with. This is expected, for example, for the EU exhaust gas standard EU7. In connection with these requirements, a so-called exhaust gas burner turns out to be an extremely effective measure. By means of such an exhaust gas burner it is possible to bring a three-way catalytic converter extremely quickly to the light-off temperature mentioned, at which the pollutants are converted very early.Embodiments of the InventionAccording to a first embodiment of the invention, a method for operating a plant for supplying air by means of an actual air mass flow to a burner-in particular a burner in which an exhaust gas is generated and this exhaust gas is supplied to a catalytic converter of an internal combustion engine for conditioning the exhaust gas-is provided. In the supply to the burner is a valve which can be adjusted, inter alia, into a maximum open position and a minimum open position. From a property correlated with a switching position of a valve closure, a power of the pump is determined. This has the advantage that a diagnosis of the performance of the pump can thereby be carried out, in particular at relatively high counter pressures. By means of this diagnosis and knowledge of the performance of the pump, the control or regulation of the actual air mass flow can be carried out in an improved manner. This procedure ultimately simulates a counterpressure of the exhaust gas of the internal combustion engine. A relatively high counterpressure of the exhaust gas brings about, at an outlet of the valve, in the valve and also upstream of the valve downstream of the pump, a resistance against which the pump must operate in order to be able to convey an-for example predetermined-actual air mass flow. Such a simulation of high counter pressures of the exhaust gas through the valve can be carried out by the adjustable open position at any desired point in time. For example, this can also be done at very low loads in pure exhaust gas or burner operation, i.e. when, for example, the internal combustion engine is not or is not yet operating.According to a further aspect of the invention, it is provided that the switching position of the valve closure is adjusted during operation of the burner and simultaneous operation of the internal combustion engine. By means of such a procedure, it is possible to determine the output of the pump even in parallel operation of the exhaust gas burner and of the internal combustion engine. In particular, a small open position with high flow resistance allows superimposed dynamic effects to be shielded, which are caused by the operation of an internal combustion engine with a plurality of cylinders, especially by the gas exchange. These dynamic effects can cause brief large deviations (adaptation) in the evaluation of the performance of the pump. These dynamic effects make possible evaluation of the pump output (delivery output) difficult, especially in regions of high loads.According to a further aspect of the invention, it is provided that the valve closure can be adjusted and is adjusted in at least one intermediate position between the maximum open position and the minimum open position. This enables finer adjustment of an opening of the valve. In order to carry out the method, a defined open position of the valve is set. In particular, an open position is set which, when the pump is pumping or switched on, generates a high flow resistance, as a result a lower throughflow and thus a higher pressure or counterpressure between the pump and the valve. An increase in the pressure is dependent on the controlled air quantity and can be determined empirically by measurements for the respective system.According to a further aspect of the invention, it is provided that the switching position of the valve closure is evaluated by means of a switching position sensor system. Such a valve advantageously offers the possibility of setting a wide variety of opening states of the valve-in particular opening angle of a flap or thrust positions of a slide-during operation and determining a set opening angle or a thrust position at any time.The greater an opening angle of the valve closure within the valve, the greater the actual air mass flow through the valve and the lower a dynamic pressure upstream of the valve, i.e. between the pump and the valve. In a valve with various adjustable opening angles, the actual air mass flow can be specified as a function of the angular position or the opening angle. According to a further aspect of the invention, it is provided that a relationship between an actual air mass flow, a pressure-in particular a pressure-between the valve and the pump-and a switching position of the valve closure is determined and stored as a characteristic diagram. Advantageously, the output of the pump can be determined by means of the relationship between the actual air mass flow and the switching position of the valve closure.According to a further aspect of the invention, it is provided that a switching position of the valve closure is adjusted in order to adjust a specific actual air mass flow at a specific pressure between the valve and the pump. If, according to a further aspect of the invention, a deviation between a setpoint air mass flow and an actual air mass flow is then determined, an adaptation value can then be determined in order to correct a quantitative setting of the actual air mass flow. This allows the apparatus, here the pump, to be adapted to technical changes of the pump during operation (for example. This is because wear, running-in of bearings) and subsequent changes in behavior can be compensated for.According to a further aspect of the invention, it is accordingly provided that a power of the pump is set by means of the adaptation value in order to convey a setpoint air mass flow and then to determine a quality of the adaptation value from the relationship between the actual air mass flow, the pressure between the valve and the pump and the switching position of the valve closure.If a deviation of the setpoint air mass flow from the actual air mass flow is detected, the adaptation value is changed. By this monitoring of the adaptation value, it can be ensured that the qualitative properties of the device, here the pump and the exhaust gas behavior of the burner, are maintained.A computer program is also provided which is designed to execute all the steps of one of the methods or to be programmed in such a way that it executes a method when it is executed on a computer. In addition, a machine-readable storage medium is provided on which the computer program is stored or on which the computer program is stored for application in a method. Furthermore, a control device is provided which is designed to carry out all steps of one of the methods or to be programmed for use in a method.The invention is explained in more detail below with reference to the two figures shown. The following are shown: FIG. 1 is a schematic view of the system for supplying air to a burner, FIG. 2 shows a schematic illustration of a valve, for example designed as a throttle valve, FIG. 3 schematically shows a relationship between a position of a valve closure on the basis of the opening angle and a pressure and an actual air mass flow.FIG. 1 shows a device 10, which is in particular a motor vehicle. This device 10 has an internal combustion engine 13 which is supplied with air via an intake device 16. This intake device 16 has an air inlet 19. In the supply of air to the internal combustion engine 13, there is furthermore a sensor arrangement 22, which can have a sensor element-for example a hot film air mass meter-or at least one further sensor element, and subsequently a valve 25, which is typically designed as a so-called throttle valve. The valve 25 is followed by a sensor arrangement 26 which has, for example, a pressure sensor. The air inlet 19 typically leads into a so-called box 28 (air filter box), so that the introduced air initially flows through the air inlet 19 and then flows through an air filter, not designated in any more detail here. The intake device 16 has an intake pipe 31 in which the sensor arrangement 22 is arranged. The valve 25 is also arranged in this intake pipe 31. The exhaust gases or combustion gases generated by the internal combustion engine 13 are introduced into an exhaust system 34. The exhaust gases first flow past a sensor arrangement 27-embodied as a lambda probe-in order to then be introduced into the following parts of the exhaust system 34. Parts of this exhaust system 34 are here, for example, a first catalytic converter 37, a second catalytic converter 38 and a petrol particle filter 39, through which exhaust gas flows in this sequence. After the first catalytic converter 37, the exhaust gases flow past a sensor arrangement 41-constructed as a lambda probe. After passing through the gasoline particle filter 39, the converted exhaust gases are discharged into the environment (arrow) or, depending on the exhaust system system, flows through this further exhaust gas aftertreatment system.In FIG. 1, the plant 40 for supplying air to a burner 43 is furthermore illustrated. This plant 40 also has an air inlet 46 which constitutes an inlet to a box 49. An air filter can also be arranged in this box 49. The boxes 28, 49 can also be designed as a box, as is symbolically represented by the dashed rectangle around both boxes 28, 49, without further designation. Accordingly, such a combined box can also have only one air inlet, which combines the two air inlets 19, 46. In addition, such a box can also have a single air filter, which is representative of the two air filters mentioned above. The air passing through the air inlet 46 into the box 49 then enters an intake pipe 52, in which a sensor arrangement 55, which can have a sensor element-for example a hot film air mass meter-or at least one further sensor element-is likewise arranged. The sensor arrangement 55 can be designed, for example, as a sensor element for detecting pressure. If this sensor arrangement 55 is part of a so-called hot film measuring probe, for example, this can serve, in addition to the air mass flow, as a whole, to determine the pressure, temperature and humidity of the air. The incoming air then passes a pump 58 and is supplied by this pump 58 to a valve 61 (shut-off valve). As the name already states, this valve 61 serves to shut off the air supply to the burner 43. the device 10 shown here also has a control unit 70, which is designed as a so-called engine control unit (engine control unit). The control device 70 is connected to individual components of this device 10 via signal lines, which are not designated in more detail here. These signal lines are used for communication between the individual components and the control device 70.The burner 43 is in operation and is supplied with fuel via a fuel supply unit 44-for example, designed as an injector. By supplying or delivering air by means of the pump 58-the open valve 61 is illustrated here by the schematically illustrated open flap-by the system 40 for supplying air, a fuel-air mixture can then be formed in the burner 43, which mixture is ignited and burned by an ignition unit 45-for example embodied as a spark plug. The exhaust gas discharged from the burner 43 flows past a sensor arrangement 47, designed as a lambda probe, and is introduced into the exhaust system 34 via an individually designed introduction path and heats the catalytic converter 37 in a particularly quick manner. The device 10 shown here also has a control unit 75, which is designed as a so-called burner control unit (engine control unit). The control device 75 is connected to individual components of this device 10 via signal lines, which are not designated in more detail here. The two control units 70, 75 exchange signals via signal lines, not shown, and are thus able to communicate with one another.It is provided that the valve 61 and its valve closure V 61 can be operated not only in two switching positions ST 61, i.e. on the one hand "fully closed" in the switching position ST 61 and on the other hand "fully opened" in the switching position ST 61, but further switching positions ST 61 of the valve closure V 61 can be adjusted with a wide variety of opening angles a between the switching position ST 61 "fully closed" and the switching position ST 61 "fully open". For example, for any entire degree of angle a between 0° (fully open) and 90° (fully closed), it is possible to adjust the valve closure V 61. A device for determining the position of the valve closure should also be assigned to such a valve 61 (switching position sensor system). As a result, it is possible during operation of the device 10 and of the burner 43 to evaluate the corresponding position or switching position ST 61 for each position of the valve closure V 61 and to communicate it to the control unit 75. By means of this possibility, a determination of a power P 58 of the pump 58 (diagnosis of the pump power) is to be carried out, in particular at a so-called counterpressure P 58, preferably at a high counterpressure P 58.The pump 58 supplies filtered fresh air to the burner 43. In order to regulate the pump 58 and thus the supplied air mass, the sensor 55 (for example. Air Mass Meter (HFM)) was used. In the control unit 75 of the burner 43, the actual air mass flow ms55,istmeasured or determined by the sensor 55 is compared with a setpoint air mass flow ms55,soll, and a pilot control of the pump 58 is changed or corrected accordingly in order to set the desired setpoint air mass flow ms55,soll. From deviations between the setpoint air mass flow ms55,solland the measured actual air mass flow ms55,ist, an adaptation is calculated which is used for the diagnosis of components of the exhaust gas burner system. For example, it is provided that the adaptation is used for the diagnosis of the pump 58 and, if appropriate, indicate a malfunction of the pump 58.Accordingly, a method is provided for operating a plant 40 for supplying an actual air mass flow ms55,istto a burner 43 in which an exhaust gas is generated. For its conditioning (heating, operating temperature), the exhaust gas is fed to a catalytic converter 37 of an internal combustion engine 13-with a valve 61 in the feed to the burner 43, which can be or is adjustable into a maximum open position and a minimum open position (valve is closed). From a property (switching position, opening position, in particular opening angle of a valve closure) which correlates with a switching position ST 61 of a valve closure V 61, a power P 58 of the pump 58 is determined.The greater an opening angle a of the valve closure V 61 within the valve 61, the greater a mass flow (actual air mass flow m 55, ist) through the valve 61 and the smaller a dynamic pressure p 61 generated by the pump 58 in front of the valve 61. In the case of a valve 61 having different opening angles a, the mass flow (actual air mass flow m 55, ist) can be specified as a function as a function of a position of the valve closure V 61 (opening angle a), compare with FIG. 2 The switching position ST 61 of the valve closure V 61 is adjusted into an intermediate position between the maximum open position and the minimum open position. It is provided that the switching position ST 61 of the valve closure V 61 is adjusted during operation of the burner 43 and simultaneous operation of the internal combustion engine 13. Alternatively, the switching position ST 61 of the valve closure V 61 can be adjusted during operation of the burner 43 and of an internal combustion engine 13 which is not operated at the same time.FIG. 3 schematically shows a relationship between the position ST 61 of the valve closure V 61 on the basis of the opening angle a between 0° and 90° and a pressure and an actual air mass flow ms55,... flowing through. If the opening angle a=0°, i.e. the valve closure V 61 is closed, the actual air mass flow ms55,ist=0 and a pressure or dynamic pressure p 61 upstream of the valve 61 is at a maximum. If the opening angle a=90°, i.e. the valve closure V 61 is open, the actual air mass flow ms55is maximum corresponding to the current output P 58 of the pump 58 and the dynamic pressure p 61 upstream of the valve 61 is minimum. For the various positions of the valve closure V 61 with an opening angle a between the angles 0° and 90°, a corresponding actual air mass flow ms55,is established for a specific current output P 58 of the pump 58, at a ram pressure p 61 which is dependent on the current angle a. The relationship mentioned here between the actual air mass flow ms55,ist, the pressure - in particular determined - between the valve 61 and the pump 58 and a switching position ST61 of the valve closure V61 is determined and stored as a characteristic diagram. A defined opening angle a at the valve 61 is set in order to generate a lower actual air mass flow ms55,istand thus a higher counterpressure p61between the pump 58 and the valve 61. An increase in the pressure p61 is dependent on the controlled air quantity and can be determined empirically by measurements for the respective system. During operation of the burner 43, the output P58 of the pump 58 is determined by means of the relationship between the actual air mass flow ms55,istand the switching position ST61of the valve closure V61. For this purpose, a switching position ST61 of the valve closure V61 is set in order to set a specific actual air mass flow ms55,ist at a specific pressure between the valve 61 and the pump 58.On the basis of the characteristic curve of the counterpressure p61 over the opening angle a of the valve 61, a defined actual air mass flow ms55,ist and thus a defined exhaust gas counterpressure p61 can be set at which the output P58 of the pump 58 is to be checked.In a further step, a deviation dms55 between a setpoint air mass flow ms55,soll and an actual air mass flow ms55,ist is optionally determined and then an adaptation value is determined in order to correct a quantitative setting of the actual air mass flow ms55,ist, if appropriate.A power P 58 of the pump 58 is set by means of the adaptation value in order to convey a setpoint air mass flow ms 55,solland then to determine a quality of the adaptation value from the relationship between the actual air mass flow ms 55,ist, the pressure between the valve 61 and the pump 58 and the switching position ST 61 of the valve closure V 61.If a deviation of the setpoint air mass flow ms55,soll from the actual air mass flow ms55,soll results from this, the adaptation value is changed.By this evaluation of the adaptation value, the power P 58 of the pump 58 can thus be ensured and diagnosed even at higher exhaust gas backpressures. This "simulation" of high exhaust gas backpressures by the valve 61 can be performed by the adjustable opening angle a at any given time. For example, even in the case of actual very low loads in pure exhaust gas burner operation, i.e. when the internal combustion engine 10 is not in operation.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 41 32 814 A1

[0002] DE 195 04 208 A1

[0002]

Claims

Method for operating a plant (40) for supplying an actual air mass flow (ms55,ist) to a burner (43) - in particular a burner (43), in which an exhaust gas is generated and this is supplied to a catalytic converter (37) of an internal combustion engine (13) for conditioning the exhaust gas - having a valve (61) in the supply to the burner (43), which valve can be adjusted into a maximum open position and a minimum open position, characterized in that a power (P58) of the pump (58) is determined from a property which correlates with a switching position (ST61) of a valve closure (V61).Method according to Claim 1, characterized in that the switching position (ST61) of the valve closure (V61) is adjusted into an intermediate position between the maximum open position and the minimum open position.Method according to Claim 1 or 2, characterized in that the switching position (ST61) of the valve closure (V61) is set during operation of the burner (43) and simultaneous operation of the internal combustion engine (13).Method according to Claim 1 or 2, characterized in that the switching position (ST61) of the valve closure (V61) is set during operation of the burner (43) and of an internal combustion engine (13) which is not operated at the same time.Method according to Claim 1, 2 or 3, characterized in that the switching position (ST61) of the valve closure (V61) is evaluated by means of a switching position sensor system.Method according to one of the preceding claims, characterized in that a relationship between an actual air mass flow (ms55,ist), a - in particular determined - pressure between the valve (61) and the pump (58) and a switching position (ST61) of the valve closure (V61) is determined and stored as a characteristic diagram.Method according to Claim 6, characterized in that the power (P58) of the pump (58) is determined by means of the relationship between the actual air mass flow (ms55,ist) and the switching position (ST61) of the valve closure (V61).Method according to Claim 7, characterized in that a switching position (ST61) of the valve closure (V61) is set in order to set a specific actual air mass flow (ms55,ist) at a specific pressure between the valve (61) and the pump (58).Method according to Claim 6, 7 or 8, characterized in that a deviation (dms55) between a setpoint air mass flow (ms55,soll) and an actual air mass flow (ms55,ist) is determined and an adaptation value is then determined in order to correct quantitative setting of the actual air mass flow (ms55,ist).Method according to Claim 9, characterized in that a power (P58) of the pump (58) is set by means of the adaptation value in order to convey a setpoint air mass flow (ms55,soll) and a quality of the adaptation value is then determined from the relationship between the actual air mass flow (ms55,soll), the pressure between the valve (61) and the pump (58) and the switching position (ST61) of the valve closure (V61).Method according to Claim 10, characterized in that, in the event of a deviation of the setpoint air mass flow (ms55,soll) from the actual air mass flow (ms55,solt), the adaptation value is changed.A computer program adapted to perform all the steps of any of the methods according to any of claims 1 to 11 or to be programmed to perform a method according to any of claims 1 to 11 when executed on a computer.Machine-readable storage medium on which the computer program according to Claim 12 is stored or on which the computer program according to Claim 12 is stored for application in a method of Claims 1 to 11.A controller (75) configured to perform all the steps of any of the methods of any of claims 1 to 11 or programmed for use in a method of any of claims 1 to 11.

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