Vibration measurement and analysis in Elevator traction machine.
A constant velocity drive at the no-load condition with the elevator car speed at 1.00 m/sec and an acceleration driving test at the no-load condition with the elevator car speed changing from 0 to 2.00 m/sec are carried out. The acceleration of the housing and the noise level in the front 1 m position of the elevator traction machine are measured. Figure shows the experimental setup.
The test is carried out with the upper part of the elevator traction machine supported from two points by a chain block and the lower part elastically supported with isobutylene-isoprene rubber. The noise is measured by a 1/2-inch microphone (B&K and used 4190-C). In the driving acceleration test, the elevator car accelerated from 0 to 2.00 m/sec, and the maximum pressure level is measured by peak hold. The other measurement devices are the same as those used in the excitation test.
5.2 Constant Speed
Figure shows the axial vibration of the results of the test and calculation at constant speed in the center of the housing sidepiece. Figure shows the pressure level of the test and calculated pressure level at constant speed in the front 1 m position of the elevator traction machine. Each calculation result is a response analyzed with the time order ingredient of the electromagnetic force for the frequency of the driving current. Several similar tendencies such as the acceleration level of time order 2 maximum and pressure levels of time order 6 and 12 dominant are shown in Figures 2 and 3. This shows that this analysis technique is appropriate. It is thought that the natural frequency error of the analysis and measurement influence the error in the analysis and measurement.
5.3 Acceleration Drive
For elevator car speed acceleration from 0 to 2.00 m/sec, for example, the frequency of time order 6 of the electromagnetic force changed from 0 to 880 Hz, and eigenmodes (An eigenmode is a natural vibration of a system such that various parts all move together at the same frequency. The different parts all move sinusoidally at the same frequency and their amplitudes all increase or decrease in proportion to one another.) in the frequency band are excited.
Fig-2
Fig-3(sound and pressure level at constatnt speed)
Therefore it is thought that the eigenmodes influence the vibration and noise at the time of the acceleration. This is evaluated by the noise, because it is difficult to measure acceleration of moving rotor and sheave. Figure -4 shows the sound pressure level of the test and calculation results at constant speed in the front 1 m position of the elevator traction machine. Figure-4 shows that the analysis is sufficient to simulate the test. The eigenmode at which the noise level radiated from the elevator traction machine maximum in the frequency band of 1000 Hz or less is the housing mode of 791 Hz. In addition, the eigenmode of the rotor, which has a damping ratio at 536 Hz of 0.1%, had a large contribution to the radiated noise.
Reducing radiated noise by these eigenmodes makes it possible to build a low-noise elevator traction machine. Therefore, calculations are carried out to study the correlation between these eigenmodes and space order s of excitation force by using the force of a single space order as the excitation force. Figure-4 shows the relation between the axial acceleration level of the housing sidepiece at a housing mode of 791 Hz and a space order of excitation force s, and Figure-5 shows the relation between the axial acceleration level of the rotor sidepiece at the rotor and sheave mode of 536 Hz.
Figures -5 show that the acceleration level of each eigenmode changed in every space order of excitation force. In particular, the excitation force of space order 2 had a large contribution to the acceleration level, so considering the relation between eigenmodes and space order s of the excitation force makes it possible to grasp the change of noise level of 1000 Hz or less when the structure of the elevator traction machine changes.
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