In the vibration control field, in order to alleviate the vibration of controlled device, people had once proposed various controlling schemes.For example control the damping and the rigidity (damping and the rigidity that comprise bearing device) of vibration system; Adopt electromagnetic bearing or special reverse vibration exciter to carry out reverse exciting; Adopt dynamic damper to carry out weakening or the like.Two U. S. Patents are arranged, and (inventor is all ROBERT E. KEMELHOR, the patent No. is respectively US2940749 and US3059915) bearing device of a kind of being named as " fluid magnet spring, damper and locking device " that utilized characteristics design that the viscosity of magnetic fluid and rigidity become with the power of magnetic intensity, thereby change the damping and the rigidity of bearing device by regulating viscosity that exciting curent in the winding changes magnetic fluid, reach vibration damping or make bearing device obtain the rigid body of certain specific character.After magnetic intensity reached (or surpassing) certain critical value, it is very big that the viscosity of magnetic fluid and rigidity reach, and in fact is considered as body, thereby realize making the purpose of bearing device locking.The principle of these two inventions is identical.The former (US2940749) is prototype, and the latter (US3059915) is a modified model, because the uniqueness of its housing structure, allows the magnetic fluid that adopts several performances different simultaneously, thereby can improve the performance of bearing device, increases the regulation range of its damping and rigidity.They all are a kind of bearing devices of using as vibration damper, are not a kind of dynamic damper.
The big class of another of vibration control adopts dynamic damper exactly.As everyone knows, on vibrating object, install a parasitic vibration system undamped, that only form additional by spring and quality, as long as the natural frequency of this system equates with the vibration frequency of vibrating object, can eliminate the vibration (can make in theory its depressed fully) of oscillating body effectively.This spare system is exactly the dynamic damper (see figure 1) that people are familiar with.But traditional dynamic damper is unadjustable owing to its natural frequency immobilizes, and more can not carry out frequency-tracking control, and it can only be used for the changeless special occasions of vibration frequency.The occasion more common for those, that vibration frequency often changes, traditional dynamic damper does not only have good weakening effect, often can make vibration become more complicated on the contrary.This has just limited the using scope of traditional power vibration absorber greatly.
The objective of the invention is partly to replace mechanical spring in the traditional power vibration absorber with the continuously adjustable electromagnetic spring of a kind of its rigidity, regulate the electric current of field coil in the electromagnetic spring, can change the rigidity of electromagnetic spring, thereby obtain the required natural frequency identical, reach the purpose of weakening with frequency vibrating object.
Particular content of the present invention is, change traditional method for vibration, an additional mechanical spring and an electromagnetic spring on the weakening object, electromagnetic spring is made up of field coil, stator, mover, and field coil is fixed on the stator, also can be fixed on the mover, be distributed with the tooth pitch rectangle gear ring identical on the working surface of stator, mover with the number of teeth, stay an air gap between the working surface, stator and vibrating object are fixedly connected, and constitute and can be dynamically connected by bearing and mechanical spring and mover.
Below in conjunction with accompanying drawing, introduce summary of the invention in detail.
1 is vibrating object among Fig. 1, the 2nd, and vibration absorber.3 is vibration detecting sensors among Fig. 2, the 4th, and signal amplifier, the 5th, frequency discriminator, the 6th, power amplifier, the 7th, voltage to frequency switching controller.Fig. 3 is the continuous adjustable vibration absorber of electromagnetic type natural frequency that the present invention designs, and 8 is bearings among the figure, the 9th, and spring, the 10th, stop pin, the 11st, stator, the 12nd, mover, the 13rd, field coil.Stator 11 movably connects by means of two bearings 8 and two groups of springs 9 formations with mover 12.The magnetic circuit part of stator and mover is all made with good permeability magnetic material, carries out excitation by field coil 13.Leave a small air gap between the working surface of stator and mover, behind coil electricity, the magnetic line of force forms a loop by two air gaps between fixed, the mover.Owing to be evenly distributed with the identical rectangle gear ring of the facewidth, tooth pitch and the number of teeth at stator with mover working surface upper edge axial direction, can produce magnetic pull between the flank of tooth of stator and mover.The size and Orientation of this magnetic pull is relevant with the tooth deviation distance and the offset direction of stator, mover.When the tooth of stator and mover fully on time, magnetic pull is zero, this position is called stable equilibrium position.In the scope of the bias △ of stator and mover tooth S less than ± 1/4 tooth pitch T, magnetic pull increases with the increase of bias △ S, the direction of magnetic pull is then opposite with offset direction fixed, the mover tooth, and its effect is to try hard to eliminate bias fixed, mover, makes it be returned to stable equilibrium position.This is just similar with the characteristic of mechanical spring, so claim electromagnetic spring.By regulating field current, can change the spring rate of electromagnetic spring easily.Field coil 13 can be fixed on the mover, also can be fixed on the stator.The effect of two rolling bearings 8 is to allow to do relative movement vertically and keep its gap length constant between mover and the stator, and can reduce the surface friction drag between stator and the mover.The effect of mechanical spring 9 has two: 1. when vibration absorber is not worked, make stator and mover be in stable equilibrium position mutually; 2. it is in parallel with electromagnetic spring, constitutes the total spring rate of vibration absorber.The spring rate of mechanical spring should be chosen like this, and when electromagnetic spring rigidity was zero (field current is zero), the natural frequency that mechanical spring and mover quality are constituted should be equal to or slightly less than the lowest vibration frequency of controlled device.Can reduce the adjustment range of electromagnetic spring rigidity like this, simplify the design of vibration absorber, dwindle the volume of vibration absorber.The effect of stop pin 10 is to prevent to relatively rotate between stator and the mover.Fig. 4 is one embodiment of the present of invention: the straight-line oscillation vibration absorber.14 is springs among the figure.The stator of vibration absorber and the position of mover are changed mutually, are about to 11 among Fig. 3 as mover, and 12 as stator.Fig. 5 a is a vibration absorber of eliminating torsional vibration.15 is torsion springs among the figure.Fig. 5 b is that the A-A of Fig. 5 a is to view.Fig. 6 a is the another kind of embodiment who eliminates the torsional vibration vibration absorber.Fig. 6 b is that the A-A of Fig. 6 a is to view.Fig. 7 a and Fig. 7 b are two kinds of difform spring-loaded sheets of vibration absorber.Can be used for replacing bearing, mechanical spring and the stop pin of vibration absorber, integrate three's function, make mover pass through the spring-loaded sheet and movably connect with the stator formation.
When the present invention uses, should with stator be fixedly connected by weakening object 1, different according to use occasion and service condition, the mounting type of vibration absorber can adopt suspension type, and (Fig. 8 a), two vibration absorbers (Fig. 8 c) are promptly used in locating type (Fig. 8 b) or two-way weakening.
The present invention includes Fig. 3, straight-line oscillation vibration absorber shown in Figure 4 and Fig. 5, torsional vibration vibration absorber shown in Figure 6.The working principle of torsional vibration vibration absorber is identical with the straight-line oscillation vibration absorber, and only the tooth on its stator and the mover is circumferential, and spring is used torsion spring 15 instead and cancelled stop pin.
The concrete structure parameter of vibration absorber (as the size of the quality of mover, spring and quantity and distribution mode thereof, exciting watts or the like) all needs determine according to service condition, decides by dedicated calculation usually.
The present invention was implemented by the inventor, experimental results show that the weakening effect under the frequency conversion condition makes us very satisfied.
Electromagnetic type is reversed the vibration absorber embodiment:
1. utilizing one of a three-phase stepper motor to carry out the weakening of frequency conversion rate as the variable ratio frequency changer vibration absorber tests.
2. vibration absorber stator diameter (air gap place working surface diameter) φ 20mm
40 of the stator numbers of teeth
9 ° of angular pitch
Stator tooth length 20mm
Air gap 0.1mm
Maximum exciting watts 350 ampere-turns
Maximum magnetic flux moment 1200 gram-centimeters
Do not add mechanical spring
Vibration absorber natural frequency adjustment range 0~27HZ
3. experimental result:
Original vibration when not adding vibration absorber (promptly vibration absorber not being carried out excitation): excited frequency by the scope of 0~27HZ in peak swing 72 μ (arc length of measuring point).
After adding vibration absorber, peak swing is in same frequency range: 6.5 μ.
Effectively the weakening rate is: 72-6.5/72 * %=91%