JP2005537430A - Method for operating an internal combustion engine - Google Patents

Abstract

The invention defines in particular the break angle of fuel injection into the combustion chamber of an internal combustion engine of a motor vehicle, in which case, at the latest, the pressure in the combustion chamber is the other side of the injection valve for injecting fuel into the combustion chamber, More particularly, the present invention relates to a method for operating an internal combustion engine in which an interruption angle corresponds to a crank angle exceeding a pressure in an inflow pipe. According to the invention, the combustion chamber pressure is equalized with the intake pipe pressure in the intake stroke, defined in relation to the intake pipe pressure via compression in the compression stroke, and the combustion chamber pressure is defined as the pressure on the other side of the injection valve. Comparing and defining the differential pressure, interrupting the injection when the defined differential pressure is achieved, in this case the crank angle at which the injection is interrupted at the latest with a known intake pipe pressure and a known pressure on the other side of the injection valve Is defined as the break angle.

Description

BACKGROUND OF THE INVENTION The present invention defines in particular the break angle of fuel injection into the combustion chamber of an automobile internal combustion engine, in which case the pressure in the combustion chamber at the latest is the other of the injection valves for injecting fuel into the combustion chamber. The invention relates to a method for operating an internal combustion engine in which the break angle corresponds to the crank angle above the side, in particular above the pressure in the rail.

  Similarly, the present invention is a computer program for carrying out the method, a control device for controlling and adjusting the internal combustion engine, and an internal combustion engine itself particularly used in an automobile, provided with a combustion chamber, It relates to a type in which fuel can be injected into the room and the injection is controllable and / or adjustable via a control device.

  Such a method and this type of internal combustion engine are known, for example, by so-called “gasoline direct injection” in motor vehicles. There, fuel is injected into the combustion chamber of the internal combustion engine during the suction phase in homogeneous combustion operation or during the compression phase in stratified combustion operation. The homogeneous combustion operation is advantageously provided for full load operation of the internal combustion engine, whereas the stratified combustion operation is suitable for idling operation or part load operation. For example, in connection with the required torque, in such a direct injection type internal combustion engine, switching between the two operation modes described above is performed.

  In engines with direct gasoline injection, fuel is injected directly into the combustion chamber. Usually, fuel with high pressure is provided. This is because the high-pressure pump creates a high pressure in front of the high-pressure injector (injection valve), which causes a pressure decrease above the injection valve in the direction of the internal combustion engine. However, in certain operating conditions, it must be taken into account that the pressure of the fuel in the accumulator is slightly lower than the pressure created in the combustion chamber.

  Especially at the start-up phase, when the high-pressure pump has not yet developed sufficient pressure, the fuel is at a pressure level corresponding to the pressure level of the electric fuel pump, in particular in the rail or generally in the fuel inlet line. Has been granted. The internal combustion engine is started in a homogeneous combustion operation. In particular, during a cold start, a relatively long injection period can be required to inject the desired amount of fuel into the combustion chamber and reliably start the internal combustion engine based on the still slight pressure acting on the fuel. is there. For this reason, the injection continues as long as the internal combustion engine has already transitioned from the intake phase to the compression phase during the injection and the pressure formed in the combustion chamber thereafter is greater than the pressure acting on the fuel in the inflow line. Can be born. Within the combustion chamber, the pressure increases with increasing piston stroke in the compression stroke. In this case, a long injection time can cause fuel and gas to be blown back into the rail from the combustion chamber. This must be avoided anyway.

  There is also a diagnostic function that requires a reduction in pressure to the level of the electric fuel pump. Even in the stratified combustion operation in which the fuel is injected during the compression stroke, an operation state in which the combustion chamber pressure exceeds the fuel pressure in the rail in front of the injection valve or in the inflow conduit can be generated.

  Conventionally, in order to avoid gas blowing back into the rail, a characteristic map is provided that sets the break angle for injection only with respect to the formed rail pressure.

  The corresponding characteristic map for the injection interruption must be detected by individual measurements according to the known prior art.

  It is therefore known, for example, to propose a method for operating an internal combustion engine that is operated in two operating modes, as well as the internal combustion engine itself, based on DE 199 13 407 for example. In this internal combustion engine, fuel is injected into the combustion chamber. In this case, the injection has an injection start angle and an injection period. In this case, the injection end angle is detected from the injection start angle and the injection period, and in this case, it is inspected whether the injection interruption angle is exceeded by the injection end angle. If this is the case, the injection start angle is shifted towards the “early direction”.

  The object of the present invention is to improve the method for operating an internal combustion engine so that the optimal break angle can be described at all operating points and that data detection is significantly simplified. . This should ensure improved use of the provided time window for injection.

  According to the present invention, in the method described at the beginning, according to the present invention, the combustion chamber pressure is made equivalent to the intake pipe pressure in the intake stroke, and is defined in relation to the intake pipe pressure through the compression stroke. The pressure is compared with the pressure on the other side of the injection valve, the differential pressure is defined and the injection is interrupted when the specified differential pressure is achieved, in which case the known intake pipe pressure and the known pressure on the other side of the injection valve This is solved by defining the crank angle at which the injection is stopped at the latest as the interruption angle.

  With the proposed method, the break angle is detected relatively and with additional consideration of the intake pipe pressure. This makes it possible to define a remarkably accurate break angle. From the regulation of the combustion chamber pressure and the formation of the differential pressure above the injection valve, the required crank angle for interrupting the injection can finally be calculated. If the differential pressure becomes too small, injection is interrupted.

  In the compression stroke, the combustion chamber pressure is defined in relation to the intake pipe pressure, particularly via adiabatic compression. In contrast, the combustion chamber pressure is equalized to the intake pipe pressure in the intake stroke. In this way, the break angle can be defined more precisely, and therefore the provided injection window can be used better. As a result, a desired amount of fuel can be injected, and nevertheless, fuel blowback can be reliably prevented. The means according to the invention can be used in all operating conditions of the internal combustion engine and even during a cold start. Thus, a reliable starting of the internal combustion engine under all conditions is achieved.

  As a precaution, the time of belonging also corresponds to each angle described above and each angle described below. That is, all angles can be replaced by corresponding points in time or duration. In this case, the conversion is related to the rotational speed of the internal combustion engine.

  In this case, in the method, it may be proposed to define a special adiabatic compression in the combustion chamber via specific engine data and the current crank angle. The unique engine data can be detected in advance or can be provided by the manufacturer.

  In this case, when the conditional equation based on the crank angle is solved, a crank angle in which a pressure decrease exists in the direction of the combustion chamber is generated in the applied intake pipe pressure and the applied rail pressure. The theoretical break angle at ambient pressure can be detected using an equation for the adiabatic ratio, for example at the same ambient pressure as the intake pipe pressure and the current rail pressure. Multiplying with the actual intake pipe pressure gives the required break angle. The calculation can be simplified by describing the value for adiabatic compression at ambient pressure in the characteristic line and by subsequent multiplication of the angle and the intake pipe pressure.

  Furthermore, it may be proposed that the fuel injection is already interrupted at a crank angle located before reaching the interrupt angle by a predetermined safety angle.

  In this case, the pressure difference is adjusted differently, thus obtaining an earlier break angle and thus further increasing the safety that the fuel is not blown back into the rail.

  In particular, it may be proposed to use the method during a first operating mode in which the injection process is started during the intake stroke, ie in a homogeneous combustion operation. In this first operating mode of the internal combustion engine, the throttle valve is partially opened and closed in relation to the desired torque. The fuel is injected from the injection valve into the combustion chamber during the intake phase produced by the piston. At the same time, the injected fuel is swirled by the air sucked through the throttle valve, and is distributed almost uniformly in the combustion chamber. The fuel / air mixture is then compressed during the compression phase and then ignited by a spark plug. The piston is driven by the expansion of the ignited fuel. The torque formed is mainly related to the position of the throttle valve in homogeneous combustion operation. With regard to slight toxic substance generation, the fuel / air mixture is adjusted as much as possible to λ (excess air) = 1 or λ <1.

  In another operating mode of the internal combustion engine, the so-called “homogeneous lean combustion operation”, fuel is injected into the combustion chamber during the intake phase, as in the homogeneous combustion operation. However, unlike homogeneous combustion operation, a fuel / air mixture may be produced with λ> 1.

  Furthermore, a third operation mode of the internal combustion engine, the so-called “stratified combustion operation” is known. In the third operation mode, the throttle valve is fully opened. The fuel is injected by the injection valve into the combustion chamber during the compression phase produced by the piston, and is also injected locally immediately around the spark plug and at an appropriate time interval from the point of ignition. . Thereafter, the fuel is ignited by the spark plug, whereby the piston is now driven by the expansion of the ignited fuel in a subsequent working phase. The torque formed is well related to the amount of fuel injected in stratified combustion operation. The stratified combustion operation is mainly provided for idling operation and partial load operation of the internal combustion engine.

  In some cases, further modes of operation are possible. Switching between the aforementioned operating modes of the internal combustion engine may be performed.

  The above-described homogeneous combustion operation, in which the use of the invention is particularly advantageous, is given especially in the starting phase.

  Likewise, it is particularly advantageous if the present invention is used at a pressure that acts on the fuel and is below the critical pressure.

  If it is detected that the injection end angle may exceed the break angle, it is possible to change the start of the injection angle, in which case the injection angle can be changed especially towards the "early direction" May be proposed. This makes the injection angle especially when the pressure acting on the fuel is small, for example less than the limit pressure, thereby interrupting and in some cases too little fuel can be applied for reliable operation of the internal combustion engine. Can be achieved. If the pressure acting on the fuel is high, the injection time will generally be so short that it is no longer necessary to interrupt.

  In this case, it may be proposed that a full calculation is no longer performed to save computation time.

  The use at the start of the internal combustion engine is particularly advantageous. This is because the pressure on the fuel is very small especially at the start, especially at the cold start, and particularly corresponds to the pressure in an electric fuel pump. At the same time, a large amount of fuel must be injected into the combustion chamber, which ensures a reliable start of the internal combustion engine. Therefore, the interruption of injection may cause the internal combustion engine to stop at the start. For this reason, it is particularly advantageous to prevent interruption of the injection when starting the internal combustion engine. This can be fully achieved with a particularly optimal use of the injection time window, as made possible by the present invention. Furthermore, it may also be proposed here that a change in the injection start angle is provided. This can further improve that the amount of fuel provided is completely injected into the combustion chamber. On the other hand, fuel blowback is prevented.

  Furthermore, the present invention relates to a computer program. In this case, when the computer program is executed by a computer, it is suitable for carrying out the method described above.

  In particular, a computer program may be stored in the memory.

  It is particularly important to implement the method according to the invention in the form of a control element, in particular provided for a control device for an internal combustion engine of a motor vehicle. In this case, the control device stores a program which can be executed by a microprocessor, in particular a computer, and which is suitable for carrying out the method according to the invention. That is, in this case, the present invention is realized by a program stored in the control device, and thus the control device including the program forms the present invention in the same manner as a method using a program suitable for implementation. ing. As a storage medium, in particular an electrical storage medium, such as a read only memory or a flash memory, can be used. The control device for control and regulation serves in particular to ensure switching between operating states of the internal combustion engine.

  Finally, the present invention is an internal combustion engine particularly used in an automobile, provided with a combustion chamber, capable of injecting fuel into the combustion chamber, and provided with a fuel injection device, the fuel injection device This is related to a type in which the fuel reaches the combustion chamber. In this case, the injection is controllable and / or adjustable via the control device, and it can be detected by the control device whether the break angle is passed during the injection and the injection has to be interrupted.

  In particular, the internal combustion engine may have a control device for adjusting or controlling in the manner described above.

  Further features, applicability and advantages of the present invention will become apparent from the following description of embodiments shown in the drawings. In this case, all the features described or illustrated form the subject of the present invention on its own or in any combination.

  FIG. 1 shows a block circuit diagram of an internal combustion engine provided with an injection insert used in the internal combustion engine according to the present invention. In this case, fuel is supplied from the tank 14 to the high-pressure fuel pump 10 via the fuel inflow passage 12. The fuel is pumped from the tank 14 into the fuel inflow passage 12 by an electric low pressure fuel pump 16. The pressure in the fuel inflow passage 12 is adjusted via an adjustment valve.

  The high pressure fuel pump 10 pumps fuel into the rail 20 via the high pressure line 18. Furthermore, this rail 20 is connected to an injection valve 22 formed here as a high-pressure injection valve. The rail 20 is provided with a pressure limiting valve 24 and a pressure sensor 26.

  Further, the internal combustion engine has a control device 28. This control device 28 takes over control and adjustment of the injection device.

  In the drawing, signal lines, power supply lines and the like are not shown.

  Further, in particular, a cylinder having a combustion chamber partitioned by a piston, an intake valve, and an exhaust valve is not shown. An intake pipe is connected to the intake valve, and an exhaust pipe is connected to the exhaust valve. In the region of the intake valve and the exhaust valve, the injection valve 22 and the spark plug enter the combustion chamber. Fuel can be injected into a combustion chamber (not shown) via the injection valve 22. The fuel in the combustion chamber can be ignited by the spark plug.

  A rotatable throttle valve is accommodated in an intake pipe (not shown). Air can be supplied to the intake pipe via the throttle valve. The amount of air supplied is related to the angular position of the throttle valve. A catalyst is provided in the exhaust pipe. This catalyst serves to purify the exhaust gas produced by the combustion of fuel.

  From the exhaust pipe, exhaust gas returning means is returned to the intake pipe. An exhaust gas return valve is accommodated in the exhaust gas return pipe. By this exhaust gas return valve, the amount of exhaust gas returned into the intake pipe can be adjusted.

  The piston is reciprocated by the combustion of fuel in the combustion chamber. This reciprocating motion is transmitted to a crankshaft (not shown), and torque is applied to the crankshaft.

  The control device 28 is loaded with an input signal. This input signal constitutes the operating amount of the internal combustion engine measured by a sensor. For example, the control device 28 is connected to an air mass sensor, an excess air ratio sensor (oxygen sensor), a rotation speed sensor, and the like. Furthermore, the control device is connected to an accelerator pedal sensor. The accelerator pedal sensor generates a signal indicating the position of the accelerator pedal that can be operated by the driver and thus the required torque. The controller 28 generates an output signal. This output signal can affect the characteristics of the internal combustion engine via an actuator or regulator. For example, the control device 28 is connected to an injection valve, a spark plug, a throttle valve, and the like, and generates a required signal for controlling these components.

  In particular, the control device 28 is provided for controlling and / or adjusting the amount of operation of the internal combustion engine. For example, the amount of fuel injected into the combustion chamber by the injection valve 22 is controlled and / or adjusted by the control device 28, in particular with respect to a small fuel consumption rate and / or a small amount of harmful substance generation. For this purpose, the control device comprises a microprocessor, in particular a computer. The microprocessor includes a storage medium. This storage medium stores a program suitable for carrying out the control and / or adjustment described above and thus operating the method according to the invention.

  In this way, different operating modes, for example the so-called “homogeneous combustion operation”, “homogeneous lean combustion operation” or “stratified combustion operation” mentioned above, can be adjusted.

  The pressure in the fuel inflow line 12 is the pressure provided by the fuel pump 16 in the case of homogeneous combustion operation, such as that applied during internal combustion engine startup, particularly during cold start. The high pressure pump 10 has not yet supplied a pressure increase at this point. In this case, the pressure is located in the fuel inlet line 12 between 4 and 8 bar.

  In the homogeneous combustion operation in which fuel is injected into the piston by the injection valve 22 during the piston intake phase, pressure in the intake pipe is formed in the combustion chamber during the intake stroke. In this case, the intake pipe pressure is located between 0.7 and 1 bar in the starting stage. In this respect, the pressure in the rail 20 is greater than the pressure in the piston. However, in the start-up phase, the injection period is relatively long based on the slight pressure in the rail 20, so that this injection period can certainly start in the intake stroke, but it can occur that the compression stroke is reached. In this case, in this compression stroke, the pressure in the piston increases starting from the intake pipe pressure during the course of adiabatic compression, so that this pressure is greater than the pressure in the fuel inflow line and the pressure in the rail. Can be. In this case, fuel and gas can be blown back into the rail 20 through the injector valve 22. In order to prevent this, an interruption angle corresponding to the crank angle at which the compression is progressing is detected so that the pressure in the piston exceeds the pressure in the rail 20 in the starting stage.

  Furthermore, it can be proposed that a limit pressure is defined on the rail side and that the interrupted crank angle is detected only as long as the pressure in the rail 22 is smaller than this limit pressure. If the pressure in the rail 20 is increased by the high-pressure pump 10, in this case approximately 1000 bar can be achieved, blowback can no longer occur. Therefore, a limit pressure can be defined. After this limit pressure is exceeded, blowback can no longer occur.

  Therefore, it has been proposed that the combustion chamber pressure compared with the pressure on the rail side is detected in relation to the intake pipe pressure by adiabatic compression and the injection is interrupted when a defined differential pressure is achieved. In this case, at the known intake pipe pressure and the other side of the injection valve, that is, the known pressure in the rail, the crank angle at which injection is interrupted at the latest can be defined as the interrupt angle.

  Furthermore, a critical angle is detected as long as the break angle is exceeded during the injection, in which case an injection start angle is defined for this purpose, the injection period and in this regard the injection end angle. It can be proposed that the injection is already started earlier, so that the injection end angle does not pass the break angle after it has been detected.

  In this case, it can be proposed that the injection is interrupted, in particular, by a certain safety angle before the interruption angle.

  However, the method according to the invention makes it possible to more accurately define the critical crank angle by means of a better definition of the combustion chamber pressure, which makes better use of the time window provided for injection. Therefore, the injection start shift need not be done in many cases.

1 is a block circuit diagram of an embodiment of an internal combustion engine according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 High pressure fuel pump, 12 Fuel inflow path, 14 Tank, 16 Low pressure fuel pump, 18 High pressure pipe, 20 Rail, 22 Injection valve, 24 Pressure limiting valve, 26 Pressure sensor, 28 Control apparatus

Claims (12)

  In particular, it defines a break angle for fuel injection into the combustion chamber of an internal combustion engine of an automobile, in which case at least the pressure in the combustion chamber, at the latest, the other side of the injection valve for injecting fuel into the combustion chamber, in particular the inlet line In a method for operating an internal combustion engine in which an interruption angle corresponds to a crank angle exceeding the internal pressure, the combustion chamber pressure is made equal to the intake pipe pressure in the intake stroke, and is converted into the intake pipe pressure through compression in the compression stroke. The associated combustion pressure is compared with the pressure on the other side of the injection valve, the differential pressure is defined, and the injection is interrupted when the defined differential pressure is achieved, in which case the known intake pipe pressure and A method for operating an internal combustion engine, characterized in that at a known pressure on the other side of the injection valve, the crank angle at which injection is interrupted at the latest is defined as the interruption angle.   The method of claim 1 wherein the combustion chamber pressure is defined via adiabatic compression in the compression stroke.   3. A method according to claim 1 or 2, wherein a special adiabatic compression in the combustion chamber is defined via specific engine data and the current crank angle.   4. The method as claimed in claim 1, wherein the fuel injection is interrupted at a crank angle that is already positioned by a predetermined safety angle before reaching the interrupt angle.   The method according to claim 1, wherein the method is used in a so-called “homogeneous combustion operation”, in which the injection process is started during the first operating mode, in particular during the intake stroke.   6. The method as claimed in claim 1, wherein the method is used when the pressure in the inflow line acting on the fuel on the other side of the injection valve is less than the limit pressure.   7. The method according to claim 1, wherein the method is used when starting an internal combustion engine.   A computer program, characterized in that it is suitable for carrying out the method according to any one of claims 1 to 7 when said computer program is implemented on a computer.   9. Computer program according to claim 8, wherein the computer program is stored in a memory, in particular a read-only memory or a flash memory.   10. A control device for control and / or adjustment for operating an internal combustion engine particularly used in an automobile, wherein the control device and / or the adjustment device has a memory, and the memory comprises the memory according to claim 8 or 9. A control apparatus in which a computer program is stored.   In particular, an internal combustion engine used in an automobile, provided with a combustion chamber, fuel can be injected into the combustion chamber, a fuel injection device is provided, and the fuel is injected through the fuel injection device. Whether the injection is controllable and / or adjustable via a control device, the break angle is passed during the injection and the injection has to be interrupted in the type intended to reach the fuel chamber An internal combustion engine characterized in that the interruption angle can be detected and defined by the control device.   The internal combustion engine according to claim 11, wherein the internal combustion engine has the control device according to claim 10.

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