EP2262995A1

EP2262995A1 - Method and device for operating an internal combustion engine having a mass flow line

Info

Publication number: EP2262995A1
Application number: EP08873232A
Authority: EP
Inventors: Sabine Wegener; Lutz Reuschenbach; Patrick Menold; Kristina Milos; Michael Drung
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2008-03-10
Filing date: 2008-11-27
Publication date: 2010-12-22
Also published as: CN101965444A; US20110048375A1; CN101965444B; WO2009112108A1; DE102008000581A1; US8746212B2

Abstract

A method and a device (15) for operating an internal combustion engine (1) having a mass flow line (5) are proposed, which allow to the actual fill level to track the target fill level of the internal combustion engine with desired dynamics. A mass flow is supplied to the internal combustion engine (1) via the mass flow line (5). A target value is specified for a variable that is characteristic for the mass flow rate to the internal combustion engine (1). The target value of the variable characteristic for the mass flow rate is formed, starting from a balance of the mass flow flowing into the mass flow line (5) and the mass flow flowing out of the mass flow line (5), according to a specified time progression.

Description

description

title

Method and device for operating an internal combustion engine with a mass flow line

State of the art

The invention is based on a method and a device for operating an internal combustion engine with a mass flow line according to the preamble of the independent claims.

For example, from DE 10 2005 007 057 Al a filling control is known, which seeks a dynamic accurate control. For this purpose, a value characteristic of the dynamic behavior of a parameter is determined. A filling of a cylinder can thus be set exactly. A corresponding air model can be used to determine, based on the current setting values together with pressure, temperature and mixture state in the intake manifold and the engine speed, the current or in the near future sucked air quantity. The inverted function can be used to selectively adjust the influencing variables of the sucked-in volume in order to set a quantity of air appropriate to the target value of the torque.

Advantages of the invention

The inventive method and the inventive device for

Operation of an internal combustion engine with a mass flow line with the features of the independent claims have the advantage that the desired value of the characteristic mass flow starting from a balance of the mass flow line in the flowing mass flow and the effluent from the mass flow line mass flow according to a pre given time course is formed. In this way, a desired output variable of the internal combustion engine, in particular in the case in which it changes abruptly, can nevertheless be converted according to a predetermined or desired dynamics by the predetermined time profile for the desired value of the variable characteristic for the mass flow. To this

In this way, an actual value of the variable characteristic of the mass flow, for example in the context of a control, can also follow the desired value with the desired dynamics.

The measures listed in the dependent claims are advantageous

Further developments and improvements of the method specified in the main claim possible.

It is advantageous if a setpoint value for this mass flow is selected as the desired value of the variable characteristic of the mass flow and if so

Setpoint value for the mass flow in the balance of the mass flow flowing into the mass flow line and the mass flow flowing out of the mass flow line of the mass flow flowing into the mass flow line is selected. In this way, the desired value of the characteristic variable for the mass flow can be formed in a particularly simple and inexpensive manner.

A further advantage results if the predefined time profile is selected as the time profile according to a proportional timer, preferably of the first order, with a predetermined time constant. In this way, the predetermined time profile for the desired value of the variable characteristic of the mass flow can be particularly simple and inexpensive to use in the balance of the flowing into the mass flow line mass flow and the effluent from the mass flow line mass flow without affecting this balance significantly in their accuracy becomes.

A further advantage results when a change over time of the mass in the mass flow line is formed as the difference between incoming mass flow and outflowing mass flow and if this relationship for determining the nominal value of the variable characteristic of the mass flow is resolved according to the inflowing mass flow and the temporal change the mass in the mass flow line is replaced by the predetermined time course. This represents a particularly simple and inexpensive implementation for determining the setpoint value of the variable characteristic of the mass flow in accordance with the predetermined time profile, which requires little calculation effort.

It is advantageous if the relationship for determining the desired value of the variable characteristic of the mass flow is resolved taking into account the ideal gas equation for the incoming mass flow, so that the time change of the mass in the mass flow line is converted into a temporal change of the pressure in the mass flow line if a setpoint value for the pressure is formed as a function of a desired output variable of the internal combustion engine and if the time change of the pressure is formed as a difference quotient of the difference between the setpoint value for the pressure and a current pressure per unit time. In this way, the desired output variable can be converted with the aid of the setpoint value of the variable characteristic of the mass flow according to the predetermined or desired time profile in a simple and less complicated manner.

Another advantage arises when the predetermined time constant is selected as the time unit. Thus, for the implementation of the desired output variable as a desired or predetermined time profile in a simple and inexpensive manner, the time profile according to the proportional time element can be specified.

It is furthermore advantageous if the predefined time profile with regard to a desired fuel consumption and / or a desired response and / or a desired reproducibility for setting a desired output variable of the internal combustion engine is determined by means of the desired value of the variable characteristic of the mass flow. In this way it is made possible by conversion of the desired output variable by means of the set value of the variable characteristic of the mass flow according to the predetermined time course of the fuel consumption and / or the response and / or a desired reproducibility for setting the ge desired output variable of the internal combustion engine can be optimized by means of the desired value of the variable characteristic of the mass flow.

drawing

An embodiment of the invention is illustrated in the drawing and explained in more detail in the following description. Show it:

Figure 1 is a schematic view of an internal combustion engine and

Figure 2 is a functional diagram for explaining the inventive

Device and the method according to the invention.

Description of the embodiment

In FIG. 1, 1 denotes an internal combustion engine which is designed, for example, as an Otto engine or as a diesel engine. In this case, the internal combustion engine 1 comprises one or more cylinders, one of which is shown by way of example in FIG. 1 and identified by the reference numeral 35. The cylinder 35 is supplied via an air supply 10 fresh air. The flow direction of

Fresh air in the air supply 10 is indicated in Figure 1 by arrows. In the air supply 10, an actuator, for example in the form of a throttle valve is arranged, is influenced by the position or opening degree of the air mass flow to the cylinder 35. The position or the degree of opening of the actuator 20 is set by a motor controller 15, for example, using a control circuit, not shown in Figure 1. In this case, an actual position of the actuator 20 of a desired position of the actuator 20 is tracked. The actual position can be detected, for example, by a position transmitter in the region of the actuator 20, for example in the form of a potentiometer, and forwarded to the motor control 15. Such a position transmitter is indicated in FIG. 1 by reference numeral 175. The desired position of the actuator 20 can be determined in the engine control 15, for example, depending on a nominal air mass flow to the cylinder 35, wherein the desired air mass flow, for example, depending on one or more coordinated requirements for a to be delivered by the internal combustion engine 1 torque or one of the engine 1 output power in the engine controller 15 can be determined. In the simplest case indicated in FIG. 1, the setpoint air mass flow is formed as a function of a driver desired torque FW, which is supplied to the engine control 15 by an accelerator pedal module 65. The accelerator pedal module 65 forms the driver's desired torque FW depending on the degree of actuation of an accelerator pedal of a vehicle driven by the internal combustion engine 1. The formation of the desired air mass flow will be described below with reference to the functional diagram according to FIG. Downstream of the throttle valve 20, the air supply 10 passes into a suction pipe 5, in which a Saugrohr- pressure sensor 45 and a Saugrohrtemperatursensor 50 are arranged. Of the

Intake manifold pressure sensor 45 measures the current intake pipe pressure ps and forwards the measured values to the engine control 15. The intake manifold temperature sensor 50 measures the current intake pipe temperature TS and forwards the measurements to the engine controller 15. Finally, the fresh air is sucked into a combustion chamber of the cylinder 35 via an inlet valve 25. The inlet valve 25 can be adjusted either by a camshaft or by electro-hydraulic or electro-mechanical valve control with respect to its opening time and its opening duration. In the example according to FIG. 1, it should be assumed that the opening time and opening duration of the inlet valve 25 are opened and closed by an inlet camshaft in a manner known to the person skilled in the art. The control of the opening time and opening duration of an exhaust valve 30 to the outlet of the formed during the combustion of air and fuel in the combustion chamber of the cylinder 35 exhaust gas into an exhaust line 40 in the same manner, in Figure 1 in turn driving the Auslassven- tils 30 by an exhaust camshaft with regard to the opening and closing of the exhaust valve 30 is to be assumed. The supply of fuel into the combustion chamber of the cylinder 35 is not shown in Figure 1 for reasons of clarity and can be done either directly or via the intake manifold 5 or via the air supply 10 by means of one or more suitable injectors. In the case of an Otto engine, a spark plug is also provided, which

/ Fuel mixture in the combustion chamber of the cylinder 35 ignites.

A camshaft sensor 70 in the region of the cylinder 35 or the intake or exhaust camshaft determines the current camshaft position in ⁰ NW and forwards the measured values to the engine control 15. Based on the current cam shaft position ⁰ NW of the intake or exhaust camshaft, the engine controller 15 can recognize in a manner known to those skilled in the art whether the intake valve 25 is currently open or closed and whether the exhaust valve 30 is currently open or closed. It can be concluded from the position of the intake camshaft and the opening state of the exhaust valve 30 due to a fixed relationship between the opening and closing times of the intake valve 25 and the exhaust valve 30 above the crank angle. Alternatively, a camshaft sensor for the intake camshaft and a camshaft sensor for the exhaust camshaft may be provided, respectively.

A speed sensor 55 in the region of the cylinder 35 or the crankshaft driven by the cylinder 35 determines the current engine speed n and forwards the measured values to the engine controller 15. An engine temperature sensor 60 measures the current engine temperature TM and forwards the measured values to the engine controller 15. In this case, the engine temperature sensor 60 may measure, for example, the cooling water temperature that is characteristic of the engine temperature.

According to the present invention, the determination of a setpoint value for a variable that is characteristic of the mass flow to the internal combustion engine 1 or to the cylinder 35 is possible, wherein this variable can be, for example, the air mass flow that flows via the actuator 20 into the intake manifold 5 accrues. In the following, it is to be assumed by way of example that the desired value for the mass flow flowing into the intake manifold 5 via the actuator 20 is determined as the desired value of the quantity characteristic for the mass flow. This determination is carried out in a control unit 20 of the motor controller 15, wherein the control unit 20 is shown in dashed lines in Figure 1.

An exemplary embodiment of the control unit 20 is explained below in FIG. 2 by means of a functional diagram.

The desired filling of the combustion chamber of the internal combustion engine 1 or of the cylinder 35 or the desired mass flow flowing out of the intake manifold 5 into the combustion chamber of the internal combustion engine 1 or the cylinder 35 changes during operation of the internal combustion engine 1, in particular at the start of operation. drove a vehicle by the internal combustion engine 1 constantly. The described control for the position of the actuator 20 ensures that the actual filling of the desired filling follows. The suction tube 5 and the type of control determine the dynamics with which the actual filling of the desired filling follows. If you z. B. the actuator 20 is adjusted so that the actual mass flow through the actuator 20 in the

Suction pipe 5 the desired mass flow into the combustion chamber of the cylinder or cylinder 35 from the suction pipe 5, the actual filling of the combustion chamber of the desired filling of the combustion chamber follows very slowly, since no additional mass flow for filling or no reduced mass flow for emptying the suction tube 5 is provided.

The same problems and tasks occur when z. B. in the air supply 10 a compressor with bypass line including bypass valve, followed by a throttle valve or alternatively a throttle, followed by a compressor with bypass line including bypass valve or other known in the art structure of various mass flow actuators for adjusting the flowing into the intake manifold 5 Mass flow provided and are responsible for the filling construction or degradation. In Figure 1, a throttle valve is shown as an example of such a mass flow controller. However, in FIG. 1, the actuator 20 is representative of one or more arbitrary mass flow controllers including their piping for setting a desired mass flow flowing to the intake manifold 5. The regulation of this, possibly of several components including piping existing actuator 20 ensures how the suction tube 5 empties or fills and what dynamics of the filling thus sets.

According to the invention, it is now provided to form a desired value for the mass flow flowing from the actuator 20 into the intake manifold 5 or for a variable characterizing this mass flow in accordance with a predetermined time profile, so that the actual charge of the combustion chamber is defined in accordance with the predetermined time profile Dynamics behaves. For this purpose, the desired value of the variable characteristic of the mass flow is formed on the basis of a balance of the mass flow flowing into the intake pipe 5 and the mass flow flowing out of the intake pipe 5 in accordance with the predetermined time profile. As desired value of the variable characteristic of the mass flow In the following, as already described above, the desired value for the mass flow flowing into the intake manifold 5 via the actuator 20 is selected.

In this case, the setpoint mass flow which is to flow from the actuator 20 into the intake manifold 5 is calculated from the nominal charge of the combustion chamber and the predetermined time course, taking into account the conditions prevailing in the intake manifold, in particular with respect to intake manifold pressure and intake manifold temperature. If the actuator 20 sets this desired mass flow within the scope of the described control, the desired dynamic for the filling also sets, i. H. the actual filling follows the desired filling according to the predetermined time course.

Based on the driver's desired torque FW and / or torque requirements of other systems, such. As a traction control system, an anti-lock braking system, a vehicle dynamics control, a vehicle speed control or the like, a resulting desired torque or a resulting desired power of the internal combustion engine 1 is determined in the art known manner. In the following, it is assumed by way of example that a resulting desired torque is determined. For the sake of simplicity and as shown in FIG. 1, it should be assumed by way of example and without limiting the generality for the description of the invention that the resulting setpoint torque corresponds to the driver's desired torque FW. From the resulting target torque, that is to say in the example described here, the driver's desired torque FW, the setpoint filling of the combustion chamber is calculated taking into account efficiencies and the engine speed n in a manner known to the person skilled in the art. It can also in the

Expert known manner, the driver's desired torque FW be previously prepared by impact absorption and / or one or more driveability filter. In spite of the optionally existing filtering by the load impact damping and / or the one or more drivability filters, the calculated desired filling can still be subjected to rapid changes, which the mass in the intake manifold 5 can not follow at will because of the intake manifold dynamics. The Istfülllung can not be tracked as fast as the desired filling. Therefore, according to the invention to be set by the actuator 20 target mass flow into the suction pipe 5 according to the predetermined time course can be specified so that the actual filling of the desired filling with the predetermined time course corresponding desired dynamics can follow.

FIG. 2 shows a functional diagram for explaining the control unit 20 according to the invention of the motor control 15. The functional diagram of the

FIG. 2 at the same time represents a flowchart which describes an exemplary sequence of the method according to the invention. The control unit 20 may, for example, be implemented in the engine control 15 in terms of software and / or hardware.

In the control unit 20, based on the balance of the inflowing into the intake manifold 5 mass flow and the effluent from the suction pipe 5 mass flow of the setpoint for the over the actuator 20 in the intake manifold 5 flowing mass flow is formed according to a predetermined time course. It is provided in this example that the predetermined time course is selected as a time course according to a proportional first-order timer with a predetermined time constant. Alternatively, another time profile can be specified, for example, a time course according to a proportional timer higher than first order with also predetermined time constant. In the present example, a time change of the mass in the intake manifold 5 is formed as the difference between the flowing into the intake manifold 5 mass flow and the effluent from the suction pipe 5 mass flow for the balance of the flowing into the suction pipe 5 mass flow and the outflowing from the suction pipe 5 mass flow. This situation is represented by the following differential equation for the intake manifold 5:

dm / dt = ms _to - ms _ab (1)

Here m is the mass in the intake manifold 5, dm / dt is the change over time of the mass in the intake manifold 5, ms _to the mass flow into the intake manifold 5 via the actuator 20 and rnS _g b of the mass flow flowing from the intake manifold 5 into the combustion chamber. According to the invention this relationship is _{to be} dissolved after the inflowing into the suction pipe 5 via the actuator 20 ms mass flow for determining the desired mass flow rate and the change in the mass dm / dt in the suction pipe 5 by the predetermined time profile according to the proportional Replaced first-order timer with the predetermined time constant. The on the actuator 20 in the suction pipe 5 flowing mass flow ms _to is then considered as a target mass flow, _which is to be adjusted by the actuator 20.

According to a development of the invention, it may then be provided that the relationship formed by the differential equation (1) for determining the desired mass flow ms is _to be taken into account taking into account the ideal gas equation:

ps * VS = m * R * TS (2)

after the mass flow ms flowing into the intake manifold 5 via the actuator 20 _, and thus after the desired mass flow, so that the time change of the mass dm / dt in the intake manifold 5 is converted into a temporal change dps / dt of the intake manifold pressure. In the ideal gas equation (2) VS is the intake manifold volume and R is the gas constant. Thus, the differential equation (1), taking into account the ideal gas equation (2), yields the following differential equation for the intake manifold pressure ps:

VS / (R * TS) * dps / dt = ms _to - ms _ab (3).

Depending on a desired output of the internal combustion engine 1, for example in the form of the resulting target torque, as in this example of the driver command torque FW or derived therefrom, a setpoint for the intake manifold pressure is formed and the temporal change of the intake manifold pressure dps / dt in the expert known manner formed as a difference quotient of the difference between the target value for the intake manifold pressure and a current intake manifold pressure value per unit time. As a time unit, for example, the predetermined time constant of the proportional time element used for the given time profile can be used. Thus, the differential equation (3) for the intake manifold pressure ps results from the dissolution after the mass flow ms flowing through the actuator 20 into the intake manifold 5, which corresponds to the desired mass flow _{to be set} by the actuator 20, the following calculation rule for this target mass flow:

ms _to = ms _from + VS / (R * TS) * 1 / T ₁ * (pssol - ps) (4) In this case, T _{1 is} the predetermined time constant of the proportional timer, pssol the desired intake manifold pressure and ps is the currently measured intake manifold pressure, ie the Istsaugrohrdruck.

The nominal intake pipe pressure pssol can be determined, for example, using the relationships known from DE 197 53 969 A1, as they are embodied there, for example, in FIG. 2 and the associated description. For the determination of the target intake pipe pressure pssol in the control unit 20, the relationships known from DE 197 53 969 A1 are therefore used by way of example. Accordingly, the effluent from the suction pipe 5 into the combustion chamber mass flow ms _ab can be determined in the skilled person known manner, as is known for example from DE 197 56 919 Al and there, for example in Figure 2 and the associated description. For the determination of the effluent from the suction pipe 5 into the combustion chamber mass flow ms ^ in the control unit 20, therefore, the known from DE 197 56 919 Al connections are used as an example.

First of all, the determination of the mass flow ms _ab flowing from the intake manifold 5 into the combustion chamber _{will be} described. For this purpose, the control unit 20 comprises a first map 95, to which the current engine speed n from the speed sensor 55 and the currently present camshaft adjustment NWS is supplied. The current camshaft adjustment NWS represents the ratio of the position of the intake camshaft to the position of the exhaust camshaft and indicates whether and to what extent, for example, a valve overlap exists between simultaneous opening of the intake valve 25 and the exhaust valve 30. The current camshaft adjustment NWS is known in the control unit 20 and stored, for example, in a fifth memory 92 of the control unit 20. Output of the first map 95 is a correction value PJagr, which is the system inherent exhaust gas recirculation due to the valve positions of the

Intake valve 25 and the exhaust valve 30 during the working cycle of the internal combustion engine 1 taken into account. Such system-inherent exhaust gas recirculation can arise, for example, due to valve overlap through phases of simultaneous opening of the intake valve 25 and the exhaust valve 30 and also depends on the current engine speed n. This correction value P_iagr is subtracted from the current intake manifold pressure ps, which is provided by the intake manifold pressure sensor 45, in a first subtraction member 120. The resulting effective intake manifold pressure at the output of the first subtraction element 120 is then multiplied by a factor F in a first multiplication element 130, which is composed of the pump equation and an empirically obtained function which determines the pulsation effects as a function of the current engine speed n and the current camshaft adjustment NWS composed. The pump equation takes into account the stroke volume VH of the cylinder 35, the current engine speed n, the gas constant R and the intake pipe temperature TS. The factor F is determined in a calculation unit 100 from the variables mentioned as follows:

F = (VH * n) / (2 * R * TS) * f (n, NWS) (5).

The stroke volume VH is also known in the control unit 20 and stored there in a second memory 80.

In equation (5), f (n, NWS) is the empirically obtained function that composes the pulsation effects in the intake manifold 5 as a function of the current engine speed n and the current camshaft adjustment NWS. As a result of the multiplication in the first multiplication element 130, the flowing out of the intake manifold 5 into the combustion chamber of the cylinder 35 or the mass flow results _from ms. This is supplied to a second addition member 155.

To determine the desired intake pipe pressure pssol is a second map

105 of the control unit 20, the driver's desired torque FW, which is assumed in this case, for example, as a resulting target torque, and the current engine speed n supplied. The second characteristic field 105 then forms the desired filling rlsol of the combustion chamber of the internal combustion engine 1 in a manner known to the person skilled in the art. Optionally, it may be provided that the driver desired torque FW or the resulting desired torque before delivery to the second characteristic field 105 is optionally optional of a load impact damping and / or one or more driveability filters is supplied. The desired filling rlsol is divided in a first division element 60 by a conversion factor fpsurl, which results at the output of a third multiplication element 140. The conversion factor fpsurl am Output of the third multiplier 140 is obtained by multiplying the output of a third map 110 with the output of a model 115. The third map 110 is the current camshaft angle ⁰ NW of the intake camshaft from the camshaft angle sensor 70 and secondly the current engine speed n supplied.

The camshaft angle sensor 70 detects the current camshaft position ⁰ NW of the intake camshaft in this example. Starting from the current position ⁰ NW of the intake camshaft, the current camshaft position ^O NW of the exhaust camshaft is also known and known with known camshaft adjustment NWS between the intake camshaft and the exhaust camshaft.

The third map 110 determines, depending on the camshaft position ⁰ NW of the intake camshaft and the current engine speed n in from

DE 197 53 969 Al known a factor KFPSU RL, which is supplied to the third multiplier 140. Model 115 also determines a combustion chamber temperature factor ftbr in a manner also known from DE 197 53 969 A1 as a function of the current engine temperature TM supplied by engine temperature sensor 60 and the current supplied by intake manifold temperature sensor 50

Suction tube temperature TS. The determined combustion chamber temperature is normalized to form the correction factor ftbr to a temperature of 273 K, to which the values of the third characteristic map 110 are tuned. The combustion chamber temperature correction factor ftbr is likewise supplied to the third multiplication element 140. Thus, the conversion factor fpsurl results at the output of the third

Multiplication element as follows:

fpsurl = ftbr * KFPSU RL (6)

In the first division member 160, the desired filling rlsol is then divided by the conversion factor fpsurl and the forming quotient at the output of the first division member 160 is fed to a first addition element 150 and added there to the output signal of a fourth characteristic field 180. On the one hand, the current engine speed n and, on the other hand, the current camshaft position ⁰ NW of the intake camshaft are fed to the fourth characteristic map 180. The output signal of the fourth map 180 is the map value KFPIRG which is supplied to the first adder 150. According to DE 197 53 969 A1, the fourth map 180 forms the residual gas fraction KFPIRG as a function of the current engine speed n and the current camshaft position ⁰ NW of the intake camshaft. As described in DE 197 53 969 A1, in FIG

For clarity, however, not shown, the read value KFPIRG the fourth map 180 are multiplied in a multiplication with a derived from a measured ambient pressure correction factor to perform a height correction.

In the first addition element 150, the possibly height-corrected value KFPI RG of the fourth characteristic map 180 is thus added to the quotient rlsol / fpsurl in order to form the nominal intake pipe pressure pssol at the output of the first addition element 150. This is fed to a second subtraction element 125, to which the current intake pipe pressure ps is also supplied. In the second subtraction element 125, the current intake pipe pressure ps is subtracted from the target intake pipe pressure pssol. The difference that forms is divided in a second division element 165 by the predetermined time constant T 1, which is stored in a third memory of the control unit 20. The predetermined time constant T 1 can be suitably applied, for example, to a test stand and / or in driving tests in order to realize a desired predetermined time profile of the actual filling. In this application, the predetermined time constant Tl can be a desired fuel consumption and / or a desired response of the internal combustion engine to a driver's request or a driver's desired torque back and / or a desired reproducibility for setting the desired

Output variable of the internal combustion engine 1, for example, the driver's desired torque by means of the target mass flow into the intake manifold 5 are determined such that, for example, the fuel consumption and / or the response and / or the desired reproducibility each assume an optimal value. Advantageously, for example, the response with higher priority than the desired reproducibility and the desired reproducibility with higher priority than the fuel consumption can be optimized. At the output of the second divider member 165, the quotient (pssol - ps) / Tl results, which is a fourth multiplier 145 is supplied and multiplied there with the intake manifold volume VS, which in the control unit 20 is known and stored in a fourth memory 90. The product formed by the fourth multiplication element 145 is supplied to a third division element 170 and divided there by the output of a second multiplication element 135. The output of the second multiplication element 135 is obtained by multiplying the current intake pipe temperature TS by the gas constant R, which is stored in a first memory 75 of the control unit 20. The quotient formed at the output of the third divisional element 170 is added in the second addition element 155 to the mass flow rnS _g b flowing out of the intake manifold 5 into the combustion chamber at the output of the first multiplication element 130. The forming sum at the output of the second adder 155 is then the

Target mass flow ms _{zuso |} which is set via the actuator 20 and to flow via the actuator 20 in the suction pipe 5. Thus, the target mass flow ms _{corresponds zuso |} at the output of the second summing element 155 calculated according to the equation (4) value for the incoming mass flow _ms.

When the actuator 20 now this setpoint mass flow ms _{ZUSO |} adjusts, also sets the desired filling dynamics according to the predetermined time course. This predetermined filling dynamics can, in turn, be used by other functions of the engine control, for example for the prediction of operating variables of the internal combustion engine 1. With the same dynamics of

Target mass flow ms _{zuso |} Also, the intake manifold pressure builds up in the intake manifold 5.

According to the described example, the actual filling builds up in a jump of the desired filling according to the predetermined time profile, for example, the proportional first-order timer.

By replacing the temporal change of the intake manifold pressure as a difference quotient of the difference between the Sollsaugrohrdruck pssol and the current intake manifold pressure ps per predetermined time constant Tl of the proportional timer, for example, first order behaves in the present case the

Control error, so the deviation between the Sollsaugrohrdruck pssol and the current intake manifold pressure ps in the form of the difference pssol - ps as the selected for the given time delay element in the form of the proportional first-order timer. This results in the desired dynamics according to the predetermined time course also for the difference between the actual filling and the desired filling.

Claims

claims

1. A method for operating an internal combustion engine (1) with a mass flow line (5) via which the internal combustion engine (1) is supplied to a mass flow, wherein a desired value is predetermined for a variable which is characteristic of the mass flow to the internal combustion engine (1), characterized in that the

Setpoint value of the variable characteristic of the mass flow, starting from a balance of the mass flow flowing into the mass flow line (5) and the mass flow flowing out of the mass flow line (5), is formed according to a predetermined time profile.

2. The method according to claim 1, characterized in that as a set value of the characteristic mass for the mass flow rate is selected for this mass flow and that as setpoint for the mass flow in the balance of in the mass flow line (5) inflowing mass flow and from the masses - Power line (5) effluent mass flow of in the mass flow line (5) flowing mass flow is selected.

3. The method according to any one of the preceding claims, characterized in that the predetermined time course is selected as a time course according to a proportional timer, preferably first order, with a predetermined time constant.

4. The method according to any one of the preceding claims, characterized in that a temporal change of the mass in the mass flow line (5) is formed as the difference between incoming mass flow and outflowing mass flow and that this relationship for determining the desired value of the mass flow characteristic size after the inflowing mass flow is resolved and the time change of the mass in the mass flow line (5) is replaced by the predetermined time course.

5. The method according to claim 4, characterized in that the relationship for determining the desired value of the characteristic for the mass flow size is resolved senstrom taking into account the ideal gas equation after the incoming mass flow, so that the temporal change of the mass in the mass flow line (5) in a temporal change of the pressure in the mass flow line (5) is converted, that depending on a desired output of the internal combustion engine (1) is a setpoint for the pressure is formed and that the change over time of the pressure as a difference quotient from the difference between the setpoint for the Pressure and a current pressure per unit time is formed.

6. The method of claim 5, as far as this is dependent on claim 3, characterized in that the predetermined time constant is selected as the time unit.

7. The method according to any one of the preceding claims, characterized in that the predetermined time profile with regard to a desired fuel consumption and / or a desired response and / or a desired reproducibility for setting a desired output of the

Internal combustion engine (1) is determined by means of the desired value of the variable characteristic of the mass flow.

8. Device (15) for operating an internal combustion engine (1) with a mass power line (5) through which the internal combustion engine (1) is supplied with a mass flow, with a control unit (20) which specify a desired value for a size is characteristic of the mass flow to the internal combustion engine (1), characterized in that the control unit (20) is designed such that it determines the desired value of the characteristic of the mass flow from a balance of the mass flow line (5) flowing mass flow and the forms the mass flow line (5) effluent mass flow according to a predetermined time course.