Steering angle sensor for a steer-by-wire steering gear of a motor vehicle

Abstract

The invention relates to a steering angle sensor (1) for a steer-by-wire steering gear of a motor vehicle, comprising a planetary gear (10), wherein a sun gear (12) of the planetary gear (10) is arranged concentrically with a rotational axis of a planetary gear carrier (14) of the planetary gear (10); and an inductive sensor arrangement (16) for determining an angle of rotation of a first body (18) connected in a rotationally fixed manner to the sun gear (12), wherein the inductive sensor arrangement (16) further comprises a second body (20) connected in a rotationally fixed manner to the planetary gear carrier (14) and a measured value acquisition device (22) arranged between the first body (18) and the second body (20), which is configured to determine a current angle of rotation of the first body (18) taking into account a transmission ratio of the planetary gear (10). The invention further relates to a steer-by-wire steering gear of a motor vehicle.

Description

[0001] The invention relates to a steering angle sensor for a steer-by-wire steering gear of a motor vehicle.

[0002] Furthermore, the invention relates to a steer-by-wire steering gear of a motor vehicle. State of the art

[0003] A rack and pinion actuator, together with a steering wheel actuator and corresponding software apps, form the steer-by-wire steering system. The rack and pinion actuator receives the digitally transmitted steering signal and adjusts the appropriate wheel position.

[0004] To enable precise wheel position adjustment, a steering angle sensor is provided near the rack. This sensor can, for example, detect the rotation of a ball screw of the rack actuator. The steering angle sensor has an interface to an output shaft of the rack actuator, allowing the steering angle sensor to detect the absolute position of the rack.

[0005] DE 195 06 938 A1 discloses a method and device for measuring the angle of a rotatable body, in particular a body rotatable by more than 360°. This rotatable body interacts with at least two other rotatable bodies, for example, gears, whose angular position is determined using two sensors. The angular position of the rotatable body is determined from the angular positions thus determined. To ensure clear results, all three rotatable bodies or gears must have a certain predeterminable number of teeth. The method and device can be used, for example, to determine the steering angle of a motor vehicle.

[0006] Such steering angle sensors have a two-part design, with respective parts being mounted separately from each other, i.e. the sensor housing is attached to the housing of the steering and the rotating part is attached to the output shaft of the rack actuator.

[0007] However, the two-part design has the disadvantage that when torque is applied by the rack actuator and / or by forces acting externally on the rack, a bending moment acting on the steering angle sensor can lead to a twisting of gears, in particular a planetary gear of a planetary gear of the steering angle sensor and thus to an inaccurate position determination of the steering angle.

[0008] Consequently, there is a need to improve existing steering angle sensors for a steer-by-wire steering gear of a motor vehicle so that a permanently precise steering angle determination is possible regardless of the forces acting on the steering angle sensor.

[0009] It is therefore an object of the invention to provide an improved steering angle sensor for a steer-by-wire steering gear of a motor vehicle, which enables a permanently precise steering angle determination regardless of forces acting on the steering angle sensor. Disclosure of the invention

[0010] The object is achieved according to the invention by a steering angle sensor for a steer-by-wire steering gear of a motor vehicle having the features of patent claim 1.

[0011] Furthermore, the object is achieved according to the invention by a steer-by-wire steering gear of a motor vehicle having the features of patent claim 13.

[0012] The invention relates to a steering angle sensor for a steer-by-wire steering gear of a motor vehicle.

[0013] The steering angle sensor comprises a planetary gear, wherein a sun gear of the planetary gear is arranged concentrically to a rotational axis of a planet gear carrier of the planetary gear.

[0014] Furthermore, the steering angle sensor comprises an inductive sensor arrangement for determining a rotational angle of a first body which is connected in a rotationally fixed manner to the sun gear, wherein the inductive sensor arrangement further comprises a second body which is connected in a rotationally fixed manner to the planetary gear carrier and a measured value acquisition device arranged between the first body and the second body, which is configured to determine a current rotational angle of the first body taking into account a transmission ratio of the planetary gear.

[0015] The invention further relates to a steer-by-wire steering gear of a motor vehicle.

[0016] The steer-by-wire steering gear comprises a steering angle sensor according to the invention and an output shaft connected to the steering angle sensor.

[0017] One idea of ​​the present invention is to enable a precise steering angle determination by providing the steering angle sensor with a planetary gear in which a sun gear is arranged concentrically to a rotational axis of a planetary gear carrier, wherein a current rotational angle of the first body connected to the sun gear can be determined taking into account a transmission ratio of the planetary gear.

[0018] The closed, one-piece sensor concept, which is simultaneously plugged onto the output shaft and centered and fastened on the outside of the housing, thus enables precise steering angle determination.

[0019] Furthermore, the invention enables the housing of the steering angle sensor to be attached to the steering housing, as well as the rotating part to the output shaft of the rack actuator. This allows for a one-piece design of the steering angle sensor, since all attachment points are located on the housing or the outside of the steering angle sensor.

[0020] Further embodiments of the present invention are the subject of the further subclaims and the following description with reference to the figures.

[0021] According to a preferred development of the invention, it is provided that the planet gear carrier and the sun gear are arranged relative to one another in such a way that the planet gear carrier and the sun gear are positioned relative to one another by at least partially radial and axial engagement.

[0022] The sun gear and the planet gear carrier can thus advantageously be joined together in a force-locking and / or form-locking manner.

[0023] According to a further preferred development of the invention, it is provided that the planet gear carrier is formed from a first plastic material, and wherein the sun gear is formed from a second plastic material different from the first plastic material.

[0024] By forming the sun gear and the planet gear carrier from different plastic materials, it can be advantageously achieved that they have optimal tribological properties.

[0025] According to a further preferred development of the invention, it is provided that the first body is overmolded by the first plastic material of the sun gear, and wherein the second body is overmolded by the second plastic material of the planet gear carrier.

[0026] The overmolding of the first body, the sun gear, with the first plastic material and the overmolding of the second body, the planet gear carrier, with the second plastic material has the effect of ensuring that the respective bodies are rotationally fixedly connected to the plastic material of the sun gear or planet gear carrier. This ensures that the angle of rotation of the sun gear or planet gear carrier exactly corresponds to the angle of rotation of the body connected to the sun gear or planet gear carrier.

[0027] According to a further preferred development of the invention, it is provided that the first body and the second body are positioned and guided relative to one another in such a way that a distance between the first body and the second body relative to the measured value detection device is constant, in particular during operation of the steering angle sensor.

[0028] Due to the inductive measuring principle of the first body and the second body, a constant distance to the data acquisition device is crucial to enable reliable data acquisition.

[0029] According to a further preferred development of the invention, it is provided that the planetary gear has a transmission ratio of greater than or equal to one, in particular a slow transmission ratio.

[0030] One rotation of the sun gear thus results in fewer revolutions of each planetary gear. This scales the permissible angular error with the gear ratio, making the sensor less sensitive to backlash and tolerances.

[0031] According to a further preferred development of the invention, it is provided that the sun gear has an interface with a complementary shape to an output shaft that can be connected to the steering angle sensor, or wherein the sun gear is connected to an interface with a complementary shape to an output shaft that can be connected to the steering angle sensor.

[0032] This advantageously ensures that the steering angle sensor can be easily plugged onto the output shaft and that a positive and / or non-positive connection is provided between the steering angle sensor and the output shaft.

[0033] According to a further preferred development of the invention, it is further provided that the sun gear has a substantially elastic hub material.

[0034] This advantageously enables low joining forces of the sun gear, since the entire sensor assembly and the steering angle sensor are joined via the closed housing.

[0035] According to a further preferred development of the invention, it is provided that the steering angle sensor has a flexible housing membrane which is designed to transmit a joining force for connecting the steering angle sensor to the output shaft connectable to the steering angle sensor to the sun gear.

[0036] This makes it possible to apply the joining forces via an elastic housing membrane, which deforms slightly when subjected to axial force and rests against the sun gear, thereby enabling a direct flow of force through the sun gear to the interface.

[0037] According to a further preferred development of the invention, the sun gear has radial internal teeth designed to accommodate radial external teeth of the output shaft connectable to the steering angle sensor. This enables efficient mounting of the sun gear onto the output shaft.

[0038] According to a further preferred development of the invention, a housing interface of the steering angle sensor is designed to position and / or fix the steering angle sensor relative to a steering gear housing. This enables precise positioning of the steering angle sensor relative to the steering gear housing.

[0039] According to a further preferred development of the invention, a sleeve is positively mounted in a hub of the sun gear, which sleeve is designed to transmit torque from the output shaft to the sun gear when the output shaft, which can be connected to the steering angle sensor, is inserted. The sleeve can thus advantageously be joined to the output shaft in a positively locking manner.

[0040] According to a further preferred embodiment of the invention, the sun gear is formed as a single piece from a 3K material, in particular Elastolan. The use of Elastolan offers the advantage that the sun gear exhibits good flexibility while simultaneously providing efficient power transmission and minimal play relative to the output shaft.

[0041] The features of the steering angle sensor for a steer-by-wire steering gear of a motor vehicle described herein are equally applicable to the steer-by-wire steering gear of a motor vehicle and vice versa. Short description of the drawings

[0042] For a better understanding of the present invention and its advantages, reference is now made to the following description in conjunction with the accompanying drawings.

[0043] The invention is explained in more detail below using exemplary embodiments which are shown in the schematic illustrations of the drawings.

[0044] They show: Fig. 1 is an exploded view of a steering angle sensor for a steer-by-wire steering gear of a motor vehicle according to a preferred embodiment of the invention; Fig. 2 is a longitudinal sectional view of the steering angle sensor for the steer-by-wire steering gear of the motor vehicle according to the preferred embodiment of the invention; and Fig. 3 a schematic representation of the steering angle sensor for the steer-by-wire steering gear of the motor vehicle according to the preferred embodiment of the invention.

[0045] Unless otherwise indicated, like reference numerals refer to like elements in the drawings. Detailed description of the embodiments

[0046] This is Fig. The steering angle sensor 1 shown in Figure 1 for a steer-by-wire steering gear of a motor vehicle comprises a planetary gear 10, wherein a sun gear 12 of the planetary gear 10 is arranged concentrically to a rotational axis of a planet gear carrier 14 of the planetary gear 10.

[0047] Furthermore, the steering angle sensor 1 comprises an inductive sensor arrangement 16 for determining a rotation angle of a first body 18 which is connected in a rotationally fixed manner to the sun gear 12.

[0048] The inductive sensor arrangement 16 further comprises a second body 20 which is connected in a rotationally fixed manner to the planetary gear carrier 14 and a measured value acquisition device 22 arranged between the first body 18 and the second body 20, which is configured to determine a current angle of rotation of the first body 18 taking into account a transmission ratio of the planetary gear 10.

[0049] The planet gear carrier 14 and the sun gear 12 are arranged relative to one another in such a way that the planet gear carrier 14 and the sun gear 12 are positioned relative to one another by at least partially radial and axial engagement.

[0050] The planetary gear carrier 14 is also formed from a first plastic material. The sun gear 12, in turn, is formed from a second plastic material that differs from the first plastic material.

[0051] Furthermore, the first body 18 is overmolded with the first plastic material of the sun gear 12. The second body 20 is in turn overmolded with the second plastic material of the planet gear carrier 14.

[0052] The first body 18 and the second body 20 are positioned and guided relative to one another in such a way that a distance between the first body 18 and the second body 20 relative to the measured value detection device 22 is constant, in particular during operation of the steering angle sensor 1.

[0053] The planetary gear 10 has a gear ratio greater than or equal to one, in particular a slow gear ratio.

[0054] The steering angle sensor 1 further comprises a plurality of planetary gears 28, which are held in position by the planetary gear carrier 14. A housing of the steering angle sensor 1 comprises a first housing part 30, a second housing part 32, and a housing cover 34. The first housing part 30 extends longitudinally over the entire length of the planetary gear 10.

[0055] Fig. 2 shows a longitudinal sectional view of the steering angle sensor for the steer-by-wire steering gear of the motor vehicle according to the preferred embodiment of the invention.

[0056] The steer-by-wire steering gear of the motor vehicle comprises the steering angle sensor 1 according to the invention and an output shaft 26 connected to the steering angle sensor 1.

[0057] The sun gear 12 has an interface 24 with a complementary shape to an output shaft 26 connectable to the steering angle sensor 1. Alternatively, the sun gear 12 can be connected, for example, to an interface 24 with a complementary shape to an output shaft 26 connectable to the steering angle sensor 1.

[0058] The sun gear 12 also has a substantially elastic hub material.

[0059] The sun gear 12 further has a radial internal toothing which is designed to receive a radial external toothing of the output shaft 26 which can be connected to the steering angle sensor 1.

[0060] The steering angle sensor 1 may alternatively further comprise a flexible housing membrane which is designed to transmit a joining force for connecting the steering angle sensor 1 to the output shaft 26 connectable to the steering angle sensor 1 to the sun gear 12.

[0061] Furthermore, alternatively, a sleeve can be positively mounted in a hub of the sun gear 12, which sleeve transmits a torque from the output shaft 26 to the sun gear 12 in an inserted state of the output shaft 26 connectable to the steering angle sensor 1.

[0062] The sun gear 12 is preferably made in one piece from a 3K material, in particular Elastolan.

[0063] Fig. 3 shows a schematic representation of the steering angle sensor for the steer-by-wire steering gear of the motor vehicle according to the preferred embodiment of the invention.

[0064] The steering angle sensor further comprises an interface 36 of a sensor housing to a (in Fig. 3 (not shown) steering gear housing. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 195 06 938 A1

[0005]

Claims

[1] Steering angle sensor (1) for a steer-by-wire steering gear of a motor vehicle, comprising: a planetary gear (10), wherein a sun gear (12) of the planetary gear (10) is arranged concentrically to a rotational axis of a planet gear carrier (14) of the planetary gear (10); and an inductive sensor arrangement (16) for determining a rotation angle of a first body (18) connected to the sun gear (12) in a rotationally fixed manner, wherein the inductive sensor arrangement (16) further comprises a second body (20) connected to the planet gear carrier (14) in a rotationally fixed manner and a measured value detection device (22) arranged between the first body (18) and the second body (20), which is designed to to determine a current angle of rotation of the first body (18) taking into account a transmission ratio of the planetary gear (10). [2] Steering angle sensor according to claim 1, wherein the planetary gear carrier (14) and the sun gear (12) are arranged relative to one another in such a way that the planetary gear carrier (14) and the sun gear (12) are positioned relative to one another by at least partially radial and axial engagement. [3] Steering angle sensor according to claim 1 or 2, wherein the planetary gear carrier (14) is formed from a first plastic material, and wherein the sun gear (12) is formed from a second plastic material different from the first plastic material. [4] Steering angle sensor according to claim 3, wherein the first body (18) is overmolded by the first plastic material of the sun gear (12), and wherein the second body (20) is overmolded by the second plastic material of the planet gear carrier (14). [5] Steering angle sensor according to one of the preceding claims, wherein the first body (18) and the second body (20) are positioned and guided relative to one another in such a way that a distance between the first body (18) and the second body (20) relative to the measured value detection device (22) is constant, in particular during operation of the steering angle sensor (1). [6] Steering angle sensor according to one of the preceding claims, wherein the planetary gear (10) has a gear ratio greater than or equal to one, in particular a slow gear ratio. [7] Steering angle sensor according to one of the preceding claims, wherein the sun gear (12) has an interface (24) with a complementary shape to an output shaft (26) connectable to the steering angle sensor (1) or wherein the sun gear (12) is connected to an interface (24) with a complementary shape to an output shaft (26) connectable to the steering angle sensor (1). [8] Steering angle sensor according to one of the preceding claims, wherein the sun gear (12) has a substantially elastic hub material. [9] Steering angle sensor according to one of claims 1 to 7, wherein the steering angle sensor (1) has a flexible housing membrane which is designed to transmit a joining force for connecting the steering angle sensor (1) to the output shaft (26) connectable to the steering angle sensor (1) to the sun gear (12). [10] Steering angle sensor according to one of claims 1 to 7, wherein the sun gear (12) has a radial internal toothing which is designed to receive a radial external toothing of the output shaft (26) connectable to the steering angle sensor (1). [11] Steering angle sensor according to one of claims 1 to 7, wherein a sleeve is positively mounted in a hub of the sun gear (12), which sleeve is designed to transmit a torque from the output shaft (26) to the sun gear (12) in an inserted state of the output shaft (26) connectable to the steering angle sensor (1). [12] Steering angle sensor according to one of the preceding claims, wherein the sun gear (12) is formed in one piece from a 3K material, in particular Elastolan. [13] Steering angle sensor according to one of the preceding claims, wherein a housing interface (36) of the steering angle sensor (1) is designed to position and / or fix the steering angle sensor (1) to a steering gear housing. [14] Steer-by-wire steering gear of a motor vehicle, comprising: a steering angle sensor (1) according to one of claims 1 to 12; and an output shaft (26) connected to the steering angle sensor (1).

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