Steering system for a motor vehicle

Abstract

The present invention relates to a steering column (1) for a motor vehicle, comprising two components (3, 4) which can be shifted relative to one another and a position detection device (7) which has a sensor unit (71) connected to one component (3), which sensor unit is movable, in a shifting direction, relative to a target unit (72) connected to the other component (4), and is designed to detect the relative position of the target unit (71), wherein the target unit (71) has a target element (73) which extends in a planar manner in parallel with the shifting direction (x) and which has a measurement variable that can be detected by the sensor unit (71) and that varies along the shifting direction. In order to make improved position detection possible, according to the invention the target unit (72) has a plastics layer (75) connected to the target element (73).

Description

[0001] Steering system for a motor vehicle

[0002] State of the art

[0003] The invention relates to a steering column for a motor vehicle, which has two components which can be adjusted relative to one another and a position detection device which has a sensor unit which is connected to one component and which is movable along an adjustment direction relative to a target unit which is connected to the other component and which is designed to detect the relative position of the target unit, wherein the target unit has a target element which extends flatly parallel to the adjustment direction and which has a measurement variable which can be detected by the sensor unit and which varies along the adjustment direction.

[0004] Such a steering column has a manual steering handle for inputting steering commands at its rear end, facing the driver's position, relative to the direction of travel of the vehicle. For example, a steering wheel rotatable about a longitudinal axis in an actuating unit. At a distance from this steering-wheel-side end, the steering column is attached to the vehicle body in a body-side area, usually via a support unit.

[0005] To easily adapt the steering wheel position to the driver's position, the steering handle is adjustable relative to the vehicle body. For longitudinal adjustment, adjustment can be made in the longitudinal direction defined by the longitudinal axis, and for optional height adjustment, transverse to this in a vertical direction. To achieve longitudinal adjustment, an actuating unit carrying the steering handle can be telescopically accommodated in a casing unit, which can also be referred to as a guide box or box swing arm. Height adjustment can be achieved by pivoting the casing unit around a horizontal axis in a front area of ​​the support unit, allowing the steering handle to be pivoted vertically.

[0006] For optimal activation of steering column-related safety systems, for the automated adjustment of an individual steering wheel position, or to adjust the steering column during autonomous driving of an autonomously driving vehicle from the operating position to a remote storage position outside the operating range, it is necessary to detect the current adjustment position in the respective adjustment direction. For this purpose, a steering column with an electronic position detection device is known in the prior art, for example from EP 4 032 783 A2 or DE 10 2020 115162 A1. The device comprises a sensor and a cooperating sensor target for detecting the position of components that can be moved relative to one another, for example, the actuating unit relative to the casing unit or the casing unit relative to the support unit.

[0007] For this purpose, a sensor unit is provided that is connected to one component, for example, the actuating unit, the casing unit, or the support unit, and can detect the relative linear position of a target unit that is fixed to the other component that is adjustable relative to the one component, for example, the casing unit or the support unit. When the steering column is adjusted, the sensor unit is moved along the target unit in the adjustment direction.

[0008] The target unit comprises a target element whose length extends in the adjustment direction and is formed from a target material that can be detected contactlessly by the sensor unit, for example, an inductively detectable metallic material. Because the target element has a measurand that varies along the adjustment direction, for example, an increasing width or thickness perpendicular to the adjustment direction, the relative position in the adjustment direction can be determined from the measurement signal of the sensor device.

[0009] To ensure sufficient linearity and measurement accuracy of the position detection, the sensor unit must be guided along the target element while maintaining a constant measuring distance perpendicular to the target plane. In the current state of the art, the measuring distance is determined by the width of the air gap between the sensor unit and the target element freely positioned opposite it. External influences during operation can compromise the maintenance of a constant measuring distance over the entire adjustment range, which can negatively impact the linearity of the measurement.

[0010] In view of the problems explained above, it is an object of the present invention to enable improved position detection.

[0011] Description of the invention

[0012] This object is achieved according to the invention by the steering system having the features of claim 1. Advantageous further developments emerge from the subclaims. In a steering column for a motor vehicle, which has two components which can be adjusted relative to one another and a position detection device which has a sensor unit connected to one component, which is movable relative to a target unit connected to the other component along an adjustment direction and which is designed to detect the relative position of the target unit, wherein the target unit has a target element which extends flatly parallel to the adjustment direction and which has a measured variable which can be detected by the sensor unit and which varies along the adjustment direction, it is provided according to the invention that the target unit has a plastic layer connected to the target element.

[0013] According to the invention, the target unit is designed as a composite component with a layer structure which extends flatly parallel to an xy plane, which is referred to as the target plane. By definition, the adjustment direction is parallel to the x-axis. The target element lies in a layer of the target unit which is parallel to the target plane and, by definition, has a length in the x-direction and a width in the y-direction. It is preferably at least partially covered by the plastic layer according to the invention, which is arranged in the direction of the normal to the target plane on at least one side of the target element. During adjustment, the sensor unit can preferably move linearly in the adjustment direction, i.e. the x-direction, relative to the target element on a straight or at least partially curved adjustment path.

[0014] The measured value varying in the x-direction, for example a width in the y-direction that is clearly assigned to an x-position, enables reliable absolute position determination.

[0015] The plastic material of the plastic layer is essentially transparent with respect to the non-contact measurement method used, meaning that the quantity and dimensions of the plastic material arranged near the sensor unit on the target element do not affect the measurement, or at least do not significantly affect it. For example, in a preferred inductive measurement method, in which the inductance of a measuring coil of the sensor unit is changed depending on the position by a metallic target element, the magnetic field relevant for the measurement may not be affected, or not significantly affected, by the plastic material.

[0016] The plastic layer is firmly bonded to the target element. This makes it possible to maintain the shape and dimensions of the target element, which are crucial for position determination, unchanged, while allowing the plastic layer to be freely designed in terms of its shape, dimensions, and arrangement. This expands the possibilities for the spatial arrangement of the target element relative to the sensor unit. Furthermore, the interaction of the plastic layer with the sensor unit can advantageously create a type of mechanical guide, which enables the measuring distance between the sensor unit and the target element to be kept constant within narrow tolerances over the entire adjustment range. This results in the advantage of greater linearity of the measurement result.

[0017] To achieve a constant measuring distance, it is advantageous for the plastic layer to be arranged between the target element and the sensor unit. The plastic layer forms a flat cover layer of the target unit, facing the outside of the sensor unit, which preferably covers the target element over the entire adjustment path, i.e. projects beyond the target element in the x and y directions. For example, the plastic layer can be essentially as long as the target unit, and the target element can extend therein over a portion of the length which corresponds to the adjustment path. The width of the plastic layer can be constant over the entire length, in contrast to a width of the target element varying over the length in the y direction.The advantage of this arrangement is that the plastic layer, due to its given thickness, measured perpendicular to the target plane, essentially forms a spacer between the sensor unit and the target element, extending the length of the target element, i.e., over the entire adjustment range. This makes it possible to achieve a constant measuring distance simply by guiding the sensor unit along the outer side of the plastic layer, facing away from the target element.

[0018] It is advantageous for the plastic layer to have a consistent width perpendicular to the adjustment direction over the entire adjustment range over which the sensor unit can be moved relative to it. This allows a uniform external shape of the target unit to be specified regardless of the varying width of the target element, simplifying alignment and maintaining a constant measuring distance.

[0019] It can be provided that the target element is embedded in the plastic layer. The target element can be at least partially enclosed by the plastic, preferably on all sides by the plastic of the plastic layer, so that it is at least partially covered by a plastic cover layer on its side facing the sensor unit, and optionally also on the side facing away. It is permanently and permanently connected to the plastic and housed in a manner protected against corrosion and other external influences. It is preferably possible for the plastic layer to comprise a thermoplastic polymer or an epoxy resin.

[0020] This means that it can be efficiently manufactured using plastic injection molding and can be molded onto the target element for a material-to-material connection, or the target element can be completely or partially molded over with the plastic.

[0021] In an advantageous development, the plastic layer can be glass fiber reinforced. For example, glass fibers are embedded in the plastic layer. This can be achieved, for example, using a glass fiber mat. In particular, a combination of an epoxy resin with embedded glass fibers has proven very advantageous for forming an epoxy resin-glass fabric composite.

[0022] The target element preferably comprises a metal. For inductive measurement, the target element can be made of a metallic material, for example, copper or iron, or of a composite material comprising a metal, for example, a plastic with a metallic additive.

[0023] It is advantageous for the plastic layer to be flat. The plastic layer can preferably have a flat, smooth surface on the outer side, which extends parallel to the target plane and faces the sensor unit. In this way, the constant thickness of the plastic layer, measured in the normal direction of the target plane, can be used to specify a constant measuring distance to the measuring unit.

[0024] In the aforementioned embodiment, it can be provided that the sensor unit is slidably mounted on the plastic layer. The sensor unit can slide along the plastic layer in the adjustment direction during a relative adjustment along the adjustment path. As a result, the measuring distance perpendicular to the plane of the target unit between the sensor unit and the target element can be defined by the constant thickness of the plastic layer between the target element and the sensor unit. The advantage is that the measurement is precise and easily reproducible due to the measuring distance being constant over the entire adjustment path. It can also be advantageous for the plastic layer and the sensor unit to be in sliding contact via a material pairing with good sliding properties and low sliding friction.

[0025] In a further development of the aforementioned embodiment, the sensor unit can be spring-loaded against the target unit. This allows the sensor unit to be elastically pressed against the target unit and held in sliding contact with the plastic layer. This prevents relative movements perpendicular to the surface of the target element, allowing the measuring distance defined by the thickness of the plastic layer to be kept constant.

[0026] It can be provided that the target element has a plate-shaped carrier element, for example in the form of a carrier plate. The carrier element is made of a material that is not or not significantly detectable for the measuring method used, for example a plastic. The actual, detectable target element can be attached to this. This can be designed as a thin target layer, for example from a metallic material such as copper or the like. The carrier element is designed to be flat and parallel to the target unit and made of a material that is permeable to the measuring method used, for example a plastic. The target layer can be arranged on one or both sides of the carrier element, for example in the form of a metallic layer. According to the invention, a plastic layer can be permanently attached to the carrier element, at least on the side on which the target element is arranged.In this way, a multilayer structure is formed from the carrier element, the target element, and the plastic layer. It can further be provided that the carrier element is also covered with a plastic layer on its side facing away from the target element. In particular, it is possible for the carrier element to be substantially completely embedded in the plastic.

[0027] It is expedient for the sensor unit to be designed to perform an inductive or capacitive measuring method. To implement an inductive measuring method, the sensor unit can have an excitation coil or a permanent magnet for generating a measuring magnetic field, within which the metallic material can be moved in the adjustment direction. Using an electronic magnetic field sensor, for example, a Hall or GMR sensor, a measurement signal dependent on the relative position of the target element can be recorded and evaluated for position determination.

[0028] Preferably, the target element may have a consistently uniform thickness normal to the target plane, for example in the form of a target layer made of a metallic material.

[0029] The target element can be designed to be wedge-shaped and taper in the adjustment direction. It can also have a triangular or trapezoidal shape that tapers in sections in the x-direction of the adjustment, with a width that decreases continuously, for example, linearly, along the y-direction. The width, which is clearly assigned to an x-position, allows for reliable absolute position determination.

[0030] Alternatively, it may be advantageous for the target element to be wave-shaped and rounded in the adjustment direction. For example, it may have a substantially sinusoidal shape, with the surface sections enclosed by the sine curve and the zero line, which preferably runs in the x-direction, comprising the target material.

[0031] An advantageous development can provide for at least two target elements to be arranged next to one another transversely to the adjustment direction. The target elements can run parallel to one another in the x-direction. They can preferably be of equal length and each extend over the entire length of the adjustment path. Each of the target elements can be detected and measured by an associated sensor element of the sensor unit, so that, in principle, an independent position measurement can be realized. This can provide advantageous redundancy in position detection to increase the reliability of position determination and the safety level.

[0032] It can be advantageous for at least two target elements to have a different width profile along their length in the adjustment direction. The target elements arranged parallel to one another in width can, for example, be arranged antiparallel in a wedge shape. An advantageous embodiment is for two wave-shaped target elements to be arranged offset in the x-direction, for example, each with a sinusoidal profile with a different phase in the x-direction.

[0033] Description of the drawings

[0034] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. In detail:

[0035] Figure 1 shows a steering column according to the invention in a schematic perspective view,

[0036] Figure 2 shows the steering column according to Figure 1 in a further perspective view,

[0037] Figure 3 shows a longitudinal section through a target unit according to the invention, Figure 4 shows a schematic plan view normal to the target plane of a target element according to the invention in a first embodiment,

[0038] Figure 5 is a view as in Figure 4 of a target element according to the invention in a second embodiment,

[0039] Figure 6 is a view as in Figure 4 of a target element according to the invention in a third embodiment.

[0040] Embodiments of the invention

[0041] In the various figures, identical parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

[0042] Fig. 1 shows a steering column 1 according to the invention as part of a steering system of a motor vehicle not shown here.

[0043] The steering column 1 comprises a casing unit 2 in which a steering spindle 3 is mounted rotatably about a longitudinal axis L. At the rear end section, facing the driver's position with respect to the direction of travel, a steering wheel 32 is attached to a fastening section 31.

[0044] The steering column 1 can be designed as a conventional steering column, as shown in Figure 1, in which the steering spindle 3 is mechanically coupled to the steerable wheels via intermediate shafts 33. Alternatively, the steering column 1 can be designed as a steer-by-wire steering column, in which the steering spindle 3 is not mechanically connected to the wheels to be steered and only protrudes at the rear, on the driver's side, for mounting the steering wheel 32. The intermediate shafts 33 are not present in this case.

[0045] The casing unit 2 is held in a support unit 4 that can be attached to the body of the vehicle. For this purpose, the support unit 4 can have fastening means 41, for example, fastening holes or the like.

[0046] The steering wheel 32 is adjustable relative to the support unit 4, which is fixed to the body when installed, in the longitudinal direction defined by the longitudinal axis L, as indicated by the double arrow. For height adjustment, the steering wheel 32 is adjustable up or down in a height direction H relative to the support unit 4 transversely to the longitudinal axis L, as also indicated by a double arrow.

[0047] The longitudinal axis L defines a first adjustment direction, and the height direction H a second adjustment direction, which are collectively referred to as the two adjustment directions.

[0048] Figure 2 shows the steering column 1 enlarged in a sideways tilted perspective view.

[0049] The steering spindle 3 is mounted in an inner casing 21 for rotation about the longitudinal axis L. For longitudinal adjustment, this inner casing 21 is telescopically received in an outer casing 22 of the casing unit 2 in the direction of the longitudinal axis L.

[0050] For height adjustment, the support unit 4, specifically the outer shell 22, is pivotally mounted in a region close to the body, at the front with respect to the direction of travel, about a pivot axis 42 lying horizontally, transversely to the longitudinal axis L. By pivoting about this pivot axis 42, the steering wheel 32 attached to the driver-side rear end of the steering spindle 3, remote from the body, can be adjusted in the height direction H.

[0051] For the motorized longitudinal adjustment, a first adjustment drive 5 is provided, which can be designed, for example, in a manner known per se as a spindle drive and is operatively inserted between the inner casing 21 and the outer casing 22.

[0052] For motorized height adjustment, a second adjustment drive 6 is provided, which can also be designed, for example, in a manner known per se as a spindle drive and is operatively inserted between the casing unit 2 and the support unit 4.

[0053] A position detection device 7 according to the invention comprises a sensor unit 71 fixed to the casing unit 2, which is shown schematically, and a target unit 72 connected to the inner casing 21. This is adjustable relative to the sensor unit 71 in the direction of the longitudinal axis L.

[0054] The target unit 72 is flat and parallel to a yx target plane. It has a length in the x-direction that corresponds to the adjustment direction. Its width is specified perpendicular to this in the y-direction, which in the example shown in Figure 2 corresponds to the height direction H. Figure 3 shows a schematic longitudinal section through the position detection device 7 with the sensor unit 71 and a target unit 72 according to the invention, which is displaceable in the longitudinal direction L, corresponding to the x-direction, relative to the sensor unit 71 during adjustment.

[0055] In Fig.3, the y-direction points vertically out of the drawing plane towards the observer.

[0056] A target element 73 is formed as a metallic layer or plate-shaped and extends flatly in the xy target plane. It is made of a metallic material, for example, copper.

[0057] The target element 73 can be mounted on a support element 74, which is designed as a support plate parallel to the xy target plane. The support element 74 consists of a support material that does not impair the measurement of the target element 73 by the sensor unit 71. In an inductive measurement method, this can be, for example, glass, a plastic, or the like.

[0058] A plastic layer 75 according to the invention is applied to the upper side of the target element 73 in Fig.3, for example by overmolding with a thermoplastic polymer.

[0059] The plastic layer 75 facing the sensor unit 71 preferably has a constant thickness D over the entire adjustment path, which corresponds to the measuring distance between the sensor unit 71 and the target element 73.

[0060] The sensor unit 71 can slide along the flat, smooth surface of the plastic layer 75 in the longitudinal direction L in sliding contact, as indicated in Fig.3 by the double arrow.

[0061] The target unit 71 can optionally also have a plastic layer 75 on its side facing away from the sensor unit 71, which is located at the bottom in the illustration of Fig. 3. The plastic layers 75 can preferably be produced by overmolding with a thermoplastic polymer in an injection molding process.

[0062] Deviating from the illustration in Fig.3, it is also possible that no carrier element 74 is present and only one target element 73 is fully or partially embedded in the plastic, wherein preferably a continuous plastic layer 75 is formed at least on the side facing the sensor unit 71.

[0063] Fig.4 shows a schematic plan view - seen from the sensor unit 71 in the direction of the measuring distance - of a triangular target element 73 which converges in a wedge shape in the x-direction. This is mounted on a carrier element 74 in the form of a rectangular carrier plate.

[0064] According to the layered structure shown in Fig.3, the carrier element 74 is preferably covered over its entire xy surface by a flat plastic layer 75, which has a constant thickness D in the region of the target element 73.

[0065] Fig. 5 shows a second embodiment in a representation similar to Fig. 4. This embodiment, with an otherwise identical structure, has two target elements 73 that are wedge-shaped and arranged antiparallel in the x-direction. These are of equal length and each extend over the entire length of the adjustment path in the x-direction, while being arranged side by side in the y-direction. The sensor unit 71 can preferably have two sensor elements correspondingly assigned to the two target elements 73.

[0066] Fig. 6 shows a further embodiment with two target elements 73, which are arranged side by side analogously to the embodiment according to Fig. 5. The target elements 73 are each designed as a sine wave and have a phase position offset from one another in the x-direction.

[0067] For position detection in the height direction H, the steering column 1 can have a further, essentially similarly constructed position detection device 7. The sensor unit 71 and the target unit 72 can be attached to components that are adjustable relative to one another in the height direction, for example, to the casing unit 2 and the support unit 4. List of reference symbols

[0068] 1 steering column

[0069] 2 jacket unit

[0070] 21 inner jacket

[0071] 22 Outer jacket

[0072] 3 steering spindle

[0073] 31 Fastening section

[0074] 32 steering wheel

[0075] 4 carrying unit

[0076] 41 Fasteners

[0077] 42 swivel axis

[0078] 43 side panel

[0079] 5 Adjustment drive

[0080] 6 Adjustment drive

[0081] 7 Position detection device

[0082] 71 Sensor unit

[0083] 72 Target Unit

[0084] 73 Target element

[0085] 74 support element

[0086] 75 plastic layer

[0087] L Longitudinal axis

[0088] H Altitude direction

[0089] D thickness of 75

Claims

PATENT CLAIMS 1. A steering column (1) for a motor vehicle, comprising two components (3, 4) which are adjustable relative to one another and a position detection device (7) which has a sensor unit (71) connected to one component (3), which is movable along an adjustment direction relative to a target unit (72) connected to the other component (4), and which is designed to detect the relative position of the target unit (71), wherein the target unit (71) has a target element (73) which extends flatly parallel to the adjustment direction (x) and which has a measured variable which can be detected by the sensor unit (71) and which varies along the adjustment direction, characterized in that the target unit (72) has a plastic layer (75) connected to the target element (73).

2. Steering column according to claim 1, characterized in that the plastic layer (75) is arranged between the target element (73) and the sensor unit (71).

3. Steering column according to one of the preceding claims, characterized in that the target element (73) is embedded in the plastic layer (75).

4. Steering column according to one of the preceding claims, characterized in that the plastic layer (75) comprises a thermoplastic polymer or an epoxy resin.

5. Steering column according to one of the preceding claims, characterized in that the target element (73) comprises a metal.

6. Steering column according to one of the preceding claims, characterized in that the plastic layer (75) is flat.

7. Steering column according to one of the preceding claims, characterized in that the sensor unit (71) is slidably mounted on the plastic layer (75).

8. Steering column according to one of the preceding claims, characterized in that the sensor unit (71) is spring-loaded against the target unit (72).

9. Steering column according to one of the preceding claims, characterized in that the target element (73) has a plate-shaped support element (74).

10. Steering column according to one of the preceding claims, characterized in that the sensor unit (71) is designed to carry out an inductive or capacitive measuring method.

11. Steering column according to one of the preceding claims, characterized in that the target element (73) is designed to converge in a wedge shape in the adjustment direction (x) 12. Steering column according to one of the preceding claims, characterized in that the target element (73) is rounded in a wave-like manner in the adjustment direction (x).

13. Steering column according to one of the preceding claims, characterized in that at least two target elements (73) are arranged next to one another transversely to the adjustment direction (x).

14. Steering column according to claim 13, characterized in that at least two target elements (73) have a different profile of their width (y) over their length in the adjustment direction (x).

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