WO2017182502A1

WO2017182502A1 - Steer-by-wire steering device for motor vehicles

Info

Publication number: WO2017182502A1
Application number: PCT/EP2017/059247
Authority: WO
Inventors: Kristof Polmans
Original assignee: Thyssenkrupp Presta Ag; Thyssenkrupp Ag
Priority date: 2016-04-19
Filing date: 2017-04-19
Publication date: 2017-10-26
Also published as: DE102016206610A1

Abstract

The invention relates to a steer-by-wire steering device for motor vehicles, comprising a steering shaft (51), which is connected at one end to a steering wheel (52) and on which an electric motor (6) acts, preferably by means of a reduction gearing (10, 11), which electric motor produces steering torques, which give the driver feedback about the forces acting on the steered vehicle wheels (46), and comprising a locking device (12) arranged on the steering shaft (51) or the motor shaft (9) of the electric motor (6) for blocking the rotation of the steering shaft (51), is improved with regard to a simple and compact construction of the locking device (12) in that the steering shaft (51) or the motor shaft (9) is connected to a detent star wheel (15), which has detent grooves (16) distributed over the periphery thereof, and that a detent device is attached to a housing (19) that supports the steering shaft (51) or the motor shaft (9), which detent device has a detent bolt (14), which can be locked into a detent groove (16) of the detent star wheel (15) from outside by means of an actuator (13).

Description

Steer-by-wire steering device for motor vehicles

The invention relates to a steer-by-wire steering device for

Motor vehicles, with a steering shaft, which at one end with a

Steering wheel is connected and acting on an electric motor and

Generates steering torque, which gives the driver feedback about the forces acting on the steered vehicle wheels forces, and arranged with one on the steering shaft or the motor shaft of the electric motor

Locking device for blocking the rotation of the steering shaft.

Steer-by-wire steering systems are characterized by the fact that there is no mechanical connection between the steering wheel and the steerable wheels. However, in order to give the driver a feedback on the condition of the road and other environmental influences, such as wind, weather, road conditions, etc., feedback actuators are used. Such a feedback actuator, too

Called manual torque, contributes to the steering shaft, which is connected to the steering wheel, a torque. Usually, the feedback actuator to an electric motor which is coupled via a worm gear with the steering shaft. The torque introduced into the steering shaft and the steering wheel by means of the feedback actuator gives the driver a driving experience that is familiar from purely mechanical steering systems. He receives feedback on the forces acting on the steered wheels.

An important part of the steering feeling is the feedback about a strongly increasing moment in certain steering situation. These

Situations occur especially in two steering maneuvers. If the steered wheel is pushed off the curb (curb push off), an increase of the steering torque on the steering wheel could lead to mechanical

Damage to the steering system, such as the Hand torque regulator, lead. The same applies if the

Steering gear has reached the maximum steering angle and on

reached mechanical stop. In both cases, the driver needs the feeling of strong resistance to further rotation of the steering wheel in this direction and thus a mechanical

Damage to the hand-torque actuator should be avoided. Consequently, when one of these situations occurs, the feedback actuator would have to apply a very high counter-torque. This is possible only with very strong electric motors, which would be associated with high costs. Instead of designing the electric motor particularly strong, alternatively, the steering column can be blocked or locked. Corresponding locking or blocking devices are known.

DE 60 303 081 T2 discloses several different types of

Locking mechanisms for a manual torque controller, which either a magnetorheological stop on the steering shaft, a

mechanically adjustable mechanical stop or a

Use pawl mechanism. In the known

Pawl mechanism, two gear segments interact with two pawls. The two gear segments cause blocking of the steering shaft in each case only in one direction when the associated pawl is triggered. A disadvantage of this solution is the complex and space-consuming construction.

A locking mechanism is also known from DE 10 2014 009 517 B3, in which two solenoid-actuated locking bolts act on two toothed wheels, each of which controls the rotation of the steering shaft only in one

Rotation blocked. In this case, the locking bolt are bevelled at their coming into engagement with the gear end and the gears have corresponding beveled teeth, so that blocking only in one direction is possible, while rotation of the steering shaft in the opposite direction leads to a pushing back of the locking bolt by the corresponding tooth of the gear. These too

Blocking device is complex and space-consuming.

The object of the invention is to provide a steer-by-wire steering device for motor vehicles with a feedback actuator, which has a simple design and compact locking device for the steering operation.

The solution according to the invention provides that the steering shaft or the motor shaft is connected to a detent star, which has distributed over its circumference arranged locking grooves, and that at one

Steering shaft or the motor shaft overlapping housing a locking device is mounted, which has a locking pin which can be latched by means of an actuator from the outside into a locking groove of the locking star in the steering operation. The locking device according to the invention requires only a solenoid-actuated locking pin and a snap-in star and can thus block both directions of rotation. It is therefore simple and

inexpensive to produce.

Under the steering operation is that operating state to understand in which the driver enters a steering command in the form of a steering torque in the steering shaft to initiate a change in direction of the vehicle. This takes place in the normal and intended use of the vehicle and not in the parked or parked and locked state of the vehicle.

Preferably, the locking device with Raststern and

Detent pin arranged on the motor shaft of the electric motor. Here occur due to the reduction gear lower torques than directly on the steering shaft, so that the locking device can be made weaker and thus more compact. In a preferred embodiment, the actuator comprises the

Detent device a solenoid (solenoid), in which a magnetic detent pin is arranged to be longitudinally displaceable in the direction of the detent star, so that it engages with its star facing the detent star in a latching groove of the detent star with electrically energized solenoid. The actuator is particularly simple in this embodiment.

When the detent pin is connected at its end remote from the detent star with a movable end of a spring, preferably a coil spring, whose fixed end is supported on the solenoid, so that the spring pulls the detent pin with electrically switched off solenoid out of the detent, it needs none other measures for releasing the locking device such as in the above-described prior art. By the measure that the side walls of the Rastnuten of the

Raststerns are aligned parallel to the axis of the locking bolt, resulting in the action of high steering forces on the steering wheel by the driver no force components that would push the locking pin out of the locking groove out. Therefore, the locking connection is maintained even under heavy use.

The invention is further improved by the measure that

operatively between the Raststern and the steering shaft or

Motor shaft is arranged an elastic body, which allows a small rotation of the steering shaft with latched locking pin, which builds up an increasing counter torque. This measure serves the purpose that the generated by blocking the steering shaft holding torque does not build up abruptly. Due to the elastic

Properties of the elastic body, the holding torque is built over a limited angle of rotation and thus generates a progressive torque increase on the steering wheel, which corresponds to the natural steering feel in a steering system with a mechanical connection.

The elastic body may consist in practice of an elastomeric ring or a torsion spring or a tolerance ring.

Embodiments of the invention are explained in more detail with reference to the drawing and the figures show in detail:

Figure 1: a schematic diagram of a steer-by-wire steering system with

Feedback actuator; Figure 2: a partially sectioned view of the drive of

Feedback actuator with inventive

Locking device;

Figure 3: a steering column as in Figures 1 and 2 in longitudinal section;

Figure 4: a section through an inventive

Locking device with a tolerance ring as an elastic body between the motor shaft and Raststern;

Figure 5: A locking device in a representation as in FIG

3, but with an elastomeric ring as an elastic body;

Figure 6: the locking device of Figure 5 with engaged

Indexing plungers;

Figure 7: the locking device of Figure 6 with slightly deformed

Elastomeric ring; Figure 8: the locking device of Figure 6 with strong

deformed elastomeric ring due to a large steering torque;

FIG. 9 shows a diagram of the generated steering torque (M) in FIG

Dependence on the angle of rotation (Δ Φ) of the steering wheel

Figure 10: a further embodiment of the invention, in which the

Locking device acts directly on the steering shaft;

Figure 1 1: a partial sectional view of the embodiment of

FIG. 1 shows a steer-by-wire steering system for a motor vehicle with a steering wheel assembly 2 and a steering operation 42

Steering assembly 2 includes a steering shaft 51 which carries at one end a steering wheel 52 and at the other end a rotary encoder 7 for the electronic control of the electric steering operation 42nd

is provided. About a connecting cable 3, the steering assembly 2 is connected to the steering operation 42. This comprises a steering housing 4 with a steering motor 41 which drives a pinion 43, which in turn is in engagement with a rack 44 which acts on two tie rods 45, with which the vehicle wheels 46 can be pivoted. In the steering housing 4 is not shown Drehmomentaufnehmer

housed, which measures the torque required for the pivoting of the vehicle wheels 46 and forwards to the steering wheel assembly 2.

The steering wheel assembly 2 also includes a

Torque generating unit 8, which has an electric motor 6, the motor shaft 9 acts on a gear shaft 10 with worm wheel. The transmission shaft 10 is with its worm in engagement with a Gear 1 1, which is mounted on the steering shaft 51. Depending on the torque sensor of the steering operation 42 predetermined

Torque, the electric motor 6 of the torque generating unit 8 is driven, which initiates via the transmission shaft 10 with worm wheel and the gear 1 1, a corresponding torque in the steering shaft 51. In this case, the transmission shaft 10, which comprises a worm, together with the worm wheel designed as a large gear 1 1 as a reduction gear, which significantly boosts the torques generated by the electric motor 6. To counteract initiated by the driver via the steering wheel 42 in the steering shaft 51 strong torque, which generates an end stop when full steering of the steering wheel or abutment of the vehicle wheels 46, for example on a curb in conventional mechanical steering systems, the strength of

Electric motor 6 is not enough. For this purpose, therefore, a locking device 12 is provided, which is adjacent to

Motor shaft 9 arranged solenoid 13, in which a magnetic detent pin 14 is arranged longitudinally displaceable. Arranged around the motor shaft 9 is a detent star 15, which is connected to the motor shaft 9 substantially non-rotatably (see below, however, "elastic body"). When the solenoid 13 is switched on, it presses the magnetic detent pin 14 in the direction of the detent star 15, until the latching bolt 14 engages in a latching groove 16 of the latching star 15. This occurs in the steering operation of the steering system The latched state is illustrated, for example, in Figures 4 and 6 to 8. It can be seen that the latching star 15 facing the end 17 of the locking bolt 14 of the locking groove 16th

is recorded. In this case, the outer walls of the end 17 of the locking bolt 14 and the side walls 18 of the locking groove 16 are parallel aligned with each other and to the longitudinal axis of the locking bolt 14. This can best be seen in FIGS. 7 and 8. By the aforementioned orientation, the locking pin 14 can not be pushed out of the locking groove 16, even if strong on the steering shaft 51

Acting torques. The locking pin 14 is supported via the solenoid 13 to a housing 19 of the locking device 12 so that it can support the strong torques of the motor shaft 9 and thus the walls of the steering shaft 51. The solenoid 13 thus serves as an actuator for the locking pin 14. To the locking pin 14 after switching off the solenoid 13 back out of the locking groove 16 of the star latch 15th

herauszubewegen, a spring 20 is provided with their

movable end 21 is connected to the locking star 15 remote from the end 22 of the locking pin 14, while the fixed end 23 of the spring 20 is supported on the solenoid 13. As can be seen in Figures 5 to 8 and 1 1, is between the

Raststern 15 and the motor shaft 9 and the steering shaft 51, an elastic body 25 is arranged, the rotationally fixed connection between the

Raststern 15 and the motor shaft 9 and the steering shaft 51 changed to the effect that a certain relative rotation of the detent star 15 relative to the motor shaft 9 and the steering shaft 51 is made possible. In this way, a slight rotation of the steering shaft 51 (and thus the motor shaft 9) is possible even with a latched locking device 12, with increasing rotational angle Δ ψ an increasing

Counter torque M builds up, which has a progressive increase, as can be seen from Figure 9. The elastic body may be formed as an elastomeric ring 24. Also other elastic

Elements come into question, for example, a tolerance ring 25, as shown in Figures 3 and 4, or a torsion spring. The tolerance ring allows, when a certain limit torque is exceeded in the locked state on the steering shaft 51 that a Relative rotation between detent star 15 and the motor shaft 9 and the steering shaft 51 can take place, so that an overload protection is created, which protects the system from destruction. In Figures 7 and 8, the situation is shown in which the elastomeric ring 24 is increasingly deformed by increasing torque of the motor shaft 9 with locked locking device 12 in the direction of rotation.

The increasing torque M with increasing steering angle Δ ψ the

Steering shaft 51 gives the driver a feeling for the stop, either the Lenkradendanschlag or the stop of a vehicle wheel 46 on an obstacle, such as a curb, so that it does not exert an even higher torque on the steering wheel 42, which

could possibly lead to destruction or malfunction of the steering system.

Figure 10 shows another embodiment of the invention, in which the locking device 12 is mounted on a jacket tube 53 of the steering column and acts directly on the steering shaft 51. In Figure 1 1 can be seen the steering shaft 51 on which an elastomeric ring 24 is mounted rotatably. On the elastomer ring 24, in turn, a detent star 15 is attached, which is provided as well as in the other embodiments with locking grooves 16, in which the locking pin 14 engages when turning on the solenoid 13. Incidentally, all the functions of this embodiment correspond to those of the previously described embodiments, and all variants of the prescribed embodiments are applicable here as well. The invention thus provides a particularly simple and compact locking device 12 for the steering operation of a steer-by-wire steering system that reliably simulates steering stops in a realistic-looking manner. LIST OF REFERENCE NUMBERS

1 steer-by-wire steering device

2 steering wheel assembly

3 connection cable

4 steering housing

5

6 electric motor

7 rotary encoders

8 torque generating unit

9 motor shaft

10 gear shaft with worm wheel

1 1 gear

12 locking device

13 solenoid

14 stop bolts

15 Raststern

16 locking groove

17 End of the locking bolt

18 side walls

19 housing

20 spring

21 movable end of the spring

22 end of the locking bolt

23 fixed end of the spring

24 elastomer ring

25

26

27

28

29

Tolerance ring Steering motor Steering pinion

Rack tie rod vehicle grade

Steering shaft steering wheel casing pipe

Claims

1

Steer-by-wire steering device for motor vehicles, with a

Steering shaft (51) which is connected at one end with a steering wheel (52) and on which an electric motor (6) acts and

Generates steering torque that gives the driver feedback on the forces acting on the steered vehicle wheels (46) forces, and with one on the steering shaft (51) or the motor shaft (9) of

Electric motor (6) arranged locking device (12) for blocking the rotation of the steering shaft (51), characterized

in that the steering shaft (51) or the motor shaft (9) is connected to a detent star (15) which has detent grooves (16) arranged distributed over its circumference, and in that one of

Steering shaft (51) or the motor shaft (9) bearing housing (19) is mounted a locking device having a locking pin (14) by means of an actuator (13) from the outside into a locking groove (16) of the locking star (15) during steering operation is latched.

Steering device according to claim 1, characterized in that the detent star (15) and the detent pin (14) on the motor shaft (9) of the electric motor (6) are arranged.

Steering device according to claim 1 or 2, characterized in that the actuator of the detent device comprises a solenoid (13) in which a magnetic detent pin (14) in the direction of the

Raststern (15) towards longitudinally displaceable, so that it engages with its the star (15) facing the end (17) in a latching groove (16) of the latching star (15) when electrically energized solenoid (13).

4. Steering device according to claim 3, characterized in that the latching bolt (15) facing away from the rest star at its end 2

(22) is connected to a movable end (21) of a spring (20) whose fixed end (23) on the solenoid (13) is supported, so that the spring (20) the locking pin (14) at electrically

disconnected solenoid (13) from the locking groove (16) pulls out. 5. Steering device according to one of the preceding claims,

characterized in that the side walls (18) of the latching grooves (16) of the latching star (15) are aligned parallel to the axis of the latching bolt (14).

6. Steering device according to one of the preceding claims,

characterized in that operatively between the

Raststern (15) and the steering shaft (51) or motor shaft (9) an elastic body (24, 25) is arranged, with a latched locking pin (14) a small rotation {A φ) of the steering shaft (51) allows, with a increasing counter torque (M) builds up.

7. Steering device according to claim 6, characterized in that the elastic body is an elastomeric ring (24).

8. Steering device according to claim 6, characterized in that the elastic body is a torsion spring. 9. Steering device according to claim 6, characterized in that the elastic body is a tolerance ring (25).