DE10236889A1 - High-resolution rotation angle sensor for detecting the impulses of an impulse generator, fixed to a rotor, has a number of fixed sensor elements, with the total number of sensor elements equal to four or a multiple of four - Google Patents

Abstract

High-resolution rotation angle sensor for a rotor (20) that has an impulse generator fixed to it. The impulses of the generator are detected by a number of fixed sensors (S1-S16) that detect the generator signal pulse. Each impulse of the impulse generator has a defined length, (36) so that each impulse is detected by a number of sensors. The total number of sensors is four or a multiple of four.

Description

The invention relates to a high resolving angle of rotation sensor for one Rotor, with a pulse generator connected to the rotor in a rotationally fixed manner and several stationary sensors that interact with the pulse generator, wherein each pulse of the pulse generator has a certain pulse length and several sensors are assigned to each pulse.

Such rotation angle sensors are generally known and used to determine a rotational angle position, to detect the rotational speed or an angular acceleration. In particular Such rotation angle sensors are used in industrial engines and in the automotive sector used.

Optical systems are known which a light-emitting diode (LED) and optical transistors or light-sensitive Have elements, as well as with panels and a transparent disc are provided with a barcode. Such a system works very accurate and has a large one Dissolution, however the lifespan of LEDs is usually short. The maximal Operating temperature is 85 ° C and the system is sensitive to impact. The system is therefore not Suitable for use in vehicles where the operating temperature is above 150 ° C can and where the system is exposed to accelerations of 30g is.

Furthermore, resolvers are known which have a special motor, called resolver, and with a Signal evaluation circuit are provided. The output signals of this Resolvers are two-phase analog signals, the amplitude of one Sine / cosine function that follows the angle between the rotor and represents the stator. The aim of the signal evaluation circuit is the analog sine / cosine signal into a digital angle signal reshape. Such a system is highly precise and can also work under adverse conditions Conditions are used. However, the size is one such system for many applications too large, especially if only limited installation space is available. Furthermore, the cost of such a system is and will be very high usually for the civilian use not accepted.

Magnetic pulse generators are also known which have a magnetic ring, a sensor and a signal evaluation circuit exhibit. The magnetic ring usually has several pole pairs, the same pole lengths exhibit. The system can also operate under adverse environmental conditions be used because it is resistant to high temperatures, against impact and insensitive to pollution. Moreover this system has a long service life and is very reliable. The Disadvantage of this system is that the space on the magnetic ring only for one limited number of pole pairs is sufficient so that the maximum resolution the angular position is low.

From the US 4,369,405 a device for detecting the rotational position of a disc is known. The circumference of the disk is provided with magnetic poles and these magnetic poles are opposed by stationary sensors which are equipped with two magneto-sensitive elements. The resolution of such an arrangement is very low. From the US 4,599,561 is known device for detecting the relative and absolute position of a moving object. For this purpose, a disk is used which has a large number of pole pairs in the circumferential direction and in the radial direction, as a result of which the resolution is to be increased. The construction of this device is very complicated and requires a lot of space. From the US 5,089,060 and the US 5,283,130 a magnetic ring is known, over the circumference of which magnetic poles are distributed. These magnetic poles are assigned sensors which are arranged next to one another in the axial direction. The resolution cannot be increased with such an arrangement. From the US 5,568,048 a magnetic ring with a multiplicity of pole pairs is known, to which three sensors are assigned which lie next to one another in the circumferential direction. The two outer sensors are always opposite two poles next to each other. The resolution of such an arrangement is low.

The invention is therefore the object to provide a rotation angle sensor that is high-resolution, which can also be used under adverse operating conditions, which has a small installation space and a long service life and which is also inexpensive.

This task is done with a rotation angle sensor of the type mentioned in the invention solved in that the number of sensors is X = 4N, where N> 1.

The main idea of the invention is in the dissolution of the system, i.e. the number of pulses delivered by the system per revolution of the magnetic pulse generator, by one or more Increase groups of 4 sensors each. Become multiple sensors used, then can the output signals of these sensors are advantageously interconnected that thereby a higher resolution can be generated.

The sensors preferably have one Angular distance of 45 ° / N on. This means that over the Scope at least four sensors are arranged, the rotational position of the rotor.

The sensors are preferably arranged one behind the other in the circumferential direction. The sensors can advantageously have the same distance from one another. This has the main purpose partly that changes in speed can also be recorded relatively easily.

To simplify the circuitry preferably uses digital sensors. Digital output values can be essential processed more easily, especially linked together.

In the case of further training, that the sensors have symmetrical switching points. This will the accuracy of the system is further increased.

In another embodiment are the pulse lengths of the pulse generator always the same length. In particular, the magnetic ring the pole lengths equal long and even over the Scope distributed.

The pulse length preferably corresponds to that of covered the sensors Route. This means that the rotor can take positions where all sensors are switched at the same time or not switched are.

In the case of further training, that the output signals of the sensors are more conventional than the output signals correspond to optical or magnetic encoders, namely phase-shifted by 90 ° Rectangular pulses with an index pulse. Such signals are easy further processable or integrable into other systems.

The rotation angle sensor is preferred that of a conventional one Standard encoder interface can be connected. The switching and retrofitting effort is reduced to a minimum in this way.

Other advantages, features and details of Invention result from the dependent claims and the following Description in which a particularly preferred with reference to the drawing embodiment is described. You can those shown in the drawing and in the description and in the claims mentioned Features individually for be essential to the invention or in any combination.

The drawing shows:

1 a schematic representation of a magnet provided with several poles with a number of several sensors extending over a pole length;

2 two perspective views of a first embodiment with sensors arranged in the radial direction;

3 two perspective views of an embodiment with sensors arranged in the axial direction;

4 Output signals of individual sensors and various links between them. signals; and

5 a circuit diagram showing the linkage of 16 sensors.

In the 1 are schematically three poles 30 . 32 and 34 shown with the poles 30 and 34 one south pole and one pole 32 represents a north pole. About the pole length 36 The north pole extends a total of 16 sensors S1 to S16, which are packed tightly next to each other, ie in the circumferential direction of the poles 30 to 34 having magnets 18 , as in 2 shown, are arranged.

When in the 2 The illustrated embodiment is the magnet 18 is designed as a ring magnet and is driven by a rotor 20 , he around an axis 22 circulates, worn. The sensors S1 to S16 are located radially in relation to the magnet in the circumferential direction 18 ,

When in 3 illustrated embodiment, the sensors S1 to S16 are also in the immediate vicinity of the magnet 18 but in an axial arrangement.

Become the magnet 18 and the sensors S1 to S16 are moved relative to each other, for example by rotating the magnet, then the sensors S1 to S16 generate a sensor signal 1 to 16 which in the 4 is shown. The sensor S1 thus generates the signal 1 and sensor S16 generates the signal 16 , The signal is a rectangular curve that is constructed symmetrically, which means that the signal consists of a quiescent section 24 and a work section 26 which are of equal length. This is clear with the signal 16 to recognize.

If the 16 sensors S1 to S16 are now linked to one another in accordance with the following logic, the signals a to h result from this. The logical link is as follows:
S1 XOR S3 gives the signal a;
S5 XOR S7 gives the signal b;
S9 XOR S11 gives the signal c;
S13 XOR S15 gives the signal d;
S2 XOR S4 gives the signal e;
S6 XOR S8 gives the signal f;
S10 XOR S12 gives the signal g;
S14 XOR S16 gives the signal h.

The signals a to h are now logically linked to one another as follows:
a OR b OR c OR d gives signal A;
e OR f OR g OR h gives signal B.

These signals A and B are also in 4 shown. These signals A and B also have a rectangular shape and have a rest section 38 and a work section 40 that are of equal length. The phase difference between signals A and B is 90 °. The frequency of signals A and B is proportional to the speed of the rotor 20 ,

The sensors S1 and S3 are also linked as follows:
NOT S3 AND S1 gives the signal Z.

This signal Z is called an index pulse used.

From the above it follows that this system with 16 sensors S1 to S16 has a resolution that is 8 times larger than the resolution of a system with only two sensors.

In general it can be said that when using 4N sensors the resolution can be improved with symmetrical switching points, by arranging all sensors in a row and all sensors are at the same distance from each other. The total length of the sensors arranged one behind the other corresponds to the pole length or a multiple of this pole length. The angular offset of the individual sensors corresponds to 180 ° / 4N, so 45 ° / N.

With the use of a digital Logic can be 2N higher resolution can be achieved than in systems with normally switched sensors. Becomes e.g. a magnet with 100 pairs of poles is used for a conventional one System with two Hall sensors with a resolution of 100 pulses per revolution per channel and no index pulse is generated. In the system according to the invention with 4N Hall sensors, the maximum resolution corresponds to 200N Pulses per revolution per channel with an additional index pulse, whereby the output of two channels 90 ° out of phase is. If N = 4 is selected, so this system generates 800 pulses per revolution, which is conventional Applications in the automotive industry is sufficient.

The 5 finally shows the circuit of the 16 sensors S1 to 516, with a total of eight XOR elements 42 , which link the sensors S1 and S3, S5 and S7, S9 and S11, S13 and S15 as well as S2 and S4, S6 and S8, S10 and S12 as well as S14 and S16. XOR gates at the output 42 signals a to h are present. These signals a to h are over a total of six OR gates 44 linked together, from which the signals A and B are generated.

Sensors S1 and S3 are also linked to one another, sensor S3 being an EMERGENCY element 46 is connected downstream and the output of sensors S1 and the EMERGENCY element 46 with an AND gate 48 are linked together. The index signal Z is present at the output of the AND gate.

As already mentioned, magnets are preferred 18 used as a pulse generator, the sensors S1 to S16 being formed by Hall sensors. Magnets and Hall sensors are extremely robust and durable and therefore particularly suitable for use in motor vehicles.

Claims (16)

High-resolution rotation angle sensor for a rotor ( 20 ) with a rotatable with the rotor ( 20 ) connected pulse generator ( 28 ) and several fixed, with the pulse generator ( 28 ) interacting sensors (S1 to S16), each pulse of the pulse generator ( 28 ) a certain pulse length ( 36 Has), and each pulse of a plurality of sensors are associated (S1 to S16), characterized in that the number of sensors X = 4N, where N ≥ 1. Angle of rotation sensor according to claim 1, characterized in that the sensors (S1 to S16) have an angular distance of 45 ° / N. Angle of rotation sensor according to one of the preceding claims, characterized characterized in that the sensors (S1 to S16) in the circumferential direction are arranged one behind the other. Angle of rotation sensor according to one of the preceding claims, characterized characterized in that the sensors (S1 to S16) an equal distance from each other exhibit. Angle of rotation sensor according to one of the preceding claims, characterized characterized in that the sensors (S1 to S16) have digital output values. Angle of rotation sensor according to claim 5, characterized in that the sensors (S1 to S16) have symmetrical switching points. Angle of rotation sensor according to one of the preceding claims, characterized in that the pulse lengths ( 36 ) of the pulse generator ( 28 ) are the same length. Angle of rotation sensor according to one of the preceding claims, characterized in that the pulse length ( 36 ) corresponds to the distance covered by the sensors (S1 to S16). Angle of rotation sensor according to one of the preceding claims, characterized in that the X sensors (S1 to S16) are linked to one another as follows: S1 XOR S3 = a etc. S (x - 3) XOR S (x - 1) = d S2 XOR S4 = e etc. S (x - 2) XOR S (x) = h d, e, ..., h and the links generate signals a, .... Rotation angle sensor according to claim 9, characterized in that the signals a, ..., d, e, ..., h are linked together as follows: a OR ... OR d = A e OR ... OR h = B and the links generate A and B signals. Rotation angle sensor according to claim 10 or 11, characterized in that the sensor (S1) and the sensor (S3) are linked together as follows: NOT S3 AND S1 = Z and generate a signal Z. Angle of rotation sensor according to one of the preceding claims, characterized in that the pulse generator ( 28 ) a ring magnet ( 18 ) with at least one north pole ( 32 ) and a south pole ( 30 or 34). 1 Angle of rotation sensor according to one of the preceding claims, characterized characterized that the sensors (S1 to S16) are Hall sensors. Angle of rotation sensor according to claim 13, characterized in that the Hall sensors generate a square wave signal. Angle of rotation sensor according to one of the preceding claims, characterized characterized that the output signals of the sensors (S1 to S16) the output signals more conventional correspond to optical or magnetic encoders, namely around 90 ° out of phase Rectangular pulses with an index pulse. Angle of rotation sensor according to one of the preceding claims, characterized characterized in that it can be connected to a conventional standard encoder interface.