• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    In a method for determining unbalance compensation of resilient shaft rotors (1), the rotor (1) is rotatably housed in two bearing devices. A speed sensor (4) measures the speed of the rotor (1) and a radial movement of the rotor (1) is measured at different rotational speeds of the rotor by means of displacement sensors (3) at measuring points (6) during an unbalance measurement cycle or during several unbalance measurement cycles. The entered measurements are transmitted to an operating unit (5) which determines the eccentricity values corresponding to the measuring points (6) by means of an extension of the influence coefficient method, so that unbalances by plane and eccentricities per measuring point are determined for each cycle. Figure for the abstract: Fig. 1
    公开号:FR3077638A1
    申请号:FR1901097
    申请日:2019-02-05
    公开日:2019-08-09
    发明作者:Kai (Dr.) Trukenmüller
    申请人:Schenck RoTec GmbH；
    IPC主号:
    专利说明:

    Description
    Title of the invention: Method for measuring the unbalance of rotors with elastic shaft using displacement sensors The invention relates to a method for determining the unbalance of rotors with elastic shaft using displacement sensors at points of measurement whose eccentricity with respect to the bearing surface of the rotor is unknown.
    To balance rigid rotors, it is generally sufficient to apply correction masses in two axially separated planes. The correction masses, and therefore also the rotor unbalance, are independent of the operating speed. The balancing speed can be freely chosen. It is often chosen to be as low as possible and is often lower than when used later. On the other hand, in the case of rotors with elastic shaft, the concept of unbalance must be generalized. The number of planes required can be more than two and the axial position of the planes is of great importance. Whether a rotor can be considered rigid or an elastic shaft depends not only on the mechanical properties of the rotor, but also on its operating speed. The more the operating speed increases, the more important the elastic properties play.
    Document DE 41 33 787 A1 discloses a balancing process for elastic rotors which, without a test mass cycle, determines the correction masses necessary to balance the unbalance of the rigid body and the deflections of the rotor with elastic shaft. First, at least one unbalance measurement is determined during an unbalance measurement cycle at a speed at which the rotor exhibits behavior with a rigid body. At least one other unbalance measurement is determined per bearing plane and per mode suitable for correcting at a speed situated in the zone of the modal speed to be taken into account. The unbalance correction is calculated in an operating unit using the unbalance measurements obtained and characteristic data specific to the rotor or the bearing to compensate for the rigid body unbalance and the proper mode component to be taken into account, a force footprint, independent of speed and constant, being calculated for each bearing plane, which also describes the unbalance effect of the elastic rotor. In this process, it is necessary to enter the specific characteristic data of the rotor and of the bearing, such as the data of dimension, shape and material used of the rotor to be balanced.
    Document DE 40 19721 A1 describes a balancing method for an elastic rotor which operates at or near critical speeds, with a correction in three or more correction planes and the use of combinations of general unbalance distributions of the rotor and predetermined eigen modes, without actually balancing the rotor at critical speeds. During an unbalance measurement cycle at low rotational speed, corrections are usually determined which are made in two rotor correction planes. In addition, a third correction is made on the rotor which is proportional to the first and to the second correction and to the unbalance / form of mode combination. After another low-speed unbalance test cycle, which serves as the test mass cycle for the third correction, corrections are again determined for the first and second correction plan and used for the final balancing of the rotor. This balancing process does not make it possible to minimize the maximum admissible correction masses nor to minimize the admissible residual unbalance values.
    The unbalance measurement is often carried out indirectly by the vibration of the frame. This means that we measure the vibrations which are transmitted by the shaft to the fixed structure of the frame via bearings. The vibrations of the frame are generally measured by acceleration sensors (eg piezoelectric vibration sensors) or by vibration speed sensors. In particular for balancing installations at high speed or in the event of balancing in service of the rotors of power stations, such as turbines or generators, displacement sensors are also used which measure directly the radial movement of the shaft instead of the vibrations of the frame. The displacement sensors are for example capacitive or inductive displacement sensors (eddy current sensors) or laser triangulation sensors. In flexible bearings such as leaf or air bearings, the bearing gap is large relative to the eccentricity of the center of gravity of the rotor subjected to unbalance. The rotor rotates around its axis of inertia, which rotates eccentrically in the bearings. The forces transmitted to the surrounding structure (eg the frame) by the flexible bearings are relatively small. This has the consequence that it is certainly possible to measure with the aid of displacement sensors the axis of rotation extending eccentrically, but the vibrations transmitted to the structure are however too weak for an accurate determination of the unbalance by measurement. vibrations of the frame. The effect will be enhanced if the frame is relatively heavy compared to the rotor. This is particularly the case for units that have small rotors and a relatively large frame (for example with input and output lines or stator windings for an electric drive or generator).
    The influence coefficient method is a method of calculating the unbalance which is based on measurement cycles with known unbalances (eg reference work by W. Kellenberger; Elastisches Wuchten, Berlin 1987, pages 317-325). It is mainly used to measure the unbalance of rotors with elastic shaft. For this, it is assumed that there is a linear relationship between the applied unbalances and the oscillatory responses at the measurement points. The test unbalance per plane is noted as a complex number, where the amplitude and the angle of the complex number correspond respectively to the amplitude of the unbalance and to the angular position on the rotor. For each test cycle, the vibrations are measured if possible in several positions and at several speeds. The measurement can also be taken when the rotor is started, then assigned to fixed speeds or speed intervals. The type of measurement (e.g. acceleration at bearing positions or measurement of the radial position of the shaft using displacement sensors) is not important for the formulation of the influence coefficient method. From the time series of sensor values, the first order is evaluated in relation to the current rotation frequency. This requires a speed or angle sensor that measures a mark on the rotor. A complex number is also formed from the signal amplitude and the phase of the vibration sensors relative to the speed sensor. The relationship between the unbalance and the vibration signal can then be described using a system of linear equations with complex numbers:
    [0007] [Math.l]
    S - [0008] Here, 5 is the vector of the complex amplitudes of the signal. It contains the values of all the sensors and speeds used. It therefore has the length N = (number of speed support points) x (number of sensors). The unbalances are gathered by plane of unbalance in the vector of unbalances u. For P unbalance planes, u has the length P. The matrix of the influence coefficients K has the dimension N x P. Both 5 and K and u are complex quantities.
    The influence coefficients method can be solved, for example, by determining the matrix K. This is generally done by P + l test cycles, where a known single unbalance is applied to each cycle in a plane of different imbalance. In addition, it is possible to carry out a cycle without test mass, a cycle which is called the initial cycle (Urlauf). Then the matrix K of the influence coefficients is determined by subtracting the initial cycle from all the other test cycles. However, this is only one of the possible methods for determining K.
    When K is known, it is possible to calculate the unbalance in all planes for any cycle of the rotor. This is done by solving the system of linear equations according to the unknown unbalance vector u. In general, there are more measurement points N than unknown unbalances P, so that the system of equations is overdetermined. In this case, it can be solved using the linear correction calculation (least squares method).
    However, there are other methods which solve the system using optimization methods and, where appropriate, additional boundary conditions. Once the system has been resolved, the imbalances u are generally compensated in each plane, for example by the application of counterbalances or by removal of material. The vibration can then be measured again and, if necessary, the rotor can be balanced in additional steps.
    If displacement sensors are used in the influence coefficient method, the objective is then to reduce the bending of the shaft caused by the unbalance. This becomes problematic if the measuring point on the rotor, where the bending is measured, already has eccentricity without rotation, for example due to a bent shaft or an impact on the measuring surface. Significant errors can be generated if eccentricity errors are ignored and the influence coefficient method is applied according to the known method. In this case, the constant measurement error is interpreted as the vibratory displacement of the shaft which must be compensated for by balancing.
    The objective of the invention is to provide a method of measuring unbalance in which an eccentricity in at least one measurement point is taken into account.
    This object is achieved by a method for determining an unbalance of rotors with elastic shaft by means of displacement sensors at measurement points which have an unknown eccentricity with respect to the bearing surfaces, method in which the rotor is housed. rotatable in bearings, a speed sensor measures the rotor speed, a radial movement of the rotor is measured by means of displacement sensors at measuring points during an unbalance measurement cycle or during several unbalance measurement cycles at different rotational speeds of the rotor, the measurements entered are transmitted to an operating unit, the operating unit using the measurements entered to solve a system of equations which, in addition to the unbalance, includes the unknown eccentricity, so that the imbalance per plane and the eccentricity per measurement point are calculated. Using the method according to the invention, it is possible to determine the eccentricity of the measurement point during the unbalance measurement cycle proper and to take it into account when calculating the unbalance. This means that no separate measurement cycle is necessary to determine a possible eccentricity at low speed.
    The unbalance values corresponding to the measurement points can, for example, be determined by extending the method of the influence coefficients. However, other optimization methods can also be used. If the measurement points have unknown eccentricities, these are contained in the complex amplitudes of the signal in the form of errors. The system of equations of the method of influence coefficients can be advantageously extended by [Math.2] s = K ii 4- E e [0017] where e is the vector of the unknown eccentricities. The length of the vector is equal to the number of measurement points. The matrix E consists only of zeros and ones. There is only one in each column. It is located in column number k, which corresponds to the measurement point of this line:
    with 1 if signal s t from the sensor at the position, otherwise 0.
    lo, [0018] The extension of the influence coefficient method can be formulated as follows:
    [Math.3] s - 4 λ [0020] For this purpose, the two KetE matrices can be written next to each other as follows:
    [Math.4]
    A = [ALE] at A.
    The vector x can include unknown imbalances and eccentricities.
    [Math.5]
    The determination of the matrix of the influence coefficients K can be carried out according to the known method of the influence coefficients. As differences are always formed, the basic eccentricity has no influence. In one embodiment, the extended influence coefficient method can be used to calculate the unbalance for any measurement cycle.
    It is preferable that the unbalance is measured in a speed range in which the rotor has elastic deviations. When balancing at low speed, it is not always possible to rotate the rotor around the axis that the component will occupy in the subsequent mounting of the rotor. This can be disadvantageous during subsequent operation of the rotor, since even small eccentricity errors are sufficient to cause significant unbalance values on the mounted rotor. In a preferred configuration, balancing takes place in a speed range in which the rotor already has an elastic shaft behavior. This simulates the normal operation of a rotor system rotating at high speed and balances the rotor at speeds up to service speed.
    To measure the unbalance, it may be preferable to accelerate the rotor to predefined measurement speeds. This makes it possible to accurately determine the effects of a rotor unbalance and, for example, a test unbalance at a desired speed.
    It may be advantageous if the measurements are made during acceleration or deceleration of the rotor, so that it is not necessary to carry out other test cycles and that the balancing can be done effectively.
    It may also be preferable to determine the unbalance and the eccentricity in the service speed range of the rotor. In this case, the rotor is accelerated to a speed which advantageously lies at its service speed or at least close to its service speed. With elastic shaft rotors precisely, balancing at low speed is not satisfactory. On the other hand, with the preferred embodiment of the method, the rotor is accelerated at speeds within its operating speed range, so that the unbalance is measured in a speed range which reflects the actual operation of the rotor and which allows a reliable balancing.
    In a preferred embodiment, the rotor is housed in flexible bearings. Rigid bearings are often used to transmit unbalance vibrations to the frame and to measure them. For certain rotor systems, it is however advantageous, even necessary, to use flexible bearings. Thanks to the preferred embodiment of the method, in which the rotor is housed in flexible bearings and the measurement is carried out using displacement sensors, the previous measurement methods can be considerably improved and the eccentricity can be determined by more unbalance.
    It may be advantageous to measure vibrations at other measurement points by means of a sensor element. In the case of vibration transmission, vibration sensors can be used in addition to displacement sensors, the measurements of which can be used to solve the system of equations.
    The invention is explained in more detail below using an embodiment of the invention shown in the figure. Figure [fig.l] shows a rotor in an unbalance measuring device.
    Figure 1 schematically shows an unbalance measuring device in which a driven rotor (1) has bearing surfaces (2) and is housed, for example, in two bearings. The rotor (1) can also be housed in more than two bearings. The bearings can be flexible bearings, such as leaf bearings or air bearings. Two displacement sensors (3) measure radial movements of the rotor (1), that is to say its bending. A speed and angle sensor (4) measures a mark on the rotor (1). The measurements captured by the sensors (3, 4) are transmitted to an operating unit (5).
    Displacement sensors (3) are used which determine an eccentricity of at least one measurement point (6), or of a measurement surface, which has an unknown eccentricity with respect to the bearing surfaces (2 ). Due to the soft bearings, no significant vibration occurs which could be used to calculate the unbalance. If necessary, additional sensors can be used to measure for example a vibration of the frame or a vibration of the foundations, which in turn can be used to calculate the unbalance.
    The present method can be used advantageously when the measurement of the eccentricity cannot be carried out at the positions of the bearings because the bearings are closed or inaccessible. It is also possible to take the measurements directly next to the bearings, at a point which has only a slight eccentricity with respect to the bearing. However, this is only possible if the bearing positions are accessible to the displacement sensors (3). However, the rotor (1) is generally designed to be as compact as possible. Therefore, it may not be possible to place sensors at bearing positions, particularly in the case of small units, due to spatial constraints. However, it is possible to easily measure the imbalance of compact rotor systems thanks to the preferred method and the placement of the displacement sensors (3) on measurement points whose radial eccentricity is unknown relative to the bearing surfaces (2) .
    A drive device for the unbalance measurement device accelerates the rotor (1) at appropriate speeds, the drive device can also be controlled so that it is possible to preset fixed balancing speeds . The measurements to be entered can also be entered in normal operation, so that, for example, when accelerating the rotor (1) at balancing speeds which can be preset, the corresponding measurements are entered and transmitted to the unit. operating (5). The rotor (1) can also be accelerated at speeds which lie within its operating speed range.
    It is possible with the method of balancing rotors (1) having any number of balancing planes. Often, balancing plans are imposed by design, as in turbochargers or turbine rotors, and allow only a maximum allowable balancing mass for reasons of size or strength.
    The rotor (1) is accelerated to a preset rotational speed n at which it exhibits the behavior of a rotor with an elastic shaft. When the preset speed n is reached, the sensors (3, 4) take measurements and transmit them to the operating unit (5). The measurement can also be carried out at several rotational speeds n.
    In the case where the eccentricity error of the measurement points (6) relative to the bearing surfaces (2) is known, it can be taken into account mathematically in the measurement signals and the known method of influence coefficients can, for example, be used to calculate the unbalance. However, it is not always possible to measure eccentricity. The bearings are generally no longer accessible in the assembled state. When the measurement is made before mounting, it is not possible to guarantee that eccentricity errors will be retained during mounting. Often, the eccentricity of the measurement surface (6) is determined at low speed and the measured values are subtracted from the measurements at high speed (so-called runout compensation / runout compensation). However, this only works with rigid bearings, such as roller bearings. In the case of hydrodynamic plain bearings, different axes of rotation (orbits) often occur at different speeds of rotation, so that an eccentricity error cannot be unequivocally defined. Other bearings, for example leaf bearings, need a minimum speed to be able to operate stably. In such cases, it is often not possible to slowly rotate the rotor. It is accelerated very quickly to the minimum speed of rotation which is beyond the natural frequencies of the rigid body of the rotor-bearing system. Using the method according to the invention, the unbalance measurement can be easily carried out taking into account the eccentricity of such rotor systems. An unbalance of elastic shaft rotors (1) can be determined by means of displacement sensors (3) on measuring points (6) having an unknown eccentricity with respect to the bearing surfaces (2), the rotor (1) being rotatably housed in bearings, the speed sensor (4) measuring the speed of the rotor (1), a radial movement of the rotor (1) being measured by means of displacement sensors (3) at measuring points (6) during a measurement cycle or several unbalance measurement cycles at different rotor speeds, and the captured measurements being transmitted to an operating unit (5), the operating unit (5) using the entered measurements to solve a extension of the influence coefficients method according to the system of equations, with vector 5 which includes measures and velocities, with
    =. [K E.
    with the matrix of influence coefficients K of dimension, v .... "and the matrix
    r Ί and with 1 if J lo, signal from the sensor at the position, otherwise 0, with the vector x including the unbalances and eccentricities unknown with
    , so that for each measurement cycle it is possible to determine unbalances per plane and eccentricities per measurement point. A central idea of the process is that the eccentricity, in addition to the unbalance to be determined, is contained as an unknown in the system of equations, the system of equations being able to be solved by optimization methods. The use of an extended coefficients of influence method is only a preferred embodiment.
    The method has proved particularly advantageous for rotor systems rotating at high speed in small units such as electric compressors, vacuum cleaner motors, pumps or micro gas turbines. In these systems, the rotor is often housed in flexible bearings, such as air, gas, foil or magnetic bearings. With the method according to the invention, it is possible to measure the unbalance and to determine the eccentricity, the displacement sensors advantageously measuring the bending of the rotor shaft outside the bearing positions.
    权利要求:
    Claims (1)
    [1" id="c-fr-0001]
    claims
    Method for determining an unbalance of elastic shaft rotors (1) by means of displacement sensors (3) at measurement points (6) whose eccentricity with respect to the bearing surface (2) is unknown, in which the rotor (1) is rotatably housed in bearings, a speed sensor (4) measures the speed of the rotor (1), a radial movement of the rotor (1) is measured by means of displacement sensors (3) measurement (6) during an unbalance measurement cycle or during several unbalance measurement cycles at different rotational speeds of the rotor, the captured measurements are transmitted to an operating unit (5), the operating unit using the measurements entered to solve a system of equations which, in addition to the unbalance, includes the unknown eccentricity as unknown, so that the unbalance by plane and the eccentricity by measurement point are calculated.
    Method according to claim 1, characterized in that the measurement is carried out in a speed range in which the rotor (1) has elastic deviations.
    Method according to claim 1, characterized in that the rotor (1) is accelerated at predefined measurement speeds.
    Method according to claim 1, characterized in that the measurements are taken when the rotor (1) is accelerated or decelerated. Method according to claim 1, characterized in that the unbalance and the eccentricity are determined in the operating speed range of the rotor (DProcess according to one of the preceding claims, characterized in that the rotor (1) is housed in flexible bearings.
    Method according to one of the preceding claims, characterized in that vibrations are measured at other measuring points by means of a sensor element.
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    法律状态:
    2020-02-20| PLFP| Fee payment|Year of fee payment: 2 |
    2020-11-27| PLSC| Publication of the preliminary search report|Effective date: 20201127 |
    2021-02-17| PLFP| Fee payment|Year of fee payment: 3 |
    2022-02-21| PLFP| Fee payment|Year of fee payment: 4 |
    优先权:
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    DE102018102751.6A|DE102018102751B3|2018-02-07|2018-02-07|Method for measuring the imbalance of wave-elastic rotors by means of distance measuring sensors|
    DE102018102751.6|2018-02-07|
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