DE102007057445A1 - Internal-combustion engine operating method for motor vehicle, involves regulating parameter depending on signals in such manner that characteristic of audible noise is adapted to preset characteristic of desired noise of engine - Google Patents

Abstract

The method involves varying a control parameter for controlling an injecting valve (17) in dependence of confirmation signals (s1, s2), where the signals characterize an audible operating noise of an internal-combustion engine (19). A noise characteristic of a desired operating noise of the engine is preset and the control parameter is regulated depending on the signals in such a manner that noise characteristic of audible operating noise is adapted to the preset noise characteristic of the desired operating noise. An independent claim is also included for a fuel system for an internal-combustion engine, comprising a fuel injecting valve for injecting fuel into a combustion chamber of the engine.

Description

State of the art

The The invention relates to a method for operating an internal combustion engine, which at least one fuel injection valve for injecting having fuel in a combustion chamber of the internal combustion engine, wherein at least one control parameter for controlling the injection valve depending on at least one confirmed Signal that has an audible operating noise Internal combustion engine is characterized, is varied. The invention also relates to a fuel system for a Internal combustion engine.

From the EP 0 416 265 B1 For example, a method of controlling fuel injection is known. In this method, a minimum drive duration of a solenoid valve of a fuel pump is determined, in which just a pre-injection can be achieved. For the determination of the minimum drive duration, the solenoid valve is initially operated with a small drive duration, which is not yet sufficient for an opening. Subsequently, the drive time is successively increased. In the transition to a drive time, which is sufficiently long for an injection, the audible operating noise and thus also the feedback signal changes. In one embodiment, a feedback signal is simultaneously detected using a sensor for airborne noise generated by an internal combustion engine. The activation duration for the pilot injection, at which the feedback signal has changed, is stored as the adjustment value. This adjustment value corresponds to the minimum activation duration of the solenoid valve. It can be used in a control of the internal combustion engine. Since it must be intervened to determine the minimum driving time of the solenoid valve according to this method in the control of the internal combustion engine, the method can be performed only in the context of maintenance or in a specific operating condition of the internal combustion engine. With this method, age-related changes in the minimum drive duration of the solenoid valve can be detected. However, changes in an operating noise of the internal combustion engine which originate from other causes and which occur during its service life are not recognized.

Disclosure of the invention

task The invention is a method for operating a fuel system specify an internal combustion engine, in the deviations of an operating noise the internal combustion engine and / or a motor vehicle from a predetermined Operating noise eliminated or at least reduced.

to Solution of the task becomes a procedure with the characteristics of claim 1 and a fuel system with the features of Proposed claim 9.

The In particular, the invention allows a compensation of age-related changes an operating noise of the internal combustion engine by intervention to control parameters of the injection valve, so that only small, ideally no, changes in operating noise the internal combustion engine occur. Unlike known methods, need only provide a control of the drive parameters need none relative to the process of the invention complex maps are provided. Elaborate series of measurements in test stands for the determination of these maps can be omitted. In addition, you can in the realization of the method according to the invention also aging effects or manufacturing tolerances of the internal combustion engine or the motor vehicle are compensated, which by means of the known Control process only with great effort or not possible would. The method thus not only allows the most extensive Maintenance of operating noise over the lifetime the internal combustion engine or a motor vehicle, but allows also that different internal combustion engines or motor vehicles same series despite the manufacturing tolerances largely the same Operating noise.

in this connection it is particularly preferred that from the returned signal an Istparametersatz is determined, the at least one noise feature of the audible operating noise. On this way will be included in the returned signal Raw data to the relatively compact Istparametersatz compacted. Using the actual parameter set can then be checked with little computational effort whether, and to what extent the operating noise of the desired operating noise differs, and whether and to what extent the noise feature of desired operating noise in the actual existing operating noise is included.

It is further preferred that a desired parameter set is predetermined, which characterizes the at least one predefined noise feature of the desired operating noise, and in the case of a difference between the desired parameter set and the actual parameter set, the at least one actuation parameter is varied. The actual parameter set is thus compared with a corresponding desired parameter set, so that in a simple manner a deviation of the desired operating noise from the actual operating noise or a deviation of the corresponding noise characteristics can be determined from each other. For comparing the actual parameter set with the desired parameter set, suitable arithmetic operations can be applied to the individual parameters of the parameter sets. For example, a similarity measure can be calculated, which characterizes the difference between the desired parameter set and the actual parameter set. If there is a difference, the at least one drive parameter is varied until the difference is eliminated or decreased to an acceptable level.

Around a quick change between different desired Operating noise can be provided be that the setpoint set of a set of different predefined setpoint parameter sets is selected. In this case, the desired parameter set, for example, at the end of the assembly a motor vehicle in dependence on a model variant of the motor vehicle are selected. The selection can but also be left to the driver, so he, for example, between a sporty operating noise and a quieter Operating noise can switch.

• – das rückgemeldete Signal gefiltert wird,
• – mindestens ein Zeit-Frequenz-Muster mittels einer Wavelet-Analyse detektiert wird,
• – mindestens eine bestimmte Frequenz mittels einer Spektralanalyse detektiert wird und/oder
• – mindestens ein Muster im Zeitbereich des Signals detektiert wird.

In order to obtain an actual parameter set with parameters which precisely describe the noise feature, it is provided in a preferred embodiment of the invention that for determining the actual parameter set

• - the confirmed signal is filtered,
• At least one time-frequency pattern is detected by means of a wavelet analysis,
• - At least one specific frequency is detected by means of a spectral analysis and / or
• - At least one pattern in the time domain of the signal is detected.

ever after which noise characteristics of the operating noise in the execution of the invention Procedure to be considered, will be a selection or are all of the above-mentioned process steps used, wherein in various embodiments of the invention the order of these steps can also vary. For example becomes an operating noise that is higher in its spectrum having frequency components to a comparatively high degree, felt as a hard operating noise. A noise feature that a hard operating noise, for example, over a proportion of these relatively high frequencies on the confirmed Signal to be quantified. This is preferably done with a Spectral analysis, for example using a Fourier transform.

Prefers is also that the at least one control parameter to a control start and / or a drive time when driving the injector for at least one injection process, preferably a pre-injection process, equivalent. Thus, for example, by temporal Vorverlegen the Ansteuerbeginns while maintaining the Ansteuerdauer a temporal Distance between a pilot injection and a main injection increases become. As a result, at least in certain operating conditions the internal combustion engine for the hard operating noise characteristic high frequency components reduced. Is a soft one Operating noise given, the relatively low high-frequency Shares in its spectrum, then the time interval increased between the pilot injection and the main injection when, for example, by means of spectral analysis a high Percentage of high frequencies detected in the feedback signal has been. Conversely, if a harsh operating noise is given, in the absence of these high-frequency components in the spectrum of the feedback signal, the distance between the pre-injection and the main injection can be reduced.

to Detection of the returned signal is suitable in principle each sensor, with that of the internal combustion engine or the motor vehicle generated airborne sound can be detected. However, it is preferred that the confirmed signal with at least one microphone is detected. This microphone may be in an engine compartment, preferably be placed near the engine, and / or be mounted in a passenger compartment of the motor vehicle.

Around also to eliminate influences on the operating noise, which are not directly related to the operation of the internal combustion engine, can be provided that the at least one control parameter depending on another operating noise and / or ambient noise of a motor vehicle becomes. Such a further noise can happen for example, to act a wind noise. The further Noise and / or ambient noise, especially the Fahrtwindgeräusch, preferably at least predominantly detected by the second microphone.

When Another solution to the problem is a fuel system for an internal combustion engine with the features of claim 9 proposed. The inventive method leaves using such a programmed control or regulating device perform very easily. In addition, the set of nominal parameters, the at least one predetermined noise feature of characterized by the desired operating noise, changed by simply reprogramming the control or regulating device become. In a similar way, the predefined Setpoint parameter sets are changed.

In a particularly preferred embodiment, the fuel system first sound recording means for recording an audible Operating noise of the internal combustion engine. through This sound receiving means can be the returned signal be recorded.

It can be provided that the fuel system second sound receiving means for receiving at least one further operating noise and / or at least one ambient noise of a motor vehicle having. It can be provided that the second sound receiving means are located in a passenger compartment of the motor vehicle.

to simple and inexpensive capture of the confirmed Signal is preferred that at least one of the two sound receiving means at least a microphone and / or at least one signal conditioning arrangement for the preparation of a microphone signal recorded by the microphone. The signal conditioning arrangement can be an amplifier and / or an analog-to-digital converter.

Brief description of the drawings

Further Features and advantages of the invention will become apparent from the following Description in which exemplary embodiments will be explained in more detail with reference to the drawings. Showing:

1 a fuel system of an internal combustion engine in a schematic representation,

2 a flow chart of a method according to the invention;

3 a detailed representation of a step of the flowchart 2 ; and

4 a graphical representation of a pressure curve in a combustion chamber and a drive signal of an injection valve over time.

embodiments the invention

In 1 is a highly schematic representation of a fuel system 11 for an internal combustion engine 14 shown. The fuel system 11 is mostly in an engine room 13 accommodated. It has a control or regulating device 15 on that with injectors 17 the internal combustion engine 19 is to be controlled. Each injection valve 17 is adapted to fuel in exactly one combustion chamber (not shown) of the internal combustion engine 19 inject. In the embodiment shown, the internal combustion engine 19 four combustion chambers and thus four injection valves 17 on. However, the invention is also in connection with internal combustion engines 19 applicable, the a different number of combustion chambers or injection valves 17 exhibit. The injectors 17 are hydraulically connected to a common high-pressure fuel storage 21 (Common rail) connected. The high-pressure fuel storage 21 is connected to a high-pressure side of a high-pressure fuel pump (not shown).

In the engine compartment 13 are the first sound recording medium in the form of a first microphone 23 arranged. The first microphone 23 is with a first signal conditioning arrangement in the form of a first analog-to-digital converter 25 connected, which with calculating means 26 the control or regulating device 15 connected is. Furthermore, the fuel system points 11 through a second microphone 27 formed second sound receiving means via a second signal conditioning arrangement, which in the embodiment shown as a second analog-to-digital converter 29 is executed, with the calculation means 26 the control or regulating device 15 connected is. Unlike in the engine compartment 13 arranged first microphone 23 is the second microphone 27 in a passenger compartment 31 a motor vehicle arranged. In the embodiment shown, the two analog-to-digital converters 25 . 29 designed as separate modules. Every microphone 23 . 27 However, it can also be used with the associated analog-to-digital converter 25 . 29 be combined into an integrated module. Alternatively, the analog-to-digital converters 25 . 29 also in the control or regulating device 15 to get integrated. An embodiment not shown has only the first microphone 23 as well as the first analog-to-digital converter 25 on, while another embodiment, not shown, only the second microphone 27 and the second analog-to-digital converter 29 includes.

The control or regulating device 15 has a memory element 33 in, in which several - in the embodiment shown three - predefined target parameter sets 35 are stored. Furthermore, the control or regulating device 15 selection means 37 for selecting a desired parameter set Y from one of the predetermined desired parameter sets 35 on. The desired parameter set Y forms an input variable of a control element 39 the control or regulating device 15 ,

When operating the fuel system 11 is in the high-pressure fuel storage 21 stored fuel from the high-pressure fuel pump is placed under a high pressure, so that when an open injection valve 17 Fuel in the associated combustion chamber of the internal combustion engine 19 is injected. The control or regulating device 15 generated for each injector 17 individual control nale x, with which the injection valves 17 be controlled. Here, the drive signal x is selected such that at a suitable time results in a relatively long-lasting main injection, which is preceded by a time compared to the main injection pre-injection timing. In an embodiment not shown, multiple pilot injections are performed.

Depending on the timing of the pilot injection and the main injection, a certain operating noise of the internal combustion engine results 19 or of the motor vehicle. By means of the microphones 23 . 27 are generated microphone signals s ₁ , s ₂ , the analog-to-digital converters 25 . 29 be supplied. The analog-to-digital converter 25 . 29 convert the microphone signals s ₁ , s ₂ into corresponding digital signals s ₁ ', s ₂ ' corresponding to the computing means 26 the control or regulating device 15 be supplied. This will be from the first microphone 23 in particular those of the internal combustion engine 19 immediately generated operating noise, while the second microphone 27 In particular, operating noise is detected by persons in the passenger compartment 31 are perceptible. Especially the second microphone 27 recorded operating noise are in many cases not exclusively of the internal combustion engine 19 caused. For example, that of the second microphone 27 detected operating noise except one of the internal combustion engine 19 caused component also caused by a wind other component. The calculating means 26 determine in dependence on the digital signals s ₁ ', s ₂ ' an Istparametersatz V, which characterizes the noise feature.

The selection means 37 the control or regulating device 15 select from the predefined setpoint parameter sets 35 the desired parameter set Y and lead this to the control element 39 to. The rule element 39 In addition, the actual parameter set V, which depends on the microphone signals s ₁ and s ₂ , is supplied. In dependence on the digital signals s ₁ ', s ₂ ' and thus also in dependence on the microphone signals s ₁ , s ₂ , the control element controls 39 the control or regulating device 15 a control parameter, for example, such that the noise characteristic of the operating noise differs as little as possible from the given noise feature. As will be shown in more detail below, the drive parameter is in one embodiment, a control start for the pilot injection. The control or regulating device 15 , the internal combustion engine 19 with their injectors 17 as well as the microphones 23 . 27 and their associated analog-to-digital converters 25 . 29 So form a closed loop, the microphone signals s ₁ and s ₂ and the corresponding digital signals s ₁ ', s ₂ ' are returned signals that close the control loop.

The following is based on the 2 and 3 a method of operating the fuel system 11 in which the internal combustion engine 19 is regulated in dependence on the confirmed microphone signals s ₁ , s ₂ , explained in more detail. The method bears the reference numeral in its entirety 51 and is in 2 shown as a flow chart. After a start 53 of the procedure 51 gets in one step 55 the setpoint parameter set Y from the predefined setpoint parameter sets 35 by means of the selection means 37 selected and for the further course of the procedure 51 specified. After that, in one step 57 the microphone signals s ₁ , s ₂ detected. In a subsequent step 59 is determined from the microphone signals s ₁ , s ₂ of Istparametersatz V, which is a noise feature of the actual of the internal combustion engine 19 generated operating noise determined. Subsequently, in one step 61 checks whether there is a difference between the actual parameter set V and the set parameter set Y. For this purpose, a variable can be calculated which characterizes the difference between the actual parameter set V and the desired parameter set Y. If the actual parameter set does not differ from the setpoint parameter set (N), the step becomes 57 branched. It can also be provided that even then to step 57 is branched when the difference between the Istparametersatz V and the desired parameter set Y is less than a predetermined minimum value. Otherwise (Y) will be in one step 63 the control parameter for controlling the injection valve in response to the feedback signals, namely the two microphone signals s ₁ , s ₂ , varies. One recognizes by means of the 2 that the steps 57 . 59 . 61 and 63 form a loop that is executed during operation of the internal combustion engine, wherein the step 63 for varying the drive parameter is executed only if there is a deviation between the Istparametersatz V and the desired parameter set Y or - depending on the specific embodiment of the method 51 - the deviation is greater than the minimum value or the minimum value. In this way, a regulation for the internal combustion engine 19 provided that a constant adjustment of the drive parameter during operation of the internal combustion engine 19 both age-related or occlusive changes of the internal combustion engine 19 or of the motor vehicle as well as changing environmental conditions.

3 shows in detail how the Istparametersatz V from the returned microphone signals s ₁ , s _{2 is} determined in the embodiment shown. In one step 65 First, the two microphone signals s ₁ and s ₂ (or the corresponding digital signals s ₁ 'and s ₂ ') are filtered. Subsequently, in one step 67 a wavelet analysis for detecting time-frequency patterns is performed. This is followed by a step 69 in which a spear tral analysis is performed using a Fourier transform to detect certain frequency components. Finally, in the step 71 detected by suitable pattern recognition method pattern in the time domain of the confirmed microphone signals s ₁ , s ₂ . Deviating from this, in an embodiment, not shown, all or part of the in 3 shown steps 65 . 67 . 69 . 71 can be provided, the order of the proposed steps can be adapted to requirements that result from a specific application of the method.

By suitable embodiment of the embodiment shown, a variety of noise characteristics can be taken into account in the control, and it can be varied in principle any drive parameters in response to the feedback signal. The following is with reference to the 4 explains in more detail how a noise feature, referred to hereinafter as "roughness", can be included in the control, the start of control t ₁ for the pilot injection serving as the control parameter to be varied.

In an upper diagram of the 4 is a first time course 81 a pressure p in a combustion chamber of the internal combustion engine 19 shown. The first pressure gradient 81 indicates in the illustration of 4 before and after a time t _ZOT , to which a piston of the combustion chamber is in a top dead center in the power stroke (ignition TDC), each having a section with a relatively high slope. Also in a range between the time t _ZOT of top dead center and a maximum 84 is the slope of the first course 81 quite high. Furthermore, the first course 81 in a fast-falling section, the maximum 84 follows, a magnitude high slope. On the other hand, the slope of the first pressure curve 81 in the area of top dead center t _ZOT and at the maximum 84 relatively low.

In the middle diagram of the 4 the drive signal x is shown over the same time scale. At the time t ₁ , the drive signal x changes from an inactive state L to an active state H, whereby the injection valve 17 opening is controlled. The time t ₁ corresponds to a control start for a pilot injection. During the control period τ for the pilot, the signal remains active (H) and, on the expiry of the activation duration τ at the time t ₂ of an end of actuation for the pilot injection is deactivated (L). In a time interval At = t ₃ - t ₂ after the control end t _2, the drive signal is x starting with a time t ₃ to a time t ₄ again activated (H) to the injection valve 17 to control the main injection. The time t ₃ thus corresponds to a control start for the main injection, while the time t ₄ corresponds to a drive end for the main injection.

The course of the drive signal x influences the pressure curve in the combustion chamber. The drive signal x thus leads to the first pressure profile described above 81 , The steep sections of the first pressure curve 81 cause a relatively high proportion of high frequencies in the spectrum of the operating noise of the internal combustion engine. A relatively high proportion of these high frequencies is perceived as a hard operating noise of the internal combustion engine. The higher the proportion of these high frequencies in the operating noise of the internal combustion engine, the more pronounced is the characteristic of the harsh operating noise.

If this noise feature is too pronounced, then the control parameter t ₁ , ie the control start t ₁ for the pilot injection while maintaining the drive time τ is shifted to an earlier time t ₁ ', so that an altered first drive signal x' shown in the lower diagram results , In order to keep the drive duration τ constant, the drive end t ₂ is also shifted to an earlier time t ₂ '. This results in an increased time interval Δt '> Δt between the shifted drive end t ₂ ' of the pilot injection and the activation start t _{3 of} the main injection.

This change in the control start t ₁ while maintaining the activation duration τ for the pilot injection results in a second pressure curve 89 in the combustion chamber, in the upper diagram of the 4 indicated by dashed lines. It can be seen that the second pressure curve 89 in particular in the region of its maximum has a magnitude lower slope than the first pressure curve 81 , Because of these lower absolute slopes, the proportion of high frequencies on the spectrum of the second pressure curve 89 caused operating noise of the internal combustion engine 19 reduced. The operating noise is thus perceived as less hard, ie as a softer operating noise. The noise characteristic "roughness" is less pronounced. Probable in the inventive process control allows the start time t ₁ of the pilot injection is always selected so that the feature of the roughness of the operating noise of the internal combustion engine independently of the environmental conditions and the age of the internal combustion engine in the desired Extent in the operating noise is present.

In the embodiment shown, the method is effective 51 only in the control start t ₁ and - to maintain the drive duration τ for the pilot injection - in the Ansteuerende t ₂ for the pilot injection on. Deviating from this, in another Embodiment, the duration τ of the pilot injection to be changed. Furthermore, the times t ₃ and / or t ₄ can also be varied as a function of the feedback microphone signals s ₁ and s ₂ , so that an initial time and a duration of the main injection change. Furthermore, it is also possible to provide a plurality of pre-injections whose starting times and durations are determined by means of the method 51 can be regulated.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• EP 0416265 B1 [0002]

Claims (12)

Procedure ( 51 ) for operating an internal combustion engine ( 19 ), which at least one fuel injection valve ( 17 ) for injecting fuel into a combustion chamber of the internal combustion engine ( 19 ), wherein at least one control parameter (t ₁ ) for controlling the injection valve ( 17 ) in response to at least one feedback signal (s ₁ , s ₂ ), the an audible operating noise of the internal combustion engine ( 19 ) is characterized, characterized in that at least one noise feature of a desired operating noise of the internal combustion engine ( 19 ) ( 55 ) and the at least one drive parameter (t ₁ ) is regulated in such a manner in dependence on the feedback signal (s ₁ , s ₂ ) that at least one noise characteristic of the audible operating noise is adjusted to the predetermined noise characteristic of the desired operating noise. Procedure ( 51 ) according to claim 1, characterized in that an actual parameter set (V) is determined from the feedback signal (s ₁ , s ₂ ) ( 59 ) characterizing the at least one noise characteristic of the audible operating noise. Procedure ( 51 ) according to claim 2, characterized in that a desired parameter set (Y), which characterizes the at least one predetermined noise characteristic of the desired operating noise, is predetermined and in the case of a difference between the desired parameter set (Y) and the actual parameter set (V) the at least one actuation parameter (t ₁ ) is varied. Procedure ( 51 ) according to claim 3, characterized in that the desired parameter set (Y) from a set of different predefined target parameter sets ( 35 ) ( 55 ) becomes. Procedure ( 51 ) according to one of claims 2 to 4, characterized in that for determining ( 59 ) of the actual parameter set (V) - the returned signal (s ₁ , s ₂ ) is filtered ( 65 ), at least one time-frequency pattern is detected by means of a wavelet analysis ( 67 ), - at least one specific frequency is detected by means of a spectral analysis ( 69 ) and / or - at least one pattern in the time domain of the signal is detected ( 71 ) becomes. Procedure ( 51 ) according to one of the preceding claims, characterized in that the at least one control parameter to a control start (t ₁ ) and / or a drive duration (τ) when driving the injection valve ( 17 ) for at least one injection process, preferably a pre-injection corresponds. Procedure ( 51 ) according to one of the preceding claims, characterized in that the feedback signal (s ₁ , s ₂ ) with at least one microphone ( 23 . 27 ) is detected. Procedure ( 51 ) according to one of the preceding claims, characterized in that the at least one control parameter (t ₁ ) is regulated as a function of a further operating noise and / or ambient noise of a motor vehicle. Fuel system ( 11 ) for an internal combustion engine ( 19 ), which at least one fuel injection valve ( 17 ) for injecting fuel into a combustion chamber of the internal combustion engine ( 19 ) and at least one control device ( 15 ) for driving the fuel injection valve ( 17 ), characterized in that the control device ( 15 ) for carrying out the method ( 51 ) is programmed according to one of the preceding claims. Fuel system ( 11 ) according to claim 8, characterized in that the fuel system ( 11 ) first microphones ( 23 ) for receiving an audible operating noise of the internal combustion engine ( 19 ) having. Fuel system ( 11 ) according to claim 9 or 10, characterized in that the fuel system ( 11 ) second microphones ( 27 ) for receiving at least one further operating noise and / or at least one ambient noise of a motor vehicle. Fuel system according to claim 10 or 11, characterized in that at least one of the two sound recording means at least one microphone ( 23 . 27 ) and / or at least one signal processing arrangement ( 25 . 29 ) for conditioning a microphone ( 23 . 27 ) recorded microphone signal (s ₁ , s ₂ ).