DE102013218734A1 - A sensor for outputting an electrical signal based on a path to be detected - Google Patents

Abstract

A sensor (16) for outputting an output signal dependent on a rotation angle (18) is disclosed, comprising a shaft (34) rotatable about the angle of rotation (18), a rocker element fixed non-rotatably to one axial end (39) of the shaft (34) (30) for outputting a physical measuring field (32) and having an air gap (31) spaced from the field generator element (30) arranged evaluation circuit (28) for generating the output signal based on the physical measuring field (32), wherein the rim encoder element (30) so is formed, that the air gap (31) in dependence of the rotation angle (18) is variable.

Description

The invention relates to a sensor for outputting an electrical signal based on a path to be detected, in particular an angle and a method for producing a sensor, in particular of the angle sensor.

From the WO 2006/029 946 A1 is a sensor with a field-detecting element in the form of a transmitter magnet and an evaluation circuit for detecting a magnetic field emitted by the encoder magnet known. The transmitter magnet can be moved over a path to be detected, such as a rotation angle, wherein the evaluation circuit detects the rotation angle based on the magnetic field emitted by the encoder magnet and outputs in an output signal. The sensor is therefore also called an angle sensor.

It is an object of the invention to improve the known sensor.

The object is solved by the features of the independent claims. Preferred developments are the subject of the dependent claims.

According to one aspect of the invention, a sensor for outputting an output signal dependent on a rotation angle comprises a shaft rotatable about the rotation angle, a rim encoder element fixed for rotation at one axial end of the shaft for outputting a physical measurement field and an evaluation circuit arranged at an air gap spaced from the field sensor element for generating the output signal based on the physical measuring field, wherein the rim encoder element is designed such that the air gap is variable in dependence on the rotation angle.

The specified sensor is based on the consideration that the field-sensor element could be formed in a circle around an axis of rotation of the shaft. In this way, in each rotation angle of the shaft, a part of the field-generating element and thus of the physical measuring field would be directed to the evaluation circuit, so that the rotation angle of the shaft would be detectable in principle over a complete rotation of the shaft. On the other hand, however, the physical measuring field of a single field pole emitted by the field-emitting element is insufficient, so that the evaluation circuit can detect the rotation angle of the shaft based on the physical measuring field, because the physical measuring field would have to change as a function of the angle of rotation.

For this purpose, although a dipole, such as a magnet could be used as a field sensor element, in which the physical measuring field is composed of a superposition of two subfields, which are delivered from one field pole. At certain angles of rotation, however, a field pole with its subfield dominates the physical measuring field so strongly that the other subfield no longer has any influence on the physical measuring field. The physical measuring field can therefore continue to change in these rotation angle ranges depending on the angle of rotation, so that no clear detection of the rotation angle is possible.

In order to still enable the unambiguous detection, a variable air gap between the field generator element and the evaluation circuit is used as a function of the angle of rotation within the scope of the specified sensor. In this way, not only the physical measuring field itself, but also its effect, which it has on the evaluation circuit varies depending on the angle of rotation. As a result, the evaluation circuit can generate an output signal which is dependent on the angle of rotation independently of whether or not the physical measuring field changes as a function of the angle of rotation.

The variable air gap is defined as a function of the angle of rotation as the shortest distance between the field sensor element and the evaluation circuit.

In a development of the specified sensor, the field sensor element in the circumferential direction to the angle of rotation considered two, for example, the aforementioned field poles, wherein the variable air gap is lowest, if one of the two field poles lies on a line through a rotation axis of the shaft and the evaluation circuit. In this way, the largest signal jumps can be achieved in the evaluation signal depending on the rotation angle, so that the rotation angle can be detected with a maximum sensitivity.

The variable air gap can be arbitrarily formed, for example, by an axially helical field transmitter element. In a particular embodiment of the specified sensor, the variable air gap is formed by the use of at least one radially and / or axially protruding from the field sensor element projection. Expediently, the variable air gap should be realized by geometrical measures on the field-emitting element and / or on the evaluation circuit, which is technically feasible in terms of cost and time.

In another refinement of the specified sensor, the variable air gap is formed by at least two projections projecting radially and / or axially from the field generator element, which are arranged point-symmetrically with respect to each other. On In this way, a symmetrical output signal can be output via the rotation angle, which is particularly easy to evaluate computationally.

In a still further development of the specified sensor, the projection in the direction of the angle of rotation is substantially equal to a detection range of the evaluation circuit in the direction of the angle of rotation. In this way, the occurrence of a constant output signal over a range of values of the rotation angle can be avoided even better.

In an alternative development of the specified sensor, the field-transmitting element is elliptical in the axial and / or radial direction as viewed from the shaft for the evaluation circuit. The elliptical field generator element forms an output signal as a function of the angle of rotation, which approximates a sinusoidal shape and is largely free of harmonics. From such a sinusoidal signal, the rotation angle can be derived in a technically particularly simple manner.

The physical measuring field can be designed as desired. Particularly preferably, the physical measuring field is a magnetic field. In a preferred embodiment of the specified sensor, the field-emitting element is therefore a magnet which can be used as a permanent magnet without electrical power supply in the sensor.

In a particularly preferred development of the specified sensor, the field-emitting element is arranged axially spaced from the shaft and radially spaced from a rotational axis of the shaft, which can be represented on a particularly small space.

According to a further aspect of the invention, a method for producing a sensor configured for outputting an output signal dependent on a rotation angle, in particular one of the above sensors, comprises the steps of providing a shaft rotatable about the rotation angle injection molding of a field sensor element arranged for outputting a physical measuring field to an axial one End of the shaft, and arranging an evaluation circuit seen from the shaft axially in front of the field generator element, which is adapted based on the physical measuring field to produce the output signal.

In a further development, the specified method comprises the step of forming an anti-twist device at the axial end prior to injection of the field-transmitting element.

In yet another development of the specified method, a material of the field-emitting element sprayed onto the shaft comprises a filler in which magnetic particles are accommodated.

According to a further aspect of the invention, a sensor for outputting an output signal dependent on a rotation angle is produced according to one of the stated methods.

The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings, in which:

1 1 is a schematic view of a vehicle with a chassis control system;

2 a sensor for detecting acceleration between a wheel and a chassis in the vehicle 1 .

3 in a perspective view of a part of the sensor from the 2 ;

4 in a partial sectional view of a part of a shaft into which a field sensor element for the sensor 2 is injectable, and

5 in a partial sectional view of the part of the shaft 4 to which the field sensor element for the sensor 2 injected, show.

In the figures, the same technical elements are provided with the same reference numerals and described only once.

It will open 1 Reference is made to a schematic view of a vehicle 2 with a chassis control system 4 shows.

As part of this suspension control system 4 should lift, pitch and roll a chassis 6 opposite a road, not shown on the stationary wheels 8th of the vehicle 2 in a vertical axis 10 Stationary rolling minimized to the driving characteristics of the vehicle 2 when driving in one direction of travel 12 to improve.

For this purpose, the chassis control system in an example from the DE 10 2005 060 173 A1 known manner a control device 14 on, in the present embodiment off on each wheel 8th arranged angle sensors 16 angle of rotation 18 receives a relative position of the corresponding wheel 8th opposite the chassis 6 describe. The rotation angle 18 will not go further referenced output signals between the angle sensors 16 and the control device 14 transfer. Based on the differences of these angles of rotation 18 determines the control device 14 whether the chassis 6 in the vertical axis 10 moves, ie performs a lifting movement, or whether the chassis 6 staggers or nods and steers. In this case, the control device calculates 14 one of these lifting, rolling and / or pitching counteracting counter-movement and controls with appropriate control signals 20 at the wheels 8th arranged active struts 22 on to the chassis 6 to compensate for this countermovement. As active struts 22 For example, those from the DE 101 22 542 B4 known struts are used.

To take into account, for example, when cornering caused by the road position lifting, rolling and / or pitching movements, the control device, a suitable setpoint 24 be supplied.

It will open 2 Reference is made to the example of an angle sensor 16 out 1 is shown.

The angle sensor 16 in the present embodiment has one in the vertical axis 10 stationary with the chassis 6 connectable circuit housing 26 on. These are on the circuit housing 26 not visible mounting holes 27 formed, by which a not further shown fastening means, such as a screw can be performed. In the circuit housing 26 is an evaluation circuit 28 housed by a donor element to be described in the form of a magnet 30 a physical field in the form of a magnetic field 32 receives. The magnet 30 is from the evaluation circuit 28 with an air gap 31 complained of the rotation angle in the present embodiment 18 is dependent. This will be discussed later. Through a passage opening 34 of the circuit housing 26 is one about a rotation axis 37 rotatable encoder shaft 38 picked up, where the magnet 30 at an axial end 39 is held. From the magnet 30 opposite axial end 40 of the encoder housing 38 a lever protrudes at right angles 41 from, at its radial end a mounting hole 42 is formed, at which the angle sensor 16 in the vertical axis 10 stationary with one of the wheels 6 is connectable.

Moves the corresponding wheel 6 in the vertical axis 10 opposite the chassis 6 , so the wheel moves 6 also the lever 41 and thus rotates the encoder shaft 38 opposite the circuit housing 26 with the angle of rotation to be transmitted 16 , This also moves the magnetic field 32 opposite the evaluation circuit 28 with the angle of rotation 18 , The moving magnetic field 32 changes depending on the angle of rotation 18 opposite the evaluation circuit 28 in its magnetic field strength, what of the evaluation circuit 28 metrologically, for example, a known per se Hall element in the evaluation circuit 28 captured and at an output interface 46 in one the angle of rotation 18 carrying not shown output signal in the in 1 shown manner to the control device 14 can be transferred.

The angle sensor 16 will be described below on the basis of 3 be explained in more detail.

As in 3 to see is the magnet 30 elliptical in the present embodiment. Here is the magnet 30 in the axis of rotation 37 the encoder shaft 38 Seen in both an axial cross-section and in a radial cross section elliptical constructed. In principle, however, it would also be possible to use the magnet 30 but also form elliptical only in a radial or axial cross-section.

The field poles, at the magnet 30 a north pole 50 and a south pole 52 are separated in the present embodiment by the minor axes of the elliptical cross sections, so that the field poles 50 . 52 in the present embodiment, in the main vertices 54 of the elliptical shaped magnet 30 lie. Alternatively, however, the field poles could also be separated by the major axes of the elliptical cross sections.

By elliptical formation of the magnet 30 in the axial cross section of the magnet 30 be on the magnet 30 two axial projections 56 formed in the radial direction of the axis of rotation 37 the encoder shaft 38 from the magnet 30 jump out. According to the elliptical design of the magnet 30 in a radial cross section, two projections 58 formed in the axial direction of the axis of rotation 37 from the magnet 30 jump out. Due to the elliptical design of the magnet 30 are the field poles 50 . 52 point symmetric to a point of symmetry 59 on the axis of rotation 37 educated.

Through the projections 56 . 58 becomes the air gap 31 depending on the angle of rotation 18 variably formed. That means the shortest distance between the magnet 30 and the evaluation circuit 28 depending on the angle of rotation 18 varied. The variable air gap 31 causes the magnetic field strength of the magnetic field 32 of the magnet 30 not only by the movement of the magnet 30 itself but also through this varying air gap 31 depending on the angle of rotation 18 is changed. This can be the angle of rotation 18 in the from the evaluation circuit 28 Output signal output not only based on the movement of the magnets 30 itself but also based on the variation of the air gap 31 be generated.

In particular, the protruding in the axial direction projection 58 should be in the circumferential direction of the axis of rotation 37 and thus in the direction of the rotation angle 18 as accurately as possible in a detection area 60 the evaluation circuit 28 fit in which the magnetic field 32 of the magnet 30 is detected. In this way it is ensured that the variable air gap 31 in any position based on a change in the angle of rotation 18 changed and a change in the output signal from the evaluation circuit 28 leads.

The magnet 30 can the axial end 39 the encoder shaft 38 be sprayed. This is done first on the 4 Reference is made to the encoder shaft 38 shown in a state before the magnet 30 to the encoder shaft 38 is injected.

At the axial end 39 the encoder shaft 38 is in the present embodiment an elliptical and oily holding element 62 formed in the two walls 64 are included, as an anti-rotation device for the magnet 30 should serve.

In this oily holding element 62 a magnetic material is injected. As a magnetic material, for example, a plastic such as polyamide, polyphenylene sulfide or the like can be used as a filler. In this plastic, a magnetic powder, for example, based on hard ferrite or NdFeB-based embedded. The magnetization of the injected material can be done directly during the injection or after the injection process is completed.

Alternatively, at the axial end 39 the encoder shaft 38 a magnet prepared beforehand, for example, by sintering, for example, be attached by gluing.

In 5 is an example of a molded magnet 30 shown in which the magnet 30 an axially aligned projection 58 having.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2006/029946 A1 [0002]
• DE 102005060173 A1 [0030]
• DE 10122542 B4 [0030]

Claims (10)

Sensor ( 16 ) for outputting one of a rotation angle ( 18 ) dependent output signal comprising one about the rotation angle ( 18 ) rotatable shaft ( 34 ), a rotationally fixed at one axial end ( 39 ) the wave ( 34 ) fixed field element ( 30 ) for outputting a physical measuring field ( 32 ) and one with an air gap ( 31 ) spaced apart from the field transmitter element ( 30 ) arranged evaluation circuit ( 28 ) for generating the output signal based on the physical measuring field ( 32 ), wherein the field generator element ( 30 ) is designed such that the air gap ( 31 ) as a function of the angle of rotation ( 18 ) is changeable. Sensor ( 16 ) according to claim 1, wherein the variable air gap ( 31 ) as a function of the angle of rotation ( 18 ) as the shortest distance between the field generator element ( 30 ) and the evaluation circuit ( 28 ) is defined. Sensor ( 16 ) according to claim 1 or 2, wherein the field-emitting element ( 30 ) in the circumferential direction to the angle of rotation ( 18 ) considers two field poles ( 50 . 52 ) and the variable air gap ( 31 ) is lowest when one of the two field poles ( 50 . 52 ) parallel to a line through a rotation axis ( 37 ) the wave ( 38 ) and the evaluation circuit 28 lies. Sensor ( 16 ) according to any one of the preceding claims, wherein the variable air gap ( 31 ) by at least one radially and / or axially from the field sensor element ( 30 ) protruding projection ( 56 . 58 ) is trained. Sensor ( 16 ) according to any one of the preceding claims, wherein the variable air gap ( 31 ) by at least two radially and / or axially projecting from the field sensor element projections ( 56 . 58 ) is formed, the point-symmetrical to each other ( 59 ) are arranged. Sensor ( 16 ) according to one of claims 4 or 5, wherein the projection ( 56 . 58 ) is substantially equal to a detection area ( 60 ) of the evaluation circuit ( 28 ) in the direction of the angle of rotation ( 18 ). Sensor ( 16 ) according to one of the preceding claims, wherein the field-generating element ( 30 ) from the wave ( 38 ) off to the evaluation circuit ( 28 ) Is viewed in the axial and / or radial direction elliptical. Sensor ( 16 ) according to one of the preceding claims, wherein the field-generating element ( 30 ) a magnet ( 30 ). Sensor ( 16 ) according to one of the preceding claims, wherein the field-generating element ( 30 ) axially spaced from the shaft ( 38 ) and radially spaced from a rotation axis ( 37 ) the wave ( 38 ) is arranged. Method for producing a for outputting one of a rotation angle ( 18 ) dependent output signal equipped sensor ( 16 ), in particular according to one of the preceding claims, comprising - providing a rotation angle ( 18 ) rotatable shaft ( 38 ), - injecting one to output a physical measuring field ( 32 ) field element ( 30 ) to an axial end ( 39 ) the wave ( 38 ), so that with the field generator element ( 32 ) based on the angle of rotation ( 18 ) the physical measuring field ( 32 ), and - arranging an evaluation circuit ( 28 ) from the wave ( 38 ) seen axially in front of the field sensor element ( 30 ), which is set up based on the physical measuring field ( 32 ) to produce the output signal.

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