Patent Application
20250018997
The disclosure relates to an actuator for an axle steering system of a vehicle, comprising a push rod which is movable longitudinally within a housing, wherein the push rod has a rotation lock. The disclosure further relates to an axle steering system having such an actuator and to a vehicle comprising such an axle steering system.
DE 10 2018 130 228 B3 discloses an actuator for a rear axle steering system of a vehicle, comprising a push rod which is movable longitudinally within a housing, wherein the push rod has a rotation lock with a guide element which is guided in the axial direction in a single-part or multi-part slide rail arranged on the housing, wherein an elastomer ring is arranged between the slide rail and the housing.
The object of the present disclosure is to propose an alternative actuator for an axle steering system of a vehicle. According to the disclosure, this object is achieved by an actuator having the features described herein and shown in the attached figures.
An actuator according to the disclosure for an axle steering system of a vehicle comprises a push rod which is movable longitudinally within a housing. A target holder for a target is fastened releasably on the push rod, and the target is designed to interact with a stationary sensor arrangement. The target holder has a base part for receiving the target and at least one first snap-fit contour integrally formed on the base part that engages at least partially around the push rod and has a first snap-fit arm and a second snap-fit arm. The essential advantage of this arrangement is that there is no need to additionally screw the target to the push rod.
The actuator is provided for setting a steering angle of vehicle wheels that are operatively connected to the actuator on a rear axle of the vehicle by axially displacing the push rod relative to the housing. This initiates or supports cornering of the vehicle, for example. For this purpose, the push rod can have at least one fork connection with a fork element at its free ends, on which the respective vehicle wheel is received at least indirectly. The push rod can be designed in one or more parts and has a threaded spindle connected to it in one or more parts and arranged concentrically therewith. The push rod can be formed in at least two parts, wherein the two push rod segments can be connected to one another via a slide. The push rod segments can be screwed into the slide, for example. This can simplify the mounting of the actuator.
A drive unit, for example in the form of an electric motor, is provided to drive an axially non-displaceable, rotationally driven threaded nut of the actuator. The threaded nut is operatively connected to a threaded spindle. The threaded nut is arranged such that it can rotate in relation to the housing and is mounted and supported on the housing accordingly. The threaded spindle is arranged at least indirectly on the push rod, and the threaded spindle together with the push rod, and possibly the slide, is moved longitudinally or set into a longitudinal movement relative to the housing or the threaded nut by a rotation of the threaded nut. Consequently, the threaded spindle and the threaded nut form a screw drive, and the rotary drive of the threaded nut at least indirectly causes a linear adjusting movement of the push rod for setting the steering angle. Furthermore, the drive unit can comprise a transmission device which is designed, for example, as a belt transmission and is operatively connected to the threaded nut.
The target fastened on the push rod interacts with the sensor arrangement, which can be fastened to the housing. The target is movable with the push rod relative to the stationary, in particular fixed to the housing, sensor arrangement, in order to be able to determine, in particular, an axial position of the push rod relative to the housing. The sensor arrangement comprises a sensor cover which is fastened when it is mounted on the housing of the axle steering system. The target is supported on the sensor cover in the circumferential direction and guided by it.
In the region of the target, the push rod can be designed as a shaft, in particular with an essentially circular cross-section. The snap-fit arms of the respective snap-fit contour form an essentially C-shaped, concave inner surface that is formed in a manner complementary to an outer surface of the push rod. The snap-fit contour forms a partial ring surface with the snap-fit arms, the circumference of which is in any case larger than half the circumference of the push rod, so that the snap-fit arms snap into place when the target holder is mounted on the push rod and thus create a form-fitting connection with the push rod. This prevents radial detachment of the target holder from the push rod.
At least one of the snap-fit arms, in an example embodiment, both snap-fit arms, are elastically deformable in order to implement the snap-fit mounting of the target holder on the push rod. After mounting the target holder, the snap-fit arms engage around the push rod at least partially, in particular around more than half the circumference of the push rod, and thus secure the target holder on the push rod in a radial direction or support the target holder radially on the push rod.
The target holder can comprise a second snap-fit contour axially spaced apart from the first snap-fit contour and having a first snap-fit arm and a second snap-fit arm. The two snap-fit contours can be identically designed, wherein the push rod is thus engaged around at two axial positions by the snap-fit contours of the target holder. By providing two or more axially spaced apart snap-fit contours, tilting of the target holder relative to the push rod can be prevented. In particular, the target holder is prevented from pitching. Thus, the target holder is arranged on the push rod in a more stable manner.
The disclosure includes the technical teaching that the push rod has a radial tapering for radially receiving the respective snap-fit contour. In other words, the push rod has a radial recess in the region of the target holder. This secures the target holder on the push rod in the axial direction. The target holder is therefore supported axially on the push rod.
The respective snap-fit contour secures the target holder at least against radial movement relative to the push rod. The elastic properties of the respective snap-fit contour or the snap-fit arms are selected such that unintentional detachment of the target holder from the push rod in the radial direction is prevented. Consequently, the snap-fit arms of the respective snap-fit contour are designed to be so elastic or soft that the target holder can be mounted on the push rod, and so rigid that the target holder cannot be unintentionally detached from the push rod.
In order to prevent the target holder from rotating relative to the push rod, at least one resiliently deformable spring tab is formed, in each case, on the base part on the side surfaces guided by the housing, which spring tab is designed to secure the target holder against rotation relative to the sensor arrangement. In other words, at least one spring tab each is formed on two opposite side surfaces on the base part. The side surfaces of the base part extend essentially parallel to the direction of movement or longitudinal direction of the push rod. The spring tabs support the target holder in the circumferential direction on the housing and ensure longitudinal guidance of the target holder on the sensor arrangement. The target holder is therefore held in a rotational normal position by the spring tabs. This improves the measuring accuracy of the sensor arrangement. Consequently, the susceptibility of the sensor arrangement to measurement errors is reduced. The spring tabs further compensate for manufacturing tolerances on the sensor arrangement and/or target holder. In particular, the stiffness of the spring tabs is selected such that their reaction force is greater than the resulting torque from the torsion of the push rod. This ensures that the target holder always remains in its rotational neutral position.
The spring tabs have resilient properties. The term “resilient” means here that the material of the respective compression spring behaves according to Hooke's law in its working range and therefore has a spring constant. This is a material property in which a deformation or deflection caused by an external force results in an immediate rebound of the respective spring tabs when the external force is removed. The same applies to the snap-fit arms of the respective snap-fit contour.
The sensor arrangement can have a receptacle into which the base part with the target projects at least partially. In an example embodiment, the sensor cover of the sensor arrangement has the receptacle. In a further aspect, the spring tabs are arranged within the space formed by the receptacle of the sensor arrangement and are supported laterally on the inner wall of the sensor arrangement in relation to the direction of movement of the push rod in order to implement the rotation lock of the target holder.
According to an alternative exemplary embodiment, the spring tabs are designed and formed on the base part such that they project from the space defined by the receptacle of the sensor arrangement in the direction of the snap-fit contour of the target holder. In this sense, the spring tabs can be designed such that they pre-position the target holder relative to the housing before the sensor arrangement is mounted on the housing. When mounting the actuator, after mounting the push rod in the housing, the target holder is mounted on the push rod as described above by snapping the snap-fit arms of the respective snap-fit contour onto the push rod. In the process, the spring tabs implement an intermediate positioning of the target holder relative to the push rod and relative to the housing and pre-center the target holder until the sensor arrangement is mounted.
The spring tabs can also be designed such that they guide the target holder on the sensor arrangement and do not come into contact with the housing after the sensor arrangement has been mounted on the housing. Consequently, once the sensor arrangement has been mounted, an intermediate positioning of the target holder on the housing is no longer necessary, wherein the target holder is guided and secured against rotation exclusively via the spring tabs that are supported on the sensor arrangement after the sensor arrangement has been mounted. The sections with which the spring tabs previously came into contact with the housing as part of the intermediate positioning no longer come into contact with the housing. When the sensor arrangement is mounted, the spring tabs continue to deform elastically and are pressed inwards in such a way that they are only supported on the sensor arrangement, in particular on the inner wall of the receptacle of the sensor arrangement, and no longer on the housing.
The term “at least indirectly” means here that two components are connected to one another via at least one other component that is arranged between the two components, or are immediately and thus directly connected to one another. In other words, the target holder can be arranged on the push rod via an intermediate component.
The target holder can be made of plastic. In particular, the target holder, i.e., the base part and the respective snap-fit contour, are manufactured integrally by means of injection molding.
Such an actuator can be used in an axle steering system of a vehicle according to the disclosure, in particular in a front axle steering system and/or a rear axle steering system. The vehicle can have multiple front or rear axles, wherein one or more of the front or rear axles has/have a respective axle steering system with an actuator of the previously described type.
Further measures improving the disclosure are described in more detail below together with the description of two exemplary embodiments of the disclosure with reference to the figures, wherein identical or similar components are marked with the same reference sign. In the drawings:
The target holder 4 is fastened to the radial tapering 15 of the push rod 2, so that the target holder 4 is additionally secured in the axial direction. In this regard, the target holder 4 comes into axial contact with the push rod 2 in both axial directions with the first snap-fit contour 8 or the second snap-fit contour 9.
As
When mounting the sensor arrangement 6 on the housing 3, the spring tabs 17, 18 are pressed further inwards by the sensor cover. Consequently, the spring tabs 17, 18 continue to deform elastically in such a way that, after the sensor arrangement 6 has been mounted on the housing 3, they only come into contact with the inner wall in the receptacle 19 of the sensor arrangement 6 and no longer with the housing 3. This ensures low-friction operation of the actuator 1, in particular low-friction guidance of the target holder within the housing 3 or along the sensor arrangement 6.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 131 245.0 | Nov 2021 | DE | national |
This application is the U.S. National Phase of PCT Application No. PCT/DE2022/100813 filed on Nov. 4, 2022, which claims priority to DE 10 2021 131 245.0 filed on Nov. 29, 2021, the entire disclosures of which are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2022/100813 | 11/4/2022 | WO |
