CN111252135A

CN111252135A - Electromechanical steering assembly

Info

Publication number: CN111252135A
Application number: CN201911065393.3A
Authority: CN
Inventors: B·维博尔特-戈尔巴坚科
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2018-11-30
Filing date: 2019-11-04
Publication date: 2020-06-09
Also published as: DE102018130513A1

Abstract

The invention relates to an electromechanical steering assembly (1) for a motor vehicle, comprising a force feedback actuator (2) having a drive unit (4) which is operatively connected to a steering wheel connection (5) via a transmission (3), wherein the drive unit (4) has a drive shaft (6) for actuating the transmission (3) and the steering wheel connection (5) has an output shaft (7) operatively connected to the transmission (3). A drive shaft (6) of the drive unit (4) and a driven shaft (7) of the steering wheel connection (5) are arranged concentrically, wherein at least one first intermediate wheel (8a) is arranged in the energy flow between the drive unit (4) and the steering wheel connection (5).

Description

Electromechanical steering assembly

Technical Field

The invention relates to an electromechanical steering assembly for a motor vehicle, comprising a force feedback actuator having a drive unit which is operatively connected to a steering wheel connection via a transmission, wherein the drive unit has a drive shaft for actuating the transmission and the steering wheel connection has a driven shaft which is operatively connected to the transmission.

Background

Modern motor vehicle steering axles usually have a so-called steer-by-wire system, which receives the driver's steering commands as in conventional mechanical steering by manually turning the steering wheel. The adjustment of the steering angle of the wheels to be steered is carried out electromechanically by means of a steering angle sensor or torque sensor which detects a steering command input into the steering wheel and sends an electrical control signal determined therefrom to a steering actuator which at least indirectly adjusts the respective steering angle or steering angle of the wheels of the steered axle. Since the steering actuator is not directly mechanically connected to the steering wheel, no force feedback is initially provided on the steering wheel when the actuation of the steering actuator or the actuating module and the resulting adjustment of the steering angle of the wheels is carried out, but such a feedback force is in principle desirable. Due to the lack of haptic feedback, it is difficult for the driver to reliably know the current driving situation and to carry out a suitable steering operation, so that the handling of the vehicle and thus the driving safety are impaired.

In order to be able to implement a Force Feedback or a restoring torque (also referred to as Force-Feedback in english) also in an actuating module that is mechanically decoupled from the steering wheel, a Force Feedback actuator is provided, which is designed in such a way that a Force Feedback or a restoring torque is generated on the steering shaft or directly on the steering wheel, which Force Feedback or restoring torque provides the driver with a haptic Force Feedback. In other words, the driver is simulated with a known steering feel by adjusting the restoring torque on the steering wheel by means of the force feedback actuator.

DE 102013014122 a1 discloses a steering stop for a steer-by-wire system, which has a steering shaft for connection to a steering wheel. A worm gear is coupled to the steering shaft, wherein a longitudinal axis of the worm gear and a longitudinal axis of the steering shaft are arranged parallel to each other. The worm wheel cooperates with a worm and the worm is provided with a drive.

Disclosure of Invention

The object of the present invention is to further develop an electromechanical steering assembly and in particular to reduce the installation space required for the steering assembly. This object is achieved by an electromechanical steering assembly having the features of the preferred embodiments. Advantageous embodiments of the invention result from the following description and the drawing.

The invention relates to an electromechanical steering assembly for a motor vehicle, comprising a force feedback actuator having a drive unit which is operatively connected to a steering wheel connection via a transmission, wherein the drive unit has a drive shaft for actuating the transmission and the steering wheel connection has a driven shaft which is operatively connected to the transmission, wherein the drive shaft of the drive unit and the driven shaft of the steering wheel connection are arranged concentrically, wherein at least one first intermediate wheel is arranged in the energy flow between the drive unit and the steering wheel connection. The force feedback actuator can be connected, for example, to a control device, which sends commands to the force feedback actuator for generating a restoring torque (also referred to as force feedback) in order to generate or simulate the actual steering and driving feel for the driver of the motor vehicle in accordance with the driving situation.

The term "force feedback" is to be understood as a force feedback or restoring torque, wherein the restoring torque is generated on the steering wheel for providing the driver with a manually simulated tactile feedback about the momentary driving situation, which the driver desires in the case of a mechanical or hydraulic coupling between the steering wheel and the adjustment module in a conventional manner for adjusting the steering angle of the wheels. In other words, the driver is provided with a haptic signal generated by the force feedback actuator, by means of which the driver can assess the current driving situation and react to it.

Preferably, the force feedback actuator is connected to the steering wheel via a steering wheel connection, wherein, via the steering wheel connection or the steering shaft, on the one hand, a manual steering command of the driver is introduced into the force feedback actuator by turning the steering wheel, and, on the other hand, a restoring torque is transmitted from the force feedback actuator to the steering wheel in the opposite force path.

The concentric arrangement of the output shaft and the drive shaft has the advantage that the available installation space in the motor vehicle can be optimally utilized. In particular, the steering assembly may be configured to be relatively elongated, so that a so-called inline arrangement may be achieved in which the steering assembly of the present invention may be mounted within a steering tube. Furthermore, a higher transmission ratio can be achieved by means of the at least one intermediate wheel.

The term "operatively linked" is understood to mean: the two transmission elements, for example the two gears, can be directly connected to one another, or further transmission elements, for example one or more shafts or gears, can also be present between the two transmission elements. Two toothed wheels are provided, which are in toothed engagement with one another, for transmitting torque or rotational speed from one toothed wheel to the other. A "gear" is understood to mean a pinion, a ring gear and an intermediate wheel of a one-piece or multi-piece ring gear transmission.

Preferably, the gear has a first pinion which is connected to the drive shaft in a rotationally fixed manner, and a ring gear which is connected to the output shaft in a rotationally fixed manner. In other words, the ring gear is connected at least indirectly via a steering wheel connection to the steering wheel of the motor vehicle in a rotationally fixed manner, wherein the steering wheel connection is preferably at least in sections designed as a hollow shaft. A torque or a restoring torque and a rotational speed are transmitted between the drive shaft and the output shaft, wherein the transmission ratio is dependent on the diameter and the number of teeth of the interacting components.

In this case, the first intermediate wheel is preferably in toothed engagement with the first pinion and the ring gear. The pinion is rotationally driven by a drive unit via the drive shaft, wherein the ring gear is rotationally driven by a first intermediate wheel meshing with the first pinion. The torque or restoring torque generated by the drive unit thereby acts on the steering wheel and thus provides a haptic signal to the driver of the motor vehicle.

There is a so-called overlap or tooth profile overlap between the teeth of the first intermediate gear and the teeth of the pinion or ring gear. The degree of overlap corresponds here to the ratio of the length of the toothing to the pitch of the respective gear wheel, i.e. the respective pinion, intermediate wheel or ring gear. In order to achieve a continuous transmission of torque between the intermediate wheel and the first pinion or ring gear, the meshing length must be greater than the pitch, i.e. the distance between the two flanks on the same side on the pitch circle. Thereby, it is ensured that at least one tooth, preferably a plurality of teeth, is in a tooth fit. The greater the overlap, the better the acoustic properties of the transmission. In addition, damage may be reduced by a high degree of overlap, for example, the formation of pitting holes may be reduced.

Furthermore, it is preferred that the first intermediate wheel is rotatably mounted on a first bearing pin, which is arranged on the housing section of the drive unit in a rotationally fixed manner. The housing section of the drive unit is fixed in position, i.e., non-rotatably fixed, for example, to the chassis or body of the motor vehicle. The first intermediate wheel thereby rotates about the longitudinal axis of the first intermediate pin, which is fixed in position.

Furthermore, a first bearing element is preferably arranged on the first bearing pin for rotatably bearing the first intermediate wheel. The first bearing element can be a ball bearing or a roller bearing or other suitable bearing. The first bearing element ensures an axially fixed and rotatable arrangement of the first intermediate wheel on the first bearing pin.

According to an alternative embodiment, the first intermediate wheel is in toothed engagement with the first pinion, wherein the first intermediate wheel is connected in a rotationally fixed manner to a second pinion, which is in toothed engagement with a second intermediate wheel, wherein the second intermediate wheel is in toothed engagement with the ring gear. In other words, the axially adjacent first intermediate wheel and the second pinion together form a step gear which at least indirectly transmits torque and rotational speed between the first pinion and the ring gear. The first intermediate wheel preferably has a first diameter that is configured to be larger than a second diameter of the second pinion.

Preferably, the second intermediate wheel is rotatably mounted on a second bearing pin, which is arranged in a rotationally fixed manner on the housing section of the steering wheel connection. Preferably, the second bearing pin is arranged to be fixed on the steering wheel.

Furthermore, a second bearing element is preferably arranged on the second bearing pin for rotatably supporting the second intermediate wheel. Here, the second bearing element can also be a ball bearing or a roller bearing or other suitable bearings. The second bearing element ensures an axially fixed and rotatable arrangement of the second intermediate wheel on the second bearing pin

The invention comprises the technical teaching that the first pinion, the second pinion, the first intermediate wheel, the second intermediate wheel and/or the toothed ring have involute helical teeth. Involute helical teeth (involute-Verzahnung) refer to skewed involute teeth that use a small number of teeth up to only one tooth in order to achieve high transmission ratios in transmission stages having a plurality of parallel axes. The involute helical toothing can be used to reduce the number of gear stages and/or to increase the modulus to a multiple of its value. In this case, the respective involute helical toothing can be designed for a step-down or step-up transmission.

Furthermore, the drive unit is preferably designed as an electric motor. In this case, the force feedback actuator is in particular operatively connected to a steering wheel connection which is simultaneously designed as a drive shaft for manual input of a steering command and as a driven shaft for transmission of a restoring torque to the steering wheel.

Drawings

Further refinements of the invention are explained in detail below with reference to the two figures together with the description of two preferred embodiments of the invention.

Figure 1 shows a simplified schematic longitudinal section of an electromechanical steering assembly according to a first embodiment of the present invention; and

figure 2 shows a simplified schematic longitudinal section of an electromechanical steering assembly according to a second embodiment of the present invention.

Detailed Description

According to fig. 1 and 2, an electromechanical steering assembly 1 for a motor vehicle (not shown here) comprises a force feedback actuator 2 having a drive unit 4 which is operatively connected to a steering wheel connection 5 via a transmission 3. The drive unit 4 is designed as an electric motor which drives a drive shaft 6 and a first pinion 9a of the gear 3 connected thereto in a rotationally fixed manner, wherein the drive shaft 6 is rotatably mounted on a housing section 12 of the drive unit 4.

At a free end opposite the gear 3, the steering wheel connection 5 is connected at least indirectly to a steering wheel (not shown here) and has a driven shaft 7, which is operatively connected to the gear 3 and is connected in a rotationally fixed manner to a ring gear or ring gear 10 of the gear 3. The output shaft 7 is therefore designed in sections as a hollow shaft. Here, the drive shaft 6 of the drive unit 4 and the driven shaft 7 of the steering wheel connection 5 are arranged concentrically or coaxially.

Fig. 1 shows that a first intermediate wheel 8a is arranged in the power flow between the drive unit 4 and the steering wheel connection 5. The first intermediate wheel 8a is in toothed engagement with the first pinion 9a and the ring gear 10. The first intermediate wheel 8a is rotatably mounted by means of a first bearing element 13a on a first bearing pin 11a, which is arranged in a rotationally fixed manner on the housing section 12 of the drive unit 4. The housing section 12 is supported on the body (not shown here) of the motor vehicle and is therefore torsion-resistant. It is conceivable that for high drive torques a further intermediate wheel 8a can also be provided in the force feedback actuator 2.

According to fig. 2, a first intermediate wheel 8a and a second intermediate wheel 8b are arranged in the power flow between the drive unit 4 and the steering wheel connection 5. The first intermediate wheel 8a is in toothed engagement with the first pinion 9a, wherein the first intermediate wheel 8a is connected in a rotationally fixed manner to a second pinion 9b arranged axially adjacent thereto and thus forms a stepped wheel with different diameters. The second pinion 9b is in toothed engagement with a second intermediate wheel 8b, wherein the second intermediate wheel 8b is in toothed engagement with the ring gear 10, so that torque and rotational speed are transmitted from the drive shaft 6 of the drive unit 4 to the output shaft 7 of the steering wheel connection 5. A high overall transmission ratio can be achieved by the two interacting

intermediate wheels

8a,8 b.

The second intermediate wheel 8b is rotatably mounted by means of a second bearing element 13b on a second bearing pin 11b, which is arranged in a rotationally fixed manner on a housing section 14 of the steering wheel connection 5. In this example, the first pinion 9a and the first intermediate wheel 8a have involute helical teeth.

List of reference numerals

1 electromechanical steering assembly

2 force feedback actuator

3 Transmission device

4 drive unit

5 steering wheel connection part

6 drive shaft

7 driven shaft

8a,8b intermediate wheel

9a,9b pinion

10 ring gear

11a,11b bearing pin

12 housing section of a drive unit

13a,13b support element

14 housing section of a steering wheel connection.

Claims

1. An electromechanical steering assembly (1) for a motor vehicle, comprising a force feedback actuator (2) having a drive unit (4) which is operatively connected to a steering wheel connection (5) via a transmission (3), wherein the drive unit (4) has a drive shaft (6) for actuating the transmission (3) and the steering wheel connection (5) has an output shaft (7) which is operatively connected to the transmission (3),

characterized in that a drive shaft (6) of the drive unit (4) and a driven shaft (7) of the steering wheel connection (5) are arranged concentrically, wherein at least one first intermediate wheel (8a) is arranged in the energy flow between the drive unit (4) and the steering wheel connection (5).

2. Steering assembly (1) according to claim 1,

the transmission (3) is characterized by a first pinion (9a) which is connected to the drive shaft (6) in a rotationally fixed manner, and by a ring gear (10) which is connected to the output shaft (7) in a rotationally fixed manner.

3. Steering assembly (1) according to claim 2,

characterized in that the first intermediate wheel (8a) is in toothed engagement with the first pinion (9a) and the ring gear (10).

4. Steering assembly (1) according to any of the previous claims,

characterized in that the first intermediate wheel (8a) is rotatably mounted on a first bearing pin (11a) which is arranged in a rotationally fixed manner on a housing section (12) of the drive unit (4).

5. Steering assembly (1) according to claim 4,

characterized in that a first bearing element (13a) is arranged on the first bearing pin (11a) for rotatably supporting the first intermediate wheel (8 a).

6. Steering assembly (1) according to claim 2,

characterized in that the first intermediate wheel (8a) is in toothed engagement with the first pinion (9a), wherein the first intermediate wheel (8a) is connected in a rotationally fixed manner to a second pinion (9b) which is in toothed engagement with a second intermediate wheel (8b), wherein the second intermediate wheel (8b) is in toothed engagement with the ring gear (10).

7. Steering assembly (1) according to claim 6,

characterized in that the second intermediate wheel (8b) is rotatably mounted on a second bearing pin (11b) which is arranged in a rotationally fixed manner on a housing section (14) of the steering wheel connection (5).

8. Steering assembly (1) according to claim 7,

characterized in that a second bearing element (13b) is arranged on the second bearing pin (11b) for rotatably supporting the second intermediate wheel (8 b).

9. Steering assembly (1) according to one of the claims 6 to 8,

characterized in that said first pinion (9a), said second pinion (9b), said first intermediate wheel (8a), said second intermediate wheel (8b) and/or said ring gear (10) have involute helical teeth.

10. Steering assembly (1) according to any of the previous claims,

characterized in that the drive unit (4) is designed as an electric motor.