METHOD FOR OPERATING A DRIVE ARRANGEMENT

Description

State of the art

[0001] The invention relates to a method for operating a drive arrangement, in particular for a vehicle, according to the preamble of claim 1.

[0002] In drive arrangements with an electric machine, it is usually intended that this can be coupled to and uncoupled from an output element, e.g. an output shaft. For such a coupling process, it is necessary to coordinate the speeds of the electric machine and the output element. The uncoupled electric machine is usually stationary and not rotating. For the coupling process, the electric machine must be accelerated to a certain speed. There are various models for this type of speed regulation. Different influences such as friction, speed gradient or rate of change are taken into account in the models.

[0003] Such models are described, for example, in DE 10 2009 055 246 A1 and DE 10 2012 003 020 A1.

[0004] From DE 100 38 331 A1 a method for operating a drive arrangement is known in which a drive shaft can be coupled in a coupling process to a coupling element of a coupling device in a rotationally fixed manner and can be uncoupled from this in a decoupling process, wherein during the coupling process a toothing of a coupling element of the coupling device and a toothing of the coupling element are brought into positive engagement with one another and wherein before or during the coupling process a speed regulation of the speed of the drive shaft relative to the speed of the coupling element is carried out. Disclosure of the invention

[0005] The problem underlying the invention is solved by a method for operating a drive arrangement, in particular for a vehicle, having the features of claim 1. Advantageous developments of the invention are mentioned in the subclaims.

[0006] According to the invention, a method for operating a drive assembly, in particular for a vehicle, is proposed. The drive assembly comprises a drive shaft. The drive shaft is coupled to a drive, in particular an electric machine (electric motor), in particular in a rotationally fixed manner or by means of a gearing (e.g., a spur gear stage).

[0007] The drive assembly further comprises a coupling element. This can be, for example, a toothing or gear / pinion coupled to an output shaft, an intermediate shaft, or a loose wheel arranged on the drive shaft.

[0008] The drive assembly further comprises a clutch device with a clutch element (e.g., a shift sleeve), wherein the clutch element is rotationally fixedly coupled to the drive shaft. The clutch element is rotationally fixedly coupled to the drive shaft, in particular by means of a gear arranged on the drive shaft or a guide hub with a toothing arranged on the drive shaft. The clutch element is displaceable, in particular, axially (i.e., along the longitudinal direction of the drive shaft or parallel to the central longitudinal axis of the drive shaft).

[0009] The drive shaft can be rotationally coupled to the coupling element in a coupling process and decoupled from it in a decoupling process. During the coupling process, a toothing (in particular an internal toothing) of the coupling element and a toothing (in particular an external toothing) of the coupling element are brought into positive engagement with one another. For this purpose, the coupling element is displaced, in particular, axially.

[0010] In particular, the coupling element runs with its internal toothing on a corresponding external toothing of the guide hub or gear.

[0011] Before and / or during the coupling process, the speed of the drive shaft is regulated relative to the speed of the coupling element (or the output shaft, intermediate shaft, or idler gear coupled to it). In this case, speed regulation refers in particular to an adjustment, compensation, or synchronization of the speeds of the drive shaft and the coupling element, or the differential speed.

[0012] The speed control is adjusted depending on the degree of wear of the teeth of the coupling element and / or the teeth of the coupling element (in particular, depending on the tooth profile of the elements that positively couple with each other). The number of coupling operations performed between the coupling element and the coupling element is recorded, and the degree of wear of the teeth of the coupling element and / or the teeth of the coupling element is determined from the recorded number of coupling operations performed. This allows an estimate of the actual tooth geometry caused by wear to be derived.

[0013] Wear on the coupling elements, which, for example, changes the geometry of the gearing of the respective elements, has a particular influence on the coupling behavior of the coupling elements. By adjusting the speed control depending on wear, the coupling process can be optimally adjusted over the entire service life of a drive assembly. This contributes to positive and consistent feedback for the operator of the drive assembly or the vehicle.

[0014] The clutch time, i.e., the time that elapses during a clutch engagement, depends on the speed difference between the coupling elements. If the speed difference is too small (in both the positive and negative directions of rotation), the clutch time is long. If the speed difference is too large, the gear teeth of the coupling elements repel each other, and the clutch time increases. There is therefore a target speed difference range (or a target speed difference, a target speed difference value) at which the clutch time is minimal. It is desirable to minimize the clutch time so that the clutch engagement does not negatively impact, for example, driving comfort.

[0015] Due to the wear of the coupling elements, the differential speed target range (or the target speed difference) at which the coupling process can be carried out optimally shifts.

[0016] According to a further development, the number of coupling operations carried out between the coupling element and the coupling element (i.e. the total number of coupling operations carried out since the drive arrangement was put into operation) can be recorded by means of a counting device or a sensor.

[0017] According to a further development, a characteristic curve, particularly one that is previously determined (simulated by a model or empirically determined), representing the degree of wear of the teeth of the clutch element and / or the teeth of the coupling element can be determined and stored in a memory. The characteristic curve represents, in particular, the shift in the differential speed target range (or the target speed difference) as a function of the wear. The characteristic curve can be stored, in particular, in a control device of the clutch device or the drive arrangement.

[0018] In particular, the target speed difference increases with the number of clutch operations performed (i.e., with increasing wear), while at the same time, the minimum clutch time decreases. In other words, the minimum clutch time can be further reduced over the service life of the drive assembly by adjusting the speed control according to the characteristic curve.

[0019] According to a further development, the speed regulation can be adjusted depending on the characteristic curve stored in the memory.

[0020] According to a further development, for speed regulation, the speed of the clutch element (or the drive shaft) can be adapted to the speed of the coupling element, in particular by increasing the speed of the drive shaft. This can be implemented in particular by starting up (from a previous standstill) and / or accelerating the electric motor.

[0021] According to a further development, during the coupling process, the teeth of the coupling element and the teeth of the coupling element can be brought into engagement with one another at a desired, in particular predetermined, target speed difference (or a target speed difference value or range) between the speed of the coupling element (or the drive shaft) and the speed of the coupling element. This minimizes the coupling time.

[0022] According to a further development, the target speed difference (or a target speed difference value or range) can be calibrated (readjusted or set) depending on the degree of wear of the teeth of the coupling element and / or the teeth of the coupling element.

[0023] An embodiment of the invention will be explained below with reference to the accompanying drawings. Figure 1 shows a schematic representation of a drive arrangement; Figure 2 shows a schematic representation of toothings of a coupling element, a clutch element and a guide hub before a coupling process; Figure 3 shows a schematic representation of the toothings according to Figure 2 during the coupling process; Figure 4 a schematic representation of the gearing according to Figure 2 after the coupling process; and Figure 5 shows a schematic representation of a gear geometry changing due to wear.

[0024] The drive arrangement contributes to Figure 1 overall the reference number 10. The drive arrangement 10 can, for example, be designed as an E-axle or form part of an E-axle.

[0025] Here, the method is explained by way of example using the drive assembly 10 shown in the figures. The method according to the invention, which is defined by the claims, is not limited to the drive assembly 10 shown, but can also be carried out on other drive assemblies with a clutch.

[0026] The drive assembly 10 has a drive shaft 12. This is coupled to an electric motor (not shown) via the gear 11. An idler gear 13 is arranged on the drive shaft 12, which meshes, for example, with a differential (not shown). A coupling element 14 is arranged on the idler gear 13.

[0027] The drive arrangement 10 has a coupling device 16 with a coupling element 18. The coupling element 18 has a toothing 20 (internal toothing) and the coupling element 14 has a toothing 22 (external toothing) (see Fig.1 and 2 ).

[0028] A guide hub 25 with a toothing 27 (external toothing) is arranged on the drive shaft 12 in a rotationally fixed manner (cf. Fig.1 and 2 ). The coupling element 18 is arranged on the guide hub 25 in a rotationally fixed manner, wherein the (internal) toothing 20 of the coupling element 18 and the (external) toothing 27 of the guide hub 25 are in engagement with one another.

[0029] The clutch element 18 is designed to be axially displaceable. In other words, the clutch element 18 can be moved parallel to the central longitudinal axis 28 of the drive shaft 12. For this purpose, the clutch device 16 in the example has a shift fork 30, which can be driven or moved axially, i.e., parallel to the central longitudinal axis 28 of the drive shaft 12, by means of an electric drive 32.

[0030] The Figure 1 The drive arrangement 10 shown is in a state before a coupling process (coupling element 14 and coupling element 18 not (yet) coupled to one another).

[0031] Figure 2 shows a schematic representation of the toothing 22 of the coupling element 14, the toothing 20 of the coupling element 18 and the toothing 27 of the guide hub 25 before the coupling process.

[0032] Before the coupling process, the toothing 20 of the coupling element 18 is arranged at a distance from the toothing 22 of the coupling element 14.

[0033] Figure 3 shows a schematic representation of the gears 20, 22, 27 according to Figure 2 during the clutch operation. In the example, the shift fork 30 (see Fig. 1 ) the coupling element 18 in the direction of the coupling element 14 (in Figure 3 to the left).

[0034] Depending on the speed difference between the clutch element 18 and the coupling element 14, the gear teeth 20, 22 of the clutch element 18 and the coupling element 14 either engage directly or the gear teeth 20, 22 repel each other several times before engaging. This results in high material stress, particularly at the corner areas 33 of the gear teeth 20, 22, and corresponding wear or deformation of the material.

[0035] The number of repulsions before the gear teeth 20, 22 engage may depend on the speed difference between the coupling element 18 and the coupling element 14 and on the gear geometry.

[0036] Figure 4 shows a schematic representation of the gears 20, 22, 27 according to Figure 2After the coupling process, the teeth 22 of the coupling element 14 and the teeth 20 of the coupling element 18 are now engaged with each other. Thus, the coupling element 14 and the coupling element 18 are coupled to each other in a rotationally fixed manner. In the coupled state, the rotational speeds of the coupling element 14 and the coupling element 18 are equal.

[0037] Figure 5 shows a schematic representation of a gear geometry changing due to wear. An unworn, i.e. not yet worn, gear geometry is shown in Figure 5 with the reference number 34. A worn tooth geometry is indicated in Figure 5 provided with the reference numeral 36. It is schematically shown that material removal and / or deformation occurs, particularly in the corner regions 33 of the toothing.

[0038] As mentioned above, the repulsion of the gear teeth 20, 22 of the coupling element 14 and the clutch element 18 during a coupling process depends on the gear geometry. Thus, with the unworn gear geometry 34, more repulsion can be expected before the gear teeth 20, 22 engage than with the closed gear geometry 36, particularly due to the initially still angular corner regions 33. In other words, the rounded (worn) corner regions 33 of the gear teeth 20, 22 slide past each other more easily for engagement. Accordingly, the gear teeth 20, 22 of the coupling element 14 and the clutch element 18 can engage better with each other at a higher differential speed.

[0039] Thus, by adjusting the differential speed depending on the wear, especially a degree of wear, the clutch time can be minimized and thus the clutch process can be optimized.

Claims

1. Method for operating a drive arrangement (10), in particular for a vehicle, comprising - a drive shaft (12), - a coupling element (14), - a clutch device (16) with a clutch element (18), wherein the clutch element (18) is coupled fixedly to the drive shaft (12) for conjoint rotation, - wherein the drive shaft (12) can be coupled fixedly to the coupling element (14) for conjoint rotation in a coupling operation and can be decoupled therefrom in a decoupling operation, - wherein, during the coupling operation, a toothing system (20) of the clutch element (18) and a toothing system (22) of the coupling element (14) are brought into engagement with one another in a form-fitting manner, - wherein a speed regulation of the speed of the drive shaft (12) relative to the speed of the coupling element (14) is carried out before and / or during the coupling operation, characterized in that the speed regulation is adapted in a manner dependent on a degree of wear of the toothing system (20) of the clutch element (18) and / or the toothing system (22) of the coupling element (14), wherein the number of performed coupling operations of the clutch element (18) to the coupling element (14) is recorded, and the degree of wear of the toothing system (20) of the clutch element (18) and / or the toothing system (22) of the coupling element (14) is determined from the recorded number of performed coupling operations.

2. Method according to Claim 1, characterized in that the number of performed coupling operations of the clutch element (18) to the coupling element (14) is recorded by means of a counting device or a sensor.

3. Method according to either of the preceding claims, characterized in that a characteristic curve representing the degree of wear of the toothing system (20) of the clutch element (18) and / or the toothing system (22) of the coupling element (14) is determined and stored in a memory.

4. Method according to Claim 3, characterized in that the speed regulation is adapted in a manner dependent on the characteristic curve stored in the memory.

5. Method according to Claim 4, characterized in that, for speed regulation, the speed of the clutch element (18) is adapted to the speed of the coupling element (14), in particular by increasing the speed of the drive shaft (12).

6. Method according to one of the preceding claims, characterized in that, during the coupling operation, the toothing system (20) of the clutch element (18) and the toothing system (22) of the coupling element (14) are brought into engagement with each other at a desired, in particular predetermined, target speed difference between the speed of the clutch element (18) and the speed of the coupling element (14).

7. Method according to Claim 6, characterized in that the target speed difference is calibrated in a manner dependent on the degree of wear of the toothing system (20) of the clutch element (18) and / or the toothing system (22) of the coupling element (14).