Patent Application
20190232995
This application claims priority to German Patent Application No. 10 2018 101 910.6 filed on Jan. 29, 2018, the entirety of which is incorporated by reference herein.
The disclosure relates to a method for unlocking a locking device of a superimposed steering system of a motor vehicle, to a method for operating a locking device of a superimposed steering system and to locking devices.
A superimposed steering system as part of a motor vehicle's active steering system produces a steering angle which is superimposed on a steering angle entered by a driver through actuation of the steering-wheel rim of the steering wheel. Accordingly, a rotational movement of a steering shaft connected to the steering wheel is made up of the steering angle entered by the driver and the steering angle produced by the superimposed steering system (in particular by a superimposed drive of the superimposed steering system). A superimposed steering system of this kind is known from WO 2007/009420 A1, for example.
Furthermore, a locking device for locking a superimposed steering system is known from WO 2012/120079 A1. Locking devices of this kind are used, in particular, to lock the superimposed steering system, e.g. for safety reasons in the event that the vehicle's electrical system should fail. When the superimposed locking system is in the locked state, direct mechanical access to the steering column, and therefore to the vehicle wheels, is guaranteed.
When the vehicle is started, the superimposed steering system is unlocked. The locking device comprises, in particular, a locking bolt which engages in the locked state with a component (e.g. in the form of a locking plate) of a superimposed transmission of the superimposed steering system. In order to unlock the superimposed steering system, the locking bolt is moved into an unlocking position in which it is no longer engaged with the component of the superimposed transmission. The movement of the locking bolt into the unlocking position may be accompanied by noises which arise, in particular, due to mechanical contact between the locking bolt and an abutment restricting movement and which are intensified by contact between the locking bolt and the component of the superimposed transmission when movement begins.
An object addressed by the proposed solution is that of preventing noise generation during the unlocking of a superimposed steering system in the most efficient way possible.
This object is solved by the provision of the method with features as described herein and also by the provision of the locking device having features as described herein.
According to a first aspect, a method is provided for unlocking a locking device of a superimposed steering system (in particular an active steering system) of a motor vehicle, wherein the locking device has a locking element which is located in a locking position in which it engages with a recess in a locking component of the locking device delimited by at least one abutment and thereby locks the superimposed steering system, wherein the method comprises the following steps:
This prepositioning of the locking component relative to the locking element means that noise generation that could be caused when unlocking the superimposed steering system through contact between the locking element and the abutment during the outward movement from the recess into the unlocking position, is avoided. The recess is, in particular, a depression or a through-opening in the locking component. It is conceivable for the locking component to have two abutments which delimit the recess on mutually opposite sides. Moreover, the locking component may, of course, also exhibit more than one recess of this kind.
The locking component may be a locking plate, for example, which is moved into the unlocking preparatory position by rotation. It is conceivable for the locking plate to be moved into the unlocking preparatory position by being rotated until it adopts an angle position that lies within a specified angle position range defining the unlocking preparatory position.
According to another embodiment, the locking plate is connected to a drive shaft of a superimposed transmission of the superimposed steering system, wherein the rotation of the locking plate into the unlocking preparatory position takes place by rotating the drive shaft with the help of a motor (in particular an electric motor). The drive shaft is, for example, a worm screw which meshes with a worm gear. The basic design of the superimposed transmission and the locking device (stopping device) is described in WO2010/115707 A1 or WO 2012/120079 A1, to which reference is hereby expressly made.
The rotation of the locking plate into the unlocking preparatory position takes place iteratively, in particular in the form of multiple rotational steps spaced apart from one another in time.
For example, the motor is activated for a first period of time, wherein the angle position of the locking plate is then determined and checked to see whether it lies within the angle position range, wherein the motor is activated for a second period of time if the angle position determined lies outside the angle position range.
During the first and second period of time, for example, the activated motor exerts a first or second torque (in particular in the form of a torque surge in each case) on the drive shaft, wherein the second torque (the magnitude of the second torque) depends on the angle position determined after the first period of time. For example, a second torque is applied, the magnitude of which is greater than the magnitude of the first torque when, after the first period of time, the difference between the angle position of the locking plate and the angle position range is greater than a predetermined maximum difference. It is also conceivable for the magnitude of the second torque to be smaller than the magnitude of the first torque if the difference between the angle position of the locking plate after the first period of time and the angle position range is smaller than a predetermined minimum difference.
According to a second aspect, the embodiment relates to a method for operating a locking device of a superimposed steering system of a motor vehicle, in particular for use in a method according to the first aspect, wherein the locking device has a locking element which engages in a locking position with a recess in a locking component of the locking device delimited by at least one abutment, comprising the steps:
By producing a tensioning state and determining a force and/or a torque which is required to relax the tensioning state, a movement resistance within the superimposed transmission created, in particular, due to friction between components of the superimposed transmission (for example between a worm screw and a worm wheel) can be determined. In this way, a minimum torque can be determined, for example, which must be exerted in order to start a component (for example the aforementioned worm screw) of the superimposed transmission rotating.
The force and/or torque at which the tensioning state is relaxed is determined, for example, by establishing a force and/or a torque at which the abutment is removed from the locking element.
As already mentioned above in relation to the first aspect, the component of the superimposed transmission is, for example, a drive shaft (in particular in the form of a worm screw) that is movable with the help of a motor and the locking component is a locking plate connected to the drive shaft. With the help of the method as described herein the minimum torque required in order to start the locking plate rotating can, in particular, be determined.
According to another embodiment, at least during application of the increasing force and/or the increasing torque on the locking component, a variable dependent on the speed of the locking component and/or the component of the superimposed transmission or the speed (of the locking component and/or the component of the superimposed transmission) itself is determined, wherein the force exerted at a point in time at which this variable or the speed reaches a predetermined minimum value or the torque exerted at this point in time is determined as the force or the torque at which the tensioning state is relaxed. For example, the determined variable is a speed or an angular velocity of the aforementioned motor via which the drive shaft is driven.
Another variant envisages that after the force and/or torque has been determined, the method described above according to the first aspect is carried out, wherein the movement of the locking component into the unlocking preparatory position takes place at least initially by exerting a force or torque on the locking component which at least corresponds to the force or torque which was determined using the method according to the second aspect.
The force determined according to the second aspect or the torque determined in this manner is therefore used to move the locking component into the unlocking preparatory position, as a result of which, for example, the most instantaneous movement possible of the locking component and therefore the quickest possible unlocking of the locking device can take place. It is conceivable for the force determined with the help of the method according to the second aspect or the torque determined as the starting value for the iterative movement of the locking component into the unlocking preparatory position, as described above, to be used.
Furthermore, it is conceivable for the force determined according to the second aspect and/or the torque determined for controlling processes of the superimposed steering system to be used which are not related to the unlocking of the locking device.
It is pointed out that the embodiments of the method described above can naturally also be used similarly according to the first aspect for development of the method according to the second aspect. Furthermore, the control of the locking component and/or of the locking element required in order to implement the method as described herein can take place with the help of a correspondingly programmed unit of the vehicle (in particular the vehicle's ECU).
The disclosure further relates to a locking device for a superimposed steering system of a motor vehicle, in particular for implementing the method according to the first aspect, having
Moreover, the disclosure relates to a locking device for a superimposed steering system of a motor vehicle, in particular for implementing the method according to the second aspect, having
The components of the locking devices as described herein, in particular the locking element, the locking component and/or the components of the superimposed transmission, may of course be configured according to the exemplary embodiments explained above in connection with the method in accordance with the first and second aspects.
The disclosure also relates to a superimposed steering system with a locking device as described herein and also a motor vehicle with a superimposed steering system of this kind.
The embodiments are explained in greater detail below with the help of exemplary embodiments with reference to the figures.
The superimposed drive 1 furthermore has a locking device 2 for locking the superimposed steering system. The locking device 2 comprises a locking element in the form of a locking bolt 21 which, which the help of a spring, can be moved from a starting position into the locking position shown in
The locking plate 22 comprises a plurality of recesses 221 which each have a first and second depression in the form of a first and second pocket 222, 223 and also a transitional region 224 with a shallower depth located between the first and the second pockets 222, 223. The recesses 221 are each delimited by a side wall 2221 of the first pocket 222 and a side wall 2231 of the second pocket 223, wherein the pockets 222, 223 are delimited on their sides opposite the side walls 2221, 2231 by side walls 2222, 2232. The side walls 2221, 2231, 2222, 2232 each create an abutment 2220, 2230, 2223, 2233 for the locking bolt 21. In particular, in the locking position during rotation in the rotational direction of the worm screw 12 indicated in
It is pointed out that
In order to implement the method, the locking bolt 21 is initially moved into the recess 221 in the locking plate 22. For example, following movement into the recess 221, the locking bolt 21 is located the transitional region 224 thereof (
It is pointed out that the preceding and following explanations in relation to a particular rotational direction of the locking plate 22 also apply similarly to the opposite rotational direction.
The motor torque MM is then increased at time T2 in order to produce a tensioning state in the superimposed transmission (in particular between the worm screw and the worm wheel). In this case, a motor torque MM profile of this kind is used to produce a tensioning state which is maintained even with a subsequent lowering of the motor torque MM up to time T3 and a subsequent holding of the motor torque MM up to time T4. In particular, the locking bolt 21 also remains in contact with the abutment 2220 up to time T4. Accordingly, the motor angular velocity MWG also remains at least approximately at zero. The reduction in the motor torque at time T3 is indicated in
Following the holding phase, i.e. after time T4, the motor is activated in such a manner that a torque opposing the original direction of rotation R is exerted on the worm screw. The tensioning state of the superimposed transmission and also the contact between the locking bolt 21 and the abutment 2220 are still maintained to begin with, however, even after this opposing torque has been exerted. Only when the exerted torque reaches a required minimum torque (at time T5) does the tensioning state relax and the locking plate 22 is moved relative to the locking bolt 21, so that the locking bolt 21 is removed from the abutment 2220 (
At time T5 the motor angular velocity MWG also changes accordingly, wherein the magnitude of the motor angular velocity MWG passes through a minimum and at a time at which the right abutment 2230 comes into contact with the locking bolt 21 it returns to zero. By detecting the motor torque at time T5, the minimum torque necessary in the current state of the superimposed transmission in order to bring about an initial turning (i.e. start of rotation) of the locking plate 22 can be determined. It is also conceivable for the torque to be used to start the turning of the locking plate 22 not to be determined exactly at time T5, but at a time at which the magnitude of the motor angular velocity MWG or the speed of the motor reaches a predefinable threshold value.
It is conceivable for the method according to the embodiment described according to
The gradual rotation of the locking plate 22 takes place through torque surges exerted at intervals and illustrated in
The magnitude of the torque applied in each case depends on the motor angle, for example, in other words the angular position of the locking plate 22. In the present case, the motor angle is located outside the predetermined target angle position range ZWB depicted by the shaded area in
The magnitude of the respective torque during the torque surges is therefore increased or reduced depending on the angle position of the locking plate 22 achieved with the preceding torque surge, wherein torque surges are applied until the locking plate 22 is located in the predetermined angle position range ZWB and the locking bolt 21 is therefore in a target zone (characterized by vertical arrows in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2018 101 910.6 | Jan 2018 | DE | national |
