EP1099051B1 - Method for operating an internal combustion engine - Google Patents

Description

State of the art

The invention relates to a method for operating a Internal combustion engine, in particular of a motor vehicle, at the fuel either in a first mode of operation a compression phase or in a second operating mode directly into a combustion chamber during an intake phase is injected in between the two Operating modes is switched, and in which the given torque influencing the internal combustion engine Company sizes depending on a requested Moment different in the two operating modes controlled and / or regulated. Furthermore concerns the invention is an internal combustion engine in particular for a Motor vehicle, with an injection valve, with the Fuel either in a first mode during a compression phase or in a second operating mode directly into a combustion chamber during an intake phase is injectable, and with a control unit for switching between the two modes of operation and different Control and / or regulation in the two operating modes of the the delivered torque of the internal combustion engine influencing operating variables depending on one requested moment.

Such systems for the direct injection of fuel are in the combustion chamber of an internal combustion engine, for example US-A-5,078,107. It will be the first Operating mode a so-called stratified charge mode and as second mode of operation is a so-called homogeneous operation distinguished. Stratified charge operation is particularly used for smaller loads during homogeneous operation with larger loads applied to the internal combustion engine is used.

In stratified charge mode, the fuel is used during the Compression phase of the internal combustion engine in the combustion chamber injected such that at the time of ignition a Cloud of fuel in the immediate vicinity of a spark plug located. This injection can be different Way. So it is possible that the injected Fuel cloud is already during or immediately after the injection is at the spark plug and from this is ignited. It is also possible that the injected cloud of fuel through a charge movement the spark plug is guided and only then ignited. at the two combustion processes are not uniform Fuel distribution before, but a stratified charge.

The advantage of stratified charge operation is that there with a very small amount of fuel applied smaller loads from the internal combustion engine can be executed. Larger loads can, however cannot be fulfilled by stratified charge operation.

In homogeneous operation intended for such larger loads the fuel is during the intake phase of the Internal combustion engine injected so that a swirl and thus a distribution of the fuel in the combustion chamber can still be done easily. To that extent corresponds to Homogeneous operation such as the operation of Internal combustion engines in the conventional way Fuel is injected into the intake pipe. If necessary can operate even with smaller loads be used.

In stratified charge operation, the throttle valve is closed the intake pipe leading the combustion chamber wide open and the Incineration is essentially only through the Fuel mass to be injected controlled and / or regulated. In homogeneous operation, the throttle valve is in Dependent on the requested moment opened or closed and the fuel mass to be injected is in Controlled depending on the intake air mass and / or regulated.

In both operating modes, i.e. in stratified charge mode and in homogeneous operation, the fuel mass to be injected depending on a number of others Company sizes on one with regard to Saving fuel, reducing emissions and the like optimal value controlled and / or regulated. The control and / or regulation is in the two operating modes differently.

In the case of control and / or regulation, direct injection Internal combustion engines must operate in either of the two modes be considered separately. Must also be guaranteed be that when switching in particular from the Homogeneous operation in the stratified charge operation of the Internal combustion engine torque remains constant.

The object of the invention is a method for operating to create an internal combustion engine, the one instantaneous changeover from the second to the first Operating mode enabled.

This task is carried out in a process or in a Internal combustion engine of the aforementioned invention solved in that in the first mode fuel mass to be injected depending on a Lambda controller factor of the second operating mode and in Dependence on others, the injections of the second Operating mode underlying operating parameters of the Internal combustion engine is determined.

Through the use of operating variables of homogeneous operation in the control and / or regulation of the Stratified charge operation creates the possibility that when switching from homogeneous operation to Stratified charge operation due to a changeover Differences in torque can be avoided. With that the Smooth running of the internal combustion engine and comfort for the Driver of the motor vehicle increased and a constant torque when switching from homogeneous operation to Stratified charge operation reached.

Furthermore, the control and / or regulation of the Stratified charge operation based on the control and / or regulation of homogeneous operation. This results in the advantage that the control and / or regulation of the Homogeneous operation, especially the necessary Software modules or the like, from known Internal combustion engines can only be taken over in Homogeneous operation. So it's just required the control and / or regulation for the new additional stratified charge operation to create this Control and / or regulation is then based on the known Software modules "put on", so that a total Control and / or regulation for a direct injection Internal combustion engine is created.

It is particularly advantageous if the lambda control factor by means of a time and / or speed-dependent characteristic curve is changed.

In an advantageous development of the invention the lambda controller factor of the second operating mode saved. This is a measure that a torque constant switching from stratified charge operation back into homogeneous operation.

In a further advantageous embodiment of the Invention will be in the first mode fuel mass to be injected depending on a Intake air temperature and / or an ambient pressure determined. This can be used to switch from Homogeneous operation in the stratified charge operation in the sense of a Constant torque can be further improved.

Figur 1

zeigt ein schematisches Blockschaltbild eines Ausführungsbeispiels einer erfindungsgemäßen Brennkraftmaschine eines Kraftfahrzeugs,

Figur 2

zeigt ein schematisches Ablaufdiagramm eines Ausführungsbeispiels eines erfindungsgemäßen Verfahrens zum Betreiben der Brennkraftmaschine der Figur 1, und

Figur 3

zeigt ein schematisches Ablaufdiagramm eines Teils des Verfahrens der Figur 2 im Detail.

In an advantageous development of the invention, the fuel mass to be injected in the first operating mode is determined as a function of the requested torque. It is particularly advantageous if the requested torque is changed by means of a speed-dependent characteristic curve and / or if the requested torque is changed as a function of a specific heating value of the fuel and / or an efficiency of the combustion of the internal combustion engine in the first operating mode.

Figure 1

shows a schematic block diagram of an embodiment of an internal combustion engine of a motor vehicle according to the invention,

Figure 2

shows a schematic flow diagram of an embodiment of a method according to the invention for operating the internal combustion engine of Figure 1, and

Figure 3

shows a schematic flow diagram of part of the method of Figure 2 in detail.

1 shows an internal combustion engine 1, in which a piston 2 in a cylinder 3 back and forth is movable. The cylinder 3 has a combustion chamber 4 provided, on the valves 5, an intake pipe 6 and Exhaust pipe 7 are connected. Furthermore are the Combustion chamber 4 can be controlled with a signal TI Injector 8 and a controllable with a signal ZW Spark plug 9 assigned.

The intake pipe 6 is with an air mass sensor 10 and that Exhaust pipe 7 can be provided with a lambda sensor 11. The air mass sensor 10 measures the air mass of the Intake pipe 6 supplied fresh air and generated in Depending on this, a signal LM. The lambda sensor 11 measures the oxygen content of the exhaust gas in the exhaust pipe 7 and generates a signal λ depending on this.

A throttle valve 12 is in the intake pipe 6 housed, whose rotational position by means of a signal DK is adjustable.

In a first operating mode, the stratified charge mode of the Internal combustion engine 1, the throttle valve 12 becomes wide open. The fuel is supplied from the injection valve 8 during one caused by the piston 2 Compression phase injected into the combustion chamber 4, namely locally in the immediate vicinity of the spark plug 9 and at a suitable distance before the ignition point. Then the fuel is ignited using the spark plug 9, so that the piston 2 in the now following working phase due to the expansion of the ignited fuel is driven.

In a second operating mode, the homogeneous operation of the Internal combustion engine 1, the throttle valve 12 in Dependence on the desired air mass supplied partially opened or closed. The fuel will from the injector 8 during one through the piston 2 induced suction phase in the combustion chamber 4 injected. Through the air sucked in at the same time the injected fuel swirls and thus in the Combustion chamber 4 is distributed substantially uniformly. After that the fuel / air mixture during the Compression phase compressed to then from the spark plug 9 to be ignited. By the expansion of the inflamed The piston 2 is driven by fuel.

In stratified charge mode as well as in homogeneous mode through the driven piston a crankshaft 14 in a Rotational movement over which ultimately the wheels of the Motor vehicle are driven. The crankshaft 14 is assigned a speed sensor 15 which is a function of the rotational movement of the crankshaft 14 generates a signal N.

The in stratified charge and homogeneous operation of the Injection valve 8 injected into the combustion chamber 4 Fuel mass is in particular from a control unit 16 in terms of low fuel consumption and / or controlled low pollutant development and / or regulated. For this purpose, the control unit 16 is equipped with a Microprocessor provided in a storage medium, a program especially in a read-only memory has saved, which is suitable for the named Control and / or regulation to perform.

The control unit 16 is acted upon by input signals, the operating variables measured by sensors Represent internal combustion engine. For example, that is Control unit 16 with the air mass sensor 10, the lambda sensor 11 and the speed sensor 15 connected. Furthermore is the control unit 16 with an accelerator pedal sensor 17 connected, which generates a signal FP, the position an accelerator pedal actuated by a driver and thus indicates the moment requested by the driver. The Control unit 16 generates output signals with which over Actuators the behavior of the internal combustion engine accordingly the desired control and / or regulation influenced can be. For example, the control unit 16 with the Injector 8, the spark plug 9 and the throttle valve 12 connected and generates the for their control required signals TI, ZW and DK.

The control unit 16 subsequently uses the Figures 2 and 3 described control method and / or regulation of homogeneous operation and one Stratified charge operation carried out. The in Figure 2 and 3 blocks shown represent functions of Process, which is for example in the form of Software modules or the like in the control device 16 are realized.

A block 20 is shown in FIG Torque coordination carried out. This means that from a plurality of input torque requests a so-called indexed moment mi is determined, the the entire torque required by the internal combustion engine 1 represents. For the torque requirements on the input side can be, for example, the signal FP, the is generated by the accelerator pedal sensor 17, and that of represents the moment requested by the driver.

The indicated moment mi is a filling control and / or control 21 supplied depending on the indicated moment mi and possibly a plurality further operating variables of the internal combustion engine 1 a signal DKhom generated that the control of the throttle valve 12 in Homogeneous operation is used. With the help of the filling control and / or control 21, the throttle valve 12 becomes such influences that the desired moment from the Internal combustion engine 1 is generated and delivered.

The signal DKhom is a fuel control and / or - control 22 supplied depending on the signal DKhom and other company sizes of Internal combustion engine 1 generates a signal mkhom, which of the fuel injector 8 to be injected Homogeneous operation corresponds. For the other company sizes can be, for example, a lambda controller factor for homogeneous operation LFhom and around adapted values AW act that are essential for homogeneous operation.

If the internal combustion engine 1 is in homogeneous operation, so a switch 23 is shown in the figure 2 Switched position for homogeneous operation. With that the signals DKhom and mkhom as control signals DK and mk for the throttle valve 12 and for the injection valve 8 passed. The signal mk, i.e. the one to be injected Fuel mass is still in a signal TI converted, which is then used to control the injection valve becomes.

The structure of the control described above and / or Regulation of the internal combustion engine 1 corresponds to that Control and / or regulation in the known Internal combustion engines is used only in Homogeneous operation. The known ones there Software modules or the like can therefore present control and / or regulation adopted and continue to be used.

If the internal combustion engine 1 described in Stratified charge operation, so the Switch 23 in the position shown in Figure 2 switched.

FIG. 2 shows a throttle valve control and / or Regulation 24 is provided, which may be dependent a signal from operating variables of the internal combustion engine 1 DKschicht generated, the switch 23 as signal DK is passed on to the throttle valve 12. This signal DKschicht serves to adjust the throttle valve 12 in Stratified charge operation.

In the throttle valve control and / or regulation 24 can it is, for example, a characteristic with which the signal DKschicht depending on the speed is determined. It is also possible that the signal DK layer depending on a differential pressure Throttle valve 12 is controlled and / or regulated. It is essential that the throttle valve 12 in Stratified charge operation is so wide open that the Internal combustion engine 1 from slightly dethrottled to completely can run dethrottled.

A correction block 25 is provided in FIG Dependence on the indicated moment mi and one A plurality of further input variables have a signal mkschicht generated that the fuel mass to be injected in Stratified charge operation. The switch is located 23 in the position for stratified charge operation, so the signal mkschicht as fuel mass mk to be injected passed on to the injector 8.

The indicated torque mi is supplied to a λ target-layer map 26, which is also subjected to the speed N of the internal combustion engine 1. The λ-target layer label 26 produces a signal λ _{to layer} depending on the indexed torque mi and the rotational speed N, which is used to correct a required due to, for example, an exhaust gas recirculation or tank vent throttling of the internal combustion engine. 1 Such throttling affects the torque generated and the air / fuel ratio. This influence is compensated for with the signal λ _{nominal layer} , in particular in the sense of a constant torque when switching from homogeneous operation to stratified charge operation.

The correction block 25 is shown in detail in FIG. 3. The correction _block 25 is _{supplied with} the signal λ _{nominal layer} , the indicated torque mi, the adapted values AW for homogeneous operation, the lambda controller factor LFhom for homogeneous operation, an intake air temperature ALT and an ambient pressure UD.

The Lamda controller factor LFhom for homogeneous operation is after switching to stratified charge mode saved and thus frozen. Regardless of that this lambda controller factor LFhom as a correction variable in the Fuel mass calculation for stratified charge operation used according to Figure 3.

According to FIG. 3, the lambda regulator factor LFhom is one Characteristic curve 27 supplied which is a time and / or speed-dependent influencing of the same carries out. This is particularly necessary if the known Control and / or regulation for homogeneous operation Load changes after an initial value for the lambda control requires a switch back to homogeneous operation. The changed lambda controller factor is then in this case as Initial value after switching to homogeneous operation used.

However, it is also possible that the lambda regulator factor Maintain LFhom in stratified charge mode becomes. In this case, a larger or smaller one fuel mass to be injected by changes in the Injection valve 8 are caused.

The output signal of the characteristic curve 27 is multiplicatively combined with the adapted values AW, the ambient pressure UD and the intake air temperature ALT in accordance with FIG. 3 to form a signal F. With the result of these multiplications, the signal λ _{nominal layer is} divided. The result of this division is fed to a block 28 of FIG. 3, which serves to take into account the difference in the efficiency of the homogeneous operation and the stratified charge operation.

In block 28, a correction factor Fkorr is determined from the division result of λ _{target layer} / F using a characteristic curve, which represents the efficiency difference mentioned between homogeneous operation and stratified charge operation. This correction factor Fkorr is subsequently used to correct the fuel mass to be injected in stratified charge mode.

This fuel mass to be injected is calculated according to FIG. 3 from the indicated moment mi in a block 29, specifically according to the equation K * mi / ηverbr * Hu. Here ηverbr corresponds to the combustion efficiency in stratified charge operation, Hu to the specific calorific value of the fuel and K to a constant.

The output signal of block 29, that is to say fuel mass to be injected is then multiplied linked with the correction value Fcorr. The output signal of the block 29, which so far only the efficiency of Stratified charge operation is taken into account in Dependence on the explained difference in efficiency between homogeneous operation and stratified charge operation corrected. It follows from that in Stratified charge fuel quantity to be injected mkschicht. As already mentioned, this signal mkschicht over the corresponding in stratified charge operation changed switch as fuel mass to be injected mk passed on to the injection valves 8.

Claims (8)

1. Method for operating an internal combustion engine (1), in particular of a motor vehicle, in which fuel is injected directly into a combustion chamber (4) either in a first operating mode during a compression phase or in a second operating mode during an induction phase, in which the engine is switched between the two operating modes, and in which the operating variables which influence the torque output by the internal combustion engine (1) are controlled differently in the two operating modes as a function of a required torque (mi), characterized in that the mass of fuel (mkschicht) which is to be injected in the first operating mode is determined as a function of a lambda controller factor (LFhom) of the second operating mode and as a function of further operating parameters of the internal combustion engine (1), on which the injections in the second operating mode are based.
2. Method according to Claim 1, characterized in that the lambda controller factor (LFhom) is changed by means of a time-dependent and/or speed-dependent characteristic curve (27).
3. Method according to one of Claims 1 or 2, characterized in that the lambda controller factor (LFhom) of the second operating mode is stored.
4. Method according to one of Claims 1 to 3, characterized in that the mass of fuel (mkschicht) which is to be injected in the first operating mode is determined as a function of an intake-air temperature (ALT) and/or an ambient pressure (UD).
5. Method according to one of Claims 1 to 4, characterized in that the mass of fuel (mkschicht) which is to be injected in the first operating mode is determined as a function of the required torque (mi).
6. Method according to Claim 5, characterized in that the required torque (mi) is changed by means of a speed-dependent characteristic diagram (26).
7. Method according to one of Claims 5 or 6, characterized in that the required torque (mi) is determined as a function of a specific calorific value (Hu) of the fuel and/or an efficiency (□verbr) of the combustion of the internal combustion engine (1) in the first operating mode.
8. Internal combustion engine (1), in particular for a motor vehicle, having an injection valve (8), by means of which fuel is injected directly into a combustion chamber (4) either in a first operating mode during a compression phase or in a second operating mode during an induction phase, and having a control unit (17) for switching between the two operating modes and for differently controlling, in the two operating modes, the operating variables which influence the torque output by the internal combustion engine (1) as a function of a required torque (mi), characterized in that the control unit (16) determines the mass of fuel (mkschicht) which is to be injected in the first operating mode as a function of a lambda controller factor (LFhom) of the second operating mode and as a function of further operating parameters of the internal combustion engine (1), on which the injections in the second operating mode are based.

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