SENSOR APPARATUS FOR DETECTING THE ROTATION ANGLE POSITION OF A ROTATABLE SHAFT AND STEERING ARRANGEMENT OF A VEHICLE

Abstract

A sensor apparatus (01) is for determining a rotation angle position of a rotatable shaft (02). The sensor apparatus (01) comprises a main gear wheel (03), which is coaxially coupled to the rotatable shaft (02), and a secondary gear wheel (04), which is arranged so as to be rotatably coupled on the main gear wheel (03). The sensor apparatus (01) furthermore comprises two targets (06, 07), each of which is arranged on a lateral face of the main gear wheel (03) or of the secondary gear wheel (04), and two rotation angle sensors (08, 09), which are arranged in the immediate vicinity of the main gear wheel (03) and the secondary gear wheel (04) on a circuit board (05). The angles of the main gear wheel (03) and of the secondary gear wheel (04) are determined and forwarded as an angular signal to an evaluating unit (10) arranged on the circuit board.

Claims

1. A sensor apparatus for determining a rotation angle position of a rotatable shaft which is rotatable by at least −/+360° starting from a zero position, the sensor apparatus comprising: a main gear wheel configured for being coaxially coupled to the rotatable shaft and on which a first electrically conductive target is arranged; a secondary gear wheel which engages in a gear-like manner in the main gear wheel and on which a second electrically conductive target is arranged; a circuit board, which lies parallel to a main extension plane of the main gear wheel and the secondary gear wheel, is arranged in a non-rotatable manner, has a shaft passage through which the rotatable shaft is rotatably guidable, and which carries at least two rotation angle sensors each of which lies opposite a respective one of the first and second electrically conductive targets; and an evaluating unit configured for receiving angular signals supplied by the at least two rotation angle sensors and determining the rotation angle position of the rotatable shaft therefrom; the first electrically conductive target extending over an angular portion of 180° on a lateral face of the main gear wheel, the second electrically conductive target extending over an angular portion of 180° on a lateral face of the secondary gear wheel, the at least two rotation angle sensors being inductive sensors each supplied with an excitation current, a first excitation current for exciting the rotation angle sensor detecting the first electrically conductive target having a different frequency than a second excitation current for exciting the rotation angle sensor detecting the second electrically conductive target.

2. The sensor apparatus according to claim 1, wherein a number of teeth of the main gear wheel and the secondary gear wheel differs by one tooth so that a determination of the rotation angle position of the rotatable shaft can be performed according to the vernier principle.

3. The sensor apparatus according to claim 1, wherein that the first target has a different radius than the second target.

4. The sensor apparatus according to claim 1, wherein the first electrically conductive target is arranged radially outward on the main gear wheel.

5. The sensor apparatus according to claim 1, wherein the second electrically conductive target is arranged radially inward on the secondary gear wheel.

6. The sensor apparatus according to claim 1, wherein rotation angle sensors are provided as coil arrangements on the circuit board.

7. The sensor apparatus according to claim 6, wherein each of the at least two rotation angle sensors has an excitation coil and two receiver coils connected in opposite directions.

8. The sensor apparatus according to claim 1, wherein the main gear wheel and the secondary gear wheel are made of plastic.

9. The sensor apparatus according to claim 1, wherein the first and second electronically conductive targets are each embedded flush with a surface in a lateral face, opposite the circuit board, of the main gear wheel or the secondary gear wheel.

10. A steering arrangement of a vehicle comprising: a rotatable shaft; and the sensor apparatus according to claim 1 arranged on the rotatable shaft.

11. A method of constructing a sensor apparatus for determining a rotation angle position of a rotatable shaft which is rotatable by at least −/+360° starting from a zero position, the method comprising: arranging a first electrically conductive target on a main gear wheel configured for being coaxially coupled to the rotatable shaft; arranging a second electrically conductive target on a secondary gear wheel which engages in a gear-like manner in the main gear wheel; non-rotatably providing a circuit board parallel to a main extension plane of the main gear wheel and the secondary gear wheel such that a first rotation angle sensor on the circuit board is opposite the first electrically conductive target and a second rotation angle sensor on the circuit board is opposite the second electrically conductive target; and providing an evaluating unit configured for receiving angular signals supplied by the first and second rotation angle sensors and determining the rotation angle position of the rotatable shaft therefrom, the first and second rotation angle sensors being inductive sensors, the first rotation angle sensor configured for being operated with a first excitation current for exciting the first rotation angle sensor, the second rotation angle sensor configured for being operated with a second excitation current for exciting the second rotation angle sensor, the first excitation current being different from the second excitation current.

12. A sensor apparatus for determining a rotation angle position of a rotatable shaft which is rotatable by at least −/+360° starting from a zero position, the sensor apparatus comprising: a main gear wheel configured for being coaxially coupled to the rotatable shaft, the main gear wheel supporting a first electrically conductive target; a secondary gear wheel engaging the main gear wheel, the secondary gear wheel supporting a second electrically conductive target; a circuit board arranged in a non-rotatable manner parallel to a main extension plane of the main gear wheel and the secondary gear wheel, the circuit board supporting a first rotation angle sensor opposite the first electrically conductive target and a second rotation angle sensor opposite the second electrically conductive target; and an evaluating unit configured for receiving angular signals supplied by the first and second rotation angle sensors and determining the rotation angle position of the rotatable shaft therefrom, the first and second rotation angle sensors being inductive sensors, the first rotation angle sensor configured for being operated with a first excitation current for exciting the first rotation angle sensor, the second rotation angle sensor configured for being operated with a second excitation current for exciting the second rotation angle sensor, the first excitation current being different from the second excitation current.

13. The sensor apparatus according to claim 12, wherein the first and second electrically conductive targets are each ring sections.

14. The sensor apparatus according to claim 13, wherein the first electrically conductive target extends over an angular portion of 180° on a lateral face of the main gear wheel, the second electrically conductive target extending over an angular portion of 180° on a lateral face of the secondary gear wheel.

15. The sensor apparatus according to claim 12, wherein the first and second rotation angle sensors each have an excitation coil and two opposing receiver coils connected in opposite directions.

16. The sensor apparatus according to claim 15, wherein for each of the first and second rotation angle sensors, the excitation coil is configured for generating a magnetic field which changes over time and induces voltages in the two opposing receiver coils which cancel each other out if there is no electrically conductive object in an effective range of the excitation coil.

17. The sensor apparatus according to claim 16, wherein for each of the first and second rotation angle sensors, if a respective one of the first and second electrically conductive targets is in the effective range of the excitation coil, eddy currents are induced in the respective first or second electrically conductive target, which generate the magnetic field in an opposite direction to an excitation field causing deviating induction voltages in the two receiver coils in opposite directions, and a voltage ratio of the respective first or second electrically conductive target being usable by the evaluating unit to determine a position of the respective first or second electrically conductive target and an angular position of a respective one of the main or secondary gear wheel.

18. The sensor apparatus according to claim 12, further comprising a first bandpass filter coupled to the first rotation angle sensor configured to extract only a first desired frequency for further signal processing and a second bandpass filter coupled to the second rotation angle sensor configured to extract only a second desired frequency for further signal processing.

19. The sensor apparatus according to claim 12, wherein the sensor apparatus is a purely inductive sensor apparatus for determining the rotation angle position of the rotatable shaft.

Description

BRIEF SUMMARY OF THE DRAWINGS

[0020] Further details, advantages and further embodiments of the present disclosure can be found in the following description, in which the present disclosure is described and explained in more detail with reference to the exemplary embodiment shown in the drawing. In the figures:

[0021] FIG. 1 shows a side view of an exemplary embodiment of a sensor apparatus according to the present disclosure;

[0022] FIG. 2 shows a top view of the sensor apparatus;

[0023] FIG. 3 shows a detailed view of a main gear wheel and a secondary gear wheel of the sensor apparatus.

DETAILED DESCRIPTION

[0024] FIG. 1 shows an exemplary embodiment of a sensor apparatus 01 according to the present disclosure. The sensor apparatus 01 is used to determine the rotation angle position of a rotatable shaft 02, which can be part of an electro-mechanical steering system and is in particular a steering shaft. When the sensor apparatus is installed, a main gear wheel 03 of the sensor apparatus is arranged on this steering shaft 02 in the form of a toothed encoder wheel which rotates with the rotatable shaft 02. A rotatably coupled secondary gear wheel 04 in the form of a toothed vernier gear is arranged on this main gear wheel 03, which is caused to rotate by the main gear wheel 03. It is possible to design the main gear wheel 03 with a larger diameter than the secondary gear wheel 04, whereby the secondary gear wheel 04 experiences a higher rotational speed than the main gear wheel 03. Alternatively, the spatial arrangement of the secondary gear wheel 04 on the main gear wheel 03 can differ from the arrangement in FIG. 1. The main gear wheel 03 and the secondary gear wheel 04 have a different number of teeth in order to be able to apply the vernier principle. This also enables the rotation angle to be determined over a rotation range of more than 360°. Furthermore, a first target 06 is arranged on the main gear wheel 03 and a second target 07 on the secondary gear wheel 04 (see FIG. 3), which serve to determine the rotation angle of the gears. Opposite the targets 06, 07, a first rotation angle sensor 08 and a second rotation angle sensor 09 are arranged on a circuit board 05, which detect the movement of the targets and generate an angular signal in each case. An evaluating unit 10, which is also located on the circuit board 05, receives the angular signals and uses them to calculate the absolute rotation angle position of the steering shaft 02. The evaluating unit 10 is preferably a micro-controller which is mounted on the circuit board together with other electronic components.

[0025] The disk-shaped circuit board 05 extends substantially perpendicular to the axis of the steering shaft 02. If necessary, the circuit board 05 can also serve as a rotatable bearing for the steering shaft 02.

[0026] FIG. 2 shows a top view of the sensor apparatus 01. The circuit board 05 has a shaft passage through which the steering shaft 02 is guided. In a manner not shown further, the circuit board 05 is arranged in a non-rotatable manner; this can be realized, for example, by a fastening to the housing or by a bearing on the steering shaft 02. Furthermore, the arrangement of the main gear wheel 03 and the secondary gear wheel 04 is shown.

[0027] FIG. 3 shows the side of the main gear wheel 03 and secondary gear wheel 04 facing the circuit board 05. The target 06 and 07 is arranged on each side respectively, which each cover an annular portion and extend over an angular portion of about 180°. These targets 06, 07 are spaced apart from one another so that mutual interference is reduced. Preferably, the targets 06, 07 are embedded flush with the surface of the main gear wheel 03 or the secondary gear wheel 04.

LIST OF REFERENCE NUMERALS

[0028] 01 Sensor apparatus [0029] 02 Rotatable shaft [0030] 03 Main gear wheel [0031] 04 Secondary gear wheel [0032] 05 Circuit board [0033] 06 First target [0034] 07 Second target [0035] 08 First rotation angle sensor [0036] 09 Second rotation angle sensor [0037] 10 Evaluating unit