Steering device and method for a steer-by-wire steering system
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-01-08
- Publication Date
- 2026-08-13
Smart Images
Figure DE2026100006_13082026_PF_FP_ABST
Abstract
Description
[0001] Steering device and method for a steer-by-wire steering system
[0002] The invention relates to a steering device for a steer-by-wire steering system with the features of the preamble of claim 1 and a method for a steer-by-wire steering system with the features of the preamble of claim 10.
[0003] Steer-by-wire steering systems comprise, as their central component, a telescopic steering column consisting of a telescopic housing and a telescopic steering shaft with a steering wheel. The steering column is designed to be adjustable by the occupant to an ergonomically convenient position via an electric longitudinal adjustment actuator. According to the requirements of vehicle manufacturers of autonomous vehicles, it can also be stowed away in the dashboard. Furthermore, steer-by-wire steering systems include a steering rod that interacts with a wheel of the vehicle. This rod is mounted in a longitudinally displaceable and torsionally resistant manner to transmit the steering movement to the wheel.
[0004] Especially in the steering column mounting, large adjustment ranges must be achieved. This results in higher loads on the bearings, and the longer lever arms necessitate stiffer bearings to maintain a familiar, direct steering feel when steering manually. This high stiffness requirement, in turn, demands backlash-free and heavily preloaded bearings. To allow the steering column to be electrically adjusted with minimal effort—i.e., using small and inexpensive electric motors—the bearings themselves must exhibit very low friction, even under these conditions.
[0005] German patent DE 102022 109599 A1 describes a bearing arrangement for a steering column housing of a motor vehicle. The steering column housing has an outer housing which is mounted on a vehicle support element. Furthermore, the steering column housing has an inner housing which contains a rotatably mounted steering shaft, wherein the outer and inner housings are arranged to be displaceable relative to each other. The bearing arrangement is provided between the outer and inner housings, and the bearing arrangement consists of at least one recirculating ball bearing segment. The recirculating ball bearing segment is formed from a sleeve and a cage, wherein a recirculating ball guide is provided in the cage, in which a chain of spherical rolling elements is guided. The recirculating ball guide comprises two straight sections arranged in the direction of the adjustment movement, which are connected to each other at their ends by clearances.This allows the rolling elements to perform a circular motion within the ball recirculation segment while passing through a load zone formed by one of the straight sections. Furthermore, resilient raceway wings with flat running surfaces are arranged laterally on the sleeve, against which the rolling elements bear.
[0006] Against this background, the invention is based on the objective of increasing the safety of a passenger in the vehicle.
[0007] To solve the problem, a bearing with the features of claim 1 and a method with the features of claim 10 are proposed. Further preferred embodiments of the invention can be found in the dependent claims, the figures, and the accompanying description.
[0008] Claim 1 proposes a steering device for a steer-by-wire steering system. The steering device comprises an inner housing element and a bearing for the slidable mounting of an outer housing element on the inner housing element, wherein the bearing has a cage and a spring element, the cage having a ball recirculation channel with a plurality of spherical rolling elements arranged therein, and wherein the spring element forms a contact surface for the rolling elements bearing against it. The cage has a cage pocket with a cylindrical rolling element arranged therein, and the cylindrical rolling element is configured to dissipate a force acting on the inner and / or outer housing element and / or a steering wheel during a crash by rolling with line contact to the inner and / or outer housing element.The proposed solution is based on the understanding that a vehicle's steering system poses a particular danger to passengers, especially drivers, in a crash. In crash situations, forces act on passengers that can lead to a collision with the steering system, such as the steering wheel. This, in turn, can cause injuries. For example, in a frontal collision, after the airbag deploys, a passenger's body can strike the airbag and thus the steering wheel. To reduce the impact energy, the steering wheel must be able to move away from the passenger or yield to the impact force.
[0009] The proposed solution mitigates the aforementioned risk by diverting the force acting on the steering system during a crash. This is achieved using a roller-shaped element that dissipates this force by rolling it in line contact with the inner and outer housing elements.
[0010] The wording, according to which the outer housing element is slidably mounted on the inner housing element, is preferably to be understood as meaning that the inner housing element and outer housing element are slidably mounted relative to each other.
[0011] Preferably, the roller-shaped rolling element is a roller with a rotation axis oriented transversely to a displacement direction of the housing elements.
[0012] The crash is, for example, a frontal crash in which, after the vehicle's airbag is triggered, the passenger's upper body hits the steering wheel.
[0013] The force acting on the housing element and / or the steering wheel during a crash preferably acts on the inner housing element, the outer housing element, the steering wheel, or on the inner and outer housing elements and the steering wheel. The force acting on the inner and / or outer housing element is preferably triggered by a force acting on the steering wheel, the associated steering shaft, and, via the bearings and components within the force transmission path, on the vehicle body. For example, in a frontal crash, a passenger's body strikes the steering wheel. This causes a force to be exerted on the outer and / or housing element.
[0014] The cylindrical rolling element is preferably arranged in the cage pocket with a degree of play, yet in a way that prevents it from falling out. This play allows the cylindrical rolling element to rotate within the cage pocket.
[0015] Preferably, the distance between a surface of the cage and a surface of the inner housing element is greater than the distance between a surface of the cylindrical rolling element and the surface of the inner housing element. This dimension allows for the design definition of a force range in which the cylindrical rolling element does not come into contact with the inner housing element and / or does not come into contact with the outer housing element and / or does not come into contact with both the inner and outer housing elements simultaneously. Depending on these dimensions, it is therefore possible to determine the force threshold at which a crash is to be expected.
[0016] According to a preferred embodiment, a first roller-shaped rolling element is arranged in a displacement direction of the housing elements in front of the ball recirculation channel and / or a second roller-shaped rolling element is arranged in a displacement direction of the housing elements behind the ball recirculation channel.
[0017] In particular, in a design with the first and second roller-shaped rolling elements, the deflection movement is guided stably and jerking and tilting are prevented or at least reduced.
[0018] In another preferred embodiment, the radius of the cylindrical rolling element is larger than the radius of the spherical rolling elements. In this way, the dissipation of the force acting on the steering system during a crash can be designed to be particularly simple, since the cylindrical rolling element can form a bridge between the inner and outer housing elements, while the spherical rolling elements can remain in a space between the inner housing element and the spring element.
[0019] According to another preferred embodiment, the roller-shaped rolling element is mounted in an unloaded state of the steering device or in a steering operation with a clearance between the inner housing element and the outer housing element.
[0020] This prevents the roller element from influencing the handling of the steering system during steering operation, and the steering system is therefore not affected by the roller element. In other words, the roller element has operating clearance.
[0021] The formulation stating that the cylindrical rolling element is mounted with a clearance between the inner and outer housing elements is preferably to be understood as meaning that the distance between a surface of the cylindrical rolling element and a surface of the inner housing element is greater than zero when the rolling element is in contact with the outer housing element. Simultaneously, the distance between a surface of the cylindrical rolling element and a surface of the outer housing element is greater than zero when the rolling element is in contact with the inner housing element. In particular, the aforementioned distances are preferably greater than zero in both an unloaded state and during steering operation.
[0022] In another preferred embodiment, the roller-shaped rolling element is designed to dissipate the force acting on the inner and / or outer housing element and / or the steering wheel in a crash by bridging a mechanical connection which exists in an unloaded state of the steering device or in a steering operation between the inner housing element, the spherical rolling elements, the spring element and / or the outer housing element.
[0023] In this way, frictional contact between the cage and the inner housing element is avoided when the force is transferred.
[0024] Preferably, the cylindrical rolling element is subjected to a radial force when dissipating the force acting on the housing element and / or the steering wheel during a crash. This radial force is preferably exerted on the cylindrical rolling element by the inner and outer housing elements.
[0025] According to a further preferred embodiment, the spring element is designed to be deformable in such a way that the spherical rolling elements can be at least partially submerged into the cage by the force acting on the inner and / or outer housing element and / or steering wheel during a crash, and the cylindrical rolling element comes into contact with the surfaces of the inner and outer housing element.
[0026] This is a particularly suitable design solution for bringing the cylindrical rolling element into contact with the surfaces of the inner and outer housing elements to dissipate the force acting during a crash. The elasticity of the spring element is cleverly utilized to allow the spherical rolling element to plunge into it. This plunge reduces the distance between the cage and the inner housing element until the cylindrical rolling element comes into line contact with the inner housing element and is radially preloaded.
[0027] According to a further preferred embodiment, the cage has a fastening element for attaching the cage to the outer housing element, wherein the fastening element is designed to shear off due to a relative movement between the cage and the outer housing element when the force acting on the housing element and / or the steering wheel during a crash is dissipated. This provides a particularly simple design solution for attaching the cage to the outer housing element for both the unloaded state and steering operation, while simultaneously allowing movement for the dissipation of the force acting on the steering system during a crash. Depending on the material properties and dimensions of the fastening element, it can be specified from which force magnitude and direction dissipation of the acting force is permitted (or prevented by the fastening element).
[0028] Preferably, the fastening element for attaching the cage to the outer housing element is inserted into a bore or recess of the outer housing element.
[0029] In a preferred embodiment, the fastening element is arranged in a self-retaining manner on the outer housing element.
[0030] This allows the fastener to remain attached to the outer housing element while dissipating the force exerted on the steering system during a crash. This prevents a fragment of the fastener from breaking off and obstructing the dissipation of the force exerted on the steering system during a crash or from shifting.
[0031] Preferably, the dimensions of the recess described above are designed to correspond to the fastening element in such a way that the fastening element is clamped and held in the recess after shearing.
[0032] In another preferred embodiment, the inner housing element comprises an inner housing and the outer housing element comprises an outer housing of a hand-wheel actuator. This results in particularly suitable and advantageous applications for the bearings.
[0033] Furthermore, according to claim 10, a method for a steer-by-wire steering system is proposed. In this method, an outer housing element is mounted on an inner housing element by means of a bearing in an unloaded state or during steering operation. The bearing comprises a cage and a spring element, wherein the cage has a ball recirculation channel with a plurality of spherical rolling elements arranged therein, and wherein the spring element forms a contact surface for the spherical rolling elements in contact with it. The cage further comprises a cage pocket with a cylindrical rolling element arranged therein, wherein a force acting on the inner and / or outer housing element during a crash is dissipated by the cylindrical rolling element rolling in line contact with the inner and outer housing elements.
[0034] The wording, according to which the outer housing element is slidably mounted on the inner housing element, is preferably to be understood as meaning that the inner housing element and outer housing element are slidably mounted relative to each other.
[0035] The invention will now be explained in more detail using preferred embodiments.
[0036] Fig. 1 shows a longitudinally adjustable steering column of a hand-wheel actuator with a steering wheel and several bearings,
[0037] Fig. 2 is a half-section view of an embodiment of a steering device in a first state, Fig. 3 is a half-section view of the embodiment of the steering device in a second state,
[0038] Fig. 4 shows a perspective view of a bearing for the embodiment of the steering device.
[0039] Fig. 5 shows a bottom view of the bearing shown in Figure 4,
[0040] Fig. 6 shows a top view of the bearing shown in Figures 4 and 5,
[0041] Fig. 7 shows a partial sectional view along section 5 - 5 of the bearing shown in Figure 6,
[0042] Fig. 8 shows an enlarged detail 9 of the bearing shown in Fig. 7,
[0043] Fig. 9 shows a sectional view along the cutting direction 7 7 of the bearing shown in Figure 6, and
[0044] Figs. 10, 11 show a perspective view of an outer housing element with bearings in two states.
[0045] Figure 1 shows a steering device 10 as part of a steer-by-wire steering system 12. The steering system comprises a steering wheel 2, a steering column 27, and several bearings 4. The steering wheel 2 is connected to an inner housing element 1, which is partially enclosed by an outer housing element 3. The outer housing element 3 is an outer housing, and the inner housing element 1 is an inner housing. One of the bearings 4 is arranged between the inner and outer housing elements 1 and 3. The bearing 4 serves to guide the housing elements 1 and 3 relative to each other without play, enabling longitudinal adjustment of the steering wheel 2 in a displacement direction 22. It is understood that displacement is also possible in the opposite direction to the depicted displacement direction 22. Figure 2 shows a steering device 10 in a first state. Identical or functionally equivalent elements are provided with the same reference numerals as in Figure 1.The first state comprises an unloaded state of the steering device 10 and / or steering operation of the steer-by-wire steering system 12. The outer housing element 3 is slidably mounted on the inner housing element 1 by means of the bearing 4. The bearing 4 has a cage 6 and a spring element 8. The cage 6 has a ball recirculation channel 34 and 36 in which a plurality of spherical rolling elements 14 are arranged. The spring element 8 forms a contact surface 18 for the spherical rolling elements 14 adjacent to it. The cage 6 also has a cage pocket 19 with a cylindrical rolling element 20 arranged therein.
[0046] In the state shown in Figure 2, the spherical rolling elements 14 are in contact with the inner housing element 1. When the outer housing element 3 is displaced relative to the inner housing element 1 in a displacement direction 22, the spherical rolling elements 14 roll along the inner housing element 1. The distance between a surface of the cylindrical rolling element 20 and a surface 21 of the inner housing element 1 is greater than zero when the cylindrical rolling element 20 is in contact with the surface of the outer housing element 3. Thus, in the state shown in Figure 2, the cylindrical rolling element 20 is mounted with clearance between the inner housing element 1 and the outer housing element 3. Therefore, only the spherical rolling elements 14 are in contact with the inner housing element 1 and roll on a surface of this housing element 1 during longitudinal adjustment of the steer-by-wire steering system 12. This results in low rolling friction.This means that the longitudinal adjustment of the steering wheel can be achieved manually with minimal effort or by means of a low-powered electric drive.
[0047] The roller-shaped rolling element 20 is configured as the first roller-shaped rolling element 30, which is arranged in the displacement direction 22 in front of the ball recirculation channel 34, 36. Furthermore, the roller-shaped rolling element 20 is configured as the second roller-shaped rolling element 40, which is arranged in the displacement direction 22 behind the ball recirculation channel 34, 36. In other words, the bearing 4 has two roller-shaped rolling elements 30 and 40. These roller-shaped rolling elements 30 and 40 are aligned parallel to each other in their longitudinal extent. It is possible, in principle, to omit either the first or the second roller-shaped rolling element 30 or 40.
[0048] The cage 6 also has two fastening elements 31 and 33. These serve to fasten the bearing 4 to the outer housing element 3 by means of the cage 6. For this purpose, the respective fastening element 31 or 33 is guided into a corresponding recess 28 or 29.
[0049] Figure 3 shows the steering device 10 in a second state. This second state occurs when, during a crash, a force 24 acts on the steer-by-wire steering system 12, for example, on the inner housing element 1. This force 24 accelerates the inner housing element 1. A radial force component 15, oriented transversely to the direction of displacement 22, causes the spherical rolling elements 14 to at least partially retract into the cage 6. This retraction is caused by the inner housing element 1 pressing the spherical rolling elements 14 into the cage 6. As a result, the cylindrical rolling element 20 comes into contact with the surface 21 of the inner housing element 1 and a surface 23 of the outer housing element 3.
[0050] The contact of the cylindrical rolling element 20 with the inner and outer housing elements 1 and 3 radially preloads the rolling element 20. This preload transmits the force 24 to the cage 6. This is due to a torque experienced by the cylindrical rolling element 20, which is generated by its contact with the accelerating housing element 1. The torque of the cylindrical rolling element 20, through its contact with the outer housing element 3, causes it to roll, which in turn results in a translational acceleration in the direction of displacement 22. This acceleration accelerates the cage 6 (the rolling element 20 pushes the cage 6 forward). The acceleration of the cage 6 generates a shear force that acts on the fastening elements 31 and 33.Depending on the force 24, in particular an axial force component 25, which is aligned parallel to the displacement direction 22, this leads to a shearing of the fastening elements 31 and 33. The roller-shaped rolling element 20 is therefore designed to dissipate the force 24 acting on the inner housing element 1 during a crash by rolling with line contact to the inner housing element 1 and outer housing element 3. The roller-shaped rolling element 20 forms a mechanical connection between the inner housing element 1 and the outer housing element 3. This connection bridges a mechanical force transmission, which, in the state shown in Figure 2, exists between the spherical rolling elements 14, the spring element 8, and the outer housing element 3. During dissipation, the bearing 4 displaces by half the displacement path of the housing element 1 moving in the displacement direction 22.
[0051] 3.
[0052] Figure 4 shows the bearing 4 shown in Figures 2 and 3 in a perspective view. The cage 6 has two cage pockets 19 in which the cylindrical rolling elements 30 and 40 are mounted as rolling elements 20. The fastening elements 31 and 33 of the cage 6 extend transversely to the direction of displacement 22 and transversely to an axis of rotation 32 of the cylindrical rolling element 20.
[0053] Figure 5 shows a bottom view of the bearing 4 shown in Figures 2 to 4. The cage 6 has two ball recirculation channels 34 and 36, in each of which a plurality of spherical rolling elements 14 are arranged. When the inner housing element 1 moves relative to the outer housing element 3, the spherical rolling elements roll along the ball recirculation channels 34 and 36.
[0054] The roller-shaped rolling element 30 is arranged in the displacement direction 22 in front of the ball recirculation channel 34 or 36 and the roller-shaped rolling element 40 is arranged in the displacement direction 22 behind the ball recirculation channel 34 or 36.
[0055] Figure 6 shows the bearing 4 shown in Figures 2 to 5 in a top view with cage 6, spring element 8 and roller-shaped rolling elements 30 and 40. Figure 7 shows the bearing 4 shown in Figures 2 to 6 in a partial sectional view according to the section direction 5-5 according to Figure 6 with cage 6, spring element 8 and roller-shaped rolling elements 30 and 40.
[0056] Figure 8 shows an enlargement of detail 9 shown in Figure 7 with roller-shaped rolling element 20, 30 and cage pocket 19 of the cage 6. Here, the roller-shaped rolling element 20 has a radius 50 and is arranged securely within the cage pocket 19.
[0057] Figure 9 shows a sectional view of the bearing 4 shown in Figures 2 to 7, corresponding to the section direction 7-7 as shown in Figure 6. The ball track 34 or 36 has a first section 38 or 39, in which the spherical rolling elements 14 can come into contact with the inner housing element 1 (not shown in Figure 9) in an unloaded state or during steering operation. In this first section 38 or 39, the spring element 8 forms a contact surface 44 or 45 for the spherical rolling elements 14. The ball track 34 or 36 has a second section 41 or 42, which is closed on the side facing the inner housing element 1, so that the rolling elements 14 guided therein do not intentionally bear against the inner housing element 1. The sub-areas 38 and 41 or 39 and 42 are connected to each other via deflection areas in such a way that the spherical rolling elements 14 are separated from the sub-area 38 or 42.39 can roll over the deflection areas into sub-area 41 or 42 (and vice versa).
[0058] Here, the radius 50 of the cylindrical rolling element 20 (see Figure 8) is larger than the radius 60 of the spherical rolling element 14 (see Figure 9).
[0059] Figures 10 and 11 show an embodiment of the outer housing element 3 in a perspective view. In Figure 10, several bearings 4 are shown in a state in which they are not attached to the outer housing element 3. In Figure 11, the bearings 4 are shown in a state in which they are attached to the outer housing element 3. For example, the fastening elements 31 extend into the recesses 28 of the outer housing element 3. (List of reference symbols)
[0060] inner housing element
[0061] steering wheel
[0062] outer housing element
[0063] Storage
[0064] Cutting direction
[0065] cage
[0066] Cutting direction
[0067] spring element
[0068] Detail
[0069] Steering device
[0070] Steer-by-wire steering system, spherical rolling elements, radial force component
[0071] Contact surface
[0072] Cage bag
[0073] , 30, 40 cylindrical rolling element surface
[0074] Direction of movement
[0075] surface
[0076] Power
[0077] Axial force component
[0078] steering column
[0079] , 29 Exclusion
[0080] axis of rotation
[0081] , 33 Fastening element
[0082] , 36 ball recirculation channel
[0083] , 39 first sub-area
[0084] , 42 second sub-area
[0085] 45 contact area
[0086] , 60 radius
Claims
1. Patent claims 1. Steering device (10) for a steer-by-wire steering system (12), comprising: - an inner housing element (1) and - a bearing (4) for the slidable mounting of an outer housing element (3) on the inner housing element (1), - wherein the bearing (4) has a cage (6) and a spring element (8), - wherein the cage (6) has a ball recirculation channel (34, 36) with a plurality of spherical rolling elements (14) arranged therein, - wherein the spring element (8) forms a contact surface (44, 45) for the rolling elements (14) adjacent to it, characterized by the fact that - the cage (6) has a cage pocket (19) with a roller-shaped rolling element (20, 30, 40) arranged therein and - the roller-shaped rolling element (20, 30, 40) is designed to dissipate a force (24) acting on the inner and / or outer housing element (1, 3) and / or a steering wheel (2) in a rolling manner with line contact to the inner and / or outer housing element (1, 3).
2. Steering device according to claim 1 , characterized by the fact that - a first roller-shaped rolling element (30) is arranged in a displacement direction (22) of the housing elements (1, 3) in front of the ball recirculation channel (34, 36); and / or - a second roller-shaped rolling element (40) is arranged in a displacement direction (22) of the housing elements (1, 3) behind the ball recirculation channel (34, 36).
3. Steering device according to claim 1 or 2, characterized in that the radius (50) of the cylindrical rolling element (20, 30, 40) is larger than the radius (60) of the spherical rolling elements (14).
4. Steering device according to one of claims 1 to 3, characterized by the fact that the roller-shaped rolling element (20, 30, 40) is mounted in an unloaded state of the steering device (10) or in a steering operation with a clearance between the inner housing element (1) and the outer housing element (3).
5. Steering device according to one of claims 1 to 4, characterized by the fact that the roller-shaped rolling elements (20, 30, 40) are designed to dissipate the force (24) acting on the inner and / or outer housing element (1, 3) and / or the steering wheel (2) in a crash by bridging a mechanical force transmission which exists in an unloaded state of the steering device (10) or in a steering operation between the inner housing element (1), the spherical rolling elements (14), the spring element (6) and the outer housing element (3).
6. Steering device according to one of claims 1 to 5, characterized by the fact that the spring element (8) is designed to be deformable in such a way that the spherical rolling elements (14) can be at least partially submerged into the cage (6) by the force (24) acting on the inner and / or outer housing element (1 , 3) and / or the steering wheel (2) during a crash, and the cylindrical rolling element (20, 30, 40) comes into contact with the surfaces of the inner and outer housing element (1, 3).
7. Steering device according to one of claims 1 to 6, characterized in that the cage (6) has a fastening element (31 , 33) for fastening the cage (6) to the outer housing element (3), wherein the fastening element (31, 33) is designed to be sheared off by a relative movement between the cage (6) and the outer housing element (3) when dissipating the force (24) acting on the housing element (1 , 3) and / or the steering wheel (2) in a crash.
8. Steering device according to claim 7, characterized by the fact that the fastening element (31 , 33) is arranged in a self-retaining manner on the outer housing element (3).
9. Steering device according to one of claims 1 to 8, characterized by the fact that the inner housing element (1) comprises an inner housing and the outer housing element (3) comprises an outer housing of a hand-wheel actuator.
10. Method for a steer-by-wire steering system (12) wherein - an outer housing element (3) is supported on an inner housing element (1) by means of a bearing (4) in an unloaded state or in a steering operation, - wherein the bearing (4) has a cage (6) and a spring element (8), - wherein the cage (6) has a ball recirculation channel (34, 36) with a plurality of spherical rolling elements (14) arranged therein, - wherein the spring element (8) forms a contact surface (44, 45) for the spherical rolling elements (14) adjacent to it, characterized by the fact that - the cage (6) has a cage pocket (19) with a roller-shaped rolling element (20, 30, 40) arranged therein and - a force (24) acting on the inner and / or outer housing element (1, 3) and / or a steering wheel (2) in a crash is dissipated by the roller-shaped rolling element (20, 30, 40) rolling in line contact with the inner and / or outer housing element (1, 3).