Influence of main machine’s basic vibration frequency
The vibration rate is F=N/60, of which N is the rated speed of the main machine.
For elevators with gears, the vibration frequency is greater than 20-30HZ, the impact is obvious, mainly for the feeling of shaking feet; but for elevators without gears, the frequency is mostly between 2-5HZ, if the car vibration is relatively large (such as single-frequency corresponding amplitude of more than 4MG), there will be a feeling of car, that is, low-frequency. The chatter (guide rail Boot Shoe friction excitation) also causes a similar phenomenon.
According to experience, for a gearless elevator with acceptable elevator performance, if the corresponding amplitude of the upper base is mostly within 2.5 MG, the human body may feel jitter, but it is acceptable; if the corresponding amplitude of the fundamental frequency is within 1.0 MG, there is basically no sense of vibration.
The influence of (magnetic steel) polar logarithm
At this time, the vibration frequency of the car is shown as the rated frequency of the motor: N/60*P is the extreme logarithm.
Case: Six OH5000 MRL, 630KG, 1.0M/S, the main vibration frequency of the sedan is 19HZ. The amplitude of the frequency corresponding to the serious section is about 12MG, the vibration A95 value of the sedan is about 35MG. The foot shaking feeling is serious when the human body rides.
The main machine has a rotating speed of 95R/MIN and a pole number of 12, so that the rated frequency of the motor is 95/60*12=19HZ, which is consistent with the vibration frequency in the car.
For this kind of vibration problem, it is suggested to conduct in-depth analysis of electromagnetic field factors to find the root.
Factors related to rolling bearings
At this time, the vibration frequency of the car is shown as N/60 * ball number (or even one of them), which can also be said to be reflected in a certain frequency doubling of the basic vibration frequency of the main machine; in addition, frequency doubling phenomenon is generally common under impact conditions. And the impact of the ball and the inner and outer rings of the bearing is basically in line with this condition, that is to say, the frequency doubling phenomenon caused by the impact may also occur in the working condition of the rolling bearing.
Elevator vibration in a business center (OH5000, 1000KG, 2.5M/S) is mainly reflected in the fundamental frequency 4HZ (motor speed 239R/MIN, corresponding rotation frequency 4HZ) and its order frequency doubling. This phenomenon, on the one hand, may be caused by the main machine excitation frequency-car/spring suspension system frequency close to the resonance, on the other hand, may also be related to the working conditions of rolling bearings.
Effect of static balance or dynamic balance on main machine
At present, the second main machine of 007 has done dynamic balance test, it is said that there are improvements: whether the dynamic balance has a great impact on the vibration in the car can be judged according to the elevator performance after the main machine is installed.
Influence of main air gap
The air gap should be uniform during the idling of the main machine, and some changes may occur after the load is suspended. For example, the noise problem of the improved OH5000MRL in early 2006 (highlighting the peak frequency, 818HZ), mainly with the mainframe
The air gap is related. The impact of this change on the vibration and noise of elevator is analyzed.
- The theoretical model of air gap can be established to analyze the effect of air gap on the magnetic field (magnetic field strength, magnetic force, etc.). The influence of air gap on the mechanical structure of tractor (shaft) can be transmitted to the car through the tractor-wire rope.
- If possible, the change of air gap during loading can be tested. The test results can be analyzed by structural theory and actual elevator vibration.
- Measures to reduce vibration of main machine
- Establish the factory standard of tractor by controlling the vibration amplitude (twist vibration, vertical vibration, etc.). To control from the source. The specific criteria specified in the standard should be determined on the basis of a large number of empirical data.
- By improving the whole ladder isolation system, enhancing the resistance of the elevator system to the main machine.