DE102011078844B4 - Method for injection of fuels with variable injection rate curves, fuel injection system and internal combustion engine - Google Patents

Abstract

Method for injecting pressurized fuels into an internal combustion engine by means of an injection valve, wherein during a combustion cycle the fuels are injected into the internal combustion engine via at least one valve opening operation of the injection valve, wherein at least one of the valve opening operations is configured n-phase with n ≥ 2, so that in a first phase, the injection valve is initially partially or fully opened and fuel injected at a first injection rate (r1), which is followed by at least one further phase, wherein during the at least one further phase, the injection valve each one of the preceding phase deviating opening position occupies, so that fuel is injected with a respectively deviating from the previous injection rate injection rate (r2, r3, ..., rn) and finally takes place closing the injector, wherein the course of the at least one of the n-phasi The total amount of fuel (m) injected in the whole n-phase valve opening process, - partial fuel quantities (m1, m2, m3, ..., mn), which during a respective phase of the - Duration of the respective phase (T1, T2, T3, ..., Tn) of the n-phase valve opening operation, which is specified by the respective opening position of the injection valve and the pressure of the fuel, - injection rate of the respective phase (r1, r2, r3, ..., rn) of the n-phase valve opening operation, which is specified via the respective opening position of the injection valve and the pressure of the fuel, characterized in that in the event that during the at least one n-phase valve opening operation in any phase a complete opening of the injector takes place, from the above-defined amount of all For mparameter 2n predetermined shape parameters and the remaining parameters are derived from the predetermined parameters, or for the case that during the at least one n-phase valve opening operation in p phases, with p <n, a complete opening of the injection valve, while the fuel with the maximum injection rate (rvh) is injected, from the above defined set of all shape parameters 2n - p given shape parameters and the remaining parameters are derived from the predetermined parameters and that ...

Description

The present invention relates to a method for injecting pressurized fuels into an internal combustion engine, wherein variable injection rate profiles are achieved by specifying specific shape parameters of the injection profile of a multi-phase valve opening process of the injector and the derivation of the further shape parameters from the given shape parameters. Furthermore, the invention relates to a fuel injection system, the program is set up such that it can be operated by the method according to the invention. In addition, the present invention relates to an internal combustion engine comprising a fuel injection system according to the invention.

Today's established injection systems with servo concept can either open or close the position of the injection needle. However, intermediate positions can not be held and needle positions can not be precisely controlled.

A new generation of injection systems with piezo drive and mechanically directly operated nozzle needle offers the possibility in principle of completely free needle position control respectively injection rate profile shaping. The variable Nadelteilhub and the needle seat throttling determine the flow, limited only by the flow coefficient of the nozzle.

From the document US 2005/0 252 494 A1 is known such a fuel injection system and a method for its control, with which a free injection rate history shaping can be made.

Also the documents US 2009/0 063 010 A1 and US 2009/0 063 016 A1 disclose injection control systems with corresponding injection valves, which allow continuously variable injection rates, in particular referred to as "boot shape", such injection being formed from two directly merging ice injection phases, with different injection rates.

Investigations have shown the advantages of injection rate progression in terms of fuel consumption, emissions (NOx, PM, HC, and CO), and stationary combustion noise for individual operating points. The rates were adjusted by hand by direct adjustment of the electrical control parameters. This procedure only works for inpatient examinations. The goal, however, is to operate an engine or a vehicle depending on the load and speed with rate progression formation.

The problem here is to make the new fundamental freedoms of rate progression usable by appropriate setpoint specifications and their control technology implementation.

The prior art is a set interface that describes the number of injections as well as each set and each position (angular position). Ie. each injection is defined by two parameters and allows injection patterns to be varied over quantities and injection breaks. In abstract terms, the injection rate pattern consists of a combination of trapeziums of fixed height and variable length and triangles of variable height (see 1a ).

With respect to such known from the prior art method is on 1 referenced, wherein 1a) represents a corresponding trapezoid fixed height; In this case, the injection duration is shown on the abscissa and the injection rate on the ordinate.

1b) shows the injector of a current injection, in which a driving time is calculated from a predetermined target amount and a predetermined rail pressure.

The necessary electrical activation duration for each injection is determined via the injector map or the so-called TI map as a function of the target quantity and fuel pressure. The rail pressure is approximately the same for all injections of a working cycle and must be understood as a given boundary condition of the quantity realization (see 1b ).

In addition, it is known from the prior art to carry out several injection processes per combustion cycle. A corresponding exemplary injection pattern according to the prior art is in 2 shown. The parameters determined at each injection are, for example, the start of injection (SOI) and the amount of fuel used per injection.

Based on this, it is an object of the present invention to provide a method for the injection of pressurized fuels, which allows a further refinement of the injection process. In addition, it is an object of the present invention to further optimize the combustion processes by the fuel injection, so that a further improvement of the combustion and / or a further reduction of the engine noise can be achieved. In addition, it is an object of the present invention to make advantageous use of the basic possibility with a manageable complexity and to make it accessible via a quantity interface of the application / application and thus also to realize a high rate flexibility with the lowest possible number of parameters and high volume stability. Further objects of the present invention are to provide a fuel injection system and an internal combustion engine with such a fuel injection system for carrying out the method according to the invention.

This object is achieved with respect to the method for injection with the features of claim 1, with respect to a fuel injection system with the features of claim 17 and with respect to an internal combustion engine with the features of claim 20. The respective dependent claims are advantageous developments.

According to the invention, a method for injecting pressurized fuels into an internal combustion engine by means of an injection valve is thus specified, in which the fuels are injected into the internal combustion engine via at least one valve opening operation of the injection valve during a combustion cycle.

In this case, at least one of the valve opening operations is n-phase with n ≥ 2, ie multi-phase, configured, wherein in a first phase, the injection valve is initially partially or fully opened and fuel at a first injection rate (r ₁ ) is injected, which is at least one further phase connects, wherein during the at least one further phase, the injection valve in each case assumes a deviating from the preceding phase opening position, so that fuel is injected at a deviating from the previous injection rate injection rate (r ₂ , r ₃ , ..., r _n ) and finally a closing of the injection valve takes place.

The injection rate is derived from the opening position of the valve and the prevailing pressure of the fuel.

• – Gesamtkraftstoffmenge (m), die beim gesamten n-phasigen Ventilöffnungsvorgang eingespritzt wird,
• – Teilkraftstoffmenge (m₁, m₂, m₃, ..., m_n), die während einer jeweiligen Phase des n-phasigen Ventilöffnungsvorgangs eingespritzt werden,
• – Dauer der jeweiligen Phase (T₁, T₂, T₃, ..., T_n) des n-phasigen Ventilöffnungsvorgangs, die über die jeweilige Öffnungsposition des Einspritzventils und über den Druck des Kraftstoffs vorgegeben wird,
• – Einspritzrate der jeweiligen Phase (r₁, r₂, r₃, ..., r_n) des n-phasigen Ventilöffnungsvorgangs, die über die jeweilige Öffnungsposition des Einspritzventils und über den Druck des Kraftstoffs vorgegeben wird,

Insgesamt resultieren somit allgemein 3n + 1 mögliche Formparameter, um das Einspritzprofil zu definieren. Gemäß der vorliegenden Erfindung umfasst daher ein einzelner n-phasiger Ventilöffnungsvorgang, d. h. der Zeitraum vom einmaligen Öffnen des Einspritzventils bis zum abschließenden Verschluss des Einspritzventils, mehrere Positionen, in denen das Ventil geöffnet ist. Bei einer partiellen Öffnung des Ventils wird dabei eine geringere Injektionsrate des Kraftstoffes erzielt, während bei einer vollen Öffnung die maximale Einspritzrate (r_vh) des Kraftstoffs erreicht wird. Die jeweilige Einspritzrate des Kraftstoffs ist dabei außer vom Öffnungszustand des Ventils noch vom Druck abhängig, der auf dem Kraftstoff anliegt. Dieser wird jedoch in der Regel nahezu konstant auf einem vorher eingestellten Wert gehalten.The injection profile, ie the time profile of the injection rate during the n-phase valve opening process or injection process is defined by the following shape parameters:

• Total fuel quantity (m) injected during the entire n-phase valve opening process,
• Partial fuel quantity (m ₁ , m ₂ , m ₃ ,..., M _n ) injected during a respective phase of the n-phase valve opening operation,
• Duration of the respective phase (T ₁ , T ₂ , T ₃ ,..., T _n ) of the n-phase valve opening process, which is predetermined via the respective opening position of the injection valve and via the pressure of the fuel,
• - Injection rate of the respective phase (r ₁ , r ₂ , r ₃ , ..., r _n ) of the n-phase valve opening operation, which is specified via the respective opening position of the injection valve and the pressure of the fuel,

Overall, therefore, generally 3n + 1 possible shape parameters result to define the injection profile. According to the present invention, therefore, a single n-phase valve opening operation, ie, the period from the one-time opening of the injection valve to the final closure of the injection valve, comprises a plurality of positions in which the valve is opened. In a partial opening of the valve while a lower injection rate of the fuel is achieved, while at a full opening, the maximum injection rate (r _vh ) of the fuel is achieved. The respective injection rate of the fuel is in addition to the opening state of the valve still dependent on the pressure applied to the fuel. However, this is usually kept almost constant at a preset value.

It is essential to the invention that in the event that a complete opening of the injection valve does not occur during the at least one n-phase valve opening operation, 2n mold parameters are predetermined from the above-defined set of all mold parameters and the remaining parameters are derived from the predetermined parameters, or the case that during the at least one n-phase valve opening operation in p phases, with p <n, a complete opening of the injection valve, while the fuel is injected at the maximum injection rate (r _vh ), from the above-defined amount of all shape parameters 2n - p form parameters are given and the remaining parameters are derived from the given parameters. The injector control is derived from the shape parameters and the specifications A target injection rate and a fuel pressure are converted into an energy characteristic value of the injector drive with a partial lift injector map.

In the method according to the invention, a final and complete definition of the injection profile can thus be carried out by specifying a limited number of shaping parameters. The form parameters to be selected or predetermined, ie m, m _n , r _n or T _n, can be different for each phase, but also the same. Furthermore, it is possible to specify the same or a different number of shape parameters for each phase, with the proviso that their total number meets the above-mentioned boundary conditions.

In the case that the multi-stage injection process takes place in the pure partial lift mode, 2n parameters must be specified in order to finally define the shape curve. Here, p = 0.

If during this multi-stage injection process at least one complete opening of the injection valve takes place (full stroke), only 2n-p shape parameters must be specified, where p is the number of full strokes during this process.

In the last variant, it is assumed that the injection rate during a full stroke, ie during a complete valve opening (r _vh ) to a first approximation is constant and thus not variable.

Individual phases can be defined via different pairs of form parameters, due to the fact that, with good approximation, the phase quantity is the product of phase duration and phase rate. For the parameter pair [phase quantity, phase duration], the rate of the respective phase is derived as an amount divided by duration. For [phase rate, phase duration] the respective phase quantity is derived as a rate multiplied by duration, and for [phase quantity, phase rate] the phase duration is derived as an amount divided by rate.

The invention enables a control of the injector and thus a precise adjustment of the amount of fuel that is required by the engine in each operating condition. The parameters can be stored, for example, in a controller, so that a control of the engine with a respective previously defined amount of fuel is possible, in the event that the respective parameters are realized.

The advantages that result from the injection according to the invention are proven emission advantages (NOx, PM, HC, CO), lower combustion noise due to cylinder pressure profile formation, lower jet penetration depths, for example to avoid oil dilution in the regeneration mode, and a significant reduction in injector noise. The pure partial lift injection, d. H. an injection in which at no time a full opening of the injector valve is achieved, is particularly quiet because the Absteuern from the partial stroke minimizes the closing noise and no upper stop occurs. In a preferred embodiment, at least one of the n-phase valve opening operations is defined using one of the following form parameter sets, each defined by three shape parameters i), ii), and iii):

a) Shape parameter set 1:

• i) total amount of fuel (m) injected over the entire n-phase valve opening process,
• ii) partial fuel quantities (m ₁ , m ₂ , m ₃ , ..., m _n ) injected during each phase, and
• iii) duration of the respective phase (T ₁ , T ₂ , T ₃ , ..., T _n )

b) Shape parameter set 2:

• i) total amount of fuel (m) injected over the entire n-phase valve opening process,
• ii) partial fuel quantities (m _1, m _2, m _3, ..., m _n), which are injected during a respective phase, and
• iii) injection rate of the respective phase (r ₁ , r ₂ , r ₃ , ..., r _n )

c) Shape parameter set 3:

• i) total amount of fuel (m) injected over the entire multi-phase valve opening process,
• ii) injection rate of the respective phase (r ₁ , r ₂ , r ₃ , ..., r _n )
• iii) duration of the respective phase (T ₁ , T ₂ , T ₃ , ..., T _n ) wherein from the total number of shape parameters each shape parameter set a total of 2n or 2n-p (depending on the operation without or with full stroke) parameters specified and derived the remaining parameters of the Formparameterschar from this. The total number of shape parameters of each family is the sum of all listed parameters, that is, according to the selection rules of this preferred embodiment, a total of 2n + 1 parameters.

According to this embodiment, the present invention provides that 2n or 2n-p shape parameters are predetermined in the form parameter sets defined above, depending on the mode of operation, and the remaining, non-predetermined shape parameters are derived from the given shape parameters. In this case, for example, the total amount of fuel m, which is injected over the entire multi-phase valve opening process, specified as a shaping parameter. The other parameters that can be specified are either selected from the partial fuel quantities and the durations of the respective phases, the partial fuel quantities and the flow rates or injection rates in the respective phases or the injection rates or flow rates and the durations of the respective phase.

For an exemplary explanation of the method according to the invention is attached to the attached 15b referenced, which provides a 4-phase injection process. In the first injection process, a partial stroke of the needle of the injector, so that fuel is injected at a first injection rate r ₁ . In a subsequent second phase, the injection rate is increased by further opening the valve to r ₂ . In the third phase, a complete opening of the injection valve takes place, so that from this the maximum injection rate r _vh takes place. In a final fourth phase, the injection rate is reduced to r ₃ by partial closure of the injector. Finally, the injector is closed. The duration of the first, second or last injection phase is indicated by T ₁ , T ₂ and T ₃ . The respective quantities of fuel injected during the individual phases of the 4-phase injection process are designated m ₁ , m ₂ , m _vh and m ₃ . The total amount of injected fuel m results from the sum of m ₁ , m ₂ , m _vh and m ₃ . The method can now be controlled in such a way that the total amount of fuel introduced m of all phases is predetermined and, for example, for the first, the second and the last phase respectively the discontinued fuel quantities m ₁ , m ₂ and m ₃ and their respective duration T ₁ , T ₂ and T _{3 are} predefined. From this, for example, the fuel quantity m _vh to be injected in the full-lift phase can be expressed by the following equation m _vh = m - m ₁ - m ₂ - m ₃ derived. Since the rate of Vollhubphase r _{vh is} also known - this is the maximum rate that can be structurally made with a given injector with a given injector - can also be the duration of the third injection phase, the Vollhubphase derived. Overall, 2n - p (with n = 4 and p = 1) are given shape parameters, the remaining shape parameters can be derived from the given shape parameter. Likewise, however, a definition of the individual injection phases is possible by selecting or specifying other shape parameters, such as, for example, the rates and the times or the rates and the injection quantities.

The n-phase valve opening process according to the invention comprises at least two phases (n ≥ 2) in which there is a different or deviating opening position of the injection valve. However, it may also include several phases, for example 3, 4, 5, 6, 7, 8, 9, 10 or more phases. Decisive here is that in each phase fuel is injected with a different from the previous phase injection rate, which according to the invention accomplished by the fact that the opening position of the valve is varied in each case.

Preferably, during at least or exactly one of the n phases of the n-phase valve opening operation, a complete opening of the injection valve (p ≥ 1 or p = 1) takes place, while the fuel is injected at the maximum injection rate (r _vh ).

The inventive method can also be carried out so that during the first phase, only a partial opening of the valve takes place and in a further phase, for. B. in a subsequent phase, another opening, for example, a complete opening of the valve takes place.

The method according to the invention can also be carried out such that during none of the injection phases carried out a full opening of the valve is carried out (i.e., p = 0).

• a) in der ersten Phase das Einspritzventil partiell geöffnet und Kraftstoff mit einer ersten Einspritzrate (r₁) eingespritzt wird und während der sich anschließenden Einspritzphase eine weitere Öffnung des Einspritzventils erfolgt, so dass die Einspritzrate (r₂) während der sich anschließenden Einspritzphase größer ist als die erste Einspritzrate; oder
• b) in der ersten Phase das Einspritzventil ganz geöffnet und Kraftstoff mit der maximalen Einspritzrate (r_vh) eingespritzt wird und während der sich anschließenden Einspritzphase eine partielle Schließung des Einspritzventils erfolgt, so dass die Einspritzrate (r₂) während der sich anschließenden Einspritzphase kleiner ist als die erste Einspritzrate.

Preferred embodiments of the method provide that

• a) in the first phase, the injection valve partially opened and fuel at a first injection rate (r ₁ ) is injected and during the subsequent injection phase, a further opening of the injection valve, so that the injection rate (r ₂ ) during the subsequent injection phase is greater as the first injection rate; or
• b) in the first phase, the injection valve fully open and fuel at the maximum injection rate (r _vh ) is injected and during the subsequent injection phase, a partial closure of the injection valve, so that the injection rate (r ₂ ) during the subsequent injection phase is smaller as the first injection rate.

In particular, the method may be formed, for example, two-phase, during the first phase, the injection valve is initially partially opened and fuel injected at a first injection rate (r ₁ ) and in the second phase, starting from the first opening position of the injection valve, a further opening or a complete opening of the injection valve, so that the injection rate (r ₂ , r _vh ) in the second phase is greater than during the first phase.

In the second phase, a complete opening of the valve can take place, as it is also possible that only a further opening as in the first phase, but not a complete opening is made.

• a) während der zweiten Phase eine höhere Einspritzrate (r₂) als während der ersten Phase (r₁) und während der dritten Phase eine höhere Einspritzrate (r₃, r_vh) als während der zweiten Phase realisiert wird, oder
• b) während der zweiten Phase eine höhere Einspritzrate (r₂, r_vh) als während der ersten Phase (r₁) und während der dritten Phase eine geringere Einspritzrate (r₃) als während der zweiten Phase realisiert wird.

An alternative, but also preferred embodiment of the method according to the invention provides that the valve opening operation is carried out in three phases, wherein

• a) a higher injection rate (r ₂ ) is realized during the second phase than during the first phase (r ₁ ) and during the third phase a higher injection rate (r ₃ , r _vh ) than during the second phase, or
• b) during the second phase, a higher injection rate (r ₂ , r _vh ) than during the first phase (r ₁ ) and during the third phase, a lower injection rate (r ₃ ) is realized than during the second phase.

Particularly preferred in the aforementioned two-phase or three-phase process management is that during the second phase, a complete opening of the injection valve and an injection of the fuel with maximum injection rate (r _vh ) takes place.

In a further alternative embodiment, the valve opening operation can be carried out in four phases, wherein z. For example, during the second phase a higher injection rate (r ₂ ) than during the first phase (r ₁ ), during the third phase a higher injection rate (r ₃ , r _vh ) than during the second phase and during the fourth phase a lower injection rate (r ₄ ) than realized during the third phase.

In this four-phase valve opening, it is preferable if a complete opening of the injection valve and an injection of the fuel with maximum injection rate (r _vh ) takes place during the third phase.

A further advantageous embodiment provides that the injector drive is derived from the mold parameters and a partial lift injector map converts the specifications of a desired injection rate and a fuel pressure into an energy characteristic value of the injector drive.

Alternative and also preferred, the injector control is derived from the shape parameters and a Vollhub injector map the specifications of a desired phase quantity and a fuel pressure in a control period of this phase converted.

The presetting of the 2n-1 shape parameters preferably takes place via an electronic control unit.

It is also advantageous if the specification of the 2n-p shape parameters is dependent on the load and / or speed and / or combustion mode. The shape parameters can be stored, for example, for each speed or load in an electronic memory unit.

In a further preferred embodiment, it is provided that at least one additional valve opening operation is performed during a combustion cycle before and / or after at least one of the multiphase valve opening operations. This embodiment provides that a plurality of injections be made per combustion cycle in the internal combustion engine, wherein at least one of the injection events, which respectively take place via a valve opening operation, according to an injection method according to the invention, wherein a multi-phase valve opening operation is performed as defined above.

According to the invention, a fuel injection system for an internal combustion engine is likewise provided, comprising an injection valve to be actuated with a solenoid valve or piezo actuator for each cylinder of the internal combustion engine, and a control device for actuating the injection valves, wherein the control device is programmed to control the injection valves by a previously described method.

A preferred embodiment provides that the fuel injection system is designed as a common rail injection.

In a further preferred embodiment, the injection valves each have a valve needle which can be moved by the solenoid valve or the piezoactuator as closing elements.

According to the invention, an internal combustion engine is further provided which comprises a fuel injection system according to the invention.

The present invention will be described in more detail with reference to the following embodiments and the attached figures.

It shows

1 a basic rate flexibility of a current injection as well as their injector map according to the prior art;

2 an example of a multiple injection injection pattern per combustion process of the prior art;

3 an injection rate generated according to the present invention;

4 an injection rate pattern with multiple injections per combustion cycle, wherein two of the injection events are carried out according to the method of the invention;

5 two injector maps for injection rate progression according to the method of the invention;

6 two examples of the in 5 illustrated injector maps;

7 two more examples to the in 5 illustrated injector maps;

8th the definition of the first phase of injection rate progression molding;

9 the definition of the second phase of injection rate progression molding;

10 a complex injection pattern based on the three shape parameters;

11 an example of the load, speed and / or mode-dependent specification of the injection process parameters;

12 Setpoint specifications with injection sequence parameters and the function group of the injection realization;

13a) C) possibilities for variation of the three injection curve shape parameters;

14 Measurements of rail pressure variation at constant injection parameters; and

15a) B) a four-phase injection method according to the invention.

For rate shaping according to the invention is a multi-phase, z. B. a two-phase injection, for example via three shape parameters and a position parameter defined (see 3 ). The first phase of the injection, also called boat, is characterized by a needle seat throttled partial lift injection of variable duration and altitude, the amount of the 1st phase being approximately its product. The 2. Phase starts with the rate of the 1st phase and a short second triggering results in a triangular course. For a longer activation, the 2nd phase changes to full-stroke injection. This course is then known as a boat injection.

The rate shaping form parameters now provide the flexibility to represent one and the same amount with very different rate histories. In the prior art, however, the relationship between quantity and shape is rigid.

The definition of the complete injection method is based on three shape parameters, namely the amount of injected fuel, in the sum of the two phases, the amount of injected fuel in the first phase and the duration of the first phase.

In 4 is shown an injection method in which per combustion cycle of the engine, ie per piston stroke, several injections are made, in the example, a total of six injections. Thereby the injections, which are in the 4 with reference marks 3 respectively. 6 are carried out according to the method of the invention, wherein a two-phase injection method is performed, which is operated in the first phase with a reduced injection rate and in the second phase with an increased injection rate.

5 shows two injection maps for injection rate progression, on the basis of which the exact shape of a respective two-phase injection method can be tuned. The first phase (boat) is specified by the desired Teilhubeinspritzrate and the rail pressure. In order to realize setpoint at a given rail pressure by injector control required for this purpose, a partial lift injector map converts these specifications into an energy characteristic value of the injector control. Experiments have shown that the injector behavior can be well represented. The necessary control is proportional to the required needle stroke and the hydraulic counterforce with a good approximation. Existing non-linearities are detected via the map according to the invention. The energy characteristic value can be determined, for example, such that the charge state Q and the voltage state U are measured in the partial stroke and the energy is formed via E = 0.5 · Q · U.

The injector drive of the second phase can be determined by a second injector map such that the desired fuel quantity or mass to be injected in the second phase and the given fuel pressure are converted via the map into the injector drive duration of the second phase required for this purpose.

The partial lift injector map accordingly 5 Clamps a map on the desired Teilhubeinspritzrate and rail pressure. For each pair of values [rate, pressure], an energy characteristic value is stored which takes into account the injector characteristic so that the adjusted energy value of the piezoactuator lifts the injection needle out of the seat just enough to realize the desired partial stroke injection rate. From the examples in 6 It can be seen that with increasing rail pressure the energy value increases because the piezoactuator works against an increasing hydraulic force. In addition, the energy characteristic increases with increasing Teilhubrate because the piezoelectric actuator, the injection needle must continue to lift out of the seat. For each Teilhubphase the Teilhub injector map is evaluated. The determined energy characteristics are advantageously set injector-individual, injection-individual and phase-specific for each partial stroke, via a control of actuator voltage and charge. In 6 Two examples of different nozzles are given.

This in 5 shown injector map for the full-stroke phase spans a map on Vollhubphasenmenge and rail pressure. For each pair of values [quantity, pressure], a control period is stored which also takes into account the injector characteristic. With increasing amount, the driving time increases. With increasing rail pressure, the activation duration decreases due to the higher flow rate. In contrast to the classic injector map, the full-stroke-phase injector map implies the existing partial stroke of the injector, ie an increase in quantity is present at the beginning of the activation period.

7 For example, represents both injector maps in a calibration environment, partial lift injector map on the left and full stroke injector map on the right.

In 8th is a method for injection rate shaping specified in which two independent parameters are given and a dependent parameter sets. For example, at the in 8th injection rate history shaping the boot quantity and boot duration during the first phase (Boot) given, from a further predetermined total amount, the injection rate of the second phase can be derived.

In 9 the definition of injection rate progression over the second phase. In this case, the fuel quantity to be injected in the second phase is determined from the difference between the predetermined total fuel quantity injected in the injection pulse according to the invention and the quantity which is injected during the first phase (boat). The start of the second phase is predetermined by the injection position.

The inventive method provides a technological advance that is comparable to the transition from the former single injection to today established multiple injection. The invention gives the step in a new universally applicable rate shaping. Flexibility continues to increase with any combination of "primitives" such as shown in the following measurement. With the three shape parameters of each injection complex injection patterns can be composed, as for example in 10 is pictured. In the under 10 A breakdown of the injected amounts or times is defined as each pulse over the total injected fuel amount (uppermost value), the injected fuel quantity in the first phase (middle value), and the first phase duration (lowest value). For example, the fuel injection process ("Main 2") carried out according to the invention is carried out such that a total amount of fuel injected during the entire injection process, namely 20 mg, is predetermined. Of this, 2 mg of injected fuel accounts for the first phase, which has a predetermined duration of 300 μs. From this, it is possible to derive the quantity of fuel injected during the second phase as well as the duration, in the event that a complete opening of the valve takes place, as in the present case.

For each injection, the injection position and three shape parameters are stored in the so-called "Combustion Manager" depending on the load and speed and can also be specified depending on the combustion mode. This gives the general applicability.

11 shows an example of the load (TQI SP), speed (N) and / or mode (M) dependent specification of the injection process parameters. The requirements on the course of injection and the course of the rates vary greatly with regard to load, speed and temperature. In addition, there are special requirements for the regeneration of exhaust aftertreatment filters and / or catalysts. This multidimensional dependency of optimum shape parameters can preferably be stored in maps via speed and load, in which case the further dependencies are taken into account by switching over and / or interpolating other maps, depending on the mode of operation.

In 12 is the realized control and regulating structure, in particular the setpoint specifications with injection sequence parameters and the functional group of injection realization shown.

In 13 Several variants are shown how an injection process can be designed based on the three parameters defined above. According to the in 13a The method shown, the duration of the first injection phase, the so-called boot phase, ie the phase in which there is no complete valve opening, kept constant. Likewise, the injected amount of fuel is kept constant in the first phase. The total amount is now varied by varying the injected amount of fuel in the second phase, ie the phase in which there is a complete opening of the valve.

In the statements according to 13b There is a variation of the amount of fuel injected in the first phase (boat). However, the total amount of fuel that is injected into the engine during the injection process is kept constant, ie, depending on the amount of fuel injected in the first phase, the duration of the second injection phase, in which there is a complete opening of the valve, is varied.

In 13c the duration of the first phase (boat) is varied, however, the amount of fuel injected in the first phase is kept constant by selecting different partial valve opening states. Likewise, the total amount of fuel injected during the injection process is kept constant.

14 shows that the needle stroke of the injector is readjusted, because despite Raildruckvariation between 20 and 160 MPa approximately a constant rate of the 1st phase (boat) is realized. In contrast, the rate of the 2nd phase continuously increases with the rail pressure, since the 2nd phase is characterized by a full stroke. Only if the 2nd phase has a sufficiently small quantity specification, it goes into a ballistic operation, as in 13a ) is shown. In order to comply with the constant quantity specification, the second phase is adjusted here in accordance with the specification of the second injection course injector map (cf. 5 ). The mode of operation of the first injector map can be seen indirectly from the voltage increase of the 1st phase. The injector energy is raised according to the rail pressure.

In addition to the previously described combinations of various parameters for controlling the injection method of the present invention, however, further parameter combinations are possible. By specifying certain shape parameters of the injection rate, dependent parameters may result, parameters derived or dependent on the given parameters. For example, the following parameter combination options are conceivable: parameter specifications Derived parameters Quantity Subset of the 1st phase Duration of the 1st phase Subset of the 2nd phase rate *) of the 1st phase Subset of the 1st phase Subset of the 2nd phase Duration of the 1st phase Quantity 1st phase rate Quantity Subset of 1st Phase 1st Phase Rate Subset of the 2nd phase Duration of the 1st phase Quantity Duration of the 1st phase 1st phase rate Subset of the 1st phase Subset of the 2nd phase *) Injector flow rate z. In [mg / ms]

Furthermore, more complex injection forms are conceivable, which can be described by other shape parameters. Generalized multi-phase rate shaping includes, as a subset, biphasic rate shaping. The 15a) and 15b) exemplify the 4-phase Ratentenverlaufsformung, wherein a practically useful application consists of two first Teilhubphasen, a third main phase and a final fourth Teilhubphase. Each additional phase (these are the partial lift phases) must be described with two additional shape parameters.

• • Menge (aller Phasen),
• • jede zusätzliche Phase wird durch Menge m_i und Dauer T₁ definiert,
• • p = Anzahl der Vollhubphasen.

An n-phase injection has (2n-p) shape parameters:

• • quantity (of all phases),
• Each additional phase is defined by set m _i and duration T ₁ ,
• • p = number of full-stroke phases.

15a illustrates a principal course and variation possibilities of the injection rate of a four-phase injection method according to the present invention. During the first, the second and the fourth phase, a reduced injection rate is used than the injection valve with full opening of the injection valve. Such injection procedures can be referred to as Nadelteilhub or simply as a partial stroke. During the third phase, a full opening of the injector takes place so that injection is at maximum injection rate. Such a phase can be referred to as Nadelvollhub or simply as Vollhub.

In 15b is shown how the injected fuel quantities can be calculated during the four phases. The injected quantities of fuel can be calculated by integrating the injection rate with the respective duration of the respective phase. The fuel quantities, in particular the total amount M, can therefore be calculated by multiplying the respective injection rates r ₁ , r ₂ and r ₃ by the respective phase durations T ₁ , T ₂ and T ₃ .

Claims (20)

Method for injecting pressurized fuels into an internal combustion engine by means of an injection valve, wherein during a combustion cycle the fuels are injected into the internal combustion engine via at least one valve opening operation of the injection valve, wherein at least one of the valve opening operations is configured n-phase with n ≥ 2, so that in a first phase the Injection valve initially partially or completely open and fuel at a first injection rate (r ₁ ) is injected, which is followed by at least one additional phase, wherein the injection valve occupies a different from the previous phase opening position during the at least one further phase so that fuel with injection rate (r ₂ , r ₃ ,..., r _n ) deviating in each case from the preceding injection rate and closing of the injection valve takes place, the course of the at least one of the n-phase valve opening events being represented by the following set of general shape parameters is defined: total fuel amount (m) injected in the entire n-phase valve opening operation, partial fuel quantities (m ₁ , m ₂ , m ₃ ,..., m _n ) injected during each phase of the n-phase valve opening operation - duration of the respective phase (T ₁ , T ₂ , T ₃ , ..., T _n ) of the n-phase valve opening operation, which is specified via the respective opening position of the injection valve and the pressure of the fuel, injection rate of the respective phase (r ₁ , r ₂ , r ₃ , ..., r _n ) of the n-phase valve opening operation , which is specified via the respective opening position of the injection valve and the pressure of the fuel, characterized in that in the event that during the at least one n-phase valve opening operation in any phase, a complete opening of the injection valve, from the above-defined amount of all Form parameter 2n predetermined shape parameters and the remaining parameters are derived from the predetermined parameters, or for the case that during the at least one n-phase valve opening operation in p phases, with p <n, a complete opening of the injection valve, while the fuel with the maximum injection rate (r _vh ) is injected, from the above d efined set of all shape parameters 2n - p shape parameters specified and the remaining parameters are derived from the predetermined parameters and that the injector is derived from the shape parameters and a Teilhub injector map converts the specifications of a target injection rate and a fuel pressure into an energy characteristic of injector control. A method according to claim 1, characterized in that the course of at least one of the n-phase valve opening operations is defined using one of the following form parameter sets, each defined by three shape parameters: a) shape parameter set 1: i) total fuel amount (m), the total n ii) partial fuel quantities (m ₁ , m ₂ , m ₃ ,..., m _n ) injected during a respective phase, and iii) duration of the respective phase (T ₁ , T ₂ , T ₃ , ..., T _n ); b) shape parameter set 2: i) total fuel quantity (m) injected over the entire n-phase valve opening process, ii) partial fuel quantities (m ₁ , m ₂ , m ₃ , ..., m _n ) injected during a respective phase and iii) injection rate of the respective phase (r ₁ , r ₂ , r ₃ , ..., r _n ); c) shape parameter set 3: i) total fuel quantity (m) injected over the entire multi-phase valve opening process, ii) injection rate of the respective phase (r ₁ , r ₂ , r ₃ , ..., r _n ) iii) duration of the respective phase (T ₁ , T ₂ , T ₃ , ..., T _n ). Method according to one of the preceding claims, characterized in that the valve opening operation comprises n phases, with 2 ≤ n ≤ 10, preferably 2 ≤ n ≤ 4, wherein during each phase fuel having a different from the previous phase injection rate (r ₁ , r ₂ , r ₃ , ..., r _n ) is injected. Method according to one of the preceding claims, characterized in that during at least or exactly one of the n phases of the n-phase valve opening operation, a complete opening of the injection valve, while the fuel is injected at the maximum injection rate (r _vh ), takes place. Method according to one of the preceding claims, that a) in the first phase, the injection valve partially opened and fuel with a first injection rate (r ₁ ) is injected and during the subsequent injection phase, a further opening of the Injector takes place, so that the injection rate (r ₂ ) during the subsequent injection phase is greater than the first injection rate; or b) in the first phase, the injection valve is fully opened and fuel injected at the maximum injection rate (r _vh ) and during the subsequent injection phase, a partial closure of the injection valve, so that the injection rate (r ₂ ) during the subsequent injection phase smaller is considered the first injection rate. Method according to one of claims 1 to 4, wherein the valve opening operation is formed in two phases, wherein during the first phase, the injection valve is initially partially opened and fuel at a first injection rate (r ₁ ) is injected and in the second phase, starting from the first opening position of the injection valve, a further opening of the injection valve takes place, so that the injection rate (r ₂ , r _vh ) is greater in the second phase than during the first phase. Method according to one of claims 1 to 4, characterized in that the valve opening operation is carried out in three phases, wherein a) during the second phase, a higher injection rate (r ₂ ) than during the first phase (r ₁ ) and during the third phase, a higher injection rate (r ₃ , r _vh ) than realized during the second phase, or b) during the second phase a higher injection rate (r ₂ , r _vh ) than during the first phase (r ₁ ) and during the third phase a lower injection rate ( r ₃ ) than during the second phase is realized. A method according to claim 6, characterized in that during the second phase, a complete opening of the injection valve and an injection of the fuel with maximum injection rate (r _vh ) takes place. Method according to one of claims 1 to 5, characterized in that the valve opening operation is carried out in four phases, wherein during the second phase, a higher injection rate (r ₂ ) than during the first phase (r ₁ ), during the third phase, a higher injection rate (r ₃ , r _vh ) than during the second phase and during the fourth phase a lower injection rate (r ₄ ) is realized than during the third phase. Method according to the preceding claim, characterized in that during the third phase, a complete opening of the injection valve and an injection of the fuel with maximum injection rate (r _vh ) takes place. Method according to one of the preceding claims, wherein the specification of the energy characteristic value is calculated and set for each partial stroke injector-individual, injection-individual and / or phase-individual. Method according to one of the preceding claims, wherein the setting of the energy characteristic is injector-individual, injection-individual and / or phase-individually controlled, and the actual value energy is formed from a combination of actuator voltage and charge. Method according to claims 1 to 10, characterized in that the injector control is derived from the shape parameters and a full-stroke injector map converts the specifications of a desired phase quantity and a fuel pressure into a control period of this phase. Method according to the preceding claim, characterized in that the specification of the 2n-p shape parameters takes place via an electronic control unit. Method according to one of the two preceding claims, characterized in that the specification of the 2n or 2n - p shape parameters load and / or speed dependent and / or Verbrennungsmodderabhängig takes place. Method according to one of the preceding claims, characterized in that at least one additional valve opening operation is performed before and / or after at least one of the multi-phase valve opening operations. Fuel injection system for an internal combustion engine, comprising for each cylinder of the internal combustion engine each having a solenoid valve or piezo actuator to be actuated injection valve and a control device for driving the injection valves, wherein the control device programmatically for controlling the injection valves by a method according to one of the preceding claims set is. Fuel injection system according to the preceding claim, characterized in that it is designed as a common rail injection. Fuel injection system according to one of the two preceding claims, characterized in that the injection valves as closure elements each have a movable by the solenoid valve or the piezo-actuator valve needle. An internal combustion engine comprising a fuel injection system according to any one of claims 17 to 19.

Images