DE29821513U1 - Device for determining the position of rotating shafts - Google Patents

Description

Applicant: AB Elektronik GmbH Klöcknerstraße D-59368 Werne

Title: Device for determining the position of rotating shafts

30 Representatives: : Patent Attorney

Dr. Helmut Hoffmeister Goldstrasse D-48147 Münster

A:ABG8O_T1.TAT

Device for determining the position of rotating shafts

The invention relates to a device for determining the position of rotating shafts.

From DE 2 95 20 111 Ul a measuring device for contactless detection of a relative movement between a stator and a rotor is known. In this case there is a main air gap between the stator and the rotor and in the

Stator at least one air gap. A magnetically sensitive element is located in at least one air gap. In the rotor at least one ring magnet with magnetic polarization aligned in the radial direction is arranged. A

Ring magnet has an angular range > 180°. This means 25

only the linear range of the characteristic curve is increased from > 90° to approx. +110°.

A rotation angle sensor for determining the position of rotating

Waves are known from WO 92 10 722 Al. On the wave 30

A two-pole, radially magnetized ring magnet is arranged, which is enclosed by a stator. Two opposing air gaps are provided in the stator. A Hall element is arranged in one of the air gaps.

If the ring magnet rotates in the stator, the Hall element only records a Hall voltage curve depending on the position

angle that is similar to a sine curve. When the shaft is rotated by 360°, it is only possible to measure in the linear range of a quadrant, i.e. only from 0° to 90°. The rounded and flattened parts of the Hall clamp curve are unsuitable for measuring purposes. Although the linear range in the first quadrant from 0° to 90° is followed by another in the third quadrant from 180 to 270°, this cannot be used to measure the position within a full rotation due to the rounded and angled parts in between.

From DE 295 20 111 Ul a rotation angle sensor is known, which consists of a stationary and a rotating formation. The stationary formation has two crescent-shaped stator sub-elements which are arranged opposite one another, leaving a spacer recess. The rotating formation is a ring-shaped magnetic element which is held by a magnet holder unit which is connected to a shaft.

The disadvantage is that only one Hall element is arranged in the spacer recess. This means that it is only possible to determine a position of the shaft between 0° and 90°.

Based on a rotation angle sensor with a Hall IC element of the type known from WO 92 10 772 A1, the invention is based on the object of improving the measurement options, in particular in the angle range from 0° to 220°.

According to the invention, this object is achieved by the features of claim 1 or 2.

The advantages achieved with the invention are in particular that two Hall IC voltage curves are measured ₃ g. With this angle sensor it is possible to detect positions of the shaft between 0° and 220° and more and

in order to multiply the measuring possibilities compared to known angle of rotation sensors.

One of the Hall elements can be arranged in each of two adjacent air gaps. This allows a

exact angle between the two Hall EC elements fixed.

A first and a second ring element can be arranged on a shaft. Each ring element can be connected to a stator element.

ment in which a Hall-EC element can be arranged in an air gap. With this solution it is possible to significantly expand the measuring possibilities by using two angle sensors whose Hall-EC elements are arranged offset from one another in the specified angular range.

possibilities to be realized.

This possibility is also given if a first and a second stator element are arranged on another shaft, in each of which a Hall-EC element is located in an air gap

is arranged and each stator element is surrounded by a ring element.

The two Hall IC elements, which are arranged in a stator element, can be connected to an evaluation unit

...
be the

records a Hall IC voltage waveform measured by each Hall IC element,
^: - assigns each recorded flux voltage measurement value to a position angle on the Hall IC voltage curves, and

- - calculates the actual position angle from the position angles assigned to the flux voltage measurement values and outputs it as an output signal.

The evaluation unit working in this way therefore makes it possible to use one Hall IC voltage curve as a measurement curve and the second Hall IC voltage curve as a decision curve.

It also makes it possible to alternately switch each of the Hall IC voltage curves to the linear areas, so that between 0° and 220° you can always work in a straight line curve area. This not only enables a 220° measurement per se, but also a 220° measurement with very high accuracy. The evaluation unit can be designed as a microcomputer or user computer circuit, also known as an ASIC. It should have at least one arithmetic unit (CPU) that is connected to a memory unit. Two analog-digital converters are arranged parallel to one another on the input side of the arithmetic unit. An analog or digital output signal is available on the output side. The analog signal can be provided by a digital-analog converter that is connected to the arithmetic unit on the output side.

If a CAN-BUS interface is connected to the calculator, the digital output signal is available. One of the Hall IC elements is connected to each of the two analog-digital converters. The output signal is available at the digital-analog converter. Instead of a digital calculator,

an analogue calculator can be provided, which can then only be connected to the storage unit. The calculator allows a simple and convenient evaluation of the determined values and an output of the correct angular position of the

Shaft. In a torsion sensor, each angle sensor has a shaft-25

such a unit is arranged. The difference between the different output signals can be used as a measure of the torsion or a torsional moment.

Three air gaps can be inserted in each of the stator elements.

They can be rotated by an angle of 12 0°

' spaced apart from each other. A Hall IC element can be arranged at each of two such adjacent air gaps. The arrangement of the three

Air gap ensures the balance of the entire system. 35

In each stator element, two air gaps spaced at an angle of 180° can also be arranged.

Each ring magnet element can be held by a ring magnet receiving element. The ring magnet receiving element can be held by 5

the shaft. The ring magnet holding element makes it particularly easy to adjust and hold the ring magnet element.

Each stator element can be surrounded by at least one housing.

: ben. In a rotary angle sensor, the housing is also the outer closure of the sensor. Two such housings can be used in one device. Both stator elements can also be surrounded by a common housing.

The invention is illustrated in the drawing and is described in more detail below. They show:

Fig. 1 a 220° rotation angle sensor in a schematic

shown longitudinal section;

Fig. 2a shows a section through a 220° rotation angle sensor according to Fig. 1 along the line UA - HA;

Fig. 2b a section through a 220° rotation angle sensor

according to Fig. 1 along the line HB - HB;

Fig. 3 an evaluation unit for a rotation angle sensor according to Figs. 1, 2a and 2b;

Fig. 4a and 4b show a Hall IC voltage curve of the two Hall ICs as a function of the position angle of ring magnet elements connected to a shaft of two rotation angle sensors according to Fig. 1, 2a and 2b;

·

* I

Fig. 5 shows a section through a first embodiment of a rotation angle sensor;

Fig. 6 a section through a second embodiment

a rotation angle sensor for a 220° rotation angle.

sensor according to Fig. 1, 2a and 2b;

Fig. 7 a section through a third embodiment of a rotation angle sensor and

..

Fig. 8 shows a course of a change of the induction B over

the angle of rotation α of a rotation angle sensor.

A 220° rotation angle sensor is shown in Fig. 1, 2a and 2b.

It consists of two angle of rotation sensors whose ring magnet elements 33, 53 are connected to a shaft 43. The ring magnet element has an enlarged angular range of 180°.

The two rotation angle sensors are also shown in Fig. 6. The ring magnet elements 33, 53 are held by a ring magnet receiving element 33, 53 which are connected to a shaft 43.

Each ring magnet element 33, 53 rotates in a stator element 34, 54, which is surrounded by a housing 40, 60 and closed with a cover 41, 61. A circuit board 44, 64 is positioned in front of the cover. The stator element

can consist either of a magnetically conductive material or of another ring magnet.

There is an air gap 47, 67 between the ring magnet element 33, 53 and the stator element 34, 54.

Two air gaps 35, 55 and 37, 57, spaced apart by an angle of 180°, are introduced into the stator element 34, 54. A Hall-EC element 31, 51 is arranged in the air gap 35, 55. .

As shown in Fig. 2a and 2b, the two Hall EC elements e 31, 51 are arranged offset from each other by an angle. The angle can be between 90 and 280°. In the 220° rotation angle sensor according to Fig. 1, 2a and 2b, the angle is 120°.

The Hall IC elements are conventional Hall measuring elements, each implemented as an integrated circuit. The two Hall IC elements 31, 51 are connected to an evaluation unit 9.

The evaluation unit 9 consists of a computing unit (CPU) 93, which is connected to a memory unit 94. On the input side, an analog-digital converter 91 and an analog-digital converter 92 are arranged on the computing unit 93. The analog-digital

Converter 91 is connected to Hall IC element 1 and analog-digital converter 92 to Hall IC element 2. On the output side, a digital-analog converter 95 is connected to the arithmetic unit 93, which has an analog output signal Al

Alternatively, a CAN-BUS interface 96 can be used to connect a 25

digital output signal A2 can be generated.

This configuration can be implemented either by a universal microcomputer or by an application-integrated integrated circuit (ASIC).

If the ring magnet elements 33, 53 rotate in the stator element 34, 54 as shown in Fig. 2a, 2b, a magnetic flux is emitted according to the following relationship:

B - &Kgr;

with
1

B Magnetic flux
; K device constant

α derivative angle.
5

This magnetic flux is recorded by each Hall IC element 31, 51 as a Hall IC voltage waveform UH1, UH2.

The Hall IC voltage waveform UHl, UH2 as a function of the position angle α is shown in Fig. 4a. Each voltage waveform has a sinusoidal configuration.

The Hall IC voltage curve UHl has a linear curve in the first quadrant I and partly in the second quadrant II, which ranges from 0° to 110°, followed by a curved and then straight curve in the second quadrant II and in the third quadrant III from 110° to 160°. The next straight curve is in the third quadrant III from 160° to 210°, followed by another curved curve in the fourth quadrant IV from 270° to 360°.

The Hall IC voltage curve UH2 is offset by 120° from the Hall IC voltage curve UH1, i.e. the first linear part in the second quadrant II and in the third quadrant III, followed by a curved and straight part in the fourth quadrant IV. Fig. 4a clearly shows the advantages of the Hall IC elements 31, 51 arranged at 120° to each other, because there is a linear area in each quadrant that enables precise measurement of the angular position.

These two Hall IC voltage curves UHl, UH2 are entered into the evaluation unit 9 and stored in the memory unit 94'. The memory unit 94 also contains the operating program of the evaluation unit, which runs as follows:

A) Recording of the Hall IC voltage curve UHl, UH2 measured by each Hall IC element 1, 2.

B) Assignment of each recorded flux voltage measurement value as a position angle on the Hall IC voltage curves.

C) Calculating the actual position angles from the position angles assigned to the flux voltage measurement values and outputting an output signal A.

The program makes it clear that one of the Hall IC voltage curves UHl, UH2 is both a measurement curve and a decision curve, and that when one of the Hall IC voltage curves UHl, UH2 is defined as a measurement curve, the decision curve is used to determine which of the flux voltage measurement values determined are to be assigned to a specific angle. The assignment can be made in tabular form in the storage unit 94.

The work of this program is explained using some example flux-voltage measurements:

In a first measurement, a flux voltage value UHlMl is measured. This measured value corresponds to an angle of 120° or 250° on the Hall IC voltage curve UHl. When the ring magnet element 53 is positioned in the stator element 54,

from the second Hall IC element 51 a flux voltage measurement value of 25

UH2M1, to which an angle of 95° is to be assigned. The evaluation unit 9 now decides that the Hall IC voltage curve UH2 is the decision curve and the Hall IC voltage curve UHl is the measurement curve. The program states that at a position angle αΜ2Μ1 at 120° the actual output

angle al and provides a corresponding output signal Al, A2.

The Hall IC element 1 measures a flux voltage value UH1M2 of 4.3 volts. The angles 150° and 240° are assigned to this value as αΜ1Μ2. The second Hall IC element 51 measures a flux voltage value UH2M2 of 1 volt.

■ &iacgr;&ogr;

to which both an angle of 120° and 330° can be assigned. The logic in the form of the evaluation unit 9 decides on the basis of the program that the Hall IC voltage curve UH1 is the decision curve and the Hall IC voltage curve UH2 is the measurement curve. The program states that with these values of the flux voltage measurement value UHM2 of 1 volt, the position angle aH2M2 is to be output as the actual position angle ai2 .

The two examples clearly show the great advantage of the Hall IC elements arranged offset by 120°. What is important is that the addition of a Hall IC element practically quadruples the measuring capability of a rotation angle sensor compared to the state of the art.

The decision as to which curve is the measurement curve and which curve is the decision curve and which measured value is output can be made in the form of a table which, as already mentioned, is stored in the memory unit. The computer compares the individual values and then, with the help of

the program would make the appropriate decisions.

Instead of a table, the slope can be used to determine which curve is the measurement curve and which curve is the decision curve. The slope also determines which of the

measured values are output. Tests have shown that the tabular form of the evaluation is more accurate.

The course of the change of induction B over the angle of rotation

α of the angle of rotation sensors used, as shown in Fig. 4a, has a linear measuring range of approx. +110° compared to the conventional 90° sensors of ± 75°. With the angle of rotation sensors used, the range of highest

Measurement accuracy, namely at B = 0, in the middle of the measurement range. 35

This makes it possible to use the range of the highest measurement accuracy at B=0 of the two Hal-EC elements 31, 51 shifted against each other, as shown in Fig. 4b. Shifting the two Hal-EC voltage curves UHl, UH2 against each other thus makes it possible to

to achieve a straight measuring range of 2x 110° = 220° with just one switch. Such a 220° angle of rotation sensor can always be used when no angles between 220 and 380° need to be measured.

Instead of two angle of rotation sensors, each with a Hall EC element, one angle of rotation sensor can also be used which has three air gaps which are offset from one another by 120°, with the Hall EC elements 31, 51 being arranged in two adjacent air gaps.

This would result in a configuration similar to that in Fig. 7. However, the angle of rotation sensor shown in Fig. 7 also has two air gaps 25, 28 that are offset by 120° from each other. The air gaps 25, 28 are incorporated in a stator element 24. In the stator element

24 there is a ring magnet element 23 which has an angular range of > 180°. The ring magnet element 23 is connected to the shaft. There is an air gap 27 between the ring magnet element and the stator element.

The one shown in Fig. 5 differs from the previously described angle of rotation sensors shown in Fig. 1, 2a, 2b, 6 and 7. Here, a stator element 4 can be connected to a shaft into which two air gaps 5, 6 are introduced, which are arranged offset by 180° from one another. In the

A Hall EC element 2 is arranged in the air gap 6.

In order to be able to generate a measuring signal using the Hall EC element 2, a first ring magnet 7 and a second ring magnet 8 are embedded in the inner wall of a rotor 3 facing the stator 4. The ring magnet 7 forms an angular segment of approximately 240°, while the second ring magnet 8 forms a

angular segment of 120°, so that the two ring magnets 7, 8 form a closed circle. The ring magnet 7 has an angular range of > 180° and the second ring magnet 8 has an angular range that supplements the angle of 360°. The magnetic polarization of the two 5

Ring magnets 7, 8 are aligned radially and in opposite directions, so that the magnetic north pole of the ring magnet 7 is located on the inner wall of the rotor 3, while the magnetic south pole of the second ring magnet 8 is located on the inner wall

of the rotor 3 (cf. DE 295 20 111 Ul). The course 10

the magnetic field line of the magnetic flux is in

Fig. 5. If the rotor 3 moves relative to the stator 4, the magnetic flux through the Hall element 6 increases or decreases depending on the direction of rotation. The change in the strength of the magnetic flux is linear to the angle of rotation of the rotor 15.

3 relative to the stator 4. The magnetic induction B generates an electrical output signal in the Hall element that is linear to the angle of rotation, as shown in Fig. 8.

Claims (9)

■ . - Al (ABG80 Al) Protection claims: 1. Device for determining the position of rotating shafts with : - at least one ring magnet element (23; 33; 53), ¹ ^ .which has an angular range of greater than 180° and . which is connected to the shaft (43), and - at least one stator element (24; 44; 64) made of a magnetically conductive material, . in which the ring magnet element (23; 33; 53) is arranged and . in which at least two air gaps (25, 28; 35, 37; 55, 57) are provided offset by the same angle, . wherein a Hall IC element (21, 22; 31; 51) is arranged, - wherein a first and a second Hall IC element (21, 22; 31; 52) are provided, - wherein the first Hall IC element (21; 31) is arranged offset from the second Hall IC element (22; 52) by an angle ( ) between 90° and 280°, - wherein the two Hall IC elements (21, 31; 22, 52) are connected to an evaluation unit (9) which : records a Hall IC voltage curve (UHl, UH2) measured by each Hall IC element (21, 31; 22, 52), assigns each recorded flux voltage measurement value (UHlMl, UH2M1; UH1M2, UH2M2) to a position angle (aHlMl, α&EEgr;2�M1;α&EEgr;1�M2, aH2M2) on the Hall IC voltage curves (UHl, UH2), and
from the position angles (aHlMl, α&EEgr;2&Mgr;1;) assigned to the flux-voltage measured values (UHlMl, UH2M1; UH1M2, UH2M2). A2 &agr;&EEgr;1&Mgr;2, &agr;&EEgr;2&Mgr;2) calculates the actual position angle (al; a2) and outputs it as an output signal (Al, A2). 2. Device for determining the position of rotating Waves with
5 - at least one ring magnet element (3) . which has an angular range greater than 180°, and - at least one stator element (4) made of a magnetically conductive material, . in which, offset by an equal angle, at least two air gaps (5, 6) are introduced, wherein in a Hall IC element (2) is arranged in an air gap (5, 6),
'.' . which is arranged in the ring magnet element (3) and . which is connected to the shaft (43) - wherein a first and a second Hall IC element (2) are provided, - wherein the first Hall IC element (2) is offset from the second Hall IC element by an angle between 90° and 280°, - wherein the two Hall IC elements (2) are connected to a Evaluation unit (9) which records a Hall IC voltage curve (UHl, UH2) measured by each Hall IC element (2), each recorded flux voltage value (UHlMl, UH2ml; UH1M2, UH2M2) to a Position angle (HlMl, H2M1; H1M2, H2M2) to the Hall IC voltage curves (UHl, UH2), and from the position angles (HlMl, H2M1; H1M2, H2M2) assigned to the flux voltage measurement values (UHlMl, UH2M1; UH1M2, UH2M2) the actual position angle (1; 2) is calculated. 3. Device according to claim 1 or 2, characterized in that one of the Hall IC elements (21, 22) is arranged in each of two adjacent air gaps (21, 22). A3 4. Device according to claim 1, characterized in - that a first and a second ring magnet element (33, 53) are arranged on a shaft (43) and - that each ring magnet element (33, 53) is surrounded by a stator element (34, 54) in which a Hal-IC element (31, 52) is arranged in an air gap (36, 37, 38, 55, 56, 57, 58), 5. Device according to claim 2, characterized in - that a first and a second stator element (4) are arranged on a further shaft, in each of which a Hall IC element (2) is arranged in an air gap (5, 6), and - that each stator element (4) is surrounded by a ring magnet element (3) is surrounded
15 6. Device according to one of claims 1 to 5, characterized in that the evaluation unit (9) is designed as a microcomputer or user computer circuit (ASIC) and has at least - a central processing unit (CPU) (93), . which is connected to a storage unit (94), . to which a first and a second analog-digital converter (91, 92), each of which is connected to one of the Hall IC elements (2; 25 31, 37; 51, 57) and . at which a digital or analog output signal (Al, A2) is present on the output side. 7. Device according to one of claims 1 to 6, characterized in characterized in that four air gaps (35, 36, 37, 38, 55, 56, 57, 58) arranged at an angle of 90° to one another are introduced into each of the stator elements (34, 54). 8. Device according to one of claims 1 to 7, that each Ring magnet element (33, 53) from a ring magnet receiving A4 element (45, 65) which is connected to the shaft (43). 9. Device according to one of claims 1 to 8, characterized in that a stator element (34, 54) is arranged in at least one housing (40, 60).