DE102024104087A1 - Force feedback actuator of a steering column - Google Patents

Abstract

Force feedback actuator of a steering column of a vehicle with an electromagnetic braking device (1), wherein the magnetorheological braking device (1) has a shaft arranged along a rotational axis, a stator (4, 16, 20) and a rotor (3, 17, 19) and with at least one housing element arranged around the shaft, wherein the stator (4, 16, 20) has a coil carrier (6) with at least one coil (5), characterized in that the coil carrier (6) has a friction surface (7) and wherein at least one magnetizable, annular elastic spring plate (10, 21) is arranged between the friction surface (7) and the rotor (3, 17, 19).

Description

Field of the invention

The present invention relates to a force feedback actuator of a steering column of a vehicle and a steer-by-wire steering system with such a force feedback actuator.

Background of the invention

In today's steering systems and steering devices, the steering wheel can be adjusted in height and length, i.e., in an axial position. In such adjustment systems, the steering column elements or steering shaft elements are movable relative to each other, for example, designed as a telescopic arrangement. This allows the steering wheel to be adjusted to a position that suits the driver.

Steer-by-wire steering systems are also known, which dispense with the mechanical connection between the steering wheel and the axle to be steered via the steering column, and the steering of the wheels is controlled via corresponding signals. Steer-by-wire steering systems can be divided into two types: steer-by-wire steering systems with a force feedback actuator located away from the steering wheel and steer-by-wire steering systems with a force feedback actuator located close to the steering wheel.

Steer-by-wire steering systems with a force-feedback actuator located away from the steering wheel utilize common crash elements, such as sheet metal strips that plastically deform when a defined force is exceeded. Plastic sleeves on the telescopic steering shaft are also known, which are destroyed by a predetermined force. Steer-by-wire steering systems with a force-feedback actuator located close to the steering wheel can eliminate the need for a telescopic steering shaft.

Furthermore, such force-feedback actuators are known to incorporate electric motors, spring devices, and braking devices, which enable targeted feedback and deceleration, even to the point of locking the steering wheel, for example, at virtual stops. Magnetorheological braking devices, among others, can be used for this purpose.

The DE 10 2011 013 957 A1 shows a brake of a steering lock in an EPSc system and discloses a spring element which is actuated by a magnetic force.

The US2002/ 0108804 A2 discloses a powder brake in which the rotor and the stator are formed with an excitation coil whose magnetic flux leads to powder-filled gaps, whereby the iron powder contained therein forms adhering, braking “threads” or “chains”.

Summary of the invention

It is therefore an object of the present invention to provide a force feedback actuator with an improved powderless, sealless electromagnetic braking device.

According to the invention, this object is achieved by a force feedback actuator of a steering column of a vehicle with an electromagnetic braking device, wherein the magnetorheological braking device has a shaft arranged along a rotational axis, a stator and a rotor and with at least one housing element arranged around the shaft, wherein the stator has a coil carrier with at least one coil, wherein the coil carrier has a friction surface and wherein at least one magnetizable, annular elastic spring plate is arranged between the friction surface and the rotor.

This design, using the spring plate, makes it possible to create a better tactile friction behavior and increased friction force. This occurs because the spring plate is pulled directly onto the coil carrier when the coils are energized, creating numerous small friction contacts that, on average, produce a uniform friction force. This effect can be enhanced, for example, by applying an additional friction layer to the spring plate, such as friction varnish, friction paper, sliding layer, Teflon, and/or by additionally greasing it.

Preferably, two or more coils are provided. Each coil is wound externally and can also be axially inserted into a thin plastic or steel sheath. The coils can be inserted into the stator center section from either side. The rotor is a strip carrier and can be made of aluminum, metal, or plastic. The rotor or strip carrier is preferably made of a non-magnetizable material so that the magnetizable spring sheet is drawn toward the stator in the magnetic field, not toward the rotor.

According to one embodiment of the invention, the stator is arranged around the outer circumference of the rotor. This entire unit forms an internal rotor. This design is particularly advantageous when a steering shaft is present and the rotor is arranged directly around it.

According to one embodiment of the invention, the rotor is arranged around the outer circumference of the stator. This entire unit forms an external rotor. With this arrangement, the coils can be wound particularly easily into corresponding recesses in the stator and, if necessary, encapsulated. The advantage of such an arrangement is that a friction radius is located very far outwards, thereby enabling a high frictional torque. In particular, the use of multiple coils in separate, machined coil grooves with additional pole and friction surfaces in between is particularly easy to implement with this design and also increases the frictional torque.

Preferably, a gap is provided between the friction surface and the rotor, in which the spring plate is arranged, with a width of less than 1 mm. Furthermore, the gap also serves to protect the spring plate against deformation, such as buckling.

According to one embodiment of the invention, the circular elastic spring plate has at least one slot. This serves to achieve a resilient effect of the spring plate, since the spring plate exerts a larger or smaller circumferential angle during radial movement and thus "breathes" in the slot. Advantageously, the thickness of the spring plate can be 0.2-0.5 mm, and the width 5-50 mm, so that the cross-sectional area can transmit a sufficient amount of longitudinal force (i.e., braking force).

The spring plate can be preloaded so that it rests against the rotor, thus maintaining an air gap (typically 0.5 mm) between the friction surfaces. However, the spring plate is advantageously shaped so that it contacts the friction surfaces with low force in localized areas. This creates a well-adjustable brake control behavior because, when energized, the spring plate does not first move through the gap and then snap onto the friction surface, but rather simply increases its contact force with the friction surface without movement.

Due to its magnetizability, the spring plate acts like an exceptionally thin armature, closing the stator's open magnetic circuit. Although the spring plate is thin, it has a significantly higher permeability than the powder in magneto-rheological brakes, so it is strongly attracted and a high braking torque can be achieved.

According to one embodiment of the invention, the annular elastic spring plate has at least one guide contour. The guide contour can be provided axially and can be formed, for example, by lateral grooves, partially or fully circumferentially, possibly even by several small tabs, by a slight crown, or by longitudinal grooves. Furthermore, a friction zone of the spring plate and/or the coil carrier can have a surface modification, which can be formed, for example, by glued paper/friction paper, especially with fibers, greasing (also in combination with paper), coating (galvanic, Teflon spray, anti-friction varnish, etc.), or corrosion protection.

Preferably, a connecting element is provided which is arranged in such a way that it connects the spring plate to a rotating component and/or rotor. This serves to clamp the spring plate to the rotor. The connecting element can be screwed or connected to the external component and/or rotor in some other way. Uniform clamping (over a large area) has the advantage over other fastening techniques that the very thin spring plate is not exposed to locally high, damaging force transmission.

According to an alternative embodiment of the invention, the annular elastic spring plate has at least one wing element, wherein the at least one wing element contacts the stator at the friction surfaces and optionally surrounds it.

Further aspects of the invention relate to an adjustment unit and a steer-by-wire steering system using a force feedback actuator according to the invention.

Short description of the drawing

• 1 einen Längsschnitt einer elektromagnetischen Bremsvorrichtung eines nicht näher dargestellten erfindungsgemäßen Forcefeedback-Aktuators gemäß einer ersten Ausführungsform,
• 2 einen Detailansicht der elektromagnetischen Bremsvorrichtung aus 1,
• 3 eine Darstellung eines Rotors der elektromagnetischen Bremsvorrichtung aus 1,
• 4 eine Darstellung eines Federblechs elektromagnetischen Bremsvorrichtung aus 1,
• 5 eine Darstellung der Spulen unbestromt elektromagnetischen Bremsvorrichtung aus 1,
• 6 eine Darstellung der Spulen bestromt elektromagnetischen Bremsvorrichtung aus 1,
• 7 eine Darstellung der Spule mit Federblech,
• 8 einen Längsschnitt einer elektromagnetischen Bremsvorrichtung eines nicht näher dargestellten erfindungsgemäßen Forcefeedback-Aktuators gemäß einer zweiten Ausführungsform,
• 9 einen Längsschnitt einer elektromagnetischen Bremsvorrichtung eines nicht näher dargestellten erfindungsgemäßen Forcefeedback-Aktuators gemäß einer dritten Ausführungsform, und
• 10 einen Längsschnitt einer elektromagnetischen Bremsvorrichtung eines nicht näher dargestellten erfindungsgemäßen Forcefeedback-Aktuators gemäß einer vierten Ausführungsform.

Four exemplary embodiments of the invention are illustrated below with reference to ten figures. They show:

• 1 a longitudinal section of an electromagnetic braking device of a force feedback actuator according to the invention (not shown in detail) according to a first embodiment,
• 2 a detailed view of the electromagnetic braking device 1 ,
• 3 a representation of a rotor of the electromagnetic braking device from 1 ,
• 4 a representation of a spring plate electromagnetic braking device from 1 ,
• 5 a representation of the coils de-energized electromagnetic braking device from 1 ,
• 6 a representation of the coils energized electromagnetic braking device from 1 ,
• 7 a representation of the coil with spring plate,
• 8 a longitudinal section of an electromagnetic braking device of a force feedback actuator according to the invention (not shown in detail) according to a second embodiment,
• 9 a longitudinal section of an electromagnetic braking device of a force feedback actuator according to the invention (not shown in detail) according to a third embodiment, and
• 10 a longitudinal section of an electromagnetic braking device of a force feedback actuator according to the invention (not shown in detail) according to a fourth embodiment.

Detailed description of the drawings

1 to 4 show various representations of a force feedback actuator according to the invention (not shown in detail) with an electromagnetic braking device 1 according to a first embodiment.

The electromagnetic braking device 1 has a shaft 2 arranged along a rotational axis, which is formed integrally with a rotor 3. Furthermore, a stator 4 is formed around the outer circumference of the rotor 3. The stator 4 itself is designed such that it forms a three-part coil carrier 6, in which, in this embodiment, two coils 5 are arranged. The coils 5 are wound from the outside, optionally in a thin plastic or steel sheath, and are inserted axially into the coil carrier 6.

The coil carrier 6 has at least two (N-pole and S-pole of the electromagnet), in the example shown, three friction surfaces 7, which are arranged opposite the outer circumference of the rotor 3. A gap 9 is formed between the friction surface 7 and the rotor 3, which extends over the circumference. At least one circular ring-shaped elastic spring plate 10 is arranged in this gap 9. Circular means that the spring plate extends around the outer or inner circumference of the rotor/stator. The gap 9 has a width of 1 mm, and the spring plate is 0.2 mm thick.

Furthermore, a connecting element 11 is provided, which is screwed against the rotor 3 in order to clamp the spring plate 10 between them. (see 3 )

4 shows the spring plate 10, which has a slot 12 and a fastening zone 13 for the connecting element 11. The fastening zone 13 is designed here by means of two holes for a screw connection.

The 5 and 6 each show a representation of the coils in a de-energized and energized state.

In 5 the coils 5 are de-energized, ie the spring plate 10 is in contact with the rotor 3 and both elements can rotate. 6 shows the coils in a current-energized state. Here, the spring plate 10 is pulled onto the coil carrier 6 (except for the clamped area of the spring plate 10 with the connecting element 11). This creates friction between the rotor 3 and the spring plate 10 when it rotates.

7 shows a representation of the coil 5 with various designs of the spring plate 10. The spring plate 10 has at least one guide contour 14, which is provided axially and is formed, for example, by means of lateral grooves, partially or fully circumferentially, by means of a slight crowning or by longitudinal grooves.

The 8 to 10 show further embodiments of the invention. To simplify the description, identical components are designated by the same reference numerals. The following description therefore focuses on the differences.

8 shows a second embodiment. As can be seen, the rotor 17 is formed along a side surface 15 of the stator 16, which is formed in the axial direction, and around its outer circumference. In this embodiment, the stator 16 itself also has a coil carrier in which two coils 5 are arranged. The spring plate 10 is clamped to the rotor 17 by the connecting element 11.

9 shows another embodiment. Here, the spring plate 10 is clamped to a rotating outer part 18 by means of the connecting element 11. The coil carrier 6 with a coil 5 is arranged on the inside, as in the previous example. This is an external rotor.

10 shows a further embodiment. Here, a rotor 19, for example made of iron, is formed around the stator 20. The stator 20 has the coil 5. Between the rotor 19 and the stator 20, a spring plate 21 is arranged, which has a bent blade 22 in the direction of the stator 20. The spring plate 21 is connected to the rotor 19 by forming connected (in section it looks as if the spring plate is split - but in section it only has a hole through which a deformed pin of the rotor 19 protrudes)

List of reference symbols

1

Electromagnetic braking device

2

Wave

3

rotor

4

stator

5

Wash

6

Coil carrier

7

Outer circumference

8

Friction surface

9

gap

10

spring plate

11

connecting element

12

slot

13

fortification zone

14

Guide contour

15

side surface

16

stator

17

rotor

18

outer part

19

rotor

20

stator

21

spring plate

22

wing

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10 2011 013 957 A1 [0006]
• US 2002/ 0108804 A2 [0007]

Claims (10)

Force feedback actuator of a steering column of a vehicle with an electromagnetic braking device (1), wherein the magnetorheological braking device (1) has a shaft arranged along a rotational axis, a stator (4, 16, 20) and a rotor (3, 17, 19) and with at least one housing element arranged around the shaft, wherein the stator (4, 16, 20) has a coil carrier (6) with at least one coil (5), characterized in that the coil carrier (6) has a friction surface (7) and wherein at least one magnetizable, annular elastic spring plate (10, 21) is arranged between the friction surface (7) and the rotor (3, 17, 19). Force feedback actuator according to Claim 1 , wherein the stator (4, 16, 20) is arranged around the outer circumference of the rotor (3,17,19). Force feedback actuator according to Claim 1 , wherein the rotor (3,17,19) is arranged around the outer circumference of the stator (4, 16, 20) Force feedback actuator according to one of the preceding claims, wherein a gap (9) is provided between the friction surface (7) and the rotor (3, 17, 19), in which gap the spring plate (10) is arranged and wherein the gap (9) has a width of less than 1 mm. Force feedback actuator according to one of the preceding claims, wherein the annular elastic spring plate (10) has at least one slot. Force feedback actuator according to one of the preceding claims, wherein the annular elastic spring plate (10) has at least one guide contour. Force feedback actuator according to Claim 3 until 6 , wherein a connecting element (11) is provided which is arranged such that it connects the spring plate (10, 21) to a rotating component and/or rotor (3, 17, 19). Force feedback actuator according to one of the preceding claims, wherein the annular elastic spring plate (21) has at least one wing element (22) and wherein the at least one wing element (22) comprises the stator (20). Adjustment unit of a steering column of a vehicle comprising a force feedback actuator according to one of the preceding claims. Steer-by-wire steering system comprising a force feedback actuator or an adjustment unit according to one of the preceding claims.