DE10043106B4 - Method, computer program and control and / or regulating device for operating an internal combustion engine - Google Patents

Abstract

method for controlling an internal combustion engine (10) with at least one Combustion chamber (12) and with an accelerator pedal (36), wherein the fuel in the combustion chamber (12) is injected directly and the ignition angle to Knock prevention after late can be adjusted, characterized in that the angular position of the accelerator pedal (36) is detected by an angle sensor (38) that over the from the angle sensor (36) provided signal the movement speed (dwped_w) of the accelerator pedal (36) is determined, and that at least in an operating state of the internal combustion engine (10) then an adjustment (B_drlkrdy) of the ignition angle after late takes place when the movement speed (dwped_w) of the accelerator pedal (36) exceeds a threshold (dyespv).

Description

State of technology

The The present invention relates to a method for controlling a Internal combustion engine with a combustion chamber and with an accelerator pedal, at the fuel is injected directly into the combustion chamber and the firing angle To prevent knocking late adjusted become.

One Method of the type mentioned is known from the market. With him, the fuel is directly via a arranged on the combustion chamber Injection valve injected into this. In this way, throttle losses be avoided, which lowers the fuel consumption of such an internal combustion engine. In certain operating situations, such an internal combustion engine tend to a so-called "knocking". this includes is a premature and uncontrolled combustion of fuel understood in the combustion chamber, which occurs in particular when the internal combustion engine is very hot. In such cases can fuel injected into the combustion chamber before the actual ignition on the hot walls of the Igniting combustion chamber and lead to a pre-combustion. This is e.g. avoided by the fact that the ignition angle is retarded becomes. By such a retardation the gas temperature is lowered in the combustion chamber, resulting in a cooling of the Combustion chamber walls and subsequently to a reduction in the risk of spontaneous combustion leads.

The DE 37 21 424 C2 describes a method of operating an internal combustion engine, in which the ignition timing is adjusted depending on the rate of change of the opening state of a throttle valve. The DE 197 43 248 A1 describes a direct injection type internal combustion engine in which, with a combustion state detecting means, a deterioration of the combustion is detected and the ignition timing is to be influenced depending thereon.

A Adjustment of the ignition angle should be late However, only in those situations occur in which a knocking Combustion in the combustion chamber is to be expected. This is e.g. then the Case when the internal combustion engine is operated highly dynamically, when from her suddenly a higher one Load is required.

The The present invention has for its object a method of the beginning so-called type in such a way that a knocking combustion in the combustion chamber of the internal combustion engine even in such highly dynamic Situations can be safely avoided.

Advantages of invention

These The object is achieved in the aforementioned method in that the angular position of the accelerator pedal detected by an angle sensor will that over the signal provided by the angle sensor is the speed of movement of the accelerator pedal is determined, and that in an operating condition the engine then takes an adjustment of the firing angle after late, when the speed of movement of the accelerator pedal exceeds a threshold.

The inventive method assumes that a sudden increase the load is present when the accelerator pedal by the user with very high Speed pushed through becomes. It should be noted at this point, that the term "gas pedal" of course not to be understood in the narrow sense. Instead, all of them are below Facilities understood by which the user his performance requirement the control of the internal combustion engine tells, this may be around an accelerator pedal, a throttle or also e.g. to act on a throttle.

One sudden To press the accelerator pedal according to the invention then exists when the movement speed the accelerator pedal exceeds a limit. The limit value is chosen that when crossing the same the power provided by the internal combustion engine more or less so abruptly increases that with high probability a knocking during combustion in the combustion chamber of the internal combustion engine occurs. Now, if the movement speed of the accelerator pedal greater than the limit is already the firing angle after late adjusted, becomes reliable prevents then when the internal combustion engine to the suddenly changed power requirement by a sudden power change it actually reacts to a knocking combustion in the combustion chamber of the internal combustion engine comes.

advantageous Further developments of the invention are specified in subclaims.

For example, it is proposed that the accelerator pedal-based adjustment of the ignition angle takes place only in a fuel-guided operating state of the internal combustion engine. The background to this is as follows: There are essentially two ways to change the torque of an internal combustion engine: In the so-called "air-driven" system, a throttle valve is opened to increase the torque of the internal combustion engine. This increases the air charge in the combustion chamber of the internal combustion engine. The increased air charge is in turn measured by a sensor arranged in the intake manifold (HFM sensor), and in the combustion chamber then an amount of fuel corresponding to the air charge is injected.

at the second possibility the change takes place the torque of the internal combustion engine via a fuel-guided system. In this case, the throttle is usually fully open. An increase in the Torque of the internal combustion engine is increased by increasing injected fuel quantity causes. The air filling is in this fuel-guided System almost always maximum. This in turn means that the fuel-air mixture in the combustion chamber when fuel-driven System mostly not substantially stoichiometric, but lean is.

While one power change with the air-driven System because of the long controlled system (accelerator - throttle - HFM sensor - injection) with a certain time delay, it is the fuel-guided system because of the relatively short controlled system (accelerator - injection) quite spontaneous. Furthermore is the air filling when fuel-driven System approximately constant, allowing it to detect changes in performance not suitable.

Therefore lends itself to being fueled Operating state of the internal combustion engine, the gas pedal-based invention Adjustment of the ignition angle after late especially because here independent from the filling the combustion chamber a change the torque of the internal combustion engine immediately recognized and the corresponding measure can be initiated to prevent knocking.

In Further development of this variant of the invention is also proposed that the gas pedal-dependent Displacement of the ignition angle essentially only in such an operating state of the internal combustion engine takes place in which the fuel-air mixture in the combustion chamber is not in Substantially stoichiometric is (i.e., lambda> 1) and in particular in such an operating state of the internal combustion engine takes place, in which the fuel-air mixture in the combustion chamber layered is present.

Under a stratified fuel-air mixture is understood that only in the area of the spark plug an ignitable fuel-air mixture is present, in the from the spark plug However, only a relatively lean Mixture up to pure air is present.

One homogeneous-lean fuel-air mixture with a lambda to approx. 1.5 can be effected by an injection in the intake stroke. Yet leaner heterogeneous mixtures can et al also be provided by a double injection: Here will be first a small amount of fuel so injected into the combustion chamber that they are essentially homogeneously distributed in this one. Later will again injected a lot of fuel into the combustion chamber, which, however, layered essentially in the area of the spark plug remains. In both cases becomes a torque change the engine at generally fully open throttle and in about constant air filling by a change the injected fuel quantity causes, so here is the Gaspedalbasierte adjustment of the ignition angle for knock avoidance also very good.

Also according to the invention then an adjustment of the ignition angle after late take place when the speed of change of air filling in the combustion chamber exceeds a limit. As already stated above can be a change of the Torque of the internal combustion engine also by a change the air filling in the combustion chamber, ie by changing the throttle angle, be effected. By this one understands the said "air-led" system.

As usual Internal combustion engines operated in different modes can be i.e. air out and fuel-led, allows this development of the invention an optimal detection of a change of the Torque and allows thus avoiding knocking in all relevant operating modes Combustion necessary measures initiate. Basically, depending on the operating mode (fuel or air-guided) between pedal-based or air-fill based Ignition timing switched.

In Further development of this variant of the invention is also proposed that the air-fill-dependent shift the ignition angle only takes place when the fuel-air mixture in the combustion chamber substantially stoichiometric is present. Such a stoichiometric Fuel-air mixture is generally in the air-borne Operating mode of the internal combustion engine before.

According to the invention is further the shift of the ignition angle after a certain number of crankshaft revolutions again reversed. This measure wears the Fact bill that in dynamic operation the risk of knocking Burning only during a sudden torque change occurs. The shift of the ignition angle can therefore be limited to this, for the most part, very short period, which does not take more than a few crankshaft revolutions.

In a further development of the method according to the invention, the limit of the Gaspe depends dalgeschwindigkeit, from which the ignition angle is retarded, from the speed of the crankshaft of the internal combustion engine and / or the temperature of the internal combustion engine from. This is due to the fact that the tendency of the fuel to a knocking combustion depends on the one hand on the rotational speed of the crankshaft and on the other hand on the temperature of the internal combustion engine. At high speed and / or low temperature of the engine, the probability of dangerous knocking is lower, so that the corresponding limit may be higher.

Especially preferred is that development of the method according to the invention, in which two limit values are provided, which are defined by a Offset to achieve a hysteresis. It is special Cheap, if the offset depends on the speed.

The The invention also relates to a control and / or regulating device for Operating an internal combustion engine comprising a memory, on which a computer program is stored, which is used to execute a programmed the above method.

following is an embodiment of Invention with reference to the accompanying drawings in detail explained. In the drawing show:

1 a block diagram of an internal combustion engine; and

2 a flowchart of a method for operating the internal combustion engine of 1 ,

In 1 an internal combustion engine carries the reference numeral 10 , It includes a combustion chamber 12 , the fuel via an injection valve 14 is fed directly. The fuel is through a spark plug 16 ignited, which of an ignition system 18 is fed.

The combustion chamber 12 Air is via an inlet valve, not shown, from an intake manifold 20 fed. In the intake pipe 20 There is a chamber in which a throttle 22 is arranged. The adjustment of the throttle 22 done by a servomotor 24 , The internal combustion engine 10 also includes a crankshaft 26 ,

Furthermore, a control and regulating device 28 is provided, which receives signals from multiple sensors: This includes first a speed sensor 30 , the speed of the crankshaft 26 picks up and sends appropriate signals to the control and Regelgeät 28 emits. Furthermore, a position transmitter 32 provided the position of the throttle 22 detected. About a hot-film air flow meter 34 (HFM sensor) is the through the intake pipe 20 in the combustion chamber 12 flowing air mass detected.

In the control unit 28 becomes the corresponding signal, the air filling in the combustion chamber 12 determined. The angular position of an accelerator pedal 36 finally, by an angle sensor 38 detected, which also on the input side with the control and regulating device 28 connected is. On the output side, there is the control and regulating device 28 Control signals to the servomotor 24 , the injection valve 14 and the ignition system 18 out.

In the control and regulating device 28 is a store 40 present, preferably a flash memory in which a computer program is stored. By this computer program, a method for operating the internal combustion engine 10 realized below with reference to 2 is explained:
First, it will be explained how a knocking in the air-guided operation of the internal combustion engine 10 avoided: From the signals of the HFM sensor 34 and the positioner 32 the throttle 22 is in the control unit 28 not shown here on the one hand an actual air filling rl (block 42 ) in the combustion chamber 12 certainly. On the other hand, an actual load gradient drl_w and a predicted load gradient drlp_w are determined therefrom in cooperation with a timer (not shown) (blocks 44 and 46 ). These load gradients are therefore the change in the air charge per unit of time in the combustion chamber 12 , ie the speed of change in the air charge rl in the combustion chamber 12 , To switch between the actual filling gradient drl_w and the predicted filling gradient drlp_w in the block 48 serves a codeword CWKR in the block 50 ,

From the speed nmot (block 52 ) coming from the tachometer 30 is provided in the block 54 a speed reference point distribution SNM16KRUB intended. In the same way is from the in the block 52 certain air filling rl in the block 56 a support point distribution SRL04DYUB for the relative filling determined. These interpolation point distributions are in turn in the blocks 58 and 60 in maps KFDYES or KFDYESOF fed.

On the output side is in the map KFDYES in block 58 a limit dyesv (block 62 ) and in the map KFDYESOF (block 60 ) an offset dyesofv (block 64 ) certainly. In the block 66 the offset dyefofv is added to the limit value dyesv. In the blocks 68 and 70 Now, a comparison of the limit values of dyesv or Dyestuffs and Dyesofv with a filling gradient drlkrmx (Block 72 ), which is determined as follows.

As background, it is first pointed out that the determination of the filling gradient drl_w or of the predicted filling gradient drlp_w takes place synchronously with the rotational speed nmot, whereas the comparison in the blocks 68 and 70 in a certain clock, for example to the clock of 10 ms, takes place. At low speed, where only one value for the filling gradient is determined per cycle, the corresponding filling gradient drl_w or drlp_w becomes directly the value drlkrmx for the comparison in the blocks 68 and 70 used. At high speed, however, the bit B_drknv (block 73 ) during the last bar in the block 74 occurred maximum value drlkrmx from several filling gradients for the comparison in the blocks 68 and 70 used.

Is the result of the comparison in the block 68 "true", that is, the filling gradient drlkrmx is greater than the thresholds of the colorsv, a corresponding signal is in the switch 76 fed. Is the internal combustion engine 10 in the operating mode 10 "homogeneous", the fuel is through the injector 14 in the combustion chamber 12 So injected so that it is uniform in the combustion chamber 12 is distributed and a stoichiometric air-fuel ratio or lambda is set equal to or less than 1, this is by a bit B_hom (block 78 ) and the switch 76 placed so that a bit B_drlkrdy (block 80 ) (assuming the result in the block 68 is true.

This bit indicates to the controller that the firing angle should be retarded to avoid knocking. Is also the answer in the block 70 "true", that is, the limit exceeded by the offset dyesofv is exceeded, is analogous to the above, in the switch 81 a bit B_drlkrdyof set. This indicates that the adaptation of the ignition timing is enabled early.

The method described above, as stated above, then used when the internal combustion engine 10 works in homogeneous mode. In this operation, the torque of the internal combustion engine 10 by the position of the throttle 22 controlled, which in turn a corresponding change in the air filling rl in the combustion chamber 12 entails.

Depending on the air charge rl in the combustion chamber 12 will be such a lot of fuel in the combustion chamber 12 through the injector 14 injected a stoichiometric fuel-air mixture 12 is present. Such an operating mode is also referred to as "air-guided". By the method described is then when the air filling in the combustion chamber 12 suddenly changes, so if eg the throttle 22 suddenly opens, a corresponding bit B_drlkrdy or B_drlkrdyof (blocks 80 and 82 ), which retards the firing angle and thereby prevents knocking.

In the 1 illustrated internal combustion engine 10 However, it can also work in a fuel-guided operating state, preferably in stratified operation. In this is the throttle 22 essentially completely open, the combustion chamber 12 the internal combustion engine 10 is therefore always filled with air. A change in the torque of the internal combustion engine 10 is in this case caused by a corresponding amount of fuel through the injection valve 14 in the combustion chamber 12 is injected. Because the air filling in the combustion chamber 12 is essentially always constant, it can not be used to detect a change in performance at which knocking combustion can occur. Is the internal combustion engine 10 in such an operating condition, the procedure is therefore as follows:
About that of the angle sensor 38 The signal provided is the speed of movement dwped_w of the gas pedal 36 in the block 84 determined. From the speed-dependent interpolation point distribution SNM16KRUB (block 54 ) is displayed in a characteristic KRDYESP (block 86 ) a threshold dyespv (block 88 ) for the speed of movement of the accelerator pedal 36 certainly. This is on the one hand again a comparison block 90 supplied directly and on the other hand with the offset dyesofv in the block 92 added and another comparison block 94 fed.

Is the result of the comparison in the block 90 "true", that is the speed of movement dwped_w of the gas pedal 36 greater than the threshold dyespv (block 88 ) and is the internal combustion engine 10 not in the homogeneous mode, which is indicated by the bit B-hom (block 78 ) is not set and the switch 76 is set accordingly, then the bit B_drlkrdy in the block 80 set and thereby retarded the ignition angle to avoid knocking combustion. The same applies to the B_drlkrdyof bit in the block 82 ,

In this way, so also in an operating mode of the internal combustion engine 10 in which an increase in the performance of the internal combustion engine 10 directly through the amount of through the injector 14 in the combustion chamber 12 the internal combustion engine 10 injected fuel ensures safe prevention of knocking combustion in a sudden power increase. Depending on the operating mode (fuel-guided or air-guided), a switch is therefore made between a pedal-based and an air-fill-based ignition angle adjustment.

It should be noted that in principle in the air-controlled mode of the Internal combustion engine 10 preferably with a stoichiometric mixture, the knock prevention could be carried out by gas pedal. Since in this mode of operation, the actual increase in the power of the internal combustion engine 10 but only delayed for the movement of the gas pedal 36 takes place as an opening of the throttle 22 due to the compressibility of the air and the frictional flow in the intake manifold 20 not immediately a changed filling in the combustion chamber 12 As a result, such accelerator pedal-based knock prevention in the air-guided operation of the internal combustion engine 10 lead to too early adjustment of the ignition angle.

The method described above therefore ensures that in each operating mode of the internal combustion engine 10 whether fuel-led or air-led, the adjustment of the ignition angle takes place at just the right time. The speed-dependent interpolation point distribution SNM16KRUB (block 54 ) allows a speed-dependent adjustment of the ignition angle to late. Alternatively or additionally, the temperature of the internal combustion engine 10 be used to determine the limit value of dyesv. The same applies to the offset dyesofv.

Claims (11)

Method for controlling an internal combustion engine ( 10 ) with at least one combustion chamber ( 12 ) and with an accelerator pedal ( 36 ), in which fuel in the combustion chamber ( 12 ) is injected directly and the ignition angle for knock prevention can be retarded, characterized in that the angular position of the accelerator pedal ( 36 ) from an angle sensor ( 38 ) that is detected by the angle sensor ( 36 ) provided signal the speed of movement (dwped_w) of the accelerator pedal ( 36 ) is determined, and that at least in an operating state of the internal combustion engine ( 10 ) then an adjustment (B_drlkrdy) of the ignition angle takes place late when the movement speed (dwped_w) of the accelerator pedal ( 36 ) exceeds a threshold (dyespv). A method according to claim 1, characterized in that the gas pedal-dependent displacement (B_drlkrdy) of the ignition angle only in a fuel-guided operating state of the internal combustion engine ( 10 ) he follows. Method according to one of claims 1 or 2, characterized in that the accelerator pedal-based adjustment (B_drlkrdy) of the ignition angle to late substantially only in such an operating state of the internal combustion engine ( 10 ) takes place, in which the fuel-air mixture in the combustion chamber ( 12 ) is not substantially stoichiometric, and in particular takes place in such an operating state of the internal combustion engine, in which the fuel-air mixture ( 10 ) in the combustion chamber ( 12 ) is layered. Method according to one of the preceding claims, characterized in that at least in an operating state of the internal combustion engine ( 10 ) an adjustment (B_drlkrdy) of the ignition angle takes place late when the speed (drl_w) of the change in the air charge (rl) in the combustion chamber ( 12 ) exceeds a threshold (Dyesy). A method according to claim 4, characterized in that the air-filling-dependent displacement (B_drlkrdy) of the ignition angle only in an air-guided operating state of the internal combustion engine ( 10 ) he follows. Method according to one of claims 4 or 5, characterized in that the air-filling-dependent displacement (B_drlkrdy) of the ignition angle only in such an operating state of the internal combustion engine ( 10 ) takes place, in which the fuel-air mixture in the combustion chamber ( 12 ) is substantially stoichiometric. Method according to one of the preceding claims, characterized characterized in that the displacement of the ignition angle after a certain number is reversed by crankshaft revolutions. Method according to one of the preceding claims, characterized in that the limit value (dyespv) of the accelerator pedal speed (dwped_w), from which the ignition angle is retarded, of the rotational speed (nmot) of the crankshaft ( 26 ) of the internal combustion engine ( 10 ) depends. Method according to one of the preceding claims, characterized characterized in that two limit values are provided, which are distinguish by an offset (dyesofv) to achieve hysteresis. Method according to claim 9, characterized in that that the offset (dyesofv) depends on the speed (nmot). Control and / or regulating device for operating an internal combustion engine ( 10 ), characterized in that it has a memory ( 40 ), on which a computer program is stored, which is programmed to carry out the method according to one of claims 1 to 10.