DE102018106438A1 - Sensor arrangement with a Multipolencoder and rotary bearing with such a sensor arrangement - Google Patents

Abstract

The present invention relates to a sensor arrangement comprising: a multipole encoder (10) of a plurality of mutually adjacent pole pairs (12) which provide a scanning plane with magnetic north and south poles alternately arranged in a scanning direction (X); at least one magnetic field sensor having a sensor surface, wherein the Multipolencoder (10) in the scanning direction (X) is movable relative to the magnetic field sensor, so that a scanning magnetic field with alternating polarity passes through the sensor surface, the scanning field strength between adjacent poles each have a zero crossing shows. The sensor arrangement is characterized in that the boundary lines (13) between adjacent pole pairs (12) of the Multipolencoders (10) are designed such that the duty cycle of the signal of the magnetic field sensor when moving the Multipolencoders in the scanning direction (X) changes, if at the same time Movement of the multipole encoder takes place in a direction perpendicular to the scanning direction (Y), while the total width of the pole pair with the north pole and south pole remains the same, the duty cycle corresponds to the ratio of the north pole width to the total width of the pole pair with north pole and south pole.

Description

The present invention relates to a sensor arrangement comprising a multipole encoder and a magnetic field sensor. The invention further relates to a rotary bearing with such a sensor arrangement.

The multipole encoder provides a scanning plane formed of a plurality of magnetic poles consecutive in a scanning direction. The Multipolencoder consists of several mutually adjacent pole pairs, wherein the magnetic field alignment of each successive pole pairs alternates. The magnetic field sensor may be formed, for example, as a magnetoresistive sensor or Hall sensor.

In order to be able to detect rotational or linear movements with the sensor arrangement, the multipole encoder is movable relative to the magnetic field sensor in the scanning direction, during which movement the desired sensor signal is generated. During the relative movement, a scanning magnetic field of alternating polarity, which is generated by the successive magnetic poles, passes through a sensor surface of the magnetic field sensor.

Numerous sensor arrangements are known from the prior art, which serve the non-contact detection of a relative movement between two machine parts. Such sensor arrangements are used, for example, in rotary bearings for detecting the rotational speed. At wheel bearings with such sensor arrangements, the rotational speeds of the vehicle wheels and therefrom the respective rotational speeds are determined.

The EP 0 736 183 B1 shows a motor vehicle wheel sensor for detecting rotational or angular movements of wheels. The wheel sensor comprises a transmitter, which has permanent magnetic, in the direction of rotation with alternating polarity successive areas. Another component of the wheel sensor is a magnetoresistive sensor with a bias magnet. The bias magnet generates a magnetic field oriented perpendicular to the direction of movement of the transmitter. During the rotational movement, the permanent magnetic areas of the transmitter generate in a preferred direction of the sensor element, which is orthogonal to the magnetic field components generated by the biasing magnet, a variable field strength course between the adjacent permanent magnetic areas, which penetrates the sensor element in the direction of rotation and reflects the rotational movement.

The DE 10 2007 023 385 A1 describes a device for non-contact detection of linear or rotational movements. The device comprises a stationary magnetoresistive chip sensor and an adjacent, movable magnetic field transmitter device, the individual magnet segments in their polarity alternately in z Direction are magnetized. The chip sensor is with its sensor surface in the xy Level or the xz Plane aligned such that the measuring direction and the sensor surface in x Direction.

From the DE 100 10 042 A1 a linear transducer for motor vehicles is known. The displacement transducer includes an axially displaceable element with which an encoder is positively connected. The displacement transducer further comprises a stator, with which at least one sensor module is firmly connected. The displaceable element is guided by a bearing connected to the stator, which encompasses and axially guides the displaceable element. The detection of the movement can be done either by direct measurement of the magnetic field generated by the encoder or by detecting the polarization change.

A disadvantage of the known solutions is that movements can be detected only in one direction.

It is an object of the present invention to provide an improved sensor assembly utilizing a multi-level encoder having a scanning plane of a plurality of magnetic poles contiguous in a scanning direction and detection of movements in the scanning direction and, in addition, detection of movements, from known sensor arrangements for non-contact relative movement detection of the multipole encoder perpendicular to the scanning direction.

This object is achieved by a sensor arrangement according to the appended claim 1.

The sensor arrangement according to the invention initially comprises, in a known manner, a multipole encoder having a scanning plane of a plurality of magnetic poles successive in a scanning direction. The successive poles are provided by juxtaposed pole pairs, which have alternating magnetic field alignments, so that in the scanning plane next to a north pole of a first Polpaares a south pole of an adjacent second pair of poles, which in turn is followed by a north pole of an adjacent third Polpaares etc. Furthermore, the sensor arrangement comprises at least a magnetic field sensor with a sensor surface. The multipole encoder is movable in the scanning direction relative to the magnetic field sensor. By the Sensor surface runs during this movement in the scanning direction, a variable magnetic field with alternating polarity. The signal then generated by the magnetic field sensor has a sinusoidal shape that reflects the alternating polarity of the magnetic areas. At constant moving speed in the scanning direction, the period of this sinusoidal signal is also constant. The width of the positive sine half-wave, which is generated for example when passing through the magnetic north pole, and the width of the negative sine half-wave, which is generated when passing through the magnetic south pole, for example, are then the same size. The duty cycle is the ratio of the north pole to the total pole width or the equivalent duration in the sinusoidal sensor signal and is 0.5 and 50% for the same large north and south pole. According to the invention, the boundary lines between adjacent pole pairs of the Multipolencoders are formed such that this duty cycle changes when a relative displacement between Multipolencoder and magnetic field sensor takes place perpendicular to the scanning direction, while the total width from north to south pole remains the same for movement in the scanning direction. This ensures that detection of the movement speed in the scanning direction can be carried out by evaluating the time duration from rising to rising or falling to falling edge of the sinusoidal sensor signal even with a modified duty cycle.

A significant advantage of the sensor arrangement according to the invention is that due to the special design of the boundary lines between adjacent pole pairs of the multipole encoder in addition to the running direction in the scanning direction also perpendicular to the scanning direction running movements can be detected. For this purpose, the duty cycle, ie the ratio of the north pole width to the total width from north pole to south pole, is evaluated. If the duty cycle changes, relative motion between the magnetic field sensor and the multipole encoder occurred perpendicular to the scan direction. The solution according to the invention can be realized with little effort without additional design effort.

The boundary lines between adjacent pole pairs can be realized in many different ways. Some embodiments are mentioned below by way of example, wherein no restriction is to be made to the stated embodiments, other suitable embodiments are quite conceivable. According to a first embodiment, the boundary lines between adjacent pole pairs on a tooth-shaped course. In this embodiment, the duty cycle changes linearly, so that small movements cause only small changes in the duty cycle. In an alternative embodiment, the boundary lines between adjacent pole pairs on a curved course. The change in the duty cycle is non-linear in this embodiment. Even small movements cause a relatively large change in the duty cycle. Furthermore, the boundary lines between adjacent pole pairs may have a step-shaped course. Due to the stepped course, the duty cycle changes abruptly. Although the resolution is thereby lower, but the changes in the duty cycle at the stages are clearer.

An advantageous embodiment uses a sensor arrangement with two magnetic field sensors, which are arranged in phase opposition to one another. When using a sensor element, the amplitude of the sensor signal is dependent on the position in the scanning direction and the position in the direction perpendicular to the scanning direction. In movements perpendicular to the scanning direction, the amplitude of the sensor signal changes linearly. There is also an additional temperature dependence. The determination of the position in the direction perpendicular to the scanning direction is thus not clear. The use of two phase-shifted magnetic field sensors has the advantage that, regardless of the magnetic track position in the scanning direction, the difference between the two sensor signals is always the same. Thus, there is only a temperature dependence. If at standstill, d. H. If no movement takes place in the scanning direction, a displacement perpendicular to the scanning direction, conclusions can be drawn on the situation by comparing the amplitudes of the sensor signals. This is independent of the temperature.

The magnetic field sensor may be designed in semiconductor construction and use a magnetoresistive effect or the Hall effect. However, it should not be limited to the mentioned magnetic field sensors, other suitable magnetic field sensors are possible.

The multipole encoder may extend both in a flat plane and along a curved plane. It can for example be part of a linear bearing or a rotation bearing.

According to an advantageous embodiment, the sensor arrangement can be connected to an evaluation device. In this context, it has proven expedient to equip the sensor device with a connecting cable for connection to an evaluation unit. However, alternative embodiments are also possible in which the data transmission to the evaluation unit does not take place via cable but wirelessly, preferably by means of a radio signal.

The rotary bearing according to the invention comprises two relatively rotatable machine parts and the sensor arrangement described above, which serves to detect the rotational speed. The rotary bearing may be formed, for example, as a wheel bearing.

• 1 eine schematische Darstellung einer ersten Ausführungsform eines Multipolencoders für eine erfindungsgemäße Sensoranordnung;
• 2 drei Diagramme des Verlaufs des Ausgangssignals der erfindungsgemäßen Sensoranordnung;
• 3 eine perspektivische Darstellung einer Sensoranordnung gemäß dem Stand der Technik;
• 4 ein Diagramm des Verlaufs des Ausgangssignals der Sensoranordnung gemäß dem Stand der Technik;
• 5 einen ringförmigen Multipolencoder gemäß dem Stand der Technik;
• 6 eine schematische Darstellung von zwei Ausführungsformen der erfindungsgemäßen Sensoranordnung, welche den Multipolencoder gemäß 1 nutzen;
• 7 ein Diagramm des Verlaufs der Signalamplituden der bei den Ausführungsformen gemäß 6 verwendeten Magnetfeldsensoren;
• 8 eine ringförmige Ausführung des Multipolencoders gemäß 1;
• 9 eine schematische Darstellung einer zweiten Ausführungsform des Multipolencoders;
• 10 eine schematische Darstellung einer dritten Ausführungsform des Multipolencoders;
• 11 eine schematische Darstellung einer vierten Ausführungsform des Multipolencoders;
• 12 eine Querschnittsansicht eines erfindungsgemäßen Rotationslagers. Nachfolgend wird für ein leichteres Verständnis zunächst anhand der 3, 4 und 5 eine herkömmliche Sensoranordnung gemäß dem Stand der Technik beschrieben.

Preferred embodiments of the invention will be explained in more detail with reference to the accompanying figures. Show it:

• 1 a schematic representation of a first embodiment of a Multipolencoders for a sensor arrangement according to the invention;
• 2 three diagrams of the course of the output signal of the sensor arrangement according to the invention;
• 3 a perspective view of a sensor arrangement according to the prior art;
• 4 a diagram of the course of the output signal of the sensor arrangement according to the prior art;
• 5 a ring-shaped multipole encoder according to the prior art;
• 6 a schematic representation of two embodiments of the sensor arrangement according to the invention, which the Multipolencoder according to 1 use;
• 7 a diagram of the course of the signal amplitudes of the embodiments according to 6 used magnetic field sensors;
• 8th an annular embodiment of the Multipolencoders according to 1 ;
• 9 a schematic representation of a second embodiment of the Multipolencoders;
• 10 a schematic representation of a third embodiment of the Multipolencoders;
• 11 a schematic representation of a fourth embodiment of the Multipolencoders;
• 12 a cross-sectional view of a rotation bearing according to the invention. The following is for the sake of easier understanding, first on the basis of 3 . 4 and 5 a conventional sensor arrangement according to the prior art described.

3 shows a perspective view of the sensor arrangement according to the prior art. The sensor arrangement comprises a magnetic field sensor 01 with a sensor surface and a Multipolencoder 02 , The multipole encoder 02 is shown by way of simplification as an elongated band. As in 5 shown, the Multipolencoder 02 be designed as an encoder ring. He has numerous magnetic pole pairs in all types 03 , which are arranged side by side with alternating magnetic field alignment. The resulting chain from the pole pairs 03 extends in a scanning direction X which is the relative direction of movement between the magnetic field sensor 01 and the multipole encoder 02 equivalent. Which is between the adjacent pole pairs 03 forming magnetic fields are characterized by the magnetic field lines 04 symbolizes. The borderlines 05 between each adjacent pole pairs 03 parallel to each other and at right angles to the scanning direction X , The by means of magnetic field sensor 01 detected signal can 4 be removed. The upper diagram shows the electrical sinusoidal signal generated in the magnetic field sensor following the changing magnetic polarity of the multipole encoder. In the lower diagram, the digital signal generated from this sinusoidal signal is shown, by means of which the relative movement speed in the scanning direction is determined, for example by determining the time duration from rising to rising or from falling to falling signal edge. The generation of this digital signal can already take place in the magnetic field sensor or in a separate evaluation unit connected to it. With the sensor arrangement according to the prior art, movements in the scanning direction X be recorded.

1 shows a schematic representation of a first embodiment of a Multipolencoders for a sensor arrangement according to the invention. The multipole encoder 10 owns as the previously known Multipolencoder 02 a magnetic track with numerous magnetic pole pairs 12 , which are arranged side by side with alternating magnetic field alignment. In contrast to the previously known Multipolencoder 02 the borderlines run 13 between each adjacent pole pairs 12 the multipole encoder according to the invention 10 but not at right angles to each other. The borderlines 13 instead have a non-perpendicular to the scanning direction, in the illustrated embodiment tooth-shaped course. In addition to the movements in the scanning direction X With the sensor arrangement according to the invention thereby also movements perpendicular to the scanning direction X , in Y Direction, be detected. A magnetic field sensor (not shown) may, for example, in Y Direction nominal in position a, so be positioned in the middle of the magnetic track. The width of detectable by magnetic field sensor north and south poles in position a is the same size. The duty cycle, ie the ratio of the north pole width T _p to the total width T of the pole pair is 0.5 or 50%. The course of the sinusoidal sensor signal of the magnetic field sensor positioned in position a can be seen from the upper diagram in FIG 2 be removed. Now happens at the same time to move in X Direction a relative shift between the Magnetic field sensor and the magnetic track in Y Direction, the detected north and south pole widths change while the total width T the pole pair with north and south pole remains the same.

The duty cycle at a in position b that is, with an offset of + Y compared to the center line a, positioned magnetic field sensor is less than 50%. At one in location c that is, with an offset of -Y In contrast to the center line a, positioned magnetic field sensor, the duty cycle will be greater than 50%. The course of the sensor signal of the positioned in position b magnetic field sensor can the lower diagram in 2 be removed. The middle diagram of the 2 shows the course of the sensor signal of the positioned in position c magnetic field sensor.

From the sensor signal thus two movement information can be derived. On the one hand, movements in X Direction by classical evaluation of the times between the pole transitions, for example from rising to rising edge. On the other hand, the location in Y Direction and its change by evaluating the duty cycle T _p / T are recorded. The movement in X Direction can be along both a linear and a rotative path. For rotational paths, both an axially and a radially arranged magnetic track is possible.

8th shows, for example, an annular multipole encoder 10 which is axially magnetized. In Y Direction, the relative movements can be caused for example by dynamic deformations. By measuring and evaluating the duty cycle is thus a conclusion on this deformation and with appropriate knowledge of the ambient and operating conditions on the underlying cause, for example force, torque, possible. The evaluation of the duty ratio is simpler and more efficient than z. B. for a downstream evaluation. B the evaluation of signal amplitudes, especially at high speeds in X -Direction.

6 shows two embodiments of the sensor arrangement according to the invention, which the Multipolencoder according to 1 use. The two versions differ by the number and positioning of the magnetic field sensors used 14 , According to a first embodiment, a in position a positioned magnetic field sensor 14 used. When using a magnetic field sensor 14 the amplitude is dependent on the position in X - and Y -Direction. Can not find movement X Direction, but a shift in Y Direction, no duty cycle can be evaluated. However, there is an approximately linear change in amplitude. The amplitude is also temperature dependent, due to the temperature coefficient of the magnetic encoder material of the device. The position determination in Y Direction is thus faulty.

The second embodiment of the sensor arrangement according to 6 uses two magnetic field sensors 14 . 14b , what a X Out of phase with each other, and in Y Direction, in position c and b, are arranged. In this arrangement, to detect the movement in X Direction uses the difference signal of the two magnetic field sensors. The resulting amplitude of this difference signal when moving in X Direction is still dependent on the temperature, what is the motion detection in X However, the direction plays only a minor role, since the zero crossings of the difference signal are evaluated. As with the first arrangement with only one magnetic field sensor takes place during movement in X Direction at the same time the detection of a movement in Y Direction by the evaluation of the duty cycle of the difference signal. At standstill in X Direction and sole movement in Y Direction, this Y-movement can be detected by separate evaluation of the amplitudes of the two magnetic field sensors. This evaluation is still unambiguous under the influence of temperature. At complete standstill in X - and Y Direction and simultaneous temperature change, eg temperature increase, both amplitudes change to the same extent, ie they are both lower. When moving in Y However, the amplitudes change in opposite directions, ie one increases, while the other decreases, due to the changed Polflächengröße below the sensors. This is in the lower diagram of the 7 seen. The lengths of the arrows correspond to the respective amplitudes.

9 shows a schematic representation of a second embodiment of the Multipolencoders 10 , The borderlines 13 between adjacent pole pairs 12 here have a curved course. With the magnetic field sensor (not shown) positioned in position a, the duty cycle ≠ is 50%. The change in the duty cycle for relative movement in Y Direction is non-linear and thus stronger than in the embodiment according to 1 ,

10 shows a schematic representation of a third embodiment of the Multipolencoders 10 , The borderlines 13 between adjacent pole pairs 12 have a stepped course. The duty cycle changes abruptly in this embodiment. The resolution in Y Direction is lower. For this, the changes in the duty cycle at the stages are clearer.

11 shows a schematic representation of a fourth embodiment of the Multipolencoders 10 , In this embodiment, the duty cycle changes regardless of the relative movement in Y Direction always the same. A conclusion on the direction of movement is therefore not possible. However, movements can be recorded in absolute amounts.

12 shows a cross-sectional view of a rotation bearing according to the invention. The rotary bearing 15 includes an outer ring 17 and one relative to the outer ring 17 rotatable inner ring 18 , Between outer ring 17 and inner ring 18 are inside a rolling element space 19 rolling elements 20 ,

Another part of the rotation warehouse 15 is the already described sensor arrangement which the Multipolencoder 10 and the magnetic field sensor 14 includes. The multipole encoder 10 is designed as an encoder ring with magnetization in the axial direction, which rotatably via a press fit on an outer surface of the inner ring 18 is attached. The multipole encoder 10 has an L-shaped cross-section in the embodiment shown. However, it is not intended to be limiting to multipole encoders 10 take place with L-shaped cross-section. Alternative embodiments may utilize double-L, S-shaped, C-shaped or U-shaped multi-pole encoders. Other suitable cross-sectional shapes of the multipole encoder 10 are possible. Likewise, a radial orientation of the magnetic track, respectively the magnetization is conceivable. The multipole encoder 10 includes in the embodiment shown a carrier 22 on which the magnetic track with the pole pairs 12 is applied. Under load, for example due to acting forces or moments, there is a tilting α between the inner ring 18 with the multipole encoder 10 and the outer ring 17 instead of. This results in a relative displacement of the sensor read point from its nominal position, from which a change in the duty cycle results.

LIST OF REFERENCE NUMBERS

01

Magnetfeldsensor

02

Multipolencoder

03

Polpaare

04

Magnetfeldlinien

05

Grenzlinien

State of the art:

01

magnetic field sensor

02

multipole

03

pole pairs

04

magnetic field lines

05

boundary lines

10

Multipolencoder

11

-

12

Polpaare

13

Grenzlinien

14

Magnetfeldsensor

15

Rotationslager

16

-

17

Außenring

18

Innenring

19

Wälzkörperraum

20

Wälzkörper

21

-

22

Träger

Invention:

10

multipole

11

-

12

pole pairs

13

boundary lines

14

magnetic field sensor

15

rotary bearings

16

-

17

outer ring

18

inner ring

19

anti-friction

20

rolling elements

21

-

22

carrier

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

• EP 0736183 B1 [0005]
• DE 102007023385 A1 [0006]
• DE 10010042 A1 [0007]

Claims (10)

A sensor arrangement comprising: - a multipole encoder (10) comprising a plurality of mutually adjacent pole pairs (12) which provide a scanning plane with magnetic north and south poles alternately arranged in a scanning direction (X), the total width of each pole pair being north pole and south pole constant; at least one magnetic field sensor (14) having a sensor surface, wherein the multipole encoder (10) is movable relative to the magnetic field sensor (14) in the scanning direction (X), so that a directional magnetic field of alternating polarity passes through the sensor surface. Field strength between adjacent poles each shows a zero crossing, wherein the duty cycle of the signal of the magnetic field sensor (14) corresponds to the ratio of the north pole width to the total width of the pole pair with north pole and south pole; characterized in that the boundary lines (13) between adjacent pole pairs (12) of the Multipolencoders (10) are formed such that when moving the Multipolencoders (10) in the scanning direction (X) and simultaneous movement of the Multipolencoders (14) in a perpendicular to the scanning direction (X) extending direction (Y), the duty cycle of the signal of the magnetic field sensor (14) changes. Sensor arrangement after Claim 1 , characterized in that the boundary lines (13) between adjacent pole pairs (12) have a sawtooth-shaped course. Sensor arrangement after Claim 1 , characterized in that the boundary lines (13) between adjacent pole pairs (12) have an arcuate course. Sensor arrangement after Claim 1 , characterized in that the boundary lines (13) between adjacent pole pairs (12) have a step-shaped course. Sensor arrangement according to one of Claims 1 to 4 , characterized in that the sensor arrangement comprises two magnetic field sensors (14), wherein the magnetic field sensors (14) in the scanning direction (X) out of phase and in the direction perpendicular to the scanning direction (Y) are arranged displaced from each other. Sensor arrangement according to one of Claims 1 to 5 , characterized in that the magnetic field sensor (14) is designed in semiconductor construction and uses a magnetoresistive effect or the Hall effect. Sensor arrangement according to one of Claims 1 to 6 , characterized in that the multipole encoder (10) extends in a flat plane or along a curved surface. Sensor arrangement according to one of Claims 1 to 7 , characterized in that the Multipolencoder (10) is part of a linear bearing or a rotary bearing. Sensor arrangement according to one of Claims 1 to 8th , characterized in that the sensor arrangement can be connected to an evaluation device. Rotational bearing (15) with two relatively rotatable machine parts (17, 18) and a sensor arrangement for detecting the rotational speed, characterized in that the sensor arrangement according to one of Claims 1 to 9 is trained.

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