DE102008022213A1 - Method for determining pressure as model value according to throttle flap for volume limited by throttle valve, recirculating air flap and compressor, involves determining pressure according to throttle flap, and charge air pressure - Google Patents

Abstract

The method involves determining pressure according to a throttle flap (THR), and charge air pressure (CAP) depending on a respective calculating specification. An expression is integrated, where the expression has gas constant of air multiplied with a temperature in a volume multiplied with air mass flow balance of the volume and divided by an approximate value for a volume content of the volume. An independent claim is included for a device for determining pressure as a model value according to a throttle flap for a volume limited by throttle valve, recirculating air flap and compressor and charge air pressure as model value for a another volume, limited by compressor, recirculating air flap and cylinder of the internal combustion engine or charge air cooler.

Description

The The invention relates to a method and a device for determining from prevailing in an intake tract of an internal combustion engine To press.

For Control of an internal combustion engine becomes especially a knowledge an incoming in cylinder of the internal combustion engine Fresh air mass needed. A corresponding air mass flow is determined depending on sizes, which characterize a current operating state of the internal combustion engine. These quantities include, for example, a speed the internal combustion engine, a throttle position, an absolute Intake manifold pressure, a camshaft position and a temperature of Intake air.

The WO 96/32579 A1 discloses a method for model-based determination of the air mass flowing into the cylinders of an internal combustion engine. In a suction pipe of an intake tract of the internal combustion engine, a throttle valve is arranged. There are provided an opening degree of the throttle valve and a load signal of the internal combustion engine detecting sensors. Ratios in the intake tract are simulated by means of a Saugrohrfüllungsmodells, are used as the input variables, the opening degree of the throttle valve, an ambient pressure and a valve position representing parameters.

The DE 197 09 955 A1 discloses a method and apparatus for controlling an internal combustion engine. A charging device comprises a compressor which is bridged by a bypass line, in which a recirculation damper is arranged to control a recirculated air mass flow. An intake tract comprises a throttle valve which is arranged in an intake manifold of the internal combustion engine between the compressor and the cylinders of the internal combustion engine. An estimated value of a boost pressure is determined by a first observer, who includes a physical model of the supercharger, depending on a rotational speed of the engine and an opening degree of the recirculating-air damper. An estimate of air mass flow into the cylinders of the internal combustion engine is determined by a second observer, which includes a physical model of the intake tract, depending on engine speed, throttle opening degree, and estimated air pressure. An actuating signal for controlling an actuator is determined as a function of the estimated value of the air mass flow into the cylinders of the internal combustion engine.

The The object of the invention is to provide a method and a device create, the or a precise determination of in one Intake tract of an internal combustion engine prevailing pressures allows.

The Task is solved by the characteristics of the independent Claims. Advantageous developments of the invention are characterized in the subclaims.

The Invention is characterized by a method and a corresponding Contraption. A pressure after a throttle is considered a model size determined for a first volume, which is limited by the throttle, a recirculation damper and a compressor. Further is a boost pressure determined as a model size for a second volume, which is limited by the compressor, the Recirculation damper and either at least one cylinder of the internal combustion engine or a charging air cooler. The pressure after the throttle and the boost pressure are determined depending on a respective one Calculation rule that is derived depends on Equations that are in accordance with a respective physical Model for the first volume and for the second Volume has been set up separately for the first volume and for the second volume to a respective air mass flow balance.

Of the Term "before" is in the sense of upstream and the term "after" is used in the sense of downstream used. It is in this regard of a stationary Operation and with respect to the throttle and the compressor of a flow direction from an air inlet to cylinders the internal combustion engine and is in relation to the recirculation damper from a flow direction from downstream of Compressor out to the upstream of the compressor.

The Air mass flows that affect the first volume are in particular an air mass flow through the throttle valve, an air mass flow through the recirculation damper and an air mass flow through the compressor and optionally further air mass flows, such as for tank ventilation or crankcase ventilation. The Air mass flows that affect the second volume are in particular the air mass flow through the compressor, the air mass flow through the recirculation damper and an air mass flow in the cylinder of the internal combustion engine. The throttle and the recirculation damper are in particular independent controllable from each other, so that the air mass flow through the throttle and the air mass flow through the recirculation damper substantially independent from each other.

The advantage is that the pressure after the throttle and the boost pressure can be precisely determined for an intake tract of an internal combustion engine, wherein the throttle valve is arranged in front of the compressor. Furthermore, air mass flows in the intake tract depending on the determined pressure after the throttle and / or depending on the determined boost pressure precisely determined. The thus accurately determinable model sizes allow a precise pilot control of the internal combustion engine, especially in dynamic operation of the internal combustion engine. Furthermore, the model sizes can also be advantageously used for diagnostic purposes, for example for checking measured values of sensors which are arranged in the intake tract of the internal combustion engine, and / or can be used as substitute values in the event that a corresponding sensor should fail. As a result, a particularly reliable operation of the internal combustion engine is possible.

In an advantageous development is the calculation rule further derived by integrating a first term that includes a gas constant of air multiplied by a temperature in the first volume multiplied by the air mass flow balance of the first volume and divided by an approximation for a volume content of the first volume. The calculation rule is further derived by integrating a second expression, which includes the gas constant of air multiplied by a temperature in the second volume multiplied by the air mass flow balance of second volume and divided by an approximation for a volume content of the second volume. Further is derived the calculation rule by dissolving the both equations resulting from the respective integration after the pressure after the throttle and the boost pressure.

Of the first and second expressions each represent one Continuity equation for the respective volume and correspond to a first derivative of the respective pressure, the means the first derivative of the pressure after the throttle in the case of the first printout and the first discharge of the boost pressure in the case of the second term. From integrating the first expression and the second term results in two equations with the pressure after the throttle and the boost pressure as unknown. This Equation system is after the pressure to the throttle and after the charge pressure resolvable. The respective integration preferably takes place by applying the trapezoid rule. However, the integration can as well by applying a different integration algorithm. The pressure after the throttle and the boost pressure as well as dependent of these, the air mass flows are in the intake tract so precisely determinable.

embodiments The invention are explained below with reference to the schematic drawings. Show it:

1 an internal combustion engine with an intake tract,

2 a section of the intake tract with respect to a first volume,

3 a section of the intake tract with respect to a second volume,

4 a flowchart of a program for determining prevailing in the intake pressure according to a respective calculation rule and

5 a flow chart for deriving the respective calculation rule according to a respective physical model with respect to the first and the second volume.

elements the same construction or function are cross-figurative provided with the same reference numerals.

An intake tract of an internal combustion engine comprises an air filter AIC, a throttle valve THR and a compressor, which is preferably designed as a compressor COMP and which is bridged by a bridging line L, in which a recirculation flap RFP is arranged ( 1 ). The compressor COMP is designed, for example, as a mechanically driven supercharger which is coupled, for example, to a crankshaft of the internal combustion engine and which can be driven by this crankshaft. For example, the compressor COMP is coupled to the crankshaft via a transmission. As a result, a rotational speed of the compressor COMP is dependent on a rotational speed of the internal combustion engine. As a result, a compressor volumetric flow VOL_SCHA delivered by the compressor COMP is likewise dependent on the rotational speed of the internal combustion engine. With such an arrangement of the compressor COMP, therefore, it does not constitute an actuator, that is to say an actuator of the internal combustion engine and in particular of the intake tract with respect to an air mass control.

Furthermore, a charge air cooler ICO or more than one charge air cooler ICO may be provided in the intake system. The internal combustion engine comprises, for example, a first bank B1 and a second bank B2 of cylinders. Each bank may each be assigned a separate intercooler ICO. However, it can also be the first and the second bank 31 . 32 be associated with a common intercooler ICO. In the following it is assumed that at least one intercooler ICO is provided. However, it can also be dispensed with the provision of the at least one charge air cooler ICO.

Throttle valve THR is on the input side of the compressor COMP, that is, located upstream of the compressor COMP. The bypass line L flows between the throttle valve THR and the compressor COMP into a connection line connecting the throttle valve THR and an input of the compressor COMP. The air filter AIC is disposed upstream of the throttle valve THR. On the output side, the compressor COMP is connected to an input of the intercooler ICO. The intercooler ICO are the output side connected to the first bank B1 and the second bank B2, so with the cylinders of the internal combustion engine.

Limited through the throttle valve THR, the recirculation damper RFP and the compressor COMP is a first volume VOL1 formed. In other words is the first volume VOL1 formed downstream of the throttle THR, downstream of the recirculation damper RFP and upstream of the compressor COMP. With respect to the respective flow direction is from a stationary operating state of the internal combustion engine went out. The flow direction then runs from an air intake through the throttle THR and the compressor COMP and by the optionally provided intercooler ICO towards the cylinders of the internal combustion engine. Regarding the Recirculation damper RFP runs the flow direction from an output of the compressor COMP to its input. Of the The term "before" is used below in the sense of "upstream" and the term "after" in the sense of "downstream" used.

A second volume VOL2 is defined bounded by the compressor COMP, the recirculation damper RFP and the first and second banks B1, B2. In other words, the second volume VOL2 is formed downstream of the compressor COMP, upstream of the recirculation damper RFP, and upstream of the first and second banks B1, B2. In 2 is a section of the intake tract with respect to the first volume shown VOL1 and in 3 FIG. 2 shows a section of the intake tract with respect to the second volume VOL2. It can be provided to introduce an air mass flow FLOW_CPS of a tank ventilation and / or an air mass flow FLOW_CRCV of a crank gas ventilation and / or other air mass flows into the first volume VOL1.

4 shows a flowchart of a program for determining prevailing in the intake manifold of the internal combustion engine pressures and in particular for determining a pressure PDT after the throttle THR and a boost pressure CAP. The program is preferably executed by a control unit ST. The control unit ST can also be referred to as a device for determining pressures prevailing in the intake tract of the internal combustion engine. Preferably, the control unit ST is designed to control the internal combustion engine. The control unit ST is preferably coupled on the input side with sensors of the internal combustion engine and in particular with sensors of the intake tract and is preferably coupled on the output side with actuators of the internal combustion engine. Specifically, the throttle valve THR and the recirculation damper RFP are independently controlled by the control unit ST during operation of the internal combustion engine.

The Program starts in a step S1. In a step S2 for determining the pressure PDT after the throttle THR and the boost pressure CAP required measured values of measured variables detected by sensors and / or required model values of Model sizes determined. These measurements and / or model sizes include in particular temperatures, For example, a temperature T1 in the first volume VOL1, the essentially an air temperature T_SCHA_UP in front of the compressor COMP corresponds to a temperature T2 in the second volume VOL2, the essentially one air temperature T_SCHA_DOWN after the compressor COMP corresponds to a temperature T_THR at the throttle THR and / or a temperature T_RFP at the recirculation damper RFP. Further include these measurements and / or model sizes also one depending on a current throttle position detectable effective throttle section AR_RED_THR and / or a determinable depending on a current Umluftklappenposition effective recirculating air flap cross section AR_RED_RFP.

In a step S3, for a current time step n, the pressure PDT after the throttle valve THR is determined as a model size as a function of a predetermined calculation rule for determining the pressure PDT after the throttle valve THR. Input variables of the calculation specification are, in particular, the effective throttle valve cross section AR_RED_THR, the effective circulating air flap cross section AR_RED_RFP, the temperature T1 in the first volume VOL1, and the temperature T2 in the second volume VOL2. Further input variables of the calculation rule are in particular a volume content V1 of the first volume VOL1 and a volume content V2 of the second volume VOL2. The volume content V1 of the first volume VOL1 and the volume content V2 of the second volume VOL2 are in particular approximate values. In the event that one or more than one charge air cooler ICO is provided, the volume content V2 of the second volume VOL2 also includes a volume content of the respective charge air cooler ICO. Furthermore, model values of the pressure PDT determined after the throttle flap THR and the boost pressure CAP and also for at least one preceding time are also determined for at least one preceding time step n-1 Step n-1 determined first time derivative PDT_DRV1 the pressure PDT after the throttle valve THR and first time derivative CAP_DRV1 of the boost pressure CAP other input variables of the calculation rule.

In In a step S4, the determined model value of the pressure PDT is after the throttle valve THR provided, for example, for controlling the internal combustion engine depending on the detected pressure PDT after the throttle THR. For example, depending on the determined model value of Pressure PDT after the throttle valve THR a pilot control of the internal combustion engine in a dynamic operation of the internal combustion engine particularly precise and done reliably. The determined model value of the However, pressure PDT after the throttle THR can also be used for example, to check a reading, the by means of an optionally provided pressure sensor in the first volume VOL1 was detected, or to replace such Measured value, if it was detected as faulty, for example due to a defect of the pressure sensor. Furthermore, it can be provided be in a step S5 at least one air mass flow in the Intake tract of the internal combustion engine depending on the determined Model value of the pressure PDT after the throttle THR to determine. In particular, an air mass flow MAF_SCHA through the compressor COMP can be determined precisely.

Corresponding the step S3 is in a step S6 for the current Time step n the boost pressure CAP as model size depending on a given calculation rule for determines the determination of the boost pressure CAP. The input variables of this Calculation instructions largely correspond to those of the calculation rule for determining the pressure PDT after the throttle THR. According to the step S4, in a step S7, the determined Model value of the boost pressure CAP provided. The uses this model value of the boost CAP and the resulting benefits essentially correspond to those of the determined model value of the Pressure PDT after the throttle THR. In a step S8 can be further provided, an intake manifold pressure MAP dependent determined by the determined model value of the boost pressure CAP and / or at least one air mass flow in the intake tract of the internal combustion engine depending on the determined model value of the boost pressure CAP to determine. In particular, an air mass flow MAF_CYL in cylinder of the internal combustion engine depending on the intake manifold pressure MAP and thus dependent on the determined model value the boost pressure CAP and a mass air flow MAF_RFP through the recirculation damper RFP can be determined precisely.

The Program will be in after a predetermined interval TW in the step S2 continued. This replaces the previously current time step n the previous time step n-1. The pressure PDT after the throttle THR and the boost pressure CAP and possibly also the air mass flows become for the next and now current time step n determined.

5 shows a flowchart for deriving the respective calculation rule for determining the pressure after the throttle valve PDT THR and for determining the boost pressure CAP according to a respective physical model. The one on the left side of 5 The derivation steps illustrated relate to a physical model with respect to the first volume VOL1. The one on the right side of 5 illustrated derivation steps relate to a physical model with respect to the second volume VOL2. For the first volume VOL1 and for the second volume VOL2, that is to say for the physical model of the first volume VOL1 or for the physical model of the second volume VOL2, equations for a respective air mass flow balance according to the respective physical model are set up separately.

In a step S01, according to the physical model for the first volume VOL1, equations are set up for the air mass flows relating to the first volume VOL1. These air mass flows include a mass air flow MAF_THR through the throttle THR, the mass air flow MAF_RFP through the recirculation damper RFP and the mass air flow MAF_SCHA through the compressor COMP. Furthermore, where appropriate, in 2 However, the air mass flow FLOW_CPS of the tank ventilation and / or the air mass flow FLOW_CRCV of the crank gas ventilation and / or other air mass flows must be taken into consideration, which however can be regarded as known input variables with respect to the physical model for the first volume VOL1, which are recorded as measured values by means of sensors or as model variables according to others physical models are determined. In step S01, the mass air flow MAF_THR is expressed by the throttle THR as a product of the effective throttle area AR_RED_THR, an air mass flow coefficient MAF_MDL_CON_1 depending on the air temperature T_THR at the throttle THR, a pressure PUT before the throttle THR, and a flow coefficient PSI depending on a throttle pressure PQ_THR.

Between an ambient pressure AMP upstream of the air filter AIC and the pressure PUT upstream of the throttle valve THR, there is essentially an air mass flow-dependent pressure drop. This pressure drop is preferably stored as a characteristic in Dependence on the air mass flow through the air filter AIC, which essentially corresponds to the air mass flow MAF_THR through the throttle valve THR. Therefore, the pressure PUT before the throttle valve THR can be expressed as a difference of the atmospheric pressure AMP and a pressure drop at the air cleaner AIC.

Of the Ambient pressure AMP is the reading of an ambient pressure sensor detectable or as a model size dependent can be determined from other model sizes and / or measured values and represents with respect to the physical model for the first volume VOL1 is a known quantity that is the pressure PUT before the throttle THR depends on the ambient pressure AMP can be determined, so that the pressure PUT before the Throttle valve THR with respect to the physical model for the first volume VOL1 represents a known quantity. The pressure PUT in front of the throttle valve THR can alternatively also be used as a measured value be detected when a corresponding pressure sensor in front of the throttle THR is provided. It may alternatively be provided that the Air mass flow MAF_THR through the throttle valve THR in a map is stored.

In In step S01, the mass air flow MAF_RFP is further controlled by the Recirculation flap RFP expressed as a product of the effective Recirculation damper cross section AR_RED_RFP, the air mass flow coefficient MAF_MDL_CON_1 depends on the air temperature T_RFP the recirculation damper RFP, the boost pressure CAP and the flow coefficient PSI dependent on a recirculating air flap pressure ratio PQ_RFP. It may alternatively be provided that the air mass flow MAF_RFP is stored by the throttle flap RFP in a map. The mass air flow MAF_SCHA through the compressor COMP is expressed by the pressure PDT after the throttle THR multiplied by the compressor volumetric flow VOL_SCHA depending on a Compressor pressure ratio PQ_SCHA and divided by a Product of a gas constant R of air with the air temperature T_SCHA_UP in front of the compressor COMP. The compressor volumetric flow VOL_SCHA is stored for example in a map. It may, however, alternatively be provided that the air mass flow MAF_SCHA through the Compressor COMP is stored for example in a map.

Out the air mass flows referred to in step S01, the is called in particular from the air mass flow MAF_THR the throttle valve THR, the mass air flow MAR_RFP through the recirculation damper RFP, the mass air flow MAF_SCHA through the compressor COMP and optionally further air mass flows, for example the air mass flow FLOW_CPS of the tank ventilation and / or the air mass flow FLOW_CRCV of the crankcase ventilation, an air mass flow balance for the first volume VOL1 is formed. In a step S02, the first time derivative PDT_DRV1 of the pressure PDT after the throttle THR expressed as Product of this air mass flow balance, the gas constant R of air and the temperature T1 in the first volume VOL1 divided by the volume content V1 of the first volume VOL1.

In In a step S03, the first time obtained in the step S02 becomes Derivative PDT_DRV1 the pressure PDT after the throttle THR integrated. For integration, the trapezoid rule is used as an example. However, it is also possible to have a different integration rule apply. By integrating by means of the trapezoidal rule is the Pressure PDT after the throttle THR for the current time step n expressed as the sum of the pressure PDT after the throttle THR at the previous time step n-1 and a product of a half segment time T_SEG and a sum of the first temporal Derivative PDT_DRV1 of the pressure PDT after the throttle valve THR too the current time step n and the first time derivative PDT_DRV1 of the pressure PDT after the throttle valve THR to the previous one Time step n-1.

In Step S04 becomes the equation obtained in step S03 for the pressure PDT after the throttle THR to the current Time step n is the equation obtained in step S02 for the current and for the previous time step n, n-1 of the first derivative PDT_DRV1 of the pressure PDT after the throttle THR are inserted and placed in these in step S01 Equations for the mass air flow MAF_THR through the throttle THR, the air mass flow MAF_RFP through the recirculation damper RFP and the mass air flow MAF_SCHA used by the compressor COMP. The result is a first equation with the two unknown pressures PDT after the throttle THR and boost CAP. The flow coefficient PSI is preferably for the sake of simplicity as a piecewise linear Approximated stored, for example in the form of a characteristic. A slope value PSIS and a displacement value PSIO of the flow coefficient PSI represent a displacement, also referred to as "offset" can be, as well as a slope of the respective straight section of the approximated flow coefficient. The flow coefficient However, PSI can also be expressed differently.

According to steps S01 to S04, in steps S05 to S08, a second equation having the two unknown pressures PDT after the throttle valve THR and boost pressure CAP according to the physical model of the second volume VOL2 derived. In a step S05, according to the physical model for the second volume VOL2, equations are set up for the air mass flows relating to the second volume VOL2. These air mass flows comprise the air mass flow MAF_RFP through the recirculating air flap RFP, the air mass flow MAF_SCHA through the compressor COMP and an air mass flow MAF_IM through the respective intake manifold or the air mass flow MAF_CYL in the cylinder of the internal combustion engine. With regard to the air mass flow MAF_RFP through the recirculation damper RFP and the mass air flow MAF_SCHA through the compressor COMP, reference is made to the comments on the step S01.

at a small volume in the intercooler ICO or in the intercoolers ICO and after this or This can be assumed simplifying that the air in a room between intercooler ICO and intake valves of the cylinders the internal combustion engine has no own dynamics, that is an air mass flow through the intercooler ICO or the Intercooler ICO substantially equal to the mass air flow MAF_CYL in cylinder of the internal combustion engine is. Further, it becomes simplistic an isobaric cooling in the intercooler or assumed in the intercoolers. Then there is between the boost pressure CAP before the intercooler ICO or before the Intercoolers ICO and the intake manifold pressure MAP after this or according to these only an air mass flow dependent Pressure drop. This pressure drop is preferably as a characteristic stored in dependence on the air mass flow through the intercooler ICO or through the intercooler ICO, that is essentially dependent on the air mass flow MAF_CYL in cylinder of the internal combustion engine. The respective intake manifold pressure MAP can therefore be considered the difference of the boost pressure CAP and a pressure drop PRS_LOSS_ICO expressed on the respective intercooler ICO become. The respective air mass flow MAF_CYL in cylinders of the internal combustion engine can then be expressed in a simplified way by the respective Intake manifold pressure MAP multiplied by a respective slope value ETAS a sip line of the internal combustion engine minus a respective Displacement value ETAO of the intake line of the internal combustion engine. The Schlucklinie the internal combustion engine is preferably as piecewise linearly approximated stored, for example in the form of a characteristic. The slope value ETAS and the displacement value ETAO of the sipline represent a shift, which can also be referred to as "offset", and a slope of the respective straight section of the approximier th Absorption line. The air mass flow MAF_CYL in cylinder of the internal combustion engine but it can also be expressed differently. Especially can use more terms and in particular nonlinear terms be provided to the mass air flow MAF_CYL in cylinders of the Express the internal combustion engine more precisely. For example a further shift value can be taken into account, which depends on an exhaust backpressure and depending can be determined from a valve position. This can be a nonlinear Relationship between the intake manifold pressure MAP and the mass air flow MAF_CYL in cylinders of the internal combustion engine with large valve overlaps be taken into account. This is generally only relevant to internal combustion engines, which has a very wide adjustment range intake and exhaust camshafts.

Out the air mass flows mentioned in step S05, the is in particular from the air mass flow MAF_RFP by the recirculation damper RFP, the mass air flow MAF_SCHA through the compressor COMP and the air mass flow MAF_IM through the respective intake manifold or according to the air mass flow MAF_CYL in cylinders of the internal combustion engine becomes an air mass flow balance for the second volume VOL2 formed. In a step S06, the first time derivative CAP_DRV1 the boost pressure CAP expressed as the product of this air mass flow the gas constant R of air and the temperature T2 in the second Volume VOL2 divided by the volume volume V2 of the second volume VOL2.

In In a step S07, the first time obtained in the step S06 becomes Derivation CAP_DRV1 of the boost pressure CAP integrated. For the In accordance with step S03, the trapezoidal rule is integrated as an example applied. However, it is also possible to have a different integration rule apply. By integrating by means of the trapezoidal rule is the boost pressure CAP expressed for the current time step n as the sum of the boost pressure CAP at the previous time step n-1 and a product of the half segment time T_SEG and one Sum of the first time derivative CAP_DRV1 of the boost pressure CAP to the current time step n and the first time derivative CAP_DRV1 of the boost pressure CAP to the previous time step n-1.

In a step S08, the equation for the boost pressure CAP obtained in the step S07 at the current time step n becomes the equation obtained in the step S06 for the current and for the preceding time step n, n-1 of the first time derivative CAP_DRV1 of the boost pressure CAP are used and are in this the established in step S05 equations for the mass air flow MAF_RFP through the recirculation damper RFP, the mass air flow MAF_SCHA through the compressor COMP and the air mass flow MAF_IM through the respective intake manifold or the respective air mass flow MAF_CYL in cylinder Internal combustion engine used. The result is the second equation with the two unknown pressure PDT after the throttle THR and boost CAP.

The equation system formed by the first and second equations with the two unknowns is resolved in a step S09 after the pressure PDT after the throttle THR and is in one Step S010 dissolved after the boost pressure CAP. The in the Representing steps S09 and S010 the respective calculation rule, which in steps S3 and S6 are used to determine the pressure PDT after the throttle THR or the boost pressure CAP.

Prefers it is provided that the model value determined in step S3 the pressure PDT after the throttle THR and the determined model value each of the boost pressure CAP be fed to a controller for matching with an optionally by means of a respective Sensors actually detected in the first or second volume VOL1, VOL2 prevailing pressure.

All Input variables of the described method, in particular Temperatures and pressures can be used as model sizes determined or recorded as measured variables. For example, the ambient pressure AMP, the pressure PDT after the throttle THR, the air temperature T_SCHA_UP in front of the compressor COMP and the intake manifold pressure MAP as measured variables detected by means of correspondingly provided pressure or temperature sensors. Other sizes, such as the air temperature T_SCHA_DOWN after the compressor COMP, the air temperature T_THR the throttle valve THR and the air temperature T_RFP at the recirculation damper, are determined as model sizes. The assignment, which of the variables as measured variables recorded or determined as model sizes, but it can also be different. In particular, it is through the benefit of described calculation rules possible, the pressure PDT after the throttle valve THR and the boost pressure CAP and possibly dependent of these the intake manifold pressure MAP and / or air mass flows, in particular the air mass flow MAF_CYL in cylinders of the internal combustion engine, exclusively or almost exclusively dependent of model sizes, ie without or almost without recourse to measured values. For example, only the ambient pressure sensor for detecting the ambient pressure AMP or the pressure sensor for detecting the pressure PUT before the throttle THR provided.

AIC

air filter

AMP

ambient pressure

AR_RED_RFP

effective Recirculated air flap section

AR_RED_THR

effective Throttle area

31

first Bank

32

second Bank

CAP

boost pressure

CAP_DRV1

first Timing of the boost pressure

COMP

compressor

Etao

shift value the swallow line

ETAS

slope value the swallow line

FLOW_CPS

Air mass flow the tank ventilation

FLOW_CRCV

Air mass flow the crankcase ventilation

ICO

Intercooler

L

bypass line

MAF_CYL

Air mass flow in cylinders

MAF_IM

Air mass flow through the suction pipe

MAF_MDL_CON_1

Air mass flow coefficient

MAF_RFP

Air mass flow through the recirculation damper

MAF_SCHA

Air mass flow through the compressor

MAF_THR

Air mass flow through the throttle

MAP

Intake manifold pressure

n

current time step

n-1

previous time step

PDT

print after the throttle

PDT_DRV1

first time derivative of the pressure after the throttle

PQ_RFP

Recirculated air dampers pressure ratio

PQ_SCHA

Compressor pressure ratio

PQ_THR

Throttle pressure ratio

PRS_LOSS_ICO

pressure drop on the intercooler

PSI

Flow Coefficient

PSIO

shift value the flow coefficient

PSIS

slope value the flow coefficient

PUT

print in front of the throttle

R

gas constant of air

RFP

recirculation damper

ST

control unit

T_RFP

air temperature at the recirculation damper

T_SCHA_DOWN

air temperature after the compressor

T_SCHA_UP

air temperature in front of the compressor

T_SEG

Segment period

T_THR

air temperature at the throttle

T1

temperature in the first volume

T2

temperature in the second volume

THR

throttle

TW

specified interval duration

V1

volume content of the first volume

V2

volume content of the second volume

VOL_SCHA

Compressor flow

VOL1

first volume

VOL2

second volume

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• WO 96/32579 A1 [0003]
• - DE 19709955 A1 [0004]

Claims (3)

Method in which - a pressure (PDT) after a throttle (THR) as a model size is determined for a first volume (VOL1) that is limited is through the throttle valve (THR), a recirculation damper (RFP) and a compressor (COMP), and - a boost pressure (CAP) as model size is determined for a second volume (VOL2) that is limited is through the compressor (COMP), the recirculation damper (RFP) and either at least one cylinder of the internal combustion engine or a charge air cooler (ICO), where the pressure (PDT) after the throttle (THR) and the boost pressure (CAP) can be determined depending on one respective calculation rule, which is derived dependent of equations that according to a respective physical Model for the first volume (VOL1) and for the second volumes (VOL2) have been set up separately for the first volume (VOL1) and for the second volume (VOL2) too a respective air mass flow balance. The method of claim 1, wherein the calculation rule furthermore derived - by integrating a first Term, which includes a gas constant (R) multiplied by air multiplied by a temperature (T1) in the first volume (VOL1) with the air mass flow balance of the first volume (VOL1) and divided by an approximate value for a volume content the first volume (VOL1), - by integrating a second term, which includes the gas constant (R) multiplied by air multiplied by a temperature (T2) in the second volume (VOL2) with the air mass flow balance of the second volume (VOL2) and divided by an approximate value for a volume content of the second Volume (VOL2), and - by dissolving the both equations resulting from the respective integration after the pressure (PDT) after the throttle (THR) and the boost pressure (CAP). Device that is formed - to the Determining a pressure (PDT) after a throttle valve (THR) as a model size for a first volume (VOL1), which is limited by the throttle valve (THR), a recirculation damper (RFP) and a compressor (COMP), and - to determine a boost pressure (CAP) as model size for a second volume (VOL2) limited by the compressor (COMP), the recirculation damper (RFP) and either at least one cylinder the internal combustion engine or an intercooler (ICO), in which determining the pressure (PDT) after the throttle (THR) and the boost pressure (CAP) is dependent on a calculation rule, which is derived dependent on equations, which according to a respective physical model for the first volume (VOL1) and separately for the second volume (VOL2) have been made for the first volume (VOL1) and for the second volume (VOL2) to a respective air mass flow balance.