End stop in a steering system for a motor vehicle

Abstract

Steer-by-wire steering system for a motor vehicle, with a steering column (1), comprising a steering handle, a housing (2), a sensor system for measuring the angle of rotation, a steering shaft (6) and an end stop for limiting the rotational movements of the steering handle, wherein the end stop comprises a gear (8) which is connected to the steering shaft (6) and which meshes with an internally toothed ring gear (7), wherein the internally toothed ring gear (7) has a stop (9) on its outer surface (12); wherein the housing (2) has a counter-stop (10); wherein the rotational movement of the steering handle is limited by the end stop in both directions of rotation when the stop (9) touches the counter-stop (10).

Description

The present invention relates to a steer-by-wire steering system of a motor vehicle having an end stop.Prior ArtIn an electric power steering system according to the steer-by-wire principle, there is no longer any mechanical connection between the steering wheel and the steering gear. The steering rack actuator is an assembly for adjusting the wheels of a vehicle. Steering commands from a control unit are transmitted to an electric motor, which displaces the toothed rack via a steering gear. The rack adjusts the steering angle at the wheels in the usual manner via the tie rods.The steering wheel actuator is the upper assembly in a steer-by-wire steering system and comprises the steering wheel, a sensor system for measuring the angle of rotation and a force feedback motor which simulates steering forces in order to give the driver feedback from the steering forces. The determined data on the torque and angle of rotation are transmitted to a control unit which then controls the steering rack actuator.The steering wheel rotations in conventional steering systems were limited by the lifting movement of the rack. Due to the lack of a mechanical connection between the two assemblies in a steer-by-wire system, it would be possible to turn the steering wheel infinitely in one direction. However, this would damage the coil spring on the steering spindle. In addition, the driver requires feedback about the maximum steering angle achieved.Therefore, the steering wheel actuator still comprises mechanical end stops in both steering directions.DE 10 2015 120 207 A1 discloses a steering device for a motor vehicle, wherein a transmission device has a rotatably arranged second gearwheel which meshes with the first gearwheel and an internal toothing of a ring gear and is movable along the ring gear upon a rotation of a steering spindle, wherein the transmission device has a limiting device for limiting a rotational movement of the steering spindle, which limiting device is designed to limit a movement of the second gearwheel along the ring gear.It is the object of the invention to provide an alternative end stop which is made more compact.This object is achieved by the steering system for a motor vehicle having the features of claim 1.Disclosure of the InventionThe present invention provides a steer-by-wire steering system having a steering column, wherein the steering column has a steering handle which serves for inputting the steering request of the driver, a housing, a sensor system for measuring the angle of rotation and an end stop for limiting the rotational movements of the steering handle.The end stop comprises a gear wheel which is fastened on a steering shaft and an internally toothed ring gear, wherein the gear wheel is arranged within the ring gear wheel and drives it.One concept of the present invention is that the ring gear is rotatably guided in a ring, which can be part of the housing. The ring gear has a stop on its outer surface. The housing or the ring has a counterstop, so that after one rotation of the ring gear, the rotational movement is limited in both rotational directions.The difference in size of the two gears results in a transmission ratio, whereby the small gear has a greater angular speed than the larger ring gear. As a result, the small gearwheel can make more revolutions than the ring gearwheel, depending on the size difference, by virtue of design and corresponding transmission ratio.The proposed end stop advantageously has a small overall size and lower material costs than comparable solutions.The steering column can be adjustable, whereby the steering shaft consists of two steering shafts. The first steering shaft, which is mounted in the crash tube, carries the steering handle. A second steering shaft is co-rotated via a sliding unit. The small gearwheel is then fastened to the second steering shaft, which gearwheel meshes with the internal toothing of the ring gearwheel.Furthermore, the steering column can also comprise a force feedback device in order to simulate steering forces corresponding to the driver.The housing part which has the ring for guiding the ring gear can be part of the force feedback actuator or part of the steering column housing. On the ring or on the housing, the counterstop is arranged, which restricts the rotational movement of the ring gear. By defining the position and size of the two stops, the entire steering angle and the required robustness can be established.The gearwheel and the ring gear have involute toothing, as a result of which very good acoustic properties are also obtained.The ring gear can be embodied in multiple parts. The region of the ring gear where the stop is arranged can be made of a more highly resistant material, such as steel, in order to support correspondingly high forces of the end stop, while other regions of the ring gear which only assume the function of the rotational movement and of the mounting in the housing can be made of a plastic.An embodiment will now be described with reference to the figures. The following are shown: FIG. 1 shows a steering column of a steer-by-wire steering system FIG. 2 shows the end stop according to the invention in the assembled state FIG. 3 shows the end stop according to the invention with its individual parts in a first view FIG. 4 shows the end stop according to the invention with its individual parts in a second viewFIG. 1 shows the steering column 1 of a steer-by-wire steering system. The steering column 1 comprises a housing 2, in which a crash tube 4 is mounted. On one side of the steering column 1, the actuator 3 of a force feedback device is arranged. On the other side of the steering column is the steering handle (not shown) which is seated on a steering shaft. The steering shaft consists of two steering shafts (5, 6). The first steering shaft 5 carries the steering handle and rotates the second steering shaft 6 via a sliding joint.Furthermore, FIG. 1 shows that the end stop is arranged on the second steering shaft 6, wherein the end stop is located in the lower part of the housing 2.Furthermore (and not designated in detail) components of the steering column can be seen in FIG. 1, which serve for fastening to the vehicle body and for height and inclination adjustment.FIG. 2 shows the end stop according to the invention in the assembled state. The second steering shaft 6 carries the gearwheel 8, which has an external toothing. Furthermore, a part of the housing 2 can be seen. The housing 2 has a ring 11 which supports and guides the ring gear 7 in a rotationally positive manner. The mounting of the ring gear 7 in the ring 11 is designed as a plain bearing. The small gearwheel 8 meshes with the internal toothing of the ring gear 7. the ring 11 can be formed directly on the housing 2; for example, the housing 2 and the ring 11 can be a cast part. However, it is also possible to design the ring as a separate component.FIG. 3 shows the individual components of the end stop. The ring gear 7 has a stop 9 on its outer surface 12.FIG. 4 again shows the individual components of the end stop in a further view. The ring 11 of the housing 2 shows the counterstop 10. The counterstop 10 can be fastened to the ring 11 or to the wall.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2015 120 207 A1

[0006]

Claims

Steer-by-wire steering system for a motor vehicle, having a steering column (1) comprising a steering handle, a housing (2), a sensor system for measuring the angle of rotation, a steering shaft (6) and an end stop for limiting the rotational movements of the steering handle, wherein the end stop comprises a gearwheel (8) which is connected to the steering shaft (6) and which meshes with an internally toothed ring gearwheel (7), characterized in that the internally toothed ring gearwheel (7) has a stop (9) on its outer surface (12); in that the housing (2) has a counterstop (10); wherein the rotational movement of the steering handle is limited by the end stop in both rotational directions when the stop (9) touches the counterstop (10).Steer-by-wire steering system according to Claim 1, characterized in that a ring (11) is fastened to the housing (2), which ring supports the ring gear (7) in a rotationally positive manner.Steer-by-wire steering system according to Claim 2, characterized in that the bearing arrangement of the ring gear (7) in the ring (11) is a plain bearing arrangement.Steer-by-wire steering system according to one of Claims 1 to 3, characterized in that the ring gear (7) is of multipart design, wherein at least the region at the stop (9) is produced from steel and wherein the regions of the plain bearing are produced from a plastic.Steer-by-wire steering system according to one of Claims 1 to 4, characterized in that the gearwheel (8) and the ring gearwheel (7) have involute toothing.

Images