CN201262589Y - Pneumatic vibration isolator for optical platform - Google Patents

Abstract

The utility model discloses a pneumatic vibration isolator used for an optical platform, including an external constraint skirt, an internal constraint skirt, and a rubber diaphragm positioned between the external constraint skirt and the internal constraint skirt. The pneumatic vibration isolator is characterized in that: the external constraint skirt or the internal constraint skirt expands from bottom to top to form a cone tube, the inclination angle Theta of which is 20 degrees. Compared with the existing straight tube constraint, due to the straight tube constraint, the effective area of the rubber diaphragm is not changed when moving, while in the inclined tube constraint, as the external (or internal) constraint skirt is the cone tube expanding upwards, the effective pressure bearing area of the internal constraint skirt is reduced when moving downwards, namely, the change rate of the effective pressure bearing area is less than zero, and the air spring stiffness can be reduced due to the spring stiffness caused by the change of the effective pressure bearing area, thus achieving the effect of reducing the inherent frequency.

Description

The pneumatic vibration isolator that is used for optical table

Technical field

The utility model relates to a kind of isolation mounting, especially relates to a kind of pneumatic vibration isolator.

Background technology

The requirement of Experiments of Optics system accuracy and stable aspect, make to detect and experiment work must be at a highly stable accurate operation platform with good anti-vibration performance---carry out on the optical table.Any small vibration, walking about caused vibration etc. as the caused vibration of the pulsation of the earth, people on the floor all can be to detecting and test findings exert an influence.

Along with scientific-technical progress, the application of optical table is from traditional balance, beam split, interference, holography, be extended to modern large scale integrated circuit, electric physiology, Neurobiology and biological physiology, and in fields such as Aeronautics and Astronautics, national defense and military, obtained using widely, more and more higher to the requirement of vibration isolation.Therefore, the method for improving the vibration isolator performance is studied always hardy by the manufacturers of optical table, and hope can reduce the natural frequency of optical table to greatest extent, improves vibration isolation efficiency.Hot research in recent years is the ACTIVE CONTROL optical table with good low frequency performance, but owing to active vibration isolation system stability and poor reliability, involve great expense, thereby the optical table active Vibration Isolation still has significant limitation at present, and can not be used widely.

Summary of the invention

Technical problem to be solved in the utility model provides a kind of pneumatic vibration isolator that is used for optical table, and this pneumatic vibration isolator can reduce the natural frequency of optical table, and can improve vibration isolation efficiency.

For solving the problems of the technologies described above, the technical solution adopted in the utility model is as follows:

A kind of pneumatic vibration isolator that is used for optical table comprises outer constraint skirt, interior constraint skirt, the diaphragm of rubber between outer constraint skirt and interior constraint skirt, is characterized in: retrain outward that skirt is expanded from bottom to top or interior constraint skirt shrinks formation circular cone tube from bottom to top.The angle of inclination of circular cone tube is θ=20 °.

The utility model is compared with existing straight tube constraint, because straight tube constraint, rubber diaphragm its effective pressure area when motion is indeclinable; And tiltedly tube constraint, because outer constraint skirt is to be the circular cone tube that upwards shrinks with down with upwards expansion or interior constraint skirt, thereby its effective pressure area minimizing when interior constraint skirt moves down (being equivalent to length of spring compressed), promptly the effective pressure area rate of change is less than＜0.The spring rate that effective pressure area causes when changing can make air spring rigidity reduce, thereby reaches the effect that reduces natural frequency.

Another characteristics of the present utility model are: only change existing vibrating isolation system structural parameters a little, just reach the effect that reduces natural frequency, and simple.

Description of drawings

Fig. 1 is the utility model structural representation;

Fig. 2 is a natural frequency---the relative damping factor graph of a relation.

Embodiment

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

The utility model course of work is as follows:

The utility model is a kind of, and to be used for the pneumatic vibration isolator of optical table actual be an air spring of being made up of the air chamber 4 and the rubber diaphragm 2 of certain pressure, air spring is to utilize the compressibility of air to realize a kind of nonmetal spring of elastic vibration, thereby reaches the purpose of separating vibration.

The utility model mainly is made up of outer constraint skirt 1, interior constraint skirt 3, rubber diaphragm 2 (elastomeric material by softness is made, and the shape during work depends on the shape of inside and outside constraint skirt 1,3), air chamber as shown in Figure 1.Form a kind of inclination restraining structure between outer constraint skirt 1, interior constraint skirt 3, the rubber diaphragm 2, promptly outer constraint skirt 1 expand from bottom to top or interior constraint skirt 3 shrinks formation circular cone tube 6 from bottom to top, and the angle of inclination of circular cone tube 6 is θ=20 °.

The air chamber 4 of sealing is connected with the auxiliary chamber 5 of certain pressure, makes air chamber keep certain pressure.Because the constraint skirt is oblique tube, so claim that tiltedly tube retrains membrane type.

The variation characteristic of rubber diaphragm 2 its effective pressure area when distortion depends on the shape of inside and outside constraint skirt 1,3.

Bear load weight on the interior constraint skirt 3, when air chamber 4 was full of pressure air, aerostatic buoyancy was floated to the equilibrium position load.

Under static state, the effective bearing area A of the pressure p of air chamber 4 and rubber diaphragm 2 multiplies each other long-pending, equals the weight of rubber diaphragm 2 upper support load, i.e. p * A=W.

Under motion state, the basis of imagining whole device produces displacement or interior constraint skirt 3 (or the load on it) suddenly and is subjected to the external force effect, rubber diaphragm 2 produces flexible, its air plenum 4 internal volumes and rubber diaphragm 2 effective bearing areas all change, thereby make the load on the rubber diaphragm 2 produce motion because of stressed effect.Meanwhile, produce pressure differential between air chamber 4 and the auxiliary chamber 5, portion of air flows to the low side of pressure from the high side of pressure, and wherein portion of energy becomes heat energy, and motion obtains decay.

The constraint type of structure shown in Figure 1 makes rubber diaphragm 2 useful area rate of change less than 0, and the spring rate that the effective pressure area rate of change causes has reduced the rigidity of system, reaches to reduce the optical table natural frequency, improves the purpose of its anti-vibration performance.

Embodiment: retrain skirt 1 outward and make the upwards circular cone tube 6 of expansion, its angle of inclination is θ=20 °.Effective carrying radius r=4.8 * 10 of air spring ^-2M; Gas meter pressure: p=4.4 in the air spring * 10 ⁴Pa; During rubber diaphragm 2 motions, the rate of change of its useful area is:

$\frac{\mathrm{dA}}{\mathrm{dx}}=-\frac{1}{r}\frac{\sin \mathrm{\&theta;}}{1+\cos \mathrm{\&theta;}+\frac{1}{2}(\mathrm{\&pi;}+\mathrm{\&theta;})\sin \mathrm{\&theta;}}\&times;A=-0.02{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="Y200820152611E00072.png"\; state="\{\{state\}\}">m</figure-callout>}}^2/m,$ Then the relevant spring rate of useful area rate of change is ${\mathrm{<figure-callout\; id="2"\; label="K"\; filenames="Y200820152611E00072.png"\; state="\{\{state\}\}">K</figure-callout>}}_2^{\&prime;}=p\frac{\mathrm{dA}}{\mathrm{dx}}=4.4\&times;{10}^4\&times;(-0.02)=-8.8\&times;{10}^{2}N/m.$

By calculating result shown in Figure 2, Fig. 2 solid line is represented straight tube constraint skirt (θ=0 °) natural frequency---relative damping factor result of calculation, dotted line are represented tiltedly tube constraint skirt (θ=20 °) result of calculation.As can be seen, under all identical situation of other parameters, when adopting θ=20 a ° oblique tube to retrain skirt, because useful area changes the spring rate of item $K_{}^{}$ ${}_2^{\&prime;}<0,$ Can reduce the natural frequency of vibrating isolation system, when relative damping factor ≈ 0.1, natural frequency approximately can descend 0.3.

Claims (2)

1. pneumatic vibration isolator that is used for optical table, comprise outer constraint skirt (1), interior constraint skirt (3), be positioned at the rubber diaphragm (2) between outer constraint skirt (1) and the constraint skirt (3), it is characterized in that described outer constraint skirt (1) is expanded from bottom to top or interior constraint skirt (3) shrinks formation circular cone tube (6) from bottom to top.

2. the pneumatic vibration isolator that is used for optical table according to claim 1 is characterized in that, the angle of inclination of described circular cone tube (6) is θ=20 °.

Images