Description

The invention concerns a sensor assembly comprising two rotational angle sensors of different type, the sensor assembly having a rotor and a stator, the first rotational an gle sensor having a antenna comprised by the stator and a modulator comprised by the rotor, and the second rotational angle sensor having a magnet and a magnetore sistive element or a hall sensor comprised by the stator.

Such a sensor arrangement is known from the document with the publication number EP 2 180 296 A1. The rotor of this sensor arrangement is coupled to a second rotor via a toothed gear. This second rotor carries the magnet of the second rotation angle sensor. The magnetoresistive element of the second rotation angle sensor is arranged on the stator, which is a common stator for the first rotational angle sensor and the second rotational angle sensor. Instead of the magnetoresistive element a hall sensor may be used.

Through the coupling of the two rotors via the gear mechanism, a rotary motion of the first rotor is transmitted to the second rotor. The gear is designed so that the second rotor has a higher rotational speed than the first rotor. When the first rotor is rotated by a first angle, the second rotor therefore rotates by a different angle. This leads to a high complexity of the evaluation of the sensor signals. In addition, the transmission of motion by means of the gear mechanism can be error-prone. For example, dirt could block the gears, preventing motion transmission and, in the worst case, even damage or destruction of the gears.

A further disadvantage of the known sensor arrangement is that a comparably large installation space is required for accommodating the two rotors. The invention is based on the task of creating a new sensor arrangement of the type mentioned at the beginning, in which an error-prone transmission of motion is dispen sable and the two rotary angle sensors can be accommodated in a compact manner.

According to the invention, this task is solved by the rotor enclosing the magnet. In stead of two rotors, only one rotor is provided at the invention. This eliminates the transmission of motion through a gear mechanism, with all the disadvantages de scribed above.

The rotor of a sensor arrangement according to the invention may have a shaft at one end of which the magnet is arranged. The magnet is preferably attached to one end of the shaft.

The modulator can also be attached to the shaft. The modulator may be provided on a printed circuit board having a circular surface on which one or more conductive tracks are provided to form the modulator. A hole in the printed circuit board can have an in side diameter that corresponds to the outside diameter of the shaft. The modulator can also be a metal part, for example made by punching from a sheet metal. The modulator can also be a part which will modulate the signal coming from the antenna.

The stator may comprise at least one electrical component, in particular an integrated circuit, for supplying power to elements of the first and/or second angle-of-rotation sensor. At least one electrical component, in particular an integrated circuit, may also be provided for evaluating a signal from the antenna and the magnetoresistive ele ment or hall sensor. The components may include filter elements.

The stator may have a printed circuit board on which the antenna, the magnetoresis tive element or hall sensor and at least one electrical component are provided. The antenna can be formed by one or more conductive tracks.

The magnetoresistive element or hall sensor can be located in a projection in the di rection of the axis of rotation within a circular disk concentric to the axis of rotation. The modulator can be located in a projection in the direction of the rotation axis within a circular ring concentric to the rotation axis. The circular disc can be located within the circular ring and have an outer diameter smaller than the inner diameter of the cir cular ring. A zone may be provided between the circular disc and the circular ring to prevent mutual disturbances between the first rotational angle sensor and the second rotational angle sensor, in particular interferences. This zone creates a distance be tween the circular disc and the circular ring which is on the one hand so large that dis turbances are reliably avoided and on the other hand so small that the size of the sen sor arrangement can be so small. In this zone there are preferably no magnetically and/or electrically conductive materials present which could cause an electromagnetic interference of one rotation angle sensor by the other rotation angle sensor. In the zone, however, materials and/or structures can be provided which cause an electro magnetic decoupling of the two rotation angle sensors.

The at least one electrical component for powering the second rotational angle sensor and/or for evaluating a signal from the magnetoresistive element or hall sensor is pref erably located within the circular disc. This allows cables between the magnetoresis tive element or hall sensor and the component to be evaluated to be kept short. Inter ferences that could be coupled in via lines can thus be minimized.

The at least one electrical component for powering the first rotation angle sensor and/or the second rotation angle sensor and/or for evaluating a signal from the an tenna and/or the magnetoresistive element or hall sensor may be located outside the circular ring.

The invention is explained in more detail below based on the attached figures. The fig ures show:

Fig. 1 a perspective side view of a sensor arrangement according to the invention, Fig. 2 a bird's eye view of a stator of the invention sensor arrangement,

Fig. 3 a perspective view of a rotor sensor arrangement according to the invention, and Fig. 4 a representation of zones of the stator.

The stator 1 of the invention sensor arrangement shown has a printed circuit board 11 , on which a antenna 12 is arranged, which is formed by conductor tracks. This antenna 12 has a circular contour, which is provided in a zone C of stator 1.

In a center of zone C, stator 1 has a circular disk-shaped zone A in which a magneto resistive element 13 is provided. The magnetoresistive element is connected to inte grated components 15, which can supply the magnetoresistive element with energy and evaluate a signal of the magnetoresistive element. The components are con nected to each other via lines that are not shown.

A zone B in the form of a circular ring is provided between zone A in the centre and zone C. This zone has the shape of a circular ring. This zone B is for interference sup pression, which will be explained below.

Zone C is enclosed by a zone D that may extend to the edge of printed circuit board 11. In zone D further components are provided, namely components 14, which can be used to generate a signal which is transmitted to the antenna. In addition, components 14 make it possible to receive a signal from the antenna and evaluate this signal.

Rotor 2 of the sensor arrangement according to the invention has a shaft 21. This shaft is mounted turnable, what is not shown. The bearing is designed so that the shaft 21 and all parts of the rotor 2 attached to the shaft are rotatable about a longitu dinal axis of the shaft 21.

The parts of rotor 2 attached to shaft 21 may include a printed circuit board 22 carry ing a modulator formed by a structure of conductive tracks or a metallic part which will modulate the signal coming from the PCB antenna. The printed circuit board 22 has recesses 221 in areas where there are no tracks, which can be reduced by the mass of the printed circuit board. The parts of rotor 2 attached to shaft 21 also include a magnet 23 attached to one end of shaft 21. The magnet 23 has the shape of a flat cylinder, which can have a hole in its center for fixing it on the shaft, which is arranged coaxially to the longitudinal axis.

Rotor 2 is arranged so that it can rotate relative to stator 1 so that zones A, B and C are coaxial with the axis of rotation of rotor 2.

The antenna 12 and the modulator 22 form a first rotation angle sensor of the sensor arrangement and the magnetoresistive element 13 and the magnet 23 form a second rotation angle sensor of the sensor arrangement. The areas in which the sensors are arranged are spatially separated from each other.

The signal generated by one of the components 14 and coupled into the antenna 12 generates an electromagnetic field which is changed by the rotation of the modulator. This change affects the antenna and changes the signal according to the angle of ro tation of the rotor to the stator. The signal can be received by one of the components 14 for evaluation by the antenna.

The second rotation angle sensor can be based on the anisotropic magnetoresistive effect, the giant magnetoresistance effect, the tunnel magnetoresistance effect or any other magnetoresistive effect or the hall effect. By the relative movement of the mag net 23 and the magnetoresistive element 13, the magnetoresistive element

13 generates a signal corresponding to the angle of rotation that can be evaluated with one of the components 15. Thus, both the first rotation angle sensor and the sec ond rotation angle sensor provide the rotation angle of rotor 2 to stator 1 , which can be further evaluated.

Zone B is used to prevent interference between the first rotation angle sensor and the second rotation angle sensor. It is as large as necessary so that disturbances can be safely avoided, but at the same time so small that the rotor and stator take up as little space as possible. Zone D surrounding zone C is defined so that no other component is interfering with the first rotation angle sensor.

Because the integration aspect of sensor arrangement is very important, these zones B and D must be sized as small as possible so that the redundant sensor arrangement is taking as less space as possible.

reference character list

1 stator

11 printed circuit boards

12 antenna

13 magnetoresistive element

14 components for generating a transmission signal and evaluating a signal of the antenna

15 components for the evaluation of a signal of the magnetoresistive sensor.

2 rotor

21 shank

22 modulator

221 recesses

23 magnet

A zone of the printed circuit board of the stator for the magnetoresistive sensor and components

B zone for decoupling of the first and second angle sensors

C zone of the printed circuit board of the stator for the antenna

D zone depicted by any surface cohesive to stator 1 being outside of zone C