Method for determining the progress of internal pressure of a cylinder in an internal combustion engine

• US 6,188,952 B1
• Filed: 02/19/1999
• Issued: 02/13/2001
• Est. Priority Date: 02/20/1998
• Status: Expired due to Term

• Current Assignee: Magneti Marelli S.p.A.
• Original Assignee: Magneti Marelli S.p.A.
• Inventors: Serra, Gabriele, Azzoni, Piero, Rossi, Carlo, Minelli, Giorgio, Moro, Davide
• Primary Examiner(s): Dolinar, Andrew M.
• Application Number:
  US09/253,557
• Time in Patent Office: 725 Days
• Field of Search: 701/102, 701/114, 701/103-105, 73/115, 73/116, 73/117.3, 73/49.7, 123/406.24, 123/406.25, 123/436
• US Class Current: 701/103
• CPC Class Codes: F02B 77/08 Safety, indicating or supervising devices thermal insulation F02B77/11; rendering engines inoperative or idling F02D17/04; dependent on lubricating conditions F01M1/22; dependent on cooling F01P11/14
• CPC Class Codes: F02D 2041/1433 using a model or simulation of the system
• 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 35/024 using an estimation
• CPC Class Codes: G01M 15/046 by monitoring revolutions for detecting misfire G01M15/11

Abstract

Method for determining the progress of internal pressure of a cylinder in an internal combustion engine, defining for each combustion cycle of the engine, the phases of defining the effective operating point of the engine according to the value assumed by a number of operational parameters of the engine; recording the progress of immediate angular speed of the engine shaft; calculating a transfer function involving the angular speed and the internal pressure of the cylinder at the effective defined operational point, on the basis of a plurality of reference transfer functions between internal pressure and angular speed relative to reference operating points of the engine; and deriving the progress of internal pressure at the cylinder of the transfer function at the actual operating point and of the progress of angular speed.

Claims

1. Method for controlling an internal combustion engine having a shaft, an intake manifold, a fuel supply device, an ignition device and at least one cylinder, the method comprising:

defining an plurality of operating points of the engine based on an average angular speed of the engine shaft and an average pressure at the intake manifold of the engine;

recording an instantaneous angular speed of the shaft;

defining, in relation to each operating point of the engine, a transfer function relating the instantaneous angular speed of the shaft to an internal pressure to the cylinder;

determining the internal pressure to the cylinder based on the instantaneous angular speed of the shaft and at least one of the transfer functions; and

controlling the fuel supply device and the ignition device based on the internal pressure to the cylinder.

2. Method according to claim 1, wherein the transfer function is a frequential response involving the internal pressure and the instantaneous angular speed of the shaft.

3. Method according to claim 1, wherein the recording of the instantaneous angular speed of the shaft comprises sampling, for each combustion cycle of the engine, the instantaneous angular speed in accordance with a plurality of sampling moments thereby obtaining a plurality of measured values.

4. Method according to claim 3, wherein the determining the internal pressure to the cylinder comprises:

calculating the Fourier discrete transformation of instantaneous angular speed according to the plurality of measured values;

applying the transfer function to the Fourier transformation of angular speed to obtain the Fourier transformation of internal pressure to the cylinder;

calculating the Fourier anti-transformation of the Fourier internal pressure to obtain the Fourier transformation of internal pressure to obtain a plurality of values estimated from the internal pressure at the sampling moments of the instantaneous angular speed;

the plurality of values estimated from the internal pressure defining the internal pressure to the cylinder.

5. Method according to claim 3, wherein the sampling of the instantaneous angular speed is effected, at each combustion cycle of the engine, in a time interval wherein a piston associated with the cylinder moves in a preset manner to a top dead center position during the engine ignition phase.

6. Method according to claim 1, wherein the transfer function between the internal pressure and the instantaneous angular speed of the engine shaft at the operating point of the engine is calculated by processing the transfer function corresponding to an actual operating point of the engine.

7. Method according to claim 1, further comprising for each cycle of the engine, deducing a torque transmitted to the engine shaft based on the internal pressure to the cylinder.

8. Method for controlling an internal combustion engine having a shaft, an intake manifold, a fuel supply device, an ignition device and at least one cylinder, the method comprising:

defining an plurality of operating points of the engine, wherein an average angular speed of the engine shaft and an average internal pressure at the intake manifold define a plane of possible operating points of the engine;

each of the operating points of the engine being represented by a respective point of the plane;

the reference operating points of the engine defining a grid on the plane;

recording an instantaneous angular speed of the shaft;

defining, in relation to each operating point of the engine, a transfer function relating the instantaneous angular speed of the shaft to an internal pressure to the cylinder;

determining the internal pressure to the cylinder based on the instantaneous angular speed of the shaft and at least one of the transfer functions; and

controlling the fuel supply device and the ignition device based on the internal pressure to the cylinder.

9. Method according to claim 8, wherein on the grid a sub-assembly of the reference operating points comprising the reference points closest to an actual operating point is defined on the plane;

the transfer function at the actual operating point being calculated as an average set of reference transfer functions relating to the reference operating points of the sub-assembly, each reference transfer function intervening in the average set according to a weight which is a function of the Euclidean distance between the relative reference operating point and the actual operating point.

10. Method according to claim 8, wherein the transfer function is a frequential response involving the internal pressure and the instantaneous angular speed of the shaft.

11. Method according to claim 8, wherein the recording of the instantaneous angular speed of the shaft comprises sampling, for each combustion cycle of the engine, the instantaneous angular speed in accordance with a plurality of sampling moments thereby obtaining a plurality of measured values.

12. Method according to claim 11, wherein the determining the internal pressure to the cylinder comprises:

calculating the Fourier discrete transformation of instantaneous angular speed according to the plurality of measured values;

applying the transfer function to the Fourier transformation of angular to obtain the Fourier transformation of internal pressure to the cylinder;

calculating the Fourier anti-transformation of the Fourier internal pressure to obtain the Fourier transformation of internal pressure to obtain a plurality of values estimated from the internal pressure at the sampling moments of the instantaneous angular speed;

the plurality of values estimated from the internal pressure defining the internal pressure to the cylinder.

13. Method according to claim 11, wherein the sampling of the instantaneous angular speed is effected, at each combustion cycle of the engine, in a time interval wherein a piston associated with the cylinder moves in a preset manner to a top dead center position during the engine ignition phase.

14. Method according to claim 8, wherein the transfer function between the internal pressure and the instantaneous angular speed of the engine shaft at the operating point of the engine is calculated by processing the transfer function corresponding to an actual operating point of the engine.

15. Method according to claim 8, further comprising for each cycle of the engine, deducing a torque transmitted to the engine shaft based on the internal pressure to the cylinder.

16. A control unit for an internal combustion engine having a shaft, an intake manifold, a fuel supply device, an ignition device and a plurality of cylinders, the control unit comprising:

a sensor to be attached to the engine; and

a processing unit in cooperation with the sensor, the processing unit configured;

to receive from the sensor a signal reflecting an angular speed of the shaft;

to store a plurality of predefined transfer functions relating to operating points of the engine, each said operating point based on an average angular speed of the engine shaft and an average pressure at the intake manifold;

to determine, for each cylinder, an internal pressure to the cylinder based in part on the angular speed signal and at least one of the predefined transfer functions; and

to control the fuel supply device and the ignition device based on the internal pressure to the cylinder.

17. A control unit for an engine having a shaft, an intake manifold, a fuel supply device, an ignition device and a plurality of cylinders, the control unit comprising:

a sensor to be attached to the engine;

means for receiving from the sensor an angular speed of the shaft signal;

means for storing a plurality of predefined transfer functions relating to operating points of the engine, each said operating point based on an average angular speed of the engine shaft and an average pressure at the intake manifold;

means for determining, for each cylinder, an internal pressure to the cylinder based in part on the angular speed and at least one of the predefined transfer functions; and

means for controlling the fuel supply device and the ignition device based on the internal pressure to the cylinder.