METHOD FOR DETERMINING VIBRATION BEHAVIOR OF AN ELECTRIC MOTOR AND/OR OF ITS INSTALLATION ENVIRONMENT, AND CORRESPONDING ELECTRIC MOTOR AND FAN

Abstract

A method is disclosed for determining a vibration behavior of an electric motor, in particular an electric motor of a fan, and/or its installation environment, wherein a rotary motion of a rotor of the electric motor can be braked in a braking process. The disclosed method comprises: generating a jolt by triggering a braking process or an acceleration process or by changing a braking process or an acceleration process, generating detected vibration values by detecting vibrations of at least a part of the electric motor by means of at least one vibration sensor, determining spectral components by means of a frequency analysis of the detected vibration values, and determining a vibration behavior of the electric motor and/or its installation environment by evaluating the spectral components.

Further disclosed is a corresponding electric motor, fan, and system, each of which may be configured to carry out the method.

Claims

1. A method for determining a vibration behavior of an electric motor, in particular an electric motor of a fan, and/or its installation environment, wherein a rotary motion of a rotor of the electric motor can be braked in a braking process, comprising: generating a jolt by triggering a braking process or an acceleration process or by changing a braking process or an acceleration process, generating detected vibration values by detecting vibrations of at least a part of the electric motor by means of at least one vibration sensor, determining spectral components by means of a frequency analysis of the detected vibration values, and determining a vibration behavior of the electric motor and/or its installation environment by evaluating the spectral components.

2. The method according to claim 1, wherein generating a jolt by means of a braking process comprises bringing the rotor to an initial speed and triggering a braking process to reduce a speed of the rotor from the initial speed to a final speed over a braking time.

3. The method according to claim 1, wherein when determining the vibration behavior, one or more resonance points are determined and their criticality is evaluated, wherein the presence of a resonance point is decided if one of: a spectral component exceeds a predetermined limit; and if detected vibrations are dominated by an order of an evaluation frequency.

4. The method according to claim 1, when determining the vibration behavior, at least one type of vibration is determined, wherein the at least one type of vibration comprises at least one of tilting, wobbling, torsion, and axial pumping.

5. The method according to claim 1, wherein synchronization is performed between the jolt and the generation of detected vibration values, wherein the synchronization is performed by at least one of: motor electronics of the electric motor; and by detection of a peak in a sensor signal of the at least one vibration sensor.

6. A method according to claim 1, wherein the vibrations of at least a part of the electric motor are detected along at least one axis.

7. The method according to claim 1, wherein rapid braking is performed during the braking process.

8. The method according to claim 2, wherein the generation of detected vibration values is started when at least one of: the braking process is triggered; and the final speed is reached.

9. The method according to claim 2, wherein the initial speed is one of: greater than or equal to 100 revolutions per minute and greater than or equal to 200 revolutions per minute, and wherein the initial speed is one of: less than or equal to 30% of the rated speed of the electric motor; less than or equal to 20% of the rated speed of the electric motor and less than or equal to 10% of the rated speed of the electric motor.

10. The method according to claim 2, wherein the final speed is one of: less than or equal to 50 revolutions per minute; less than or equal to 25 revolutions per minute and equal to 0.

11. The method according to claim 2, wherein the braking time is chosen to be one of: less than or equal to 10 seconds; less than or equal to 5 seconds; and less than or equal to 3 seconds.

12. The method according to claim 1, wherein at least one of a Fourier transform and a G?rtzel algorithm is used to generate spectral components.

13. An electric motor configured to perform a method according to claim 1, comprising: a rotor which is mounted for rotating about an axle/shaft, a jolt generating device for generating a jolt by triggering a braking process or an acceleration process or by changing a braking process or an acceleration process, a vibration sensor configured to detect vibrations of at least part of the electric motor and to generate detected vibration values, an analysis unit configured to determine spectral components of the detected vibration values, and an evaluation unit configured to evaluate the vibration behavior by evaluating the spectral components.

14. The electric motor according to claim 13, wherein the vibration sensor is integrated in the electric motor or arranged on an outside of a housing of the electric motor and/or in that the vibration sensor is arranged in an electronics housing of the electric motor.

15. The electric motor according to claim 13 further comprising motor electronics which controls the electric motor during its operation, wherein the motor electronics uses a determined vibration behavior to control the electric motor and thereby preferably avoids speeds of the electric motor with unfavorable vibration behavior.

16. A fan, configured to perform a method according to claim 1, comprising an impeller and an electric motor according to claim 12, wherein the impeller is coupled to a rotor of the electric motor.

17. A system comprising an installation environment and a drive, wherein the drive comprises an electric motor according to claim 13 and a fan according to claim 15, wherein the installation environment interacts with the drive, and wherein the drive is configured to detect and evaluate both vibrations of the drive and vibrations of the installation environment.

18. A method according to claim 6, wherein the vibrations of at least a part of the electric motor are detected along multiple axes, wherein the at least one axis or one of the multiple axes is arranged parallel to an axis of rotation of the rotor.

19. The method according to claim 7, wherein the rapid braking is short circuit braking.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0051] FIG. 1 shows a sectional view of an embodiment of an electric motor according to the present disclosure,

[0052] FIG. 2 shows a flowchart showing steps of an embodiment of a method according to the present disclosure,

[0053] FIG. 3 shows a diagram with exemplary time data of detected vibration values along a z-axis, and

[0054] FIG. 4 shows a diagram with a frequency analysis of the time data according to FIG. 3.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0055] FIG. 1 shows a section through a stator 2 of an embodiment of an electric motor 1 according to the present disclosure. A bearing tube 4 is formed on a motor axle 3, and a bearing mounting area 5 is formed at each of its longitudinal ends. Bearings not shown are accommodated in the bearing mounting areas 5, via which a shaft of the electric motor, also not shown, is rotatably mounted. A stator bushing 6 is formed by an aluminum component, at one end of which the bearing tube 4 is formed and at the other end of which an electronics housing 7 is formed to accommodate motor electronics. The motor electronics respectively generates supply signals and outputs them to the stator and/or rotor windings. For the sake of clarity, only one printed circuit board 8 of the motor electronics is shown. A vibration sensor 9 is arranged on the printed circuit board 8. The printed circuit board 8 is embedded in a potting compound 10, 11, wherein the potting compound 10, 11 is bonded to the edge region of the printed circuit board 8. In particular, the potting compound 10 acts as a coupling element and transmits vibrations from the stator bushing 6 to the printed circuit board 10 and thus to the vibration sensor 9. As a further coupling element, a screw 12 is provided which is screwed into a hole 13 in the electronics housing 7. In this way, the vibration sensor 9 can be arranged in an electric motor and detect vibrations of at least a part of the electric motor. Such an electric motor may be used in the method disclosed herein.

[0056] FIG. 2 shows a flowchart of an exemplary embodiment of a method according to the present disclosure, wherein in this embodiment example a brake shock is triggered. In step S1, the rotor is brought to an initial speed. This initial speed is, for example, 200 revolutions per minute. In step S2, a braking process is initiated which brakes the rotor of the electric motor from the initial speed to a final speedin this case, standstill of the rotor. In step S3, vibrations of at least a part of the electric motor are detected by means of a vibration sensor, and detected vibration values are generated. The vibration sensor 9 of the electric motor according to FIG. 1 can be used here. In step S4, spectral components are determined by subjecting the acquired vibration values to a frequency analysis, for example an FFT. In step S5, the vibration behavior of the electric motor and/or its installation environment is determined. For this purpose, the determined spectral components are evaluated.

[0057] FIG. 3 shows an exemplary curve of a time signal of a vibration sensor, wherein an acceleration value (in m/s.sup.2) for a vibration parallel to the motor axle/motor shaft is shown over time (in seconds). At the beginning, vibration values are measured which result from the rotary motion of the electric motor at the initial speed. At time t.sub.Bapproximately after 2.3 seconds in the time scale showna braking process is initiated which leads to a braking peak 14. In the following approx. 1.4 seconds, the rotor is decelerated such that the rotor comes to a standstill at time t.sub.Sat approx. 3.7 seconds. The standstill leads to a standstill peak 15. To determine the vibration behavior, the vibration values from the standstill peak 15 are detected and evaluated as an example.

[0058] FIG. 4 shows spectral components of the time signal according to FIG. 3 from the standstill peak 15. An amplitude of the spectral component (in m/s.sup.2) is plotted against the frequency (in Hertz). It can be seen that in addition to a peak at a frequency of 0 Hertz, three distinct peaks are formed: at about 27 Hertz, at about 35 Hertz, and at about 58 Hertz. From this, potential resonance points can be identified. If it is assumed that each resonance point is a first-order resonance point, this theoretically results in critical speeds at 1620 rpm, 2100 rpm, and 3480 rpm. With an electric motor that can rotate at a maximum of 2400 rpm, for example, at most the first two speed values mentioned can be problematic. The third resonance point may exist, but in a practical operation it can only be relevant for a higher order excitation.

[0059] For further advantageous embodiments and to avoid repetition, see the general part of the description above and the appended claims.

[0060] Finally, it should be expressly noted that the exemplary embodiments described above are only used to explain the claimed teaching but do not limit this teaching to these exemplary embodiments.

LIST OF REFERENCE SYMBOLS

[0061] 1 Electric motor [0062] 2 Stator [0063] 3 Motor axle [0064] 4 Bearing tube [0065] 5 Bearing mounting area [0066] 6 Stator bushing [0067] 7 Electronics housing [0068] 8 Circuit board [0069] 9 Vibration sensor [0070] 10 Potting compound [0071] 11 Potting compound [0072] 12 Screw [0073] 13 Hole [0074] 14 Brake peak [0075] 15 Standstill peak