DE102005058445B3 - Fuel amount reporting process for internal combustion engine cylinder involves detecting setting or movement signals at least when engine is switched off - Google Patents

Abstract

Method for determining a fuel volume and / or a fuel quantity, which or in a cylinder (2) of an internal combustion engine (1), in particular a diesel engine, with a common rail injection system (3), the pressure line (13) and at least has an injection valve (14) connected to the pressure line (13), by means of which at least one injection valve (14) is injected, in which a predetermined injection signal for at least one injection is generated by the at least one injection valve (14) and to the at least one injection valve ( 14) is emitted, pressure signals are recorded which represent a pressure drop in the pressure line (13) during the injection, and a value for the injected fuel volume or the injected fuel mass is determined using the detected pressure signal.

Description

The The present invention relates to a method of detection one in a cylinder of an internal combustion engine, in particular a Diesel engine, with a common-rail injection system injected fuel amount and means of implementation of the procedure

at Internal combustion engines, in particular internal combustion engines, is at Using a direct injection of the fuel to be burned injected directly into the combustion chamber. A frequently used for this purpose Injection system is the common rail injection. In common-rail injection systems, a high-pressure pump brings the Fuel to a high pressure level. The pressurized fuel fills up Piping system or one or more pressure lines, the or the at engine operation constantly under pressure or stand. The injection of fuel in the combustion chamber is made by actuation of electrically connected injectors connected to the pressure line. The injection timing and the injection amount are by a Engine electronics controlled, the corresponding injection signals emits the injectors. Such common-rail injection systems can for example for petrol engines and in particular for Diesel engines are used.

at Diesel engines will increase the injection rate depending on the load point and environmental conditions set. In multiple injections into a cylinder during a Takts can even the amounts of each individual injection are very different chosen be. The size of each Among other things, the amount injected into a cylinder influences combustion history, emissions, torque development and noise of the motor. Of particular importance is the coordination of the injection quantities for the individual cylinder of an internal combustion engine to each other; for example it may be desired be while to inject the same amount of fuel into all the cylinders of one cycle, to one as possible to achieve quiet running of the internal combustion engine.

The Injection quantity is among other things by the opening time of the injection valve and determines the pressure in the pressure line. For generating the injection signals A map can be used that matches the required injection quantity Valve opening time and optionally linked to the pressure in the pressure line. This map is for the control of the injection valves of all cylinders of the internal combustion engine used.

manufacturing tolerances and wear of the injection system, In particular, the injectors, but lead to that for a given internal combustion engine the accuracy of the map is not as high as desirable is, or that the accuracy decreases over time. Especially can when using the determined by means of the map valve opening times actually achieved injection quantities at different cylinders or injection valves from each other and / or from the desired Injection quantities differ.

In US 5 176 122 A a method for determining a quantity of fuel according to the preamble of claim 1 is described.

In JP 08004577 AA a method is described in which a malfunction of a common rail injection system is detected, in which a drop in the rail pressure during an injection is compared with an estimated value.

In DE 103 57 158 A1 a common-rail injection system is described in which the injection duration is corrected in response to a drop in the rail pressure during an injection. For this purpose, a deviation of the rail pressure drop from a target value for the pressure drop is determined and used for correction. In this way, differences for the injection valves in the injection quantities for each injection can be compensated.

In DE 103 01 236 A1 a method for starting an internal combustion engine is described with common rail injection, in which before the start of the internal combustion engine with a stationary drive shaft, a pressure generating device of the common rail injection system is switched on. After the following pressure buildup when the drive shaft is stationary, an injection signal is generated and delivered.

In US 2004/0237938 A1 describes a common-rail injection system, in the after stopping the engine for pressure reduction a predetermined amount of fuel is injected to, in particular in the event of a malfunction of the rail pressure regulator - the rail pressure on one for the injection valve permissible Reduce operating pressure. Is based on a motion signal a crankshaft encoder detected a stoppage of the drive shaft, An injection signal is generated and delivered.

In DE 197 20 378 C2 a method for determining the opening time of an injection valve of a high-pressure accumulator injection system is described in which a map based on the einzuspitzenden fuel quantity and the static Pressure in the high-pressure accumulator an injection period is derived.

Around Differences in injection quantities between different cylinders, which are caused by the injectors, to take into account can the valve opening times determined using the map using one for a respective cylinder or a respective injection valve specific Correction map to be corrected.

Around desired It is therefore to achieve running characteristics of the internal combustion engine It is important that the characteristic map and the correction maps show the characteristics the injection system with good accuracy. Is to it desirable the actual Injection quantity at one actuation to be able to determine an injection valve.

Of the The present invention is therefore based on the object, a method for determining a in a cylinder of an internal combustion engine with a common-rail injection system injected amount of fuel provide and provide means for carrying out the method.

The Task is solved by a method having the features of claim 1 and in particular a method for determining a fuel volume and / or a Amount of fuel, the or in a cylinder of an internal combustion engine with a common-rail injection system, the at least one pressure line and at least one injection valve connected to the pressure line for the Cylinder, injected by means of the at least one injection valve in which a predetermined injection signal for at least one injection generated by the at least one injection valve and to the at least an injection valve is discharged, pressure signals are detected, representing a pressure drop in the pressure line during injection, and using the detected pressure signal, a value for the injected Fuel volume or the injected fuel mass determined becomes.

The Task will be solved further by a device having the features of claim 7 and in particular a device for determining a fuel volume and / or an amount of fuel, the or in a cylinder of an internal combustion engine is injected with a common rail injection system, wherein the Common rail injection system at least one pressure line, a Pressure sensor for detecting the pressure in the pressure line and at least a connected to the pressure line, controllable by the device Injection valve for the Cylinder, and wherein the device has an injection signal output for the delivery of injection signals to the at least one injection valve, and a pressure signal input for detecting a pressure signal of the pressure sensor, which represents a pressure in the pressure line includes, and to is designed to carry out the inventive method, and in particular a predetermined injection signal for at least one injection for that at least to generate an injection valve and via the injection signal output to output to the at least one injection valve, pressure signals to detect the pressure sensor, the one taking place during the injection Pressure drop play, and from the pressure signals a value for the injected Determine fuel volume or the injected fuel mass.

The Invention is for Internal combustion engines, more precisely internal combustion engines, provided at which fuel into the cylinder or cylinders of the internal combustion engine done by a common-rail injection system. The common rail injection system can in particular a pressure line, is kept under pressure in the fuel to be injected, and at least one electrically operable connected to the pressure line Have injection valve. The internal combustion engine can via a or preferably have a plurality of cylinders, for each of which an injection valve or more injection valves are provided. As an internal combustion engine In particular diesel engines are currently considered, the invention is suitable but also for any other engines, especially those with direct injection of the fuel into the cylinder or cylinders.

One The idea underlying the invention is to determine the fuel volume and / or the amount of fuel, or the in a cylinder of the internal combustion engine with a common rail injection system is injected, at least one injection by means of at least to make an injection valve and thereby taking place pressure drop to capture in the pressure line. From the pressure drop can then on the injected fuel volume or the injected fuel quantity getting closed. The invention is therefore preferably for common rail injection systems can be used where possible Pressure or volume losses due to leakage are so low that they on the determination of the fuel volume or the amount of fuel from the pressure drop have no significant influence, or where the Influence of Leaks can be taken into account by appropriate corrections.

For the injection, a predetermined injection signal is generated and delivered to the at least one predetermined injection valve. The injection signal, which can in particular determine the duration of the opening of the injection valve can, for example wise according to a predetermined opening time or according to a desired injection quantity at a given pressure in the pressure line, for example, using an assumed only relation between pressure, valve opening time and injection quantity can be selected.

The predetermined injection signal can be used for all injectors Common Rail injection system to be dispensed simultaneously. Preferably However, an injection signal is cylinder by cylinder to the injection valve a given cylinder or, in the case of several injection valves per cylinder, the injection valves of the given cylinder delivered, which has the advantage that differences in injection between different cylinders can be detected. Particularly preferably, the Determining the fuel injection volume or the fuel injection quantity however for individual injection valves.

to Detection of the pressure drop associated with the injection in the pressure line is preferably the pressure before and after the Injection detected, a time course of pressure during the Injection on the other hand does not need to be done. These are pressure signals a pressure sensor detects the pressure in the pressure line of the Play common-rail injection system.

On the base of the pressure signals can then be the pressure drop and out of this the injected fuel volume and / or the injected fuel quantity be determined, the injection signal or by the injection signal certain opening time assigned.

to execution of the method, the device according to the invention is suitable for receiving the pressure signals of the pressure sensor, a corresponding pressure signal input and for delivering the injection signals, a corresponding injection signal output having. Furthermore, the device for carrying out the Method, in particular for generating the injection signals and Processing of the pressure signals formed.

At least when the internal combustion engine is switched off, position or movement signals are detected, from which a movement state of the drive shaft can be determined, Based on the position or motion signals is checked whether the Drive shaft is, and then the at least one injection signal generated and delivered. The device is. preferably further so educated and the computer program includes such instructions that the device or the processor when executing the instructions at least when switching off the engine position or motion signals detected, from which a state of motion of the drive shaft can be determined is, based on the position or motion signals checks whether the Drive shaft is, and then the at least one injection signal generates and delivers.

This has the advantage that the determination of the fuel injection amount or the fuel injection volume takes place when the internal combustion engine typically still has the normal operating temperature. Furthermore The pressure drop can be detected very accurately because no disturbing vibrations NEN occur through the operation of the internal combustion engine. This method is also suitable for Internal combustion engines in which a pressure generating device of Common rail injection system over the crankshaft is driven. For detecting the position or Movement signals, the device, in particular via a corresponding input. Preferably, the movement of the drive shaft from a sequence determined by position signals from a crankshaft sensor the internal combustion engine are discharged.

Basically the device corresponding non-programmable electrical circuits include. However, the device preferably comprises one with The processor connected to the injection signal output and the pressure signal input and a memory in which, among other things, a computer program is stored is that contains instruction in their execution the processor performs the procedure.

The invention therefore also relates to a computer program comprising instructions in the execution of which a data processing system carries out the method according to the invention, in particular instructions for determining a fuel volume and / or an amount of fuel which is in a cylinder of an internal combustion engine having a common-rail injection system, which has a pressure line and at least one associated with the pressure line injection valve for the cylinder is injected by means of at least one injector, wherein when executing the instructions by a processor of the data processing device generates a predetermined injection signal for at least one injection by the at least one injection valve and to the At least one injection valve is discharged, pressure signals are detected, which represent a pressure drop occurring in the injection in the pressure line, and using the detected pressure signal We rt is determined for the injected fuel volume or the injected fuel mass. The data processing device can in particular be a suitably designed device according to the invention. The data processing device can in particular by a entspre be given chenden part of the device according to the invention.

The Computer program further includes such instructions that the processor at execution the instructions at least when switching off the internal combustion engine Position or motion signals detected from which a state of motion of the Drive shaft can be determined, based on the position or movement signals verifies whether the drive shaft is stationary, and then the at least one injection signal generates and delivers.

Another The invention relates to a storage medium on which the computer program according to the invention is stored.

The Invention has the advantage that only by specifying the injection signals the corresponding fuel injection volumes or the corresponding Fuel injection quantities for each individual cylinder and in particular each individual injection valve can be determined. These are, except for the device no additional facilities in the Internal combustion engine and the common-rail injection system necessary since these already over have the injectors and the pressure sensor.

Preferably gets over it In addition, an already used for controlling the internal combustion engine Engine control unit by appropriate programming as a device for detection a fuel volume and / or a fuel quantity used. In this embodiment are so opposite an internal combustion engine with a common rail injection system kei ne Further facilities necessary, so that a particularly simple structure results. It is only necessary to program the engine control unit accordingly.

in principle the method can be used in any operating conditions of the internal combustion engine be determined in which the temporal pressure course except for Effect of the injection is known. A particularly accurate determination is possible with three different alternatives.

at In a first alternative method, it can be determined whether the Internal combustion engine according to at least a given stability criterion in is a stable operating condition, and the value for the injected Fuel volume or the injected fuel quantity is only determined if the stability criterion Fulfills is. The device is further designed for this purpose and the computer program includes such instruction that the device or the processor determines whether the internal combustion engine according to at least one predetermined stability criterion is in a stable operating condition, and the fuel volume value or the amount of fuel determined only if the at least one stability criterion Fulfills is. This embodiment has the advantage that an accurate detection of the pressure drop during the Operation of the internal combustion engine is possible. In particular, need then also the delivery of the injection signal and the detection of Pressure signals to be made only if the at least one stability criterion is satisfied. As injection can In this case, especially for the measurement intended injections or also normal, performed for the operation of the internal combustion engine injections be used. As a stability criterion can be used in particular that the fluctuation of a Load of the internal combustion engine reproducing parameter over a predetermined Time interval less than a specified fluctuation limit is. Alternatively or in addition can starting from during of operation detected pressure signals the maximum fluctuation of the Pressure in the pressure line over a predetermined time interval ermit determined and on the basis of the fluctuation be determined whether stable operating condition exists. So can for example, checked be whether the fluctuation of the pressure values is so low that they a sufficiently accurate detection of one on the injection allow expected pressure drop. For example, it can be checked whether the amount of pressure fluctuations is less than 20% of the expected caused by the injection pressure drop is. It is also possible, the change of a moving average of that during normal operation checked pressure signals reproduced pressure to check. there should the time interval over the moving average is made to be longer than the time period between three consecutive injections. The stability criterion is then fulfilled if the change the moving average is less than a predetermined threshold is. It is also possible, instead of just one stability criterion two or more stability criteria to check and perform the above steps only if all the stability criteria Fulfills are.

A second alternative method is considered when the generation of the pressure in the pressure line is not via the internal combustion engine, but by another pressure generating device. In this variant of the method, a pressure generating device of the common rail injection system is switched on before or at the start of the internal combustion engine when the drive shaft to establish a predetermined pressure in the pressure line, and then the injection signal is generated and discharged when the drive shaft is stationary. For this purpose, the device is preferably designed in this way, and the computer program preferably includes such instructions that the device or the processor is executed during execution of the Instructions before or at the start of the internal combustion engine with stationary drive shaft, a pressure generating device of the common rail injection system turns on to build up a predetermined pressure in the pressure line, and then generates and outputs the injection signal when the drive shaft is stationary. This variant offers the advantage that a determination of the fuel injection quantity or of the fuel injection volume can take place before the operation and the results can be used in the following operation. In addition, the pressure drop can be detected very accurately because no disturbing vibrations occur due to the operation of the internal combustion engine. In addition, in multiple implementation of the method at different times, the fuel volumes or quantities can be determined at different predetermined by the environment of the engine or its own temperature temperatures so that corrections of the injection can also be made depending on the temperature. In the case of an internal combustion engine, in particular of a gasoline or diesel engine, the drive shaft may in particular be the crankshaft. In particular, the pressure-generating device may comprise at least one fuel pump which can be switched on by the device by emitting a switch-on signal or can be put into operation by switching on the power supply. For this purpose, the device can in particular have a further output, via which the pressure generating device can be switched on.

at According to the method, it is preferred that a stop signal is detected, which represents a shutdown of the internal combustion engine, at least after closing the injectors pressure in the pressure line is built up, and after determining that the drive shaft is at least an injection signal is generated and delivered. This is the device preferably further developed and includes the computer program continue such instructions that the device or the processor at execution the instructions detects a stop signal, the shutdown of the Internal combustion engine reflects that at least after closing the Injectors pressure is built up in the pressure line, and after the statement that the drive shaft is the at least one Injection signal is generated and delivered. According to this embodiment is at a driven by the internal combustion engine fuel pump the still present at switching off the engine angular momentum used to build pressure in the pressure line by all injectors first be kept closed. In this case, preferably a flow regulator in the connection between the tank and the pressure generator by delivering corresponding flow control signals via a corresponding output set to maximum flow. Only after the resulting stoppage of the drive shaft and thus substantially constant pressure in the pressure line then becomes the injection which in this case represents only one injection, which does not serve but has similar characteristics can. This embodiment has the advantage that the necessary for carrying out the process Pressure in the pressure line very easy to set up without further aids can be. In an internal combustion engine with a not of the Drive shaft of the internal combustion engine driven pressure generating device is the pressure generating device preferably by generating and outputting respective control signals so controlled that the desired pressure built or an existing pressure is not degraded.

The second alternative methods and the method are particularly suitable to determine small injection quantities, not because of the injections caused pressure fluctuations only very low or absent are.

Preferably be the method and at least one of the first or second Alternative method combined, being in the phase in which the first Variant performed will, larger injection quantities be determined and before or after operation small quantities.

in principle needs only the fuel volume or the amount of fuel in the process for an injection valve to be determined. Preferably, the production and delivery the injection signal, the corresponding detection of the pressure signals and the determination of the fuel volume or the amount of fuel for each the cylinder, particularly preferred for each injector, in time performed in succession. For this purpose, the device may be designed accordingly and the Computer program may contain appropriate instructions. In order to can Values for all injectors are obtained.

The value for the fuel volume or the fuel quantity can be determined in different ways. For example, empirical or derived from theoretical considerations formulas can be evaluated. It is also possible to use neural networks. In the method, however, preferably the value for the fuel volume or the fuel mass is determined from the pressure signals using a characteristic map. For this purpose, the device is preferably designed further in this way and the computer program contains such instructions that it or the processor executing the instructions derive the value for the fuel volume or the fuel mass from the pressure signals using a characteristic map determined. This embodiment allows advantageously a particularly fast and accurate determination of the value for the fuel quantity or the fuel volume, since the map is easy and quick to read, the creation of the map, however, can be done with considerable time. Preferably, the map is stored for this purpose in the device, in particular a non-volatile memory of the device.

Of the Fuel can vary in temperature depending on the temperature exhibit. It is therefore preferred in the method that a temperature signal is detected, which represents a temperature of the fuel, and used in determining the amount of fuel. The device has this preferably over a temperature signal input and is further adapted to over the Temperature signal input to detect a temperature signal, the one Temperature of the fuel, and in determining the Fuel quantity to use. The computer program preferably has instructions, in their execution the processor detects a temperature signal indicative of a temperature of the Fuel and in determining the amount of fuel used. This embodiment has the advantage that even at varying temperatures of the fuel in the pressure line the value for the injected fuel volume or the injected fuel quantity can be determined exactly. In particular, the temperature of the fuel over the temperature dependence the density of the fuel and / or the modulus of elasticity or, the compressibility of the fuel. However, the temperature can only as independent Dimension can be used in the map.

Preferably is dependent on the method from the determined value of the amount of fuel control of Fuel injection adapted. The device is preferred for this purpose continue to be trained and the computer program contains such Instructions that the device or the processor executing the instructions dependent on from the determined value of the amount of fuel control of Fuel injection adapted. This embodiment offers the advantage that at each operating cycle of the internal combustion engine, the control the injection can be adapted and thus always a very accurate injection possible is. In particular, a cylinder or the injection valve associated map that the dependence of the valve opening time among other things of the desired Fuel injection amount or the desired fuel injection volume reproduces, be adapted. Alternatively, a correction map, that for the cylinder or injector specific correction of Map that dependency the valve opening time among other things of the desired Fuel injection amount or the desired fuel injection volume for all Cylinder reproduces the same, be adapted.

Especially Preferably, the adaptation is done for all Cylinder, allowing differences in injection behavior between at least approximately to the cylinders can be compensated.

at In a preferred embodiment injection signals for several Injections generated and delivered, where sys tematic, for example by Output of appropriate signals, at least two adjustable parameters, which have an influence on the injection quantity, in which for the normal Operation of the engine relevant range can be varied. In particular, instead of the valve opening time or in addition to this also varies the pressure in the pressure line of the common rail injection system become. The device is for this purpose preferably designed and the computer program preferably comprises such instructions, that injection signals for generates and releases multiple injections, systematically for example, by emitting corresponding signals, at least two adjustable parameters that influence the injection quantity, in the for the normal operation of the engine relevant range varies become. This has the advantage that achieved after adaptation of the controller can be that the common-rail injection system in the entire working pressure range exactly injects the desired amount. Especially preferred are all varies the injection quantity influencing adjustable parameters.

It but it is also possible to vary the pressure not systematically, but only in the implementation of the To capture the process and the determined fuel volume or attributed to the determined fuel quantity.

The Invention will be described in more detail below by way of example with reference to FIG Drawing explained. Show it:

1 a schematic representation of an internal combustion engine with a common rail injection system and an engine control unit according to a first preferred embodiment of the invention,

2 a schematic representation of a map for determining a in the internal combustion engine in 1 injected fuel quantity,

3 a schematic representation of a temperature dependence of a correction factor used in determining the amount of fuel injected,

4 a highly simplified flowchart of a method for determining an amount of injected fuel according to a first preferred embodiment of the invention,

5 a schematic representation of an internal combustion engine with a common rail injection system and an engine control unit according to a third example.

In 1 has an internal combustion engine 1 in the form of a diesel engine over four cylinders, which are constructed the same and in the usual way including the facilities provided for each of the cylinders. For the sake of simplicity, in 1 only one cylinder 2 and to those facilities provided, as used hereinafter in the description; the following description of the devices applies to the other cylinders accordingly. The cylinders are powered by a common rail injection system 3 fueled. An engine control unit 4 , which simultaneously constitutes an apparatus for determining fuel injection quantities according to a first preferred embodiment of the invention, controls the common-rail injection system 3 in response to signals from sensors on the internal combustion engine and the common rail injection system 3 ,

The internal combustion engine 1 has a drive shaft in the form of a crankshaft 5 , on the over connecting rods 6 the movement of the pistons 7 in the cylinders 2 is transmitted. A position sensor 8th detects the position of the crankshaft 5 and outputs corresponding position signals.

The common-rail injection system 3 has a supply line 9 from a fuel tank not shown in the figures, one in the supply line 9 arranged controllable flow regulator 10 (Such as a valve current regulator, also referred to as VCV) for controlling the flow of fuel through the supply line and one of the supply line 9 fed and from the drive shaft 5 driven high-pressure pump 11 , The high pressure pump 11 can the fuel through a very schematically shown pressure control valve 12 in one with the high pressure pump 11 connected pressure line 13 press.

To the pressure line 13 are electrically operated injectors 14 to injectors not shown separately in the figures in the cylinders 2 connected.

In or on the pressure line 13 are a pressure sensor 15 for detecting the fuel pressure in the pressure line 13 and a temperature sensor 16 for detecting the fuel temperature in the pressure line 13 arranged, the pressure or temperature signals generate.

The engine control unit 4 controls the internal combustion engine and in particular the common rail injection system 3 and determined by injections into the cylinders 2 injected fuel quantities.

It has a memory 17 , a processor 18 who is on the memory 17 accesses, as well as with the processor via corresponding not shown interfaces connected inputs and outputs.

A position signal input 19 of the engine control unit 4 is with the position sensor 8th connected and used to detect position signals of the position sensor 8th ,

A pressure signal input 20 and a temperature signal input 21 of the engine control unit 4 are with the pressure sensor 15 or the temperature sensor 16 connected and allow the detection of the sensors respectively issued pressure or temperature signals.

One with the flow regulator 10 connected flow controller control output 22 and one with the pressure control valve 12 connected pressure control valve control output 23 of the engine control unit 4 are used to output flow controller control signals or pressure control valve control signals to the flow controller 10 or the pressure control valve 12 ,

The engine control 4 finally has injection signal outputs 24 for the delivery of injection signals to the injection valves 14 ,

In a non-volatile part of the store 17 FIG. 10 is a computer program with instructions for carrying out the method of determining in-cylinder described below 2 injected fuel quantities, a TI map 25 and an injection quantity map explained in more detail below 26 saved. The computer program also contains instructions for controlling the common-rail injection system 3 , in particular the injection valves 14 and the pressure regulating valve 12 , This will be the TI map 25 , for a desired amount of fuel to be injected in dependence on the pressure in the pressure line 13 indicates corresponding valve opening times of the injection valves or data via corresponding injection signals, and in 1 only in conjunction with the TI map illustrated, the individual injectors associated correction maps for cylinder or injector specific correction of the values of the TI map used.

In normal operation, the engine control unit generates 4 by means of the processor 18 and the TI map 25 according to a given load or a predetermined torque with known methods injection signals for short-term opening of the injectors 14 by first of the torque or the load desired injection quantities and taking into account the prevailing pressure in the pressure line 13 by means of the TI map 25 Valve opening times for all injectors are determined. The valve opening times are then corrected injection valve specific using the correction maps associated with the individual injectors. The corrected valve opening times then serve to generate the injection signals.

to Determining quantities of fuel injected during an injection and a subsequent adaptation of the control of the internal combustion engine, In particular, the correction maps, the following method a first preferred embodiment carried out the invention what the computer program has appropriate instructions for.

Among other things, the method is based on the following consideration: In the case of an injection in a common-rail injection system, the pressure in the pressure line briefly drops in accordance with the injection quantity before it rises again to a preset value. From the pressure difference between the pressure before and after an injection and the pressure before the injection, the injection quantity can be determined. For example, an injection quantity map can be used 26 used as it is in 2 is exemplified, in the p the pressure in the pressure line 13 , Δp is the pressure difference and m is the amount of fuel injected. The physical basis of such a map is that the injected fuel volume .DELTA.V is related to the pressure loss and the pressure difference .DELTA.p. In the simplest case, a relationship between ΔV and Δp may be given, for example, by the following equation, where E is the modulus of elasticity of the fuel and V is the total hydraulic volume in the high pressure region, substantially the pressure line 13 describe: ΔV = V · Δp / E.

Under Using the known density of the fuel can then be a value for the injected fuel quantity can be determined.

A more detailed description of the relationship can be determined, for example, by an analytically or empirically determined function or a corresponding injection quantity characteristic map which is qualitatively defined in FIG 2 is shown, in the m denotes the injected amount of fuel.

To correct the temperature dependence of the modulus of elasticity or the compressibility E and the density of the fuel, the value for the injected fuel quantity m determined from the characteristic map can still be multiplied by a correction factor k dependent on the fuel temperature. A corresponding relationship between the correction factor and the fuel temperature T is qualitatively in 3 and can also be obtained quantitatively from analytical models or empirically.

at the method is at least a predetermined injection by the at least one injection valve made and thereby doing a pressure drop detected in the pressure line. In injection, it can, depending on the embodiment, a special for the measurement predetermined test injection or, during measurement during the Operation, also a normal injection for the operation of the internal combustion engine act by the appropriate injection signal and the conditions can be given in injection system. Using the detected pressure drop then becomes the injected fuel mass or quantity determined.

The procedure requires in each case that in the pressure line 13 a quasi-stationary pressure prevails, ie a pressure which is substantially constant except for the change by the injections, since otherwise the pressure drop due to the injection is superimposed by a change in pressure based on other causes and does not reflect the injection quantity correctly.

In the method according to the first preferred embodiment, the stable operating conditions or the quasi-stationary pressure are ensured by the fact that when switching off the internal combustion engine in the pressure line 13 a predetermined pressure is built up, and then with stationary drive shaft 5 the injection through the at least one injection valve 14 is carried out.

The steps of the procedure are in 4 roughly shown schematically.

In step S10, a stop signal is first detected that the internal combustion engine, ie in this case the diesel engine, should be switched off. There are then no further injection signals to the injection valves 14 delivered so that they are kept closed. As a result, no more fuel gets into the cylinder 2 , so that the internal combustion engine, more precisely, the drive shaft 5 , braked by the friction losses slowly comes to a standstill.

To ensure the highest possible pressure in the pressure line 13 build up, gives the Motorsteuerge guesses, more precisely, the processor 18 in step S12 via the outputs 22 and 23 Pressure control valve control signals or flow control valve signals to the pressure control valve 12 close and the flow regulator 10 to open. This will, except for leakage, a high pressure in the pressure line 13 built up to the drive shaft 5 has come to a standstill.

Next covered the engine control unit 4 in step S14 position signals of the position sensor 8th and check if the drive shaft 5 has come to a standstill. If this is not the case, it continues to record position signals.

Is detected during the test that the drive shaft 5 has come to a standstill, in step S16 first by detecting a pressure signal of the pressure sensor 15 the pressure in the pressure line 13 and by detecting a temperature signal of the temperature sensor 16 the temperature of the fuel in the pressure line 13 determined.

In step S18, then, for the injection, a predetermined injection signal, which is to correspond to a predetermined desired amount of fuel, from the engine control unit 4 or the processor 18 generated and via the injection signal output 24 to a given injection valve of the injectors 14 issued. It then takes place by opening the injector for a given by the injection signal valve opening time, the injection of fuel into the corresponding cylinder 2 ,

In the duration of the valve opening time after the delivery of the injection signal, then in step S20 again a pressure signal of the pressure sensor 15 via the pressure signal input 20 detects the pressure in the pressure line 13 after injection.

In Step S22 will then measure the pressure difference Δp between the before and after formed the injection detected pressure.

The processor determines from the determined pressure difference Δp 18 then using the injection quantity map 26 , ie in particular also the pressure in the pressure line 13 , and the correction factor determined using the detected temperature signal, the amount of fuel actually injected.

In step S24 is adapted to adapt the control of the fuel injection, the injection valve associated correction map accordingly by the valve opening time used at the determined pressure in the Drucklei device 13 the quotient of the desired and the determined fuel quantity is assigned.

Preferably Injections, i. the steps S16 to S24 for all injectors the internal combustion engine individually and for various desired fuel quantities or valve opening times carried out, to be able to adapt all the correction maps. This can be differences between compensated for the injection behavior of the various injectors so that a very smooth running of the engine can be achieved can.

In a preferred variant, injection signals for a plurality of injections are generated and delivered, wherein systematically, for example by emitting corresponding signals, at least two adjustable parameters which influence the injection quantity are varied in the range relevant to normal operation of the internal combustion engine. In particular, in addition to the valve opening time and the pressure in the pressure line 13 the common-rail injection system 3 varies by providing appropriate control signals to the pressure control valve 12 be issued. The engine control 4 has a correspondingly modified computer program.

It can then different value ranges of the correction maps adapted using, where appropriate, interpolation methods can.

A second example differs from the first embodiment in that during operation of the internal combustion engine operating phases are determined with quasi-stationary conditions and the injection quantities are determined in these phases. For this purpose, only the engine control unit, which at the same time constitutes a device for determining fuel injection quantities according to a second preferred embodiment of the invention, differs from that of the first exemplary embodiment, whereby in this case also only the programming of the processor 15 , easy to adjust. Be the reference numbers and designs for the internal combustion engine, the common-rail injection system and the engine control except for their programming are therefore also valid here.

For this purpose, it is constantly checked whether the internal combustion engine 1 according to a stability criterion in a quasi-stationary operating condition and thus the pressure in the pressure line 13 are in a quasi-stationary state. The engine control unit detects this 4 current values of a parameter that reflects the load of the internal combustion engine. This parameter is used in the engine control unit anyway. As a stability criterion, a threshold criterion for the temporal fluctuation of the values of the parameter in a predetermined time interval before the time of the test is used. The last values of the parameter are displayed over the time interval vall, whose duration is longer than the time interval of several, in the example 10, normal injections detected. From the detected values, the maximum fluctuation of the values, for example the difference between maximum and minimum, is determined and compared with the expected pressure drop caused by the injection. If this is so large in comparison to the fluctuation that a determination of the pressure drop is sufficiently accurate despite the fluctuations, the presence of a quasi-stationary state is established. For example, it may be required that the ratio of maximum fluctuation and expected pressure drop is less than a predetermined value less than 1, for example 0.2 or 20%.

There are then the steps S16 to S24 of the method in the first embodiment for each injection valve 14 executed.

A third example differs from the first embodiment in that now instead of that of the internal combustion engine 1 driven high-pressure pump 11 one independent of the internal combustion engine 1 electrically driven controlled high-pressure pump 11 ' is used (see. 5 ).

In addition, the engine control unit differs 4 ' , which at the same time constitutes a device for determining fuel injection quantities according to a third preferred embodiment of the invention, from the engine control unit 4 of the first embodiment by a high-pressure pump signal output 27 , via the control signals to the high-pressure pump 11 ' for controlling the same, and by the programming of the engine control unit, so that a method according to a third preferred embodiment of the invention for determining fuel injection quantities can be performed. All other components are unchanged from the first embodiment, so that the same reference numerals are used for them and the comments on the first embodiment apply here as well.

In the method, upon detection of a start signal for the internal combustion engine 1 through the engine control 4 initially only the high pressure pump 11 ' by delivering corresponding signals via the high pressure pump signal output 27 put into operation to a predetermined pressure in the pressure line 13 build. These are also the flow controller 11 and the pressure control valve 13 controlled accordingly. Before actuation of a starter not shown in the figures and thus at a stationary drive shaft 5 Then, the steps S16 to S24 of the first embodiment are performed.

The Methods of the first and third embodiments are suitable in particular for the determination of small injection quantities, since not by the Injections caused pressure fluctuations only very slightly or are not available.

In a particularly preferred fourth embodiment of the invention the method of the second embodiment while of the operation for measuring large Injection quantities and then the method of the first embodiment of the Measurement of small injection quantities carried out. This becomes a determination the injection quantities over a wide range of areas and a correspondingly extensive adaptation the engine control or the correction maps allows.

In a fifth For example, the method of the third embodiment becomes smaller for measurement Injection quantities before operation and then during operation the procedure of the second embodiment for measuring large Injection quantities performed. Also with this is a determination of the injection quantities over a wide volume range and a correspondingly extensive adaptation the engine control or the correction maps allows.

Further differentiate preferred embodiments From the embodiments described above is that for each Cylinder or its injectors or for each injector own TI map is provided, that for the respective injectors contains specific values. The correction maps can then omitted. The method now uses the correction maps, but the TI maps adapted so that differences in injection characteristics be balanced between the cylinders or injectors.

Claims (14)

Method for determining a volume of fuel and / or a quantity of fuel that is injected into a cylinder ( 2 ) an internal combustion engine ( 1 ) with a common-rail injection system ( 3 ), the at least one pressure line ( 13 ) and at least one with the pressure line ( 13 ) connected injection valve ( 14 ) for the cylinder ( 2 ), by means of the at least one injection valve ( 14 ) is injected, in which a predetermined injection signal for at least one injection by the at least one injection valve ( 14 ) and to the at least one injection valve ( 14 ), pressure signals are detected which have a pressure drop in the pressure line ( 13 ), and using the detected pressure signals, a value for the injected fuel volume or the injected amount of fuel determined is characterized in that at least when switching off the internal combustion engine ( 1 Position or motion signals are detected from which a movement state of the drive shaft ( 5 ) can be determined, is examined in the basis of the position or movement signals, whether the drive shaft ( 5 ), and in which thereafter the at least one injection signal is generated and delivered. Method according to claim 1, in which a stop signal is detected, which is a shutdown of the internal combustion engine ( 1 ), at least after closing of the injectors ( 14 ) Pressure in the pressure line ( 13 ), and after determining that the drive shaft ( 5 ), which generates and delivers at least one injection signal. Method according to one of the preceding claims, wherein the value for the fuel volume or the fuel quantity from the pressure signals using a characteristic map ( 25 ) be determined. Method according to one of the preceding claims, in a temperature signal is detected, which is a temperature of the fuel and used in determining the amount of fuel becomes. Method according to one of the preceding claims, in which injection signals for a plurality of injections are generated and delivered, wherein systematically at least two adjustable parameters which have an influence on the injection quantity, in which for the normal operation of the internal combustion engine ( 1 ) relevant range can be varied. Method according to one of the preceding claims, in in dependence from the determined value of the fuel amount, a control of the fuel injection is adapted. Device for determining a volume of fuel and / or a quantity of fuel which is injected into a cylinder ( 2 ) an internal combustion engine ( 1 ) with a common-rail injection system ( 3 ), wherein the common-rail injection system ( 3 ) at least one pressure line ( 13 ), a pressure sensor ( 15 ) for detecting the pressure in the pressure line ( 13 ) and at least one with the pressure line ( 13 ), can be controlled by the device injector ( 14 ) for the cylinder ( 2 ), and wherein the device has an injection signal output ( 24 ) for the delivery of injection signals to the at least one injection valve ( 14 ), and a pressure signal input ( 20 ) for receiving at least one pressure signal of the pressure sensor ( 15 ), and is configured to carry out the method according to one of claims 1 to 6, and in particular a predetermined injection signal for at least one injection for the at least one injection valve ( 14 ) and via the injection signal output to the at least one injection valve ( 14 ), pressure signals of the pressure sensor ( 15 ), which represent a pressure drop occurring during the injection, and to determine from the pressure signals a value for the injected fuel volume or the injected fuel quantity, characterized in that the device at least when switching off the internal combustion engine ( 1 ) Detects position or movement signals from which a movement state of the drive shaft ( 5 ) can be determined, based on the position or movement signals checks whether the drive shaft ( 5 ), and thereafter generates and outputs the at least one injection signal. Apparatus according to claim 7, which detects a stop signal which is a shutdown of the internal combustion engine ( 1 ) reflects that at least after closing of the injectors ( 14 ) Pressure in the pressure line ( 13 ), and after determining that the drive shaft ( 5 ), which generates and delivers at least one injection signal. Device according to one of claims 7 or 8, which determines the value for the Fuel volume or the amount of fuel from the pressure signals determined using a map. Device according to one of claims 7 to 9, which via a temperature signal input ( 21 ) and is further adapted, via the temperature signal input ( 21 ) to detect a temperature signal representing a temperature of the fuel and to use in determining the amount of fuel. Apparatus according to any one of claims 7 to 10 which continues to do so is formed that depending on the determined value of the amount of fuel, a control of the fuel injection adapted. Apparatus according to any one of claims 7 to 11, further adapted to generate and deliver injection signals for a plurality of injections, systematically having at least two adjustable parameters influencing the injection quantity; in which for the normal operation of the internal combustion engine ( 1 ) relevant range can be varied. Computer program comprising instructions in the execution of which a data processing system ( 4 ) performs the method according to one of claims 1 to 6, in particular instructions for determining a fuel volume and / or an amount of fuel that in a cylinder ( 2 ) an internal combustion engine ( 1 ) with a Com mon-rail injection system ( 3 ), which is a pressure line ( 13 ) and at least one with the pressure line ( 13 ) connected injection valve ( 14 ), by means of the at least one injection valve ( 14 ), wherein when the instructions are executed by a processor ( 18 ) of the data processing device ( 4 ) a predetermined injection signal for at least one injection by the at least one injection valve ( 14 ) and to the at least one injection valve ( 14 ), pressure signals are detected which have a pressure drop in the pressure line ( 13 ), and using the detected pressure signal, a value for the injected fuel volume or the injected fuel quantity is determined, at least when switching off the internal combustion engine ( 1 Position or motion signals are detected from which a movement state of the drive shaft ( 5 ) is determined, is checked by means of the position or movement signals, whether the drive shaft ( 5 ), and then the at least one injection signal is generated and delivered. Storage medium with a computer program stored thereon according to claim 13.