DE102019118396A1 - Manual force actuator with a speed conversion system for a rotation angle sensor system - Google Patents

Abstract

The invention relates to a manual force actuator (10) for a steer-by-wire steering system of a vehicle, having an outer housing arrangement (12), an electric motor (14), the electric motor (14) on the housing arrangement in a rotationally fixed manner along the longitudinal axis (L) (12) is arranged, at least one steering spindle (16) with a longitudinal axis (L) for receiving a steering torque of a steering wheel (18), wherein the steering spindle (16) is rotatably mounted about the longitudinal axis (L) in the housing arrangement (12), and wherein the steering spindle (16) is at least indirectly connected to the electric motor (14) for transmitting a torque (D), at least one bearing (20a, 20b) for the rotatable mounting of the steering spindle (16) in the housing arrangement (12), a rotation angle sensor system (22) for detecting the angle of rotation, the manual force actuator (10) having a speed conversion system (24) for diverting an input speed (n1) of the steering spindle (16) into an output speed (n2) of the rotation angle sensor system (22) Ktierenden rotary body (26).

Description

The invention relates to a manual force actuator for a steer-by-wire steering system of a vehicle according to claim 1. The invention also relates to a speed conversion system for the manual force actuator.

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 of an input unit. This causes the rotation of a steering spindle 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 that detect the steering command and output a determined electrical control signal to a steering actuator, which by means of an electric actuator sets a corresponding steering angle of the wheels.

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

In order to generate a realistic driving experience, it is known in the prior art to record parameters such as vehicle speed, steering angle, steering reaction torque and the like from an actual current driving situation or to calculate them in a simulation, and from these with a manual force actuator through a feedback signal to form corresponding torque generated by an electric motor. For this purpose, the manual force actuator comprises an actuating drive serving as a manual torque or steering wheel actuator. Thus, depending on the feedback signal, a restoring torque or torque corresponding to the real reaction torque is coupled into the steering wheel via the steering spindle. Such systems, also known as “force feedback” systems, give the driver the impression of a real driving situation as with conventional steering, which facilitates an intuitive reaction.

Steer-by-wire steering systems are generally known, for example each with an input unit which has a manual force actuator driven by an electric motor with a housing arrangement. 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 coupled directly to the steering spindle, so the motor torque is identical to the manual torque coupled into the steering spindle. The motor unit is flanged axially to the casing unit with respect to the longitudinal axis and the motor shaft is connected to the steering spindle mounted in the casing unit via a coupling.

An essential parameter for controlling the manual force actuator is, in addition to parameters related to the driving situation, a steering torque that is generated by a steering wheel or a driver. The intensity of the steering torque is detected in the steering train and transmitted to control electronics and the electric motor for applying a steering resistance to the steering spindle. In order to generate a steering resistance that is as realistic as possible through a torque, it is necessary to detect the steering torque and the torque counteracting by the electric motor as precisely as possible in order to give the driver a balanced steering feel.

Another essential parameter for controlling the manual force actuator is the precise detection of the angle of rotation or the speed of the steering spindle for transmission to the electric steering. In order to achieve the necessary precision, high-resolution and cost-intensive rotation angle sensor systems are used. These usually detect in-line with the steering spindle. This means that the angle of rotation or the speed of rotation of the steering spindle or of a spindle that is non-rotatable and coaxial with respect to the steering spindle is detected. Rotation angle sensor systems required in this way are costly in relation to the detection accuracy because of the high resolution.

The task of the current development is to develop a manual force actuator for a steer-by-wire steering system that has a compact design and enables inexpensive and reliable rotation angle detection of a steering spindle.

The object is achieved according to the invention by a manual force actuator for a steer-by-wire steering system of a vehicle with the features of claim 1 and a speed conversion system for a manual force actuator with the features of claim 10. Preferred embodiments of the invention are in the dependent claims and the following Description given, each individually or in combination can represent an aspect of the invention.

The invention thus relates to a manual force actuator for a steer-by-wire steering system of a vehicle
an outer housing assembly,
an electric motor, the electric motor being non-rotatably arranged on the housing arrangement along the longitudinal axis,
at least one steering spindle with a longitudinal axis for receiving a steering torque of a steering wheel, wherein the steering spindle is rotatably mounted about the longitudinal axis in the housing arrangement, and wherein the steering spindle is at least indirectly connected to the electric motor for transmitting a torque,
at least one bearing for the rotatable mounting of the steering spindle in the housing arrangement,
a rotation angle sensor system for rotation angle detection,
wherein the manual force actuator has a speed conversion system with a rotating body, wherein the speed conversion system is designed to divert an input speed of the steering spindle into an output speed of the rotating body to be detected by the rotation angle sensor system.

The object is thus achieved according to the invention in particular through the use of a speed conversion system. Thus, the detection by the rotation angle sensor system no longer takes place directly on the basis of the rotation of the steering spindle, but indirectly on the basis of the rotation of the steering spindle, namely on a rotary body which has a higher speed than the steering spindle. It has been found that this allows the rotation angle sensor system to be selected in a variable manner. The inventive solution thus provides a speed conversion system, in particular designed as a gear, which increases the speed of the rotating body, the speed of which is detected by the rotation angle sensor system on the basis of the rotation angle. As a result, the angle of rotation sensor system can be used with the same accuracy with a lower resolution compared to the prior art. This is considerably cheaper. Alternatively, the rotation angle sensor system can be used with the same resolution, so that the accuracy is increased.

In other words, the detection of the angle of rotation or the rotational speed means that the rotation is detected. This means that a partial, ie not a complete, rotation about the rotating body's own axis of rotation can also be detected.

According to a preferred embodiment of the invention, it is provided that the rotary body has a plurality of incremental encoders that are uniformly distributed around the circumference and are to be detected by the rotation angle sensor system. The even distribution enables a higher accuracy of the detected angle of rotation or speed.

According to a preferred embodiment of the aforementioned embodiment, it is provided that the rotation angle sensor system optically detects the incremental encoder. This is a reliable and inexpensive way to detect rotation.

According to a preferred embodiment of the invention it is provided that the transmission ratio i = n1 / n2 from the input speed of the steering spindle to the output speed of the rotating body is between 1/2 up to and including 1/20, preferably 1/3, inclusive. Generally recognized, the ratio of the speed of the prime mover (gear input) and the speed of the driven machine (gear output) is defined as the transmission ratio. If i> 1, the speed is reduced, but the transmitted torque is increased. Here i> 1 is referred to as reduction or translation into slow speed i <1 as translation into fast. The gear ratio i = n1 / n2 between 1/2 up to and including 1/20, preferably 1/3, is thus a high speed gear ratio. This enables the preferred angle of rotation sensor system to require a lower resolution compared to angle of rotation sensor systems in conventional manual force actuators or to have a higher accuracy with the same resolution compared to angle of rotation sensor systems in conventional manual force actuators. The aforementioned areas have proven particularly advantageous in order to enable inexpensive and sufficiently accurate detection.

According to a preferred embodiment of the invention it is provided that
the speed conversion system is a spur gear system. This is a reliable and at the same time inexpensive to manufacture speed conversion system.

According to an alternative preferred embodiment of the invention it is provided that the speed conversion system is a belt drive system. This is a reliable and at the same time inexpensive to manufacture speed conversion system.

Speed conversion systems that act similarly to the aforementioned speed conversion systems are preferred.

According to a preferred embodiment of the invention it is provided that the speed conversion system is arranged between the steering spindle and the rotation angle sensor system. It has been found that this arrangement is a allows a compact arrangement that ensures reliable detection.

According to a preferred embodiment of the invention it is provided that the rotating body has a star-shaped cross section. Star-shaped means in the shape of a star. Specifically, this means that the preferred cross section has at least partially, preferably continuously, alternating radial superscripts and subscripts. These superscripts and subscripts can be designed as pointed points or as slightly curved points.

According to an alternative preferred embodiment of the invention it is provided that the axis of rotation of the rotary body is arranged parallel to the longitudinal axis of the steering spindle. It has been found that this arrangement enables a compact arrangement that ensures reliable detection.

The invention also relates to a speed conversion system for a manual force actuator with at least one of the preceding features, characterized by the features of the speed conversion system according to at least one of the preceding claims.

• 1: eine schematische Schnittansicht eines beispielhaften Handkraftaktuators,
• 2: eine schematische Schnittansicht eines Handkraftaktuators gemäß einer beispielhaften Ausgestaltung der Erfindung,
• 3: eine Lenkspindel mit einem Drehwinkelsensorsystem für einen Handkraftaktuator nach 1, und
• 4: zwei bevorzugte Ausführungsformen eines Drehkörpers mit einem Drehwinkelsensorsystem für einen Handkraftaktuator nach 2.

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

• 1 : a schematic sectional view of an exemplary manual force actuator,
• 2 : a schematic sectional view of a manual force actuator according to an exemplary embodiment of the invention,
• 3 : a steering spindle with a rotation angle sensor system for a manual force actuator according to 1 , and
• 4th : two preferred embodiments of a rotating body with a rotation angle sensor system for a manual force actuator according to 2 .

• eine Gehäuseanordnung 12, umfassend insbesondere folgende Komponenten
• einen Elektromotor 14 zum aktiven Stellen eines definierten Lenkwiderstands, beispielsweise von etwa zehn Newtonmeter,
• mindestens eine Lenkspindel 16 zur Drehmomentaufnahme eines Lenkrads 18, mindestens ein Lager 20a, 20b, vorzugsweise zwei Lager 20a, 20b, zur Lagerung der Lenkspindel 16,
• ein Drehwinkelsensorsystem 22 zur Rotorlangenermittlung der Lenkspindel 16 für eine Regelung des Handkraftaktuators 10,
• beispielhaft eine Sperre 30 für Systemausfall und Zusatzfunktionen, die ein aktives Stellmoment als der Lenkwiderstand erfordern,
• beispielhaft ein Reibelement 32 zur Erzeugung einer Grundreibung im System, zur Vermeidung einer synthetischen Haptik, und
• beispielhaft ein Getriebe 34 zum Aufskalieren eines Motormoments, um ein gefordertes Lenkmoment, beispielsweise von etwa zehn Newtonmeter, zu ermöglichen. Das Lenkmoment kann somit beispielsweise entweder direkt vom Elektromotor 14 oder durch das Getriebe 34 zur Verfügung gestellt werden.

The 1 Fig. 10 shows an exemplary embodiment of a manual force actuator 10 . The exemplary manual force actuator 10 has for direct drive steering:

• a housing assembly 12 , comprising in particular the following components
• an electric motor 14th for actively setting a defined steering resistance, for example about ten newton meters,
• at least one steering spindle 16 to absorb the torque of a steering wheel 18th , at least one warehouse 20a , 20b , preferably two camps 20a , 20b , for mounting the steering spindle 16 ,
• a rotation angle sensor system 22nd for determining the rotor length of the steering spindle 16 for regulating the manual force actuator 10 ,
• an example of a lock 30th for system failure and additional functions that require an active control torque as the steering resistance,
• for example a friction element 32 to generate a basic friction in the system, to avoid synthetic haptics, and
• for example a transmission 34 for scaling up an engine torque in order to enable a required steering torque, for example of about ten Newton meters. The steering torque can thus either come directly from the electric motor, for example 14th or through the gearbox 34 to provide.

In particular, it is provided that the electric motor 14th along the longitudinal axis L. at one end or end region of the housing arrangement 12 non-rotatably on the housing assembly 12 is arranged

The housing arrangement shown 12 includes as in 1 a single housing module shown as an example. However, a multi-part housing body is also possible.

Furthermore, in 1 no speed conversion system 24 shown. Nevertheless, the basic structure of the manual force actuator 10 also on a manual force actuator 10 with a speed conversion system 24 after 2 be transmitted.

2 shows a preferred manual force actuator 10 for a steer-by-wire steering system of a vehicle, comprising
an outer housing assembly 12 ,
an electric motor 14th , the electric motor 14th along the longitudinal axis L. non-rotatably on the housing assembly 12 is arranged
at least one steering spindle 16 with a longitudinal axis L. for receiving a steering torque of a steering wheel 18th , with the steering shaft 16 around the longitudinal axis L. rotatable in the housing assembly 12 is mounted, and wherein the steering shaft 16 for transmitting a torque D. at least indirectly with the electric motor 14th connected is,
at least one warehouse 20a , 20b for the rotatable mounting of the steering spindle 16 in the housing arrangement 12 ,
a rotation angle sensor system 22nd for rotation angle detection,
being the hand force actuator 10 a speed conversion system 24 with a rotating body 26th having, and wherein the speed conversion system 24 is designed to divert an input speed n1 the steering shaft 16 , please refer 3 , into an output speed n2 by the rotation angle sensor system 22nd rotating body to be detected 26th , please refer 4a and 4b .

3 shows one by the rotation angle sensor system 22nd steering spindle to be detected 16 for a manual force actuator 10 without speed conversion system 24 , for example after 1 . The exemplary steering spindle 16 twelve circumferentially evenly distributed and by the rotation angle sensor system 22nd incremental encoder to be detected 28 on. The steering shaft 16 rotates at an input speed n1 so that the rotation angle sensor system 22nd Must have a resolution that is appropriate to the rotation of the steering shaft 16 or the incremental encoder 28 to be detected in real time.

According to the 4a and 4b it is provided that
the rotating body 26th a plurality of circumferentially evenly distributed and by the rotation angle sensor system 22nd increment encoder to be detected 28 having. The rotating body has 26th after 4a for example four incremental encoders 28 and the rotating body 26th after 4b for example twelve incremental encoders 28 on.

The angle of rotation sensor system is corresponding to this 22nd formed the rotation of the steering shaft 16 or the incremental encoder 28 to be detected in real time. This further means that the rotation angle sensor system 22nd after 4a requires a lower resolution than the rotation angle sensor system 22nd after 4b .

In particular, it is provided that the rotation angle sensor system 22nd the incremental encoder 28 optically detected.

According to a preferred embodiment of the invention it is provided that the transmission ratio i = n1 / n2 from the input speed n1 the steering shaft 16 to the output speed n2 of the rotating body 26th between 1/2 up to and including 1/20, preferably 1/3, inclusive.

If you look at the 4a this means that with a rotating body 26th with, for example, four incremental encoders 28 and an exemplary transmission ratio of i = n1 / n2 = 1/3 per one revolution of a steering shaft 16 three turns of the rotating body 26th respectively. If an incremental encoder 28 corresponds to one bit, for example, when the rotating body rotates three times 26th with its four incremental encoders 28 detected a total of 12 bits. The relatively small number of incremental encoders 28 requires a rotation angle sensor system 22nd with relatively low resolution. In contrast, the steering spindle exemplarily 16 after 3 circumferentially twelve incremental encoders 28 on. These twelve incremental encoders 28 however, are during a single revolution of the steering shaft 16 to detect, so that the rotation angle sensor system 22nd compared to the embodiment according to 4a a higher resolution is required.

If you look at the 4b this means that with a rotating body 26th with, for example, twelve incremental encoders 28 and an exemplary transmission ratio of i = n1 / n2 = 1/3 per one revolution of a steering shaft 16 three turns of the rotating body 26th respectively. If an incremental encoder 28 corresponds to one bit, for example, when the rotating body rotates three times 26th with its twelve incremental encoders 28 detected a total of 36 bits. The number of exemplary incremental encoders corresponds to this 28 after 4b the number of exemplary incremental encoders 28 after 3 so that the rotation angle sensor system 22nd should have the same minimum resolution. However, after 3 12 bits and after 4b 36 bits are detected, so the accuracy of the detection result in the embodiment according to 4b is higher.

According to a preferred embodiment of the invention, not shown, it is provided that the speed conversion system 24 is a spur gear system.

According to an alternative preferred embodiment of the invention is according to 2 provided that the speed conversion system 24 is a belt drive system.

According to a preferred embodiment of the invention is according to 2 provided that the speed conversion system 24 between the steering shaft 16 and the rotation angle sensor system 22nd is arranged.

According to a preferred embodiment of the invention is according to the 4a and 4b provided that the rotating body 26th has a star-shaped cross section.

According to a preferred embodiment of the invention is according to 2 provided that the axis of rotation D. of the rotating body 26th parallel to the longitudinal axis L. the steering shaft 16 is arranged

List of reference symbols

10

Manual force actuator

12

Housing arrangement

14th

Electric motor

16

Steering shaft

18th

steering wheel

20a

warehouse

20b

warehouse

22nd

Rotation angle sensor system

24

Speed conversion system

26th

Rotating body

28

Incremental encoder

30th

Lock

32

Friction element

34

transmission

L.

Longitudinal axis of the steering shaft

n1

Input speed

n2

Output speed

D.

Axis of rotation of the rotating body

Claims (10)

Manual power actuator (10) for a steer-by-wire steering system of a vehicle, comprising - an outer housing arrangement (12), - an electric motor (14), the electric motor (14) on the housing arrangement (12) in a rotationally fixed manner along the longitudinal axis (L) ) is arranged, - at least one steering spindle (16) with a longitudinal axis (L) for receiving a steering torque of a steering wheel (18), wherein the steering spindle (16) is rotatably mounted about the longitudinal axis (L) in the housing arrangement (12), and wherein the steering spindle (16) for transmitting a torque (D) is at least indirectly connected to the electric motor (14), - at least one bearing (20a, 20b) for the rotatable mounting of the steering spindle (16) in the housing arrangement (12), - a Angle of rotation sensor system (22) for detecting the angle of rotation, characterized in that the manual force actuator (10) has a speed conversion system (24) with a rotating body (26), the speed conversion system (24) being designed to translate an input speed (n1) of the steering spindle (16) into a higher output speed (n2) of the rotating body (26) to be detected by the rotation angle sensor system (22). Manual force actuator (10) Claim 1 , characterized in that the rotating body (26) has a plurality of incremental encoders (28) which are uniformly distributed around the circumference and are to be detected by the rotation angle sensor system (22). Manual force actuator (10) Claim 2 , characterized in that the rotation angle sensor system (22) optically detects the incremental encoder (28). Manual force actuator (10) according to at least one of the preceding claims, characterized in that the transmission ratio i = n1 / n2 from the input speed (n1) of the steering spindle (16) to the output speed (n2) of the rotating body (26) between 1/2 to including 1/20, preferably 1/3. Manual force actuator (10) according to at least one of the preceding claims, characterized in that the speed conversion system (24) is a spur gear system. Manual force actuator (10) according to at least one of the Claims 1 to 4th , characterized in that the speed conversion system (24) is a belt drive system. Manual force actuator (10) according to at least one of the preceding claims, characterized in that the speed conversion system (24) is arranged between the steering spindle (16) and the rotation angle sensor system (22). Manual force actuator (10) according to at least one of the preceding claims, characterized in that the rotating body (26) has a star-shaped cross section. Manual force actuator (10) according to at least one of the Claims 1 to 8th , characterized in that the axis of rotation (D) of the rotating body (26) is arranged parallel to the longitudinal axis (L) of the steering spindle (16). Speed conversion system (24) for a manual force actuator (10) according to at least one of the preceding claims, characterized by the features of the speed conversion system (24) according to at least one of the preceding claims.

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