Rotation sensor for a steering system of a motor vehicle, and steering system for a motor vehicle

Abstract

The present invention relates to a rotation sensor (4) for a steering system (1) of a motor vehicle, the rotation sensor comprising a magnetic element (56), which can be rotated about a sensor axis (L), and a stator (5), which is fixed relative to the sensor axis (L) and has coaxially arranged stator elements (51, 52) having two axially spaced collecting portions (53, 54) between which a sensor element (6) is arranged, wherein the stator (5) and the sensor element (6) are arranged in a sensor housing (41). In order to allow for simpler assembly and to reduce the construction complexity, the invention proposes that the sensor element (6) is rotatably mounted relative to the stator (5) about a rotation axis (D) which is parallel to and radially spaced apart from the sensor axis (L).

Description

[0001] Rotation sensor for a steering system of a motor vehicle and steering system for a motor vehicle

[0002] State of the art

[0003] The invention relates to a rotation sensor for a steering system of a motor vehicle, comprising a magnetic element rotatable about a sensor axis and a stator fixed relative to the sensor axis, with coaxially arranged stator elements having two axially spaced collecting sections between which a sensor element is arranged. The stator and the sensor element are arranged in a sensor housing. A steering system with such a rotation sensor is also subject of the invention.

[0004] An electric rotation sensor is used in an electromechanical power steering system or a steer-by-wire steering system of a motor vehicle to detect a manual steering command. The rotation sensor detects the rotation of the steering shaft during manual operation of a steering handle, such as a steering wheel, and additionally or alternatively the manual steering torque applied to the steering shaft. This generates electrical control signals to actuate an electric steering drive, which causes the steered wheels to turn.

[0005] A generic rotary sensor can be designed as a rotary angle sensor, torque sensor or as a combined rotary angle and torque sensor and has a magnetic sensor arrangement, as described for example in WO 2020 / 174170 A1 or the

[0006] This is described in EP 3 040 698 A1. It comprises a magnetic element connected to the steering shaft and rotatable about a sensor axis, and a stator with two annular stator elements that coaxially enclose the magnetic element and are fixed relative to the sensor axis. Rotation of the magnetic element induces a characteristic magnetic flux in the stator elements. This flux is coupled via two magnetic collector sections connected to the stator elements to a magnetoelectric sensor element, which, for example, comprises at least one Hall or magnetoresistive (GMR) element, in which the detected magnetic flux is converted into an electrical signal.

[0007] In the generic design, the stator elements have axially spaced collecting sections, which preferably extend perpendicular to the sensor axis in the shape of an annular disk. At least one sensor element is arranged in the axial space between the collecting sections, through which the magnetic flux flows in the axial direction.

[0008] To mount the rotation sensor, the stator elements are fixed relative to the magnetic element, for example, on a steering shaft part or steering housing. To attach the sensor element, the current technology involves positioning and securing it from the outside by inserting it radially between the collecting sections.

[0009] The stator elements and the sensor element are housed in a sensor housing for protection against external influences. This housing encloses the stator elements and is mounted axially. The sensor element is then inserted radially through a recess in the sensor housing, so that it extends radially from the outside into the axial space between the collecting sections. Accordingly, assembly is relatively complex. In addition, suitable sealing agents must be used to ensure that the sensor element's passage through the sensor housing is sealed to the outside. This increases the structural complexity.

[0010] In view of the problems explained above, it is an object of the present invention to enable simpler assembly and to reduce the construction effort.

[0011] Description of the invention

[0012] This object is achieved according to the invention by the rotation sensor having the features of claim 1 and the steering system according to claim 9. Advantageous further developments emerge from the subclaims.

[0013] In a rotation sensor for a steering system of a motor vehicle, comprising a magnetic element rotatable about a sensor axis and a stator stationary relative to the sensor axis with coaxially arranged stator elements which have two axially spaced collecting sections between which a sensor element is arranged, wherein the stator and the sensor element are arranged in a sensor housing, the invention provides that the sensor element is rotatably mounted relative to the stator about an axis of rotation parallel to the sensor axis and radially spaced from it. According to the invention, the sensor element is rotatable relative to the stator about an axis of rotation eccentric with respect to the sensor axis. By rotating about this axis of rotation, the sensor element can be pivoted from the outside towards the stator elements, wherein it is moved in an arc with a radial movement component with respect to the sensor axis.This radial movement allows the sensor element to be inserted radially from the outside between the axially spaced collecting sections and positioned in the measuring position. Due to the eccentric arrangement of the rotation axis relative to the sensor axis, the sensor element can be easily mounted by positioning it axially at a height between the collecting sections and then rotating it around the rotation axis on an arcuate path directed towards the stator into its final mounting position between the collecting sections. One advantage of this is that the sensor element can be inserted simply by axial positioning and subsequent rotation around the rotation axis. This reduces the assembly effort, and sealing the sensor element can be achieved with less effort.

[0014] An advantageous development is that the sensor element is attached to the sensor housing, and the sensor housing can be rotated about the axis of rotation relative to the stator. By rotating the housing about the axis of rotation, the radial distance between the stator elements arranged coaxially to the sensor axis and the sensor element attached to the housing eccentrically to the sensor axis can be adjusted. By simply rotating the housing, the sensor element can be inserted radially between the collecting sections. The sensor element can be fixed in the sensor housing, and the connecting cables can be led out of the sensor housing in a sealed manner, preferably in the axial direction. It is advantageous that the sensor element can be designed to be integrated and sealed with the sensor housing and can be brought into operative engagement with the stator simply by axial joining and subsequent rotation of the sensor housing.This eliminates the complex connections and seals between the sensor housing and the radially inserted sensor element, which are common in the prior art. Accordingly, manufacturing costs can be reduced.

[0015] It is advantageous for the sensor housing to have a circular outer circumference. The sensor housing can be substantially cylindrical, with a circular cross-section coaxial with the rotational axis. This allows the sensor housing as a whole to be mounted on its outer circumference for rotation about the rotational axis, which can be referred to as the housing axis. For example, the sensor housing can be mounted so that it can rotate about the rotational axis relative to a steering housing.

[0016] It can be provided that at least one collecting section projects radially outward from a stator element over a partial circumferential area with respect to the sensor axis. The collecting sections can preferably comprise circular disks, also referred to as stator laminations. These project radially outward with respect to the sensor axis, and the sensor element is arranged between their opposing axial sides. It is also possible for the collecting sections to be circular and project radially outward over their entire circumference.

[0017] It is possible for the sensor housing to be pot-shaped. This design has an axial wall, which can also be referred to as the pot base, a connected, circumferential outer wall, and an axial opening. The sensor element can be fixed internally to the pot base and / or the outer wall. Preferably, the electrical connections of the sensor element can be led axially through the pot base to the outside of the sensor housing. The sensor housing can be mounted axially on a steering housing through the axial opening until the sensor element is positioned axially at the level of the stator. The sensor housing can then be pivoted as a whole about the eccentric axis of rotation, whereby the sensor element is inserted between the collecting sections.

[0018] The sensor housing may be provided with a mounting flange. The mounting flange may preferably extend annularly around an axial opening, for example, in the case of a tubular or pot-shaped sensor housing. It may have fastening means for connection to a steering housing, for example, flange bores. These can preferably be designed and arranged such that the sensor housing can be joined in the axial direction relative to the stator, and the fastening means can be connected to one another after the sensor housing has rotated about the axis of rotation.

[0019] A preferred embodiment can be realized in that the sensor element can be moved past at least one stator element in the axial direction for assembly in a first angular position, and is radially covered by the two collecting sections in a second angular position rotated relative to the axis of rotation. For assembly, the sensor element can be oriented in a first angular position, the so-called assembly position, relative to the axis of rotation in a first assembly step. In this assembly position, it is moved axially towards the stator elements until it has moved axially past one of the stator elements and is axially positioned at the level of the distance between the collecting sections. The sensor element is thus inserted axially. It is initially arranged radially outside the collecting sections.In a subsequent second assembly step, the sensor element is pivoted in a radial direction into a second angular position towards the stator elements by rotating around the axis of rotation eccentric with respect to the sensor axis, until it is immersed in the axial space between the collecting sections and is radially covered by the two collecting sections.

[0020] It is particularly advantageous that the sensor element is fixed to the sensor housing prior to assembly. This allows the sensor housing and the sensor element to be mounted together using the aforementioned sequence of axial and rotational movements.

[0021] Preferably, the sensor element can be provided with an axially insertable electrical plug connection. The plug connection can, for example, comprise a socket or the like, which can preferably be attached to the sensor housing. It can preferably be arranged on an axial side. This simplifies axial assembly.

[0022] It is possible for the stator elements to be rotatable relative to the sensor housing about the sensor axis. To implement a torque sensor, the stator elements can be attached to a first steering shaft part, and the magnetic element to a second steering shaft part that is rotatable relative thereto. The first steering shaft part is connected to the second steering shaft part via a torsion bar, so that the relative rotation of the steering shaft parts measured by the rotation sensor correlates with the torque transmitted via the steering shaft, the steering torque. The rotation of the stator relative to the sensor housing indicates the absolute rotational position of the steering shaft and can be detected using a suitable sensor, for example a conventional rotational position sensor.

[0023] In a steering system for a motor vehicle with a steering shaft rotatable about a sensor axis in a steering housing and a rotation sensor, comprising a magnetic element attached to the steering shaft and a stator fixed relative to the sensor axis with coaxially arranged stator elements that have two axially spaced collecting sections, between which a sensor element is arranged, wherein the stator elements and the sensor element are arranged in a sensor housing, the invention provides that the sensor element is rotatably mounted relative to the stator about an axis of rotation parallel to and radially spaced from the sensor axis. According to the invention, the rotation sensor is designed according to one of the inventive embodiments described above.

[0024] The steering housing can, for example, be a steering column housing in which a steering shaft designed as a steering spindle is mounted. The sensor housing is attached to the steering housing.

[0025] Preferably, the sensor element is mounted on the sensor housing, which is rotatable relative to the stator about the rotational axis. The sensor element is mounted eccentrically, i.e., at a radial distance from the sensor axis, on the sensor housing.

[0026] An advantageous embodiment can provide for the sensor housing to be rotatable relative to the steering housing about the rotational axis. The sensor axis, which is formed by the axis of the steering shaft, is fixed relative to the steering housing. Because the sensor housing is rotatable relative to the steering housing about the eccentric rotational axis, which is also referred to as the housing axis, the sensor element can be positioned radially relative to the stator elements by rotating the sensor housing, as described above.

[0027] Preferably, the sensor housing can be fixed to the steering housing with respect to rotation about the rotation axis. This makes it possible to fix the operative connection between the sensor element and the stator, in which the sensor element is inserted between the collecting sections, during operation.

[0028] It is preferred that the sensor housing be axially connected to the steering housing. For example, an axial flange connection can be implemented.

[0029] Description of the drawings

[0030] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. In detail:

[0031] Fig. 1 shows a motor vehicle steering system in a schematic perspective view,

[0032] Fig. 2 is a schematic perspective view of a rotation sensor of the steering system according to Fig. 1, Fig. 3 is an axial partial view of the rotation sensor according to Fig. 2,

[0033] Fig. 4 is a partial perspective view of the rotation sensor according to Fig. 2.

[0034] Embodiments of the invention

[0035] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

[0036] Fig. 1 schematically illustrates a motor vehicle steering system 1 designed as an electromechanical power steering system. This system comprises a steering column 2 with a support unit 21 that can be attached to a motor vehicle body (not shown).

[0037] The steering column 2 has a steering housing 22 in which a steering shaft with a first, upper steering shaft part 10 is mounted rotatably about a longitudinal axis L. At the rear end with respect to the direction of travel, a steering wheel 12 is mounted on the steering shaft part 10 in a rotationally fixed manner, via which a driver can transmit a steering torque (manual torque) as a steering command to the upper steering shaft part

[0038] 10 can bring in.

[0039] The upper steering shaft part 10 is connected to a second, lower steering shaft part 11 of the steering shaft via a torsionally elastic torsion bar (not shown here).

[0040] The steering torque is transmitted via the steering shaft parts 10 and 11 via intermediate universal joints 13 to a steering pinion 14, which engages a longitudinally displaceable rack 15. This converts a rotation of the steering shaft during a steering intervention into a displacement of tie rods 16, as indicated by the double arrow, which transmit the specified steering intervention as a steering angle to the steerable wheels 17 of the motor vehicle.

[0041] An electric auxiliary power assistance can be an auxiliary power drive 3 attached to the steering column 2 and coupled to the steering shaft 10, or an auxiliary power drive 3 attached to the pinion 14 with the steering shaft part

[0042] 11, wherein the auxiliary power drives 3 and 31 can be constructed similarly. The auxiliary power drive 3 or 31 can couple an auxiliary torque into the lower steering shaft 11 and / or the steering pinion 14 to assist the driver in steering. An auxiliary power drive 32 can also be provided to introduce an auxiliary power to the rack 15 that supports the steering.

[0043] Typically, an auxiliary drive 3, 31, or 32 is mounted at only one of the three positions shown. The auxiliary torque or auxiliary force to be applied to assist the driver by means of the respective auxiliary drive 3, 31, or 32 is determined taking into account a steering torque manually applied by the driver.

[0044] The steering column 2 has a rotation sensor 4, which is connected to the steering housing 22 and has a torque sensor that detects the relative rotation of the steering shaft parts 10 and 11, which depends on the magnitude of the manually applied steering torque. Furthermore, the rotation sensor 4 can provide a rotation angle sensor for detecting the rotational position, i.e., the angular position of the steering shaft parts 10 and 11 relative to the steering housing 22. Depending on the measured values ​​of the rotation sensor 4, the auxiliary drives 3, 31, or 32 can be controlled.

[0045] Instead of the auxiliary drives 3, 31 or 32, in a steer-by-wire steering system which does not have a continuous mechanical connection between the steering wheel 12 and the steerable wheels 17, electric steering actuators can be controlled depending on the measured values ​​of the rotation sensor 4 to generate a steering angle of the wheels 17 by means of an electric motor.

[0046] The rotation sensor 4 is arranged between the upper steering shaft part 10 and the lower steering shaft part 11, as can be seen in the enlarged illustration of Fig. 2, which shows a schematically cut-out perspective view.

[0047] The rotation sensor 4 has a pot-shaped sensor housing 41 which is connected to the steering housing 22, as indicated in Fig.2.

[0048] Fig.3 shows an axial view in the direction of the longitudinal axis L into the opened sensor housing 41, and Fig.4 a view oblique to the longitudinal axis L.

[0049] The rotation sensor 4 has a stator 5, which has two stator elements 51, 52 coaxial with the longitudinal axis L, which are arranged coaxially with the steering shaft parts 10 and 11, as can be seen in Fig. 3. The stator elements 51, 52 have two axially spaced, circular disk-shaped collecting sections 53, 54. In the illustrated installation position, a sensor element 6 is inserted radially from the outside into the axial space between the collecting sections 53, 54.

[0050] A magnetic element 56 is attached to one of the steering shaft parts 10 or 11, as schematically indicated in Fig. 3. The stator 5 is mounted on the other steering shaft part 11 or 10 in a rotationally fixed manner. The steering shaft parts 10 and 11 are connected to one another via a torsionally elastic torsion bar (not shown here), so that a torque introduced into the steering shaft causes the magnetic element 56 to rotate relative to the stator 5. A resulting spatial change in the magnetic flux between the collecting sections 53 and 54 is detected by the sensor element 6 and output as an electrical measured value.

[0051] The longitudinal axis L corresponds to the sensor axis in the sense of the invention.

[0052] A measurement of the rotational position of the steering shaft 10, 11 can be carried out by means of further measuring means 7, which are coupled, for example, via gears or the like and are designed to be able to detect a rotation of the stator 5 relative to the steering housing 22.

[0053] The sensor element 6 is rotatable relative to the stator 5 about a rotational axis D, which is arranged parallel and spaced from the longitudinal axis L. For example, the sensor element 6 can be attached to the sensor housing 41, which is rotatable about the rotational axis D relative to the steering housing 22. As in the example shown, the sensor housing 41 can be cylindrical, with the rotational axis D arranged centrally.

[0054] For assembly, the sensor housing 41 can be oriented relative to the steering housing 22 such that the sensor element is in position P shown in Fig. 3. In this orientation, the sensor housing 41 can be joined to the steering housing 22 in the axial direction, wherein the sensor element 6 can be moved axially past the stator 5 until it is positioned at an axial height between the collecting sections 53 and 54. The sensor housing 41 can then be pivoted about the axis of rotation D, wherein the sensor element 6 is moved towards the stator 5 on an arcuate path B with a radial movement component, as schematically indicated in Fig. 3 by the dashed arrow. As a result, the sensor element 6 can be inserted into its final assembly position between the collecting sections 53 and 54, as shown in Figs. 3 and 4. The sensor housing 4 can be fixed to the steering housing 22 by means of a circumferential fastening flange 42.

[0055] List of reference symbols

[0056] 1 steering system

[0057] 10 Steering shaft part

[0058] 11 Steering shaft part

[0059] 12 Steering wheel

[0060] 13 universal joint

[0061] 14 pinions

[0062] 15 Rack

[0063] 16 Tie rod

[0064] 17 wheels

[0065] 2 steering column

[0066] 21 Support unit

[0067] 22 Steering housing

[0068] 3.31 , 32 auxiliary drive

[0069] 4 rotation sensor

[0070] 41 Sensor housing

[0071] 42 Mounting flange

[0072] 5 Stator

[0073] 51, 52 Stator elements

[0074] 53, 54 collection sections

[0075] 56 Magnetic element

[0076] 6 Sensor element

[0077] 7 Measuring instruments

[0078] L Longitudinal axis

[0079] D axis of rotation

[0080] B Bahn

[0081] P Position

Claims

PATENT CLAIMS 1. Rotation sensor (4) for a steering system (1) of a motor vehicle, comprising a magnetic element (56) rotatable about a sensor axis (L) and a stator (5) fixed relative to the sensor axis (L) with coaxially arranged stator elements (51, 52) which have two axially spaced collecting sections (53, 54) between which a sensor element (6) is arranged, wherein the stator (5) and the sensor element (6) are arranged in a sensor housing (41), characterized in that the sensor element (6) is mounted rotatably relative to the stator (5) about an axis of rotation (D) parallel to and radially spaced from the sensor axis (L).

2. Rotary sensor according to claim 1, characterized in that the sensor element (6) is attached to the sensor housing (41), which is rotatable relative to the stator (5) about the axis of rotation (D).

3. Rotary sensor according to one of the preceding claims, characterized in that the sensor housing (41) has a circular outer circumference.

4. Rotary sensor according to one of the preceding claims, characterized in that at least one collecting section (53, 54) projects radially outwards from a stator element (51, 52) over a circumferential partial area with respect to the sensor axis (L).

5. Rotation sensor according to one of the preceding claims, characterized in that the sensor housing (41) is pot-shaped.

6. Rotation sensor according to one of the preceding claims, characterized in that the sensor housing (41) has a fastening flange (42).

7. Rotary sensor according to one of the preceding claims, characterized in that the sensor element (6) is movable past at least one stator element (51, 52) in the axial direction for mounting in a first angular position, and is radially covered by the two collecting sections (53, 54) in a second angular position rotated relatively about the axis of rotation (D).

8. Rotary sensor according to one of the preceding claims, characterized in that the stator elements (51, 53) are rotatable relative to the sensor housing (41) about the sensor axis (L).

9. Steering system (1) for a motor vehicle with a steering shaft (10, 11) rotatable about a sensor axis (L) in a steering housing (22) and with a rotation sensor (4), comprising a magnetic element (56) attached to the steering shaft (10, 11) and a stator (5) fixed relative to the sensor axis (L) with coaxially arranged stator elements (51, 52) which have two axially spaced collecting sections (53, 54) between which a sensor element (6) is arranged, wherein the stator (5) and the sensor element (6) are arranged in a sensor housing (41), characterized in that the sensor element (6) is mounted rotatably relative to the stator (5) about an axis of rotation (D) parallel to and radially spaced from the sensor axis (L).

10. Steering system according to claim 9, characterized in that the sensor element (6) is attached to the sensor housing (41), which is rotatable relative to the stator (5) about the axis of rotation (D).

11. Steering system according to one of claims 9 or 10, characterized in that the sensor housing (41) can be positioned so as to be rotatable about the axis of rotation (D) relative to the steering housing (22).

12. Steering system according to claim 11, characterized in that the sensor housing (41) can be joined axially to the steering housing (22).

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