WO2020043233A1

WO2020043233A1 - Feedback actuator for a steering device having a steering resistance system

Info

Publication number: WO2020043233A1
Application number: PCT/DE2019/100753
Authority: WO
Inventors: Manfred Kraus; Jochen Rosenfeld; Andreas Wöllner; Markus BAEUML; Georgi ANDREEV
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2018-08-30
Filing date: 2019-08-21
Publication date: 2020-03-05
Also published as: DE102018131185A1; DE102018131185B4

Abstract

The invention relates to a feedback actuator (10) for a steering device having a defined steering torque (L), having an outer housing assembly (12), comprising: a steering shaft (14) for coupling to a steering wheel (16), the steering shaft (14) being mounted rotatably about the longitudinal axis (L) thereof in the housing assembly (12); a bearing (18) for mounting the steering shaft (14); a frictional element (20) which is situated along the longitudinal axis (L) to generate a basic friction of the feedback actuator (10); a blocking device (22) for functions which require an active actuating torque greater than a defined steering torque (L) of a motor (26); an angle sensor system (24) for determining the rotor position for controlling a motor (26); and at least one first motor (26) for actively actuating a motor steering torque (M1) when a vehicle is in a switched-on operating state. The feedback actuator (10) has a steering resistance system (28) for providing the defined steering torque at the steering wheel (16), and the motor steering torque of the at least one motor (26) is smaller than the defined steering torque to be perceived by a motor vehicle driver. A feedback actuator (10) thus constructed according to the invention, is compact, and provides a realistically reproduced steering feel for motor vehicle drivers, the components being designed to have as little play as possible relative to one another.

Description

Feedback actuator for a steering device with a steering resistance system

The invention relates to a feedback actuator for a steering device

Direct drive. Such feedback actuators are used in particular in steer-by-wire steering systems for motor vehicles.

Steer-by-wire steering systems for motor vehicles take manual steering commands from the driver, like conventional mechanical steering systems, by turning one

Steering wheel counter to an input unit. This causes the rotation of a steering shaft, which, however, is not mechanically connected to the wheels to be steered via the steering gear, but rather interacts with angle of rotation or torque sensors, which detect the steering command introduced and emit an electrical control signal determined therefrom to a steering actuator by means of of an electric actuator sets a corresponding steering angle of the wheels.

With steer-by-wire systems, the driver does not receive any direct physical feedback from the steered wheels via the steering link, which is the case with

conventional mechanically coupled steering systems as reaction or

Return torque depending on the condition of the road, the

Vehicle speed, the current steering angle and other operating conditions are reported back to the steering wheel. The lack of haptic feedback makes it difficult for the driver to reliably record current driving situations and to carry out appropriate steering maneuvers, which increases vehicle steerability and thus

Driving safety will be impaired.

In order to produce a realistic driving experience, it is known in the prior art to use parameters such as from an actual current driving situation

Vehicle speed, steering angle, steering reaction torque and the like to detect or calculate in a simulation, and from this one

Form feedback signal, which is fed into a feedback actuator becomes. The feedback actuator is integrated in the input unit and has one

Actuator unit, which comprises an actuator serving as a manual torque or steering wheel actuator, and which, depending on the feedback signal, couples a return torque (feedback torque) corresponding to the real reaction torque via the steering shaft into the steering wheel. Such “force feedback” systems give the driver the impression of a real driving situation as with conventional steering, which facilitates an intuitive reaction.

A steer-by-wire steering system is known from DE 10 2008 036 730 A1, with an input unit which has an actuator unit driven by an electric motor. The electric motor can be controlled by an electronic control unit that adjusts the motor current as a function of measured values that characterize the respective driving situation. The motor shaft is directly coupled to the steering shaft, so the motor torque is identical to the manual torque that is coupled into the steering shaft. The electric motor is flanged axially to the jacket unit with respect to the longitudinal axis and the motor shaft is connected to the steering shaft mounted in the jacket unit via a coupling. An actuator unit of the same construction is shown in EP 2 414 211 B1. In the embodiment described therein, the steering shaft itself forms the motor shaft of the electric motor, so that a more compact structure can be achieved.

To apply a defined restoring torque in the steering wheel, the motor torque must be specified precisely in the known designs described above because of the direct coupling of the motor shaft to the steering shaft, which is a complex, fast and precise control of the

Motor current required in the control unit. In addition, relatively high control currents have to be provided in order to realize larger restoring torques. These requirements require a high level of control, so that

Control unit must be designed accordingly expensive. In addition, suitable electric motors with sufficiently high motor torques have relatively large dimensions for the application of realistic restoring torques, which is contrary to a compact construction. The task of the current development is to develop a feedback actuator for a compact steering device with a realistic simulation of the steering feel, which is designed to be as free of play as possible.

The object is achieved according to the invention by a feedback actuator having the features of claim 1. Preferred embodiments of the invention are specified in the subclaims and the following description, which can each represent an aspect of the invention, individually or in combination.

The invention thus relates to a feedback actuator for a steering device with a defined steering torque, with an outer housing arrangement, comprising a steering spindle for coupling to a steering wheel, the steering spindle being mounted in the housing arrangement so as to be rotatable about its longitudinal axis, a bearing for mounting the steering spindle, a friction element arranged along the longitudinal axis for

Generation of a basic friction of the feedback actuator, a blocking device for functions that require an active actuating torque greater than a defined steering torque of an engine, an angle sensor system for determining the rotor position for the

Regulation of a motor and at least one first motor for actively setting an engine steering torque in a switched-on operating state of a vehicle, characterized in that the feedback actuator has a steering resistance system for providing the defined steering torque on the steering wheel, the

Motor steering torque of the at least one motor is smaller than the defined one

Steering torque for perception by a motor vehicle driver. Because of the

Compensation by the steering resistance system in order to adjust the engine steering torque to the amount of the defined steering torque, the at least one engine can be made more compact compared to an engine without this steering resistance system. This advantageously reduces the installation space required and can also reduce the energy requirement for the system.

Has proven to be a particularly advantageous solution for a compact design

emphasized that the steering resistance system is a transmission. In particular, the transmission can have a transmission ratio of 50: 1 up to and including 70: 1, preferably essentially 60: 1. Such a transmission ratio has proven to be advantageous, on the one hand, to enable a compact construction and, on the other hand, to allow a construction that is as gentle as possible on the components.

It can be provided according to an advantageous embodiment of the invention that the steering resistance system has a gear designed as a cycloid gear. An eccentric of a drive unit drives a cam disk, which rolls inside a fixed pin ring and carries pins of an output unit. This allows for a construction that is as compact as possible, whereby the transmission also has a low noise and wear effect with an even load distribution. This enables a long service life.

As an alternative to the cycloidal gear it can be provided that the

Steering resistance system has a transmission designed as a Cyclobelt transmission. This has the advantage of a particularly low-play design.

The Cyclobelt transmission can preferably have a transmission input which is indirectly or directly connected to the motor shaft and is designed as a sun gear and which is surrounded by at least three planet gears which are encompassed by a single belt, the belt being connected to the steering spindle and in particular as a ring gear trained transmission output is surrounded, the transmission input and the transmission output coaxial to each other

are arranged. This arrangement of the components enables a uniform force distribution to take place, so that the component life is increased.

Furthermore, the transmission input can preferably have an at least partially elastic casing on the outside for acoustic decoupling.

In order to transmit the torque as evenly as possible and also with low noise, the belt can have an internal and / or external toothing. According to this exemplary embodiment, the feedback actuator is operated in a forced manner between the planet gears and the transmission output, which is designed in particular as a ring gear. This enables the feedback actuator to be designed with little play.

Another preferred embodiment of the feedback actuator can be designed such that the steering resistance system has at least two motors, preferably three motors, which are connected to the steering spindle via a respective belt drive. This further reduces the installation space required for each motor. In addition, this gives the possibility of at least partially replacing a failed engine with another engine, so that the

Motor vehicle driver perceives at least partial resistance.

It can particularly preferably be provided that the respective belt drive is prestressed between the respective motor and the steering spindle. The

Preload reduces the play between the components and at the same time leads to quiet operation of the feedback actuator.

In the following, the invention is explained by way of example with reference to the attached drawings using a preferred exemplary embodiment, the features shown below being able to represent an aspect of the invention both individually and in combination. It shows:

1: a schematic sectional view of a feedback actuator according to a first embodiment of the invention with a gear,

2: a schematic view of a cyclobelt transmission

1 according to FIG.

3: a view of a detail from FIGS. 3 and

4 shows a schematic sectional view of a feedback actuator according to a second embodiment of the invention with a belt system.

FIG. 1 thus shows a feedback actuator 10 for a steering device with a defined steering torque L, with an outer housing arrangement 12, comprising a steering spindle 14 for coupling to a steering wheel 16, the steering spindle 14 around its Longitudinal axis L is rotatably mounted in the housing arrangement 12, a bearing 18 for mounting the steering spindle 14, one arranged along the longitudinal axis L.

Friction element 20 for generating a basic friction of the feedback actuator 10, a locking device 22 for functions that require an active actuating torque greater than a defined steering torque L of a motor 26, an angle sensor system 24 for determining the rotor position for the regulation of a motor 26 and at least a first one Motor 26 for actively setting an engine steering torque M in one

switched on operating state of a vehicle. The feedback actuator 10 has a steering resistance system 28 for providing the defined steering torque L on the steering wheel 16, the motor steering torque M of the at least one motor 26 being smaller than the defined steering torque L for perception by one

Motor vehicle driver. Because of the compensation by the steering resistance system 28 in order to adjust the motor steering torque M to the amount of the defined steering torque L, the at least one motor 26 can be made more compact compared to a motor without this steering resistance system 28. This advantageously reduces the installation space required and can also reduce the energy requirement for the system.

As a particularly advantageous solution for a compact design, it has been found, as shown in FIGS. 1 and 2, that the steering resistance system 28 is a transmission.

In particular, the transmission can have a gear ratio of 50: 1 up to and including 70: 1, preferably essentially 60: 1. Such a transmission ratio has proven to be advantageous, on the one hand, to enable a compact design and, on the other hand, to allow a construction that is as gentle as possible on the components.

According to an advantageous embodiment of the invention, it is not shown that the steering resistance system 28 has a transmission designed as a cycloidal transmission. An eccentric of a drive unit drives a cam disk, which rolls inside a fixed pin ring and carries pins of an output unit. This allows the most compact possible design, whereby the gearbox is also low-noise and low-wear with a uniform

Load distribution works. This enables a long service life.

As an alternative to the cycloidal transmission, it can be provided, as shown in FIG. 2, that the steering resistance system 28 has a transmission designed as a Cyclobelt transmission. This has the advantage of a particularly low-play design.

As shown by way of example in FIG. 2, the Cyclobelt transmission can preferably have a transmission input 30, which is indirectly or directly connected to the motor shaft and is designed as a sun gear, and has at least three

Planet wheels 32 is surrounded, which are spanned by a single belt 34, the belt 34 of a connected to the steering shaft 14 and

In particular, a gear output 36 designed as a ring gear is surrounded, the gear input 30 and the gear output 36 being arranged coaxially to one another. This arrangement of the components enables a uniform force distribution to take place, so that the component life is increased.

Furthermore, the transmission input 30 can preferably have an at least partially elastic sheathing on the outside for acoustic decoupling.

In order to transmit the torque as evenly as possible and also with little noise, the belt 34 according to FIG. 3 can have internal and external teeth 38, 40. 3 shows a section X of FIG. 2. In operation of the feedback actuator 10, according to this exemplary embodiment, there is a positive guidance between the planet gears 32 and the gear output 36, which is designed in particular as a ring gear. This enables the feedback actuator 10 to be designed with little play.

A further preferred embodiment of the feedback actuator 10 can be designed according to FIG. 4 such that the steering resistance system 28 has at least two motors 26a, 26b, preferably three motors 26a, 26b, 26c, which are also connected via a respective belt drive 42a, 42b, 42c the steering shaft 14 are connected. This further reduces the installation space required for each motor 26. In addition, this gives the possibility of a failed motor 26 by another motor 26 at least partially to replace, so that the motor vehicle driver perceives at least a partial resistance.

It can be particularly preferably provided that the respective belt drive 42a, 42b, 42c is prestressed between the respective motor 26a, 26b, 26c and the steering spindle 14. The preload reduces the play between the components and at the same time leads to quiet operation of the feedback actuator 10.

Reference list

10 feedback actuator

12 Housing arrangement

14 steering spindle

16 steering wheel

18 bearings

0 friction element

2 locking device

4 angle sensor system

6 engine

6a First engine

6b Second engine

26c third motor

28 steering resistance system

30 transmission input

32 planet gears

34 straps

36 transmission output

38 internal teeth

40 external teeth

42a belt drive of the first motor

42b belt drive of the second motor

42c belt drive of the third motor

L steering torque

Claims

claims

1. Feedback actuator (10) for a steering device with a defined

Steering torque (L), comprising an outer housing arrangement (12)

a steering spindle (14) for coupling to a steering wheel (16), the steering spindle (14) being mounted in the housing arrangement (12) so as to be rotatable about its longitudinal axis (L),

- a bearing (18) for mounting the steering spindle (14),

a friction element (20) arranged along the longitudinal axis (L) for generating a basic friction of the feedback actuator (10),

- A locking device (22) for functions that require an active actuating torque greater than a defined steering torque (L) of an engine (26),

- An angle sensor system (24) for determining the rotor position for the control of a motor (26) and

- at least one first motor (26) for actively setting an engine steering torque (M) in the switched-on operating state of a vehicle,

characterized,

that the feedback actuator (10) has a steering resistance system (28) for providing the defined steering torque (L) on the steering wheel (16), the

Motor steering torque (M) of the at least one motor (26) is smaller than the defined steering torque (L) for perception by a motor vehicle driver.

2. Feedback actuator (10) for a steering device according to claim 1, characterized in that the steering resistance system (28) is a transmission.

3. Feedback actuator (10) for a steering device according to claim 1 or 2, characterized in that the transmission has a gear ratio of 50: 1 up to and including 70: 1, preferably substantially 60: 1.

4. Feedback actuator (10) for a steering device according to one of the preceding claims, characterized in that the steering resistance system (28) has a transmission designed as a cycloidal transmission.

5. Feedback actuator (10) for a steering device according to one of the preceding claims, characterized in that the steering resistance system (28) has a transmission designed as a Cyclobelt transmission.

6. Feedback actuator (10) for a steering device according to claim 5, characterized in that the cyclobelt transmission has a directly or indirectly connected to the motor shaft and designed as a sun gear transmission input (30) surrounded by at least three planet wheels (32) , which are spanned by a single belt (34), the belt (34) being surrounded by a gear drive (36) connected to the steering spindle (14), the

Transmission input (30) and the transmission output (36) are arranged coaxially to one another.

7. Feedback actuator (10) for a steering device according to claim 6, characterized in that the transmission input (30) has an at least partially elastic sheathing on the outside for acoustic decoupling.

8. Feedback actuator (10) for a steering device according to claim 6 or 7, characterized in that the belt (34) is an inner and / or

External teeth (38, 40).

9. Feedback actuator (10) for a steering device according to one of the preceding claims, characterized in that the steering resistance system (28) has at least two motors (26a, 26b), preferably three motors (26a, 26b, 26c), which have a respective belt drive (42a, 42b, 42c) are connected to the steering spindle (14).

10. Feedback actuator (10) for a steering device according to claim 9, characterized in that the respective belt drive (42a, 42b, 42c) is biased between the respective motor (26a, 26b, 26c) and the steering spindle (14).