DE19740918A1 - Internal combustion engine gas flow control - Google Patents

Abstract

The gas flow (msdk) through the throttle valve is computed from the actual throttle setting value (wdkba) in order to control the gas flow through a throttle valve, to the combustion zone of an internal combustion engine. A difference (msdif) is registered between the computed gas flow through the throttle valve and the actual gas flow (mshfm). The registered difference is taken into account in computing the nominal throttle setting value (wdks). Also claimed is an assembly with a throttle valve control computer system (403,404) which computes the gas flows and registers the difference between computed and actual gas flows through the throttle valve.

Description

State of the art

The invention relates to a method and a device to control a gas flow via a throttle valve in an internal combustion engine. The invention relates in particular such a method and such Device for use in automotive engineering.

In the combustion chamber of an internal combustion engine Generation of an engine torque an air / fuel Ge mixed ignited. The one filled in the combustion chamber Gas mass should be controlled and recorded as precisely as possible, because u. a. the engine torque, the one to be injected Fuel quantity and the ignition timing determined.

In modern engine controls, using a so-called "electronic accelerator pedal" the pedal position interpreted as a request for a moment. This moment request is converted into a target value for the air mass flow. A function "filling control" calculates from the Torque request a target air mass flow and one from it Setpoint for throttle valve control. A rule element controls the throttle valve to the setpoint. A downstream hot film air mass sensor (HFM) measures the Actual air mass flow. Due to tolerances in HFM and in  Calculation path of the air mass flow calculation via the Throttle valve creates a difference between the actual and the setpoint of the air mass flow and between the actual Mo. ment and the desire for moments.

To eliminate these inaccuracies, is from the EP 0 375 710 B1 discloses an adjustment system which is not has only one setting unit, but via two adjustment units. In the known device there the first setting unit sends the control signal to the Adjustment distance, while the second adjustment unit is used to calibrate the first setting unit. In the known device is with a throttle valve based filling signal controlled the injection, wherein this relatively fast setting signal in steady state by means of an air mass meter is calibrated.

The invention is based on the problem of a method and a device for controlling a gas flow over a Provide throttle valve in an internal combustion engine, which adjust the gas flow quickly and precisely. About that the process should also be carried out inexpensively can and the device is inexpensive to manufacture and can be operated.

The problem is solved by those in the independent Claims disclosed methods and devices solved. Special embodiments of the invention are in disclosed in the subclaims.

The problem is solved in particular by a method for Control of gas flow via a throttle valve in a Combustion chamber of an internal combustion engine, with the steps: Calculate a throttle setpoint from a target gas flow, control of the throttle valve with the throttle  Target manipulated value, and determining an actual gas flow, characterized by the steps: calculate a Gas flow through the throttle valve based on a Actual throttle control value, determining a difference between the calculated gas flow through the throttle valve and Actual gas flow, and taking into account the determined difference when calculating the throttle setpoint, in particular by adjusting the target gas flow. It is from Advantage that the target air mass in the combustion chamber in converted into a throttle valve setpoint in one step which is an actual air mass with the accuracy of the sensor used to determine the actual gas flow sets. As a sensor for determining the actual gas flow comes in particular a hot film air mass sensor (HFM) Question. It is also advantageous that compared to the stand the technology an additional filling regulator, the subsequent adjustment of target and actual mass is eliminated. As a result, the manufacturing, maintenance and Operating costs reduced. It is also advantageous that through the one-step control of the throttle valve course is calmed, reducing the operating behavior of the whole Internal combustion engine unit is improved. Still is advantageous that the process is very fast and exact setting of the desired air mass flow enables. In particular, arises in the steady Condition no difference between the target filling and the actual filling measured by the hot film air mass sensor.

In a special embodiment of the invention that is Method characterized by determining at least two correction values when taking the difference into account between the gas flow through the throttle valve of the Throttle valve and the actual gas flow. This has the advantage that by determining at least two correction values, faster and more precise control behavior is achieved. It is also advantageous that by the determination  different from at least two correction values Fault sizes and disturbances are dealt with separately and can be compensated, which increases the accuracy and the speed of the control process is further improved.

In a further special embodiment of the invention the process is characterized by additives Taking into account at least one first correction variable and multiplicative consideration of at least one second correction quantity, the first and second Correction variables taken into account simultaneously or alternatively , especially the first correction variable, especially for the case of small gas flows is taken into account or is relevant, and the second correction factor especially for the case of large gas flows via the throttle valve is taken into account or is relevant. In another Design of this embodiment corrects the first Correction variable one by leakage air via the throttle valve caused errors, and the second correction quantity corrects one by incorrectly determining one Pressure before the throttle valve caused errors. This is advantageous because it makes the two mistakes their respective Error character can be treated accordingly, which increases the accuracy of the control process. It is particularly advantageous that a leakage air caused error that occurs in every operating state noticeable by an additive error, which however is particularly relevant for small gas flows, can be treated accordingly. Accordingly, a errors caused by faulty printer detection, which is noticeable in every operating state, and which is particularly relevant for large gas flows be treated accordingly. The two correction variables can preferably be taken into account at the same time, whereby a high control accuracy is achieved. All in all Such a design enables a very fast  and yet very precise and reliable control behavior, both the technical equipment and the computational control effort is low.

In a further special embodiment of the invention is at the end of the operation of the internal combustion engine at least one of the correction variables is stored. So that will advantageously achieved that immediately when the Operation of the internal combustion engine the full control accuracy is available. Storage of the correction values can be advantageous through appropriate electronic Components are made, for example by a SRAM device or by a magnetic Storage element.

In a further special embodiment of the invention is when the operation of the internal combustion engine starts a predetermined one for at least one of the correction variables Value used as a seed. This is beneficial because it makes it easy for certain Correction quantities determined a predetermined cold start value can be. The provision of predetermined values of advantage, because it also for the In the event of a long idle period of operation of the internal combustion engine or a loss of data or information regarding the previously determined correction values safe control behavior is guaranteed.

In a further special embodiment of the invention the target gas flow is based on at least one Torque requirement of the internal combustion engine determined. This is advantageous because of it for example in a motor vehicle with a Internal combustion engines don't just exceed the torque requirement the accelerator pedal can be considered, but also Torque requirements from an automatic  Gearbox of the motor vehicle or from an anti-slip regulation of the motor vehicle may be caused.

The problem underlying the invention also becomes solved by a device for controlling a Gas flow through a throttle valve in a combustion chamber Internal combustion engine with a throttle valve control an input signal for a target gas flow and a Output signal for a valve position, and one Transducer for determining an actual gas flow, characterized in that the throttle valve control Computing means that have a gas flow over the Throttle valve based on the throttle control value that continue to calculate a difference between that calculated gas flow via the throttle valve and the actual gas determine flow, this difference in the Calculation of the output signal is taken into account especially by adjusting the target gas flow. A such device according to the invention has the same Advantages already mentioned above for the were called method according to the invention. In particular is such a device advantageous because it is a fast and ensures precise control behavior, with the apparatus and computing requirements are low, so that such a device manufactured, maintained and operated at low cost can.

In a special embodiment of the invention at least two correction values when determining the Difference determined. It is advantageous that also complex error sizes and interferences quickly and with relatively little effort can be recorded, and a stable and precise control behavior is achieved. This applies in particular if the at least two correction variables Error sources with additive and multiplicative  Record fault characteristics separately and preferably take into account at the same time.

The teaching of the present invention also includes one Device which is one of the above-described executes control method according to the invention. Here combine the advantages of fast and accurate Tax procedure with the cost-effective implementation a device according to the invention.

The teaching of the present invention also includes Motor vehicle, which has a device as above described.

The present invention also encompasses Disk that is a control program to run one of the The invention described above Control process, or include parameters, to perform any of the above, The inventive method required or advantageous are. The data carrier can store the information in save in any form, especially in mechanical, magnetic, optical or electrical form. Advantageous are in particular electronic data carriers, for example a ROM, PROM, EPROM or EEPROM device that advantageously plugged into corresponding control units can be. With such data carriers Control parameters and control programs easily exchanged become, for example, a uniform Control unit for different vehicle types simply insert the appropriate data carrier can be configured.

Further advantages, features and details of the invention result from the subclaims and the following description, in which with reference to the  Drawings of several embodiments in detail are described. The can in the claims and in the features mentioned individually for each essential to the invention or in any combination be.

One way of carrying out the claimed invention is explained in detail below with reference to the drawings.

Fig. 1 shows a structure diagram for the charge detection with a hot-film air-mass sensor (HFM) and the determination of two correction values;

Fig. 2 is a structural diagram for the determination of the gas mass flow via the throttle valve;

Fig. 3 shows a structural diagram for the inventive fuel injection control and the calculation of the throttle valve angle.

Fig. 4 shows the inventive device for controlling a gas flow via a throttle valve.

The in the following description of the figures and in the Abbreviations and reference signs used in patent claims are at the end of the description with a short Explanation summarized.

Fig. 1 shows a structure diagram for the charge detection with a hot-film air-mass sensor (HFM) and for the determination of two correction amounts msndko and fkmsdk. In the upper signal path of FIG. 1, an air mass flow mshfm measured by the HFM is converted into a corrected relative charge r1 of a cylinder. For this purpose, the air mass flow mshfm measured by the HFM is first converted into an uncorrected relative charge rlroh a cylinder. This is done by dividing 111 the air mass flow mshfm measured by the HFM by a value that results from the multiplication 112 of an engine-specific constant KUMSRL and the engine speed nmot. The intake manifold pressure ps is determined from the uncorrected relative filling rlroh by using the gas equation and a corresponding integration 113 . By taking 114 further influencing variables into account in relation to the flow conditions in the intake manifold, the corrected relative charge r1 of the cylinder is calculated from the intake manifold pressure ps. From the intake manifold pressure ps together with the throttle valve angle wdkba of the throttle valve based on a stop and an intake air temperature correction factor ftvdk for converting the standard air mass flow to a mass flow at a current temperature, the air mass is calculated 115 via the throttle valve. The calculation of the air mass via the throttle valve msdk is shown in detail in FIG. 2. The difference msdif is formed by a subtraction 116 from the measured air mass flow mshfm and the calculated air mass flow msdk. By integrating 117 the difference value msdif, a first additive correction variable msndko is determined. In a corresponding manner, an integration 118 of the difference value msdif calculates a second multiplicative correction variable fkmsdk. The integrations 117 , 118 differ in particular by the integration constants or by the resulting physical unit. The additive correction variable msndko is directly fed back to the calculation of the throttle valve gas flow 115 . The multiplicative correction variable fkmsdk is also fed back to the calculation of the throttle valve gas flow via a multiplication 120 with an ambient pressure pvdkds measured by a pressure sensor while determining an effective pressure upstream of the throttle valve pvdk.

By taking the correction factors msndko and fkmsdk into account when calculating the gas flow via the throttle valve, the calculated value for the gas flow via the throttle valve msdk is approximated to the measured value mshfm. This improves the accuracy of this system in such a way that, if necessary, for example in the event of failure of the hot-film air mass sensor HFM, the calculation of the relative charge rl can be based exclusively on the calculated gas mass flow msdk. This is done by switching switch 119 in accordance with a corresponding switch signal B_ehfm.

In the multiplicative correction, for example assumes that the coming from the ambient pressure sensor Pressure value pvdk is tolerant, making a difference between the calculated gas mass flow msdk and the measured gas flow mshfm arises. The correction reacts to this difference by adjusting the multiplicative correction quantity fkmsdk until msdk is equal to mshfm. The pvdk size is after one steady adjustment with actual pressure before the throttle valve identical when the others Influencing factors would not be tolerant. Normally all the tolerances that can be found in the HFM path and occur in the throttle valve path, so that the Size pvdk from the actual pressure upstream of the throttle valve deviates. Nevertheless, the adaptation serves its purpose Throttle valve-based air mass flow calculation to the Air mass flow calculation based on the hot film air mass sensor is supported to adjust.

The size pvdkds can be one of a naturally aspirated Ambient pressure sensor can be derived and at a charged engine from a boost pressure sensor in front of the Throttle valve are derived. With a naturally aspirated engine a hot film air mass sensor and a pressure sensor in the  The intake manifold can be adjusted by adjusting the pressure pvdkds the intake manifold pressure can be learned. If no pressure sensor pvdkds is set to 1 and fkmsdk is immediately set pvdk, and the suction motor is Ambient pressure information in fkmsdk included with the Inaccuracies in the tolerances in the throttle valve and HFM system.

FIG. 2 shows a structural diagram for determining the gas mass flow msdk via the throttle valve in accordance with the calculation unit 115 from FIG. 1. The setpoint angle wdkba of a throttle valve of the throttle valve is initially available as an input signal. The target angle wdkba is preferably based on the stop of the throttle valve. The mass flow msndk after the throttle valve is calculated using a transfer function MSNWDK 201 determined on an air test bench. The additive correction variable msndko is added 202 to the mass flow msndk, which preferably detects the leakage air via the throttle valve under standard conditions. The value resulting from this addition 202 is multiplied 203 by an intake air temperature correction factor ftvdk in order to convert the standard air mass flow to an air mass flow at the current temperature. At the same time, a correction factor fpvdk for adapting the air mass flow at standard pressure upstream of the throttle valve to current conditions is determined from a pressure value pvdk in front of the throttle valve of the throttle valve using division 204 by the nominal pressure value 1013 hPa. The value pvdk is multiplied from an ambient pressure pvdkds measured by a pressure sensor and the multiplicative correction factor fkmsdk, as shown in FIG. 1. In addition, by forming quotient 205 from the intake manifold pressure ps and the pressure in front of the throttle valve of the throttle valve pvdk and a subsequent transfer function 206 , which is also referred to as the outflow characteristic curve and which serves to adapt the standard flow rate of the throttle valve measured at supercritical flow velocity to subcritical flow velocities Correction factor KLAF (ps / pvdk) determined. The two determined correction factors fpvdk and KLAF (ps / pvdk) are each taken into account by multiplying 207 , 208 by the mass flow. In summary, the air mass flow msdk is calculated as follows:

msdk = msndk × ftvdk × fpvdk × KLAF (ps / pvdk).

Fig. 3 shows the fuel injection control according to the invention by means of calculation of the target angle of the throttle valve of the throttle valve wdks from the target value for the air mass flow mssol. The setpoint for the air mass flow mssol is first changed in accordance with various correction variables. The filling control according to the invention is largely constructed inversely to the filling detection shown in FIG. 1. In particular, the correction variables msndko and fkmsdk determined in the course of the filling detection are used in the filling control according to the invention. First, analogously to FIG. 1, the parameters engine speed nmot and KUMSRL are multiplied 112 . The target value mssol is divided by the resulting product, which results in a target filling rlsol in the combustion chamber. After a further division 302 by a conversion factor fupsrl "intake manifold pressure in relative filling" and a subsequent addition 303 with a correction factor pirg, which takes into account the partial pressure of the internal exhaust gas recirculation, the target pressure pssol in the intake manifold is obtained. This value pssol is changed by means of a division 304 by a pressure pvdk in front of the throttle valve of the throttle valve and transferred to a transfer function 305 , which is also referred to as an "outflow characteristic" and which serves to adapt the standard flow rate of the throttle valve measured at supercritical flow velocity to subcritical flow velocities. The value pvdk is calculated by multiplication 306 from the ambient pressure pvdkds measured by a pressure sensor and the multiplicative correction factor fkmsdk, analogously to the calculation from FIG. 1. The value determined from the outflow characteristic curve 305 is then also multiplied 307 by an intake air temperature correction factor ftvdk to convert the standard air mass flow to an air mass flow at the current temperature and then by multiplying 308 by a correction factor fpvdk to adapt the air mass flow at standard pressure upstream of the throttle valve to the current conditions to the current temperature and pressure conditions. The correction factor fpvdk is determined by division 309 from the pressure pvdk in front of the throttle valve of the throttle valve by a nominal pressure of 1013 hPa. The value resulting from the calculations described above is subjected to a division 310 together with the target value mssol for the air mass flow. The additive correction value msndko, which takes into account the leakage air via the throttle valve under standard conditions, is then subtracted from the value resulting from the division 310 . The value msnwdks thus obtained is transferred to a transfer function WDKMSN 311 , which represents the inverted characteristic of the transfer function MSNWDK from FIG. 2 and thus results in a setpoint angle wdks of the throttle valve of the throttle valve from the corrected and adapted setpoint for the air mass flow msnwdks.

FIG. 4 shows the inventive device for controlling a gas flow via a throttle valve. The setpoint mssol for the air mass flow is determined from the position of an accelerator pedal 401 . The filling control 402 uses this, as shown in FIG. 3, to determine a desired angle wdks of a throttle valve 403 . The actual angle wdkba of the throttle valve is determined and serves as an input variable for the charge detection 404 . The filling detection 404 determines the mass flow msdk via the throttle valve from the value wdkba, as shown in FIG. 1. A hot film air mass sensor 405 connected downstream in the intake manifold 400 determines the air mass flow mshfm. As shown in FIG. 1, an additive correction value msndko and a multiplicative correction value fkmsdk are determined from the values msdk and mshfm in a comparator and integrator stage 406 . The two correction values are output both to the fill controller 402 and to the fill detector 404 and serve there as input variables. It is advantageous in this inventive device not only that the filling control 402 can set a throttle valve angle without a correction by a relatively slow controller, at which the setpoint and the value measured by the hot-film air mass sensor match, but also that before an injection with pre-storage the intake valve, at which the air mass flow must be known at the time when the intake valve closes, the throttle valve angle which is established at this later time is easier to estimate than a future air mass flow based on the hot-film air mass sensor signal. Based on this future throttle valve angle, the future air mass flow can be calculated and the current injection duration can thus advantageously be corrected, this prediction having the accuracy of the hot film air mass sensor on the basis of the correction factors.

Abbreviations

B_ehfm error signal, changeover signal
fkmsdk multiplicative correction quantity
fpvdk correction factor for adapting the air mass flow at standard pressure upstream of the throttle valve to current conditions = pvdk / 1013 hPa
ftvdk intake air temperature correction factor for converting the standard air mass flow to an air mass flow at the current temperature
fupsrl Conversion factor intake manifold pressure in relative filling
KLAF outflow characteristic curve for adapting the normal flow measured at supercritical flow velocity to subcritical flow velocities
KUMSPL parameters for determining the relative cylinder charge from the air mass flow and the speed of the engine, cylinder stroke volume
msdif difference between calculated and measured gas mass flow = mshfm - msdk
msdk calculated air mass flow via the throttle valve
mshfm mass air flow measured by the HFM
msndk mass flow after the throttle valve
msndko additive correction variable, leakage air via the throttle valve under standard conditions
msndks setpoint for air mass flow under standard conditions
MSNWDK (wdkba) standardized air mass flow via the throttle valve, measured on an air test bench
msnwdks adjusted target gas flow via the throttle valve
mssol setpoint for air mass flow under current conditions
nmoot engine speed
pirg Correction of the intake manifold pressure around the exhaust gas recirculation, partial pressure of the internal exhaust gas recirculation
ps pressure in the intake manifold
pssol Set pressure in the intake manifold
pvdk pressure in front of a throttle valve of the throttle valve = pvdkds × fkmsdk
pvdkds ambient pressure measured via pressure sensor
Air mass flowing into the intake manifold, uncorrected relative filling of a cylinder
rl air mass flowing out of the intake manifold, corrected relative filling of a cylinder
wdkba Actual angle of a throttle valve of the throttle valve, based on the stop
wdks target angle of a throttle valve of the throttle valve, based on the stop = WDKMSN (msnwdk)
WDKMSN inverse characteristic to MSNWDK

Claims (13)

1. A method for controlling a gas flow via a throttle valve into a combustion chamber of an internal combustion engine, comprising the steps:
Calculation of a throttle setpoint (wdks) from a set gas flow (mssol),
Actuation of the throttle valve with the throttle setpoint value (wdks), and
Determining an actual gas flow (mshfm), characterized by the steps:
Calculating a gas flow via the throttle valve (msdk) on the basis of an actual throttle control value (wdkba),
Determining a difference (msdif) between the calculated gas flow through the throttle valve (msdk) and the actual gas flow (mshfm), and
Taking into account the determined difference (msdif) when calculating the throttle setpoint (wdks). 2. The method according to claim 1, characterized by Determination of at least two correction variables (msndko, fkmsdk) when considering the difference (msdif) 3. The method according to claim 2, characterized by additive taking into account at least a first one Correction quantity (msndko), and multiplicative Taking into account at least a second one Correction size (fkmsdk). 4. The method according to claim 3, characterized in that  the first correction variable (msndko) one caused by leakage air corrected errors caused by the throttle valve, and that the second correction quantity (fkmsdk) by one an erroneous determination of a pressure before Throttle valve caused the error corrected. 5. The method according to any one of claims 2 to 4, characterized characterized in that upon termination of operations of the internal combustion engine at least one of the Correction quantities (msndko, fkmsdk) is saved. 6. The method according to any one of claims 2 to 5, characterized characterized in that at the start of operations of the internal combustion engine for at least one of the Correction quantities (msndko, fkmsdk) a predetermined one Value is used as a starting value. 7. The method according to any one of claims 1 to 6, characterized characterized in that the target gas flow (mssol) on the Basis of at least one requirement for the Torque of the internal combustion engine is determined. 8. Device for controlling a gas flow via a throttle valve ( 403 ) in a combustion chamber of an internal combustion engine
a throttle valve control ( 402 ) with an input signal for a desired gas flow (mssol) and an output signal for a valve position (wdks), and
a sensor ( 404 ) for determining an actual gas flow (mshfm),
characterized in that the throttle valve controller has computing means ( 403 , 404 ) which calculate ( 403 ) a gas flow via the throttle valve (msdk) on the basis of the throttle control value (wdks, wdkba) and which furthermore a difference (msdif) between determine ( 404 ) the calculated gas flow via the throttle valve (msdk) and the actual gas flow (mshfm), this difference (msdif) being taken into account when calculating the output signal (wdks). 9. The device according to claim 8, characterized in that the computing means ( 404 ) determine at least two correction variables (msndko, fkmsdk) when determining the difference (msdif). 10. The device according to claim 8 or 9, characterized characterized in that the device according to a method executes one of claims 1 to 7. 11. Motor vehicle, characterized by a device according to one of claims 8 to 10. 12. Data carrier, characterized in that the A control program to run a disk Method according to one of claims 1 to 7 includes. 13. Data carrier, characterized in that the Disk includes parameters to run of a method according to one of claims 1 to 7 are necessary or advantageous.