SENSOR ASSEMBLY FOR CAPTURING A TORQUE AND AN ANGULAR POSITION OF A ROTATABLE SHAFT

Abstract

The present disclosure relates to a sensor assembly for simultaneously capturing an angular position and a torque of a rotatable shaft. The sensor assembly comprises, for determining the angular position, a main body, two additional bodies, which are arranged coupled for rotation on the main body, and two angle resolvers, which are arranged on a circuit board in the immediate vicinity of the additional bodies. In this arrangement, the angles of the additional bodies are determined by the angle resolvers and passed as an angle signal to an evaluation unit arranged on the circuit board. The sensor assembly further comprises a direct coating, which captures a torque signal from the rotating shaft and passes this signal over a connection line to the evaluation unit. The connection line has a section wound multiple times around the shaft to permit a rotation of the shaft by at least +/−900°.

Claims

1. A sensor assembly for simultaneously determining an angular position and a torque of a rotatable shaft, the sensor assembly comprising: the rotatable shaft configured to be rotatable by at least −/+360° starting from a zero position; a main body coupled to the rotatable shaft; a first body and a second body each of the first body and the second body rotatably coupled to the main body and having a plurality of circumferentially distributed angle marks; a rotationally fixed circuit board; two angle resolvers arranged on the circuit board, each one of the two angle resolvers arranged opposite a corresponding one of the plurality of circumferentially distributed angle marks of the respective first and second bodies, and each of the two angle resolvers configured to supply an angle signal; an evaluation unit arranged on the circuit board the evaluation unit configured to: i) receive the angle signals supplied by the angle resolvers, and ii) determine the angular position of the shaft from the angle signals received from the angle resolvers; and a torque sensor configured as a structured, strain-sensitive direct coating on the rotatable shaft, the strain-sensitive direct coating configured to communicate a torque signal to the evaluation unit via a connected connection line, and the evaluation unit configured to calculate the torque on the rotatable shaft from the torque signal, and the connection line includes a wound section wound multiple times around the shaft, the wound section configured to permit the rotation of the shaft, starting from the zero position, by at least −/+360°.

2. The sensor assembly of claim 1, wherein the main body is a main gear wheel fastened coaxially to the rotatable shaft, and the main gear wheel drivably engages two secondary gear wheels forming the first and second bodies.

3. The sensor assembly of claim 2, characterized in wherein the plurality of circumferentially distributed angle marks are formed by teeth of the secondary gear wheels, and a number of teeth of the two secondary gear wheels differs by one tooth, so that the supplied angle signals can be processed by the evaluation unit according to a Vernier principle.

4. The sensor assembly of claim 1, wherein the circuit board is formed as a disc and includes a shaft passage through which the rotatable shaft is rotatably guided.

5. The sensor assembly of claim 4, wherein the evaluation unit and the two angle resolvers are arranged on a surface of the circuit board facing away from the wound section of the connection line, and the surface is configured as a guide surface for the wound section of the connection line.

6. The sensor assembly of claim 1 wherein the strain-sensitive direct coating is configured as a multilayer system having at least one protective layer and at least one strain-sensitive metal coating.

7. The sensor assembly of claim 1, wherein the angle resolvers are configured as sensors capable of determining angles from at least one of inductively acting sensors or magnetically acting sensors.

8. The sensor assembly of claim 7, wherein a target for an inductively acting sensor is arranged on at least one of the first and second bodies.

9. The sensor assembly of claim 7, wherein a magnet for a magnetically acting sensor is arranged on at least one of the first and second bodies.

10. The sensor assembly of claim 1, wherein the rotatable shaft is a component of a steering system of a vehicle, and the shaft is rotatable by at least −/+900°.

11. The sensor assembly of claim 1, wherein the wound section of the connection line is disposed between the torque sensor and the evaluation unit.

12. A sensor assembly for simultaneously determining an angular position and a torque of a rotatable shaft, the sensor assembly comprising: the rotatable shaft configured to be rotatable by at least −/+360° starting from a zero position; a main body coupled to the rotatable shaft; a first body and a second body, each of the first body and the second body rotatably coupled to the main body and having a plurality of circumferentially distributed angle marks; a rotationally fixed circuit board; two angle resolvers arranged on the circuit board, the two angle resolvers configured to: i) detect the plurality of circumferentially distributed angle marks on the first and second bodies, and ii) supply angle signals; an evaluation unit arranged on the circuit board, the evaluation unit configured to: i) receive the angle signals supplied by the angle resolvers, and ii) determine the angular position of the shaft from the angle signals received from the angle resolvers; and a torque sensor configured as a coating on the rotatable shaft, the coating configured to communicate a torque signal to the evaluation unit via a connection line, and the connection line includes a wound section wound multiple times around the shaft, the wound section configured to permit the rotation of the shaft, starting from the zero position, by at least −/+360′; and the evaluation unit configured to calculate the torque on the rotatable shaft from the torque signal.

13. The sensor assembly of claim 12, wherein at least one of the first or second bodies includes a target for an inductively acting sensor.

14. The sensor assembly of claim 12, wherein at least one of the first or second bodies includes a magnet for interaction with a magnetically acting sensor.

15. The sensor assembly of claim 12, wherein the circuit board is formed as a disc and includes a shaft passage through which the rotatable shaft is rotatably guided.

16. The sensor assembly of claim 12, wherein the coating is configured as a strain-sensitive direct coating.

17. The sensor assembly of claim 16, wherein the strain-sensitive direct coating is configured as a multilayer system having at least one protective layer and at least one strain-sensitive metal coating.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Further details, advantages and further embodiments of the disclosure can be found in the following description, in which the disclosure is described and explained in more detail with reference to the exemplary embodiments shown in the drawing. In the figures:

[0022] FIG. 1 shows a side view of an exemplary embodiment of a sensor assembly according to the disclosure;

[0023] FIG. 2 shows a top view of the sensor assembly according to FIG. 1.

DETAILED DESCRIPTION

[0024] FIG. 1 shows an exemplary embodiment of a sensor assembly 01 according to the present disclosure. The sensor assembly 01 is used for determining an angular position and a torque of a rotatable shaft 02, which can be part of an electromechanical steering system and is in particular a steering shaft. A main body 03 in the form of a gear wheel is arranged on this steering shaft 02 and rotates with the rotatable steering shaft 02. Two additional bodies 04, 05 coupled for rotation in the form of toothed sensor wheels are arranged on this gear wheel 03 and are caused to rotate by the gear wheel 03. It is possible to design the main body 03 to be larger than the additional bodies or sensor wheels 04, 05, as a result of which the additional bodies 04, 05 have a greater rotational speed than the main body 03. Alternatively, the spatial arrangement of the additional bodies 04, 05 on the main body 03 can differ from the arrangement in FIG. 1. Angle marks, which in the simplest case are formed by the teeth, are attached to each of the sensor wheels 04, 05. The sensor wheels 04,05 have a different number of teeth, which differs by one tooth and thus enables application of the vernier principle. Thus, these sensor wheels allow for a more precise angle determination than if an angle detection were only performed on the main body 03. Directly opposite the sensor wheels 04, 05, two angle resolvers 07, 08 are arranged on a circuit board 06, which evaluate the angle marks to determine the angle signals and forward them to an evaluation unit 09 (see FIG. 2). The evaluation unit 09 can be a micro-controller which is attached to the circuit board 06 together with other electronic components.

[0025] The disc-like circuit board 06 is arranged coaxially with the steering shaft 02. If applicable, the circuit board 06 can also be used as a rotatable bearing for the steering shaft 02.

[0026] The sensor assembly further comprises a torque sensor 10 which is formed by a direct coating 11. The direct coating 11 is applied in an axial region on the surface of the steering shaft 02, close to the side of the circuit board 06 on which potentially no components are arranged. This direct coating 11 can be a so-called Sensotect® structure, which detects the torque of the steering shaft 02 and supplies it as a torque signal to the evaluation unit 09 via a connection line 12 (see FIG. 2).

[0027] FIG. 2 shows a top view of the sensor assembly 01 according to FIG. 1. As can be seen in the top view, the circuit board 06 surrounds the steering shaft by having a shaft passage. In a manner not shown further, the circuit board 06 is arranged in a rotationally fixed manner. This can be realized, for example, by fastening to the housing or a bearing on the steering shaft 02. Furthermore, FIG. 2 shows that the connection line 12 spirals around the steering shaft 02 and rests on the circuit board 06. Furthermore, the evaluation unit 09 is located on the circuit board 06, but on the side of the circuit board facing away from the connection line.

LIST OF REFERENCE SYMBOLS

[0028] 01 Sensor assembly [0029] 02 Rotatable shaft [0030] 03 Main body [0031] 04 First additional body [0032] 05 Second additional body [0033] 06 Circuit board [0034] 07 First angle resolver [0035] 08 Second angle resolver [0036] 09 Evaluation unit [0037] 10 Torque sensor [0038] 11 Direct coating [0039] 12 Connection line