Parking lock wheel for a parking lock device, parking lock device and motor vehicle

Abstract

The invention relates to a parking lock wheel (1) for a parking locking device, a parking locking device comprising the parking lock wheel (1), and a motor vehicle comprising the parking locking device. The parking lock wheel (1) has a spoke portion (2) whose spokes (3) extend radially outward from a hub (4) of the parking lock wheel (1) and are formed according to a spoke geometry curve (9). Furthermore, the parking lock wheel (1) has a locking tooth ring (5) whose locking tooth gap (7) is formed according to a gap geometry curve (15), and whose locking tooth (6) has an axial material recess (8) formed according to a recess geometry curve (16). One or more of the geometry curves (9, 15, 16) is / are a continuous curve.

Description

[0001] The present invention relates to a parking lock wheel for a parking lock device for a motor vehicle, a parking lock device having such a parking lock wheel, and a motor vehicle having such a parking lock device.

[0002] Conventional parking lock devices have a parking lock gear with a toothed arrangement that is directly or indirectly connected to a wheel hub of the motor vehicle in a rotationally fixed manner. In the parking lock position, a parking lock pawl engages the toothed arrangement, preventing the parking lock gear and, consequently, the wheel hub connected to it in a rotationally fixed manner from rotating, thus preventing the motor vehicle from rolling away unintentionally. A conventional parking lock device with a conventional parking lock gear is known, for example, from DE 10 2020 203 452 A1, DE 10 2018 220 503 A1, or DE 11 2011 104 900 T5.

[0003] If the parking lock gear is (still) rotating at a (residual) speed while the parking pawl is engaging the toothing, a tooth flank of the toothing and the parking pawl will strike each other. Such a strike is perceptible to a user of the vehicle and can be interpreted as a fault noise. To mitigate such a strike, it is necessary to design the parking lock gear to be tangentially and / or circumferentially resilient or reversibly elastic. Another requirement is to make the parking lock gear as stable as possible so that the vehicle cannot roll away unintentionally when the parking pawl is engaged. Furthermore, there is a need to design the parking lock gear as light as possible in order to achieve a particularly lightweight parking lock device and, consequently, a particularly lightweight vehicle.For this purpose, it is known, for example, to make a web of the parking lock gear axially thinner than the toothing and / or to provide the web with material-free areas, for example with holes or the like.

[0004] The object of the present invention is to create a particularly lightweight parking lock wheel without having to accept any loss in terms of stability and elastically reversible compliance of the parking lock wheel.

[0005] This problem is solved by the subject matter of the independent claims. Further possible embodiments of the invention are disclosed in the subclaims, the description, and the figures. Features, advantages, and possible embodiments presented in the description for one of the subject matter of the independent claims are to be regarded, across categories and embodiments, at least analogously as features, advantages, and possible embodiments of the respective subject matter of the other independent claims, as well as any possible combination of the subject matter of the independent claims, optionally in conjunction with one or more of the subclaims.

[0006] According to the invention, a parking lock gear is proposed which, in its intended installation position, forms a component of a parking lock device according to the invention. According to the invention, a motor vehicle is also proposed that has the parking lock device. The parking lock gear is located, in particular—as provided by a possible further development of the motor vehicle—directly on a rotor shaft of a traction motor of the motor vehicle. The traction motor is designed, for example, as an electric machine, which means that the motor vehicle can be designed as a purely electric or hybrid-electric drive vehicle.

[0007] The parking lock gear has a spoke portion with spokes that each extend radially outward from a hub of the parking lock gear. The design of the spokes is based on a spoke geometry curve. In other words, each spoke is formed according to the spoke geometry curve. Furthermore, the parking lock gear has a locking gear rim with locking teeth, with two locking teeth that are directly consecutive along the circumferential direction of the parking lock gear being spaced apart from each other by a locking tooth gap. The hub and the locking gear rim are firmly connected to each other by means of the spoke portion or spokes. The spoke portion and the locking gear rim are, for example, materially bonded to each other, for example, formed integrally with each other, in particular, formed together. The parking lock gear can be manufactured as a forged part.High-strength steel, such as heat-treatable steel (especially forgeable steel), is a suitable material for the parking lock wheel. The locking teeth are spaced equidistantly from one another in the circumferential direction. The design of the locking tooth gap is based on a gap geometry curve, which is why the respective locking tooth gap is formed according to the gap geometry curve. Each locking tooth has an axial material recess, the design of which is based on a recess geometry curve. This means that the respective locking tooth has an axial material recess formed according to the recess geometry curve. One or more of the geometry curves—that is, the spoke geometry curve and / or the gap geometry curve and / or the recess geometry curve—is / are a curvature-continuous curve.

[0008] Thanks to the geometry curves and the design elements based on them, the parking lock gear has, on the one hand, particularly low mass, and, on the other hand, tangential compliance with high stability is ensured. Particular attention has been paid to mitigating what is known as rotor runout. Rotor runout occurs in purely or hybrid electric vehicles when the rotor shaft of the electric traction motor is still rotating and a parking pawl of the parking lock device engages one of the locking tooth spaces, i.e. when the wheel hub and the rotor shaft are rigidly coupled or via a fixed gear ratio, while the parking lock device is adjusted to its parking lock position. In this case, a tooth flank of the locking gear ring and the parking pawl strike each other tangentially or along the circumferential direction of the parking lock gear.Due to the moment of inertia of the comparatively massive rotor core, which is firmly connected to the rotor shaft and is connected to the rotor shaft, the rotor impact is at least severe enough that it can be interpreted by a vehicle user as annoying or as a fault noise. Due to the specific geometry of the parking lock gear described above and the resulting advantageous tangential, reversibly elastic compliance, such a rotor impact is significantly mitigated, i.e., some of the energy of the impact is converted into deformation work for the elastically reversible deformation of the parking lock gear. This protects both the parking lock gear and consequently the parking lock device as a whole, and the electric traction motor. Furthermore, the user no longer perceives the rotor impact as strongly acoustically.

[0009] According to another possible embodiment, the spoke geometry curve is a parabola, whereby a force introduced tangentially into the parking lock gear when the parking pawl is engaged in one of the locking tooth spaces is dissipated particularly efficiently through the parking lock gear. In other words, a mechanically particularly favorable force path results through a material body of the parking lock gear or between the hub and the locking tooth, against which the parking pawl rests tangentially. Furthermore, the parabola supports the reversibly elastic deformability of the parking lock gear.

[0010] In a possible refinement, the parabola opens toward the hub, with one vertex of the parabola lying on a radius line that passes through the center of the locking tooth. In particular, the vertex lies at an edge of the parking lock gear; for example, the vertex and the center of gravity of the corresponding locking tooth coincide. This results in an even more favorable deformation behavior of the parking lock gear.

[0011] In a further possible embodiment, the parking lock gear has three locking teeth and consequently parabolas that directly follow one another in the circumferential direction of the parking lock gear, wherein the parking lock gear has a material-free region that is arranged on an inner side of the central parabola and is defined by a respective outer side of the other two parabolas. The three parabolas overlap in such a way that on the inner side of the central parabola there exists a zone that is enclosed by both parabolic branches of the central parabola and by the parabolic branch of the other two parabolas that faces the central parabola. The material-free region is arranged in this zone. In particular, this region directly borders on the two outer parabolas and is spaced from the central parabola by material of the parking lock gear. In particular, it is provided that the parking lock gear has such a material-free region for each locking tooth.Due to the material-free area, the parking lock gear is designed to be particularly mass-efficient for a given strength (defined, for example, by a boundary condition). Furthermore, the material-free area supports reversibly elastic mobility of the associated locking tooth and thus the desired tangential compliance behavior of the parking lock gear.

[0012] Another possible embodiment provides for the gap geometry curve, according to which the respective locking tooth gap is formed, to be a circle or—viewed three-dimensionally—a right circular cylinder. In the case of a circular cylinder, its longitudinal center axis runs parallel to a longitudinal center axis of the parking lock gear, which axially passes through the hub. Thus, the locking tooth gaps are each designed to be particularly stress-efficient, whereby stress in the material of the parking lock gear resulting from the tangential deformation to mitigate rotor runout is distributed particularly efficiently within the parking lock gear.

[0013] In a possible refinement, the recess geometry curve according to which the axial material recess of the locking gear ring is formed is a circle or, viewed three-dimensionally, a sphere. Due to the axial material recess, the respective locking tooth has a beneficially soft support structure, which promotes the desired tangential elastically reversible deformability / compliance. Furthermore, the axial material recess helps compensate for angular errors of the parking lock gear, and the parking lock gear is also particularly lightweight.

[0014] According to a further design, the locking tooth has an axial material recess on both sides, formed according to the recess geometry curve. Viewing the respective locking tooth along the circumferential direction of the parking lock gear, the locking tooth has a centrally tapered shape ("hourglass shape"), which contributes to mass efficiency for a given strength of the parking lock gear. This is because the tapered portion of the respective locking tooth plays only a minor role in force and / or shock transmission compared to its flanks, so material and thus mass can be omitted at this point.

[0015] Further features of the invention may emerge from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features shown below in the description of the figures and / or in the figures alone, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0016] The drawing shows Fig. 1 a perspective view of a parking lock wheel of a parking lock device, Fig. 2 a view of the parking lock wheel along its longitudinal center axis, Fig. 3 a view of the parking lock wheel along its outer peripheral radius and Fig. 4 a perspective view of the parking lock wheel in a further embodiment.

[0017] The following describes a parking lock wheel 1, a parking lock device (not shown) having the parking lock wheel 1, and a motor vehicle (not shown) having the parking lock device. In the figures, identical and functionally identical elements are provided with the same reference numerals. For easy orientation, a longitudinal center axis A of the parking lock wheel 1 and its outer circumferential radius R are also shown in the figures.

[0018] Fig. 1 shows a perspective view of the parking lock gear 1 of the parking lock device, which in this case forms a component of the motor vehicle. The motor vehicle has an electric traction motor and is therefore designed as a purely electric or hybrid-electric motor vehicle. A rotor shaft and the parking lock gear 1 are connected to one another in a rotationally fixed manner. In the present example, the parking lock gear 1 is seated in a rotationally fixed manner on the rotor shaft of the electric traction motor. The parking lock gear 1 comprises a spoke portion 2, the spokes 3 of which (for reasons of clarity, not all of which are provided with the reference numeral in the figures) extend radially outward from a hub 4 of the parking lock gear 1. Furthermore, the parking lock gear 1 has a locking gear rim 5, which has locking teeth 6, here eight of them.Two locking teeth 6 that are directly consecutive along the circumferential direction of the parking lock wheel 1 are each spaced apart from one another by a locking tooth gap 7. The locking gear rim 5 or its respective locking tooth 6 has, according to . Fig. 1 further comprises an axial material recess 8, of which not all are provided with the reference symbol in the figures for reasons of clarity.

[0019] Fig. Figure 2 shows a view of the parking lock wheel 1 along its longitudinal center axis A, wherein it can be seen that the spokes 3 of the spoke portion 2 are each formed according to a spoke geometry curve 9, which in this case is a parabola 10. The respective parabola 10 is open towards the hub 4, wherein a vertex 11 of the parabola 10 lies on a radius line 12, which passes centrally through the respective locking tooth 6. As can be seen from Fig. 2, the vertex 11 is located at an edge of the parking lock wheel 1, for example, the vertex 11 and a center of gravity of the associated locking tooth 6 coincide.

[0020] Fig. 2 that three parabolas 10 of the locking teeth 6 that are directly consecutive in the circumferential direction of the parking lock wheel 1 overlap with one another in such a way that a zone 13 exists on the inside of the central parabola 10 that is enclosed by both parabolic branches of the central parabola 10 and by the parabolic branch of the other two parabolas 10 that faces the central parabola 10. A material-free region 14 is arranged in zone 13, which here directly borders the two outer parabolas 10, and is spaced from the central parabola 10 by material of the parking lock wheel 1. The material-free region 14 is therefore arranged on the inside of the central parabola 10 and defined by a respective outer side of the other two parabolas 10. In this example, the parking lock wheel 1 has one such material-free region 14 for each locking tooth 6.

[0021] It continues Fig. 2 shows that, according to the example described here, a gap geometry curve 15, according to which the respective locking tooth gap 7 is formed, is a circle or—viewed three-dimensionally—a right circular cylinder. In the case of the circular cylinder, its longitudinal center axis runs parallel to the longitudinal center axis A of the parking lock gear 1.

[0022] Fig. Figure 3 shows a view of the parking lock gear 1 along its outer circumferential radius R. It can be seen that the respective axial material recess 8 is formed according to a recess geometry curve 16, which in the present example is a circle or—viewed three-dimensionally—a sphere. In the present case, the respective locking tooth 6 has an axial material recess 8 formed on both sides according to the recess geometry curve 16.

[0023] The respective geometry curve 9, 15, 16 is in any case a curvature-continuous curve.

[0024] Fig. Figure 4 shows a perspective view of the parking lock wheel 1 in a further embodiment, wherein it can be seen that not all of the structural elements 3, 7, 8 need to be designed according to the corresponding curvature-continuous geometry curve 9, 15, 16. Rather, according to the invention, it is provided that the respective spoke 3 and / or the respective locking tooth space and / or the respective axial material recess 8 is designed based on the respective curvature-continuous geometry curve 9, 15, 16. Thus, Fig. 4 shows an exemplary embodiment of the parking lock gear 1, whose locking tooth spaces 7 are angular, i.e., formed according to a curve with discontinuous curvature. Furthermore, it can be seen that additional material-free regions 17 can be provided, with each additional material-free region 17 being located in a zone between two parabolas 10 directly following one another in the circumferential direction of the parking lock gear 1. List of reference symbols 1 parking lock wheel 2 spoke share 3 spokes 4 Hub 5 locking gear 6 locking teeth 7 Interdental space 8 Material recess 9 Spoke geometry curve 10 Parable 11 Vertex 12 radius lines 13 Zone 14 material-free area 15 Space geometry curve 16 Recess geometry curve 17 material-free area A Longitudinal center axis R outer peripheral radius QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2020 203 452 A1

[0002] DE 10 2018 220 503 A1

[0002] DE 11 2011 104 900 T5

[0002]

Claims

[1] Parking lock wheel (1) for a parking lock device for a motor vehicle, the parking lock wheel (1) comprising: - a spoke portion (2), the spokes (3) of which extend radially outward from a hub (4) of the parking lock wheel (1) and are formed according to a spoke geometry curve (9), - a locking tooth rim (5), the locking tooth gap (7) of which is formed according to a gap geometry curve (15), and the locking tooth (6) of which has an axial material recess (8) formed according to a recess geometry curve (16), wherein one or more of the geometry curves (9, 15, 16) is / are a curve of continuous curvature. [2] Parking lock wheel (1) according to claim 1, characterized by that the spoke geometry curve (9) is a parabola (10). [3] Parking lock wheel (1) according to claim 2, characterized bythat the parabola (10) is open towards the hub (4) and a vertex (11) of the parabola (10) lies on a radius line (12) which passes through the center of the locking tooth (6). [4] Parking lock wheel (1) according to claim 2 or 3, characterized by three locking teeth (6) and consequently parabolas (10) directly following one another in the circumferential direction of the parking lock wheel (1), wherein the parking lock wheel (1) has a material-free region (14) which is arranged on an inner side of the central one of the parabolas (10) and is defined by a respective outer side of the other two parabolas (10). [5] Parking lock wheel (1) according to one of the preceding claims, characterized by that the gap geometry curve (15) is a circle. [6] Parking lock wheel (1) according to one of the preceding claims, characterized by that the recess geometry curve (16) is a circle. [7] Parking lock wheel (1) according to one of the preceding claims, characterized bythat the locking tooth (6) has an axial material recess (8) formed on both sides according to the recess geometry curve (16). [8] Parking lock device for a motor vehicle, which has a parking lock wheel (1) designed according to one of the preceding claims. [9] Motor vehicle with a parking lock device designed according to one of the preceding claims. [10] Motor vehicle according to claim 9, characterized by that the parking lock wheel (1) sits directly on a rotor shaft of a traction machine of the motor vehicle.

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