A rotor angle-based expansion measurement method for spinning rotors under centrifugal stress

Abstract

In a method for measuring the expansion of a rotating rotor (5) based on the rotor rotation speed, a first distance sensor (14) is arranged at a distance from the rotor surface, the distance sensor detects the distance between the rotor surface and the first distance sensor (14) in a time-based non-contact manner and generates a time-based first electrical distance signal. A zero mark sensor (16) scans zero marks applied to the rotor (5) in a time-based manner. A second distance sensor (15) is arranged at a distance from the first distance sensor (14) in the axial direction of the rotor (5) and on a reference surface (19) whose expansion and surface profile are known. To eliminate disturbance variables, the signal detected by the second distance sensor can be offset with respect to the signal of the first distance sensor.

Description

[Technical Field]

[0001] The present invention relates to a method for measuring the rotor angle-based expansion of a spinning rotor under centrifugal stress with only one sensor, where another sensor is provided to measure the expansion of a reference surface whose expansion and surface profile is known and which is used to determine the disturbance variables. [Background technology]

[0002] When subjected to centrifugal loads, the rotor expands, i.e. the rotor diameter increases. In the simplest case, the expansion increases quadratically with the rotational speed. If one wants to know exactly how much expansion the rotor undergoes during the intended application and be able to take this expansion into account, the expansion needs to be measured while the rotor is rotating. Traditionally applied methods for determining rotor expansion only give results related to the change in rotor diameter. However, in some cases the expansion of single rotor segments is also important.

[0003] During rotor rotation, rotor vibrations can occur, which are included in the distance signal generated by the distance sensor. These rotor vibrations can be primary vibrations caused by imbalance or shock. Furthermore, vibrations can occur due to the influence of the rotor bearings, e.g., plain bearings, whose frequencies are smaller or larger than the primary vibration frequencies. Furthermore, the rotor center, around which the rotor vibrates, can shift at different speeds. The rotor is usually mounted with its axis of rotation perpendicular to the plain bearing and can therefore move laterally and assume different stable points at different rotational speeds. The aforementioned influences, and in particular the speed-dependent shifts of the rotor shaft, are known as disturbance variables or disturbance vibrations and, by being superimposed on the measured distance signal, affect the accuracy of the measurement results.

[0004] Gunther, P. et al.: Measuring the Radial Expansion and Tumbling Motion of a High-Speed ​​Rotor Using an Optical Sensor System. Mechanical Systems and Signal Processing, Vol. 25 (2011), pp. 319-330. A method for measuring the radial expansion and tumbling motion of a rotor rotating at high speed using an optical sensor system is known. The sensor system includes three laser Doppler distance sensors positioned at the same height and angular position along the circumference of the rotor, each at an angular distance of 120° from the rotor and from each other. To determine the precise angular alignment of the three distance sensors, optical marks that trigger sensor signals are attached to the rotor. The time delay between the trigger signals of the three sensors is used in relation to the rotation frequency to determine the precise angular distance of the sensors. During measurement, the electrical output signals of the sensors are sampled at a sampling rate matched to the rotor rotation speed and set to reach a certain number of measurement points per rotor revolution, depending on the rotation frequency. Then, at each sampling step, the center of mass and radial expansion are calculated by solving a system of linear equations, and finally, the average value of the radial expansion for the rotor, assumed to be a cylindrical measurement object, is calculated from a number of consecutive measurement points, where the rotor expansion is not determined as a function of the rotation angle.

[0005] DE 101 44 643 A1 describes a measurement system having multiple distance sensors connected to the stator of a rotor-stator system and arranged on the rotor for non-contact measurement, in which two pairs of distance sensors are arranged at symmetrical positions to detect the radial distance between the stator and the rotor. To determine the rotor displacement, measurement signals of a pair of distance sensors with opposite signs are added. To determine the rotor's radial expansion, measurement signals of all four distance sensors with positive signs are added. No means for detecting the rotor expansion related to the rotation angle are provided.

[0006] DE 102013 110 632 B4 discloses a method for measuring rotor expansion by means of two distance sensors whose distance signals are precisely offset from one another. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Patent DE 101 44 643 A1 [Patent Document 2] German Patent DE 102013 110 632 B4 Specification [Non-patent literature]

[0008] [Non-Patent Document 1] Gunther, P. et al.: Measurement of radial expansion and tumbling motion of a high-speed rotor using an optical sensor system. Mechanical Systems and Signal Processing, Vol. 25 (2011), pp. 319-330 Summary of the Invention [Problem to be solved by the invention]

[0009] The invention is therefore based on the object of presenting a method for measuring the expansion of a rotating rotor as a function of the rotor rotation speed, in which the interfering variables that occur can be easily eliminated. [Means for solving the problem]

[0010] This object is achieved by the features of claims 1 and 5. Preferred embodiments are presented in the dependent claims.

[0011] According to the present invention, an object is to provide a method for measuring the expansion of a rotating rotor based on the rotor rotation speed, wherein a first distance sensor is disposed at a base distance from the rotor surface, and detects the distance between the rotor surface and the first distance sensor in a time-based non-contact manner, and generates a time-based first electrical distance signal; a zero mark sensor is assigned to the rotor, scanning a zero mark applied to the rotor to generate a time-based electrical zero mark signal; the time-based first electrical distance signal and the time-based electrical zero mark signal are supplied to an electrical evaluation device and processed by calculating from the time-based zero mark signal a rotation speed and a rotation angle assigned to each instant of rotor rotation; each rotation angle assigned to a certain instant is combined with a simultaneous distance signal to form a rotation angle-related distance signal, from which a rotor expansion dependent on the rotation angle and the rotation speed is calculated; a second distance sensor is disposed on a first reference surface, the first reference surface having a known expansion and surface profile, at a base distance from the first reference surface, the second distance sensor detects the distance of the first reference surface from the second distance sensor in a time-based non-contact manner, and generates a time-based second electrical distance signal, which is supplied to an electrical evaluation device; A third distance sensor is arranged on another second reference surface, spaced apart from the first and second distance sensors in the axial direction of the rotor, at a basic distance from the second reference surface, the expansion and surface profile of which are known, and the third distance sensor detects the distance between the second reference surface and the third distance sensor in a time-based non-contact manner to generate a time-based third electrical distance signal which is supplied to the electrical evaluation device, and the electrical evaluation device processes the second and third electrical distance signals to correct the first distance signal detected by the first distance sensor so that after subtracting the known expansion and surface profile of the surface from the second distance signal and the third distance signal, any remaining interfering vibrations are geometrically proportionally removed from the first distance signal of the first distance sensor by trigonometry.

[0012] According to the present invention, an object is also to provide a method for measuring expansion of a rotating rotor based on rotor rotation speed, wherein a first distance sensor is disposed at a base distance from a rotor surface, and detects a distance between the rotor surface and the first distance sensor in a time-based non-contact manner, and generates a time-based first electrical distance signal; a zero mark sensor is assigned to the rotor, scanning a zero mark applied to the rotor to generate a time-based electrical zero mark signal; the time-based first electrical distance signal and the time-based electrical zero mark signal are supplied to an electrical evaluation device and processed by calculating from the time-based zero mark signal a rotation speed and a rotation angle assigned to each instant of rotor rotation; each rotation angle assigned to a certain instant is combined with a simultaneous distance signal to form a rotation angle-related distance signal, from which a rotor expansion dependent on the rotation angle and the rotation speed is calculated; A second distance sensor is arranged at a base distance from the rotor surface, spaced apart from the first distance sensor in the axial direction of the rotor, on a rotor surface whose expansion and surface profile are known, and the second distance sensor detects the distance of the reference surface from the second distance sensor in a time-related, non-contact manner, and generates a time-related second electrical distance signal which is supplied to an electrical evaluation device and processed therein, thereby correcting the first distance signal detected by the first distance sensor, so that after subtracting the known expansion and profile of the surface from the second distance signal, any interfering vibrations remaining therein are geometrically proportionally removed from the first distance signal of the first distance sensor by trigonometry and the known pivot point of the rotor.

[0013] A third distance sensor is arranged at a base distance from the first reference surface, and detects the distance of the surface from the third distance sensor in a time-related, non-contact manner, and generates a time-related third electrical distance signal to supply to an electrical evaluation device, whereby the tilt or gradient of the rotor is removed as a disturbance variable by offsetting the second distance signal and the third distance signal, and disturbance vibrations remaining in the second distance signal from the first distance signal of the first distance sensor are removed from the second distance signal, so that the rotor tilt can be taken into account in that it is geometrically determined as an interference variable and removed with the correct weighting from the rotor expansion signal.

[0014] The invention makes it possible to determine, for each point on the track of the rotor surface recorded by the measurement, the expansion of the rotor caused by centrifugal force and dependent on the rotation speed, determined by the angle of rotation relative to the zero point, taking into account any disturbance variables.

[0015] Since the expansion measurement is also performed on a reference surface with known expansion, the disturbance variables can be determined in a simple manner simultaneously with the actual distance measurement and subtracted from the distance measurement on the rotor. This allows for simple measurements with only a few sensors and can be performed quickly. Known measurement methods require the use of two sensors per rotor measurement track. In contrast, the method according to the present invention requires only one sensor per measurement track. For the purposes of the present invention, the reference surface can be a part, section, or area of ​​the rotor.

[0016] The reference surface can also be a part, component or area that can be connected to the rotor, has a known expansion and can be, for example, screwed to the rotor or fixed in another way. It can be a reference component with at least one reference surface, such as a reference pin. The expansion of the reference surface can be predetermined by a separate measurement or can be negligibly small due to the nature of the surface.

[0017] If bearing isotropy is not provided, it can be advantageous to provide that at least one additional, in particular fourth and fifth, distance sensors are provided, arranged at a base distance from one of the reference surfaces and detect the distance of the surface from the fourth distance sensor in a time-dependent, contactless manner and generate a time-dependent fourth electrical distance signal which is supplied to the electrical evaluation device, the fourth distance sensor being arranged, together with another of the distance sensors arranged on the reference surface, at a different circumferential angle (preferably 90° or less) to the second and third sensors already introduced, so that its effects can be taken into account accordingly.

[0018] The invention will now be explained in more detail with reference to embodiments illustrated in the drawings. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic diagram of a device for measuring the expansion of a rotating rotor. [Figure 2] FIG. 1 shows a schematic measurement setup with two reference surfaces. [Figure 3] FIG. 1 shows a schematic measurement setup with one reference surface. DETAILED DESCRIPTION OF THE INVENTION

[0020] FIG. 1 shows an exemplary device for high-speed spinning and rotor expansion measurement, illustrating one possible application of embodiments of the present invention. The device comprises a cylindrical protective enclosure 1 that receives and encloses the rotor during measurement operations. The protective enclosure 1 can be closed with a cover 2, the upper side of which houses a gearbox 3 with a shaft 4 located outside the protective enclosure 1. The shaft 4 is guided through the cover 2 and has a flange for fixing the rotor 5 to be measured underneath. The shaft 4 is driven by an electric motor 6 connected to the gearbox 3 by a belt drive 7. The cover 2 is attached to the arm 8 of a hydraulic lifting unit 9, which allows the lid 2 to be lifted from the protective enclosure 1 and placed on it. The hydraulic controls for the lifting unit 9 are housed in a housing 10 located on the frame of the lifting unit 9. The sealed protective enclosure 1 can be evacuated by a vacuum pump 11 to avoid drive losses and excessive heating inside the enclosure. An electric control unit 12 serves to control the electric motor 6 , the lifting unit 9 and the vacuum pump 11 .

[0021] To measure the expansion of the rotor 5, a non-contact measuring distance sensor 14 can be mounted on the cover 2 at a short distance from the rotor surface. Another distance sensor 15 can be placed at a distance from the component shown diagrammatically with a reference surface (in this case a pin). This arrangement is also shown diagrammatically in Figure 3.

[0022] Furthermore, a zero point sensor 16 is arranged on the cover 2 adjacent to the exposed part of the shaft 4, which scans the zero mark on the shaft 4. Since the rotor 5 is fixedly connected to the shaft 4 by means of a flange, the scanning of the zero mark also applies to the rotor 5. The distance sensors 14, 15 and the zero point sensor 16 are connected by lines (not shown) to an evaluation device 17 which includes a computer programmed with an evaluation program. The distance sensors 14, 15 generate analog voltages which are converted into digital distance signals at the input of the evaluation device 17. The voltage signal of the zero point sensor 16 is also digitized.

[0023] To measure the expansion of the rotor 5, the cover 2 is placed on the protective container 1 by the lifting unit 9. This brings the rotor 5 and the distance sensors 14, 15 inside the protective container 1, where a measurement run can be carried out by the control unit 12. In the measurement run, the rotor 5 is driven by the electric motor 6 via the gearbox 3 and the shaft 4 and rotated at different rotational speeds.

[0024] In one embodiment, several reference runs can be performed at low speed at the start of the measurement, which serves to determine the basic distance between the two distance sensors 14, 15. The rotor 5 is then accelerated to a very high rotational speed to measure the expansion. At a constant rotational speed, the distance signals of the two distance sensors 14, 15 and the zero mark signal of the zero mark sensor 16 are simultaneously detected and supplied to the evaluation device 17, where they are processed on a time basis. An essential advantage of the present invention is that measurements can also be performed during startup, which in turn is associated with time savings.

[0025] The evaluation device 17 uses the zero mark signal to calculate the rotational angle reference of the distance signal, and in embodiments where measurements are made at a constant speed, can calculate an average value from the distance signal measured over several rotor revolutions. When measuring at start-up, a magnification of the angle relative to the rotational speed can be output.

[0026] Here, the evaluation device 17 receives angle-related, specifically averaged, distance signals from each of the two distance sensors 14, 15. The distance signal from the distance sensor 14 includes a measured distance that is related to the rotation angle and dependent on the expansion of the rotor 5, which in turn depends on the rotation speed and the rotation angle. The distance signal also includes a basic distance that is independent of the rotation speed and additional disturbance variables. The same applies to the distance signal determined by the distance sensor 15. To calculate the expansion, the distance signal from the reference surface is subtracted from the distance signal from the rotor measurement track. The proportional subtraction can depend on the geometric ratio of the measurement track positions, which can be determined using trigonometry. As a result, interference signals that also occur on the reference surface are eliminated.

[0027] FIG. 2 shows a schematic measurement setup with two reference surfaces, while FIG. 3 shows a schematic measurement setup with a reference component in the form of a reference pin. As already explained in the example above, the rotor 5 is connected to the drive shaft via a flange 18. Between the rotor 5 and the flange 18, there can be an area, referred to in the present invention as a reference surface or reference area, whose expansion and surface profile under centrifugal stress are known. This can also be a separate reference component that can be connected to the rotor 5, such as a reference pin 19 with a reference surface or multiple reference surfaces that is screwed to the rotor 5. Depending on the design of the rotor 5 or its attachment to the measurement device, the rotor 5 can be positioned between the two reference pins 19, 20 in one or more enclosures. In contrast, only one reference pin 19 is shown in FIG. 3.

[0028] A zero point sensor 16 is provided to detect a zero mark, for example on a flange 18. Furthermore, a distance sensor 14 for detecting a distance signal without contact is arranged at a distance from the rotor. Furthermore, a second distance sensor 15 can be provided to detect a distance signal between a reference pin 19 and the sensor. In the illustrated embodiment, a third distance sensor 21 is arranged at a distance from a second reference pin 20.

[0029] 3, in addition to the first distance sensor 14 and the reference element 19 with at least one reference surface, only the second distance sensor 15 is provided. In this case, after subtracting the known expansion and profile of the surface from the second distance signal detected by the second distance sensor 15, the remaining disturbance vibrations can be geometrically removed from the first distance signal of the first distance sensor 14 using trigonometry and the known pivot point of the rotor 5. This also makes it possible to take into account the tilt or inclination of the rotor 5.

[0030] The tilt can also be taken into account by eliminating it as a disturbance variable by offsetting the second distance signal and the third distance signal and removing any disturbance vibrations remaining in the second distance signal from the first distance signal of the first distance sensor 14.

[0031] In other words, the method according to the invention allows the elimination of interference components that occur during the measurement of the rotor angle-related expansion of a rotating rotor under centrifugal stress, using only one sensor (given a known pivot point) or at least two additional sensors that detect distance signals on a reference surface or surfaces with known geometry and expansion relative to the rotation speed and offset these by distance signals from the rotor detected by the distance sensors. The design of the measurement setup is simple, and interference components can be easily eliminated, since only one sensor per measurement level is required, with one or two additional sensors being needed to record disturbance variables. Furthermore, thanks to the method according to the invention, transient measurements of expansion during start-up are also possible.

[0032] To further reduce the influence of interference or to improve the accuracy of the triangulation, additional distance sensors can be provided on other reference surfaces, whose measurements are essentially taken into account as described above.

[0033] Another advantage of the present invention is that if the expansion and geometry of the reference surface with respect to rotational speed are known (e.g., perfect circle), then 1F features (e.g., grooves) do not affect the determination of expansion in the rotor 5. However, known methods require complex 1F filtering to be performed. [Explanation of symbols]

[0034] 1 Protective container 2 Cover 3 Gearbox 4 shafts 5 rotors 6 Electric Motor 8 Arm 9 Lifting Unit 10. Housing 11 Vacuum pump 12 Electrical control unit

Claims

1. A method for measuring the expansion of a rotating rotor (5) based on the rotor rotation speed, comprising: A first distance sensor (14) is arranged at a basic distance from the rotor surface to detect non - contact, in a time - based manner, the distance between the rotor surface and the first distance sensor (14), and generates a time - based first electrical distance signal; A zero - mark sensor (16) is assigned to the rotor (5), scans a zero - mark applied to the rotor (5), and generates a time - based electrical zero - mark signal; The time - based first electrical distance signal and the time - based electrical zero - mark signal are supplied to an electrical evaluation device (17), which is processed by calculating the rotation speed and rotation angle assigned to each instant of rotor rotation from the zero - mark signal. Each rotation angle assigned to an instant is combined with the simultaneous distance signal to form a rotation - angle - related distance signal, from which the expansion of the rotor (5) depending on the rotation angle and the rotation speed is calculated; A second distance sensor (15) is arranged at a basic distance from a first reference surface (19) which is spaced apart from the first distance sensor (14) in the axial direction of the rotor (5) and has a known expansion and surface profile. The second distance sensor detects non - contact, in a time - based manner, the distance of the reference surface (19) from the second distance sensor (15), generates a time - based second electrical distance signal, and supplies it to the electrical evaluation device (17); A third distance sensor (21) is arranged at a basic distance from a second reference surface (20) which is spaced apart from the first and second distance sensors (14, 15) in the axial direction of the rotor (5) and has a known expansion and surface profile. The third distance sensor detects the distance between the reference surface (20) and the third distance sensor (21) non - contact in a time - based manner to generate a time - based third electrical distance signal which is supplied to the electrical evaluation device (17). The electrical evaluation device (17) processes the second and third electrical distance signals to correct the first distance signal detected by the first distance sensor (14). After subtracting the known expansion and surface profile of the surface from the second distance signal (15) and the third distance signal (21), the remaining interference vibrations are geometrically proportionally removed from the first distance signal of the first distance sensor (14) by triangulation.

2. In addition to the known expansion and profile of the surface, by offsetting the second and third distance signals to remove them as interference variables, the inclination or gradient of the rotor (5) is also taken into account, and the remaining interference vibrations in the second distance signal from the first distance signal of the first distance sensor (14) are removed from the second distance signal. The method according to claim 1, characterized in that.

3. At least one additional, in particular a fourth distance sensor is provided, the fourth distance sensor being arranged at a basic distance from one of the reference surfaces (19, 20), detecting the distance of the reference surface (19, 20) from the fourth distance sensor non - contact in a time - related manner to generate a time - related fourth electrical distance signal which is supplied to the electrical evaluation device (17). The fourth distance sensor is arranged at a different angle in the circumferential direction with respect to the second and third distance sensors (15, 21) together with another distance sensor (15, 21) arranged on the reference surface (19, 29). The method according to claim 1, characterized in that.

4. A further distance sensor is provided on a further reference surface. The method according to claim 1, characterized in that.

5. A method for measuring the expansion of a rotating rotor (5) based on the rotor rotation speed, The first distance sensor (14) is arranged at a basic distance from the rotor surface to detect non - contact, on a time - basis, the distance between the rotor surface and the first distance sensor (14), generating a time - based first electrical distance signal, The zero - mark sensor (16) is assigned to the rotor (5) and scans a zero - mark applied to the rotor (5), generating a time - based electrical zero - mark signal, The time - based first electrical distance signal and the time - based electrical zero - mark signal are supplied to an electrical evaluation device (17) and processed by calculating the rotational speed and the rotational angle assigned to each instant of rotor rotation from the zero - mark signal. Each rotational angle assigned to an instant is combined with the simultaneous distance signal to form a rotation - angle - related distance signal, from which the expansion of the rotor (5) depending on the rotational angle and the rotational speed is calculated, A second distance sensor (15) is arranged at a basic distance from a reference surface (19) which is spaced apart from the first distance sensor (14) in the axial direction of the rotor (5) and has a known expansion and surface profile. The second distance sensor non - contact detects, in a time - related manner, the distance of the reference surface (19) from the second distance sensor (15), generating a time - related second electrical distance signal which is supplied to the electrical evaluation device (17) and processed to correct the first distance signal detected by the first distance sensor (14). After subtracting the known expansion and profile of the surface from the second distance signal, the remaining interference vibrations are geometrically proportionally removed from the first distance signal of the first distance sensor (14) by means of triangulation and the known pivot point of the rotor (5). Method.

6. The method according to claim 1 or 5, characterized in that an average value is formed from a plurality of reference operations at low rotational speeds to determine the basic distance of the distance sensors (14, 15, 21).

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