CN100451377C - Linear anti-deflection double-chamber air-spring - Google Patents

Abstract

The invention relates to a linear anti-swing dual-chamber air spring, used in the vibration insulation of accurate test table, or the like. The invention is characterized in that the lower part of piston via the maze seal is engaged with the seal of compressing ring; the middle of piston and the compressing rind form the air bearing to avoid traditional rubber seal. The invention uses maze seal or magnetic fluid seal to replace the rubber seal, to eliminate the effect on the natural frequency and damping character of air spring. And the membrane uniform function of air bearing of piston can hold the piston at the center of cylinder to eliminate the effect of eccentric installment of piston and load, to avoid vibration. And the invention can avoid the elastic effect of rubber, to obtain the dual-chamber air spring with low natural frequency.

Description

Linear anti-deflection double-chamber air-spring

Technical field

The present invention relates to a kind of pneumatic spring, be mainly used in the vibration isolation of equipment such as ultraprecise test stand, ultra-precision machine tool and optical table, belong to ultraprecise equipment and measurement technique field.

Background technique

In ultraprecise processing, IC manufacturing and optically detecting process, can reach its final performance by harm equipment from outside and inner vibration, so the equipment in these fields extensively adopts various vibration isolators to reach the purpose that excludes vibration, wherein simple and reliable, with low cost and excellent performance has obtained using widely pneumatic spring with it, it can form the hybrid type vibration isolator with other active vibration isolation, also can use separately.The structural type of pneumatic spring mainly contains two kinds of single chamber and dual cavity, wherein double-chamber air-spring is owing to its natural frequency does not change with the load quality size, realize structural decoupling zero, and in ultraprecise test stand, ultra-precision machine tool and optical table field, obtained a large amount of application.

Existing double-chamber air-spring general structure is cylindrical or the external form of square column type, and be divided into upper chamber and lower chambers by stationary barrier, process the throttle orifice of some on the fixing dividing plate according to actual needs, the upper chamber top is connected with circular piston by ring-shaped rubber.Load or outside vibration cause the piston up-down vibration during work, and upper chamber's pressure changes and impels air flowing between the chamber up and down, and flow air is given birth to damping through the miscarriage of throttle orifice time, reaches the purpose of eliminating vibration amplitude.

Double-chamber air-spring is to produce damping by air through the throttle orifice between last/lower chambers.The dynamic analysis of the type air cushion shock absorber all has discussion in various documents, these documents are mainly derived its transmissibility formula by the fluid continuity equation:

$\frac{x_p\left(s\right)}{x_{\mathrm{base}}\left(s\right)}=\frac{\frac{n{P}_0{A}_p^2}{V_{t0}}(s+\frac{n{P}_0{C}_r{n}_0}{V_b})}{m_p{s}^3+\frac{m_{p}n{P}_0{C}_r{n}_0(V_{\mathrm{<figure-callout\; id="0"\; label="t"\; filenames="C20071006264000071.png"\; state="\{\{state\}\}">t</figure-callout>}0}+V_b)}{V_{t0}{\mathrm{<figure-callout\; id="2"\; label="V\; b\; s"\; filenames="C20071006264000072.png"\; state="\{\{state\}\}">V</figure-callout>}}_b}{s}^{}{}^2+\frac{n{P}_0{A}_P^2}{V_{t0}}s+\frac{n^2{\mathrm{<figure-callout\; id="0"\; label="P"\; filenames="C20071006264000071.png"\; state="\{\{state\}\}">P</figure-callout>}}_0^2{n}_0{C}_r{A}_P^2}{V_{t0}{V}_b}}$

Constant wherein $C_r=\frac{\mathrm{\&pi;}{d}^4}{128\mathrm{\&mu;l}};$ Air viscosity constant μ=1.824E-5Pa*s; P ₀=chamber initial pressure up and down; m _p=load

Quality; A _p=piston area; V _b=lower chambers volume; V _T0=upper chamber initial volume; Changeable constant n=1.4; n ₀=throttle orifice number; L=throttle orifice length; D=throttle orifice diameter;

The pneumatic spring performance itself is a nonlinear problem, can cause the performance of theory analysis and actual air spring to have very big gap like this.Most research documents are pointed out non-linear turbulent flow and the rubber seal parts that mainly come from air, and in order to solve nonlinear problem, common solution mainly concentrates on and reduces the non-linear factor that turbulent flow brings:

1) smooth and do not have sun to block thing in the chamber.

2) orifice structure is level and smooth and thickness is little.

3) increase throttle orifice quantity, allow air flows be similar to laminar flow.

4) the big displacement of restriction load, the magnitude that common commercial double-chamber air-spring piston stroke is 10 μ m.

And for rubber bring non-linear, be difficult to carry out effective theory analysis usually, the theoretical formula of pneumatic spring does not comprise the factor of rubber in most documents.Because rubber can be regarded a spring damping element as, spring that it is bigger and damping constant all have great influence to the natural frequency and the transmissibility of pneumatic spring, cause the result of result such as actual natural frequency and resonance peak and theoretical formula estimation to have very big difference, simultaneously because the elasticity of rubber and the existence of damping factor, can cause pneumatic spring can't accomplish extremely low natural frequency, the pneumatic spring natural frequency is minimum in the world at present can only accomplish about 0.5 to 1Hz, can't further realize lower natural frequency.

In addition, there is an important defective in pneumatic spring, second resonance peak as shown in Figure 1, this is because piston or load setting-up eccentricity can cause the beat vibration of air-spring piston, eliminate this vibration and have only by meticulous debuging with one heart just and can achieve the goal, but thisly debug the time-consuming industrialization manufacturing that is unfavorable for piston.

Summary of the invention

The objective of the invention is in line with eliminating rubber seal effect of non-linear of bringing and the beat vibration problem that suppresses owing to piston/load placed off-centre is brought, a kind of linear anti-deflection double-chamber air-spring is provided, to eliminate rubber seal effect of non-linear of bringing and the beat vibration that suppresses owing to piston/load placed off-centre is brought, further improve the functional structure of double-chamber air-spring, make the accurately dynamics problem of this pneumatic spring of computational analysis of the theoretical formula that proposes in the various documents.

The objective of the invention is to be achieved through the following technical solutions:

A kind of linear anti-deflection double-chamber air-spring, contain cylinder body, piston, be arranged on the cylinder body top and the trim ring that cooperates in piston and be arranged on dividing plate in the cylinder body, this dividing plate is separated into upper chamber and lower chambers with inner chamber of cylinder block, it is characterized in that: described lower part of piston is sealed and matched by noncontact seal and trim ring; Middle of piston and trim ring constitute pneumatic bearing, this pneumatic bearing comprises the radially auxiliary hole that is distributed on trim ring middle part, opens at the throttle orifice of auxiliary hole end and the annular groove that is connected with described auxiliary hole, this annular groove top seal ring seal, and on arbitrary auxiliary hole, valve is installed.

The noncontact seal that the bottom of piston described in the present invention cooperates with trim ring can adopt labyrinth seal or magnet fluid sealing.

On the basis of technique scheme, of the present invention piston-shaped be circular or square; And be provided with limiting board on the top of piston.

The present invention compared with prior art, have the following advantages and the high-lighting effect: 1. the present invention has replaced rubber seal by labyrinth seal or magnet fluid sealing, eliminated the very big influence of rubber to pneumatic spring natural frequency and damping characteristic, therefore can carry out analyses and prediction to the performance of pneumatic spring by theoretical derivation formula fully, it is theoretical and the actual result difference is very little.2. the present invention is by the air film homogenization of pneumatic bearing on the piston, makes piston remain at the center of cylinder, eliminated the setting-up eccentricity problem of piston and load, avoided the beat vibration.3. pneumatic spring of the present invention has been got rid of the stiffness effect factor of rubber, therefore can design the extremely low air cushion shock absorber of natural frequency fully.4. pneumatic spring environmental suitability of the present invention is strong, and still the working pressure air is as power, applicable to other such as fields such as ultra-precision machine tool, optical tables.

Description of drawings

Fig. 1 is theoretical transmissibility result of calculation of existing pneumatic spring and measured drawing.

Fig. 2 is the main sectional view of linear anti-deflection double-chamber air-spring provided by the invention.

Fig. 3 is the structural representation of trim ring among the present invention.

Fig. 4 is the axis side view of piston among the present invention.

Among the figure: the 1-piston; The 2-trim ring; The 4-O RunddichtringO; 5-first valve; The 8-dividing plate; The 9-cylinder body; The 12-base plate; The 13-lower chambers; The 14-throttle orifice; 15-upper chamber; 16-first seal ring; 17-second seal ring 17; The 18-limiting board; 20-air-bearing working surface; 21-labyrinth seal blade; 22-air-bearing throttle orifice; The internal surface of 25-trim ring bottom; The 26-auxiliary hole; The 27-annular groove; 28-second valve; 29-trim ring upper inside surface.

Embodiment

Below in conjunction with accompanying drawing principle of the present invention, concrete structure and working procedure are further described.

Fig. 2 is a linear anti-deflection double-chamber air-spring embodiment's provided by the invention main sectional view.This linear anti-deflection double-chamber air-spring, contain cylinder body 9, piston 1, be arranged on the cylinder body top and the trim ring 2 that cooperates in piston and be arranged on dividing plate 8 in the cylinder body, the throttle orifice 14 of some has been arranged at dividing plate 8 middle parts, and this dividing plate is divided into upper chamber 15 and lower chambers 13 with inner chamber of cylinder block; When piston 1 up-down vibration, cylinder body 9 pressure inside air will flow between upper chamber 15 and lower chambers 13 back and forth by throttle orifice 14 like this, produce throttle resistance when pressure air passes through throttle orifice 14, thereby reach the purpose of attenuation vibration.

The bottom of piston 1 is sealed and matched by noncontact seal and trim ring 2, preferably adopts labyrinth seal or magnet fluid sealing.Middle of piston and trim ring constitute pneumatic bearing, this pneumatic bearing comprises the radially auxiliary hole 26 that is distributed on trim ring middle part, opens at the air-bearing throttle orifice 22 of auxiliary hole end and the annular groove 27 that is connected with described auxiliary hole, this annular groove top is equipped with second valve 28 with 17 sealings of second seal ring at arbitrary auxiliary hole.Base plate 12 is connected with cylinder body 9 by bolt, has added the O RunddichtringO in order to guarantee to be sealed in base plate 12 and the cylinder body 9; Between dividing plate 8 and cylinder body 9, add the O RunddichtringO and guaranteed sealing; Cylinder body 9 tops use bolt to install and fix trim ring 2, add the O RunddichtringO and guarantee sealing between cylinder body 9 and trim ring 2; Piston 1 is placed on trim ring 2 middle part hollow parts; First valve 5 to its inner air feed has been installed on cylinder body 9 tops.

As shown in Figure 3, the schematic representation of trim ring 2 in the pneumatic spring shown in the present.The auxiliary hole 26 that trim ring 2 is radially having some, auxiliary hole 26 ends have air-bearing throttle orifice 22, all auxiliary holes 26 are by axial annular groove 27 UNICOMs, seal ring 17 sealings are used at annular groove 27 tops, choose an auxiliary hole 26 arbitrarily and second valve 28 is installed as air supply opening, provide pressure air by second valve 28 in auxiliary hole 26, all the other auxiliary holes 26 use 16 sealings of first seal ring.

Fig. 4 is the axis side view of piston in the linear anti-deflection double-chamber air-spring provided by the invention.Piston 1 top is provided with the mounting hole 19 of installation load, on the top of piston limiting board 18 is installed, and when pneumatic spring was not worked, piston 1 descended, and limiting board 18 is parked on the surface of trim ring shown in Fig. 22; Piston 1 middle part is an air-bearing working surface 20, air-bearing throttle orifice 22 shown in air-bearing working surface 20 and Fig. 2 cooperates forms complete air-bearing, after pressure air is by air-bearing throttle orifice 22 shown in Fig. 3, form air film between 2 upper inside surface 29 of trim ring shown in air-bearing working surface 20 and Fig. 3, because air film has homogenization, can keep the concentric of piston 1 and trim ring 2 automatically, eliminate the off-centre that piston or load bring, thereby suppressed the beat vibration; In piston 1 bottom is labyrinth seal blade 21, trim ring 2 lower inner surface 25 shown in labyrinth seal blade 21 and Fig. 3 have been formed labyrinth seal, pressure air in pressure air in the air-bearing and the upper chamber 15 is separated in this labyrinth seal, thisly just abandon traditional rubber seal fully, eliminated an important non-linear factor.

Claims (4)

1. linear anti-deflection double-chamber air-spring, contain cylinder body (9), piston (1), be arranged on the cylinder body top and the trim ring (2) that cooperates with piston and be arranged on dividing plate (8) in the cylinder body, this dividing plate is separated into upper chamber (15) and lower chambers (13) with inner chamber of cylinder block, the throttle orifice (14) of some has been arranged at the middle part of described dividing plate (8), it is characterized in that: described lower part of piston is sealed and matched by noncontact seal and trim ring (2); Middle of piston and trim ring constitute pneumatic bearing, this pneumatic bearing comprises the radially auxiliary hole (26) that is distributed on trim ring middle part, opens at the air-bearing throttle orifice (22) of this auxiliary hole end and the annular groove (27) that is connected with described auxiliary hole, second valve (28) is installed with seal ring (17) sealing in this annular groove top on arbitrary auxiliary hole.

2. according to the described linear anti-deflection double-chamber air-spring of claim 1, it is characterized in that: the noncontact seal that described piston bottom cooperates with trim ring is labyrinth seal or magnet fluid sealing.

3. according to claim 1 or 2 described linear anti-deflection double-chamber air-springs, it is characterized in that: be provided with limiting board (18) at the top of piston.

4. according to the described linear anti-deflection double-chamber air-spring of claim 3, it is characterized in that: described piston-shaped for circular or square.

Images