METHOD FOR OPERATING A DRIVETRAIN OF A MOTOR VEHICLE AND DRIVETRAIN FOR A MOTOR VEHICLE

Abstract

A method for operating a drivetrain of a motor vehicle having at least one centrifugal pendulum, in which the centrifugal pendulum comprises at least one primary part rotatable about an axis of rotation, at least one secondary part movable relative to the primary part, and at least one damping medium by which relative movements are hydraulically dampened between the primary part and the secondary part, wherein at least one temperature of the damping medium is calculated by an electronic calculating device of the drivetrain with the aid of a mathematical model.

Claims

1-10. (canceled)

11. A method for operating a drivetrain of a motor vehicle comprising: at least one centrifugal pendulum, in which the centrifugal pendulum comprises at least one primary part rotatable about an axis of rotation, at least one secondary part movable relative to the primary part, and at least one damping medium by which relative movements are hydraulically dampened between the primary part and the secondary part, wherein at least one temperature of the damping medium is calculated by an electronic calculating device of the drivetrain with the aid of a mathematical model.

12. The method according to claim 11, wherein at least one component of the drivetrain is operated in dependence on the calculated temperature.

13. The method according to claim 11, wherein the drivetrain comprises at least one drive motor designed to drive the motor vehicle, by which at least the primary part is driven and thereby rotated about the axis of rotation.

14. The method according to claim 12, wherein the drive motor is used as the component.

15. The method according to claim 14, wherein a load of the drive motor and/or a rotational speed with which an output shaft of the drive motor is turning is adjusted in dependence on the ascertained temperature.

16. The method according to claim 13, wherein the temperature is calculated with the aid of the mathematical model in dependence on a rotational speed and/or a load of the drive motor.

17. The method according to claim 13, wherein the temperature is calculated with the aid of the mathematical model in dependence on a temperature of a coolant for cooling the drive motor.

18. The method according to claim 11, wherein the temperature is calculated in dependence on a fluid for operating a transmission of the drivetrain.

19. The method according to claim 11, wherein a grease is used as the damping medium.

20. A drivetrain for a motor vehicle, having at least one centrifugal pendulum, which comprises at least one primary part rotatable about an axis of rotation, at least one secondary part movable relative to the primary part, and at least one damping medium by which relative movements are to be hydraulically dampened between the primary part and the secondary part, an electronic calculating device, which is adapted to calculate at least one temperature of the damping medium with the aid of a mathematical model.

21. The method according to claim 12, wherein the drivetrain comprises at least one drive motor designed to drive the motor vehicle, by which at least the primary part is driven and thereby rotated about the axis of rotation.

22. The method according to claim 13, wherein the drive motor is used as the component.

23. The method according to one of claim 14, wherein the temperature is calculated with the aid of the mathematical model in dependence on a rotational speed and/or a load of the drive motor.

24. The method according to one of claim 15, wherein the temperature is calculated with the aid of the mathematical model in dependence on a rotational speed and/or a load of the drive motor.

25. The method according to one of claim 14, wherein the temperature is calculated with the aid of the mathematical model in dependence on a temperature of a coolant for cooling the drive motor.

26. The method according to one of claim 15, wherein the temperature is calculated with the aid of the mathematical model in dependence on a temperature of a coolant for cooling the drive motor.

27. The method according to one of claim 16, wherein the temperature is calculated with the aid of the mathematical model in dependence on a temperature of a coolant for cooling the drive motor.

Description

[0026] Further advantages, features and details of the invention will emerge from the following description of a preferred exemplary embodiment and with the aid of the drawing. The features and combinations of features mentioned above in the specification, as well as the features and combinations of features mentioned below in the description of the figures and/or shown alone in the drawings, may be used not only in the particular indicated combination, but also in other combinations or standing alone, without leaving the scope of the invention.

[0027] The drawing shows:

[0028] FIG. 1 a schematic representation of a drivetrain according to the invention for a motor vehicle; and

[0029] FIG. 2 a flow chart to illustrate a method according to the invention for the operation of the drivetrain.

[0030] In the figures, the same or functionally equal elements are given the same reference numbers.

[0031] FIG. 1 shows in a schematic representation a drivetrain 10 for a motor vehicle, especially for an automobile such as a passenger car. The drivetrain 10 comprises at least one centrifugal pendulum 12, which has at least one primary part 16 rotatable about an axis of rotation 14 and at least one secondary part 18 movable relative to the primary part 16. Moreover, the centrifugal pendulum 12 has at least one damping medium 20, represented especially schematically in FIG. 1, by means of which relative movements between the primary part 16 and the secondary part 18 are to be hydraulically dampened or are dampened, especially during an operation of the drivetrain 10.

[0032] The drivetrain 10 further comprises a drive motor 22, which is configured for example as an internal combustion engine, especially as a reciprocating combustion engine. The drive motor 22 comprises at least one engine casing 24, which is a casing of the drivetrain 10. Furthermore, the drive motor 22 comprises an output shaft 26, configured for example as a crankshaft, which is mounted rotatably on the engine casing 24 and can thereby rotate about the axis of rotation 14 relative to the engine casing 24. In particular, the output shaft 26 rotates about the axis of rotation 14 relative to the engine casing 24 during the aforementioned operation of the drivetrain 10, wherein the drive motor 22 provides at least one torque across the output shaft 26 for the driving of the motor vehicle. The primary part 16 is connected or coupled at least indirectly, especially directly, to the output shaft 26, so that the primary part 16 is driven across the output shaft 26 by the drive motor 22 and in this way is rotated about the axis of rotation 14, especially relative to the engine casing 24.

[0033] In the context of the at least indirect, especially the direct coupling of the primary part 16 to the output shaft 26, it may be provided that the primary part 16 is rotationally fixed at least indirectly, especially directly, to the output shaft 26. It is conceivable for the centrifugal pendulum 12 to comprise the secondary part 18 as a single secondary part and thus precisely one secondary part in the form of the secondary part 18.

[0034] The output shaft 26 is for example a first component of the drivetrain 10. Alternatively or additionally, it is conceivable for the secondary part 18 to be rotationally fixed to a further component, for example in the form of another shaft 28 of the drivetrain 10. Moreover, it is conceivable for the centrifugal pendulum 12 to have multiple secondary parts 18, that is, a plurality of secondary parts. The respective secondary part 18 is for example a pendulum mass, also simply known as a pendulum. Hence, it is conceivable for the centrifugal pendulum 12 to have a plurality of pendulum masses. The secondary part 18 is received for example in a space which is bounded by or formed at least partly, especially at least predominantly or entirely by the primary part 16. For example, the damping medium 20 is also received in the space. Moreover, it is conceivable for the primary part 16 to be rotationally fixed to the further component in the form of the further shaft 28. On the whole, it can be seen for example that the shaft 28 is driven or can be driven across the centrifugal pendulum 12 by the output shaft 26 and thus by the drive motor 22. The shaft 28, for example, is a transmission input shaft of a transmission 30 of the drivetrain 10 or is rotationally fixed at least indirectly, especially directly, to the transmission input shaft. Hence, for example, the torque provided by the drive motor 22 across the output shaft 26 can be transferred across the centrifugal pendulum 12 to the shaft 28 and be channeled across the shaft 28 to the transmission 30.

[0035] The transmission 30 is for example an automatic transmission and it may be designed in particular as a converter automatic transmission. Alternatively or additionally, the transmission 30 is designed as a hydraulically operated transmission, so that the transmission 30 can be operated, in particular activated, by means of a fluid, especially one formed as a liquid, also known as transmission fluid. In particular, the transmission fluid is used in order to activate or shift at least one or more shifting elements of the transmission 30 and in particular to move them relative to a transmission casing 32 of the transmission 30.

[0036] Now, if a relative movement occurs for example between the primary part 16 and the secondary part 18, where this relative movement may be a relative rotation between the primary part 16 and the secondary part 18 occurring in particular about the axis of rotation 14, at least a portion of the damping medium 20 will flow through at least one gap from a first chamber to a second chamber, for example, the chambers being for example components of the respective receiving space. Thanks to this flow of the damping medium 20, the relative movement between the primary part 16 and the secondary part 18 is dampened, for example. In this way, radial vibrations of the at least one secondary part 18 can be dampened. On the whole, it is conceivable that rotary or torsional vibrations of the output shaft 26 will be dampened by means of the centrifugal pendulum 12. The damping medium 20 will have a dampening function, by means of which the primary part 16 and the secondary part 18 or their relative movements with respect to each other are dampened.

[0037] The primary part 16 and the secondary part 18 can move, in particular rotate, relative to each other in particular between two end positions, but not beyond the end positions. The end positions are defined or formed for example by respective end stops.

[0038] Now, if the damping medium 20 has an especially low temperature, resulting for example from low outdoor temperatures or ambient temperatures, as compared to higher temperatures, it may happen that the secondary part 18 during the course of the relative movements between the primary part 16 and the secondary part 18 will knock hard against the respective end stop, unless appropriate countermeasures are taken. Unwanted noise may result from this hard knocking, which can be acoustically perceived by passengers of the motor vehicle.

[0039] Now, in order to avoid the occurrence of such noises and thus realize an especially low-noise and at the same time an especially efficient operation of the drivetrain 10, the drivetrain 10 comprises an electronic calculating device 34, shown especially schematically in FIG. 1, which is adapted to calculate with the aid of a mathematical model at least one temperature of the damping medium 20. In other words, a method is provided for operating the drivetrain 10, wherein the electronic calculating device 34 of the drivetrain 10 is used to calculate at least one temperature of the damping medium 20 with the aid of the mathematical model. It is preferably provided that there is no detection or measurement of the temperature of the damping medium 20 by a temperature sensor. This embodiment is based on the fact that the centrifugal pendulum 12 is a rotary system, because at least the primary part 16 or the centrifugal pendulum 12 as a whole is driven by the output shaft 26 and thereby turned about the axis of rotation 14, for which the detection of the temperature by means of a temperature sensor is very costly, if not impossible, and this is preferably avoided.

[0040] In particular, it is possible with the method to operate at least one component and at least the drive motor 22 for example in dependence on the calculated temperature, especially to control or regulate it. This is done preferably by means of the electronic calculating device 34.

[0041] FIG. 2 shows a flow chart explaining the method more closely. The method involves, for example, a block 36, which comprises the mathematical model for example. In the block 36, the temperature is calculated. For example, the centrifugal pendulum 12 is a dual mass flywheel (ZMS), so that the temperature is a ZMS temperature, for example.

[0042] For example, it is illustrated by an arrow 38 that the temperature of the damping medium 20 is calculated with the aid of the mathematical model in dependence on a rotational speed and/or a load of the drive motor 22. In other words, a heat and/or temperature input in the damping medium 20 is calculated in terms of motor rotational speed and load or engine torque, for example. It is illustrated by a double arrow 40 that the temperature of the damping medium 20 is calculated with the aid of the mathematical model in dependence on a temperature of a coolant for cooling the drive motor 22, especially one in the form of a liquid. In other words, a heat or temperature input and/or a temperature or heat output occurs through the coolant, also known as the motor coolant. The temperature of the damping medium 20 is calculated in dependence on the temperature input in terms of the motor rotational speed and the engine torque as well as the input or output through the coolant. It is illustrated by the double arrow 40 that the damping medium 20 can be heated or also cooled by means of the coolant, depending on the operating state of the drivetrain 10, which is taken into consideration by the method.

[0043] It is illustrated by an arrow 42 that the temperature of the damping medium 20 is calculated in dependence on revolutions of the drive motor 22, especially the output shaft 26, and in dependence on a current model temperature. For example, a weighting is done in terms of the engine torque, as illustrated in FIG. 2 by an arrow 44. The heat or temperature input in terms of motor revolutions and current model temperature is filtered by means of a filter 46 and then taken to the block 36. In particular, consideration is given to the fact that the thicker the damping medium 20, the higher the heat input.

[0044] As the starting value for the temperature of the damping medium 20 there is used for example a temperature of the transmission fluid during activated ignition of the motor vehicle. It is illustrated by a double arrow 48 that the temperature of the damping medium 20 is calculated with the aid of the mathematical model in dependence on the transmission fluid for the operation of the transmission 30. Depending on the operating state of the drivetrain 10, the damping medium 20 can be cooled or heated by means of the transmission fluid, so that depending on the operating state of the drivetrain 10 a heat or temperature input in the damping medium 20 or a temperature or heat output from the damping medium 20 is accomplished by means of the transmission fluid.

[0045] On the whole, it will be seen that the temperature of the damping medium 20 is calculated for example in dependence on the load of the drive motor 22, of the rotational speed with which the output shaft 26 is turning, and in dependence on the transmission 30, especially in dependence on the transmission fluid or in dependence on the temperature of the transmission fluid.

[0046] Preferably, a grease is used as the damping medium 20, with which the radial vibrations can be dampened especially advantageously. Moreover, it is preferably provided that the load and/or the rotational speed of the drive motor 22 is adjusted in particular in dependence on the calculated temperature. In this way, for example, it is possible to adjust a higher rotational speed at low temperatures of the damping medium than at higher temperatures, in order to thereby prevent the aforementioned knocking. However, operating states with such an elevated motor rotational speed can now be kept especially short, because the temperature of the damping medium is calculated especially precisely, so that an excessive energy consumption, especially a fuel consumption, can be avoided. Consequently, an especially low-noise and efficient operation can be produced.