DE102019120790A1 - Sensor arrangement with multipole encoder and rotation bearing - Google Patents

Abstract

The present invention relates to a sensor arrangement for determining a path or an angle of rotation or also a speed or an angular speed. The sensor arrangement comprises a multipole encoder made up of several adjacent magnetic pole pairs (01), which provide a scanning plane with magnetic north poles (02) and south poles (03) arranged alternately in a scanning direction (x), each of which is separated from one another by a boundary line (04) . The sensor arrangement further comprises at least one magnetic field sensor which is movable in the scanning direction (x) relative to the magnetic field sensor, a duty cycle of a signal of the magnetic field sensor corresponding to a ratio of a width of one of the north poles (02) to a total width of one of the pole pairs (01). The boundary lines (04) are designed in such a way that when the multipole encoder moves in the scanning direction (x) and when it moves at the same time in a direction perpendicular to it (y), the pulse duty factor of the signal changes according to a non-linear function depending on the simultaneous movement of the Multipole encoder in the vertical direction (y) changes. According to the invention, the non-linear function at a nominal position (06) of the multipole encoder in relation to the magnetic field sensor in the vertical direction (y) has an extreme of its slope. The invention also relates to a rotary bearing with two machine parts that can be rotated relative to one another and a sensor arrangement for detecting a rotational speed.

Description

The present invention relates to a sensor arrangement for determining a path or an angle of rotation or also a speed or an angular speed. The sensor arrangement comprises a multipole encoder made up of several mutually adjacent magnetic pole pairs and a magnetic field sensor. The invention also relates to a rotary bearing with two machine parts that can be rotated relative to one another and with a sensor arrangement for detecting a rotation speed.

The EP 1 749 193 B1 shows a rolling bearing unit with a load measuring unit. The rolling bearing unit comprises a stationary-side raceway ring, a rotating-side raceway ring and a plurality of rolling elements. The load measuring unit comprises an encoder, which is held on part of the rotating-side raceway ring concentrically with the rotating-side raceway ring and which has a detected surface with a property that changes alternately along a circumferential direction, in particular changing magnetization. The magnetized areas have widths that vary depending on the diameter, in order to be able to determine not only a speed but also a displacement of the encoder and thus a roller bearing load. A sensor is held on a non-rotated part in a state in which a detection part is opposed to the detected surface.

From the DE 10 2007 023 385 A1 a measuring device for the contactless detection of linear or rotational movements is known, which works with a stationary magnetoresistive chip sensor and a magnetic field transmitter device adjacent to this, leaving an air gap free. The magnetic field transmitter device has individual magnet segments whose polarity is alternately magnetized in the z direction of a three-dimensional x / y / z coordinate system. The chip sensor is aligned with its large areas in the x / y plane or in the x / z plane of the coordinate system or in an intermediate position to these planes. The measuring direction and the large area of the chip sensor are each in the x direction of the x / y / z coordinate system.

The EP 1 876 422 A1 teaches an apparatus for the acquisition and transmission of angular information. The device comprises a rotatable encoder wheel to which signaling elements are assigned. The signals sent out by the elements can be detected by a sensor in order to determine an angle of rotation and / or an angular speed of the encoder wheel. The elements have signal-emitting means, by means of which a translational movement superimposed on the rotating movement of the transmitter wheel can be detected by the sensor.

The US 2004/0263159 A1 shows a device for determining the movement of a drive shaft. This device comprises a multi-pole magnet and a sensor. The sensor or magnet is rotated by the drive shaft. The magnet has north and south poles, which alternate according to the relative angular position of the sensor and the magnet. The poles are made of a magnetizable material. The movement of the drive shaft along the axis can be recognized according to the recognized polarity reversal.

From the JP 2007-051962 A a device is known with which a load acting between a housing washer and a roller bearing unit can be determined. The device comprises a sensor and an encoder with alternating magnetic north and south poles. A change in an output signal of the sensor is measured in relation to a surface of the transmitter to be detected. Boundaries between the magnetic north and south poles on the surface of the encoder to be detected are formed in a curved shape.

The DE 10 2018 106 438 A1 shows a sensor arrangement with a multipole encoder made up of several adjacent pairs of poles which provide a scanning plane with magnetic north and south poles arranged alternately in a scanning direction X, and with at least one magnetic field sensor with a sensor surface. The multipole encoder can be moved in the scanning direction X relative to the magnetic field sensor, so that a magnetic field with alternating polarity that is variable in the scanning direction runs through the sensor surface, the scanning field strength of which shows a zero crossing between adjacent poles. The sensor arrangement is characterized in that the boundary lines between adjacent pole pairs of the multipole encoder are designed in such a way that the pulse duty factor of the signal of the magnetic field sensor changes when the multipole encoder is moved in the scanning direction X if, at the same time, the multipole encoder is moving in a direction perpendicular to the scanning direction Y takes place while the total width of the pole pair with the north pole and south pole remains the same, the duty cycle corresponding to the ratio of the north pole width to the total width of the pole pair with north pole and south pole. With this solution and also with those in the EP 1 749 193 B1 , the JP 2007-051962 A and the US 2004/0263159 A1 Although the solutions shown, it is possible to detect movements of the multipole encoder perpendicular to the scanning direction, but only imprecisely, which is not the case for many applications, in particular for bearing applications with a high degree of rigidity is sufficient, since operational bearing loads only lead to very small displacements between a movable and a stationary bearing part.

Based on the prior art, the object of the present invention is to provide an improved sensor arrangement which uses a multipole encoder with a scanning plane of several magnetic poles following one another in a scanning direction and detection of movements in the scanning direction and, in addition, more sensitive detection of movements of the multipole encoder perpendicular to the scanning direction. In this way, a load on a bearing can be determined indirectly, with increased sensitivity being made possible at the same time.

The stated object is achieved by a sensor arrangement according to the attached claim 1 and by a rotary bearing according to the attached independent claim 10.

The sensor arrangement according to the invention is used to determine a path or an angle of rotation or also a speed or an angular speed in a main direction of movement, which as a rule represents an x-direction. Furthermore, it is also possible to detect a displacement in a direction perpendicular to the main direction of movement, in particular in a y-direction. The sensor arrangement comprises a multipole encoder made up of a plurality of mutually adjacent magnetic pole pairs which provide a scanning plane with magnetic north poles and south poles arranged alternately in a scanning direction. The pole pairs each have the same overall width, the overall width including the respective north pole and the respective south pole. The successive poles are provided by the lined-up pairs of poles, the poles having alternating magnetic field orientations. The north and south poles are separated from each other by a boundary line. The polarization changes at the border lines. The multipole encoder forms a primary sensor of the sensor arrangement.

The sensor arrangement further comprises at least one magnetic field sensor with a sensor surface. The multipole encoder can be moved in the scanning direction relative to the magnetic field sensor, so that a variable magnetic field with alternating polarity runs through the sensor surface. A signal generated by the magnetic field sensor thereupon has a sinusoidal or a sinusoidal curve which reflects the alternating polarity of the multipole encoder. The variable magnetic field running through the sensor surface has a scanning field strength which shows a zero crossing in relation to the north and south poles. With a constant speed of movement in the scanning direction, the period of this sinusoidal or sinusoidal signal is also constant. The width of a positive sine half-wave of this signal, which is generated, for example, when passing through one of the magnetic north poles, and the width of a negative sine half-wave of this signal, which is generated, for example, when passing through one of the magnetic south poles, are then equal. A duty cycle is the ratio of a variable width of one of the north poles to a total width of one of the pole pairs or the equivalent durations in the sinusoidal signal of the magnetic field sensor and is in a regular case, i.e. H. without shifting the multipole encoder in the direction perpendicular to the scanning direction, 0.5 or 50%. The magnetic field sensor forms a secondary sensor of the sensor arrangement.

The boundary lines between neighboring north and south poles or the south and north poles of the multipole encoder are designed such that the duty cycle changes when the multipole encoder moves in the scanning direction and when the multipole encoder moves at the same time in a direction perpendicular to the scanning direction of the signal of the magnetic field sensor changes according to a non-linear function as a function of the simultaneous movement of the multipole encoder in the direction perpendicular to the scanning direction. The direction running perpendicular to the scanning direction lies in the plane of the boundary lines, which preferably also forms a main plane of extent of the multipole encoder and preferably also the scanning plane. Due to the course of the boundary lines, the width of the north poles and the width of the south poles change in the direction perpendicular to the scanning direction, which also leads to a corresponding change in the duty cycle. According to the invention, the nonlinear function has an extreme of its slope at a nominal position of the multipole encoder in the direction running perpendicular to the scanning direction. The nominal position of the multipole encoder in the direction perpendicular to the scanning direction is related to the magnetic field sensor and preferably represents a central position. At this nominal position of the multipole encoder, the coordinate in the direction perpendicular to the scanning direction is zero. The extreme of the slope is formed by a maximum of the slope or a minimum of the slope. The extreme of the slope of the nonlinear function preferably represents a point of inflection of the nonlinear function at which the second derivative of the nonlinear function is equal to zero. In this sense, the displacement of the multipole encoder in the direction perpendicular to the scanning direction forms the abscissa and the scanning direction forms the ordinate.

A significant advantage of the sensor arrangement according to the invention is that, due to the special design of the boundary lines between adjacent north and south poles of the multipole encoder, in addition to the movements aligned in the scanning direction, movements perpendicular to the scanning direction can also be precisely detected. For this purpose, the duty cycle is evaluated. Even a slight relative movement between the magnetic field sensor and the multipole encoder perpendicular to the scanning direction, i.e. a small deviation from the nominal position of the multipole encoder, leads to a relatively large change in the duty cycle, since the non-linear function describing the boundary lines is introduced at the nominal position of the multipole encoder Has extremum of their slope. Even the smallest relative movements between the magnetic field sensor and the multipole encoder can thus be detected perpendicular to the scanning direction. Starting from the nominal position, the width of magnetic areas of the individual north and south poles varies non-linearly in the direction of the outer edges of the multipole encoder differently between the north and south poles, so that zero crossings in the signal of the magnetic field sensor are shifted relative to one another when a relative shift occurs between the Sets the multipole encoder and the magnetic field sensor perpendicular to the scanning direction.

In preferred embodiments of the sensor arrangement according to the invention, the nonlinear function is symmetrical, in particular point symmetrical, with respect to the nominal position in the direction running perpendicular to the scanning direction. The pulse duty factor thus changes to the same absolute extent as a function of the deviation from the nominal position of the multipole encoder in the direction perpendicular to the scanning direction, regardless of whether the deviation occurs in a positive or negative direction, i.e. H. regardless of whether the deviation is positive or negative.

In preferred embodiments of the sensor arrangement according to the invention, the pulse duty factor changes as a function of a sense of direction of the deviation from the nominal position of the multipole encoder in the direction perpendicular to the scanning direction. If this sense of direction is positive, the pulse duty factor preferably rises above 0.5. If this sense of direction is negative, the pulse duty factor preferably falls below 0.5.

In preferred embodiments of the sensor arrangement according to the invention, an absolute amount of the slope of the nonlinear function decreases steadily with a distance from the nominal position of the multipole encoder in the direction perpendicular to the scanning direction. Thus, the non-linear function has no steps or edges or the like. The nonlinear function is preferably continuous and also preferably monotonic.

In preferred embodiments of the sensor arrangement according to the invention, the extreme of the slope of the nonlinear function at the nominal position of the multipole encoder in relation to the magnetic field sensor in the direction perpendicular to the scanning direction has an absolute amount which is at least 2 and more preferably at least 10. The slope thus has a value greater than or equal to 2 or less than or equal to -2 or greater than or equal to 10 or less or equal to -10.

In preferred embodiments of the sensor arrangement according to the invention, the slope of the nonlinear function at a distant position of the multipole encoder with respect to the magnetic field sensor in the direction perpendicular to the scanning direction has an absolute amount which is at most 0.5 and more preferably at most 0.1. The remote position of the multipole encoder in relation to the magnetic field sensor is at a distance from the nominal position in the direction perpendicular to the scanning direction which corresponds to a quarter of the width of the multipole encoder in the direction perpendicular to the scanning direction.

The nonlinear function can also be approximated from a technical point of view; for example by a large number of linear sections which in their totality represent an approximated non-linear function.

The at least one magnetic field sensor is preferably designed to measure a single directional component of the magnetic field of the multipole encoder, so that the sensitivity of the magnetic field sensor is pronounced in a single direction.

A main direction of magnetization of the multipole encoder and the direction of the sensitivity of the magnetic field sensor are preferably aligned in the same way.

The main direction of magnetization of the multipole encoder and the direction of the sensitivity of the magnetic field sensor are preferably aligned perpendicular to the scanning direction and perpendicular to the main plane of extension of the multipole encoder.

In a further preferred embodiment, the main direction of magnetization of the multipole encoder and the direction of sensitivity of the magnetic field sensor are aligned in the scanning direction.

Preferred embodiments of the sensor arrangement according to the invention include two of the magnetic field sensors. The magnetic field sensors are arranged out of phase with one another in the scanning direction. In addition, the magnetic field sensors are arranged shifted to one another in the direction running perpendicular to the scanning direction. This enables a clear measurement to be made in the scanning direction. In the case of a standstill in the scanning direction and a movement in the direction perpendicular to the scanning direction, a conclusion can be drawn about the position.

The sensor arrangement according to the invention is not limited to a specific principle of magnetic field measurement by the at least one magnetic field sensor. The at least one magnetic field sensor is preferably designed such that it uses the magnetoresistive effect or the Hall effect to measure a directional component of a magnetic field of the multipole encoder. Different principles of magnetic field measurement can also be combined. In any case, the direction of sensitivity of the magnetic field sensor and the main direction of magnetization of the multipole encoder are preferably aligned in the same way.

The multipole encoder is preferably designed as part of a linear bearing or a rotary bearing.

The multipole encoder can extend both in a flat surface and along a curved surface. The multipole encoder preferably has the shape of a rectangle or a strip if the sensor arrangement is designed to measure a linear path or a linear speed. The multipole encoder preferably has the shape of a circular ring or a cylinder jacket if the sensor arrangement is designed to measure an angle or an angular velocity.

According to an advantageous embodiment, the sensor arrangement can be connected to an evaluation device. In this context, it has proven to be expedient to equip the sensor device with a connection 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 with a radio signal.

The rotary bearing according to the invention comprises two machine parts that can be rotated relative to one another and the sensor arrangement described above, which is used to detect a rotational speed occurring between the machine parts. The machine parts that can rotate relative to one another are preferably formed by an outer ring and an inner ring of the rotary bearing. The rotary bearing can be designed, for example, as a wheel bearing. The rotary bearing preferably comprises one of the described preferred embodiments of the sensor arrangement according to the invention.

• 1 eine schematische Darstellung eines Multipolencoders einer bevorzugten Ausführungsform einer erfindungsgemäßen Sensoranordnung;
• 2 eine schematische Darstellung eines Multipolencoders einer Sensoranordnung gemäß dem Stand der Technik;
• 3 ein Diagramm eines Verlaufes eines Ausgangssignales der in 1 gezeigten Sensoranordnung; und
• 4 ein Diagramm eines Verlaufes eines Ausgangssignales der in 2 gezeigten Sensoranordnung.

Further details, advantages and developments of the invention emerge from the following description of a preferred embodiment of the invention in comparison to the prior art, with reference to the drawing. Show it:

• 1 a schematic representation of a multipole encoder of a preferred embodiment of a sensor arrangement according to the invention;
• 2 a schematic representation of a multipole encoder of a sensor arrangement according to the prior art;
• 3 a diagram of a course of an output signal in 1 sensor arrangement shown; and
• 4th a diagram of a course of an output signal in 2 sensor arrangement shown.

1 shows a schematic representation of a multipole encoder of a preferred embodiment of a sensor arrangement according to the invention. The multipole encoder has a large number of magnetic pole pairs 01 on, each having a magnetic north pole 02 and a magnetic south pole 03 include which in a scanning direction x are arranged alternately. The magnetic north and south poles 02 , 03 are each through a boundary line 04 separated from each other. The border lines 04 run in a direction perpendicular to the scanning direction x aligned direction y non-linear. At a middle nominal position 06 , in which a coordinate in the direction y equals zero, indicate the boundary line 04 each has an extreme of its slope. The greater the distance from the middle nominal position 06 in the direction y becomes, the smaller the slope of the boundary lines becomes 04 .

The sensor arrangement according to the invention further comprises a magnetic field sensor (not shown) which is arranged opposite the multipole encoder.

The non-linear course of the boundary lines 04 determines a pulse duty factor of a scanning field strength to be measured by the magnetic field sensor (not shown) when the multipole encoder is in the direction y emotional. This assumes that the multipole encoder is also in the direction x emotional.

2 shows a schematic representation of a multipole encoder of a sensor arrangement according to the prior art, as it is from FIG DE 10 2018 106 438 A1 , from the EP 1 749 193 B1 , from the JP 2007-051962 A and from the US 2004/0263159 A1 is known. Like the one in 1 Multi-pole encoder shown has a large number of magnetic pole pairs 01 on, each having a magnetic north pole 02 and a magnetic south pole 03 include which in a scanning direction x are arranged alternately. The magnetic north and south poles 02 , 03 are each through a boundary line 04 separated from each other, whereby in contrast to the in 1 Multipole encoder shown the boundary lines 04 run linearly.

3 shows a diagram of a profile of an output signal of the 1 sensor arrangement according to the invention shown. In a first case, the multipole encoder is in the nominal position with respect to the magnetic field sensor (not shown) 06 . In this first case, the output signal shows a first profile 08 with extremes 09 and zeroing 11 . The first course 08 corresponds to an unchanged sinusoidal signal, so that the times between the zeros 11 have a ratio of one. This ratio determines a duty cycle, which is 0.5 here. In a second case, the multipole encoder is located in the direction related to the magnetic field sensor (not shown) y in a slightly different position 12 . In this second case, the output signal shows a second profile 13 with the extremes 09 and the zeros 11 . Despite the very small deviation of the slightly different position 12 from the nominal position 06 is the sinusoidal second curve 13 significantly changed compared to the first curve, so the times between the zeros 11 soften a ratio to one another which deviates significantly from one, so that the pulse duty factor deviates significantly from 0.5, which is easily measurable.

4th shows a diagram of a profile of an output signal of the 2 shown sensor arrangement according to the prior art. As with the representation in 3 the output signal is shown for the first case in which the multipole encoder is at the nominal position in relation to the magnetic field sensor (not shown) 06 is located. In this first case, the output signal shows a third curve 16 with the extremes 09 and the zeros 11 . The third course 16 resembles the first course 08 (shown in 3 ) and therefore again corresponds to an unchanged sinusoidal signal, so that the times between the zeros 11 have a ratio of one and the duty cycle is 0.5. In a third case, the multipole encoder is located in the direction of the magnetic field sensor (not shown) y in a clearly different position 17th , which is a significantly larger distance from the nominal position 06 than the slightly different position 12 owns. In this third case, the output signal shows a fourth profile 18th with the extremes 09 and the zeros 11 . Despite the large deviation of the clearly different position 17th from the nominal position 06 is the sinusoidal fourth curve 18th only changed as much as the second course 13 (shown in 3 ). The slightly different position would be accordingly 12 in the sensor arrangement according to the prior art only lead to a slight change in the sinusoidal curve and thus to a smaller change in the pulse duty factor, which would be disadvantageous for the metrological implementation.

List of reference symbols

01

Pole pair

02

North Pole

03

South Pole

04

Boundary line

05

-

06

nominal position

07

-

08

first course

09

Extremum

10

-

11

Zero

12

slightly different position

13

second course

14th

-

15th

-

16

third course

17th

clearly different position

18th

fourth course

x

Scan direction

y

direction perpendicular to the scanning direction

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• EP 1749193 B1 [0002, 0007, 0034]
• DE 102007023385 A1 [0003]
• EP 1876422 A1 [0004]
• US 2004/0263159 A1 [0005, 0007, 0034]
• JP 2007051962 A [0006, 0007, 0034]
• DE 102018106438 A1 [0007, 0034]

Claims (10)

A sensor arrangement comprising: - a multipole encoder made up of several mutually adjacent pairs of poles (01) which provide a scanning plane with magnetic north poles (02) and south poles (03) arranged alternately in a scanning direction (x), the pole pairs (01) each having the same overall width and wherein the north poles (02) and the south poles (03) are each separated from one another by a boundary line (04); and - at least one magnetic field sensor with a sensor surface, the multipole encoder being movable in the scanning direction (x) relative to the magnetic field sensor so that a variable magnetic field with alternating polarity runs through the sensor surface, the scanning field strength of which in relation to the north and south poles ( 02, 03) each shows a zero crossing (11), a duty cycle of a signal from the magnetic field sensor corresponding to a ratio of a width of one of the north poles (02) to the total width of one of the pole pairs (01); wherein the boundary lines (04) between the adjacent north and south poles (02, 03) of the multipole encoder are formed in such a way that when the multipole encoder is moved in the scanning direction (x) and when the multipole encoder is moved at the same time in a perpendicular to the Scanning direction (x) direction (y) changes the duty cycle of the signal of the magnetic field sensor according to a non-linear function depending on the simultaneous movement of the multipole encoder in the direction (y) perpendicular to the scanning direction (x), characterized in that the non-linear function a nominal position (06) of the multipole encoder with respect to the magnetic field sensor in the direction (y) perpendicular to the scanning direction (x) has an extreme of its slope. Sensor arrangement according to Claim 1 , characterized in that the non-linear function with respect to the nominal position (06) runs point-symmetrically in the direction (y) running perpendicular to the scanning direction (x). Sensor arrangement according to Claim 1 or 2 , characterized in that an absolute amount of the slope of the nonlinear function decreases continuously with a distance from the nominal position (06) in the direction (y) running perpendicular to the scanning direction (x). Sensor arrangement according to one of the Claims 1 to 3 , characterized in that the extreme of the slope of the nonlinear function at the nominal position (06) of the multipole encoder in relation to the magnetic field sensor in the direction (y) perpendicular to the scanning direction (x) has an absolute amount which is at least two. Sensor arrangement according to one of the Claims 1 to 4th , characterized in that the slope of the nonlinear function at a remote position of the multipole encoder in relation to the magnetic field sensor in the direction (y) perpendicular to the scanning direction (x) has an absolute amount which is at most 0.5, the remote position of the Multipole encoder has a distance to the nominal position (06) in the direction (y) perpendicular to the scanning direction (x), which corresponds to a quarter of the width of the multipole encoder in the direction (y) perpendicular to the scanning direction (x) . Sensor arrangement according to one of the Claims 1 to 5 , characterized in that it comprises two of the magnetic field sensors, the magnetic field sensors being arranged out of phase in the scanning direction (x) and displaced from one another in the direction (y) running perpendicular to the scanning direction (x). Sensor arrangement according to one of the Claims 1 to 6 , characterized in that the at least one magnetic field sensor is designed to use the magnetoresistive effect or the Hall effect to measure a directional component of a magnetic field of the multipole encoder. Sensor arrangement according to one of the Claims 1 to 7th , characterized in that the multipole encoder extends in a flat surface (x, y) and has the shape of a strip or a circular ring, or that the multipole encoder extends in a curved surface and has the shape of a cylinder jacket. Sensor arrangement according to one of the Claims 1 to 8th , characterized in that the multipole encoder forms part of a linear bearing or a rotary bearing. Rotary bearing with two machine parts rotatable relative to one another and with a sensor arrangement for detecting a rotational speed, characterized in that the sensor arrangement according to one of the Claims 1 to 9 is trained.

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