DE102014220465A1 - Sensor arrangement for detecting rotational angles on a rotating component - Google Patents

Abstract

The invention relates to a sensor arrangement (1) for detecting rotational angles (□) on a rotating component (3), in particular in a vehicle over several revolutions, with a first transducer (10), which circumferentially with a predetermined first gear ratio with the rotating component (3 ), and a second sensor (20), which is circumferentially coupled to the rotating component (3) with a predetermined second transmission ratio, wherein the first transmitter (10) in conjunction with a first transducer (30) a first angle information (☐ 1), and the second transmitter (20) in conjunction with a second transducer (40) generates a second angle information (□ 2) which can be evaluated to determine the current angle of rotation (□) of the rotating component (3). According to the invention, an evaluation and control unit (50) converts the first angle information (☐1) into a first frequency signal and the second angle information (☐2) into a second frequency signal and generates from the two frequency signals an output signal which indicates the current angle of rotation (☐). of the rotating component (3).

Description

The invention is based on a sensor arrangement for detecting rotational angles on a rotating component, in particular in a vehicle, according to the preamble of independent claim 1.

In known steering angle sensors, a counting wheel for determining the number of revolutions of the steering wheel is scanned without contact by means of magnetic field sensors. Such a system has the disadvantage that when the ignition is switched off, a quiescent current must be provided in order to be able to detect a rotation of the steering wheel when the ignition is switched off. With permanent non-use of the vehicle, this leads to an undesirable emptying of the vehicle battery. If such a quiescent current is not provided, the steering angle can no longer be clearly determined if the steering wheel is turned when the ignition is switched off or the battery is disconnected.

An improvement offer new steering wheel angle measurements with two angle sensors, which operate on a modified vernier principle and no longer have the disadvantage of quiescent supply.

So revealed the DE 195 06 938 A1 For example, a method and an apparatus for angle measurement in a rotatable body. In this case, the rotatable body cooperates circumferentially with at least two further rotatable bodies. The other rotatable bodies are designed, for example, as toothed wheels whose angular position is determined by means of two sensors. From the thus determined angular positions of the two additional rotatable body, the angular position of the rotatable body can then be determined. For clear statements to be possible, it is necessary for all three rotatable bodies or gears to each have a specific number of teeth or gear ratios. The method and the device can be used, for example, to determine the steering angle of a motor vehicle. The measuring principle described can be applied to any type of angle sensor, such as optical, magnetic, capacitive, inductive or resistive sensors. In this case, the further rotatable bodies act as transducers and the corresponding sensors act as transducers.

Disclosure of the invention

The sensor arrangement according to the invention for detecting rotational angles on a rotating component, in particular in a vehicle having the features of independent patent claim 1, has the advantage that by converting the angle information from at least two transducers into corresponding frequency signals, a simple and rapid evaluation of the signals for determining the current rotation angle is possible. In addition, components already used in the vehicle can be used for the evaluation of the frequency signals. During the evaluation, the difference between the two frequencies of the frequency signals is preferably formed and used as a vernier signal. This Noniussignal then clearly describes the position of the rotating component over several revolutions. The difference is formed for example by mixing and / or counting the frequency signals.

Embodiments of the sensor arrangement according to the invention for detecting rotational angles on a rotating component can be used, for example, as a steering angle sensor for determining the steering angle of a vehicle and / or in industrial controls.

Embodiments of the present invention provide a sensor arrangement for detecting rotational angles on a rotating component, in particular in a vehicle. Here, a first transmitter is circumferentially coupled to a predetermined first gear ratio with the rotating component and a second transmitter is circumferentially coupled to a predetermined second gear ratio with the rotating component. The first transmitter generates in conjunction with a first transducer first angle information, and the second transmitter generates in conjunction with a second transducer second angle information, which can be evaluated to determine the current angle of rotation of the rotating component. According to the invention, an evaluation and control unit converts the first angle information into a first frequency signal and the second angle information into a second frequency signal and generates from the two frequency signals an output signal which represents the current angle of rotation of the rotating component.

The term frequency signal refers to various signals below. Thus, for example, a more sinusoidal output signal of an oscillator oscillating at a certain frequency, or a square wave signal generated therefrom with the same frequency, or else a digital numerical value representing the oscillation frequency, can be called a frequency signal.

In the present case, the evaluation and control unit can be understood to mean an electrical circuit or an electrical device, such as a control unit, which detected Sensor signals processed or evaluated. The evaluation and control unit may have at least one interface, which may be formed hard and / or software. In the case of a hardware-based configuration, the interfaces can be part of a so-called system ASIC, for example, which contains a wide variety of functions of the evaluation and control unit. However, it is also possible that the interfaces are their own integrated circuits or at least partially consist of discrete components. In a software training, the interfaces may be software modules that are present, for example, on a microcontroller in addition to other software modules. Also of advantage is a computer program product with program code which is stored on a machine-readable carrier such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out the evaluation when the program is executed by the evaluation and control unit.

The measures and refinements recited in the dependent claims, advantageous improvements of the specified in the independent claim 1 sensor arrangement for detecting angles of rotation on a rotating component, in particular in a vehicle are possible.

It is particularly advantageous that the transducers each generate the angle information as inductance changes, which converts the evaluation and control unit into the frequency signals.

In an advantageous embodiment of the sensor arrangement according to the invention, the transducers may each have a disk-shaped main body with at least one electrically conductive metal surface, and the transducers may each have at least one areal detection coil. Here, the at least one electrically conductive metal surface can influence the inductance of the corresponding at least one detection coil as a function of the degree of coverage. In addition, the at least one planar detection coil can form the frequency-determining part of an oscillator circuit with a predetermined center frequency. In this case, the inductance changes of the areal detection coils may vary the center frequency of the corresponding oscillator circuit over a revolution of the corresponding transmitter within a predetermined measurement bandwidth. Preferably, the oscillator circuits are each designed as an LR oscillator. Thus, the angle information is first translated into an inductance change and then into a frequency change. The center frequency of the respective oscillator circuit changes during a movement of the transmitter between 0 and 360 ° to plus / minus half the measurement bandwidth, this measurement bandwidth is typically significantly lower than the center frequency.

In a further advantageous embodiment of the sensor arrangement according to the invention, a first oscillator circuit having a first area detection coil having a first center frequency, and a second oscillator circuit having a second area detection coil may have a second center frequency, which may differ from the first center frequency so that the frequency ranges the oscillator circuits can not overlap over the given measurement bandwidths. As a result, sign changes or zero crossings of the output signal or differential signal can be avoided in an advantageous manner.

In a further advantageous embodiment of the sensor arrangement according to the invention, an evaluation circuit to receive the current center frequencies of the oscillator circuits as first and second frequency signal and determine by mixing and / or counting a frequency difference of the two frequency signals and output as an output signal. In this case, the evaluation circuit can mix the frequency signals of the oscillator circuits analogously, filter with a low-pass filter and count out the low-pass filtered signal. The evaluation circuit can then output the counted signal as an output signal. Alternatively, the evaluation circuit can digitize the frequency signals of the oscillator circuits via at least one analog / digital converter and mix the digitized frequency signals, with a low-pass filter and count the low-pass filtered signal. Again, the evaluation circuit can output the counted signal as an output signal. As a further alternative, the evaluation circuit can convert the frequency signals of the oscillator circuits via threshold value switches into square-wave signals and in each case count out the frequency with a counter. The evaluation circuit can then digitally form the difference frequency of the two counters and output as an output signal. In a particularly cost-effective embodiment, the evaluation circuit can convert the frequency signals of the oscillator circuits via threshold value in rectangular signals, apply a first square wave signal as an input signal and a second square wave signal as a clock signal to a flip-flop, so that the flip-flop can oscillate with the difference frequency of the two square wave signals , The evaluation circuit can then detect the difference frequency at the output of the flip-flop and output as an output signal. The slow output oscillation of the flip-flop can be detected for example by a microcontroller, which can operate at low clock frequency, since the counter changes only with the slow difference frequency.

An embodiment of the invention is illustrated in the drawings and will be explained in more detail in the following description. In the drawings, like reference numerals designate components that perform the same or analog functions.

Brief description of the drawings

1 shows a schematic representation of an embodiment of a sensor arrangement according to the invention for detecting rotational angles on a rotating component.

2 shows a schematic block diagram of the sensor arrangement according to the invention 1 ,

3 shows a characteristic diagram of angle information, which the sensor arrangement according to the invention from 1 and 2 generated.

Embodiments of the invention

How out 1 to 3 can be seen, the illustrated embodiment comprises a sensor arrangement according to the invention 1 for detecting angles of rotation on a rotating component 3 over several revolutions a first transmitter 10 , which circumferentially with a predetermined first gear ratio with the rotating component 3 coupled, and a second transmitter 20 , which circumferentially with a predetermined second gear ratio with the rotating component 3 is coupled. Here, the first transmitter generates 10 in conjunction with a first sensor 30 a first angle information 1 , and the second transmitter 20 generated in conjunction with a second transducer 40 a second angle information 2 , The two angle information α1, α2 can then be used to determine the current angle of rotation of the rotating component 3 be evaluated. According to the invention, an evaluation and control unit converts 50 the first angle information 1 in a first frequency signal f1 and the second angle information 2 in a second frequency signal f2 and generates from the two frequency signals f1, f2 an output signal fN, which is the current angle of rotation of the rotating component 3 represents.

In the illustrated embodiment, the sensor arrangement according to the invention 1 for detecting angles of rotation on a rotating component 3 used as a steering angle sensor for determining the steering angle of a vehicle. Of course, alternative embodiments of the sensor arrangement according to the invention 1 for detecting angles of rotation on a rotating component 3 also be used in industrial controls.

How out 1 can be further seen, is the rotating component 3 as a gear with a body 5 and a main sprocket 7 executed with a first number of teeth. Alternatively, the rotating component 3 For example, be a shaft which is coupled to the gear with the main sprocket. The two transducers 10 . 20 are also designed as gears, with the first transmitter 10 a basic body 12 with a first sprocket 14 and the second transmitter 20 a basic body 22 with a second sprocket 24 having. The number of teeth of the sprockets 7 . 14 . 24 are different. So the main sprocket points 7 for example 42 Teeth, the first sprocket 14 for example 26 Teeth and the second sprocket 24 for example 28 Teeth on. How out 1 and 2 is further apparent, the rotational movement α of the rotating component 3 on the two transducers 10 . 20 translated. The transducers 30 . 40 convert the respective angle information α1, α2 in the range of 0 to 360 ° of the two transducers 10 . 20 in a corresponding frequency signal f1, f2 to, for example, each represents an oscillation frequency of an oscillator and depending on the position of the corresponding transducer 10 . 20 is. The evaluation and control unit 50 generated, or calculated from the frequency signal f1, f2, the output signal fN, which also over several revolutions of the rotating component 3 is unique. The course of the angle information α1, α2 over several revolutions of the rotating component 3 in the range of 0 to 1440 ° is in 3 shown.

In the illustrated embodiment, the detection of the angle of rotation of the rotating component takes place 3 with the help of the eddy current effect. How out 1 further apparent, the disc-shaped base body 12 . 22 the transmitter 10 . 20 each a spiral-shaped electrically conductive metal surface 16 . 26 on. The transducers 30 . 40 each have two-dimensional detection coils 32 . 42 on, on a non-illustrated printed circuit board with a predetermined distance above or below the respective transmitter 10 . 20 are arranged.

Here, the electrically conductive metal surfaces influence 16 . 26 eddy current effects the inductance of the corresponding detection coil 32 . 42 depending on the degree of coverage. The respective flat detection coil 32 . 42 is so in relation to the corresponding metal surface 16 . 26 arranged that the degree of coverage at a current rotation angle α1, α2 of the associated transmitter 10 . 20 of 0 ° has a maximum value and at a current rotation angle α1, α2 of 180 ° has a minimum value. At a current rotation angle α1, α2 of the associated transmitter 10 . 20 of 0 ° overlap in the illustrated embodiment, the electrically conductive metal surfaces 16 . 26 the flat detection coils 32 . 42 Completely. At a rotation angle of 180 °, the overlap goes to zero. About the eddy current effect, the inductance of the corresponding detection coil 32 . 42 changed, so that the value of the inductance clearly the position of the associated transmitter 10 . 20 ranging from 0 to 360 °. In the illustrated embodiment, the flat detection coils form 32 . 42 in each case the frequency-determining part of an oscillator circuit 52 . 54 with a predetermined center frequency f0 ₁ , f0 ₂ off. The inductance changes of the flat detection coils 32 . 42 vary the center frequency f0 ₁ , f0 _{2 of} the corresponding oscillator circuit 52 . 54 over one revolution of the corresponding transmitter 20 . 30 within a given measurement bandwidth. Preferably, the oscillator circuits 52 . 54 each implemented as an LR oscillator. The angle information α1, α2 is then first translated into an inductance change and then into a frequency change.

How out 2 is further apparent, has in the illustrated embodiment, as part of the evaluation and control unit 50 executed first oscillator circuit 52 with the first flat detection coil 32 a first center frequency f0 ₁ , and one as part of the evaluation and control unit 50 executed second oscillator circuit 54 points with the second flat detection coil 42 a second center frequency f0 ₂ , which differs from the first center frequency f0 ₁ so that the frequency ranges of the oscillator circuits 52 . 54 do not overlap over the given measuring bandwidths. The evaluation and control unit 50 includes an evaluation circuit 56 representing the current center frequencies f0 ₁ , f0 _{2 of} the oscillator circuits 52 . 54 receives as first and second frequency signal f1, f2 and determined by mixing and / or counting a frequency difference of the two frequency signals f1, f2 and outputs as an output signal fN.

The evaluation circuit 56 can the frequency signals f1, f2 of the oscillator circuits 52 . 54 For example, analog mix, filter with a low-pass filter, not shown, and count out the low-pass filtered signal. The evaluation circuit 56 then outputs the counted signal as the output signal fN. Alternatively, the evaluation circuit 56 the frequency signals f1, f2 of the oscillator circuits 52 . 54 Digitize via at least one analog / digital converter, not shown, and mix the digitized frequency signals f1, f2, filter with a low-pass filter and count the low-pass filtered signal. The evaluation circuit 56 then outputs the counted signal as the output signal fN.

Another evaluation option is the evaluation circuit 56 the frequency signals f1, f2 of the oscillator circuits 52 . 54 via threshold switches not shown to convert into square wave signals and in each case with a counter, not shown, the frequency f1, f2 count. The evaluation circuit 56 then digitally forms the difference frequency of the two counters and outputs the digital numerical value as an output signal fN. Alternatively, the evaluation circuit 56 the frequency signals f1, f2 of the oscillator circuits 52 . 54 via threshold switch into rectangular signals and convert a first square wave signal, which represents, for example, the first frequency signal f1, as an input signal to a flip-flop, which is preferably designed as a D-flip-flip. A second square-wave signal, which represents, for example, the second frequency signal f2, can be applied as a clock signal to the flip-flop. As a result, the flip-flop oscillates with the difference frequency of the two square-wave signals, wherein the evaluation circuit 56 detects the difference frequency at the output of the flip-flop and outputs as output signal fN. The slow output oscillation of the flip-flop is then detected by a microcontroller, which is part of the evaluation and control unit 50 is and can work with low clock frequency, since the counter changes only with the slow difference frequency. This represents a particularly advantageous and cost-effective embodiment.

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

• DE 19506938 A1 [0004]

Claims (10)

Sensor arrangement ( 1 ) for detecting angles of rotation (α) on a rotating component ( 3 ) in particular in a vehicle over several revolutions with a first transmitter ( 10 ), which circumferentially with a predetermined first gear ratio with the rotating component ( 3 ) and a second transmitter ( 20 ), which circumferentially with a predetermined second transmission ratio with the rotating component ( 3 ), the first transmitter ( 10 ) in conjunction with a first transducer ( 30 ) generates a first angle information (α1), and the second transmitter ( 20 ) in conjunction with a second transducer ( 40 ) generates a second angle information (α2) which is used to determine the current angle of rotation (α) of the rotating component ( 3 ) are evaluable, characterized in that an evaluation and control unit ( 50 ) converts the first angle information (α1) into a first frequency signal (f1) and the second angle information (α2) into a second frequency signal (f2) and generates an output signal (fN) from the two frequency signals (f1, f2) which represents the current angle of rotation (α) of the rotating component ( 3 ). Sensor arrangement according to claim 1, characterized in that the transducers ( 30 . 40 ) generate the angle information (α1, α2) in each case as inductance changes which the evaluation and control unit ( 50 ) into the frequency signals (f1, f2). Sensor arrangement according to claim 1 or 2, characterized in that the transducers ( 10 . 20 ) each have a disk-shaped base body ( 12 . 22 ) with at least one electrically conductive metal surface ( 16 . 26 ) and the transducers ( 30 . 40 ) in each case at least one areal detection coil ( 32 . 42 ), wherein the at least one electrically conductive metal surface ( 16 . 26 ) the inductance of the corresponding at least one detection coil ( 32 . 42 ) depending on the degree of coverage. Sensor arrangement according to claim 3, characterized in that the at least one flat detection coil ( 32 . 42 ) the frequency-determining part of an oscillator circuit ( 52 . 54 ) with a predetermined center frequency (f0 ₁ , f0 ₂ ) is formed, wherein the inductance changes of the areal detection coils ( 32 . 42 ) the center frequency (f0 ₁ , f0 ₂ ) of the corresponding oscillator circuit ( 52 . 54 ) over one revolution of the corresponding transmitter ( 20 . 30 ) vary within a given measurement bandwidth. Sensor arrangement according to claim 4, characterized in that a first oscillator circuit ( 52 ) with a first flat detection coil ( 32 ) has a first center frequency (f0 ₁ ), and a second oscillator circuit ( 54 ) with a second flat detection coil ( 42 ) has a second center frequency (f0 ₂ ) which differs from the first center frequency (f0 ₁ ) such that the frequency ranges of the oscillator circuits ( 52 . 54 ) do not overlap over the given measuring bandwidths. Sensor arrangement according to claim 5 or 6, characterized in that an evaluation circuit ( 56 ) the current center frequencies (f0 ₁ , f0 ₂ ) of the oscillator circuits ( 52 . 54 ) receives as first and second frequency signal (f1, f2) and determined by mixing and / or counting a frequency difference of the two frequency signals (f1, f2) and outputs as an output signal (fN). Sensor arrangement according to claim 6, characterized in that the evaluation circuit ( 56 ) the frequency signals (f1, f2) of the oscillator circuits ( 52 . 54 ) mixes analog, filters with a low-pass filter and counts the low-pass filtered signal, the evaluation circuit ( 56 ) outputs the counted signal as an output signal (fN). Sensor arrangement according to claim 6, characterized in that the evaluation circuit ( 56 ) the frequency signals (f1, f2) of the oscillator circuits ( 52 . 54 ) digitizes and mixes the digitized frequency signals (f1, f2), filters with a low-pass filter and counts the low-pass filtered signal, the evaluation circuit ( 56 ) outputs the counted signal as an output signal (fN). Sensor arrangement according to claim 6, characterized in that the evaluation circuit ( 56 ) the frequency signals (f1, f2) of the oscillator circuits ( 52 . 54 ) is converted into square wave signals via threshold value switches and the frequency (f1, f2) is counted in each case with a counter, the evaluation circuit ( 56 ) Digitally forms the difference frequency of the two counters and outputs as an output signal (fN). Sensor arrangement according to claim 6, characterized in that the evaluation circuit ( 56 ) the frequency signals (f1, f2) of the oscillator circuits ( 52 . 54 ) via threshold switches into square waves, a first square wave signal as an input signal and a second square wave signal as a clock signal to a flip-flop applies, so that the flip-flop oscillates with the difference frequency of the two square wave signals, wherein the evaluation circuit ( 56 ) detects the difference frequency at the output of the flip-flop and outputs as an output signal (fN).

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