Regulation of true running for diesel engines

• US 20030089338A1
• Filed: 10/22/2002
• Published: 05/15/2003
• Est. Priority Date: 11/07/2000
• Status: Active Grant

• Current Assignee: MTU Friedrichshafen GmbH (Rolls-Royce Holdings Plc)
• Original Assignee: MTU Friedrichshafen GmbH (Rolls-Royce Holdings Plc)
• Inventors: Schneider, Andreas, Debelak, Albrecht, Remele, Joerg
• Granted Patent: US 6,820,593 B2
• Time in Patent Office: Days
• US Class Current: 123/436
• CPC Class Codes: F02D 2041/288 for performing a transformation into the frequency domain, e.g. Fourier transformation
• CPC Class Codes: F02D 2200/1015 Engines misfires
• CPC Class Codes: F02D 41/0085 Balancing of cylinder outputs, e.g. speed, torque or air-fuel ratio
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/009 using means for generating position or synchronisation signals
• CPC Class Codes: F02D 41/1498 measuring engine roughness

Abstract

In internal-combustion engines with large numbers of cylinders, the rotational speed fractions of the cylinders are superimposed such that, when considering a rotational speed curve, no conclusions are possible any longer with respect to rotational speed fractions of individual cylinders. This requires new analyzing methods. According to the invention, contributions of individual cylinders of the internal-combustion engine to the rotational acceleration are determined by the rotational speed course of the crankshaft by individually cutting off the cylinders successively. From the thus obtained rotational speed course curves, a pulse response spectrum {right arrow over (I)} of an operating cycle is formed at least for the harmonic of the 0.5th order. In normal operation, the rotational speed course of the crankshaft is then continuously recorded above the angle of each operating cycle. By a Fourier transformation, Fourier coefficients are determined as a resultant {right arrow over (R)} at least of the harmonic of the 0.5th order. Correction factors for the injection quantities are obtained for equalization of the individual cylinders with respect to their rotational speed fractions. The components of the resultant {right arrow over (R)} situated in the direction of the pulse response vectors are multiplied with the pulse responses {right arrow over (I)} and are combined by addition.

Claims

1. Method of controlling the smooth running of the crankshaft of an internal-combustion engine, the contributions of the individual cylinders of the internal-combustion engine to the rotational acceleration being determined by means of the rotational speed course of the crankshaft, and the injection quantities of the injectors assigned to the cylinders being varied for adjusting defined rotational speed contributions to the rotational speed course,

characterized in that, on the basis of computed or measured rotational speed curves of the crankshaft, for each cylinder, a pulse response spectrum {right arrow over (I)} of an operating cycle is formed at least for the harmonic of the 0.5th order, in that, in the normal operation, in each case, the rotational speed course of the crankshaft is recorded above the angle of an operating cycle recorded and, by a Fourier transformation, the Fourier coefficients is determined as the resultant {right arrow over (R)} at least of the harmonic of the 0.5th order, and in that, furthermore, correction factors for the injection quantities of the individual cylinders are obtained in that the components of the resultant {right arrow over (R)} situated in the direction of the pulse response vectors are multiplied with the pulse responses {right arrow over (I)} and are combined by an addition.

2. Method of controlling the smooth running according to claim 1,

characterized in that the pulse response spectrum {right arrow over (I)} is obtained from the difference between the rotational speed curve of the healthy engine and the rotational speed curve of the engine with one cut-off cylinder respectively for each cylinder by means of the Fourier transformation of the rotational speed difference curve.

3. Method according to claim 1 or 2,

characterized in that the scalar product is formed from the pulse responses {right arrow over (I)} and the Fourier coefficients {right arrow over (R)}, the elements of the scalar product, after the multiplication with the unit vector, representing the correction factors for the injection quantities of each cylinder with respect to the amount and the direction.

4. Method according to claim 1, 2 or 3,

characterized in that the low-frequency fractions of several harmonic waves are averaged from the courses of the curves by means of a Fourier transformation and correction factors are indicated therefrom for the injection quantities of each cylinder.

5. Method according to claim 4,

characterized in that the harmonic waves of the 0.5th to the 3rd order are considered.

6. Method according to claim 4,

characterized in that the Fourier coefficients of the 0.5th and 1st order are used.

7. Method according to claim 5,

characterized in that, in addition, the harmonic waves of the 1.5th order are taken into account.

8. Method according to one of claims 1 to 7,

characterized in that the coefficients of the Fourier transformation are filed and processed in the form of matrices in a vehicle computer.

9. Method according to one of claims 1 to 8,

characterized in that the adjustment of the injection quantities of the individual cylinders of the healthy engine is corrected until the contributions of the cylinders, at least as far as low-frequency harmonics are concerned, are largely equalized for the rotational acceleration, and in that, in comparison to this rotational speed course, the contributions of the individual cylinders to the rotational speed course are determined.