Noise reduction in electric vehicle drive trains.

Abstract

To improve control of an electric drive machine of a motor vehicle, the rotor shaft of the electric drive machine being coupled to an output shaft of the motor vehicle by means of a gear transmission. [Solution] A method for controlling an electric drive machine of a motor vehicle, in which a rotor shaft of the electric drive machine is connected to an output shaft of the motor vehicle by means of a gear transmission, in which, during a load change L of the drive machine, before a flank change F of the gear transmission, torque shocks S, S2 of the drive machine are set in order to adapt the common rotational motion of the gears of the gear transmission.

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE The present invention relates to a method and means for controlling an electric drive machine for a motor vehicle, where the rotor shaft of the electric drive machine is coupled to the output shaft of the motor vehicle by means of a gear transmission. [Background technology]

[0002] Gear transmissions, which are often directly coupled to electric drive machines as reduction stages, are known to produce rattling noises during load changes, leading to unpleasant structure-borne noise impulses at moment zero crossings of the drive machine, for example during shunting operations or during traction / thrust alternations.

[0003] Known methods attempt to reduce this impulse as little as possible without affecting the driveability and, in the best case, without it being perceptible by the vehicle occupants, by means of moment interventions which are introduced at and just before the flank changeover and which are parameterized to reduce the moment gradient.

[0004] However, this only has a small effect on the cause, i.e. the excitation of noise, and the application time of the intervention is strictly limited, especially if the perception of the intervention by the driver is to be avoided, so that the known method additionally requires extensive secondary measures in the underbody protection by means of foam parts or other encapsulation measures. Summary of the Invention [Problem to be solved by the invention]

[0005] Against this background, the object of the present invention is to improve the control of an electric drive machine of a motor vehicle, the rotor shaft of which is coupled to the output shaft of the motor vehicle by means of a gear transmission. [Means for solving the problem]

[0006] Each independent claim specifies the object which is solved by its features. The dependent claims relate to advantageous developments of the invention.

[0007] According to one aspect, a method of controlling an electric drive machine of a motor vehicle is disclosed, where a rotor shaft or a motor output shaft of the drive machine coupled to the rotor shaft for torque transmission is coupled to an output shaft of the motor vehicle by means of a gear transmission. Typically, the rotor shaft or motor output shaft is loaded with a fluctuating motor output torque, which acts to accelerate, brake or not affect the change in rotational motion in idling operation. Typically, the output shaft is directly or indirectly coupled to a drive gear of the motor vehicle and is therefore loaded with a fluctuating driving torque depending on the driving operation.

[0008] During a load change of the drive machine, a torque shock of the drive machine is temporarily set up before the flank change of the gear transmission for adaptation (in particular deceleration or acceleration) of the in particular common rotational movement of the gears of the gear transmission, i.e. according to one embodiment, the torque shock is controlled and / or completely terminated before the flank change.

[0009] The torque shock can be understood here in particular to be based on the output torque profile over time, which is in particular set in the first place before, during and after the load change.

[0010] That is to say, in particular, the torque shock, i.e. the torque intervention in the sense of a deviation from the torque profile of the drive machine that was set due to the load change, is selected so that the peripheral speeds of the two meshing gears are adapted and / or the relative peripheral speeds of the two meshing gears are reduced.

[0011] The type of adaptation of the rotational speed depends in particular on the type of load change; for load changes on the thrust flank, a decelerating torque shock is set, and for load changes on the traction flank, an accelerating torque shock is set.

[0012] It is thereby possible to achieve that the flanks of both gears, which abut against each other due to tooth play after the flank change, collide at a smaller relative speed. Despite the relative speed of the flanks colliding against each other due to play that occurs during the flank change, the impact is smaller due to the reduced / increased absolute peripheral speed and thus the resulting noise is also smaller. This makes it possible to avoid poor perceived quality of the transmission due to loud noise (often perceived as "clicking").

[0013] Load change can be understood here in the narrow sense as a zero crossing of the output torque of the drive machine, which zero crossing is based on the driving behavior, for example when switching between forward and reverse gears or vice versa or when switching from acceleration to braking or vice versa. However, in another sense, the entire transition of the load change intention or the perception of the load change situation up until the end of the flank change is also intended here. Considered abstractly, there are two types of load change in the sense here: load change on the traction flank and load change on the thrust flank.

[0014] Flank alternation of two gears meshing with one another is to be understood here in particular as the transfer of contact between the gears from the flank of the first meshing tooth of one of the gears to the flank of the subsequently meshing tooth. As a rule, said flank alternation is accompanied by play, so that in the event of a torque fluctuation on one of the gear shafts, even the involute teeth can cause audible collisions when a new flank contact is established, which occur due to the additional relative speed when going through the play at the different torques occurring. Such collisions are perceptible in particular at relatively low rotational speeds (of the drive and thus of the shaft and gears).

[0015] A common rotational movement of two engaged gears is to be understood here in particular as a rotational movement in which the two gears run dependent on one another, i.e. in contact with one another, in particular when no flank exchange takes place, during which torque shocks can adapt the rotational movement of the two gears (and thus the shaft) without causing a relative movement of the two gears relative to one another.

[0016] According to another aspect, an apparatus for controlling an electric drive machine of a motor vehicle is disclosed, the apparatus being configured to perform a method according to one aspect of the invention, the electric drive machine having a rotor shaft coupled to an output shaft of the motor vehicle by means of a gear transmission.

[0017] The invention is based on the idea of ​​introducing a formable torque transition, in particular in the sense of a torque shock for braking or accelerating the rotor of the electric drive machine, as a deviation into the moment transition before the flank change, which moment transition can be adapted in particular in its magnitude, its duration and / or a time interval (before the flank change) to the flank change and can be triggered, for example, by a moment threshold and / or a moment gradient. The torque shock reduces the impact velocity of the transmission shaft when the flank changes due to the load change. The reduced impact velocity contributes to a significantly smaller structure-borne sound impulse and thus to less noise.

[0018] According to one embodiment, the torque shock has a torque gradient transition, in particular with at least two sign changes between the shock start and the shock end, in particular when considered with the output torque transitions of the immediately preceding and subsequent adjacent drive machines.

[0019] This allows relatively strong interventions in the output torque curve of the drive machine within short, optimally imperceptible times for the driver or other passengers or bystanders.

[0020] According to one embodiment, a decelerating torque shock occurs during a load change on the thrust flank and / or an accelerating torque shock occurs during a load change on the traction flank.

[0021] This makes it possible to achieve noise reduction in both possible types of load changes.

[0022] According to one configuration, the torque shock ends before the start of flank change, in particular before the end of roller contact on the "old" flank, and thus before the motion of both gears reaches the idle phase, during which they are independent of each other.

[0023] This makes it possible to accurately predict the effect of the torque shock, since no intervention takes place in the play phase; the required allocation (adjustment) of the torque shock is possible.

[0024] According to one configuration, the torque shock is determined by the shock intensity, i.e. the deviation of the shock torque from the normal load change torque for the particular operating case. In particular, the shock intensity, i.e. the amplitude (magnitude) of the shock is 3-15 Nm, in particular 5-10 Nm.

[0025] A torque shock of this magnitude is typically not perceived as an undesirable deviation from the desired driving behavior of the motor vehicle in turbulent operation.

[0026] According to one configuration, the torque shock is determined by the shock duration, i.e. the duration from the first to the last deviation of the shock torque from the normal load change torque for the particular operating case, in particular the shock duration is at most 50 ms, in particular at most 40, 30 or 20 ms.

[0027] Torque shocks having a maximum of such duration are typically not perceived as an undesirable deviation from the desired driving behavior of the motor vehicle in turbulent operation.

[0028] According to one configuration, the torque shock is determined by the shock interval from a flank alternation, in particular a zero crossing of the load change, i.e. the duration from the first to the last deviation of the shock torque from the normal load change torque, in particular for the current operating case.

[0029] By determining the distance of the shock from the flank alternation it is possible to take into account the dynamic effect of the shock, for example in the form of re-oscillation (reflex), so that an optimal effect of the shock occurs at the time of the flank alternation.

[0030] According to one configuration, the shock transition, particularly with respect to shock intensity and shock duration between shock start and shock end, is given by a deviation function, e.g. a sine function, a cosine function or a polynomial function, and / or the deviation function with respect to the shock duration between shock start and shock end replaces or is superimposed on the torque setting for the output torque transition of the drive machine that was originally set for the load change.

[0031] The deviation of the shock torque from the standard output torque profile of the drive machine integrated over the shock duration represents the braking action on the transmission shaft and thus on the engaged gears. In particular, the interaction of the shock strength and the shock duration makes it possible to set the desired braking action.

[0032] According to one embodiment, the invention can be applied both to the thrust flank and also to the traction flank of a gear transmission.

[0033] Further advantages and applicability of the present invention will become apparent from the following description taken in conjunction with the drawings. [Brief description of the drawings]

[0034] [Figure 1] FIG. 2 shows torque intervention according to the known method for noise reduction during load changes. [Diagram 2] FIG. 13 illustrates a torque shock according to an exemplary configuration of the present invention. [Diagram 3] FIG. 3 illustrates the determination of parameters of the torque shock based on FIG. 2 . [Figure 4] FIG. 4 is a highly simplified diagram of a vehicle drive in which the exemplary method described with respect to FIGS. 2 and 3 may take place. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] FIG. 4 shows an electric vehicle drive 1 having an electric drive machine EM of a motor vehicle, the rotor shaft 2 of which is connected by means of a gear transmission 3 to an output shaft 6 of the motor vehicle and to two wheels 8 which can indirectly rotate thereon.

[0036] The gear transmission 3 comprises a reduction gear stage with gears 4, 5 which mesh with each other and are therefore capable of performing a common rotational movement D dependent on each other in accordance with the settings of the drive machine EM, except for play in the teeth (not shown).

[0037] The setting of the rotary movement D is also performed by the control device SM of the electric drive machine EM corresponding to the embodiment of figures 2 and 3. The known method described in figure 1 can also be implemented by hardware components of the vehicle drive 1.

[0038] FIG. 1 shows a known method for controlling an electric vehicle drive with hardware according to FIG. 4 (with known control means) on the basis of a graph during load variations of the drive machine.

[0039] Flank (tooth surface, engagement surface) replacement F * In the range of ·* VF )(" · " represents a dot on a letter for convenience. The same applies in the following description and in the claims.) and the following (M ·* NF ) the torque gradient M ·* F The torque curve M of the motor output torque is formed* It can be seen from.

[0040] Correspondingly, a profile of the (output) rotational speed n of the electric drive machine is made.

[0041] Additionally, the structure-borne sound acceleration K is plotted on the graph. This is used as an indicator for the noise: the higher the structure-borne sound acceleration K, the louder the noise is expected to be.

[0042] In the known solution, the moment gradient M ·* F Despite known countermeasures to reduce the absolute value of the motor output moment M * It can be seen from the graph that at each zero crossing of k there occurs a large peak in the structure-borne noise acceleration K and thus undesirable noise in the transmission. In the known method, therefore, additional and expensive noise insulation is required.

[0043] In contrast to this, in FIGS. 2 and 3 a method for controlling an electric drive machine EM in a vehicle drive 2 according to FIG. 4 is described:

[0044] In the event of a load change of the drive machine EM, before the flank change F of the gear transmission 3, the torque shock S of the drive machine is controlled due to the adaptation of the common rotational movement D of the gears 4, 5.

[0045] As a result, the flanks of the two gears 4, 5 which abut against each other due to tooth play after the flank change collide with each other at a smaller relative speed, which makes it possible to avoid poor perceived quality of the transmission due to loud noise.

[0046] In this embodiment, the torque shock S is M ·* F1 From M ·* F2 to, and M ·* F2 From M ·* NFTorque gradient transition M with at least two sign changes to · * V F , M ·* F1 , M ·* F2 , M ·* NF This allows for a relatively strong intervention in the output torque curve M of the drive machine EM in a short, imperceptible time t_ges.

[0047] In the case of a load change L on the thrust flank, a decelerating torque shock S occurs, whereas in the case of a load change L2 on the traction flank, an accelerating torque shock S2 occurs, making it possible to achieve noise reduction in both possible types of load changes.

[0048] In the present example, the torque shock L ends before the start of the flank change F. This makes it possible to accurately predict the effect of the torque shock L, since no intervention takes place during the idle phase; the required torque shock S can be apportioned (adjusted).

[0049] The torque shock S is then determined by its shock intensity A, i.e. the deviation of the shock torque from the normal load change torque M for the flank change for the current operating case, in particular at the time tA_max=t_F-t_1. The shock intensity A is around 10 Nm during this time, which is typically not perceived as an influence on the driving behavior during vehicle operation.

[0050] The torque shock S is also determined by its shock duration t_ges. In this embodiment, the shock duration t_ges is a maximum of 40 milliseconds so that the shock is not perceptible in appropriate driving situations, particularly when maneuvering or parking.

[0051] The torque shock S is also determined by the F shock interval t_1 from the flank change, which makes it possible to take into account the dynamic action of the shock, for example in the form of re-oscillation (reflex), so that an optimal action of the shock occurs at the time of the flank change.

[0052] In the vehicle drive unit 1 of the embodiment, a table is stored in the memory of the control device SM, which makes it possible to determine the torque shock S to be controlled for the expected operating state of the vehicle or drive unit 1. The table is data based on test and / or simulation runs and contains values ​​for the shock intensity A, the shock duration t_ges and the shock interval t_1 to be used for each set operating state.

[0053] FIG. 3 shows the results of tests / simulations for data generation of the table in two graphs (where shock intensity is plotted against shock interval or shock duration) for an exemplary operating condition, each graph containing data points 11, 12 for determining the torque shock for illustrative purposes, at which the remaining (maintained) structure-borne sound acceleration K is minimal, and therefore the noise that can be expected is minimal.

[0054] Based on the combination of both entered data points 11, 12, the table can be filled (written) such that the torque shock is determined for the indicated operating condition based on the parameters shock strength A, shock duration t_ges and shock interval t_1, and during operation, when a load change occurs, can be controlled in the indicated operating condition. [Explanation of symbols]

[0055] 2 rotor shaft 3 Gear transmission 4,5 Gears 6 Output shaft A Shock Strength D. Rotational motion EM Electric Drive Machine F Frank replacement K Solid-borne sound L Load Fluctuation M Motor output moment change M · Torque gradient n Revolutions per minute S, S2 Torque shock SM Control device (control means) t_ges Shock duration t_1 Shock interval from flank change

Claims

1. A method for controlling an electric drive machine (EM) of a motor vehicle, the rotor shaft (2) of the electric drive machine being coupled to an output shaft (6) of the motor vehicle by means of a gear transmission (3), the method comprising:

1. A method according to claim 1, characterized in that, during a load change (L) of the drive machine, before a flank change (F) of the gear transmission, a torque shock (S, S2) of the drive machine is set in order to adapt, in particular, a common rotational movement (D) of the gears (4, 5) of the gear transmission.

2. The torque shock is a torque gradient transition (M ・＊ ＶＦ , M ・＊ Ｆ１ , M ・＊ Ｆ２ , M ・＊ ＮＦ 2. The method of claim 1, further comprising:

3. 3. The method according to claim 1, further comprising the step of: generating a decelerating torque shock (S) during a load change on the thrust flank; and / or generating an accelerating torque shock (S2) during a load change on the traction flank.

4. 3. The method according to claim 1, wherein the torque shock ends before the start of flank alternation.

5. 3. The method according to claim 1, wherein the torque shock is determined by a shock intensity (A).

6. 3. The method according to claim 1, wherein the torque shock is determined by a shock duration (t_ges).

7. 7. The method according to claim 6, characterized in that the shock duration is at most 50 ms, in particular at most 40, 30 or 20 ms.

8. 3. The method according to claim 1, wherein the torque shock is determined by the shock interval (t_1) from the flank alternation.

9. 3. The method according to claim 1, wherein the shock curve is given by a deviation function and / or the deviation function for the shock duration (t_ges) replaces or is superimposed on the output torque curve of the drive machine which was originally set for the load change.

10. 3. A device (SM) for controlling an electric drive machine (EM) of a motor vehicle, the rotor shaft (2) of the electric drive machine being coupled to an output shaft (6) of the motor vehicle by means of a gear transmission (3), characterized in that the device is configured to carry out the method according to claim 1 or 2.

Images