Claims
- 1. A method for determining an injection time in a direct-injection internal combustion engine having a high-pressure reservoir containing fuel and connected to an injector so that the fuel injects under control into a cylinder of the internal combustion engine as a function of at least a pressure in the high-pressure reservoir and a required fuel quantity, which comprises the steps of:splitting up a total quantity of the fuel to be fed to the cylinder of the internal combustion engine into at least two injection processes per cylinder stroke; and taking into account pressure fluctuations in the injector occurring between the two injection processes, and in a line between the high-pressure reservoir and the injector when determining the injection time for a next injection process.
- 2. The method according to claim 1, which comprises feeding in the total quantity of the fuel in a pre-injection process and a main injection process, and taking into account the pressure fluctuations initiated by the pre-injection process when determining the injection time for the main injection process.
- 3. The method according to claim 1, which comprises feeding in the total quantity of the fuel in a plurality of pre-injection processes and one main injection process, and taking into account the pressure fluctuations initiated by each of the pre-injection processes when determining the injection time for one of a respectively following pre-injection and the main injection process.
- 4. The method according to claim 3, which comprises using the pressure fluctuations occurring between individual injection processes in each case to determine a correction term with an aid of which the pressure in the high-pressure reservoir is corrected, and determining the injection time with an aid of a corrected pressure value.
- 5. The method according to claim 4, wherein the corrected pressure value is an input variable of a characteristic map in which injection times are stored in dependence on the required fuel quantity.
- 6. The method according to claim 4, which comprises determining the correction term with an aid of a least-squares estimator which, on a basis of an equation of a damped oscillation for the pressure fluctuations determines the injection pressure at a nozzle of the injector in dependence on geometrical data of an injection system and of physical boundary conditions.
- 7. The method according to claim 6, which comprises defining the equation of the damped oscillation for the pressure fluctuations as:y(t)=A·e−d·(t−t0)·sin(2·π·f(t−t0)+φ)·σ(t−t0) whereAis an amplitude of an oscillation,dis a damping factor,t0is a starting instant of the oscillation,fis a frequency,φis a phase, andσ(t − t0)is a jump function at an instant t = 0.
- 8. The method according to claim 7, which comprises using a further equation for determining an estimated pressure characteristic defined by: p(t)= b^2cos(arctan b^1b^2)·e-d·(t-t0)· sin(ω(t-t0)+arctan b^1b^2)·σ(t-t0),whereb1=A·sin φb2=A·cos φ.
Priority Claims (1)
Number |
Date |
Country |
Kind |
198 11 359 |
Mar 1998 |
DE |
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CROSS-REFERENCE TO RELATED APPLICATION
This is a continuation of copending International Application No. PCT/DE99/00652, filed Mar. 10, 1999, which designated the United States.
US Referenced Citations (9)
Non-Patent Literature Citations (1)
Entry |
Patent Abstracts of Japan No. 62-186034 (Daisaku), dated Aug. 14, 1987. |
Continuations (1)
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Number |
Date |
Country |
Parent |
PCT/DE99/00652 |
Mar 1999 |
US |
Child |
09/663587 |
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US |