DE102018133120A1 - Device and method for non-contact rotation measurement - Google Patents

Abstract

The invention relates to a device (10) and a method for non-contact rotation measurement, comprising a rotation body (12) rotatably mounted on an axis of rotation (14) with n-fold rotational symmetry and a beam-divergent or beam-convergent measuring system (20, 201, 202, 203, 204), which has at least one radiation source (22), at least one radiation receiver (32, 34), an evaluation device (40) and an optical path (24) between the at least one radiation source (22) and the at least one radiation receiver (32, 34) In which a rotating body (12) is arranged. According to the invention, divergent or convergent radiation is thrown onto the rotating body (12) of the device (10), with radiation passing at least one side of the rotating body (12) in at least one radiation receiver (32, 34) of the device (10) is detected and / orb) at least part of the reflection from the rotating body (12) radiation is detected in at least one radiation receiver (32, 34) of the device, and at least one rotation state variable of the rotation of the rotating body (12) is determined from the amount of radiation detected and / or at least one quantity derived therefrom.

Description

The invention relates to a device and a method for non-contact rotation measurement, comprising a rotation body rotatably mounted on an axis of rotation with an n-fold rotational symmetry.

The present invention is in the field of, in particular optical, contactless measurement technology for the characterization of movements, in particular rotation angle and rotation. In this context, the term optical measurement technology is not limited to the visible range of the electromagnetic spectrum, but also encompasses the ultraviolet range, the infrared range and other frequency ranges that can be optically characterized, such as the RF and microwave range, or in the even more short-wave range Area, for example the X-ray area. Here, specific properties of the respective frequency range can be used, such as the degree of damping of the media present in the application. An application example of this is a flow sensor with a rotating body that is rotated by the flow of a fluid that is, for example, non-transparent to visible light. In such a case, a measuring frequency is used for which the fluid is transparent.

The state of the art of non-contact rotation measurement is extensive and includes speed measurements with pulse generators, sensors with angle-resolved signal detection, analog optical sensors such as rotating polarization filters, intensity-dependent reflection measurements on a rotating wheel, light beam deflection on a segmented, reflecting shaft as well as magnetic measurement methods in which Changes in a magnetic field can be detected by rotation.

The measuring principle with pulse generators based on light barriers, for example, is such that one pulse signal or a few pulse signals are generated per revolution. The measurement is carried out without contact and therefore without mechanical loads. However, no angle of rotation, no preferred position and no imbalance are detected. At low flow speeds, there are large time intervals between the signal pulses. The signal rate is determined here by the process, not by the measured value acquisition system or the evaluation unit.

Sensors with angularly resolved signal detection often comprise an optically finely segmented disk, which is scanned with one or more light barriers in order to determine the change in the angle of rotation. Digitally coded segment discs enable the discreet determination of absolute angles of rotation. This segment disc must be attached to a shaft. This results in high mechanical requirements for the positioning, and the mounting of the optical sensor units is high.

When using a rotating polarization filter in combination with a fixed polarization filter, when using several detectors and polarization filters, the light amplitude of the source can be compensated and a high angular resolution can be generated by means of phase-shifted signals. However, this technology is associated with high costs and high mechanical requirements for the arrangement of the polarization filters on the rotating shaft. Multiple detectors are also required for accurate absolute angle detection.

In the case of an intensity-dependent reflection measurement on a rotating wheel, for example on the cylindrical surface of a rotor, an intensity-dependent structuring is applied, for example a gray wedge or a pattern dependent on the angle of rotation. In this case too, an angle of rotation can be detected in the entire rotation range from 0 ° to 360 °. However, an intensity-dependent pattern must be applied to the shaft. This cannot be miniaturized arbitrarily. Furthermore, in the field of microsystem technology and microfluidics, for example, the required design of the rotating body is often not possible.

The light beam deflection of a segmented, reflecting wave with detection of the angle of rotation with the aid of a segmented receiving unit or several receivers also allows a precise determination of the angle of rotation, which is implemented without contact. However, the signal detection itself, for example by means of a laser beam and a line camera, is complex and, due to the read speed of the line camera, the rotational speed at which this method works is limited. Because of the reflection, the method can only be used within a certain angle segment, for example up to 180 °.

In contrast, the present invention has for its object to provide a device and a method for non-contact rotation measurement, which is robust and can be realized with high measurement accuracy and little effort.

1. a) der Rotationskörper die Strahlung in einer Transmissionsanordnung entsprechend einer momentanen Winkellage des Rotationskörpers teilweise abschattet und der wenigstens eine Strahlungsempfänger auf einer der Strahlungsquelle gegenüberliegenden Seite des Rotationskörpers angeordnet ist und einen nicht abgeschatteten Teil der divergenten Strahlung erfasst, und/oder
2. b) der Rotationskörper die Strahlung in einer Reflexionsanordnung entsprechend einer momentanen Winkellage des Rotationskörpers teilweise reflektiert und der wenigstens eine Strahlungsempfänger auf der gleichen Seite wie die Strahlungsquelle relativ zum Rotationskörper angeordnet ist und einen reflektierten Teil der Strahlung erfasst,

wobei die Auswertungsvorrichtung eingerichtet ist, aus der Menge der erfassten Strahlung und/oder wenigstens einer daraus abgeleiteten Größe wenigstens eine Rotationszustandsgröße des Rotationskörpers zu ermitteln.This object is achieved by a device for non-contact rotation measurement, comprising a rotary body rotatably mounted on an axis of rotation with an n-fold rotational symmetry and a beam-divergent or beam-convergent measuring system which has at least one Radiation source, at least one radiation receiver, an evaluation device and an optical path between the at least one radiation source and the at least one radiation receiver, in which a rotating body is arranged, wherein the radiation source is designed to divergent or convergent radiation towards the rotating body on the To emit a rotating body, the envelope of which includes a maximum circumferential rotation circle of the rotating body, wherein

1. a) the rotating body partially shades the radiation in a transmission arrangement in accordance with an instantaneous angular position of the rotating body and the at least one radiation receiver is arranged on a side of the rotating body opposite the radiation source and detects an unshaded part of the divergent radiation, and / or
2. b) the rotating body partially reflects the radiation in a reflection arrangement corresponding to an instantaneous angular position of the rotating body and the at least one radiation receiver is arranged on the same side as the radiation source relative to the rotating body and detects a reflected part of the radiation,

wherein the evaluation device is set up to determine at least one rotational state variable of the rotating body from the quantity of radiation detected and / or at least one variable derived therefrom.

In the context of the present invention, n is always a finite positive integer. The case n = 1 means that the measurement signal is only repeated after the complete rotation of the rotating body by 360 °.

The invention is based on the basic principle of using the apparent expansion of the rotary body, which changes constantly in the course of a rotation of the rotary body, due to its shape for signaling and to correlate the received signals with the respective angle of rotation or other rotational state variables. The only cross-sectional shape of a rotating body with which such a measurement does not work in principle is the circular shape (with the circular shape n = ∞), since the projection of the cylindrical rotating body does not change in the course of one revolution of a cylindrical object, i.e. no signal that changes over time is available. With such an arrangement, only the position of the rotating body in the directions perpendicular to the axis of rotation can be determined. In the case of a structured body of revolution, its projection changes transversely to the axis of rotation in the course of one revolution in a characteristic manner, which is used to determine the state of rotation.

The amount of shading or unshaded light therefore changes periodically with the period of one revolution or several times per complete revolution. This results in a radiation signal that is modulated over time, which can be evaluated in relation to rotational state variables such as the angular position, angular velocity, angular acceleration, rotational direction or idle position. In the context of the present invention, the measurement frequency of the radiation is preferably in the visible optical range, in the infrared range, in the UV range, in the HF range, in the microwave range or at even shorter wavelengths, insofar as these can be shaded by suitable materials of the rotating body. Materials which are non-transparent, partially transparent or transparent for the different wavelength ranges are known, and the present invention is not restricted to certain materials in this regard. By suitable use of different materials with different transparency for the measurement frequency used, a periodicity of n = 1 can be created optically, i.e. the measurement signal is only repeated after the rotation body has been completely rotated through 360 ° around the rotation axis, although the rotation body itself, for example, has higher-order rotational symmetry.

The advantage of a reflective arrangement compared to a shading-based arrangement lies in a more compact design and in the simpler coupling of the optical measuring system from only one side. An existing segmented wave can also be used here as long as it at least partially reflects the light and its reflective properties do not change too much over time. The amount of light or radiation or radiation energy detected by the receiving unit also depends in this case on the geometric conditions, but in turn has the periodicity necessary for the rotation or rotation angle measurement in the course of the rotation of the rotating body.

Sizes which are derived from the amount of radiation detected in the context of the invention include the temporal progression, understood in the first, second or higher derivation, as well as measurement variables composed of several signals, such as differences or quotients of the measured light quantities of different radiation receivers.

The fact that the radiation is anisotropic, i.e. divergent or convergent, i.e. one Spreading or the opposite of a spreading introduces a non-linearity into the system, which leads to the fact that different angles of rotation of the rotating body can be distinguished from one another, which would not be distinguishable from one another when using a parallel beam, the use of several radiation receivers from different areas of the rotating body can be switched off, when resolving ambiguities is advantageous.

Alternatively, in the case of a beam-convergent system in which a plurality of radiation sources transmit radiation convergent to a single receiver, a resolution of ambiguities can also be achieved in that the plurality of radiation sources are operated or can be distinguished from one another, for example by uniquely distinguishable modulation, for example by alternating radiation , or the use and differentiation of different wavelengths on the receiver side if the receiver permits resolution according to color or wavelength.

In one embodiment, a standard LED is used as a radiation source and one or two standard photodiodes are used as radiation receivers as a cost-effective solution. The system according to the invention or the device according to the invention can be applied to microsystems and can also be produced in MEMS or MO-EMS technology (microelectromechanical or microoptoelectromechanical systems).

The device according to the invention realizes a non-contact measuring principle of the angle of rotation and variables derived therefrom, such as angular velocity and angular acceleration, and can be implemented as an inexpensive arrangement, since the requirements for the precision of the optics are not very high. The mostly non-linear signal curves can be recorded and processed by calibration. The current angle can be determined at any point in time, the temporal resolution of the angle measurement is thus determined by the data acquisition system and not by the rotation, as is the case, for example, with incremental encoders which do not deliver any signals in the idle state. There are also no additional requirements for the rotating body, such as with regard to magnetization, color design or the use of polarization elements. This means that existing rotary bodies can also be retrofitted with a system according to the invention. For this purpose, the mechanics of the shaft on which the rotating body is arranged do not have to be disassembled.

The rotation measurement also has a high dynamic range, while the mechanical precision between the rotor and the measuring arrangement does not have to be very high. A change in position of the rotational axis of the rotating body in the axial direction has no influence on the measurement. A change in position in the horizontal direction, that is to say away from the radiation source or towards the radiation source, is detected after one revolution or with at least two receivers directly at any angular position and can be compensated automatically. A change in position in the vertical direction is also recognized on the basis of the time course and can be compensated for on a model basis. The system can be designed robustly for this. Additional information is available through the possible detection of such error sizes. In this way, vibrations of the shaft can also be identified and analyzed, which enables fault monitoring of the shaft. Defective bearings, wear or asymmetrical loads can be identified. The corresponding changes in the detected traces are characteristic of these error cases and can be modeled or calculated.

The device according to the invention allows the angle of rotation, the direction of rotation, the angle of rotation speed, the position or other derived quantities to be determined with the aid of a simple and inexpensive construction and without or with only minimal interventions in the rotating mechanics. The measuring principle can be applied to already existing rotors or shafts profiled in the plane of rotation, such as a flow impeller or an angular or oval shaft. It is also possible to optimize a rotating body specifically for an application, to supplement it later in an existing system or to integrate it in a newly developed angle of rotation sensor. In particular in the case of a flow sensor, the impeller is preferably optimized in terms of flow technology, inter alia with a low mass, low rotational moment of inertia, low-friction mounting and adapted shaping.

With the aid of an angle-resolved signal detection made possible by the device according to the invention, it is possible to detect rotation state variables such as the rotation speed even at low speeds using a measurement rate specified by the measuring system. In addition, the rotation angle measurement can detect deflections from the rest position, pendulum movements and asymmetrical rotations, which often occur at low flow velocities. Such information is important for error analysis and measured value correction, for example with regard to start-up behavior, subsequent behavior when there are changes in flow velocity or Slip compensation. They thus contribute to an increase in the measuring accuracy of such flow sensors.

In principle, the measuring principle according to the invention also works in the case of rotating bodies with a high rotational symmetry. However, very high n make the periodicity very short and the available amplitude of the change in the amount of radiation that is received by the radiation receivers becomes very small. For example, if n = 30, only an angular pull of 12 ° can be resolved. The rotary body is therefore preferably designed with n-fold rotational symmetry with 1 n n 20 20, preferably with 1 n n 10 10. This is related to the shading properties of the rotating body. With appropriate values for n, a good resolution and a sufficiently large periodicity of the measurement signal can be achieved. Alternatively or additionally, the rotating body is designed as an impeller with n blades or as a polygonal body with n corners and n edges that is regular or irregular in cross section.

Since this measurement method is based on an amplitude measurement, it makes sense to stabilize the source (s) or to reference their emission in order to compensate for possible fluctuations that would also be contained in the measurement signal. Targeted modulation of the source can also be used to compensate for cross influences such as ambient light.

The radiation is preferably emitted as a divergent or convergent radiation fan or as two or more diverging or converging beams. In this case, a divergent radiation fan is a diverging beam, while diverging beams denote separate beams, which can each be divergent or else parallel and run in different, divergent directions. The situation is the reverse for convergent radiation fans or beams. The measuring principle according to the invention can be implemented with all four variants.

In the optical arrangement, the switchover from a divergent system to a convergent system is achieved in a simple manner by exchanging the light source (s) and receiver (s). This results in a convergent radiation behavior in the beam-convergent system.

Advantageously, at least two radiation receivers are included, which are arranged to receive parts of the radiation that pass or are reflected on opposite sides of the rotating body. This takes advantage of the fact that, depending on the position of rotation, the shading or reflection from the rotation body runs differently on the opposite sides of the rotation body during its rotation, so that ambiguities that would arise if only one radiation receiver were used can be eliminated. Alternatively, two radiation receivers can also be arranged next to one another along the axis of rotation of the rotating body, but on the same side of the rotating body, in which case the rotating body is preferably configured differently in its axial direction, so that these two radiation receivers receive and record different temporal profiles of their measurement signals in this way a determination of the rotation state variables is possible.

To increase the measuring accuracy, several such arrangements can also be arranged next to one another on a shaft, an angular offset between the systems preferably being realized.

In an advantageous development, the evaluation device is set up to form a ratio and / or a difference in the radiation received by the at least two radiation receivers. For example, forming a quotient is suitable for excluding fluctuations in the radiation source, since these are divided into the quotient. A difference measurement results in a composite signal which can provide an improved resolution of ambiguities.

If two or more beam-divergent and / or beam-convergent measuring systems are advantageously included, in particular with a common evaluation device, the two or more beam-divergent measuring systems being arranged at an angle to one another with respect to the rotating body, the two or more beam-divergent measuring systems in particular being geometrically shielded from one another and / or when operating with different measuring frequencies, alternatively or additionally with frequency filters, in particular bandpass filters or edge filters, are shielded against one another, then it is possible to improve the accuracy of the measurement and to suppress ambiguities of the measuring signals.

One embodiment consists of a combination of shadowing and reflection-based measurement systems.

A particularly simple embodiment consists in that two radiation receivers are designed as flat radiation receivers, each of which covers part of the divergent radiation, while in another, likewise simple embodiment, two, in particular with respect to the axis of rotation of the rotating body mutually symmetrical combinations of a small-area radiation receiver and a focusing element are included, in particular a lens or lens combination or a focusing mirror, by means of which a respective part of the divergent radiation is focused on the small-area radiation receiver. The first-mentioned embodiment can do without focusing of the elements on the receiver side, while the second alternative embodiment, in which focusing of the elements is used, uses small-area radiation receivers, which are very inexpensive and responsive.

In embodiments of the invention, mirrors are provided which expand or bundle the radiation on the radiation source side and / or which bundle or expand the parts of the radiation on both sides of the rotating body on the side of the at least one radiation receiver. In this way, an anisotropic, that is to say diverging or converging optical beam path is produced, which can be realized in a very small size. Concave mirrors are suitable as reflective elements, but convex mirrors can also be used. Such concave mirrors can be realized very inexpensively within a sensor housing by mirroring a suitable shape.

If the rotating body is partially transparent or transparent or partially reflective or reflective, at least in sections, this opens up further possibilities for signal shaping and improvement of the suppression of ambiguities. In the case of a partially reflective or reflective design, the rotary body can advantageously be designed to be reflective, reflective or roughly reflective. In a reflection arrangement, the reflector preferably has a rough reflecting surface. Compared to a smooth, reflecting surface, the range of rotation angles that can be detected with a detector can be significantly increased.

A design of the rotating body in which the transparency or reflectivity of the rotating body increases from the inside to the outside in relation to the measurement frequency used can be selected in such a way that a largely linear signal curve is set. In the case of a rotating body which is equipped, for example, with a plurality of vanes, the individual vanes, which can otherwise be geometrically identical, can be designed with different transparency profiles in order to generate characteristic signal profiles that can be distinguished from one another in a signal analysis in the evaluation device, so that the Periodicity of the measurement signal is maximized to 360 °. This also opens up the possibility, for example, of providing axially adjacent regions of the rotating body with different transparency in the direction of the axis of rotation and treating the regions with different transparency separately from one another during measurement, so that in this case too, ambiguities that still occur when using only one system could be suppressed.

One or more optical elements for optimizing, in particular linearizing, an intensity distribution of the divergent or convergent radiation are preferably included. In one embodiment, this means that a reflective element on the radiation source side is shaped and optionally equipped with such a reflectivity or its course that a profile of the light intensity within the radiation field is established, which leads to an optimization, for example linearization, of the Waveforms leads. Alternatively or additionally, a filter, for example a partially transparent pane with a preset transparency curve, can be used, which models the intensity distribution of the radiation as a filter.

A device for stabilizing or referencing the light source is preferably included, by means of which the light source is stabilized or fluctuations in the radiation intensity of the light source are compensated for in the measured signals. Stabilization, for example by stabilizing the current intensity and / or voltage that is or are supplied to the light source, or by measuring an instantaneous light intensity that is fed back to the current source, improves the measurement accuracy. The measurement of the instantaneous light intensity of the light source can also be used as a reference for the measured signals, for example by forming the ratio of the measured signal and the measured instantaneous light intensity.

1. a) an wenigstens einer Seite des Rotationskörpers vorbei gelangende Strahlung in wenigstens einem Strahlungsempfänger der Vorrichtung erfasst wird und/oder
2. b) wenigstens ein Teil der von dem Rotationskörper reflektierten Strahlung in wenigstens einem Strahlungsempfänger der Vorrichtung erfasst wird,

und aus der Menge der erfassten Strahlung und/oder wenigstens einer daraus abgeleiteten Größe wenigstens eine Rotationszustandsgröße der Rotation des Rotationskörpers ermittelt wird.The object on which the invention is based is also achieved by a method for non-contact rotation measurement in a device according to the invention described above, in which a divergent or convergent radiation is thrown onto the body of rotation of the device, wherein

1. a) radiation passing at least one side of the rotating body is detected in at least one radiation receiver of the device and / or
2. b) at least part of the radiation reflected by the rotating body is detected in at least one radiation receiver of the device,

and from the amount of radiation detected and / or at least one quantity derived therefrom at least one rotational state variable of the rotation of the rotating body is determined.

The method according to the invention realizes the same properties, features and advantages as the device according to the invention described above and is essentially based on the evaluation of detector analog signals which are caused by the shadow cast by a shading rotating body or by the throw of the light or radiation cone of a reflecting rotating body in the divergent radiation field arise.

As already mentioned, depending on the properties of the field of the emitted radiation and the shape and distribution of the transparency of the rotating body, the measuring signal or the resulting measuring signals can be non-linear, in any case characteristic. However, since the course of the amount of light play or the received radiation can be reproduced for each angle setting of the rotating body in the presence of a radiation field and can either be calculated or measured, it is a question of calibrating the device from concrete measured values during operation to a rotation state or to infer a rotational state quantity.

In the simplest case, one, two or more measurement signals relating to radiation intensities are recorded and passed on to the evaluation device, which then uses a look-up table or a simple calculation on the basis of models or known measurement values to determine the rotation state variable. The evaluation device itself can be designed as a processor-based computer, but also in a simple manner, for example as an FPGA (field programmable gate array). The invention is not limited to this.

The evaluation of the alternating components and the direct components of the received signals also enables the compensation of individual changes in the optical light paths. To further improve the measurement accuracy, it is provided to modulate the radiation source so that the influence of extraneous light or stray light from the surroundings can be suppressed.

If at least two radiation receivers detect radiation that has passed on opposite sides of the rotating body and a difference and / or a ratio is calculated from the detected amounts of radiation, from which at least one rotational state variable of the rotation of the rotating body is determined, this has the advantage that fluctuations in the light intensity or radiation intensity have no influence on the measurement result when calculating the ratio, since both channels are affected in the same way. A difference measurement of the two channels leads to a composite signal which can be used to suppress ambiguities. Ratio measurement can also be used to compensate for long-term drifts.

Advantageously, an angular position, angular velocity, angular acceleration and / or direction of rotation of the rotating body is or are determined as the rotational state variable.

The interference compensations used for this determination of the rotational state size, for example the position error of the rotor, can be output as additional information on the position of the axis of rotation.

The signal curves for a normal case in which the rotating body rotates on its predetermined axis of rotation are easy to measure or calculate and are repeated with every revolution. The device according to the invention and the method according to the invention additionally offer the possibility of inferring deviations from regular operation from deviations from regular measurements, in particular vibrations and / or displacements of the axis of rotation or asymmetrical load. Any deviation of the rotating body with respect to the normal position, that is to say centered on the nominal axis of rotation, leads to an influencing of the measurement signal in at least one channel. This characteristic deviation can be used to calculate the deviation from the nominal rotation axis, the course of which can also be used to determine permanent displacements or also deviations that change over time, such as vibrations or shocks.

Further features of the invention will become apparent from the description of embodiments according to the invention together with the claims and the accompanying drawings. Embodiments according to the invention can fulfill individual features or a combination of several features.

• 1 schematisch eine erfindungsgemäße Vorrichtung im Querschnitt,
• 2 Signalverläufe von Messgrößen und abgeleiteten Messgrößen einer erfindungsgemäßen Vorrichtung gemäß 1,
• 3 einen zeitlichen Verlauf eines Messsignals eines auslaufenden Rotationskörpers,
• 4a) - 4d) Varianten erfindungsgemäßer Vorrichtungen in schematischer Darstellung,
• 5a) - 5d) Varianten erfindungsgemäß einsetzbarer Rotationskörper im Querschnitt,
• 6a) - 6d) Varianten erfindungsgemäß einsetzbarer Rotationskörper in Draufsicht,
• 7 eine erfindungsgemäße Vorrichtung in Reflexionsanordnung und
• 8 eine weitere erfindungsgemäße Vorrichtung in Reflexionsanordnung.

The invention is described below without restricting the general inventive concept on the basis of exemplary embodiments with reference to the drawings, reference being expressly made to the drawings with regard to all details according to the invention not explained in more detail in the text. Show it:

• 1 schematically a device according to the invention in cross section,
• 2nd Signal curves of measured variables and derived measured variables according to a device according to the invention 1 ,
• 3rd a time course of a measurement signal of a rotating body,
• 4a) - 4d ) Variants of devices according to the invention in a schematic representation,
• 5a) - 5d ) Variants of rotary bodies which can be used according to the invention in cross section,
• 6a) - 6d ) Variants of a rotating body that can be used according to the invention in plan view
• 7 a device according to the invention in a reflection arrangement and
• 8th another device according to the invention in a reflection arrangement.

In the drawings, the same or similar elements and / or parts are provided with the same reference numerals, so that a renewed presentation is not given.

1 shows a device 10 According to the invention for contactless rotation measurement in a schematic cross-sectional representation. In the center is a rotating body designed as an impeller with two blades 12th that is on a central axis of rotation 14 , which extends into the image plane, is rotatably supported. A beam divergent measuring system 20 for the rotating body 12th includes a small radiation source 22 as part of a transmission system which, in addition to the radiation source 22 a mirror designed as a concave mirror 23 and a filter element 25th includes, the mirror 23 Radiation from the radiation source 22 towards the rotating body 12th steers and the filter element 25th , which is optional, serves as a diaphragm to limit the radiation and, if necessary, to model it with a gradual transparency. The result is a diverging optical path 24th by the envelope 26 '26' is limited to the outside. This optical path 24th includes the maximum circumferential rotation circle 16 of the rotating body 12th .

In the in 1 The initial example shown is the envelope 26 , 26 'a tangent to the circumferential rotation circle 16 , so that with every full rotation of the rotating body 12th the upper half of the optical path or the lower half of the optical path 24th is completely shaded once at different times, corresponding to a phase shift. In alternative embodiments, the optical path 24th be chosen so that it is laterally opposite the maximum circumferential rotation circle 16 is further, so that even in the case of maximum coverage there is still light or radiation on the rotating body 12th passed by. Such an arrangement is robust against vibrations or changes in position of the rotating body 12th on the axis of rotation 14 .

On that of the radiation source 22 opposite side of the rotating body 12th are radiation receivers 32 , 34 each receiving radiation, the lower half of the optical path numbered in the upper half 24th on the rotating body 12th passed by. For this purpose, the radiation that has passed is formed by means of mirrors designed as concave mirrors 33 , 35 on the small-area radiation receivers 22 , 34 focused. In the starting example shown, the radiation source can be different 22 act as a standard LED while the radiation receiver 32 , 34 can be designed in a simple manner as photodiodes. Instead of visible light, invisible wavelength ranges, for example infrared, ultraviolet, HF (high frequency) or microwaves, can also be used.

The curvatures of the mirror 23 and the mirror 33 , 35 are coordinated so that with a generally diverging optical path 24th a point image of the radiation source in the form of a fan of light 22 on the radiation receiver 32 , 34 he follows.

Another evaluation device is schematic 40 shown the measurement signals of the radiation receiver 32 , 34 receives and processes, determines rotational state variables from the measurement signals and, if necessary, the radiation source 22 controls.

From the beam divergent system of 1 a beam convergent system can be made by simple optical inversion. This is the source of radiation 22 replaced by a radiation receiver and the two radiation receivers 32 , 34 through radiation sources. The beam is now at the location of the rotating body 12th no longer divergent, but convergent.

In order to make a distinction between the upper and the lower half of the arrangement in this case as well, the radiation sources can be of different colors or be modulated differently, for example by alternating wiring or by high-frequency modulations with mutually different frequencies, which in turn can be found in a subsequent frequency analysis of the measurement signal separate from each other. The two desired measurement signals are then available as amplitude modulation on a carrier signal. The modulation speed of the carrier signal should preferably be at least twice as large as the largest frequency to be expected of the actual measurement signal and is limited by the switching speed of the radiation sources.

2nd shows for the initial example the 1 a typical course of the measurement signals in relation to the amount of light detected in arbitrary units on the vertical axis depending on the angle of rotation of the rotating body 12th , which is plotted for an angle of rotation between 0 ° and 540 °, corresponding to one and a half complete revolutions. The rotating body 12th has a 2-fold rotational symmetry, so that every single measurement signal is repeated after 180 °. For clarification, the different signal profiles in two of the three 180 ° periods are designated in order to clarify that repeating profiles each form a coherent signal profile.

With PD1 and PD2 are the direct analog measurement signals of the radiation receiver 32 or. 34 designated. These are standardized to a maximum value of 1 and fluctuate between 0 with complete coverage and 1 with minimal coverage, ie when the rotating body 12th in the representation of 1 is in its horizontal position. This is the case for the rotation angle positions 0 °, 180 °, 360 ° and 540 °. Within each individual period of 180 °, however, it can be seen that the courses of the measurement signals PD1 and PD2 are mirror-symmetrical to each other and the minimum of 0 initially in the measurement signal PD2 , in this case at approx. 68 °, and only later in the measurement signal PD1 , in this case at approx. 112 °. This is a direct consequence of the divergent expansion of the radiation field. In the event that the measurement signal PD1 from the radiation receiver 32 comes and the measurement signal PD2 from the radiation receiver 34 , it means that the body 12th themselves in the representation of the 1 counterclockwise around the axis of rotation 14 turns.

This can be explained by the fact that the rotation of the rotating body 12th in 1 from the horizontal position counterclockwise after a rotation of approx. 30 °, as in 1 shown, different parts of the divergent radiation field are shaded despite the same angular position. So is the wing of the rotating body shown on the right side 12th that protrudes into the upper half, absolutely as far from the dashed line of symmetry of the measuring system as the end of the wing of the rotating body shown on the left 12th , however, due to the greater expansion of the field, shadows a smaller proportion of the radiation in the upper half than is shadowed in the lower half. With a non-divergent beam path, the proportion of shadowed light would be the same in the upper half and in the lower half. Mirrored positions of the rotating body 12th , such as 60 ° and 120 °, could not be distinguished.

A difference signal is also shown PD1-PD2 , which is approximated in its shape to a sinusoidal shape and may therefore be easier to handle for signal processing. Furthermore, the conditions are also PD1 / PD2 and PD2 / PD1 shown, which in this case vary between approx. 0.3 and 3.5 and in turn each mirror the other in the 180 ° signal trains. These derived waveforms are highly non-linear, for the construction of the measuring system and the rotating body 12th highly characteristic and are very suitable for determining rotational state variables. Any deviation of the rotating body 12th from its central axis of rotation 14 due to vibrations or the like leads to a deviation of the measured courses from the in 2nd illustrated ideal courses and can be used for fault status determination.

3rd shows a typical time course of a measurement signal, for example the signal PD1 of the radiation receiver 32 , in the case of a slowing rotation. The horizontal axis lists sampling points and is proportional to the time course. The measurement can be carried out at a frequency of, for example, several 1000 or 10,000 samples per second. The standardized signal varies between approx. 0.03 in the minimum and 1 in the maximum. This means that even at the time of maximum shading, there is still light on the rotating body 12th passed by. After a series of approximately equally long rotation cycles, the rotation slows down approximately from the sampling point 30,000 until the rotation after the sampling point 60,000 essentially ceases entirely. Between approx. 63,000 and 80,000 there is a swinging out with a return movement and the final adjustment to the preferred position.

In the 4a) to 4d ) are different variants of devices according to the invention 10 shown schematically in cross section. These devices 10 each include rotating bodies 12th and beam divergent measuring systems 201 , 202 , 203 , 204 . This in 4a) shown measuring system 201 is very simple and contains a radiation source 22 , which emits a divergent radiation field from a point without optical deflection elements. On the other hand, in relation to a rotating body 12th are two flat radiation receivers 32 , 34 Shown above and below an axis of symmetry (dashed, without reference numerals), the part of the radiation not switched off from the radiation source 22 record, tape. This variant does not require any other optical elements and is therefore very simple.

The variant of the measuring system differs from this 202 out 4b) in that on the side of the radiation source 22 , which in this case is designed as a very small radiation source, a mirror 23 and a filter element 25th according to the Embodiment from 1 are present, which together model the distribution of the radiation field in the optical path. On the radiation receiver side, however, there are again two flat radiation receivers 32 , 34 used, so that the need for focusing on the receiving side is eliminated.

The measuring system 203 according to 4c ) is shown in the cross-sectional representation as the upper half of the divergent measuring system 20 out 1 Although a single measuring system can also be used according to the invention, a second measuring system of the same type can be used in the image plane behind the measuring system shown 203 be arranged. Due to an appealing different design of the local parts of the rotating body, that of the first measuring system 203 and the underlying second measuring system can be seen, an independent second measurement can be implemented, so that in this case too, differential measurements or measurements of ratios including phase offset are possible to eliminate ambiguities. In this respect, a second measuring system could also be at a different angle with respect to the rotating body 12th be arranged to produce a corresponding phase shift.

The divergent measuring system 204 according to 4d ) is adapted to the body of rotation 12th in this case not a grand piano 100 but has a triangular cross-section, so that a not inconsiderable part of the central beam path is always shaded. The beam path was therefore divided into an upper and a lower beam path, between which there is a gap that is slightly less wide than the permanently shaded central part of the optical path. The curvatures of the mirrors 25th , 33 , 35 are adapted to the changed geometric conditions, otherwise this arrangement corresponds to that 1 .

In 5a) to 5d ) 4 different examples of rotating bodies are shown schematically in cross section. At the in 5a) shown rotating body 12th it is an impeller 121 with two wings, that around an axis of rotation 14 , for example in the direction of the dashed arrows. For the rotating bodies of 122, 123 and 124 5b) to 5d ) are regular polygons, namely a triangle, a square and a hexagon in cross-section. Such cross-sectional shapes are very suitable, for example, as measuring sections for rotating waves in transmission and / or reflection, while the impeller 121 preferably used as a flow measuring device, for example in an impeller meter.

In the 6a) to 6d ) are different examples of rotating bodies 12th on an axis of rotation 14 shown in a frontal view. It can be an impeller, for example. In the various figures, hatched areas are opaque for the radiation used, while the non-hatched areas have reference numerals 50 marked areas are transparent or partially transparent to the radiation used. In this way, the measurement signal curve can be set favorably in order to allow an accurate and reliable determination of rotation state variables.

While in 6a) a standard arrangement with a symmetrical design of the rotor blades of the rotating body is shown, which enables an assignment of the angle of rotation within 180 °, the rotor is in 6b) designed asymmetrically to enable the rotation angle to be assigned within 360 °.

The asymmetrical impeller divided into two along its axis of rotation from the 6c ) has a combination of radiation-transmissive and radiation-opaque surfaces for each rotor blade and can in accordance with the exemplary embodiment described above 4c ) are used, for example, when two beam divergent measuring systems are decoupled from each other 203 are arranged side by side and each of them a portion of the rotating body 12th illuminate that have different transparency distributions from each other and thus to different signal profiles during the rotation of the rotating body 12th to lead. This is due to the asymmetrical design of the rotating body 12th achieve an assignment of the angle of rotation within 360 °. At the same time, optical access is only necessary in one half-plane.

In the embodiment of the 6d ) the rotor surface is designed in such a way that it is laterally irradiated, or alternatively the rotor is designed as semi-transparent without irradiating the surface, so that there is an increased permanent constant light component that can be used to compensate for disturbances in the transmission path.

The 7 and 8th schematically show two variants of devices according to the invention with convergent measuring systems 301 , 302 in schematic representations. As in 7 shown, radiates a systematically represented radiation source 22 a divergent light fan on the rotating body with a square cross section 12th . This has a rough reflecting surface, so that the radiation is scattered back with a certain distribution and onto two radiation receivers 32 , 34 meets. Both the radiation source 22 as well as the radiation receiver 32 , 34 are shown schematically. The diffusivity or specularity of the distribution of the backscatter is due to the lobe-shaped beam distributions in 7 and 8th indicated.

The radiation source 22 can be in one plane with the radiation receiver 32 , 34 be arranged, the light fan between the two radiation receivers 32 , 34 runs here. By rotating the rotating body 12th will the distribution of the reflected light on the two radiation receiver 32 , 34 change in a characteristic way so that from the measurement signal of one or both radiation receivers 32 , 34 the corresponding rotation sizes of the rotating body 12th let derive.

In contrast to the measuring system 301 are the two radiation receivers 32 , 34 in the measuring system 302 of the 8th placed next to each other and with little space. In this case too, it is a reflective arrangement, with the radiation source 22 in one on the observer of the 8th oriented direction the light source 22 above the radiation receiver 32 , 34 is arranged and its fan of light on the radiation receiver 32 , 34 diagonally downwards onto the rotating body 12th throws. The reflected light in turn hits the radiation receiver 32 , 34 .

The measuring systems of the 7 , 8th can be configured as beam-convergent measuring systems by exchanging the radiation receivers and radiation sources.

All of the features mentioned, including those that can be seen in the drawings alone and also individual features that are disclosed in combination with other features, are considered to be essential to the invention, alone and in combination. Embodiments according to the invention can be fulfilled by individual features or a combination of several features. In the context of the invention, features that are labeled “in particular” or “preferably” are to be understood as optional features.

Reference list

10th

contraption

12th

Rotational body

14

Axis of rotation

16

maximum circumferential rotation circle

20

beam divergent measuring system

22

Radiation source

23

mirror

24th

optical path

25th

Filter element

26, 26 '

Envelope

32, 34

Radiation receiver

33, 35

mirror

40

Evaluation device

50

transparent area

121

Impeller

122-124

polygonal body

201-204

beam divergent measuring system

301, 302

Measuring system in reflection arrangement

PD1

Measurement signal receiver 1

PD2

Measurement signal

Claims (15)

Device (10) for non-contact rotation measurement, comprising a rotation body (12) rotatably mounted on an axis of rotation (14) with n-fold rotational symmetry and a beam-divergent or beam-convergent measuring system (20, 201, 202, 203, 204, 301, 302), which comprises at least one radiation source (22), at least one radiation receiver (32, 34), an evaluation device (40) and an optical path (24) between the at least one radiation source (22) and the at least one radiation receiver (32, 34), in which is arranged a rotating body (12), the at least one radiation source (22) being designed to emit radiation which is divergent or convergent in the direction of the rotating body (12) onto the rotating body (12), the envelope (26, 26 ') includes a maximum circumferential rotation circle (16) of the rotating body (12), wherein a) the rotating body (12) partially shades the radiation in a transmission arrangement corresponding to an instantaneous angular position of the rotating body (12) and in which the at least one radiation receiver (32, 34) is arranged on a side of the rotating body (12) opposite the radiation source (22) and detects an unshadowed part of the radiation, and / or b) the rotating body (12) partially reflects the radiation in a reflection arrangement corresponding to an instantaneous angular position of the rotating body (12) and the at least one radiation receiver (32, 34) is arranged on the same side as the radiation source (22) relative to the rotating body (12) and detects a reflected part of the radiation, the evaluation device (40) being set up to determine at least one rotational state variable of the rotating body (12) from the quantity of the detected radiation and / or at least one variable derived therefrom. Device after Claim 1 , characterized in that the rotary body (12) is designed with n-fold rotational symmetry with 1 ≤ n ≤ 20, preferably with 1 ≤ n ≤ 10, and / or that the rotary body (12) as an impeller (121) with n blades or is formed as a regular or irregular polygonal body (122, 123, 124) with n corners and n edges in cross section. Device after Claim 1 or 2nd , characterized in that the radiation is emitted as a divergent or convergent radiation fan or as two or more diverging or converging beams. Device according to one of the Claims 1 to 3rd , characterized in that at least two radiation receivers (32, 34) are included, which are arranged to receive parts of the radiation which pass or are reflected on opposite sides of the rotating body (12), the evaluation device (40) in particular being set up forming a ratio and / or a difference in the radiation received by the at least two radiation receivers (32, 34). Device according to one of the Claims 1 to 4th , characterized in that two or more beam divergent and / or beam convergent measuring systems (20, 201, 202, 203, 204), in particular with a common evaluation device (40), are included, the two or more beam divergent measuring systems (20, 201, 202, 203, 204) are arranged at an angle to each other with respect to the rotating body (12), the two or more beam-divergent measuring systems (20, 201, 202, 203, 204) in particular being geometrically shielded from one another and / or when operating at different measuring frequencies , alternatively or additionally, are shielded from one another with frequency filters, in particular bandpass filters or edge filters. Device according to one of the Claims 1 to 5 , characterized in that in a beam-convergent system in which several radiation sources transmit radiation convergent to a single receiver, the multiple radiation sources are operated or can be distinguished from one another, in particular by clearly distinguishable modulation, by alternating radiation, or by the use and receiver side Differentiation of different wavelengths. Device according to one of the Claims 1 to 6 , characterized in that two radiation receivers (32, 34) are designed as flat radiation receivers, each of which covers part of the divergent radiation, or two, in particular symmetrical with respect to the axis of rotation (14) of the rotating body (12), combinations of each a small-area radiation receiver (32, 34) and in each case a focusing element, in particular a lens or lens combination or a focusing mirror (33, 35), by means of which a respective part of the divergent radiation is focused on the small-area radiation receiver (32, 34). Device according to one of the Claims 1 to 7 , characterized in that there are mirrors (23) which expand or bundle the radiation on the side of the radiation source (22) and / or that there are mirrors (33, 35) which are on the side of the at least one radiation receiver (32, 34) bundle or expand the parts of the radiation on both sides of the rotating body (12). Device according to one of the Claims 1 to 8th , characterized in that the rotary body (12) is at least partially partially transparent, transparent, partially reflective and / or reflective, in particular the rotary body (12) in the case of partially reflective or reflective design is reflectively reflective or roughly reflective. Device according to one of the Claims 1 to 9 , characterized in that one or more optical elements (25) for optimizing, in particular linearizing, an intensity distribution of the divergent or convergent radiation are included. Device according to one of the Claims 1 to 10 , characterized in that a device for stabilizing or referencing the light source is included, by means of which the light source is stabilized or fluctuations in the radiation intensity of the light source are compensated in the measured signals. Method for contactless rotation measurement in a device (10) according to one of the Claims 1 to 11 , wherein a divergent or convergent radiation is thrown onto the rotating body (12) of the device (10), with a) radiation passing at least one side of the rotating body (12) in at least one radiation receiver (32, 34) of the device (10) and / or b) at least part of the radiation reflected by the rotating body (12) is detected in at least one radiation receiver (32, 34) of the device, and at least one of the quantity of radiation detected and / or at least one quantity derived therefrom The rotational state variable of the rotation of the rotating body (12) is determined. Procedure according to Claim 12 , characterized in that by means of at least two radiation receivers (32, 34) radiation is detected, which has passed on opposite sides of the rotating body (12), and a difference and / or a ratio is calculated from the detected amounts of radiation, from which at least a rotational state variable of the rotation of the rotating body (12) is determined. Procedure according to Claim 12 or 13 , characterized in that an angular position, angular velocity, angular acceleration and / or direction of rotation of the rotating body (12) is determined as the rotational state variable. Procedure according to one of the Claims 12 to 14 , characterized in that deviations from regular measurements are also used to infer deviations from normal operation, in particular vibrations and / or displacements of the axis of rotation (14) or asymmetrical load.

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