DE102022105669A1 - Method for controlling a drive torque during a load change process - Google Patents

Abstract

The invention relates to a method (26) for controlling a drive torque (28) which is provided by a drive element (14) of a drive train (10) and can be transmitted to an output element (20) via a torque transmission element (18), the drive torque (28) during a load change process (32), in which a reversal of a torque transmission direction of a transmission torque (30), which can be transmitted between the drive element (14) and the driven element (20) and is applied to the torque transmission element (18), takes place and a load change time as a zero crossing of the transmission torque (30), is controlled by the drive torque (28) during the load change process (32) as a function of a dynamic transmission behavior of the torque transmission path that includes the torque transmission element (18), which characterizes the relationship between the drive torque (28) and the transmission torque (30). (17 ) is set between the drive element (14) and the driven element (20).

Description

The invention relates to a method for controlling a drive torque during a load change process.

In DE 10 2010 014 193 A1 a method is described in which, in order to reduce loads during a load change process, a transmission is braced by engaging gears.

In DE 10 2006 010 934 A1 a method is described in which a clutch is actuated during a load change process.

The object of the present invention is to carry out the load change process more gently and less noticeably. The loads in the drive train that occur as a result of the torque changes during the load change process are to be reduced.

At least one of these objects is achieved by a method for controlling a drive torque provided by a drive element of a drive train with the features of claim 1. As a result, the load change process can be carried out more gently and less noticeably. The loads in the drive train that occur as a result of the torque changes during the load change process can be reduced. The driven element can be operated more reliably.

The powertrain may be located in a vehicle. The vehicle may be a hybrid vehicle or an electric vehicle. The drive element can be an electric motor. The torque transmission element can be a transmission and/or a clutch. The output element can be a transmission output shaft, a differential gear, at least one vehicle axle or at least one vehicle wheel.

At the time of the load change, the transmission torque is preferably zero. The load change time can deviate from a zero crossing of the drive torque. The deviation can depend on the dynamic transmission behavior. In a load change process starting from a traction operation, in which the drive torque is transmitted to the output element, to a coasting operation with reverse torque transmission direction, the load change time can be after the zero crossing of the drive torque.

During the load change process, a change of intention can occur, which reverses or interrupts the previously desired reversal of the torque transmission direction. For example, such a change of mind may occur when the accelerator pedal changes from an actuated to an unactuated position and shortly thereafter back to an actuated position.

In a preferred embodiment of the invention, it is advantageous if the drive torque is changed in stages during the load change process before the load change time in torque switching stages, in that the drive torque is changed from a first torque value to at least a second torque value and from there to a third torque value. The absolute value of the torque difference between the first torque value and the second torque value and/or between the second torque value and the third torque value can be half the first torque value.

In a preferred embodiment of the invention, it is provided that the drive torque is changed step by step during the load change process after the load change time by changing the drive torque in torque switching stages, starting from a fourth torque value to at least a fifth torque value and starting from there to a sixth torque value. The absolute value of the torque difference between the fifth torque value and the fourth torque value and/or between the sixth torque value and the fifth torque value can be half the sixth torque value.

In a preferred embodiment of the invention, it is provided that the drive torque is changed in more than two torque switching stages. The number of torque shift stages may depend on an initial drive torque.

A preferred embodiment of the invention is advantageous in which a time interval between at least two torque switching stages is set as a function of the dynamic transmission behavior. As a result, the zero crossing of the drive torque can be brought closer to the load change time of the transmission torque.

In a special embodiment of the invention, it is advantageous if the dynamic transmission behavior can be described by a period and the time interval is set as a function of the period. As a result, the time delay occurring in the transmission torque compared to the drive torque with a dynamic change in the Drive torque are taken into account. The period can depend on mass inertia and torsional rigidity in the torque transmission path.

In a specific embodiment of the invention, it is advantageous if the time interval is set as half a period. As a result, the zero crossing of the drive torque can be adjusted to the load change time of the transmission torque.

In a preferred embodiment of the invention, it is provided that the drive torque during the load change process is changed with a fixed torque gradient in a changeover time window that includes the time of the load change. The torque gradient may vary within a predetermined range during the switching time window. The torque gradient can also be constant during the switching time window.

Instead of the switching time window, a torque window including the zero crossing of the transmission torque can also be assumed, which is defined by at least two predefined torque values of the drive torque. Once the drive torque is within the torque window, the drive torque can be varied with a specified torque gradient. The torque gradient can be set constant. The torque window can be specified by the switching time window and vice versa.

In a specific embodiment of the invention, it is advantageous if the drive torque is set constant from the start of the changeover time window within a waiting time and/or after the end of the changeover time window within a waiting time. As a result, the load change process can be carried out gently at the time of the load change.

In an advantageous embodiment of the invention, it is provided that the load change time is detected as a function of a speed change of the drive element. The start of the switchover time window can also be detected via the change in speed. An end of the switching time window can also be detected via the speed change.

Further advantages and advantageous configurations of the invention result from the description of the figures and the illustrations.

character list

• 1: Einen Antriebsstrang zur Anwendung eines Verfahrens zur Steuerung eines Antriebsdrehmoments in einer speziellen Ausführungsform der Erfindung.
• 2: Ein Diagramm bei Anwendung eines Verfahrens zur Steuerung eines Antriebsdrehmoments in einer weiteren speziellen Ausführungsform der Erfindung.
• 3: Einen Teilablauf eines Verfahrens zur Steuerung eines Antriebsdrehmoments in einer weiteren speziellen Ausführungsform der Erfindung.

The invention is described in detail below with reference to the figures. They show in detail:

• 1 : A power train for applying a method for controlling a driving torque in a specific embodiment of the invention.
• 2 : A diagram when applying a method for controlling a driving torque in another specific embodiment of the invention.
• 3 : A partial flow of a method for controlling a driving torque in a further specific embodiment of the invention.

1 FIG. 12 shows a power train for applying a method for controlling a driving torque in a specific embodiment of the invention. The drive train 10 is arranged, for example, in a vehicle 12 and has a drive element 14 which is preferably designed as an electric motor 16 . The drive member 14 may provide drive torque to drive the vehicle 12 . Drive torque is transferred to an output member 20 via a torque transfer path 17 including a torque transfer member 18 for driving the vehicle 12 . The torque transmission element 18 is preferably designed as a transmission 22 and the output element 20 as a vehicle wheel 24 .

If the vehicle 12 is driven by the drive element 14 , the drive torque is transmitted as a traction torque from the drive element 14 via the torque transmission element 18 as a transmission torque to the output element 20 . During a load change process, there is a switchover from the traction torque to a thrust torque, which is transmitted from the output element 20 via the torque transmission element 18 as the transmission torque 30 to the drive element 14 . A load change in the opposite direction, i.e. from a shearing moment to a pulling moment, is also possible.

During the load change process, a torque transmission direction of the transmission torque that is applied to the torque transmission element 18 is reversed.

2 Fig. 12 shows a diagram when using a method for controlling a driving torque in another specific embodiment of the invention. The method 26 for control of a drive torque 28 of the drive element can be carried out during operation of the vehicle and is to be explained here using a diagram representing the torque M as a function of the time t. The vehicle is driven, for example, with a constant drive torque 28 as traction torque up to time t1. The transmission torque 30 corresponds to the drive torque 28 up to the point in time t1. From the point in time t1, the load change process 32 is initiated, for example because the vehicle is to reduce its speed. The load change process 32 is completed at the point in time t4, from which the drive torque 28 and the transmission torque 30 is an overrun torque. The transmission torque 30 has thus reversed the torque transmission direction and passed through zero at a load change point in time t3.

If the drive torque 28 is reduced from the beginning of the load change process 32 at time t1, for example by a change in the acceleration specification 34, which corresponds to an accelerator pedal position of the vehicle, for example, the transmission torque 30 follows this reduction with a time delay due to the dynamics of the changing drive torque 28 and the dynamic transmission behavior of the torque transmission path between the drive element and the driven element, which includes the torque transmission element.

In method 26, at the start of load change process 32 at point in time t1, drive torque 28 is set as a function of the dynamic transmission behavior of the torque transmission path. As a result, the load change process 32 can be carried out more gently and quietly. The drive torque 28 is gradually changed at the beginning of the load change process 32 at the time t1 in torque switching stages 36 by the drive torque 28 starting from a first torque value M1 to a second torque value M2 at the time t1 and proceeding therefrom at the time t2 to a third torque value M3, which is still a tensile moment, is changed.

The drive torque 28 is then changed from time t2 during the load change process 32 in a changeover time window 38 including the load change time t3 with a fixed torque gradient 40 in order to carry out the changeover of the torque transmission direction at the load change time t3 as gently as possible. This change can be carried out as a function of time in relation to switchover time window 38 and/or as a function of torque in relation to a torque window 42 forming switchover time window 38 .

The torque gradient 40 is set constant within the switching time window 38 between the time t2 and the time t4, between which the load change time t3 is involved. Correspondingly, the torque gradient 40 is set constant within the torque window 42 between the third torque value M3 and the fourth torque value M4. After the end of the changeover time window 38 at the point in time t4, the drive torque 28 is constantly set to a fourth torque value M4 within a waiting time 44, which extends from the point in time t4 to the point in time t5.

The drive torque 28 is then gradually changed during the load change process 32 after the load change time t3, here specifically after the time t5, by the drive torque 28 in torque switching stages 36 starting at the time t5 starting from the fourth torque value M4 to a fifth torque value M5 and starting from there to the Time t6 is changed to a sixth torque value M6.

The drive torque 28 is adjusted by the torque switching stages 36 in order to likewise have a zero crossing at the time of the load change at which the transmission torque 30 is zero. The drive torque 28 is adjusted as a function of the dynamic transmission behavior of the torque transmission path by taking into account a period T that describes the dynamic transmission behavior and characterizes the time profile of the transmission torque 30 as a step response to a reduction 48 in the drive torque 28 .

During the load change process 32, two torque shift stages 36 are preferably set before the load change time t3, and two torque shift stages 36 are also set after the load change time t3. The time interval between the torque switching stage 36 at time t1 and the torque switching stage 36 at time t2 is preferably half a period T/2. This allows the zero crossing of the drive torque 28 and the transfer torque 30 to match.

Even after the load change process 32, a time interval between the torque switching stage 36 at the point in time t5 and the torque switching stage 36 at the point in time t6 is preferably set to half a period T/2.

The amount of the second torque value M2 corresponds in particular to half of the first torque value M1. The absolute value of the fifth torque value M5 corresponds in particular to half of the sixth torque value M6. This setting of the drive torque 28 enables a two-stage adjustment of the drive torque 28 depending on the dynamic transmission behavior of the torque transmission line.

3 shows a partial sequence of a method for controlling a drive torque in a further specific embodiment of the invention. The partial sequence of the method 26 describes a possible procedure for setting the drive torque in the changeover time window including the time of the load change. In a first step 46, it is checked whether the applied drive torque is in the torque window, in particular between the third torque value and the fourth torque value. If this is not the case, the drive torque to be set is reduced 48, for example by using the torque stages.

If, on the other hand, the drive torque is in the torque window, for example between the third and fourth torque value, a query 50 is made about a present beginning or an end of the switchover time window. If the changeover time window is already effective, then the torque gradient of the drive torque is limited 52 and the drive torque is preferably set to be constant.

If, on the other hand, the switchover time window begins or ends, a check 54 takes place as to whether a waiting time is to be applied. If the waiting time is effective, then the drive torque is set 56, during which the drive torque is set to be constant. When the waiting time is over, the limitation of the drive torque is canceled 58 .

reference list

10

powertrain

12

vehicle

14

drive element

16

electric motor

17

torque transmission line

18

torque transmission element

20

output element

22

transmission

24

vehicle wheel

26

procedure

28

drive torque

30

transmission torque

32

load change process

34

Acceleration target

36

torque switching stage

38

switching time window

40

torque gradient

42

torque window

44

waiting period

46

Step

48

reduction

50

query

52

limitation

54

examination

56

Attitude

58

cancellation

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102010014193 A1 [0002]
• DE 102006010934 A1 [0003]

Claims (10)

Method (26) for controlling a drive torque (28) provided by a drive element (14) of a drive train (10) and which can be transmitted via a torque transmission element (18) to an output element (20), the drive torque (28) during a load change process ( 32), in which there is a reversal of a torque transmission direction of a transmission torque (30), which can be transmitted between the drive element (14) and the driven element (20) and is applied to the torque transmission element (18), and which has a load change time (t3) as the zero crossing of the Includes transmission torque (30), is controlled by the drive torque (28) during the load change process (32) depending on a relationship between the drive torque (28) and the transmission torque (30) characterizing dynamic transmission behavior of the torque transmission element (18) including torque transmission path ( 17) between the drive selement (14) and the output element (20) is set. Method (26) according to claim 1 , characterized in that the drive torque (28) during the load change process (32) before the load change time (t3) is changed stepwise in torque switching stages (36) by the drive torque (28) starting from a first torque value (M1) to at least a second torque value (M2) and based thereon to a third torque value (M3). Method (26) according to claim 1 or 2 , characterized in that the drive torque (28) during the load change process (32) is gradually changed after the load change time (t3) by the drive torque (28) in torque switching stages (36) starting from a fourth torque value (M4) to at least a fifth torque value (M5) and based thereon to a sixth torque value (M6). Method (26) according to claim 2 or 3 , characterized in that the change in the drive torque (28) is carried out in more than two torque switching stages (36). Method (26) according to any one of claims 2 until 4 , characterized in that a time interval between at least two torque switching stages (36) is set depending on the dynamic transmission behavior. Method (26) according to claim 5 , characterized in that the dynamic transmission behavior can be described by a period (T) and the time interval is set as a function of the period (T). Method (26) according to claim 6 , characterized in that the time interval is set as half a period (T/2). Method (26) according to one of the preceding claims, characterized in that the drive torque (28) during the load change process (32) is changed with a fixed torque gradient (40) in a switchover time window (38) including the load change time (t3). Method (26) according to claim 8 , characterized in that from the beginning of the switching time window (38) within a waiting time (44) and / or after the end of the switching time window (38) within a waiting time (44), the drive torque (28) is set constant. Method (26) according to one of the preceding claims, characterized in that the load change time (t3) is detected as a function of a speed change of the drive element (14).

Images