Method for controlling an internal combustion engine having a camshaft

Abstract

A method according to the invention for controlling an internal combustion engine having a camshaft whose phase with respect to a crankshaft can be adjusted by means of an electric adjustment device, and a control device comprises the steps S1 to S3, wherein in step S1 a stop request is output from the control device to the electric adjustment device. Subsequently, in step S2 a manipulated variable in the form of a pulse duty factor is output from the electric adjustment device, wherein the pulse duty factor counteracts a camshaft torque. In step S3, the direction of rotation of the camshaft is monitored, wherein in step S4, when a reversal of the direction of rotation of the camshaft is detected, an intensity level of this reversal of the direction of rotation is calculated by determining a rotational speed gradient. Furthermore, in a step S5 the pulse duty factor is corrected as a function of the rotational speed gradient in such a way that the influence of the reversal of the direction of rotation on the position of the camshaft is compensated.

Claims

1. A method for controlling an internal combustion engine having a camshaft whose phase with respect to a crankshaft can be adjusted by means of an electric adjustment device, and a control device, the method comprising: S1 outputting a stop request from the control device to the electric adjustment device; S2 outputting a manipulated variable in the form of a pulse duty factor from the electric adjustment device, wherein the pulse duty factor counteracts a camshaft torque; and S3 monitoring the direction of rotation of the camshaft: wherein S4 when a reversal of the direction of rotation of the camshaft is detected, an intensity level of this reversal of the direction of rotation is calculated by determining a rotational speed gradient; and wherein S5 furthermore, the pulse duty factor is corrected as a function of the rotational speed gradient in such a way that the influence of the reversal of the direction of rotation on the position of the camshaft is compensated, wherein the influence of the reversal of the direction of rotation on the pulse duty factor is stored as a function of the rotational speed gradient as a characteristic diagram in the control device, wherein values of the characteristic diagram are added to the pulse duty factor during the compensation of the reversal of the direction of rotation.

2. The method as claimed in claim 1, wherein the detection of the reversal of the direction of rotation takes place by means of a sensor and/or by means of a functional solution in the control device.

3. The method as claimed in claim 2, wherein the outputting of a correction signal is carried out by the control device.

4. The method as claimed in claim 3, wherein the internal combustion engine comprises a camshaft sensor which is connected to the control device, wherein the camshaft sensor transmits a phase edge interrupt of a crankshaft encoder wheel as a signal with high chronological resolution to the control device.

5. The method as claimed in claim 4, wherein the control device carries out the determination of the rotational speed gradient on the basis of this signal with high chronological resolution.

6. The method as claimed in claim 1, wherein the camshaft sensor is integrated into the sensor for detecting the reversal of the direction of rotation, or vice versa.

7. The method as claimed in claim 1, wherein the detection of the reversal of the direction of rotation is carried out by the control device.

8. A camshaft adjustment device for an internal combustion engine having a camshaft and a crankshaft, comprising a control device and at least one sensor, wherein the sensor is configured to provide the control device with information about the direction of rotation of the camshaft, characterized in that the control device is configured to carry out a method comprising: S1 outputting a stop request from the control device to the electric adjustment device; S2 outputting a manipulated variable in the form of a pulse duty factor from the electric adjustment device, wherein the pulse duty factor counteracts a camshaft torque; and S3 monitoring the direction of rotation of the camshaft: wherein S4 when a reversal of the direction of rotation of the camshaft is detected, an intensity level of this reversal of the direction of rotation is calculated by determining a rotational speed gradient; and wherein S5 furthermore, the pulse duty factor is corrected as a function of the rotational speed gradient in such a way that the influence of the reversal of the direction of rotation on the position of the camshaft is compensated, wherein the influence of the reversal of the direction of rotation on the pulse duty factor is stored as a function of the rotational speed gradient as a characteristic diagram in the control device, wherein values of the characteristic diagram are added to the pulse duty factor during the compensation of the reversal of the direction of rotation.

9. The camshaft adjustment device as claimed in claim 8, wherein the camshaft adjustment device comprises a camshaft sensor which is connected to the control device, wherein the camshaft sensor transmits a phase edge interrupt of a crankshaft encoder wheel as a signal with high chronological resolution to the control device.

10. The camshaft adjustment device as claimed in claim 9, wherein the reversal of the direction of rotation is detected by means of a sensor and/or by means of a functional solution in the control device.

11. The camshaft adjustment device as claimed in claim 10, wherein the camshaft sensor is integrated into the sensor for detecting the reversal of the direction of rotation, or vice versa.

12. The camshaft adjustment device as claimed in claim 8, wherein the camshaft sensor is integrated into the sensor for detecting the reversal of the direction of rotation, or vice versa.

13. The camshaft adjustment device as claimed in claim 8, wherein the detection of the reversal of the direction of rotation is carried out by the control device.

14. A motor vehicle having an internal combustion engine having a control device and a camshaft adjustment device, characterized in that the control device is configured to carry out a method comprising: S1 outputting a stop request from the control device to the electric adjustment device; S2 outputting a manipulated variable in the form of a pulse duty factor from the electric adjustment device, wherein the pulse duty factor counteracts a camshaft torque; and S3 monitoring the direction of rotation of the camshaft: wherein S4 when a reversal of the direction of rotation of the camshaft is detected, an intensity level of this reversal of the direction of rotation is calculated by determining a rotational speed gradient; and wherein S5 furthermore, the pulse duty factor is corrected as a function of the rotational speed gradient in such a way that the influence of the reversal of the direction of rotation on the position of the camshaft is compensated, wherein the influence of the reversal of the direction of rotation on the pulse duty factor is stored as a function of the rotational speed gradient as a characteristic diagram in the control device, wherein values of the characteristic diagram are added to the pulse duty factor during the compensation of the reversal of the direction of rotation.

15. The motor vehicle as claimed in claim 14, wherein the camshaft adjustment device comprises a camshaft sensor which is connected to the control device, wherein the camshaft sensor transmits a phase edge interrupt of a crankshaft encoder wheel as a signal with high chronological resolution to the control device.

16. The motor vehicle as claimed in claim 15, wherein detection of the reversal of the direction of rotation takes place by means of a sensor and/or by means of a functional solution in the control device.

17. The motor vehicle as claimed in claim 16, wherein the camshaft sensor is integrated into the sensor for detecting the reversal of the direction of rotation, or vice versa.

18. The motor vehicle as claimed in claim 14, wherein the camshaft sensor is integrated into the sensor for detecting the reversal of the direction of rotation, or vice versa.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described more precisely with respect to the appended figures. In the drawings, in each case in schematic form:

(2) FIG. 1 shows a method according to the invention for controlling an internal combustion engine having a camshaft;

(3) FIG. 2 shows a graphic illustration of a camshaft position profile as a function of the time (continuous line) after the outputting of a stop request with compensation according to a method according to the invention; and

(4) FIG. 3 shows a graphic illustration of a camshaft position profile as a function of the time (continuous line) after the outputting of a stop request without compensation according to the prior art.

DETAILED DESCRIPTION

(5) FIG. 1 shows a method according to the invention for controlling an internal combustion engine with a camshaft and a control device, wherein the phase of the camshaft, in FIG. 2 denoted as G and in FIG. 3 as G, can be adjusted with respect to a crankshaft by means of an electric adjustment device. The method is started in step S1, wherein a stop request denoted in FIG. 2 as A and in FIG. 3 as A, is output to the electric adjustment device by a control device, with the result that the rotational speed of the internal combustion engine is greatly reduced. In step S2, a manipulated variable in the form of a pulse duty factor, denoted in FIG. 2 as B and in FIG. 3 as B, is output by the electric adjustment device, wherein the pulse duty factor counteracts a camshaft torque. Subsequently, in step S3 the direction of rotation of the camshaft is monitored. The detection of the reversal of the direction of rotation usually takes place by means of a sensor but can also additionally or alternatively take place by means of a functional solution in the control device.

(6) If no reversal C of the direction of rotation takes place, monitoring is carried out in step S3 until the internal combustion engine has come to a standstill and the camshaft G is in an ideal starting position, or until a reversal C of the direction of rotation is detected, denoted in FIG. 2 as C and in FIG. 3 as C. It is conceivable here that the camshaft sensor is integrated into the sensor for detecting the reversal of the direction of rotation, or vice versa, wherein the detection of the reversal C of the direction of rotation takes place by means of the control device.

(7) When a reversal C of the direction of rotation of the camshaft G is detected, in the subsequent step S4 an intensity level is calculated, denoted in FIG. 2 as D1, D2 and in FIG. 3 as D1, D2, of this reversal C of the direction of rotation by determining a rotational speed gradient F, wherein a correction signal is output by the control device.

(8) The internal combustion engine preferably comprises a camshaft sensor which is connected to the control device, wherein the camshaft sensor furthermore transmits a phase edge interrupt of a crankshaft encoder wheel as a signal with high chronological resolution to the control device, with the result that the control device can determine the rotational speed gradient on the basis of this signal with high chronological resolution.

(9) Subsequently, in a step S5 the pulse duty factor is corrected as a function of the rotational speed gradient in such a way that the influence of the reversal C of the direction of rotation on the position of the camshaft G can be compensated. It is particularly advantageous here if the influence of the reversal C of the direction of rotation on the pulse duty factor B is stored as a function of the rotational speed gradient as a characteristic diagram in the control device, and the values of the characteristic diagram are added to the pulse duty factor B during the compensation of the reversal C of the direction of rotation.

(10) FIG. 2 shows a schematic graphic illustration of a profile of the position of the camshaft G as a function of the time after the outputting of a stop request A with a compensation B according to the method described above. After the outputting of the stop request A, the rotational speed n is reduced and a pulse duty factor B, which is intended to counteract a camshaft torque, is output. If a reversal of the direction of rotation is detected, as illustrated in the regions C, an intensity level D1 and D2 of this reversal of the direction of rotation is calculated by determining the rotational speed gradient. The pulse duty factor B is corrected as a function of the calculated rotational speed gradient in such a way that the influence of the reversal C of the direction of rotation on the position of the camshaft G is largely compensated, with the result that a virtually ideal starting position of the camshaft can be achieved, as a result of which optimum combustion and therefore the duration of the cold starting process can be shortened.

(11) FIG. 3 illustrates, in contrast to FIG. 2, a method according to the previous prior art. It is clearly apparent here that the pulse duty factor B which is output assumes a continuous profile, and therefore it cannot counteract the reversal C of the direction of rotation and the intensity level D1 and D2 of the reversal C of the direction of rotation of the camshaft. Correspondingly, the position of the camshaft G is adjusted in an uncontrolled and undesired fashion.

(12) The invention is not restricted to the exemplary embodiment described but rather also comprises other identically acting embodiments. The description of the figures serves merely to promote comprehension of the invention.