Method for adaptation of a detected camshaft position, control unit for carrying out the method, internal combustion engine, and vehicle

Abstract

A method for adaptation of a detected camshaft position of a camshaft in an internal combustion engine with: Detection of an ACTUAL gas signal in a gas space that is associated with the camshaft and is associated with a detected camshaft position; Processing of the gas signal to produce an ACTUAL gas criterion; Modeling of multiple simulated gas criteria, each of which is associated with a target camshaft position; Determination of a simulated gas criterion with the least deviation from the ACTUAL gas criterion; Determination of an ACTUAL camshaft position that corresponds to the simulated gas criterion with the least deviation from the ACTUAL gas criterion; Determination of a camshaft position correction value from the difference between the ACTUAL camshaft position determined and the detected camshaft position; Determination of corrected camshaft positions by correcting the detected camshaft positions with the camshaft position correction value.

Claims

1. A method for adaptation of a detected camshaft position of a camshaft in an internal combustion engine, the method comprising: detecting an ACTUAL gas signal in a gas space that is associated with the camshaft and is associated with a detected camshaft position; processing the gas signal to produce an ACTUAL gas criterion; modeling multiple simulated gas criteria, which are associated with a target camshaft position; comparing the simulated gas criteria with the ACTUAL gas criterion; determining a simulated gas criterion with the least deviation from the ACTUAL gas criterion; determining an ACTUAL camshaft position that corresponds to the simulated gas criterion with the least deviation from the ACTUAL gas criterion; determining a camshaft position correction value from the difference between the ACTUAL camshaft position determined and the detected camshaft position; and determining at least one corrected camshaft position by correcting the detected camshaft positions with the camshaft position correction value.

2. The method according to claim 1, wherein the at least one corrected camshaft positions of an intake camshaft and/or an exhaust camshaft is determined.

3. The method according to claim 1, further comprising: modeling a valve position criterion of an intake and/or exhaust valve on the basis of the corrected camshaft positions.

4. The method according to claim 3, further comprising: modeling a gas charge on the basis of the modeled valve position criteria.

5. The method according to claim 1, wherein the detected camshaft position is determined in relation to a crankshaft position via a camshaft and crankshaft position sensor arrangement.

6. The method according to claim 4, wherein the camshaft and/or crankshaft position sensor arrangement includes an inductive speed sensor, a differential Hall sensor, a AMR sensor, and/or a Hall phase sensor.

7. The method according to claim 1, wherein the ACTUAL gas signal is an ACTUAL pressure signal.

8. The method according to claim 1, wherein the ACTUAL gas signal is detected as an intake pipe pressure behavior signal in an intake manifold.

9. The method according to claim 1, wherein the ACTUAL gas signal is detected as an exhaust pipe pressure behavior signal in an exhaust manifold.

10. The method according to claim 1, wherein the processing of the ACTUAL gas signal to produce a gas criterion is accomplished via a signal filtering method, a FFT filtering method, or a bandpass filtering method.

11. The method according to claim 1, wherein the generation of the simulated gas criteria is accomplished via a computer-implemented modeling method, a neural network, a Gaussian process model, a polynomial model, or an inverse FFT.

12. The method according to claim 1, wherein at least one of the following computer-implemented comparison methods is performed in order to determine an ACTUAL camshaft position: a cross-correlation method, a standard deviation, or an averaging.

13. An engine control unit adapted to carry out the method according to claim 1.

14. An internal combustion engine comprising: an intake valve arrangement and an exhaust valve arrangement for setting a gas quantity; and an engine control unit according to claim 13.

15. A vehicle comprising an internal combustion engine according to claim 14.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

(2) FIG. 1 is a schematic representation of a motor vehicle with an internal combustion engine for carrying out the method according to the invention;

(3) FIG. 2 is a schematic block diagram with the individual function blocks for carrying out the method according to the invention;

(4) FIG. 3 shows the signal behavior of an ACTUAL pressure signal and ACTUAL pressure criterion;

(5) FIG. 4 shows the ACTUAL pressure criterion;

(6) FIG. 5 shows the ACTUAL pressure criterion together with a family of simulated pressure criteria; and

(7) FIG. 6 shows the behavior of the standard deviation of the differences between individual pressure criteria and the ACTUAL pressure criterion for determining a camshaft position correction value.

DETAILED DESCRIPTION

(8) In a schematic representation, FIG. 1 shows a vehicle 100 with an internal combustion engine 1 that has the following: fresh air or fresh gas is carried into the combustion chamber 5 of the cylinder 6 through an intake manifold 2, which runs between a throttle valve 3 and an intake valve 4. The motion of the intake valve 4 is controlled through the adjustable intake camshaft 7. Fuel is mixed with the supplied fresh air in the cylinder 6 or in the intake manifold 2 and is combusted in the cylinder, driving the piston 8 in the process. The piston movement is transmitted by the crank 9 to the crankshaft 10, whose rotary motion is used by means of a drive train to drive the vehicle 100.

(9) Following the combustion, the piston 8 pushes the exhaust gas out of the combustion chamber 5 through the exhaust valve 11 into the exhaust manifold 12, whence it continues through the turbine 13 of an exhaust turbocharger, which may optionally be equipped with a wastegate valve or a variable turbine geometry. The exhaust valve 11 is driven by the exhaust camshaft 14. The crankshaft 10 drives the exhaust camshaft 14 and the intake camshaft 7 through a drive belt 15, and thus also operates the intake valve 4 and the exhaust valve 11.

(10) The rotary motions of the crankshaft 10 are detected by a crankshaft sensor 16, and the rotary motions of the camshafts 7, 14 are detected by an intake camshaft sensor 17 and an exhaust camshaft sensor 18, respectively. These sensors provide corresponding signals to an engine control unit 19. One or more gas signal sensors 20, 21 for detecting a gas signal or a signal behavior S.sub.ACT are arranged in the region of the intake manifold or in the region of the exhaust manifold. In the present example, these are pressure sensors, which detect an intake pressure p.sub.2 and an exhaust gas back pressure p.sub.3, respectively.

(11) In other embodiments, the corresponding gas signals S.sub.ACT can also be a volume flow rate or a temperature behavior, which then are detected and recorded by other suitable, corresponding sensors, and are provided to the engine control unit 19.

(12) The sequence of the method is now explained by way of example on the basis of FIGS. 2 to 6. The block diagram shows a detection control block A, which is present in a production engine control unit 19, and a special control block B, which is provided specifically for implementing the method according to the invention.

(13) First, an adaptation release takes place in block B1. For this purpose, a defined operating state of the internal combustion engine 1 is queried. For this purpose, the engine is in an operating state in which no fuel is being supplied or injected. In addition, the operating positions of the throttle valve 3 and of any wastegate valve that may be present, or the position of a variable turbine geometry, are queried, all of which must be within a defined range. The ambient pressure p.sub.1 and the temperature T.sub.2 in the intake pipe must also be within a defined range. Furthermore, the engine speed n must likewise be within a specified speed range. For this purpose, the speed signals of the crankshaft sensor 16 and (if a temperature sensor is present) a temperature signal T.sub.1 are queried, and the ambient pressure p.sub.1 (outside of the intake pipe) is determined. If the appropriate conditions are present, pressure detection is carried out in block A1. A corresponding detected signal of the pressure sensor 20 in the intake manifold 2 or the exhaust manifold 12 serves this purpose.

(14) The corresponding signal behavior for this ACTUAL gas signal S.sub.ACT is shown in FIG. 3. In the filter component B2, this gas signal S.sub.ACT is then processed by means of an electronic filter (for example a bandpass filter, an FFT filter, or the like) and is output as an ACTUAL gas criterion. The behavior of the ACTUAL gas criterion is shown in FIG. 3, and exhibits a significantly reduced information and data density, but allows characteristic signal data to be examined.

(15) FIG. 4 shows the behavior of the ACTUAL gas criterion in isolation. The behaviors in FIG. 3 and FIG. 4 are each plotted over crankshaft angle. The ACTUAL gas criterion K.sub.ACT is carried over into a comparison block B5.

(16) For the comparison, a gas criterion K.sub.SIM is then modeled in the modeling block B4, namely taking into account the data for the operating point at which the ACTUAL gas criterion K.sub.ACT has been identified. This information on the operating point or on the reference model is provided by the control block B3. A gas criterion family K.sub.SIM1-n, which is derived from the simulated gas criterion K.sub.SIM, is formed in block B4 in that simulated gas criteria K.sub.SIM are modeled for different camshaft positions Cam.sub.SIM. In this process, the camshaft position is varied virtually between a maximum position Cam.sub.SIMmax and a minimum position Cam.sub.SIMmin. The following can be employed for modeling the gas criterion family K.sub.SIM1-n: neural networks, Gaussian process models, polynomial models, inverse FFT (Fast Fourier Transform), etc.

(17) This gas criterion family K.sub.SIM1-n thus produced is delivered to the comparison block B5, where it is compared with the detected ACTUAL gas criterion (see FIG. 5). The ACTUAL gas criterion (filtered gas signal) K.sub.ACT is compared with all simulated gas criteria K.sub.SIM. Suitable comparison methods are cross-correlation methods, the standard deviation, and the averaging of the differences between the simulated gas criteria K.sub.SIM and the ACTUAL gas criterion K.sub.ACT.

(18) FIG. 6 shows the analysis for a standard deviation a.sub.k. The curve shown is produced in this case from the standard deviations of the differences between different simulated gas criteria K.sub.SIM and the ACTUAL gas criterion. Here, the minimum of the curve between the adjustment angles of 14 and 15 degrees of the camshaft position provides the real ACTUAL camshaft position Cam.sub.ACT for the operating state with the detected camshaft position Cam.sub.det for which the ACTUAL gas criterion K.sub.ACT was determined. Thus, the camshaft position correction value Cam.sub.corr results from the difference between the detected camshaft position and the determined ACTUAL camshaft position Cam.sub.ACT. All detected camshaft positions can now be corrected with this value so that they correspond to the real ACTUAL camshaft position, on the basis of which the appropriate control data can then be retrieved.

(19) Additional variations and exemplary embodiments are evident to the person skilled in the art on the basis of the claims. In addition to the pressure behaviors described above, temperature behaviors and/or volume flow rates can also serve as gas signals. The method described here using the example of an intake camshaft can also be applied to an exhaust camshaft. It is also possible to apply the above-described method to other adjustment arrangements for control and adjustment arrangements of the intake and exhaust valves, and thus to derive appropriate valve position criteria K.sub.VS in block A2 (FIG. 2).

(20) The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.