CN102094932B - Adjustable fluid floating raft vibration isolation device - Google Patents

Abstract

The invention discloses an adjustable fluid floating raft vibration isolation device, which is suitable for vibration isolation systems of automobiles, precision machine tools, measuring instruments, ships, submarines, spacecrafts and aircrafts and the like. Fluid (3) is filled in a cylindrical inner cavity of a tubular fluid container (2); a cylindrical floating body (1), of which two sides are provided with vertical oil grooves (6) is arranged in an inner cavity of the tubular fluid container (2), and a spring 4 is arranged between the bottom of the cylindrical floating body (1) and the bottom of the cylindrical inner cavity of the tubular fluid container (2); and the fluid (3) can be lubricating oil. The vibration isolation device has high static stiffness, a good low-frequency vibration isolation effect, a compact structure and light weight; the vibration isolation frequency is adjusted by changing the immersion depth of the floating body on the premise of not changing the stiffness of a vibration isolation system and the actual quality, so that the adjustment of the vibration isolation frequency can be easily realized and the adjustment range of the vibration isolation frequency is large.

Description

Adjustable fluid buoyant raft vibration isolator

Technical field

The present invention relates to be applicable to the fluid buoyant raft vibration isolator of wideband vibration isolation; This vibration isolator can be widely used in the vibrating isolation system of automobile, precision machine tool, surveying instrument, naval vessel, submarine, aerospace craft etc.

Background technique

Fierce day by day along with expanding economy and social competition, people to vibration isolation technique require increasingly high.For example, the latent sound property when the high-comfort requirement of automobile, navigation of submarine, the proper functioning of high-precision surveying instrument etc., all more and more stricter to the requirement of the level of shaking.Traditional vibration isolator only exists

(ω, ω _nBe respectively the natural frequency of energizing frequency and system) vibration isolating effect just arranged.In order to improve the low frequency vibration isolation effect, with regard to the natural frequency of necessary reduction system, this will cause the reduction of system stiffness or the increase of quality.In the design of actual vibration isolator, consider the stability and the weight limits of total system, all be conditional to the minimum rigidity and the biggest quality of system.Therefore, desirable vibration isolator should be to have higher static stiffness and lower vibration transmissibility.

Anti-resonance principle vibration isolator can be realized low frequency vibration isolation not reducing system stiffness and do not increase under the situation of quality, under linear theory, can realize the complete vibration isolation to single-frequency.In practical application, the frequency of excitation force tends to change.Therefore, it is adjustable requiring the isolation frequency of vibration isolator.The adjusting of the vibration isolator of anti-resonance principle at present, isolation frequency mainly realizes through Regulation spring rigidity.Because the restriction of technology, structural design, quiet rigidity requirement etc., the regulation range of spring rate is limited.

Summary of the invention

The technical problem that the present invention will solve is that the deficiency to existing technology exists proposes a kind of adjustable fluid buoyant raft vibration isolator.This vibration isolator has bigger quiet rigidity, good low frequency vibration isolation effect, and compact structure, in light weight; Can under the prerequisite that does not change vibrating isolation system rigidity and actual mass, regulate isolation frequency through changing liquid level height.The adjusting of isolation frequency of the present invention be very easy to realize, and the regulation range of isolation frequency very big (having no restriction on the principle).

Technological scheme of the present invention is; Said adjustable fluid buoyant raft vibration isolator has the tubular fluid container; Its structural feature is; The cylindrical inner chamber of said tubular fluid container is equipped with fluid, and the cylindricality buoyancy aid that both sides are provided with vertical oil groove places said tubular fluid container intracavity, and between the cylindrical inner chamber of cylindricality buoyancy aid bottom and the tubular fluid container bottom spring is housed.

Below the present invention made further specify.

Referring to Fig. 1, the vibration isolation principle of adjustable fluid buoyant raft vibration isolator according to the invention is to utilize the inertial force of fluid to offset the active force of spring, thereby realizes the purpose of vibration isolation.Its technical characterstic has, and controls isolation frequency through regulating liquid level height, can realize the wide range of frequencies vibration isolation; And has a good low frequency vibration isolation effect.

The existing fluid buoyant raft vibration isolator of forming with individual layer fluid container and buoyancy aid (individual layer fluid buoyant raft vibration isolator) is introduced its working principle.Like Fig. 1, when vibration isolator was worked, vibration source (like DENG) was fixedly connected with cylindricality buoyancy aid 1, and cylindricality buoyancy aid 1 is connected with tubular fluid container 2 elasticity, was fixed by vibration isolation object (like pedestal) and tubular fluid container 2.The excitation force that vibration source produces is delivered to earlier on the cylindricality buoyancy aid 1, passes to tubular fluid container 2 by cylindricality buoyancy aid 1 through fluid 3 and spring 4 then, is passed on the protected object body by tubular fluid container 2 again.If act on the dynamic load of tubular fluid container 2 is zero, and then the excitation force of vibration source generation just can not be delivered on the protected object, thereby reaches the purpose of vibration isolation.

Cylindricality buoyancy aid 1 passes to the dynamic load of tubular fluid container 2 and is made up of two-part: the active force of the active force of fluid 3 and spring 4.Fluid 3 acts on the power F on the cylindricality fluid container 2 _fCan be expressed as

$F_f=\mathrm{\&rho;gx}(1+\frac{S}{s^{\&prime;}})S+\mathrm{\&rho;HS}\frac{S}{s^{\&prime;}}\frac{d^{2}x}{{\mathrm{<figure-callout\; id="2"\; label="dt"\; filenames="HDA0000042832390000011.png,HDA0000042832390000012.png"\; state="\{\{state\}\}">dt</figure-callout>}}^2}+f^{\&prime;}---\left(1\right)$

Wherein, X is the axial displacement of cylindricality buoyancy aid 1 relative tubular fluid container 2, and S is the basal area of cylindricality buoyancy aid, and s ' is the cross-section area sum of two oil grooves 6; H is that buoyancy aid immerses the degree of depth in the fluid, the power (generally speaking can ignore) of f ' for considering to be produced behind non-linear and the fluid viscosity.Spring 4 acts on the power F on the cylindricality fluid container 2 _sCan be expressed as

F _s＝Kx (2)

Wherein, K is the stiffness coefficient of spring.

Consider a simple harmonic oscillation, the axial displacement x of cylindricality buoyancy aid 1 relative cylindricality fluid container 2 can be expressed as:

Form.Wherein, A is an amplitude; ω is a vibration frequency, and

is phase place.(3) substitution (1), (2) are got

Offseting when the active force of the active force of fluid 3 and spring 4 (is F _f+ F _s=0) time, vibration isolator has best vibration isolating effect.With (3), (4) substitution (1), f ' is also ignored in (2), and buoyancy aid immerses the depth H in the fluid when obtaining vibration isolator and having best vibration isolating effect _Op:

$H_{\mathrm{op}}=\frac{\mathrm{\&rho;g}(1+\frac{S}{s^{\&prime;}})S+K}{{\mathrm{\&omega;}}^2\mathrm{\&rho;S}\frac{S}{s^{\&prime;}}}---\left(6\right)$

Wherein, ρ is a fluid density, and g is a gravity accleration.

Can know by (6),, can find an immersion depth to make vibration isolator have best vibration isolating effect corresponding to a certain fixing vibration frequency.In theory, under best vibration isolation state, can realize complete vibration isolation (transmissibility of power or displacement is zero).

Can find out by (6) formula, for bigger quiet rigidity value K, only need to guarantee S＞＞s ' just can find the immersion depth of realization easily, reach the purpose that any one vibration frequency is isolated fully.Table 1 has provided S=0.01m ², s '=4 * 10 ^-6m ², ρ=884kg/m ³The pairing best immersion depth value of different quiet stiffness K under the situation.

Table 1, best immersion depth

Can find out by table 1, for the very big situation (K=10 of quiet rigidity value ⁵N/m), in the time of only need the immersion depth value being adjusted to the 0.1m left and right sides, this vibration isolator just can be isolated the low-frequency vibration about 2Hz.And this moment, the controllable size of vibration isolator is built in 125 * 125 * 150mm ³About.If vibration ratio 2Hz is high, the size of vibration isolator also can further reduce.

Structural design by vibration isolator of the present invention can find out that regulating the buoyancy aid immersion depth is to realize very easily.Only need to draw an oil pipe from bottom 5, the control system of additional cover oiling of the other end of oil pipe and oil pumping just can be regulated liquid level height to different vibration frequencies, thereby realized the adjusting to immersion depth.When immersion depth reaches best immersion depth, say separating vibration fully on the principle.

Known that by above the present invention is a kind of adjustable fluid buoyant raft vibration isolator, its advantage has: (1) isolation frequency regulation range is big, and is very easy to realize; (2) quiet rigidity is big, volume is little, in light weight, and have good low frequency vibration isolation effect.

Description of drawings

Fig. 1 is vertical sectional structure schematic representation of an embodiment of the present invention;

Fig. 2 is an A-A sectional structure among Fig. 1.

In the drawings:

1-cylindricality buoyancy aid, 2-tubular fluid container, the 3-fluid,

The 4-spring, 5-bottom, 6-oil groove.

Embodiment

As shown in Figure 1; Adjustable fluid buoyant raft vibration isolator of the present invention has tubular fluid container 2; The cylindrical inner chamber of this tubular fluid container 2 is equipped with fluid 3; The cylindricality buoyancy aid 1 that both sides are provided with vertical oil groove 6 places said tubular fluid container 2 inner chambers, and between the cylindrical inner chamber of cylindricality buoyancy aid 1 bottom and tubular fluid container 2 bottom spring 4 is housed.

Said fluid 3 can adopt lubricant oil.Vibration source is fixed on the cylindricality buoyancy aid 1,2 in tubular fluid container be fixedly connected by the vibration isolation object.On tubular fluid container 2, liquid level detecting instrument is installed.Draw an oil pipe from bottom 5, in the control system of additional cover oiling of the other end of oil pipe and oil pumping.

Oscillating signal to vibration source is analyzed, and obtains its vibration frequency.Vibration frequency according to vibration source calculates best immersion depth by formula (6).Can obtain best liquid level height according to best immersion depth.The liquid level height that the comparison liquid level detecting instrument measures and the difference of best liquid level height, decision oiling or oil pumping.Liquid level height in the final assurance tubular fluid container 2 reaches best liquid level height, thereby realizes reducing significantly the purpose of vibration.

Claims (1)

1. adjustable fluid buoyant raft vibration isolator; Tubular fluid container (2) is arranged; It is characterized in that; The cylindrical inner chamber of this tubular fluid container (2) is equipped with lubricant oil (3), and the cylindricality buoyancy aid (1) that both sides are provided with vertical oil groove (6) places said tubular fluid container (2) cylindrical inner chamber, and between the cylindrical inner chamber of cylindricality buoyancy aid (1) bottom and tubular fluid container (2) bottom spring (4) is housed;

Depth H in the tubular fluid container (2) in the cylindricality buoyancy aid floodlubrication oil _OpCalculated value according to following formula is adjusted:

Wherein, ω is a vibration frequency, and S is the basal area of cylindricality buoyancy aid, and s ' is the cross-section area sum of two oil grooves (6), and K is the stiffness coefficient of spring, and ρ is a lubricant oil density, and g is a gravity accleration.

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