DE102022202556A1 - Steering column for a motor vehicle - Google Patents

Abstract

The present invention relates to a steering column (2) for a motor vehicle, comprising a steering spindle (51) rotatably mounted in a casing unit (53) about a longitudinal axis (L), and comprising a feedback actuator (6) which has an electric motor (7 ) with a motor shaft (71) which can be driven to rotate about a motor axis (M), which is coupled to the steering spindle (51) via a gearbox (8) attached axially to the front of the motor (7), the motor (7) having a Control unit (9) is connected for electrical control, which is attached axially to the rear of the motor (7). In order to enable a more compact structure and a safer arrangement of the control unit, the invention proposes that the motor shaft (71) is arranged parallel to the longitudinal axis (L).

Description

State of the art

The invention relates to a steering column for a motor vehicle, comprising a steering spindle rotatably mounted in a jacket unit about a longitudinal axis, and comprising a feedback actuator which has an electric motor with a motor shaft which can be driven in rotation about a motor axis and which is mounted axially on the front of the motor attached gear is coupled to the steering spindle, the motor being connected to a control unit for electrical control, which is attached axially to the rear of the motor.

Steer-by-wire steering systems for motor vehicles receive manual steering commands from the driver like conventional mechanical steering systems by turning a steering wheel, which is attached to the driver's side, the rear end in the direction of travel, of a steering spindle that can be rotated about its longitudinal axis. However, in contrast to conventional steering systems, the steering spindle is not mechanically connected to the wheels to be steered via a steering gear, but rather interacts with rotation sensors that detect the steering command and send an electrical control signal generated from it to a motorized steering actuator, which is operated by means of a Electric actuator sets a corresponding steering angle of the wheels.

With steer-by-wire steering systems, the driver does not receive any direct mechanical feedback from the steered wheels via the steering train, which in conventional mechanically coupled steering systems is a reaction or restoring moment depending on the road surface, the vehicle speed, the current steering angle and other operating conditions are reported back to the steering wheel via the steering gear and the mechanical continuous steering shaft. The lack of haptic feedback makes it difficult to reliably grasp current driving situations and to carry out intuitively appropriate steering maneuvers, which impairs vehicle steerability and thus driving safety.

In order to create a realistic driving experience, it is known in the prior art to measure actual momentary parameters such as vehicle speed, steering angle, steering reaction torque and the like in a driving situation or to calculate them in a simulation, and to form a feedback signal from them, which in a feedback actuator is fed. The feedback actuator has an electric motor, the motor shaft of which is coupled to the steering spindle via a gearbox. When driving, the feedback signal is entered into a control unit, which electrically controls the motor in order to couple a restoring torque (feedback torque) corresponding to the real reaction torque into the steering wheel via the steering spindle. Such “force feedback” systems give the driver the haptic impression of a real driving situation, like with conventional steering, which makes it easier to react intuitively.

From the DE 2019 208 814 A1 A steer-by-wire steering system with a feedback actuator is known. In this case, the motor shaft is led axially out of the front of the motor with respect to the motor axis and is coupled to the transmission on the input side. On the output side, the transmission is coupled to the steering spindle, which can be rotated about the longitudinal axis and is arranged transversely to the motor shaft. The control unit is mounted on the rear of the engine, on the front side facing away from the transmission. Because the motor axis and the longitudinal axis run transversely to one another, the entire length of the motor projects relatively far across the longitudinal axis, with the control unit being arranged in the area that projects furthest outwards. The disadvantage of this is that a relatively large installation space is required and the control unit that projects outwards is at risk of mechanical damage.

In view of the problems explained above, it is an object of the present invention to enable a more compact structure and a safer arrangement of the control unit.

Presentation of the invention

This object is achieved according to the invention by the steering system with the features of claim 1. Advantageous developments result from the subclaims.

In a steering column for a motor vehicle, comprising a steering spindle rotatably mounted in a casing unit about a longitudinal axis, and comprising a feedback actuator which has an electric motor with a motor shaft which can be driven in rotation about a motor axis and which has a gearbox attached axially to the front of the motor is coupled to the steering spindle, wherein the motor is connected to a control unit for electrical control, which is attached axially to the rear of the motor, it is provided according to the invention that the motor shaft is arranged parallel to the longitudinal axis.

The motor shaft is on the front, by definition on the front axial face of the motor, with the input shaft of the gearbox mounted there bes rotatably connected, for example via a front shaft journal of the motor shaft. At the rear, on the rear axial end face of the motor, the control unit is mechanically fixed and electrically connected to control the motor.

According to the invention, the motor axis is arranged parallel to the longitudinal axis. An angular deviation of approximately +/- 10° for exactly parallel alignment can be included in order to compensate for any tolerances or to be able to make necessary adjustments. In any case, the motor's axial length is essentially aligned in the longitudinal direction, axially with respect to the longitudinal axis. The motor shaft is at a distance from the steering spindle transversely to the longitudinal axis, i.e. radially. This results in the main advantage that the motor and control unit can be arranged next to the casing unit to save space. This makes it possible to use a relatively powerful motor which - seen axially in the direction of the motor axis - is relatively long, but - measured transversely to the motor axis - has a relatively small motor cross section, in other words a motor with a relatively long axially, but slim design. The motor can extend adjacent to the casing unit, so that the overall cross section of the steering column, measured via the casing unit and the motor, can be kept relatively small, in which case sufficient motor power to generate the feedback torque can be provided .

In the prior art, a larger axial length of the motor in order to realize a higher drive power would lead to a design that extends widely across the longitudinal axis and is unfavorable in terms of optimized use of installation space. An increased engine cross section would also be disadvantageous. The invention, however, makes it possible to adapt the dimensions of the motor to the dimensions of the casing unit in such a way that a compact, space-saving steering column can be realized.

A further advantage of the invention is that the control unit arranged on the rear of the engine does not protrude freely and unprotected laterally, relatively far transverse to the longitudinal axis, as in the prior art, but is protected in an axial direction from the rear of the engine and laterally from the outside of the engine Shell unit can be accommodated in a limited niche. This means that the control unit is better protected against mechanical damage from the outside. Additional protective measures that may be required in the prior art, such as a particularly robust housing or the like, can be omitted in the design according to the invention, and effective protection can be achieved with less effort.

It can advantageously be provided that the gear is arranged on the front side of the casing unit. The transmission is positioned in front of a front axial end side of the casing unit in such a way that an output-side transmission axis is aligned with the longitudinal axis, and the steering spindle can be coupled directly to a transmission shaft or a transmission wheel at the transmission output. The gearbox is thus arranged axially in front of the front end faces of the motor and the casing unit. This makes it possible for the transmission to be arranged essentially within the overall cross section of the steering column, which is essentially determined by the sum of the cross sections of the jacket unit and the feedback actuator attached to it. According to the invention, the total cross-sectional area can be formed completely or at least predominantly by the motor cross section and the jacket cross section, this is the cross section of the jacket unit. The gear wheels of the transmission, for example belt wheels, gear wheels or the like, can be connected to the motor shaft and the steering spindle on the input and output sides, and including other transmission means such as intermediate wheels, belts or the like, can be accommodated within the said overall cross-sectional area. It is possible that the transmission does not protrude outwards, or at least not significantly, transversely to the longitudinal axis. This makes it possible to achieve a particularly compact, space-saving, easy-to-install and robust design of the steering column.

It is preferably possible for the control unit to be arranged next to the casing unit with respect to the longitudinal axis. The motor and the control unit extend with respect to a longitudinal section within the length of the jacket unit. Because the control unit is arranged in the rear area of the feedback actuator next to the casing unit, an optimized design and good accessibility can be achieved.

It can preferably be provided that the feedback actuator has a motor housing, a control housing and a gear housing. The rotor of the motor with the rotor shaft is arranged in the motor housing, the control unit in the control housing, and the transmission in the transmission housing. These housings can be designed individually and joined together by means of connecting elements to form an actuator housing, or can be at least partially integrated into a one-piece or one-piece actuator housing. The actuator housing can preferably be attached to the outside of the casing unit, with one or more of the aforementioned housings being connected to the casing unit can be connected. For example, the gearbox housing can be attached to the front of the motor housing and/or to the casing unit, preferably in each case at the front, whereby the entire actuator housing is fixed to the casing unit. It is alternatively or additionally possible for a one-piece actuator housing to be fixed to the casing unit with a different area.

An advantageous embodiment is that the control unit has an area-wide circuit board. A circuit board, also referred to as a printed circuit board, serves as a mechanical support for the electronic components of the control circuit, and has a flat base body made of an insulating carrier material, for example a glass fiber reinforced plastic (GRP), which has conductor tracks for electrically connecting the components. The circuit board is electrically connected to the motor and can preferably be arranged transversely to the motor axis, preferably in the control housing. This allows a robust, production-friendly structure to be realized.

It can be provided that the circuit board has a plurality of circuit board sections arranged in a stacked or angled manner. The electrical components are arranged distributed over at least two circuit board sections, which are electrically and mechanically connected. These board sections are each smaller than a one-piece, continuous board and can be stacked one above the other, preferably axially in the direction of the motor axis, and/or arranged at an angle relative to one another. As a result, the available installation space, for example in a control housing, can be used in an optimized manner.

An advantageous development can provide that the circuit board is designed to be flexible, at least in sections. At least two circuit board sections or partial circuit boards are mechanically and electrically connected to one another via a flexible, bendable connecting section. To form an angled or stacked arrangement, the board can simply be bent or folded, simplifying assembly.

It may be advantageous for the control unit to be housed within a cross-sectional area of the engine. The control unit is arranged completely within the motor cross-section when viewed in the direction of the motor axis, so it does not protrude outwards across the cross-sectional area of the motor transversely to the motor axis. This allows an advantageous, slim design to be realized, particularly when using a relatively long motor with a small motor cross section.

The aforementioned embodiment can be implemented in that the control unit is arranged in a control housing which is designed flush with the motor housing. The control housing can be attached to the motor housing or integrated into the motor housing.

Alternatively, it is possible for the control unit to be arranged in a control housing that projects beyond the motor housing transversely to the motor axis. As a result, a one-piece circuit board can be used, which has larger dimensions in terms of area and can be designed to be rigid so that it can have all of the electrical components of the control circuit. It can be advantageous that the control housing can be flatter in the direction of the motor axis, and a cost-effective circuit board that is easy to manufacture and assemble can be used.

It can advantageously be provided that the feedback actuator has an electrical connection element arranged on the rear and connected to the control unit. The connection element is used to connect the control unit to the motor vehicle electrical system. It can preferably include one or more plug connections, which can preferably be arranged on the rear, rear end face, preferably on the control housing. Plug connectors can be provided which comprise contact elements, holding elements and the like that can be electrically and mechanically, preferably releasably, connected to one another in a manner known per se. In this way, it is possible to lead the electrical connection axially out of the feedback actuator parallel to the jacket unit, which can ensure a compact structure and simple assembly.

It is possible for the transmission to be designed as a belt transmission or gear transmission. The transmission can accordingly have belt wheels or gears in mesh with the transmission, which are connected to the motor shaft and the steering spindle.

It can be advantageous for the control unit to have at least one sensor element that interacts with the steering spindle and/or the motor shaft. The sensor element can, for example, comprise an electronic rotation sensor for detecting a rotation or angular position of the steering spindle and/or the motor shaft. This makes it possible to measure the rotational movements generated by the feedback actuator, and the generated feedback torque can be electronically controlled. In addition, by comparing the rotations of the steering spindle and motor shaft, the function can be monitored, for example whether slip occurs in the transmission, or the torque transmission is disturbed in some other way. This can increase functional and operational reliability. The arrangement according to the invention enables a functionally reliable and easy-to-install positioning of the sensor element(s) in the front area of the steering spindle and/or motor shaft.

It can be advantageous for the steering column according to the invention to be designed as a steer-by-wire steering column. This is an electric steering input device in which the manual steering handle is not mechanically connected to the wheels to be steered, but rather interacts with rotation angle or torque sensors that detect the manually entered steering command and generate an electrical control signal from it and send it to a steering actuator , which uses an electric actuator to set a steering angle of the wheels that corresponds to the steering command. Such steering systems can preferably be used in autonomously operated vehicles.

Description of the drawings

• 1 eine schematische Darstellung eines Steer-by-Wire-Lenksystems,
• 2 einen erfindungsgemäßen Feedback-Aktuator in einer schematischen perspektivischen Darstellung,
• 3 einen Feedback-Aktuator gemäß 2 in einer weiteren schematischen perspektivischen Darstellung,
• 4 den Feedback-Aktuator gemäß 2 in einer schematischen, teilweise geöffneten Darstellung,
• 5 die Steuereinheit des Feedback-Aktuators gemäß 4 in einer schematischen Darstellung,
• 6 eine zweite Ausführung eines erfindungsgemäßen Feedback-Aktuators in einer schematischen perspektivischen Darstellung.

Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. Show in detail:

• 1 a schematic representation of a steer-by-wire steering system,
• 2 a feedback actuator according to the invention in a schematic perspective representation,
• 3 according to a feedback actuator 2 in another schematic perspective representation,
• 4 the feedback actuator accordingly 2 in a schematic, partially opened representation,
• 5 the control unit of the feedback actuator according to 4 in a schematic representation,
• 6 a second embodiment of a feedback actuator according to the invention in a schematic perspective representation.

Embodiments of the invention

In the various figures, the same parts are always provided with the same reference numbers and are therefore usually only named or mentioned once.

The direction information refers to the regular direction of travel of a vehicle that is not shown in detail, with the direction forward in the figures being indicated as direction V with an arrow, and correspondingly the opposite direction H to the rear.

1 shows schematically a steer-by-wire steering system 1, which includes a steering column 2 as an input unit, which is connected to an electric steering drive 4 via an electrical line 3.

The steering drive 4 includes a servomotor 41 connected to the electrical line 3, which initiates a steering actuating torque into a steering gear 42. There, the steering control torque is converted into a translational movement of tie rods 45 via a pinion 43 and a rack 44, whereby a steering angle of the steered wheels 46 is brought about in a manner known per se by pivoting steering knuckles. Alternatively, the steered wheels 46 can be connected to individually controllable electric actuators to implement individual wheel steering.

The input unit 2 has a steering shaft 51, at the rear end of which a steering wheel 52 is attached, and which is rotatably mounted in a jacket unit 53 about a longitudinal axis L directed from the back to the front.

The steering column 2 has a feedback actuator 6, which is on the casing unit 53 in the 2 , 3 , 4 and 6 is shown in different views. This shows 2 a cropped overall view of the feedback actuator 6, which is attached to the casing unit 53 - indicated by dashed lines. 3 shows another perspective view, and 4 a partially exploded representation.

The feedback actuator 6 has an electric motor 7 which has a motor housing 61 in which a motor shaft 71 is mounted so that it can rotate about a motor axis M. The motor shaft 71, which is covered by the motor housing 61 in this illustration and is indicated by dashed lines, is arranged parallel to the longitudinal axis L.

The motor axis M and the longitudinal axis L run parallel and are at a distance A from each other.

On the front side, on its front axial end face, a gear 8 is attached to the motor 7. This has a gear housing 63, in which gear means (not shown here in detail) for generating a torque transmission from the motor shaft 71 to the steering spindle 51 are arranged, for example toothed belt wheels with a rotating toothed belt, gears or the like.

The gearbox 63 is fixed to the motor housing 61, for example flanged on the front side by means of fastening bolts. To connect to the steering column 1, the gear housing 63 is also fastened to the front of the casing unit 53, in the example shown as flanged to the motor housing 61.

A control housing 62, in which an electrical control unit 9 is arranged, is attached to the rear of the motor housing 61, on the rear axial end face of the motor 7.

The motor housing 61 is essentially cylindrical in shape and extends axially in the direction of the motor axis M. In the 2 until 5 In the first exemplary embodiment shown, the control housing 62 is also essentially cylindrical in shape, for example in the form of a tubular sleeve or hood, as in the exploded view of 4 is recognizable. The diameters of the two housings 61 and 62 are approximately the same, so that they occupy approximately the same cross section in the direction of the motor axis M, namely the motor cross section.

The control housing 63 is preferably tightly closed by cover elements 64 which are attached to the outer end face opposite the motor housing 61. One or more plug housings 65 can be formed on a cover element 64, which has an electrical connection element in order to be able to accommodate a corresponding plug, not shown here, for connecting a control line connected to the vehicle electrical system.

The aforementioned housings 61, 62 and 63 together form an actuator housing which is mounted on the casing unit 53 on the steering column 1.

5 shows the control unit 9 schematically in an axially exploded view in the direction of the motor axis M.

The circuit board 91 is formed from two rigid circuit board sections 92, which are arranged stacked in the direction of the motor axis M, and which are electrically connected to one another via a flexible connecting section 93, which is formed, for example, by a flexible, bendable circuit board.

Connecting elements 94 can be arranged between the board sections 92, for example for fixation, as spacers or the like.

The contact element facing the motor housing 61 can be used via contact elements 95 5 The circuit board section 92 shown on the left can be electrically connected to the motor 7.

The axially outer one facing away from the motor housing 61 5 The circuit board section 92 shown on the right can have contact elements 96, which are preferably positioned in the plug housing(s) 65 and, for example, include contact pins of a detachable electrical connection element, for example a plug connector.

The board sections 92 are dimensioned so that the board 91 can be angled or folded to save space and inserted into the control housing 63.

6 shows an alternative embodiment in which the circuit board 91 is designed to be rigid in one piece and is larger in area than the motor cross section. The control housing 62 projects transversely to the motor axis M over the motor housing 61. However, it is axially flatter, measured in the direction of the motor axis M, than in the first embodiment described above.

In all of the embodiments shown, the plug housings 65 are open at the front to the rear, so that a corresponding electrical plug connector can be plugged in in an axial direction from the back to the front in an easy-to-assemble manner.

Reference symbol list

1

Steering system

2

Steering column (input unit)

3

Line

4

Steering drive

41

Servomotor

42

Steering gear

43

pinion

44

Rack

45

tie rod

46

wheel

5

Feedback actuator

51

Steering spindle

52

steering wheel

53

Shell unit

6

Feedback actuator

61

Motor housing

62

Control housing

63

Gearbox housing

64

Lid element

65

Connector housing

7

engine

71

Motor shaft

8th

transmission

9

Control unit

91

circuit board

92

Board section

93

connection section

94

connecting element

95, 96

Contact element

L

Longitudinal axis

M

Motor axis

A

Distance

v

Direction forward

H

Direction backwards

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The 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 2019208814 A1 [0005]

Claims (14)

Steering column (2) for a motor vehicle, comprising a steering spindle (51) rotatably mounted in a jacket unit (53) about a longitudinal axis (L), and comprising a feedback actuator (6) which has an electric motor (7) with a Motor axis (M) has a rotatably drivable motor shaft (71), which is coupled to the steering spindle (51) via a gearbox (8) attached axially to the front of the motor (7), the motor (7) being connected to a control unit (9). electrical control is connected, which is attached axially to the rear of the motor (7), characterized in that the motor shaft (71) is arranged parallel to the longitudinal axis (L). Steering column after Claim 1 , characterized in that the gear (8) is arranged on the front side of the jacket unit (53). Steering column according to one of the preceding claims, characterized in that the control unit (9) is arranged next to the casing unit (53) with respect to the longitudinal axis (L). Steering column according to one of the preceding claims, characterized in that the feedback actuator (6) has a motor housing (61), a control housing (62) and a gear housing (63). Steering column according to one of the preceding claims, characterized in that the control unit (9) has a surface-extended circuit board (91). Steering column after Claim 5 , characterized in that the board (91) has a plurality of board sections (92) arranged in a stacked or angled manner. Steering column according to one of the previous ones Claims 5 or 6 , characterized in that the circuit board (93) is designed to be flexible at least in sections. Steering column according to one of the preceding claims, characterized in that the control unit (9) is housed within a cross-sectional area of the motor (7). Steering column according to one of the preceding claims, characterized in that the control unit (9) is arranged in a control housing (62) which is designed flush with the motor housing (61). Steering column according to one of the preceding claims, characterized in that the control unit (9) is arranged in a control housing (62) which projects beyond the motor housing (61) transversely to the motor axis (M). Steering column according to one of the preceding claims, characterized in that the feedback actuator (6) has an electrical connection element (65) arranged on the rear and connected to the control unit (9). Steering column according to one of the preceding claims, characterized in that the transmission (7) is designed as a belt transmission or gear transmission. Steering column according to one of the preceding claims, characterized in that the control unit (9) has at least one sensor element which interacts with the steering spindle (51) and/or the motor shaft (71). Steering column according to one of the preceding claims, characterized in that it is designed as a steer-by-wire steering column.

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