METHOD FOR ASCERTAINING A TORQUE CURVE OF AN INTERNAL COMBUSTION ENGINE OF A HYBRID POWERTRAIN, AND HYBRID POWERTRAIN

Abstract

A method is provided for ascertaining a torque curve of a hybrid powertrain including a first sub-powertrain an internal combustion engine, and a second sub-powertrain, which is separated from the first sub-powertrain by a torsional elasticity and has an electric machine with a rotor (10). A rotational characteristic value of the first sub-powertrain is detected via a sensor arranged on the torsional elasticity. A rotational characteristic value of the rotor is detected via a device engaged with the rotor. An irregularity in operation of the internal combustion engine is determined based on at least one of the rotational characteristic value of the first sub-powertrain or the rotational characteristic value of the rotor. The electric machine is controlled based on the irregularity m operation.

Claims

1. A method for ascertaining a torque curve of a hybrid powertrain including a first sub-powertrain having, an internal combustion engine and a second sub-powertrain, which is separated from the first sub-powertrain by a torsional elasticity and has an electric machine with a rotor, the method comprising: detecting a rotational characteristic value of the first sub-powertrain via a sensor arranged on the torsional elasticity; detecting a rotational characteristic value of the rotor via a device engaged with the rotor; and determining an irregularity in operation of the internal combustion engine based on at least one of the rotational characteristic value of the first sub-powertrain or the rotational characteristic value of the rotor; and controlling the electric machine based on the irregularity in operation.

2. The method according to claim 1, further comprising: detecting the rotational characteristic value of the first sub-powertrain for at least two consecutive ignition curves in different cylinders of the internal combustion engine; and determining the irregularity in operation of the internal combustion engine based on a difference between the rotational characteristic values of the first sub-powertrain for the corresponding the ignition curves exceeding a threshold.

3. The method according to claim 1, further comprising: detecting the rotational characteristic value of the first sub-powertrain for an ignition curve of at cylinder; and determining the irregularity in operations of the internal combustion engine based on a difference between the rotational characteristic value of the first sub-powertrain for the ignition curve of the cylinder and a stored ignition curve of the cylinder.

4. The method according to claim 1, further comprising determining the irregularity in operation of the internal combustion engine based on a difference between the rotational characteristic value of the first sub-powertrain and the rotational characteristic value of the rotor, wherein a torque provided by the internal combustion engine is constant.

5. The method according to claim 2, further comprising determining the difference via a state estimator.

6. The method according to claim 1, wherein the rotational characteristic value of the first sub-powertrain and the rotational characteristic value of the rotor corresponding to a same rotational characteristic, the rotational characteristic being one as a rotational revolutions, a rotational speeds, a rotational acceleration, or a rotational angles.

7. The method according to claim 1, further comprising determining at least one of applied kinetic energy, potential energy, transmitted torques, applied speeds, or rotational accelerations in at least one of the sub-powertrains or the torsional elasticity based on the rotational characteristic values in the first sub-powertrain and the rotational characteristic value in the rotor.

8. The method according to claim 1, wherein the device is a sensor configured to control electronic communication of the electric machine.

9. The method according to claim 1, wherein the device is a state observer configured to control the electric machine based on evaluating electrical variables in a stator of the electric machine.

10. A hybrid powertrain, comprising: a first sub-powertrain, including an internal combustion engine having a crankshaft; a second sub-powertrain including an electric machine having a rotor; a torsional elasticity arranged between the first sub-powertrain and the second sub-powertrain, the torsional elasticity being connected to crankshaft and the rotor; a sensor arranged on the torsional elasticity and configured to detect a rotational characteristic value of the crankshaft; a device engaged with the rotor and configured to detect a rotational characteristic value of the rotor; and a controller in communication in with the sensor and the device, the controller being configured to: receive the rotational characteristic value of the crankshaft from the sensor; receive the rotational characteristic value of the rotor from the device; determine an irregularity in operation of the internal combustion engine based on at least one of the rotational characteristic value of the crankshaft or the rotational characteristic value of the rotor; and control the electric machine based on the irregularity in operation.

11. The method according to claim 1, further comprising: detecting the rotational characteristic value of the first sub-powertrain in one cylinder of the internal combustion engine; after a period of time, detecting a subsequent rotational characteristic value of the first sub-powertrain in the one cylinder; and determining the irregularity in operation of the internal combustion engine based on a difference between the rotational characteristic value and the subsequent rotational characteristic value exceeding a threshold.

12. The method according to claim 1, wherein the irregularity in operation of the internal combustion engine is one of a misfire, a valve misalignment, or an insufficient fuel injection.

13. The method according to claim 3, wherein the stored ignition curve is adapted based on control variables of the internal combustion engine.

14. The hybrid powertrain according to claim 10, wherein the controller is further configured to: receive the rotational characteristic value of the first sub-powertrain for at least two consecutive ignition curves in different cylinders of the internal combustion engine; and determine the irregularity in operation of the internal combustion engine based on a difference between the rotational characteristic values of the first sub-powertrain for the corresponding the ignition curves exceeding a threshold.

15. The hybrid powertrain according to claim 10, wherein the controller is further configured to: receive the rotational characteristic value of the first sub-powertrain for an ignition curve, of a cylinder; and determine the irregularity in operation of the internal combustion engine based on a difference between the rotational characteristic value of the first sub-powertrain for the ignition curve of the cylinder and a stored ignition curve of the cylinder.

16. The hybrid powertrain according to claim 15, wherein the stored ignition curve is adapted based on control variables of the internal combustion engine.

17. The hybrid powertrain according to claim 10, wherein the controller is further configured to: receive the rotational characteristic value of the first sub-powertrain in one cylinder of the internal combustion engine; after a period of time, receive a subsequent rotational characteristic value of the first sub powertrain in the one cylinder; and determine the irregularity in operation of the internal combustion engine based on a difference between the rotational characteristic value and the subsequent rotational characteristic value exceeding a threshold.

18. The hybrid powertrain according to claim 10, wherein the controller is further configured to determine the irregularity in operation of the internal combustion engine based on a difference between the rotational characteristic value of the first sub-powertrain and the rotational characteristic value of the rotor, wherein a torque provided by the internal combustion engine is constant.

19. The hybrid powertrain according to claim 10, wherein the irregularity in operation of the internal combustion engine is one of a misfire, a valve misalignment, or an insufficient fuel injection.

20. The hybrid powertrain according to claim 10, wherein the rotational characteristic value of the first sub-powertrain and the rotational characteristic value of the rotor correspond to a same rotational characteristic, and wherein the rotational characteristic is one of a rotational revolution, a rotational speed, a rotational acceleration, or a rotational angle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The disclosure is explained in more detail with reference to the exemplary embodiment in the single FIGURE. This shows a hybrid powertrain in a schematic representation.

DETAILED DESCRIPTION

[0021] A hybrid powertrain 1 shown schematically contains sub-powertrains 2, 3. The sub-powertrain 2 contains an internal combustion engine 4, here with four cylinders 5, and the crankshaft 6 driven in rotation thereby. A torsional elasticity 7, here a torsional vibration damper such as a dual-mass flywheel, is accommodated on the crankshaft 6, which separates the first sub-powertrain 2 from the second sub-powertrain 3. A device 8 for detecting rotational characteristic values of the crankshaft 6 and thus the control of the internal combustion engine 4 is assigned to the first sub-powertrain 2. For this purpose, a sensor ring is arranged on an input part of the torsional elasticity 7, from the increments of which are detected by a sensor, and corresponding rotational characteristic values, for example the rotational speed, the rotational angle, the rotational acceleration and/or the like, are ascertained from these.

[0022] An output part of the torsional elasticity 7 is connected to a rotor 10 of an electric machine 9 in a rotationally locked manner. The electric machine 9 is assigned to the second sub-powertrain 3. The electric machine 9 is controlled by means of a device 11 for ascertaining rotational characteristic values. For example, the device 11 can be formed from one or more Hall sensors, which detect increments from a transmitter device arranged on the rotor 10 or a component connected to it in a rotationally locked manner and use these to ascertain the rotational characteristic values of the rotor 10 in order to use them to control the commutation of the electric machine 9 and to ascertain the position of the rotor 10 as a function of time. Alternatively, the electric machine 9 can be controlled without sensors by means of the device 11 in that the electrical variables of a stator 12 are detected and evaluated by means of a state observer.

[0023] In order to quickly and reliably ascertain misfiring of the internal combustion engine 4 in the proposed method, the signals from the devices 8, 11 are jointly evaluated by a controller 13. In this way, the rotational characteristics of the sub-powertrains 2, 3 and thus, with knowledge or modeling of the system properties of the hybrid powertrain 1, influencing variables on the sub-powertrains 2, 3 and the torsional elasticity 7, such as applied torques, rotational acceleration, mass moment of inertia and the like, can be determined or at least estimated.

[0024] For example, by comparing the torsional characteristics of the devices 8, 11, the effect of ignition curves before and after the torsional elasticity 7 can be detected and the influence of misfiring on the two sub-powertrains 2, 3 can thereby be detected. For example, the shapes of successive ignition curves of the cylinders 5 can be compared with one another and misfiring can be detected in real time from a change in the shapes. Alternatively or additionally, by observing the rotational angle between the crankshaft 6 and the rotor 10 under otherwise constant conditions, such as without engine intervention in the internal combustion engine 4 and without changing the control of the electric machine 9, misfires can occur due to changes in the rotational angle or changes in the course of the rotational angle during a working stroke or a change in one or more compressed values can be detected, for example, from the course of the rotational angle.

LIST OF REFERENCE SYMBOLS

[0025] 1 Hybrid powertrain [0026] 2 Sub-powertrain [0027] 3 Sub-powertrain [0028] 4 Internal combustion engine [0029] 5 Cylinder [0030] 6 Crankshaft [0031] 7 Torsional elasticity [0032] 8 Device [0033] 9 Electric machine [0034] 10 Rotor [0035] 11 Device [0036] 12 Stator [0037] 13 Controller