Steering angle limiter having a toothed insert

Abstract

The invention relates to a steering angle limiter (6) of a steer-by-wire steering system, which is connected to a steering shaft (4) of a hand wheel actuator (1), a force feedback transmission or a force feedback motor by means of an interlocking shaft-hub connection, wherein the steering angle limiter (6) designed as a ready-to-install functional unit includes a shaft disk (9) which is connected to the steering shaft (4) by means of an internal toothing (10), wherein, in order to form a locally play-free toothing, the latter is interrupted in at least one partial region and forms a recess (11) which is provided for receiving a deformable and / or radially moveable toothing insert (12).

Description

[0001] P241147

[0002] - 1 -

[0003] Steering angle limiter with a toothed insert

[0004] The invention relates to a steering angle limiter of a steer-by-wire steering system, which is connected to a steering shaft of a hand-wheel actuator (HWA) by means of a positive-locking shaft-hub connection, according to the features of the preamble of claim 1.

[0005] Steer-by-wire steering systems for vehicles receive manual steering commands from the person operating the vehicle by turning the steering wheel. The steering system for the wheels of a steering axle essentially consists of a so-called hand-wheel actuator, an actuator connected to the steering wheel, and a road-wheel actuator (RWA). The steering commands are transmitted electronically from the HWA via cable (by wire) to the RWA, which, for example, transmits the steering movement of the steering wheel to the steerable vehicle wheels by means of steering rods. A previously described steer-by-wire steering system for a vehicle is known from DE 10 2015 224 602 A1.

[0006] WO 2023 147 808 A1 discloses a steer-by-wire steering system in which a steering angle limiter, also called a steering angle limiter, is integrated to limit steering wheel rotation. The steering angle limiter, which surrounds the steering shaft and is operatively connected to it, comprises a split stop ring. The two halves of the ring, which can be rotated relative to each other, are assigned to separate tangential stops and are variably adjustable relative to each other. Each half of the ring can be adjusted via an engagement element connected to the steering shaft. Starting from a neutral position of the steering shaft, the steering angle is limited upon reaching either the first or the second stop, depending on the direction of rotation, and consequently, the steering wheel rotation ends.

[0007] KR 10 2018 002 8235 A refers to another steering angle limiter of a steer-by-wire steering system. The assembly comprises a steering shaft guided through a housing with an associated steering wheel and a steering angle limiter designed as a bolt and referred to as a locking unit, which is located outside of P241147

[0008] - 2 -

[0009] The housing is arranged to limit the rotation of the steering wheel to a predetermined range of rotation angles.

[0010] German patent DE 10 2020 128 101 A1 describes a steering angle limiter consisting of a threaded spindle with an associated threaded nut, which is axially movable when the threaded spindle is rotated. To stop axial movement of the threaded nut and thus the rotation of the threaded spindle, a stop arm extending from the threaded nut and parallel to the axis of the threaded spindle can be rusted against a stop pin protruding perpendicularly from the threaded spindle.

[0011] WO 2024 / 142719 A1 shows a steering angle limiter that engages with an external toothing of a steering shaft via an internal toothing of a wave disk.

[0012] Other known steering angle limiters employ solutions where, for example, a shaft-hub connection is provided between the steering shaft and the steering angle limiter to transmit the steering angle limiting torque. Due to the design, the materials used (especially steel), and the requirement for easy installation, a tolerance- and / or assembly-related fit and / or joint clearance is inherent in the gearing. This clearance, and consequently its tendency to wear, causes an undesirable steering feel for the driver, leads to adverse noise, and can also trigger safety-related defects.

[0013] DE 10 2015 001 442 A1 shows a brake arrangement in which tilting and pitching movements are damped by a damping element which engages in the external teeth of a driver.

[0014] The object of the invention is to provide a steering angle limiter that is functionally improved compared to the prior art, with a largely backlash-free and acoustically optimized toothing, which also improves steering comfort. P241147

[0015] - 3 - improved and which can be manufactured easily with minimal effort and is cost-effective overall.

[0016] This problem is solved by means of a steering angle limiter of a hand-wheel actuator constructed according to the features of claim 1. Further preferred embodiments of the invention can be found in the dependent claims, the figures, and the accompanying description.

[0017] According to claim 1, a steering angle limiter is provided, comprising a shaft disk with internal teeth which, together with external teeth of a steering shaft, form a positive-locking and steering torque-transmitting shaft-hub connection, preferably designed as a splined shaft connection. To achieve backlash-free gearing, a recess, also referred to as a break, is provided in at least one section of the gearing to accommodate a deformable and / or displaceable gear insert.

[0018] A gear insert according to the invention is an insert with at least one tooth which is inserted into a recess of the internal toothing of a wave disk and which closes the interruption of the internal toothing by the recess.

[0019] The steering angle limiter forms a ready-to-install, mechanical functional unit.

[0020] The advantage of the proposed solution is that, via the steering angle limiter according to the invention, a largely backlash-free, positive-locking shaft-hub connection between the steering shaft and the shaft disc of the steering angle limiter can be achieved in at least a partial area of ​​the gearing. This local backlash-free operation improves the steering and operating comfort of the vehicle, since neither during a change of steering direction nor when reaching the end stops of the P241147

[0021] - 4 -

[0022] The steering angle limitation results in an unpleasant, adverse steering feel for the driver at the steering wheel.

[0023] Furthermore, the optimized gearing advantageously avoids noise generation, e.g., clicking noises, which in previous solutions occurred, for example, when changing the steering direction or due to vibrations, especially when driving on rough roads. Moreover, the steering angle limiter designed according to the invention prevents safety-relevant defects.

[0024] Advantageously, the relatively small, local recess in the toothing of the shaft-hub connection, also known as a break, has no negative impact on the torque load capacity of the steering angle limiter. Furthermore, the locally backlash-free toothing of the shaft-hub connection ensures unimpeded axial displacement of the shaft disc of the steering angle limiter, which is axially preloaded without backlash by a preload spring, on the steering shaft during operation.

[0025] The mechanical steering angle limiter constructed according to the invention, which includes a backlash-free, positive-locking splined shaft in a partial area, is advantageously manufacturable with little effort, easy to assemble and consequently cost-effective to implement.

[0026] According to a preferred design embodiment, the shaft-hub connection is preferably designed as a splined shaft connection, which simplifies axial assembly of the steering angle limiter. Furthermore, high stop torques can be reliably transmitted, even in conjunction with a space-saving shaft washer with a relatively thin wall thickness in the axial direction. According to the invention, the splined insert is inserted into a radially inwardly open, local recess in the internal splines of the shaft washer of the steering angle limiter. The splined insert, which closes the gap in the internal splines, creates an interference fit with the external splines by means of appropriate design and / or geometry and / or suitable soft material selection.

[0027] - 5 - of the steering shaft. As a measure to simplify assembly during the installation of the steering angle limiter, the toothed connection between the shaft disc and the steering shaft, designed as a shaft-hub connection, is preferably designed as a clearance fit outside the toothed insert. This advantageously allows for tool-free, force-free assembly of the associated components, and in particular, makes it easy to axially displace the shaft disc by means of the preload spring installed in the steering angle limiter.

[0028] Another embodiment provides that the recess in the internal teeth of the shaft disc has at least one step forming an assembly stop for the toothed insert in the axial direction, which is preferably pressed into the recess with an interference fit. Advantageously, the step is arranged such that during assembly, i.e., when the steering angle limiter is fitted onto the steering shaft, the toothed insert is pressed axially against the step and subsequently remains in this intended installation position. The step allows the toothed insert to be fitted axially up to the assembly stop without increasing the shaft disc thickness or the axial installation space of the steering angle limiter.

[0029] This simplifies assembly, reduces costs and contributes to increased quality (Poka-Yoke).

[0030] To further support the self-retention of the gear insert in its intended installation position, the gear insert is secured against radial inward displacement by a suitable retaining geometry. Shaped undercuts on the two lateral boundary surfaces are particularly suitable for this purpose, providing a durable locking mechanism for the gear insert. This advantageously creates a self-retaining, durable locking device for the gear insert during handling and assembly of the steering angle limiter, thus preventing slippage and / or displacement during transport, handling, and installation at the customer's site. Simultaneously, this ensures that no steering angle limiters are installed at the customer's site without the corresponding gear insert. It also prevents interruptions or failures at the customer's assembly machine caused by dislodged gear inserts. P241147

[0031] - 6 - In a further embodiment, the mounting stop is set back as a step from both axial surfaces of the shaft disc and encompassed by a fork-like, double-sided stop of the toothed insert. This allows the steering angle limiter to be slid onto the steering shaft in various applications and directions. Should micro-movements occur during operation, for example due to thermal expansion or vibrations, the positive-locking design effectively prevents slow movement and subsequent dislodgement of the insert.

[0032] According to a further embodiment of the invention, the toothed insert is recessed relative to both side surfaces of the shaft disk, also known as the planar surfaces, so that the wall thickness of the shaft disk exceeds the width of the toothed insert. Due to this design and the interference fit, the elastic toothed insert can expand unhindered in the axial direction during compression in the operating state because it is not limited by any constraints. Advantageously, this also prevents the rolling of the clamping cylinder rollers of the steering angle limiter from being affected, since the toothed insert has a smaller width than the shaft disk when not mounted. The resulting clearance is available for the displaced material of the toothed insert. This ensures that the steering torque is not affected.

[0033] Furthermore, it is planned to manufacture the gear insert from an elastically deformable material. Rubber or plastic, in particular thermoplastic polyurethanes (TPU), thermoplastic elastomers (TPE), or silicones, are preferably suitable materials. For cost advantages, especially for large production runs, it is advantageous to manufacture the gear insert using an injection molding process, in which the elastically deformable material fills the recess of the internal gearing. The injection molding process ensures a durable and cost-optimized fixation of the gear insert. To achieve high component strength, a drive insert designed as a two-component injection-molded part, which is, for example, glass fiber reinforced, can be used. As a further embodiment, a drive insert made of a plastically deformable and therefore calibratable material (P241147) can also be used.

[0034] - 7 -

[0035] A gear insert is used, which snaps into the local recess of the wave disk and is thus secured by force and / or form locking.

[0036] The elastic compliance of the toothed insert allows both the toothed insert to be fitted into the recess of the shaft disc and the steering angle limiter to be fitted onto the steering shaft with minimal force, despite the toothed insert's interference fit. A further advantage lies in the damping effect of the toothed insert, resulting in a soft-stop function.

[0037] Another embodiment provides that, to achieve zero backlash in the shaft-hub connection, the area of ​​the gear insert is designed with an interference fit relative to the internal teeth of the shaft disk. Preferably, a gear insert is provided which is resilient in the radial direction through a corresponding geometric design and / or by means of a separate spring element.

[0038] According to a further embodiment of the invention, a friction-minimizing surface is provided on the gear insert to achieve the lowest possible steering torque. For this purpose, the surface of the gear insert is coated with a friction-reducing material, at least in the area of ​​the teeth. This allows the shaft disc to be moved axially more easily, thereby reducing the axial preload force generated by a spring and resulting in a reduced frictional torque of the steering angle limiter. Furthermore, wear is reduced and the service life is increased. Additionally or alternatively, this effect can be achieved by means of a suitable heat treatment.

[0039] The invention is described in more detail below with reference to preferred embodiments. Identical components or components with the same function are identified by the same reference numerals. This is shown in: P241147

[0040] - 8 -

[0041] Fig. 1 shows a hand-wheel actuator of a steer-by-wire steering system with an integrated steering angle limiter;

[0042] Fig. 2 shows a 3D view of a ready-to-install steering angle limiter;

[0043] Fig. 3 shows the steering angle limiter according to Fig. 2 in an exploded view;

[0044] Fig. 4 shows a wave disk of the steering angle limiter as a single component with associated toothed insert of the first embodiment;

[0045] Fig. 5 enlarges the gear insert according to Fig. 4;

[0046] Fig. 6 shows a wave disk of the steering angle limiter as a single component with a recess for the associated toothed insert according to Fig. 7 of the first embodiment;

[0047] Fig. 7 shows the gear insert of the first embodiment enlarged in a 3D view;

[0048] Fig. 8 shows an enlarged section of the internal toothing of the wave disk shown in Fig. 6 in a 3D view, which shows a recess for the toothing insert according to Fig. 7;

[0049] Fig. 9 shows a wave disk of the steering angle limiter as a single component with associated toothed insert of the second embodiment;

[0050] Fig. 10 shows a wave disk of the steering angle limiter as a single component with associated toothed insert of the third embodiment; P241147

[0051] - 9 -

[0052] Fig. 11 shows a section of the wave disk, illustrating a difference in width between the gear insert and the wave disk;

[0053] Fig. 12 shows a 3D view of a wave disk of a steering angle limiter with a mounting stop offset on both sides and an associated toothed insert.

[0054] Fig. 1 shows a hand-wheel actuator (HWA) 1 of a vehicle's steer-by-wire steering system, which allows the user to influence the vehicle's direction of travel without a direct connection between a steering wheel 2 and the steered vehicle wheels (not shown). The steering angle of the steering wheel 2 is determined by means of rotation angle sensors and transmitted via wire to a road-wheel actuator (RWA), which adjusts the steering wheels via an associated steering mechanism. The HWA 1 shown in Fig. 1, which is of a generally known design, comprises an actuable telescopic extension 3, wherein a rotatable steering shaft 4, also called a steering column, together with the associated end-mounted steering wheel 2, is axially displaceable within a tubular outer housing 5.A mechanical steering angle limiter 6, which surrounds the steering shaft 4, is enclosed on the outside by a connecting structure, a tubular outer housing 5, which is assigned to a guide element 7 of the HWA 1.

[0055] Figures 2 and 3 show the steering angle limiter 6, the basic structure of which is known from the prior art. Figure 2 shows a perspective view of the steering angle limiter 6 as a complete, ready-to-install functional unit, comprising several components enclosed by a housing 8. Figure 3 shows an exploded view of all the annular components of the steering angle limiter 6. A largely visible shaft disk 9 of the steering angle limiter 6 includes an internal toothing 10 that engages with a corresponding external toothing (not shown) of the steering shaft 4, and together they form a positive-locking shaft-hub connection. A toothed insert 12 is also shown. P241147

[0056] - 10 -

[0057] Figures 4 and 5 show the shaft disk 9, whose internal teeth 10 are locally interrupted to form a radially inwardly opening recess 11, in which a toothed insert 12 is fitted with a compression fit. The radially limited projection of the toothed insert 12 creates an interference fit with an external toothing of the steering shaft 4 when installed. Outside the area of ​​the toothed insert 12, a clearance fit is established between the internal toothing 10, the shaft disk 9, and the external toothing of the steering shaft 4.

[0058] In Fig. 6, the wave disk 9 is shown with a recess 21 in the internal toothing 10. The associated toothed insert 12, shown in Fig. 7, encloses a tab 13, 14 at both ends, which, in the installed state, are each supported on a step 15, 16, shown in Fig. 8, of the recess 21. To prevent radial dislodgement, the toothed insert 12 is secured by a self-retaining mechanism. For this purpose, both steps 15, 16 form an undercut 17, 18, which locally overlaps one end zone of the tab 13, 14 of the toothed insert 12.

[0059] The gear insert 22 associated with the internal toothing 10 of the wave disk 9 in Fig. 9 is rigidly fixed in position in the recess 11 of the wave disk 9, for example by vulcanization. Alternatively, the gear insert 22 can be designed as an injection-molded part that permanently fills the recess 11.

[0060] Fig. 10 shows a radially preloaded gear insert 32 integrated into the wave disk 9. A spring effect of the gear insert 32 can be achieved, for example, by a suitable geometric design or, as shown in Fig. 10, by a separate spring element 19, for example, a small leaf spring.

[0061] Fig. 11 shows a section of the shaft disk 9 in a view looking towards the internal teeth 10. A component thickness Si of the shaft disk 9 exceeds a width dimension S2 of the toothed insert 12, which is recessed relative to both lateral planar surfaces of the shaft disk 9. Due to the interference fit P241147

[0062] - 11 - the gear insert 12 is compressed in the operating state and can expand in the axial direction due to the lack of lateral limitation.

[0063] Fig. 12 shows a 3D view of a shaft disk 9 with a toothed insert 42. In contrast to the embodiment in Fig. 6 and Fig. 8, the shaft disk 9 is provided with steps 15, 16 on both sides. The corresponding toothed insert 42 is provided with two stops 13, 14 on each side, so that the stops 13, 14 fork-like encompass the steps 15, 16 and ensure a positive-locking fit of the toothed insert 42 in the shaft disk 9 in both axial directions.

[0064] P241147

[0065] - 12 -

[0066] List of reference signs

[0067] 1 Hand-Wheel Actuator

[0068] 2 Steering wheel

[0069] 3 telescopic extension

[0070] 4 Steering shaft

[0071] 5 outer casings

[0072] 6 Steering angle limiter

[0073] 7 Guide element

[0074] 8 cases

[0075] 9 wave washer

[0076] 10 Internal teeth

[0077] 11 recess

[0078] 12 Gear insert

[0079] 13 tab

[0080] 14 tab

[0081] Level 15

[0082] Level 16

[0083] 17 Undercut

[0084] 18 Undercut

[0085] 19 spring element

[0086] 20 balls

[0087] 21 recess

[0088] 22 Gear insert

[0089] 32 Gear insert

[0090] 42 Gear insert

[0091] Si Component thickness wave washer

[0092] S2 width dimension gear insert

Claims

P241147 - 13 - Patent claims 1. Steering angle limiter (6) - for a steering shaft (4) having external teeth of a hand-wheel actuator (1) of a steer-by-wire steering system - with a wave disk (9) which has an internal toothing (10) provided with a recess (11, 21) for engagement with the external toothing, characterized in that - in the recess (11 , 21 ) a gear insert (12, 22, 32, 42) is arranged to realize local freedom of play.

2. Steering angle limiter (6) according to claim 1 , characterized in that the toothed insert (12, 22, 32, 42) creates an interference fit to the steering shaft (4), wherein outside the toothed insert (12, 22, 32) the toothing between the shaft disk (9) and the steering shaft (4) is designed as a clearance fit.

3. Steering angle limiter (6) according to one of the preceding claims, characterized in that the recess (11 , 21 ) extends over at least two teeth of the external toothing and the toothing insert (12, 22, 32, 42) has at least two teeth.

4. Steering angle limiter (6) according to one of the preceding claims, characterized in that the recess (21 ) of the internal toothing (10) has at least one step (15, 16) forming a mounting stop for the toothing insert (12, 42) in the axial direction, which is pressed into the recess (21 ) with an interference fit.

5. Steering angle limiter (6) according to one of the preceding claims, characterized in that the recess (21) has an undercut (17, 18) which forms a retaining geometry for the toothed insert (12, 42) P241147 - 14 - 6. Steering angle limiter (6) according to one of the preceding claims, characterized in that a component thickness Si of the shaft disk (9) exceeds a width dimension S2 of the toothed insert (12, 22, 32, 42).

7. Steering angle limiter (6) according to one of the preceding claims, characterized in that the toothed insert (12, 22, 32, 42) is made of an elastically deformable material.

8. Steering angle limiter (6) according to one of the preceding claims, characterized in that a toothed insert (12, 22, 32, 42) designed with an interference to the internal toothing (10) is inserted in the wave disk (9).

9. Steering angle limiter (6) according to one of the preceding claims, characterized in that the toothed insert (32) is designed to be radially resilient.

10. Steering angle limiter (6) according to one of the preceding claims, characterized in that the toothed insert (12, 22, 32, 42) has a friction-reducing and / or wear-reducing surface produced by a coating and / or a heat treatment.

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