WO2009083470A1

WO2009083470A1 - Method for operating an internal combustion engine

Info

Publication number: WO2009083470A1
Application number: PCT/EP2008/067845
Authority: WO
Inventors: Claus Linsenmaier; Ruediger Weiss; Andreas Schmidt; Tobias Leutwein; Manfred Dietrich; Elias Calva
Original assignee: Robert Bosch Gmbh
Priority date: 2007-12-28
Filing date: 2008-12-18
Publication date: 2009-07-09
Also published as: DE102007063101A1

Abstract

Method for operating an internal combustion engine (10), wherein, during operation of the internal combustion engine (10) in a normal operating mode, an operation is carried out periodically in such a way that fuel is burnt in a combustion chamber (14) of the internal combustion engine (10) at a fixed angular position of a crankshaft (20) of the internal combustion engine (10), characterized in that during a starting process of the internal combustion engine (10) the operation is carried out independently of the fixed angular position.

Description

description

Title Method for operating an internal combustion engine

State of the art

The present invention relates to a method for operating an internal combustion engine, wherein during operation of the internal combustion engine in a normal operation, an operation for combustion of fuel in a combustion chamber of the internal combustion engine is performed periodically at a predetermined angular position of a crankshaft of the internal combustion engine. Furthermore, the present invention relates to a device which is set up for carrying out such a method and to a computer program for carrying out all the steps of such a method.

In internal combustion engines with direct injection, especially in internal combustion engines with gasoline direct injection, calculations of parameters or operating variables of the internal combustion engine are continuously made during operation in order to ensure a clean and economical combustion of fuel in the combustion chambers. These operations are also referred to as "tasks." They are used, for example, to calculate the charge, the amount of fuel in a stratified injection, the firing angle, and the ignition energy It is obvious that the amount of fuel required for injection must be calculated before injection.

In order to perform these operations in a suitable order and to ensure a smooth operation, it has proven to be useful to perform these operations at respectively fixed and partially different times or crankshaft rotation angles. In this way it is ensured that, for example, the filling with air of a combustion chamber is calculated before the required amount of fuel is calculated. Such methods and devices suitable therefor are described in detail in EP 1 283 343 A2. To synchronize or trigger the individual operations, a crankshaft-angle synchronization is established by placing a signal on the crankshaft. shaft fixed gear is observed with a tooth gap. A passing of the tooth gap provides information about the angular position of the crankshaft.

Conventionally, it is waited during start-up operations until a synchronization of a control device or a control method with the crankshaft angle takes place, i. H. It is waited until the tooth gap of the mounted on the crankshaft gearwheel is detected for the first time. Subsequently, in the prior art methods, the operations are started at the above-described specified times or crankshaft angles calculated from the synchronization based on the tooth gap. For this purpose, reference is again made to the above-mentioned European patent application.

A disadvantage of the described method is that it first has to wait until a synchronization has taken place, which in the unfavorable case requires almost a full revolution of the crankshaft before a synchronization can be performed. Furthermore, it is disadvantageous that the period between the synchronization and a first

Ignition of a mixture in a combustion chamber is additionally extended by the fact that the order described above must be observed.

Disclosure of the invention

An object of the invention is to improve the known from the prior art devices and methods, wherein in particular a method and an apparatus are to be given, which allow a faster starting an internal combustion engine, in particular an internal combustion engine with gasoline direct injection under high pressure.

This problem is solved by a method for operating an internal combustion engine, wherein during operation of the internal combustion engine in a normal operation, an operation for combustion of fuel in a combustion chamber of the internal combustion engine is performed periodically at a predetermined angular position of a crankshaft of the internal combustion engine, characterized in that during a startup of the internal combustion engine, the operation is performed independently of the fixed angular position. This means regardless of the fixed angular position in particular that for the calculation of an angular position is selected, which does not correspond to the fixed angular position or an angular position is selected, which corresponds to the fixed angular position, but this in the erfmdungs- according to the method is not mandatory. Furthermore, it should be understood that the operation is not necessarily tied to an angular position, but may also be triggered by the passage of a period of time or by comparable events. It should be noted that during the starting process, the internal combustion engine is towed, wherein the speed of the internal combustion engine in the starting process significantly below a

Speed of the internal combustion engine in normal operation is. If it is further taken into account that the normally determined angular positions for the operation are usually selected such that an operation is always ensured even when the internal combustion engine is operating at the maximum rotational speed, it becomes clear that a multiple of time is available during towing perform comparable calculations during a power stroke or one or two revolutions of the crankshaft. The method is particularly suitable for internal combustion engines with gasoline direct injection and in particular for internal combustion engines with a high-pressure gasoline direct injection from a high-pressure accumulator. Reference is made to EP 1 283 343 A2 for the usually defined angular positions for operations, which are also referred to as "tasks." This application also describes how synchronization with an angular identification mark, for example a tooth gap of a toothed wheel, The advantage of the invention is that synchronization by detecting, for example, a missing tooth gap of a gear fixed to the crankshaft is no longer decisive for the release of the injection and ignition.

Preferably, a known Abstellposition of the internal combustion engine is used to determine a first to be fired in the startup combustion chamber, wherein the operation for combustion in the first to be fired combustion chamber is performed regardless of the fixed angular position. A control device or a crankshaft, which is known after a shutdown of the internal combustion engine in which position, ie angular position, the crankshaft of the internal combustion engine, offer the advantage that even before a synchronization of a control device, the angular position of the crankshaft can be determined, which Combustion chamber is suitable for a first combustion of fuel. The parking position is also referred to as the rest position and usually denotes the angular position of the internal combustion engine immediately before towing. - A -

Preferably, the first combustion chamber to be fired is selected from a plurality of combustion chambers as a function of the parking position of the internal combustion engine. In the case of several existing combustion chambers of an internal combustion engine, it is generally after switching off the internal combustion engine that due to the position of the crankshaft, some pistons of combustion chambers are in a more favorable position for a subsequent fast high-pressure start than others.

Preferably, one of the most suitable combustion chambers or the most suitable combustion chamber is selected for an early first ignition of fuel during the starting process of the internal combustion engine.

Advantageously, as the first combustion chamber to be fired, a plurality of combustion chambers are selected which, in the parking position of the internal combustion engine, have sufficient charge for a first combustion in the starting process. With sufficient filling in this case is meant a sufficient air filling, d. H. a combustion chamber is selected which has a piston position as close as possible to the bottom dead center, so that there is a large amount of air in the combustion chamber. The size of the filling is decisive for whether one

Burning enough torque is built up to initiate the startup or continue. This offers the advantage that the ignition can be released as early as possible.

Advantageously, the first combustion chamber to be fired is determined prior to the start of the starting process of the internal combustion engine. In this case, before the start of the starting process, preferably before the towing of the internal combustion engine. Thus, for example, directly after switching off the internal combustion engine, the combustion chamber can be determined, which is best suited as the first combustion chamber to be fired in a subsequent starting process. In such a case, it is advantageous to monitor whether the crankshaft of the internal combustion engine is moved during the Abstellzeitraums, in such a case to switch to a conventional starting operation. Generally, in the context of the invention, it is preferable to switch to a conventional starting procedure if it is determined that the internal combustion engine is not in the stored parking position. Another possibility is to first determine the first combustion chamber to be fired, following a start request, and then to start to tow, ie, the actual starting procedure, of the internal combustion engine. This offers the advantage that at the beginning of towing it is already clear with which combustion chamber a first ignition of fuel is made. Advantageously, the first combustion chamber to be fired is one which is located in the exhaust chamber. in a compression tract or immediately before a compression tract.

Advantageously, the operation is performed independently of a synchronization of a control device by detecting an angle mark of the crankshaft. This offers the advantage that it is not necessary to wait for a synchronization and the starting process is accelerated. In other preferred embodiments of the invention, the operation is performed before synchronization of a control means follows by detecting an angular mark of the crankshaft. This means that the operation is started anyway, regardless of whether synchronization has already taken place. This does not rule out that, depending on the parking position of the internal combustion engine but a synchronization takes place before the calculation is started, for example, if the parking position of the type is that immediately after towing the angle mark is detected. In general, an angle mark is used to denote, for example, a tooth gap of a toothed wheel which is fastened to the crankshaft. The method offers the advantage that the synchronization by detecting an angle mark is no longer decisive for the release of the injection and ignition.

Preferably, a parameter is calculated during the operation. This parameter is advantageously an air filling quantity of the combustion chamber, a fuel quantity for the combustion chamber

Ignition angle or an ignition energy. In addition, other parameter calculations are possible or useful. The air filling quantity can be calculated, for example, from the angular position of the crankshaft by closing the current volume of the combustion chamber from the kinematic relationship between the crankshaft and the piston. The amount of fuel can be provided for a stratified injection. From the above-mentioned European application, various operations are known which must or can be performed to perform an injection. For details, refer to the above mentioned European application.

Advantageously, in a normal operation, a plurality of operations for combustion of fuel in a combustion chamber of the internal combustion engine are made periodically at different, fixed angular positions, wherein at least two of the operations are performed independently of the respectively fixed angular positions during the starting process. It can also be provided that operations in a different order than usually carried out, for example, because in the startup dependencies need not be considered, which must be considered in general operation. Furthermore, it is possible to perform operations in parallel.

Another object of the invention is a device, in particular a control device or an internal combustion engine, which are adapted to carry out a method in one of the advantageous embodiments described above.

A computer program with program code for carrying out all the steps of such a method when the program is executed in a computer forms a further subject of the invention.

Brief description of the drawings

Hereinafter, an embodiment of the present invention will be explained in more detail with reference to the accompanying drawings. Showing:

1 shows a sketch of an internal combustion engine in which a method according to the invention can be carried out;

FIG. 2 is a schematic illustration of the flow of operations during a starting operation of the internal combustion engine of FIG. 1; FIG. and

FIG. 3 shows a schematic representation of the sequence of operations during a starting process according to the invention of the internal combustion engine of FIG. 1.

Embodiment of the invention

1 schematically shows an internal combustion engine 10. It comprises an engine block with a plurality of cylinders 12, of which only one is shown in FIG. In the cylinder 12, a combustion chamber 14 is present, which is partially limited by a piston 16. This is connected via a connecting rod 18 with a crankshaft 20. On the crankshaft 20, in turn, a gear 22 is fixed. This carries on its circumference a total of 58 teeth (without reference numerals). There are no teeth over a perimeter extension corresponding to two teeth. The gap 24 thus formed on the circumference of the gear 22 is detected by an inductive sensor 26. The inductive sensor 26 is arranged adjacent to the toothed wheel 22 and is designed so that it can detect the passage 24 of the gap 24 when the toothed wheel 22 rotates. The gap 24 may also be referred to as an angle mark 24, as it indicates a certain angular position of the crankshaft 20.

Combustion air is supplied to the combustion chamber 14 through an inlet pipe 28 and an inlet valve 30. The combustion exhaust gases are discharged from the combustion chamber 14 via an exhaust valve 32 and an exhaust pipe 34. A throttle valve 36 allows the adjustment of the amount of air that passes through the inlet pipe 28 into the combustion chamber 14. The movement of the throttle valve 36 is performed by a servo motor 38. The reaching into the combustion chamber 14 air quantity is measured by a hot film sensor 40 ("HFM sensor"). In the exhaust pipe 38, a catalyst 42 is disposed, and the mixture composition of the exhaust gas is from a

Lambda probe 44 detected.

Fuel is supplied to the combustion chamber 14 from a fuel system 46 shown only symbolically in FIG. 1. Such a fuel system 46 may include a fuel tank, an electric prefeed pump, and a main mechanical pump. Furthermore, this includes

Fuel system 46 a referred to as "rail" or high-pressure accumulator fuel rail in which the fuel is stored under high pressure. To this an injection valve 48 is connected, which injects the fuel directly into the combustion chamber 14 of the internal combustion engine 10. The ignition of the present in the combustion chamber 14 air-fuel mixture is effected by a spark plug 50, which is supplied by an ignition system 52 with the required energy. A knock sensor 54 attached to the cylinder 12 of the internal combustion engine 10 detects a knocking combustion possibly taking place in the combustion chamber 14.

The operation of the internal combustion engine 10 is controlled by a control device 56. This is the output side connected to the ignition system 52, the injection valve 48, and the servo motor 38 of the throttle valve 36, and the input side, the controller 56 with the knock sensor 54, the lambda sensor 44, the inductive sensor 26 and the HFM sensor 40 is connected. As is apparent from Fig. 1, the fuel is injected into the combustion chamber 14 directly from the injection valve 48. The internal combustion engine 10 can be operated in different operating modes, depending on, for example, speed and torque. For example, it is possible to inject fuel into the combustion chamber 14 during the intake stroke, that is to say during a period in which the intake valve 30 is open. In this case, the fuel together with the air in the combustion chamber 14 forms a substantially homogeneous fuel-air mixture. Such injection is referred to as "homogeneous injection", the corresponding mode as "homogeneous".

However, it is also possible to inject the fuel during the compression phase, ie when the inlet valve 30 and the outlet valve 32 are closed, shortly before reaching the top dead center of the piston 16. Due to the special design of the injection valve 48, an ignitable fuel layer is present in this case only in the immediate vicinity of the spark plug 50, whereas in the remaining combustion chamber 14 of the cylinder 12 there is little or no fuel at all. Such an injection is referred to as "stratified injection", the corresponding mode as "layer". Also possible are any combinations of the two operating modes.

The necessary in an operating mode operations, calculations and the generation of corresponding control signals are processed by a controller 56 within a processing grid. There are time-synchronous processing grids in which certain operations are performed at certain constant time intervals. Other operations are performed in a processing grid synchronous with the rotational angle of the crankshaft 20. These other operations are also referred to herein as parameter calculations.

The current angular position of the crankshaft 20 is detected by the inductive sensor 26 via the detection of the gap 24 and the detection of the following teeth on the gear 22. Instead of an inductive sensor, for example, a Hall sensor could be used. The angular position of the crankshaft 20 is thus known to the control device 56. It is usually in "degree before top dead center ignition" (vZOT) of the piston 16. The intake valve 30 and the exhaust valve 32 are mechanically rigidly connected to the crankshaft 20 via the camshaft (not shown). In addition, also variably controllable valves from the prior art are known. The gap 24 on the gear 22 defines the beginning of a first and a second, to the rotation angle of the crankshaft 20 synchronous processing grid. These are referred to in Figs. 2 and 3 as "SYNCHROI" and "SYNCHRO2".

FIG. 2 schematically shows the sequence of a conventional high-pressure start. FIG. 2 refers to the internal combustion engine shown in FIG. 1 and describes an operating method for this internal combustion engine. During high-pressure startup, required operating variables are processed in operations. These are the first operation 61 and the second operation 62, which are exemplified herein. in the

Operation can be performed more than just these two operations 61 and 62. In operation 61, a parameter calculation is performed, wherein the filling of the combustion chamber is calculated. The operation 61 is clocked by "SYNCHRO1." In the operation 62 clocked by "SYNCHRO2", the fuel amount for a stratified injection, the ignition angle and the ignition energy are calculated. For details, refer to the above mentioned European application.

When the internal combustion engine is started, a start request 65 is first detected by the control device. Subsequently, the control device waits until a synchronization is present, that is to say when the engine is started. H. until the gap 24 is first detected on the gear. This time span will be in the

2 with the reference numeral 66 designates. Further, the reference numeral 67 designates a time period which designates a period of time from another start request at another rest position of the internal combustion engine.

After synchronization, it is determined in which combustion chamber the first combustion should take place. Subsequently, during a period of time 68, the above-mentioned operations 61 and 62 are carried out for this combustion chamber. At the end of the period 68, the ignition 70 takes place. In this case, the first fired combustion chamber is generally not the combustion chamber, which after switching off the engine, d. H. in the rest position, in the compression stroke, but another. This usually requires a longer startup time compared to the inventive method described below.

FIG. 3 shows the sequence of a method according to the invention. The same reference numerals denote the same processes as in FIG. 2. One of the differences compared to the method of Figure 2 is that during a startup process, a stored or otherwise determined rest position of the internal combustion engine is used. The rest position denotes the angular position of the crankshaft before the start of towing. A storage can take place, for example, by storing the rest position in a memory of the control device during a previous run-out of the internal combustion engine and retrieving it before or during a subsequent start-up procedure.

In the method according to the invention, a determination of the first combustion chamber to be fired takes place spontaneously on a start request 65. It is determined which of the combustion chambers is in a compression stroke and a sufficient air charge for a suitable

Combustion has. Subsequently, a spontaneous triggering of the operations 61 and 62 takes place, which are carried out consecutively, since the operation 62 requires results of the operation 61. It should be emphasized that the execution of the operation 61 neither waits for synchronization, nor does the execution of the operation 61 be bound to a specific angular position. It is assumed that the computational capacity and computational speed are sufficiently high to be able to execute the compressions clocking operations 61 and 62. It should also be noted that during towing the engine speed is low, so that the sweeping of an angular segment by the crankshaft lasts comparatively longer than at a normal or high speed of the internal combustion engine. Therefore, when towed, there is sufficient time not to have to follow the usual procedure when performing the operations 61 and 62.

Subsequently, a first ignition 70 takes place at the ignition angle position calculated therefor. The elapsed time since the start request to the first ignition time is denoted by 71. It can be clearly seen that a faster high-pressure start is possible with the method according to the invention than with the conventional method.

It is possible to carry out the method according to the invention also for the second or third or further combustion chambers to be fired, although a normal course of the operations necessary for this can already be possible with these combustion chambers. If the subsequent tooth gap 24 is swept over, then again a usual synchronization takes place and, with sufficient flow for a combustion chamber to be subsequently fired, a change to an embodiment of the operations 61 and 62 to the usual angular positions of Normal operation. Regarding the synchronization, it should be noted that this merely serves to check, since in the case of a stored rest position of the crankshaft of the internal combustion engine no renewed synchronization is necessary, since the control device is already synchronized from the beginning.

Claims

claims

A method for operating an internal combustion engine (10), wherein during operation of the internal combustion engine (10) in a normal operation, an operation for combustion of

Fuel in a combustion chamber (14) of the internal combustion engine (10) periodically at a fixed angular position of a crankshaft (20) of the internal combustion engine (10) is performed, characterized in that during a starting operation of the internal combustion engine (10), the operation (61, 62) independently is performed by the fixed angular position.

2. The method according to claim 1, characterized in that a known parking position of the internal combustion engine (10) is used to determine a first to be fired during the starting process combustion chamber (14), wherein the operation (61, 62) for combustion in the combustion chamber (14) to be fired first is carried out independently of the fixed angular position.

3. The method according to claim 2, characterized in that the first to be fired combustion chamber (14) is selected from a plurality of combustion chambers in dependence on the parking position of the internal combustion engine (10).

4. The method according to claim 2 or 3, characterized in that is selected as the first to be fired combustion chamber (14) of a plurality of combustion chambers, which in the parking position of the internal combustion engine (10) has sufficient charge for a first combustion in the starting process.

5. The method according to any one of claims 2 to 4, characterized in that the first to be fired combustion chamber (14) before the start of the starting process of the internal combustion engine (10) is determined.

6. The method according to any one of the preceding claims, characterized in that the

Operation (61, 62) is performed regardless of whether a synchronization of a control device (56) by detecting an angle mark (24) of the crankshaft (20) has already occurred.

7. The method according to any one of the preceding claims, characterized in that in the operation (61, 62) a parameter for the combustion of fuel in the combustion chamber (14) is calculated, wherein the parameter is an air filling amount of the combustion chamber (14), is an amount of fuel for the combustion chamber (14), an ignition angle and / or an ignition energy.

8. The method according to any one of the preceding claims, characterized in that in a normal operation a plurality of operations (61, 62) for a combustion of fuel in a combustion chamber (14) of the internal combustion engine (10) are made periodically at different, fixed angular positions, wherein during the starting process, at least two of the operations (61, 62) are carried out independently of the respectively determined angular positions.

9. Device, in particular control device (56) or internal combustion engine (10), which are adapted to carry out a method according to one of claims 1 to 8.

A computer program with program code for performing all the steps according to one of claims 1 to 8, when the program is executed in a computer.