Title of Invention

A METHOD FOR CONTROLLING AN INTERNAL COMBUSTION ENGINE HAVING AN AIR SYSTEM

Abstract

The invention relates to a method and to a device for controlling an internal combustion engine that is provided with an air system. At least one value that characterizes the air system is determined by means of a model, on the basis of at least one correcting variable and/or at least one measured variable that characterizes the condition of the ambient air. The inventive model comprises at least one first and one second submodel. The starting values are determined by means of a submodel on the basis of input values. The correcting variable and/or the measured variable, in addition to at least one starting value of a second submodel, are taken into account for the input values of the first submodel.

Full Text

Method and device for controlling an internal combustion engine with an air system Prior art The invention relates to a method and a device for controlling an internal combustion engine with an air system. A method and a device for controlling an internal combustion engine with an air system is known, for example, from DE 197 56 619. Said publication describes a system for operating an internal combustion engine, in particular in a motor vehicle, in which the air is fed to a combustion chamber via a throttle valve arranged in an intake manifold, the mass flow rate via the throttle valve being determined. Here, a valve is arranged in an exhaust gas feedback line the mass flow rate via the valve in the exhaust gas feedback line also being determined. The air mass flow rate into the combustion chamber is determined on the basis of the two air mass flow rates. A problem with this device is that various values which are required for the calculation can only be registered with difficulty by means of sensors. It is disadvantageous therefore that a large number of sensors is necessary to register the various values. Advantages of the invention With the procedure according to the invention it is possible to determine at least one variable which characterizes the air system. Here, only a small number of measured variables, which can be registered by means of simple, cheap sensors, are necessary. Furthermore, variables which are present internally in the control unit during the control of the internal combustion engine are required. It is particularly advantageous that the model comprises at least a first and second partial model which determine output variables on the basis of input variables, not only at least one output variable of a second partial model but additionally the manipulated variable and/or measured variables being taken into account as input variables of the first partial model. The formation of the model is particularly simple if a fuel quantity ME which characterizes the fuel quantity to be injected, an exhaust gas feedback duty factor ATV which characterizes the actuation signal for an actuator for influencing the exhaust gas feedback and/or a supercharger duty factor LTV which characterizes the actuation signal for an actuator for influencing the characteristic of a turbine are used as manipulated variables. Preferably, not only the fuel quantity ME but additionally the exhaust gas feedback duty factor ATV and/or the supercharger duty factor are used. This is carried out as a function of whether the internal combustion engine is equipped with an exhaust gas feedback system and/or a supercharger. At least one rotational speed variable (N) which characterizes the rotational speed of the internal combustion engine, an ambient temperature (Tl) which characterizes the temperature of the ambient air and/or an ambient pressure (PI) which characterizes the pressure of the ambient air are used as a measured variable. The rotational speed, the ambient temperature and the ambient pressure are preferably used. Advantageous and expedient refinements and developments of the invention are characterized in the subclaims. Drawing The invention is explained in more detail below with reference to the embodiments illustrated in the drawing, in which Figure 1 shows a schematic view of the internal combustion engine together with the air system. Figure 2 shows the overall model of the air system as a block diagram, and Figures 3 to 8 show the various partial models as block diagrams. Description of the exemplary embodiments The procedure according to the invention is described below with reference to the example of a diesel internal combustion engine. The invention is however not restricted to application in diesel internal combustion engines, it can also be used in other internal combustion engines, in particular in direct-injecting petrol internal combustion engines. A specific quantity of fuel ML22 which contains specific oxygen content M022 is fed to an internal combustion engine 100 via a high-pressure fresh air line 102. The variable M022 is also referred to as oxygen content before the combustion. The high-pressure fresh air line 102 is composed of two parts. A first part is designated by 102 a, and a second part is designated by 102 b. The first part corresponds to the line up to the admixture of exhaust gas. The second part 102b corresponds to the line downstream of the admixture of exhaust gas. In the [sic] first part 102a can contain a supercharging air cooler 104. The air in the first part of the high-pressure fresh air line 102a has a temperature T2 and a pressure P2. Via a low-pressure fresh air line 108, the ambient air is fed to a compressor 106 and then flows via the supercharging air cooler 104 into the high-pressure fresh air line 102 Via the compressor, the air quantity ML21 flows with the oxygen content M021 into the high-pressure fresh air line 102. The air quantity ML21 with the oxygen content M021 which flows through the low-pressure fresh air line 108 corresponds to the air quantity with the corresponding oxygen content which flows through the compressor 106 and/or through the supercharging air cooler 104. The temperature Tl and the pressure PI which prevails in the low-pressure fresh-air line 108 corresponds to the ambient conditions, i.e. the ambient pressure and the ambient temperature. From the internal combustion engine 100, the air quantity ML31 with the oxygen content M031 flows into a high-pressure exhaust gas line 110. The variable M031 is also referred to as oxygen content after the combustion. The temperature T3 and the pressure P3 prevail in the high-pressure exhaust gas line 110. These values are also referred to as exhaust gas pressure P3 and exhaust gas temperature T3. An air quantity ML32 is fed from the high-pressure exhaust gas line 110 to a turbine 112, which is also referred to as air quantity via the turbine. From, the turbine 112, the exhaust gas is fed into a low-pressure exhaust gas line 114 which is also referred to as exhaust pipe 114 . The temperature T4 and the pressure P4 prevail in the low-pressure exhaust gas line. The turbine 112 drives the compressor 106 via a shaft 111. The rotational speed NL of the shaft is referred to as the rotational speed of the supercharger. The characteristic of the turbine and thus of the entire supercharger can be influenced by means of a supercharger actuator 113. In order to actuate it, the supercharger actuator 113, an actuation signal LTV which results in an adjustment of the supercharger by a travel LH is applied to it. The variable LH is also referred to as a supercharger travel, and the variable LTV as supercharger duty factor. Between the high-pressure exhaust gas line 110 and the high-pressure fresh air line 102 there is a connection which is referred to as exhaust gas feedback line 116. The air quantity MA which contains the oxygen content MOA flows through this exhaust gas feedback line 116. The cross section of the exhaust gas feedback line 116 can preferably be controlled by means of an exhaust gas feedback valve 118. In order to actuate the exhaust gas feedback actuator 119, an actuation signal ATV which results in an adjustment of the exhaust gas feedback valve 118 by a travel AH is applied to it. The variable AH is also referred to as exhaust gas feedback travel, and the variable LTV is referred to as exhaust gas feedback duty factor. The rotational speed N at the crank [sic] and/or the cam shaft of the internal combustion engine is preferably registered by means of a rotational speed sensor 101. Furthermore, quantity final control elements 103 which determine the fuel quantity ME which is to be injected and which is fed to the internal combustion engine are provided. For this purpose, a quantity signal ME is applied to the final control elements 103. In order to control the internal combustion engine and/or the final control elements 118 and 113 precisely, various values of those illustrated should be known. In particular, the oxygen quantity or the oxygen content M022 which is fed to the internal combustion engine should be known. The oxygen quantity determines, together with the injected fuel quantity ME, the exhaust gas emissions, in particular the soot emissions in the case of diesel internal combustion engines. Furthermore, it is advantageous if the various pressure values and temperature values are known. In addition it is advantageous if the rotational speed of the supercharger NL is known. These variables can be used to monitor the overall systemic and/or to control/regulate. It is particularly advantageous if these variables are not registered directly but rather are determined by means of a model and/or one or more partial models. In this case, no corresponding sensors are required. According to the invention there is provision that, by means of at least one model, one or more of the variables which characterize the air system are determined on the basis of one or more manipulated variables, in particular for the injected fuel quantity ME, the manipulated variable for the exhaust gas feedback valve ATV and the manipulated variable LTV for the turbine 112, and at least one measured variable relating to the ambient temperature Tl and/or the ambient pressure PI. It is particularly advantageous if the one or more variables which characterize the air system are determined on the basis of the fuel quantity ME, to be injected, of the rotational speed N, of a variable which characterizes the ambient temperature Tl and the ambient pressure PI, in addition the manipulated variable of the exhaust gas feedback valve 118 and the manipulated variable of the supercharger 112 being used. It is particularly advantageous here that the fuel quantity to be injected does not need to be registered as this variable is already previously known and is used for controlling the internal combustion engine. In particular, an internal variable present in the control unit is used for this. Likewise, the rotational speed N of the internal combustion engine is known as this is also indispensable for controlling the internal combustion engine. The same applies to the temperature, and the [sic] pressure Tl and PI. The same applies with the actuation signals for the final controlling elements 118 and 112. It is particularly advantageous that various partial models are formed for component systems, each partial model calculating different input variables and different output variables as a function thereof. There is provision here that different input variables of different models are formed by means of output variables of other models. Only easy to register measured variables or known manipulated variables are necessary as input variables of the overall model as a sum of the various partial models. The overall model of the air system and the division into the partial models of the air system are illustrated in Figure 2. In modern internal combustion engines, increasingly stringent demands are being made on the exhaust gas values and consumption values. The turbosupercharger with variable turbine geometry permits adaptation to the current engine operating point by adjustment of the turbine blades. As a result, a delayed response of the turbosupercharger can be avoided, and at the same time the degree of efficiency of the internal combustion engine can be improved. At the same time, a precisely regulated quantity of exhaust gas is fed into the high-pressure fresh air line via the exhaust gas feedback, as a result of which the emissions of nitrogen oxide are considerably reduced. This results in modern internal combustion engines having an air system that [sic] is defined by a high degree of internal coupling and strong non-linearity’s. Significant variables of the air system, for example pressure in the high-pressure exhaust gas line which is also calculated as an exhaust gas counterpressure P3, or the exhaust gas quantity MA which is fed back at a particular time, can only be determined with great expenditure in terms of measuring, or not at all. Corresponding sensors are not available, or are available only at very high cost. In contemporary systems, the sensor signals are used exclusively for the regulation of the air system. That is to say the air quantity signal relating to the air quantity ML21 which flows through the low-pressure fresh air line 108, is used only for controlling or regulating the position of the exhaust gas feedback valve 118. The measured supercharging pressure P2 is used only for influencing the actuator of the turbine 112. The system-induced cross couplings are not taken into account in contemporary systems and therefore act as an interference variable in the individual regulating circuits. With the method and device according to the invention, the known system dynamics are described approximately with models. Here, the real behaviour is abstracted in such a way that the remaining models can be calculated in the engine control unit in real time. Despite the simplification of the models, it is ensured here that the physical effects and couplings, essential for the regulation, between the individual systems are correctly represented. According to the invention, the physical relationships are greatly simplified. The inventive model of the entire air system which comprises a plurality of partial models can be used to carry out various tasks. Thus, for example signals of the air system which cannot be measured or signals of the air system which can only be measured with difficulty are calculated approximately from existing sensor data or manipulated variables. Existing sensor information can be logically linked in an optimum way and the measuring uncertainty thus reduced. The measured variables and the registered variables can be filtered without a loss of phase, that is to say without adverse effects on the dynamics. In the event of the failure of a sensor, a physically appropriate replacement value is available. Furthermore, functional structures can be greatly simplified by processing modeled variables which cannot be measured. For example, the supercharger can be monitored by evaluating the estimated rotational speed of the supercharger. Figure 2 illustrates the entire model by means of a block diagram. Essentially, the overall model contains various partial models for the individual components of the air system. A partial model for the compressor 106 is designated by 206. A partial model 202 which models the high-pressure fresh air line 102 is designated as a model high-pressure fresh air line. The charging air cooler is also included in the model compressor 206. A further partial model 200 models the internal combustion engine 100 and is also referred to as a cylinder model. A further partial model 212 is referred to as a turbine model and models the behaviour of the turbine 112. A further partial model 218 models the exhaust gas feedback and is also referred to as an exhaust gas feedback model 218. A further partial model 214 models the exhaust pipe 114 and is also referred to as a low-pressure exhaust gas line model. The input variables of the overall model are preferably the duty factor LTV which is applied to the supercharger actuator 113, the injected fuel quantity ME, the current engine rotational speed N, the duty factor ATV which is applied to the exhaust gas feedback actuator 118, the atmospheric pressure PI and the ambient air temperature Tl. These input variables are designated by small squares in Figure 2 . Instead of these variables, signals which characterize these variables can also be used. Thus, for example, instead of the injected fuel quantity, it is also possible to use the fuel quantity which is to be injected or a signal which indicates the injection period. Instead of the duty factors, it is possible, for example, to make direct use of the travel of the actuators. It is possible to use any variable calculated in the model as output variable if said variable is required in the control of the internal combustion engine. The use of the following output variables is particularly advantageous. These are the supercharging pressure P2 which corresponds to the pressure in the high-pressure fresh air line 102, the exhaust gas counterpressure P3 which corresponds to the pressure in the high-pressure exhaust gas line 110 between the turbine 112 and the internal combustion engine 100, the travel LH of the supercharger actuator 113 of the turbine 112, the rotational speed NL of the supercharger, the air mass flow rate ML21 via the compressor 106, the exhaust gas temperature T3 upstream of the turbine, the exhaust gas counterpressure P4 which corresponds to the pressure P4 in the exhaust pipe downstream of the turbine, the travel AH of the exhaust gas feedback actuator 118, the air mass flow rate MA via the exhaust gas feedback line 116, the oxygen content M031 after the combustion, and the oxygen content before the combustion M022. By simply converting, preferably using standardizing constants, it is possible to determine further signals which characterize the corresponding variables. Some of these variables which are determined by means of the model cannot be measured on the internal combustion engine, or can only be measured with large expenditure. For other variables such as, for example, the supercharging pressure P2, sensor signals are available. By comparing the measured variable and the variable which is calculated by means of the model, the model can be adjusted to the current situation. The output variables of the model or of the partial models are marked by circles or ellipses. Figure 3 illustrates in more detail the model of the compressor which also takes into account the properties of the supercharging air cooler. The compressor processes, as input variables, signals which characterize the different variables. These are the rotational speed NL of the supercharger, the ambient temperature Tl which corresponds to the temperature upstream of the compressor, the ambient pressure PI which corresponds to the pressure upstream of the compressor, and the supercharging pressure P2 which corresponds to the pressure downstream of the compressor. Various output variables are determined on the basis of these signals. These are essentially the mechanical power PL registered at the shaft 111, the supercharging air temperature T2 to which the temperature of the compressed gas downstream of the supercharging air cooler corresponds, and to the [sic] air guantity ML21 which flows through the compressor and through the intake line 108. The rotational speed NL of the supercharger is fed to a volume flow determining means 300. The ambient pressure PI is supplied to a density measuring means 310 and an enthalpy determining means 320. The supercharging pressure P2 is also fed to the enthalpy determining means 320. The ambient temperature Tl upstream of the compressor is fed to a temperature determining means 380, the enthalpy determining means 320 and the density determining means 310. The output signal of the volume flow determining means 300 and the output signal of the density determining means 310 are fed to a mass flow rate determining means 330 which determines the air mass flow rate ML21 as output signal. The output signal of the enthalpy determining means 320 is fed, on the one hand, to the volume determining means 300 and to an energy determining means 350. The output signal of the energy determining means 350 is applied to a power determining means 340 and a temperature determining means 360. In addition, the air mass flow rate ML21 is fed to the power determining means 340. The power determining means 340 supplies the signal PL relating to the mechanical power registered at the shaft. The temperature determining means 360 acts on the supercharging air cooler model 370 which in turn acts on the temperature determining means 380. The temperature determining means 380 determines the temperature signal T2. The volume flow rate which flows through the compressor is calculated as a function of the rotational speed of the supercharger and the enthalpy difference between the low pressure and the high pressure end, i.e. between the high-pressure fresh air line 102 and the low-pressure fresh air line 108. The enthalpy difference is made available by the enthalpy determining means 320. Here, the volume flow rate increases with the rotational speed of the supercharger and drops as the enthalpy difference increases. This relationship is simulated in the volume determining means 300 by means of a characteristic diagram or a calculation. The adaptation to specific properties of the compressor is then carried out by means of various constants. The density determining means 310 determines the density of the gas upstream of the compressor in the low-pressure fresh air line 108 on the basis of the pressure PI and the temperature Tl. The quantity determining means 330 determines by multiplying the volume flow rate by the density of the air mass flow rate ML21 via the compressor. The enthalpy determining means 320 determines the enthalpy difference of the gas upstream and downstream of the compressor as a function of the temperature Tl upstream of the compressor and the ratio between the pressure PI upstream of the compressor and the pressure P2 downstream of the compressor. In addition, various constants, such as the gas constant and the isotrope exponent, are taken into account. By dividing the enthalpy difference by the degree of efficiency of the compressor, the energy determining means 350 determines the energy which is fed to a certain quantity of compressed gas. The degree of efficiency of the compressor is preferably stored in a memory. In the power determining means 340, the energy is multiplied by the air mass flow rate ML21 flowing through the compressor. The mechanical power PL which is obtained instantaneously at the shaft results from this multiplication. The temperature determining means 360 calculates the energy supplied to the gas during the compression, this representing the heating of the gas in the compressor. A part of this heat is obtained from the gas again by means of the supercharging air cooler 104 . This takes into account the supercharging air cooler model 370. The proportion of the heat which is obtained from the gas is greater the higher the effectiveness of the supercharging air cooler. That is to say the temperature determined in the temperature determining means 360 is reduced as a function of the effectiveness of the supercharging air cooler. In the temperature determining means 380, at this temperature, by which the air in the compressor is heated, the temperature of the gas upstream of the compressor Tl is added, as a result of which the temperature T2 of the gas downstream of the compressor or downstream of the compressor and the supercharging air cooler is obtained. If the model is to be adapted to an engine without a supercharging air cooler, the effectiveness of the cooler is set to zero, i.e. the value zero is subtracted in the supercharging air cooler model 370. According to the invention, the air mass flow rate ML results from the density and the volume flow of the air which flows via the compressor. The density is determined from the temperature Tl and the pressure PI of the ambient air. The volume flow of the air results from the rotational speed of the supercharger and the enthalpy difference at the inlet and the outlet of the compressor. The enthalpy difference is calculated here from the pressure difference and the temperature Tl of the gas. This means that the compressor model determines the air mass flow rate ML21, which flows via the compressor, the supercharger power PI and the supercharger air temperature on the basis of the rotational speed NL of the supercharger, the ambient pressure PI, the supercharger pressure P2 and the ambient temperature Tl. It is particularly advantageous that only the temperature Tl and the pressure PI are measured by means of sensors, and the other variables are determined by means of other models. In Figure 4, the partial model for the high-pressure fresh air line, i.e. the model for the intake line 102, is illustrated as a block diagram. The feed line between the compressor 106 and the inlet valve into the cylinder is modelled as a container in which the status variables of the gas are linked by means of the ideal gas equation. The flow rate of the fresh air and all the resulting effects are neglected in favour of the simplicity of the model. The air quantity ML21 which flows out of the compressor, the supercharging air temperature T2 of the gas downstream of the supercharging air cooler 104, the air quantity ML22 which flows into the internal combustion engine, the air quantity MA which is fed back exhaust gas [sic] into the high-pressure fresh air line 102, the temperature TA in the exhaust gas feedback which corresponds to the temperature of the fed-back exhaust gas and the oxygen content MOA in the fed-back exhaust gas are preferably used as input variables for this model. On the basis of these input variables, the output variables are calculated by means of physically motivated logic operations. The supercharging pressure P2 in the high-pressure fresh air line 102, the supercharging air pressure T2 in the high-pressure fresh air line and the oxygen content M02 of the air fed back to the internal combustion engine are determined as output variables. The partial model for the high-pressure fresh air line 102 contains essentially an oxygen quantity determining means 400, a pressure determining means 410, a temperature determining means 420 and an integration means 432 which determines the overall mass. The oxygen quantity determining means 400 contains essentially a first oxygen quantity determining means 402, a second oxygen quantity determining means 404 and a third oxygen quantity determining means 406 whose output signals are summed with appropriate signs by a summing element 408 and then integrated by an integration means 409. The air quantity ML22 which corresponds to the air quantity which is fed into the internal combustion engine and the oxygen content M022 of the air which is fed into the internal combustion engine are fed to the first oxygen quantity determining means. The signal ML21 relating to the air quantity supplied by the compressor is fed to the second oxygen quantity determining means 404. The signal MOA relating to the oxygen content in the exhaust gas feedback line and the signal MA relating to the air quantity flowing in the exhaust gas feedback line are fed to the third oxygen quantity determining means. By multiplying the respective air quantity by the oxygen contents, the first, second and third oxygen quantity determining means determine the oxygen quantities of the respective air quantities. The second oxygen quantity determining means multiplies the air quantity ML21 by a fixed factor which corresponds to the oxygen content in the normal ambient air. The various oxygen quantities are integrated with the correct signs, i.e. the inflowing quantities with a positive sign and the outflowing quantities with a negative sign. The air quantities which flow into the high-pressure fresh air line 102 and out of it are also integrated with the correct signs by the adding element 430 and the integrator 432. The instantaneous overall air quantity in the container is obtained from this. On the basis of this overall air quantity in the container and the oxygen content, high-pressure fresh air line 102 which is determined by the oxygen quantity determining means 400, the oxygen content M022 of the air quantity flowing into the internal combustion engine is obtained. The change in the partial pressures in the high-pressure fresh air line 102 is calculated from the individual quantity flows of the respective temperature, the volume and the gas constant R. The first partial pressure determining means 412 calculates the partial pressure on the basis of the air quantity ML21 which flows in through the compressor 106 and the temperature T2 downstream of the supercharging air cooler 104. The second partial pressure determining means 414 determines the partial pressure on the basis of the air quantity ML22 which flows into the internal combustion engine, and the temperature T22 which corresponds to the temperature of the air quantity directly upstream of the internal combustion engine. This temperature is also referred to as mixing temperature T22. The third partial pressure determining means 416 determines the partial pressure on the basis of the air quantity MA which flows through the exhaust gas feedback line 116, and the temperature TA in the exhaust gas feedback line. The partial pressure calculations are preferably embodied as calculations which calculate the variables on the basis of the input variables in accordance with a formula. As the air quantity increases and/or the temperature rises, the partial pressure respectively increases. The changes in the partial pressures are added with the correct signs by the summing element 418. The inflowing proportions are included with a positive sign and the outflowing proportions are included with a negative sign. This results in the change in the air pressure P2 in the high-pressure fresh air line. The current supercharging pressure P2 is obtained by integrating the change in pressure over time. The temperature determining means 420 directly determines the mixing temperature T22 by means of the ideal gas equation using the gas constant R on the basis of the pressure P2 which is determined in this way in the high-pressure fresh air line, which was calculated as described above, and the gas quantity calculated by the integrator 432. The model of the high-pressure fresh air line determines the supercharging pressure P2, the oxygen content M022, of the gas which flows into the internal combustion engine, and the mixing temperature T22 on the basis of the air quantities ML21, ML22 and MA and their oxygen contents which flow into or out of the high-pressure fresh air line, the supercharging air temperature T2 and the temperature TA in the exhaust gas feedback line. The oxygen content M022 in the air quantity ML22 which flows into the internal combustion engine is obtained according to the invention from the air quantity ML22, the air quantity ML21 which flows via the compressor, the air quantity MA which flows in the exhaust gas feedback line, the respective oxygen contents and various constants. The supercharging pressure P2 is preferably obtained by integrating the absolute values for the change in pressure which are caused by the inflowing and outflowing air quantities and their temperatures. It is particularly advantageous if only the supercharging air temperature T2 is measured by means of a sensor and the other variables are determined by means of other models. In one particularly advantageous refinement, the supercharging air temperature is determined by means of the compressor model. The cylinder model 200 is illustrated in more detail in Figure 5. Signals are fed as input variables to the cylinder model 200. These are a signal ME which characterizes the fuel quantity which is to be injected or the injected fuel quantity, the mixing temperature T22, this is the temperature of the air which is fed to the cylinder, the supercharging pressure P2 which corresponds to the pressure upstream of the cylinder, the rotational speed N of the internal combustion engine, and the oxygen content M022 of the air which is fed to the internal combustion engine. The model supplies, as output variables, various signals which characterize the following variables. These are the exhaust gas temperature T3, this signal characterizes the temperature of the gas in the high-pressure exhaust gas line 110, the air quantity ML31 which flows out of the internal combustion engine into the high-pressure exhaust gas line 110, the air quantity ML22 which flows into the internal combustion engine, and the oxygen content M03I, [sic] of the air quantity ML31 which flows out of the internal combustion engine. The fuel quantity ME to be injected is fed, on the one hand, to a heating determining means 500, to an addition point 510, with a negative sign to an addition point 520, and to a multiplication point 530. The mixing temperature T22 is fed, on the one hand, to an intake quantity calculating means 540 and, on the other hand, to an addition point 550. The supercharging pressure P2 is fed to the intake quantity calculating means 540. The rotational speed signal N is fed, on the one hand, to a filling level correction means 560 and, on the other hand, to a multiplication point 570. The oxygen content M022 is fed to a logic operation point 580. The output signals of the filling level correction means 560 and of the intake quantity calculation means 540 are fed to a multiplication point 590 which in turn acts on the addition point 510, the multiplication point 570 and the multiplication point 580. The addition point 550 makes available the exhaust gas temperature T3. The output signal of the multiplication point 530 and the output signal of the multiplication point 570 are fed to an addition point 595 which makes available the air quantity ML31. The air quantity ML22 is present at the output of the multiplication point 570. The oxygen content M031 forms the output signal of a multiplication point 585 which divides the output signal of the addition point 520 by the output signal of the addition point 510. Given a known piston capacity of the internal combustion engine, the intake quantity calculating means 540 calculates the theoretically possible gas quantity in the cylinder from the supercharging pressure P2 and the mixing temperature T2, the fresh air flowing into the internal combustion engine, using the ideal gas equation. Said gas quantity rises proportionally to the supercharging pressure P2 and drops if the temperature of the air rises. This theoretical cylinder supercharge is corrected by means of the current rotational speed N on the basis of the signal of the supercharge correction 560 in the multiplication point 590, as a result of which the dynamic effects are taken into account when the cylinder is filled. From the gas quantity which is acquired in this way per stroke and the rotational speed N, the logic operation point 570 calculates the air quantity ML22 which flows into the internal combustion engine, preferably by multiplying the two variables and/or by means of a multiplication with various constants. The air quantity ML31 which corresponds to the exhaust gas mass flow rate is obtained by addition from the air quantity ML22 which flows into the internal combustion engine, and the fuel mass flow rate at the logic operation point 595. The fuel mass flow rate is determined by logically linking the fuel quantity ME to be injected and the rotational speed N at the logic operation point 530. For this purpose, the two signals are multiplied by one another and by various constants. The heating determining means 500 calculates the heating of the cylinder supercharge as a function of the injected fuel quantity ME and the gas quantity in the cylinder. The more fuel is injected, and the less gas there is in the cylinder, the greater the heating. The engine-specific relationship between the injected fuel quantity ME and the heat supplied to the gas is taken into account by means of a characteristic diagram. The exhaust gas temperature T3 is then obtained by addition at the addition point 550 of the output signal of the heating determining means 500 and the temperature of the supercharging air temperature T2. The overall gas quantity in the cylinder is obtained by adding the fuel quantity to be injected and the gas quantity per stroke, which is made available at the addition point 510 by the logic operation point 590. The logic operation point 590 calculates the oxygen content in the cylinder upstream of the combustion from the oxygen content M022 of the air quantity fed to the cylinder, and the overall gas quantity which corresponds to the output signal to the logic operation point 590 [sic] . In a first approximation, the oxygen content obtained from the cylinder supercharge is proportional to the injected fuel quantity ME. The oxygen quantity after the combustion is obtained by subtracting this oxygen quantity which is dependent on the fuel quantity from the oxygen quantity in the cylinder before the combustion, at the logic operation point 520. The oxygen quantity after the combustion is thus present at the output of the logic operation point 520. The oxygen content M031 after the combustion is obtained by forming, at the logic operation point 585, the ratio between this oxygen quantity and the overall gas quantity which corresponds to the output signal of the logic operation point 510. According to the invention, the exhaust gas temperature T3 is determined on the basis of the fuel quantity ME to be injected and the mixing temperature T22. The mixing temperature corresponds to the temperature of the gas which flows into the internal combustion engine. The exhaust gas temperature corresponds to the temperature of the gas which leaves the internal combustion engine. In addition, the air quantities ML22 and ML31 which flow into the internal combustion engine and which flow out of the internal combustion engine are calculated on the basis of the mixing temperature T22 and the supercharging pressure P2 of the gas flowing into the internal combustion engine, the rotational speed N of the internal combustion engine and the fuel quantity ME to be injected. This calculation is carried out essentially by virtue of the fact that various quantity variables are calculated on the basis of the temperature, pressure, fuel quantity, rotational speed and known constants, and are then suitably logically linked to one another. Figure 6 illustrates the turbine model 212 in more detail. In the model illustrated here, a turbine with variable geometry is modelled. Preferably, different signals which characterize the following operational variables are used as the input variables. These are the air quantity ML32 which flows via the turbine, the pressure P4 in the exhaust pipe 114, a signal which characterizes the pressure downstream of the turbine, the exhaust gas temperature T3 which characterizes the gas temperature upstream of the turbine, the supercharger travel which characterizes the position of the blades, and a power PL which is registered at the shaft 111 and characterizes the mechanical power taken up by the supercharger. Different output variables are obtained by suitably logically linking these variables and taking into account various physical and system-specific constants. These are the exhaust gas pressure P3 which characterizes the pressure upstream of the turbine, the temperature T4 in the exhaust pipe, that is to say downstream of the turbine, and the rotational speed NL of the supercharger. The supercharger travel LH, the air quantity ML32 via the turbine, the pressure P4 in the exhaust pipe and the exhaust gas temperature T3 are fed to a pressure determining means 600. The exhaust gas pressure P3 is present at the output of the pressure determining means 600. The pressure upstream of the turbine which corresponds to the exhaust gas pressure P3, and the pressure downstream of the turbine which corresponds to the pressure P4, as well as the exhaust gas temperature T3 are fed to an enthalpy difference determining means 610. Its output signal is fed to a rotational speed of the supercharger determining means 620 which additionally processes the air quantity ML32 via the turbine and the supercharger power PL. The supercharger rotational-speed determining means 520 supplies the rotational speed of the supercharger NL as output variable. The air quantity ML32 which flows via the turbine, and the output signal of the enthalpy difference determining means 610, are fed to a temperature determining means 630 which makes available the temperature T4 as the output signal in the exhaust pipe. The position of the blades is preferably converted into an effective cross-sectional area by means of a characteristic curve on the basis of the supercharger travel LH which characterizes the position of the blades of the turbine. Here, an opened position of the blades corresponds to a large area. Given a known effective area, the pressure upstream of the turbine P3 is calculated by means of the pressure determining means 600 on the basis of the air quantity 32, the pressure P4 downstream of the turbine, the temperature T3 upstream of the turbine and various physical constants. These calculations are carried out in the pressure determining means 600 using a formula. An increase in the mass flow rate, the temperature T3 upstream of the turbine and the pressure P4 downstream of the turbine leads in each case to an increase in the pressure P3 upstream of the turbine. A relatively large effective cross section leads, on the other hand, to a reduction in the pressure P3 upstream of the turbine. On the basis of the pressure upstream of the turbine P3, the pressure downstream of the turbine P4, the temperature P3 upstream of the turbine and various physical constants, the enthalpy difference determining means 610 determines the enthalpy difference of the gas upstream and downstream of the turbine. That is to say it determines the energy difference per gas quantity. The enthalpy difference grows with the pressure ratio between the pressure upstream and the pressure downstream of the turbine and with the temperature upstream of the turbine. The power which is acquired instantaneously in the turbine is obtained as a product of the enthalpy difference, the turbine efficiency and the air quantity ML32 via the turbine. The difference between the turbine power and supercharger power leads to a change in the rotation energy of the shaft 111, i.e. to a rise or fall in the angular speed, and thus in the rotational speed NL of the supercharger. This is converted into the revolution or the rotational speed of the supercharger by means of a suitable factor. On the basis of this variable, the rotational speed of the supercharger determining means 620 calculates the rotational speed NL of the supercharger. The turbine efficiency of the supercharger is preferably assumed here as a constant variable or can are [sic] stored in a characteristic diagram. From the enthalpy difference and the turbine efficiency, the temperature determining means determines the energy acquired from the gas. By means of physical constants, the energy acquired is logically linked directly to the temperature difference upstream and downstream of the turbine. On the basis of the temperature T3 upstream of the turbine and this temperature difference, the cooling determining means 630 determines the temperature T4 downstream of the turbine. According to the invention, the exhaust gas pressure P3 is determined on the basis of the supercharger travel LH, the air quantity ML32 which flows via the turbine, the pressure P4 downstream of the turbine and the exhaust gas temperature T3. The enthalpy difference across the turbine is determined on the basis of the pressure difference across the turbine which is calculated from the exhaust gas pressure P3 and the pressure P4 downstream of the turbine, and the exhaust gas temperature. The temperature T4 in the exhaust pipe is calculated on the basis of the enthalpy difference and the exhaust gas temperature T3. The rotational speed of the supercharger is determined on the basis of the enthalpy difference, the supercharger power PL and the air quantity ML32 which flows via the turbine. The model of the exhaust pipe, i.e. of the low-pressure exhaust gas line 114, is illustrated in Figure 7. This model determines the pressure P4 downstream of the turbine on the basis of the air quantity ML32 via the turbine, the ambient pressure PI and the temperature T4 downstream of the turbine in the exhaust pipe. The model of the exhaust gas tract 214 is used to model the effects of the exhaust gas tract on the pressure downstream of the turbine. The entire exhaust gas tract is modelled as a spatially concentrated orifice. On the basis of the effective orifice area, the model 214 determines the pressure P4 downstream of the turbine, which pressure corresponds to the pressure above the orifice, on the basis of the air quantity iyiL32, the ambient pressure PI which corresponds to the pressure below the orifice, the temperature T4 above the orifice and two material constants. Here, the pressure P4 downstream of the turbine rises as the air quantity ML32 increases, the atmospheric pressure PI increases and the temperature T4 increases downstream of the turbine. A greater effective area brings about a drop in the pressure downstream of the turbine. The effective orifice area is preferably considered as a constant. In Figure 8, the exhaust gas feedback model 218 is represented in more detail. The exhaust gas feedback model takes into account the changes in the air system when part of the exhaust gas is fed back into the intake tract. The exhaust gas feedback model 218 takes into account signals as input signals. These are the exhaust gas pressure P3 which characterizes the pressure in the high-pressure exhaust gas line, the exhaust gas temperature T3, the supercharging pressure P2, the supercharging air temperature T2 and the exhaust gas feedback travel AH which characterizes the travel of the exhaust gas feedback valve 118. The output variables are determined on the basis of these variables by means of the application of a suitable logic operation. These output variables are in particular the air quantity MA which flows via the exhaust gas feedback valve 118, and the temperature TA which characterizes the temperature of the exhaust gas just before mixing with the fresh gas. The supercharging pressure P2 and the exhaust gas pressure P3 which characterize the pressure difference across the exhaust gas feedback valve are fed to a switch-over means 805. All the signals, with the exception of the supercharging air temperature T2, are fed to a first quantity determining means 800. All the signals, with the exception of the exhaust gas temperature T3, are fed to a second quantity determining means 810. The exhaust gas temperature T3 and the supercharging air temperature T3 are fed to the first input 831 and to the second input 832 of a second switch-over means 830. The output signal of the first quantity determining means 800 is fed to the first input 821, and the output signal 810 is fed via a sign reversing means 850 to the second input 822 of a first switch-over means 820. The air quantity MA which flows via the exhaust gas feedback valve is present at the output of the first switch-over means. The temperature TA is present in the exhaust gas feedback line at the output of the second switch-over means 830. The two switching means 820 and 830 are actuated as a function of the output signal of the switch-over means 805. The quantity determining means 800 and 810 determine the air quantity MA which flows via the exhaust gas feedback valve, preferably by means of a throttle equation. The air quantity MA which flows via the exhaust gas feedback valve depends essentially on the pressure and the temperature upstream of the exhaust gas feedback valve, and the pressure downstream of the exhaust gas feedback valve and the effective area of the exhaust gas feedback valve. Here, the air quantity rises as the pressure difference rises and the effective area increases. It drops as the temperature upstream of the valve rises. The direction of the mass flow rate via the exhaust gas feedback valve depends on whether the exhaust gas pressure P3 in the high-pressure exhaust gas line is higher or lower than the supercharging pressure P2 in the high-pressure fresh air line. For this reason, two quantity determining means are provided. Which of the two means predefines the air quantity is determined by the position of the switching means 820. The position of the switching means 820 depends on the pressure difference across the exhaust gas feedback valve. The temperature TA which prevails in the exhaust gas feedback line is dependent on this pressure difference, and thus also on the direction of flow. The effective area of the throttle is a function of the exhaust gas feedback travel AH of the exhaust gas feedback valve and is preferably taken into account in the form of a characteristic curve which can be applied. If the exhaust gas pressure P3 is higher than the supercharging pressure P2, the output signal of the first quantity determining means is used as an air quantity MA, and the exhaust gas temperature T3 is used as a temperature TA. This corresponds to the position of the switching means illustrated in Figure 8 . If, on the other hand, the supercharging pressure P2 is higher than the exhaust gas pressure P3, the switching means are placed in the position which is not shown, and the output signal of the second quantity determining means 810 determines the air quantity MA, and the temperature TA corresponds to the supercharging air temperature T2, respectively. According to the invention, the air quantity MA which flows through the exhaust gas feedback valve is obtained on the basis of the pressure difference across the exhaust gas feedback valve, the temperature of the air which flows via the exhaust gas feedback valve, and the exhaust gas feedback travel AH. The pressure difference is calculated on the basis of the exhaust gas pressure P3 and the supercharging pressure P2. Either the supercharging air temperature T2 or the exhaust gas temperature T3 is used as the temperature of the air in the exhaust gas feedback line as a function of the pressure difference. The control of the exhaust gas feedback can be significantly improved if a signal which characterizes the air quantity which flows via the exhaust gas feedback valve is present. A sensor which supplies such a signal is difficult to implement because it is subject, by virtue of its position in the exhaust gas mass flow, to very high temperatures and a high degree of contamination. An indirect procedure is selected in contemporary systems. Here, a pneumatically actuated exhaust gas feedback valve is opened or closed until the air quantity ML21 measured by means of a sensor reaches its reference value. The fed-back exhaust gas quantity is obtained from the difference between the air quantity ML22 which flows into the internal combustion engine, and the air quantity ML21 which flows via the compressor. This procedure has two essential disadvantages: when the fed-back exhaust gas quantities are small, the tolerances of the sensor for registering the air quantity lead to very large faults in the exhaust gas feedback rate. The control loop for the exhaust gas feedback valve contains a large number of partially inert components so that the dynamics remain restricted. Both effects, i.e. large tolerances and inadequate dynamics, lead to degraded exhaust gas values. In exhaust gas feedback actuators with an integrated displacement sensor, the position of the valve is adjusted very quickly and precisely with a subordinate control loop. In the electrical exhaust gas feedback valve, the necessary force is generated by an electromagnet. When there is subordinate position control, the current position of the valve is measured by means of a displacement sensor, and the current is varied until the valve has assumed the desired position. In this final position, the current is a measure of the necessary holding force. This depends essentially on the pressure difference upstream/downstream of the valve. The current through the coil is a measurement signal for the pressure difference across the exhaust gas feedback valve. The mass flow rate, standardized to the temperature, via the valve is calculated on the basis of the known valve geometry, the exhaust gas feedback travel and the pressure difference. The valve geometry is determined structurally. The travel is obtained from the integrated displacement sensor. The pressure difference is derived from the coil current. The current signal which is present in a position-controlled electric exhaust gas feedback valve is used to determine the pressure difference across the exhaust gas feedback valve. The temperature-standardized air quantity MA which flows via the exhaust gas feedback valve can be determined from the supercharging pressure P2, the pressure difference, the exhaust gas feedback travel AH and the valve geometry. According to the invention, this value is used as an actual value in a subordinate control loop for the air quantity MA. As a result, the temperature-standardized air quantity which flows via the exhaust gas feedback valve can be set quickly and precisely. By directly measuring the air quantity MA, relatively small tolerances can be implemented in the control of the exhaust gas feedback rate. The subordinate regulation of the standardized air quantity MA makes it possible to achieve a significant improvement in the dynamics. A gas force FP acts on the exhaust gas feedback valve as a result of the pressure difference between the high-pressure exhaust gas line and the high-pressure fresh air line. In order to hold the valve, this force must be compensated by the force of the electromagnet FM. This force depends directly on the current through the magnet !„. This yields the measurement equation for the pressure difference: P3-P2=fi (FM) =f2 (AH, I„; The non-linear relationship f^ is determined by measurement on a suitable test device. The current pressure difference is determined on the basis of the known relationship £2, the travel AH and the current I^n through the electromagnet. The temperature-standardized mass flow rate across a valve is obtained according to the through-flow equation as: I— fP3^ MA„„^^ = MA^T3 = A(AH)P3_ y^ \p2j in which: MAnorm is the temperature-standardized mass flow rate MA is the mass flow rate P2 is the supercharging pressure P3 is the exhaust gas pressure T3 is the exhaust gas temperature A(AH) is the throttle coefficient I// is the through-flow function. The variation in the throttle coefficient as a function of the travel, and the precise profile of the through-flow function must be determined in advance by measurement on a suitable test device. The temperature-standardized air quantity is calculated by means of the above equation. The air quantity MA which flows via the exhaust gas feedback valve is determined from the temperature-standardized air quantity together with a measured or estimated value for the exhaust gas temperature T3. This calculation is carried out for example in the quantity determining means 800 and 810. The other partial models are not absolutely necessary for this procedure. Thus, the supercharging pressure can be measured directly, and the exhaust gas pressure P3 can be determined on the basis of the pressure difference and the supercharging pressure P2. The pressure difference is preferably determined here from the exhaust gas feedback travel AH and the current which flows through the valve. The supercharger travel LH is determined in the block 213 on the basis of the duty factor LTV for the supercharger. The corresponding conversion of the actuation signal ATV for the exhaust gas feedback valve into the exhaust gas feedback travel AH of the exhaust gas feedback valve is carried out in the block 219 in Figure 2. The block 213 and the block 219 are of similar construction in terms of their design. The two blocks differ only in the method of conversion. Essentially, it is composed of a characteristic diagram or a conversion means which converts the respective duty factor LTV or ATV into a travel value. In a first step, the duty factor is limited to a physically appropriate value between 0% and 100%. The dynamics of the electropneumatic converter are asymmetrical, i.e. the travel of the actuator moves significantly more quickly in one direction than in the other direction. This is modelled by means of an asymmetrical first-order time-delay element. That is to say different time constants are active for rising and falling output variables AH or LH. The output of the first-order time-delay element is used as an input variable of a characteristic curve to be applied. Here, the delayed duty factor is converted into a relative travel between 0 and 100%. This travel LH or AH is then used as an input variable of the various models. WE CLAIM : 1. A method for controlling an internal combustion engine having an air system, in which at least one variable which characterizes the air system is determined by means of at least one model on the basis of at least one control variable and at least one measured variable which characterizes the state of the ambient air characterized in that the model comprises at least a first submodel and a second submodel, output variables being determined on the basis of input variables by means of a submodel, in that in addition to at least one output variable from a second submodel, the control variable and the measured variable are also taken into account as input variables for the first submodel, at least one variable which characterizes the quantity of fuel to be injected being taken into account as control variable. 2. The method as claimed in claim 1, wherein a fuel quantity (ME) which characterizes the quantity of fuel to be injected, an exhaust-gas recirculation duty factor (ATV), which characterizes the actuation signal for an actuator for influencing the exhaust-gas recirculation, or a supercharger duty factor (LTV), which characterizes the actuation signal for an actuator for influencing the characteristic of a supercharger, is used as control variable. 3. The method as claimed in claims 1 or 2, wherein at least one engine speed variable (N), which characterizes, the speed of the internal combustion engine, an ambient temperature (Tl), which characterizes the temperature of the ambient air, or an ambient pressure (PI), which characterizes the pressure of the ambient air, is used as measured variable. 4. The method as claimed in claim 1, wherein a compressor model (206) determines at least the quantity of air (ML21) which flows across the compressor, the supercharger power (PL) and the charge-air temperature (T2) on the basis of at least the supercharger rotational speed (NL), the ambient pressure (PI), the boost pressure and the ambient temperature (Tl). 5. The method as claimed in claim 4, wherein the quantity of air (ML21) is determined on the basis of the density and volume of the air which flows across the compressor, the density being determined from the ambient temperature (Tl) and the ambient pressure (PI) and the volume being determined from the supercharger rotational speed (NL) and an enthalpy difference, the enthalpy difference being determined from the ambient pressure (PI) and the boost pressure (P2). 6. The method as claimed in claim 1, wherein a high-pressure fresh air line model determines at least the boost pressure (P2), the oxygen content (M022), the quantity of air which flows into the internal combustion engine and the mixing temperature (T22) on the basis of at least the quantities of air (ML21, ML22 and MA) flowing into a high-pressure fresh air line, the oxygen contents of these quantities of air, the charge air temperature (T2) and the temperature (TA) in the exhaust-gas recirculation line. 7. The method as claimed in claim 6, wherein the oxygen content (M022) which flows into the internal combustion engine is determined on the basis of the quantities of air (ML21, ML22 and MA) which flow into the high-pressure fresh air line and the oxygen contents of these quantities of air and at least one constant, or in that the boost pressure (P2) is determined through integration of the contributions of pressure changes which are predetermined on the basis of the quantities of air flowing in or out and the temperatures of these quantities of air. 8. The method as claimed in claim 1, wherein a cylinder model calculates at least the exhaust-gas temperature (T3), the quantity of air (ML22) which flows into the internal combustion engine and the quantity of air (ML31) which flows out of the internal combustion engine, as well as the oxygen content (M031) thereof, on the basis of at least the fuel quantity (ME), the engine speed (N), the boost pressure (P2), the mixing temperature (T22) and the oxygen content (M022) of the air which flows into the internal combustion engine. 9. The method as claimed in claim 8, wherein the exhaust-gas temperature (T3) is determined on the basis of the fuel quantity (ME) and the mixing temperature (T22), or in that the quantities of air (ML22 and ML31) which flow into the internal combustion engine and out of the internal combustion engine are determined on the basis of the temperature (T22) and pressure (P2) of the gas flowing into the internal combustion engine, the engine speed (N) or the fuel quantity (ME). 10. The method as claimed in claim 1, wherein a turbine model determines at least the exhaust-gas pressure (P3), the supercharger rotational speed (NL) and the temperature (T4) downstream of the turbine on the basis of at least the supercharger travel, the exhaust-gas temperature (T3), the pressure (P4) downstream of the turbine, and the quantity of air (ML32), which flows across the turbine. 11. The method as claimed in claim 10, wherein the exhaust-gas pressure (P3) is determined on the basis of the supercharger travel (LH), the quantity of air (ML32) which flows across the turbine, the pressure (P4) down- stream of the turbine and the exhaust-gas temperature (T3), or in that the enthalpy difference across the turbine is determined on the basis of the pressure difference across the turbine, which is calculated from the exhaust-gas pressure (P3) and the pressure (P4) downstream of the turbine, and the exhaust-gas temperature, of the enthalpy difference and the exhaust-gas temperature (T3), or in that the supercharger rotational speed is determined on the basis of the enthalpy difference, the supercharger power (PL) and the quantity of air (ML32) which flows across the turbine. 12. The method as claimed in claim 10, wherein the exhaust-gas pressure (P3) is determined on the basis of the supercharger travel (LH), the quantity of air (ML32) which flows across the turbine, the pressure (P4) down- stream of the turbine and the exhaust-gas temperature (T3), or in that the enthalpy difference across the turbine is determined on the basis of the pressure difference across the turbine and the exhaust-gas temperature (T3), or in that the temperature (T4) downstream of the turbine is determined on the basis of the enthalpy difference and the exhaust-gas temperature (T3), or in that the supercharger rotational speed is determined on the basis of the enthalpy difference, the supercharger power (PL) and the quantity of air (ML32) which flows across the turbine. 13. The method as claimed in claim 1, wherein an exhaust pipe model determines the pressure downstream of the turbine on the basis of at least the quantity of air (ML32), which flows across the turbine, the ambient pressure (PI) and the temperature (T4) downstream of the turbine. 14. The method as claimed in claim 1, wherein an exhaust-gas recirculation model determines the temperature (TA) and the quantity of air (MA) which flows through the exhaust-gas recirculation line on the basis of the exhaust-gas recirculation travel (AH), the temperature (T2, T3) and the pressure (P2, P3) upstream and down- stream of the exhaust-gas recirculation valve. 15. The method as claimed in claim 14, wherein the quantity of air (MA) which flows through the exhaust gas recirculation valve is determined on the basis of the pressure difference across the exhaust-gas recirculation valve, the temperature of the air which flows across the exhaust gas recirculation valve and the exhaust gas recirculation travel (AH), the charge-air temperature (T2) or the exhaust gas temperature (T3) being used as the temperature of the air in the exhaust gas recirculation line as a function of the pressure difference across the exhaust gas recirculation valve.

Documents:

in-pct-2002-1138-che abstract-duplicate.pdf

in-pct-2002-1138-che abstract.jpg

in-pct-2002-1138-che claims-duplicate.pdf

in-pct-2002-1138-che claims.pdf

in-pct-2002-1138-che correspondences-others.pdf

in-pct-2002-1138-che correspondences-po.pdf

in-pct-2002-1138-che description (complete)-duplicate.pdf

in-pct-2002-1138-che description (complete).pdf

in-pct-2002-1138-che drawings-duplicate.pdf

in-pct-2002-1138-che drawings.pdf

in-pct-2002-1138-che form-1.pdf

in-pct-2002-1138-che form-19.pdf

in-pct-2002-1138-che form-26.pdf

in-pct-2002-1138-che form-3.pdf

in-pct-2002-1138-che form-5.pdf

in-pct-2002-1138-che others.pdf

in-pct-2002-1138-che pct.pdf

in-pct-2002-1138-che petition.pdf