DE102012222097A1 - Method for operating fuel injection valve for internal combustion engine e.g. diesel engine, involves injecting fuel into chamber, where value characterizing energy for controlling actuator is formed based on injection parameters - Google Patents

Abstract

The method involves injecting fuel with partial injections into a combustion chamber of an internal combustion engine (10) by using an actuator i.e. piezoelectric actuator. A value characterizing control energy for controlling the actuator is formed based on injection parameters e.g. duration of partial injections, type of partial injection or fuel pressure in a fuel storage. Dependency of the value to the injection parameters is stored in a table and/or in a database and/or in a characteristic curve in a controlling and/or regulating device (22) of the engine. Independent claims are also included for the following: (1) a controlling and/or regulating device (2) a computer program for executing a method for operating a fuel injection valve (3) a storage medium for storing a computer program for executing a method for operating a fuel injection valve.

Description

State of the art

The invention relates to a method according to the preamble of claim 1, and a control and / or regulating device, a computer program and a storage medium according to the independent claims.

From the market known injection valves for internal combustion engines, which can be actuated by means of an electrically controllable actuator. For example, the actuator is designed as a piezo actuator ("piezo stack actuator"), which acts on a servo switching valve by means of a hydraulic coupler. The servo switching valve in turn causes an injection of fuel into an associated combustion chamber (cylinder) of the internal combustion engine. Depending on a control of the actuator, a respective amount of fuel is injected into the combustion chamber of the internal combustion engine.

A patent publication in this field is, for example, the EP 1 139 446 B1 ,

Disclosure of the invention

The problem underlying the invention is solved by a method according to claim 1, and by a control and / or regulating device, a computer program and a storage medium according to the independent claims. Advantageous developments are specified in subclaims. Features which are important for the invention can also be found in the following description and in the drawings, wherein the features, both alone and in different combinations, can be important for the invention, without being explicitly referred to again.

The invention has the advantage that an actuator for an injection valve of an internal combustion engine, in particular a piezoelectric actuator, can be controlled in such a way that an injection cycle can comprise a plurality of partial injections. Several injection parameters influencing the partial injections can be taken into consideration, whereby a driving energy of the piezoactuator is changed in a defined manner for each of the partial injections and thereby a quantity of fuel injected into a combustion chamber (cylinder) of the internal combustion engine can be measured comparatively accurately.

The invention relates to a method for operating a fuel injection valve for an internal combustion engine, in which the fuel is injected by means of an actuator with one or more partial injections. According to the invention, a variable characterizing a drive energy for the activation of the actuator for a partial injection depends on at least one injection parameter. Thus, the drive energy or the variable characterizing the drive energy can be optimally dimensioned as a function of the at least one injection parameter, and the injection of fuel can be correspondingly improved.

• – eine Anzahl der Teileinspritzungen;
• – eine individuelle Dauer der Teileinspritzungen;
• – eine Art der Teileinspritzung;
• – eine Bauart des Einspritzventils;
• – eine Bauart des Aktors;
• – ein Kraftstoffdruck in einem Kraftstoffspeicher;
• – eine Drehzahl der Brennkraftmaschine;
• – eine Alterung des Einspritzventils und/oder des Aktors;
• – eine Temperatur des Kraftstoffs und/oder des Einspritzventils und/oder des Aktors.

In one embodiment of the invention, the injection parameter is selected from the following group:

• A number of partial injections;
• An individual duration of the partial injections;
• A kind of partial injection;
• - a type of injection valve;
• A type of actuator;
• A fuel pressure in a fuel reservoir;
• - A speed of the internal combustion engine;
• - An aging of the injection valve and / or the actuator;
• - A temperature of the fuel and / or the injection valve and / or the actuator.

For example, there is a relationship between the number of partial injections and their individual duration and the actual amount of fuel injected in each case. This relationship can - among other things - depending on the design of the injector, the type of actuator and the fuel pressure in the fuel accumulator be non-linear and thus can not be described in a simple manner. Likewise, the speed of the internal combustion engine, the aging of the injection valve and / or the actuator and the said temperatures can have an influence on the respectively injected fuel quantity or on the required for a correct injection drive energy. The drive energy is changed according to the invention in dependence on the at least one injection parameter and the injection is thus optimized. There is a defined increase or adaptation of the drive energy for each of the partial injections, inter alia, as a function of partial injections chronologically preceding each other.

In a further embodiment of the invention, the actuator is a piezoelectric actuator. The actuation of the piezo actuator is different in comparison to a control of an example electromagnetic actuator. By means of the method according to the invention, it is also possible to actuate a piezoactuator in such a way that a defined quantity of fuel can be injected into the combustion chamber even if several partial injections are used per injection cycle.

According to a further embodiment it can be provided that the variable characterizing the drive energy is a drive voltage. Preferably, the piezo actuator can be controlled be specified by an amplitude and / or duration of the drive voltage. In particular, the amplitude of the drive voltage can be predetermined as a function of the number and / or the individual duration of the partial injections. This takes place, for example, in such a way that, taking into account the at least one injection parameter, the number and duration of partial injections preceding the same injection cycle is used to specify the control voltage required for a current partial injection or to correct it in the manner according to the invention.

Furthermore, it can be provided that the injection valve comprises a hydraulic coupler. Thus, the operation of the injector can be generally improved, which can be compensated according to the invention by the coupler specific tolerances and / or effects.

In addition, it can be provided that the group of the injection parameters, on which the variable which characterizes the activation duration, comprises a leakage of the hydraulic coupler. For example, the injection valve is designed as a servo valve, wherein the hydraulic coupler comprises an actuator-side piston and a servo-valve-operated piston on the piston side. Spatially between these two pistons a fuel-filled fluid space ("coupler gap") is arranged. When the actuator is actuated, the actuator-side piston transmits a force to the fluid space, as a result of which an increase in the hydraulic pressure takes place in the fluid space. As a result, in turn, the valve-side piston can be moved axially and the injection valve can thus be opened. As an undesirable consequence of the hydraulic pressure increase, leakage of fuel takes place from the coupler gap, whereby an axial distance between the two pistons is reduced. After closing the injection valve then an inflow of fuel takes place back into the coupler gap, after a certain time the original volume of the coupler gap is reached again. In particular, as a consequence of this leakage as well, the amount of fuel injected during a respective partial injection depends on the number and / or the duration of partial injections which may have previously taken place in the same injection cycle. The leakage causes, so to speak, a loss of stiffness of the hydraulic coupler, whereby - without the inventive method - transmitted via the actuator to the hydraulic coupler axial stroke and thereby generated in the coupler hydraulic pressure may not be sufficient to all the desired opening operations of the injector per injection cycle with the required precision. An indirect consideration of the leakage is possible, for example, via the above-mentioned consideration of the number of injections.

The implementation of the method can be improved if the dependence of the variable characterizing the drive energy on the injection parameter or on the injection parameters in a characteristic field and / or in a table and / or in a database and / or in a characteristic curve in a control and / or or control device of the internal combustion engine is stored. This allows a particularly simple and accurate control of the actuator. In particular, with a comparatively large number of injection parameters taken into account according to the method, a relationship defined thereby remains manageable.

Preferably, the method according to the invention is carried out using a control and / or regulating device for the internal combustion engine. This is done entirely or to arbitrary parts by means of a computer program which is stored on a suitable storage medium.

Hereinafter, exemplary embodiments of the invention will be explained with reference to the drawings. In the drawing show:

1 a simplified schematic of an internal combustion engine and a fuel system;

2 an embodiment of an injection valve for the internal combustion engine with a piezo actuator, a hydraulic coupler and a servo valve in a schematic sectional view;

3 a hydraulic coupler similar to the embodiment of the 2 in a schematic sectional view;

4 a first block diagram for a method for operating the injection valve;

5 a second block diagram for the method for operating the injection valve; and

6 a flowchart for the method for operating the injection valve.

The same reference numerals are used for functionally equivalent elements and sizes in all figures, even in different embodiments.

The 1 shows a simplified scheme of a fuel system 11 an internal combustion engine 10 with present four cylinders 12 ("Combustion chambers") and associated injectors 14 ("Fuel Injectors") for injecting fuel. The Injectors 14 can each by an electrical actuator 13 be operated. Above the injectors 14 is a high-pressure accumulator 16 (Fuel storage, "Rail") shown, from a high-pressure line 18 fueled by a pressure sensor 20 is monitored. The high-pressure accumulator 16 indicates a fuel pressure 17 on.

The internal combustion engine 10 is designed either as a gasoline engine or as a diesel engine. In the upper right part of the 1 is a control and / or regulating device 22 shown together with indicated outgoing and incoming control lines, and a data memory contained therein 24 (Storage medium), a computer program 26 and groups of maps 25 and 27 , Alternatively or in addition to the maps 25 and 27 may be the control and / or regulating device 22 also comprise a database and / or several tables and / or characteristic curves.

In operation, a fuel pump (not shown) feeds the high pressure accumulator 16 over the high pressure line 18 , wherein the pressure sensor 20 the current fuel pressure 17 via an indicated signal line to the control and / or regulating device 22 reports. The four injectors 14 set depending on a drive signal of the electric actuator 13 a certain amount of fuel into the cylinders 12 from.

2 shows one of the injectors 14 of the 1 in a schematic sectional view. The injection valve 14 includes a first housing part 28a and a second housing part 28b in an upper and middle or in a lower portion of the drawing of 2 , In an upper area of the drawing, the injection valve 14 a piezo actuator 30 on, which is designed as a piezo stack actuator. The piezo actuator 30 In this case, a preferred embodiment of the electrical actuator 13 of the 1 dar. The respective layers of the piezo actuator 30 are vertically stacked in the drawing. In the drawing left and right electrodes of the piezo actuator 30 are each in common via a first and a second electrical line 32 respectively. 34 connected.

In a middle to lower area of the drawing of 2 is a hydraulic coupler 36 arranged. An in the drawing lower end portion of the piezo actuator 30 is with an actuator-side piston 38 of the hydraulic coupler 36 operatively connected. Furthermore, the hydraulic coupler includes 36 a valve-side piston 40 , which in the drawing vertically below the actuator-side piston 38 is arranged. Vertically between the actuator-side piston 38 and the valve-side piston 40 is a coupler gap 42 arranged, which at the same time one with fuel 44 filled fluid space 55 forms.

An in the drawing lower end portion of the hydraulic coupler 36 is with a servo valve 48 axially coupled. A valve element 50 of the servo valve 48 is made by a valve spring designed as a helical spring 52 in the drawing up against a valve seat 54 or against an end portion 64 (please refer 3 ) of the valve-side piston 40 pressed.

Furthermore, the injection valve comprises 14 an inlet 53 through which fuel 44 can be supplied. For this purpose, the injection valve 14 several interconnected or connectable fluid spaces 55 on where the fuel is 44 according to the function of the injection valve 14 can flow.

In operation of the injector 14 gets through to the electrical wires 32 and 34 applied drive voltage 56 an axial length of the piezo actuator 30 changed. This is at the same time an electrical drive energy to the piezo actuator 30 transfer. Depending on the length of the piezo actuator 30 becomes the actuator-side piston 38 for example, moves down in the drawing. This increases a hydraulic pressure in the coupler gap 42 , which in turn forces the valve-side piston 40 is exercised. If this force is greater than one by the force of the valve spring 52 as well as by hydraulic pressures certain threshold value, the valve element 50 from the valve seat 54 lift off, creating a hydraulic pressure in a pressure chamber 59 decreases and the valve needle, not shown, opens. Thus, fuel can 44 be injected into the combustion chamber. This is done in particular by means of partial injections 57 which include, for example, a pilot injection, a main injection and a post-injection. After closing the injector 14 then takes place an inflow of fuel 44 back into the coupler gap 42 , wherein after a certain time the original volume of the coupler gap 42 is reached again.

3 shows the hydraulic coupler 36 in one to the 2 similar embodiment in a schematic sectional view. The hydraulic coupler 36 includes a substantially cylindrically shaped first and second wall element 58a and 58b , Radially within the second wall element 58b is a substantially rotationally symmetric coupler body 60 arranged. Radially inside the coupler body 60 are the actuator-side piston 38 and the valve-side piston 40 arranged. The actuator-side piston 38 has an upper end portion in the drawing 62 for axial coupling to the piezo actuator 30 on. The valve side piston 40 has the lower end portion in the drawing 64 for axial coupling to the valve element 50 of the servo valve 48 on.

Furthermore, the hydraulic coupler comprises 36 a (schematically shown) coil spring 66 (see also the 2 ), by means of which the valve-side piston 40 with comparatively little force in the drawing down against the valve element 50 is pressed. Another spring, by means of which the actuator-side piston 38 axially against a lower end portion in the drawing of the piezo actuator 30 (please refer 2 ) is pressed in the 3 not shown. The function of the hydraulic coupler 36 of the 3 corresponds to the already in the 2 described function. By radial gap, which functionally between the coupler body 60 and the actuator-side piston 38 or the valve-side piston 40 are formed takes place - depending on the respective hydraulic pressure conditions - a leak 67 from or into the coupler gap 42 ,

4 shows a first block diagram for a method for operating the injection valve 14 , A signal flow or an order of method steps takes place in the drawing essentially from left to right.

In a left-hand area in the drawing is a first group of maps 25 shown. The maps 25 presently have two input variables:
First, the fuel pressure 17 characterizing size 68 and second, an individual voltage requirement (so-called "ISA class") of the injector 14 characterizing size 70 , Furthermore, the maps have 25 in this case, a voltage value 72 as the starting point.

In a block 74 bottom left in the drawing of 4 gets out of a temperature 76 a correction value 78 determined. The temperature 76 is a fuel temperature or a temperature of the injection valve 14 or a temperature of the piezo actuator 30 , The correction value 78 is used to get out of the maps 25 determined voltage value 72 to a corrected voltage value 72a to correct.

In one in the drawing of 4 right area includes a dashed frame 80 symbolically a second group of maps 27 , The maps 27 have several input variables in the present case: the corrected voltage value 72a that the fuel pressure 17 characterizing size 68 that the individual voltage requirement of the injector 14 characterizing size 70 , at least one size 82 ("Type", injection type), which has a number and an individual duration of partial injections 57 characterized in the combustion chamber, a speed 84 the internal combustion engine 10 , as well as other sizes, which a type of injection valve 14 and the piezo actuator 30 and a respective aging of the injection valve 14 and / or the piezo actuator 30 characterize. This is in the 4 through an arrow 86 indicated.

The sizes 68 . 70 . 82 . 84 and 86 represent injection parameters, one of which is the driving energy of the piezo actuator 30 characterizing size - in the present case so the driving voltage 56 - Depends on or is made dependent on the method. Preferably - but by no means necessarily - include the injection parameters and a size, which directly the leakage 67 characterized. In addition, also for the maps 27 the temperature 76 be used as a parameter or as an additional input. This is because of the already taken account of the temperature 76 in the block 74 - but not mandatory and therefore in the 4 not shown. Due to the fact that in the block diagram of 4 "Groups" of maps 25 respectively. 27 a simple parameterization by means of one or more of said injection parameters is possible. Alternatively or additionally, it is possible to have higher-dimensional maps 25 respectively. 27 to use.

In the present case, the second group of maps 27 an output variable. This is the drive voltage 56 for controlling the piezo actuator 30 or one the drive voltage 56 characterizing size. Especially those with the frame 80 included elements of the 4 shown block diagram allow the very precise control of the piezo actuator 30 ,

That in the 4 The method shown operates as follows: Depending on the fuel pressure 17 , the size 70 and the correction value 78 in a first step, the corrected voltage value 72a determined. In a second step, the corrected voltage value 72a by means of the second group of maps 27 corrected again, using the sizes shown in the drawing and already described 68 . 70 . 82 . 84 and 86 ,

In this way, an amplitude and / or a duration of the drive voltage 56 specific to each of the part injections associated with an injection cycle 57 optimized preset. This is done such that one at each of the split injections 57 injected portion of the fuel 44 essentially only one by the control and / or regulating device 22 predetermined associated control period, but not on the number and duration of temporally preceding partial injections 57 depends.

As a result, a predetermined fuel quantity for a respective injection cycle can be injected into the combustion chamber in a defined manner, and the accuracy is essentially independent of the number and / or the individual duration of the partial injections 57 , In particular, the in the 3 illustrated leakage 67 , which depend on the number and duration of the partial injections 57 to a constantly different axial distance between the actuator-side piston 38 and the valve-side piston 40 can lead, by means of the maps 27 be optimally taken into account.

5 shows a second block diagram for carrying out the method. Regarding the 4 show the 5 an alternative embodiment for those in the frame 80 illustrated elements or sizes.

In a left area of the drawing of 5 is a functional block 88 arranged, which from the corrected voltage value 72a depending on the size 82 ("Type", injection type), which has a number and an individual duration of partial injections 57 characterized in the combustion chamber, a plurality of output variables 90a to 90z generates which groups of maps 27a to 27z be supplied as input variables. The maps 27a to 27z also show the size 68 , the size 70 , the speed 84 and the sizes 86 as common input variables or parameters. In one to the 4 In a similar way, driving voltages are generated 56a to 56z generated for each injection type. An Indian 5 not shown selector switch or multiplexer selects depending on the size 82 one of the drive voltages 56a to 56z and sets this as drive voltage 56 for the piezo actuator 30 ready.

The method according to the 5 can be carried out such that only for such activations of the piezo actuator 30 , which due to the leakage 67 a larger axial stroke of the piezo actuator 30 require a correction for the drive voltage 56 is carried out. This can optionally also an electrical power in the piezo actuator 30 or in the piezo actuator 30 driving facilities are reduced.

6 shows a flowchart for performing the method for operating the injection valve 14 , In a starting block 92 begins the procedure shown in the drawing. Below is in a block 94 using the sizes 68 and 70 as well as the temperature 76 a corrected voltage value 72a determined, comparable to the 4 ,

The following is the corrected voltage value 72a in a block 96 using the sizes 68 . 70 . 82 and 86 as well as the speed 84 by means of the maps 27 corrected again. This becomes the drive voltage 56 generated and for the piezo actuator 30 provided. This is also comparable to the 4 , In an endblock 98 ends in the 6 presented procedure.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 139446 B1 [0003]

Claims (10)

Method for operating a fuel injection valve ( 14 ) for an internal combustion engine ( 10 ), in which by means of an actuator of the fuel ( 44 ) with one or more partial injections ( 57 ), characterized in that a variable characterizing a drive energy for the activation of the actuator for a partial injection ( 57 ) of at least one injection parameter ( 68 . 70 . 82 . 84 . 86 ) depends. Method according to claim 1, characterized in that the injection parameter ( 68 . 70 . 82 . 84 . 86 ) is selected from the following group: a number of partial injections ( 57 ); An individual duration of the partial injections ( 57 ); - a kind of ( 82 ) of the partial injection ( 57 ); A type of injection valve ( 14 ); A type of actuator; A fuel pressure ( 17 ) in a fuel storage ( 16 ); A speed ( 84 ) of the internal combustion engine ( 10 ); An aging of the injection valve ( 14 ) and / or the actuator; A temperature ( 76 ) of the fuel ( 44 ) and / or the injection valve ( 14 ) and / or the actuator. Method according to one of claims 1 or 2, characterized in that the actuator is a piezoelectric actuator ( 30 ). Method according to one of the preceding claims, characterized in that the size characterizing the drive energy is a drive voltage ( 56 . 56a - 56z ). Method according to one of the preceding claims, characterized in that the injection valve ( 14 ) a hydraulic coupler ( 36 ). Method according to claim 5, characterized in that the group of injection parameters ( 68 . 70 . 82 . 84 . 86 ), of which the variable characterizing the activation duration depends, a leakage ( 67 ) of the hydraulic coupler ( 36 ). Method according to at least one of the preceding claims, characterized in that the dependence of the variable characterizing the drive energy on the injection parameter ( 68 . 70 . 82 . 84 . 86 ) or the injection parameters ( 68 . 70 . 82 . 84 . 86 ) in a map ( 25 . 27 ) and / or in a table and / or in a database and / or in a characteristic curve in a control and / or regulating device ( 22 ) of the internal combustion engine ( 10 ) is stored. Control and / or regulating device ( 22 ) for an internal combustion engine ( 10 ), characterized in that it is adapted to carry out a method according to one of claims 1 to 7. Computer program ( 26 ), characterized in that it is programmed to perform a method according to any one of claims 1 to 7. Storage medium ( 24 ), characterized in that a computer program ( 26 ) is stored according to claim 9.

Images