DE102010045517A1 - Method for detecting e.g. diesel in fuel delivery system of internal combustion engine, involves determining density of fuel in fuel delivery system of engine based on resonance frequency of quartz crystal - Google Patents

Abstract

The method involves determining resonance frequency of a quartz crystal (28), which is washed by fuel e.g. diesel, petrol, naphtha, kerosene, alcohol, butanol, methanol, gas to liquid or biomass to liquid, in a fuel delivery system of an internal combustion engine. Density of the fuel in the fuel delivery system of the engine is determined based on the resonance frequency of the quartz crystal. Temperature of the fuel in a region of the quartz crystal and/or temperature of the quartz crystal are determined based on the determination of the frequency of the quartz crystal.

Description

The invention relates to a method for detecting a fuel in a fuel supply system of an internal combustion engine, according to the preamble of patent claim 1.

The use of other liquid fuels or mixtures thereof as the typical fuels, such as diesel and gasoline mixtures, requires in the corresponding engine control strategies for controlling and optimizing the combustion. For the application of the control strategies, the detection of the respectively present in the fuel supply system fuel or the fuel mixture is necessary.

In the case of the operation of an internal combustion engine with different types of fuel or fuel, a determination of the fuel parameters (eg cetane number and boiling position) of the fuel currently present in a fuel supply system is necessary for the simultaneous fulfillment of the objectives comfort, emissions and consumption , This fuel currently present in the fuel supply system is, for example, a pure fuel, such as diesel, gasoline, naphtha, kerosene, alcohol, in particular methanol, GTL (gas to liquid) or BTL (biomass to liquid), butanol or a mixture of at least two pure fuels ,

From the DE 10 2007 052 096 B4 is a method for detecting a type of fuel, which is injected via an injection system in a combustion chamber of an internal combustion engine, known. In this case, in a high-pressure region of the injection system, a pressure is measured over time and integrated in phases during which the high-pressure pump does not deliver fuel, the balance equation of the hydraulic system over a period considered. From characteristic curves of the compressibility modulus and the density as a function of the pressure, which are known for each fuel, the pressure difference from the integrated balance equation is determined using the values for compressibility modulus and density determined from these characteristic curves at a pressure measured in the injection phase in a trial-and-error procedure certainly. The pair of compressibility module and density which best reproduces the pressure difference measured over the considered time range is used to detect the fuel. In other words, within a delivery pause of a fuel pump, a defined injection is triggered with a known amount from a map. Since not nachgefördert, the compressibility of the fuel causes the amount of known pressure and known temperature. The different compressibilities and densities of the different expected fuels are listed in tables. This can be closed by means of the known volume of the high-pressure region of the injection system to the existing fuel.

From the DE 10 2008 026 009 A1 For example, a method for determining the viscosity and elasticity of viscoelastic media by means of acoustoelectric resonators is known. In this case, a function which describes the electrical admittance of the acoustoelectric resonator is optimized by iteratively adapting this function to a measured admittance curve of the acoustoelectric resonator with measurement medium applied thereto. The adjusted function can then be the viscosity and elasticity of the medium to be taken as a parameter.

From the DE 10 2004 008 150 A1 An on-board measurement of fuel properties for engine management is known. In this case, a defined volume of fuel is evaporated by means of a heater. The time and heating energy required for this is measured and used to determine a fuel distillation performance index (DI). The DI value is a measure of fuel volatility and is then used to control the operation of the engine to reduce pollutants and improve performance.

From the DE 40 19 187 C2 It is known to determine a fuel composition by means of a capacitive dielectric sensor which measures the dielectric constant of the fuel.

The invention has for its object to provide a simple and safe method for determining fuel parameters available.

This object is achieved by a method of o. G. Art solved with the features characterized in claim 1. Advantageous embodiments of the invention are described in the further claims.

This is in a method of o. G. Art according to the invention provided that determines a resonant frequency of a lapped by the fuel in the fuel supply system of the engine quartz oscillator and from the resonance frequency, a density of the fuel in the fuel supply system of the internal combustion engine is determined.

This has the advantage that with low complexity, a functionally reliable and rapid detection of relevant for the combustion in the internal combustion engine properties of the fuel is available.

A particularly simple and functionally reliable determination of the density of the fuel is achieved by comparing the specific resonance frequency with a resonant frequency of the quartz crystal in a reference medium, in particular in vacuum or air, and from a difference between these two resonance frequencies, the density of the fuel in the fuel supply system Internal combustion engine is determined.

A particularly fast and functionally reliable determination of the density of the fuel is achieved by reading the density from a table or by determining a known functional equation in which the resonance frequency and density of the fuel are assigned.

A determination of different types of fuel in the fuel, which is present in the fuel supply system of the internal combustion engine, obtained by the fact that from the specific density all present in the fuel in the fuel supply system of the internal combustion engine fuel types, in particular diesel, gasoline, naphtha, kerosene, alcohol, especially methanol, butanol, GTL (gas to liquid) or BTL (biomass to liquid).

For optimal setting of parameters for the combustion, such as injection timing and / or injection parameterization, with regard to the currently present in the fuel supply system of the internal combustion engine from the specific density at least one engine-relevant parameter, in particular a cetane number and / or a boiling position, the fuel in determined the fuel supply system of the internal combustion engine.

To correct the expansion coefficient of the fuel, a temperature of the fuel in the region of the quartz crystal and / or a temperature of the quartz crystal is determined simultaneously with the determination of the resonant frequency, and the density is determined as a function of the resonant frequency and the temperature. In this case, a density of the fuel at a predetermined standard temperature, in particular 15 ° C., is preferably determined by means of the specific temperature.

A particularly rapid and effective adaptation of the combustion to the fuel present in each case in the fuel supply system of the internal combustion engine is achieved in that for predetermined multi-fuel mixtures, in particular mixtures with at least two of the fuel types diesel, gasoline, naphtha, kerosene, GTL (gas to liquid) or BTL ( biomass to liquid), butanol, an energy injection quantity is corrected as a function of the specific resonance frequency.

The invention will be explained in more detail below with reference to the drawing. This shows in the only Fig. A schematic representation of a fuel supply system of an internal combustion engine for carrying out the method according to the invention.

The exemplary embodiment of a fuel supply system for an otherwise not shown internal combustion engine for carrying out the method according to the invention, which is shown in the single FIGURE, comprises a fuel tank 10 , a prefeed pump 12 , a fuel line 14 , an optional filter 16 , a high-pressure pump 18 , a common rail 20 , an injector 22 for each working cylinder (not shown) of the internal combustion engine, a first return 24 from the injector 22 in the fuel tank 10 and a second return 26 from the common rail 20 in the fuel tank 10 , For carrying out the method according to the invention are a quartz crystal 28 and a temperature sensor 30 located locally close together in the fuel supply system. As shown in the single figure, the quartz crystal is 28 and the temperature sensor 30 for example in the fuel tank 10 , in the fuel line 14 downstream of the fuel tank 10 and upstream of the filter 16 or in the fuel line 14 downstream of the filter 16 and upstream of the high pressure pump 18 arranged. The quartz crystal 28 and the temperature sensor 30 are lapped by fuel, so that the fuel is a resonant frequency of the quartz crystal 28 and one of the temperature sensor 30 measured or detected temperature determined. The quartz crystal 28 and the temperature sensor 30 For example, they are designed as a compact unit.

According to the invention, it is provided that a resonance frequency of the quartz crystal surrounded by the fuel in the fuel supply system 28 is determined. Simultaneously with each determination of a resonant frequency of the quartz crystal 28 the temperature sensor detects 30 an instantaneous temperature of the fuel present in the fuel supply system. From a table or a function equation set becomes for the certain resonance frequency of the quartz crystal 28 taking into account an expansion coefficient, determines a density of the fuel currently present in the fuel supply system. From this density, engine-relevant parameters of the fuel, such as cetane number and / or boiling position, derived and settings of the internal combustion engine with respect to the combustion, such as injection parameters, set accordingly.

In contrast to the known fuel sensors, the fuel detection described here is characterized by its low complexity. The density of a binary fuel mixture is determined by means of the quartz crystal 28 based on in Dependence of the density changing resonant frequency determined. A quartz crystal surrounded by fuel changes its resonance frequency as a function of the fuel density, which can be detected electrically.

The properties of the two fuels (densities A and B) and the interpolation law of the fuel densities A and B are known, the mixture-specific (density C of components A and B with the densities A and B) and engine-relevant parameters (cetane number, Siedelage) thereof be determined. These engine-relevant properties are stored in the control unit and assigned to the correspondingly determined mixture density C. Thus, the necessary parameters of the injection can be adjusted as a function of known variables, such as, for example, ignition delay, injector characteristics and / or minute quantity behavior.

Optionally, in multi-fuel mixtures using the quartz crystal 28 corrects the energy injection quantity if the density of these fuels correlates well with the volume calorific value. This means that the mass-related calorific value is approximately constant. For example, this is the case for different boiling cuts of a hydrocarbon mixture. The correction of the necessary amount of injected energy can preferably be applied to the following fuels and their mixtures: Otto, Diesel, Naphtha, Kerosene, GTL, BTL. One exception to this is, for example, multi-fuel mixtures of gasoline and alcohols. Here, with a similar density, a different calorific value and possibly a different cetane number are present. This fuel mixture can not be safely assigned with this principle, ie regulated to the same calorific value per engine cycle.

The installation of the quartz crystal 28 takes place within a component of the fuel supply system (tank 10 , Low pressure line 14 , Common rail 20 or filter 16 as in the only Fig. For the components 28 and 30 indicated by dashed lines), which is well traversed by fuel. The fuel temperature is determined by means of the temperature sensor 30 near the quartz crystal 28 to correct the expansion coefficient of the fuel (recalculation to the density at a standard temperature, eg 15 ° C). The fuel densities are tabulated or stored as an equation in a controller.

Alternatively, in addition, a combination with a method for detecting a fuel in a fuel supply system of an internal combustion engine, wherein a displacer is moved in a bubble filled with the fuel in the fuel supply system of the internal combustion engine cavity from a first predetermined position to a second predetermined position, wherein from the for the movement required movement time and / or from the movement force required for the movement at a predetermined speed, a viscosity of the present in the fuel supply system of the internal combustion engine fuel is determined.

This has the advantage that, with low complexity, a functionally reliable detection of properties of the fuel relevant for combustion in the internal combustion engine is available by means of the viscosity.

A particularly good dependence of the movement time and / or the motive force on the viscosity of the fuel in the fuel supply system of the internal combustion engine is achieved in that the displacer is moved in the cavity such that in a gap between the displacer and the cavity, a shear flow of the fuel results.

A particularly accurate determination of the viscosity by means of a movement time over a predetermined distance with constant motive force is achieved by moving the displacer in the form of a piston in the cavity in the form of a capillary tube, the plunger being driven by a spring with constant motive force from the first predetermined one Position is moved to the second predetermined position and the movement time for the movement from the first predetermined position to the second predetermined position is determined.

An accurate determination of the viscosity in a mechanically simplified structure is achieved in that the displacer is moved in the form of a piston in the cavity in the form of a two-sided open cylinder such that there is a drag flow between the piston and the cylinder, the piston with a constant Speed is moved from the first predetermined position to the second predetermined position and the movement force required for the movement from the first predetermined position to the second predetermined position is determined.

A further improvement in the accuracy of the determination of the viscosity is achieved in that the displacement body is moved in the form of a membrane piston in the cavity in the form of a capillary tube, the diaphragm piston of a spring with a constant motive force (known force-displacement curve is sufficiently constant; Force ideal) from the first predetermined position to the second predetermined position, and the movement time for the movement from the first predetermined position to the second predetermined position is determined.

A bubble-free flow through the cavity with fuel from the fuel supply system of the internal combustion engine is achieved, for example, that a supply of fuel to the cavity via a 2/2-way valve fluidly connected to the fuel supply system of the internal combustion engine and that a drain for fuel from the Cavity is fluidly connected via a check valve with the fuel supply system of the internal combustion engine.

A particularly fast and functionally reliable determination of the density of the fuel is achieved by reading out the viscosity from a table in which assignments of travel time and / or motive force with the viscosity of the fuel are stored.

A determination of different types of fuel in the fuel, which is present in the fuel supply system of the internal combustion engine, obtained by the fact that from the specific viscosity all present in the fuel in the fuel supply system of the internal combustion engine fuel types, in particular diesel, gasoline, naphtha, kerosene, alcohol, Butanol, in particular methanol, GTL (gas to liquid) or BTL (biomass to liquid), are determined.

For the optimum setting of parameters for the combustion, such as injection time and / or activation time, with regard to the fuel currently present in the fuel supply system of the internal combustion engine, at least one engine-relevant parameter, in particular a cetane number and / or a boiling position, of the fuel in determined the fuel supply system of the internal combustion engine.

To correct the coefficient of expansion of the fuel, a temperature of the fuel in the region of the displacer and / or a temperature of the displacer is determined simultaneously with the determination of the viscosity, and the viscosity is additionally determined as a function of the temperature. In this case, a viscosity of the fuel at a predetermined standard temperature, in particular 15 ° C., is preferably determined by means of the specific temperature.

A particularly fast and effective adaptation of the combustion to the fuel present in each of the fuel supply system of the internal combustion engine achieved by the fact that for predetermined multi-fuel mixtures, especially mixtures with at least two of the fuel types diesel, gasoline, naphtha, kerosene, butanol, GTL (gas to liquid) or BTL (biomass to liquid), an energy injection quantity is corrected as a function of the specific viscosity.

Furthermore, it is in a device of o. G. Art according to the invention provided that this has a bubble-free fillable with the fuel cavity in which a displaceable from a first predetermined position to a second predetermined position displacer is arranged.

This has the advantage that a simple determination of the viscosity of the fuel over a movement time of the displacer at constant acting on this moving force and / or acting on the displacer movement force for a predetermined translational movement, for example, a translational movement at a predetermined speed is achieved.

A particularly high correlation between the movement of the displacer and the viscosity of the fuel present in the cavity is achieved in that the cavity and the displacer are arranged and formed such that upon movement of the displacer in a gap between the displacer and the cavity forms a shear flow.

A mechanically particularly simple structure is achieved in that the displacer is a piston or a diaphragm piston.

A determination of the viscosity of the fuel present in the cavity by means of a movement time for a movement of the displacement of the first predetermined position to a second predetermined position is achieved in that in the cavity, a mechanical spring means, in particular a coil spring, leaf spring or a gas spring, such is arranged and designed such that this mechanical spring means moves the displacer with a predetermined motive force from the first predetermined position to a second predetermined position.

A determination of the viscosity of the fuel present in the cavity by means of a necessary motive force for movement of the displacer from the first predetermined position to a second predetermined position at a predetermined speed can be achieved by arranging and forming in the cavity a mechanical translating device said mechanical translating means moves the displacer at a predetermined speed from the first predetermined position to a second predetermined position.

LIST OF REFERENCE NUMBERS

10

Fuel tank

12

prefeed

14

Fuel line

16

filter

18

High pressure pump

20

Common rail

22

injector

24

first return

26

second return

28

quartz crystal

30

temperature sensor

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

• DE 102007052096 B4 [0004]
• DE 102008026009 A1 [0005]
• DE 102004008150 A1 [0006]
• DE 4019187 C2 [0007]

Claims (8)

A method for detecting a fuel in a fuel supply system of an internal combustion engine, characterized in that a resonant frequency determined by the fuel in the fuel supply system of the internal combustion engine oscillator quartz determines and from the resonance frequency, a density of the fuel in the fuel supply system of the internal combustion engine is determined. A method according to claim 1, characterized in that the specific resonant frequency with a resonant frequency of the quartz crystal in a reference medium, in particular in vacuum or air, compared and from a difference between these two resonant frequencies, the density of the fuel in the fuel supply system of the internal combustion engine is determined. A method according to claim 1, characterized in that the density is read from a table or a function equation or an equation set is determined in the allocations of resonance frequency and density of the fuel are stored. Method according to at least one of the preceding claims, characterized in that from the specific density all fuel types present in the fuel in the fuel supply system of the internal combustion engine, in particular diesel, gasoline, naphtha, kerosene, alcohol, butanol, in particular methanol, GTL (gas to liquid) or BTL (biomass to liquid). Method according to at least one of the preceding claims, characterized in that at least one engine-relevant parameter, in particular a cetane number and / or a boiling position, of the fuel in the fuel supply system of the internal combustion engine is determined from the determined density. Method according to at least one of the preceding claims, characterized in that simultaneously with the determination of the resonance frequency, a temperature of the fuel in the region of the quartz crystal and / or a temperature of the quartz crystal determined and the density in dependence on the resonant frequency and the temperature is determined. A method according to claim 6, characterized in that by means of the determined temperature, a density of the fuel at a predetermined standard temperature, in particular 15 ° C, is determined. Method according to at least one of the preceding claims, characterized in that for predetermined multi-fuel mixtures, in particular mixtures with at least two of the fuel types diesel, gasoline, naphtha, kerosene, GTL (gas to liquid) or BTL (biomass to liquid), butanol, an energy injection quantity is corrected as a function of the determined resonance frequency.

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