WO2009084981A1

WO2009084981A1 - Vibration damping device

Info

Publication number: WO2009084981A1
Application number: PCT/RU2008/000718
Authority: WO
Inventors: Ivan Ivanovich Vozhenin
Original assignee: Ivan Ivanovich Vozhenin
Priority date: 2007-12-27
Filing date: 2008-11-24
Publication date: 2009-07-09

Abstract

This technical solution relates to machine-building, more specifically, to vibration damping devices, and can be used in any field of engineering for vibration damping, primarily, in device-making and radioelectronics.

Description

Vibration Damping Device

This technical solution relates to machine-building, more specifically, to vibration damping devices, and can be used in any field of engineering for vibration damping, primarily, in device- making and radioelectronics.

Known (SU Inventor's Certificate 1017852) is an energy absorbing device comprising a case and a cover with an opening through which a rod with a piston passes. On both its butt-ends, the case has grooves symmetrical relative to its center in which pieces of an elastic material with different mechanical compliance are located in an alternating manner. Moreover, corrugated elastic sheets filled with a bulk material are located symmetrically relative to the piston, and the piston rod has springs coaxial with the elastic sheets, wherein one end of each spring is rigidly connected to the piston and the other end is rigidly connected to the case covers. This configuration of the device increases its energy absorption capacity.

Under load, the piston moves down to deform the bulk material, compresses one spring and expands the other spring. Simultaneously, the corrugated sheet is pressed into the grooves on the case that are filled with pieces of an elastic material with different mechanical compliance. This increases the stroke of the piston and provides for a higher energy absorption capacity of the device. Also known (SU Inventor's Certificate 1337580) is a vibration damper comprising a case with cavities in the form of channels symmetrical relative to its axis, tapered towards their ends and arranged at an angle to the case axis, in which balls are located, wherein the ball diameter to channel diameter ratio is selected to be 0.98 ± 0.01.

Vibrations cause reciprocating motion of the balls in the channels. When balls reach the end surfaces of the channels, the vibrations are damped in vibroimpact mode.

Known (SU Inventor's Certificate 1696783) are a method of damping resonance vibrations in the hydromechanical system of elastic damping high-speed rotor supports and a device for its implementation comprising a case with a rotor bearing, an elastic element located between the case and the bearing and a pipeline for supplying working liquid to the case, wherein the entrance opening in the case for the pipeline has a flow section modulator connected to a modulation frequency generator, a vibration amplitude meter and a comparator interconnecting the vibration amplitude meter with the modulation frequency generator. This design increases damping efficiency by extending the frequency range.

The abovementioned technical solutions representing the state of art in the field provide for vibration damping or shock absorption for the device, but most of them have an important disadvantage: their rigidity is a function of the load curve, and therefore in many cases such shock absorbers are insufficient.

The closest counterpart of the device of this invention can be accepted (RU Patent 2124659) a vibration damping device comprising a case, a vibration damping support located inside and a vibration damping element located between the case and the support, wherein said vibration damping element is enclosed in a gas-proof space and comprises a source of saturated steam, a heat accumulator and a liquid / saturated steam system the interface of which is formed on the well- developed surface of the heat accumulator.

Disadvantage of the known technical solution is the high rigidity of the system due to the use of metallic bellows.

The object of this technical solution is to provide a universal device providing vibration damping in the acoustic range and the resultant increase in the vibration protection of the equipment.

It is suggested to achieve said technical result using a vibration damping device comprising a platform installed on at least three dome-shaped elastic gas-proof membrane supports each of which comprises an acoustic pressure adjustment unit located in a gas-proof sound reflecting case, wherein said cased acoustic pressure adjustment unit is in the form of a sound absorbing element comprising a liquid / saturated steam system the interface of which is formed on the well- developed surface of a heat accumulator and an additional ambience isolated chamber having a heat exchanger (heatsink) and allowing making connection to said sound absorbing chamber such that to provide for the transfer of steam from said sound absorbing chamber to said additional chamber and the return of condensed steam to said sound absorbing chamber, further wherein said heat accumulator is an array of alternating heat absorbing elements and spaces between them, the total surface area of said elements (S_∑, m²) is greater than their total volume (V_Σ, dm³) divided by the material heat conductivity (λ m, a W/m^'K), i.e. S_∑ > BV_∑/λ_m (where B is the dimension coefficient equal to 2-10⁵ W/m²K), and the total area of the spaces on a section plane of the heat accumulator that is perpendicular to the acoustic vibration propagation direction is greater than 0.5 dm ; the design efficiency criterion can be accepted as the ratio dP/dV₀ = P/( V₀+ A(CVE)): if A ~2-10⁴ Kdm³, where Vo is the volume of the medium (dm³), P is the pressure in the volume (atm), C is the heat capacity of the heat accumulator (kJ/K^'kg) and E is the specific steam formation heat (kJ.kg), then the total heat capacity of the heat accumulators is at least 3 kJ/°C. The platform can be made from a metal or a metallic alloy, plastic etc.. The membranes can be made from any elastic gas-proof material, e.g. rubber, Mylar etc.. The platform position on the cases of the supports is adjustable with platform position sensors and controlled evaporators located in the sound absorbing chamber and being in the form of enclosed electric heaters.

It is well-known that saturated vapor pressure over liquid only depends on the system temperature. Increasing saturated vapor pressure causes partial transfer of the vapor to the liquid phase and vice versa, i.e. its decreasing causes liquid evaporation, and therefore a liquid / saturated vapor interface having a constant temperature is a perfect absorber of any pressure deviation from the thermodynamically equilibrium one. However, liquid condensation and evaporation are accompanied by heat release or absorption and hence changing the interface temperature. This causes the necessity of controlling the interface temperature using the vapor-liquid phase transition as a pressure variation damper. The more smoothened the temperature variations at the interface the higher the compliance of the device.

The liquid / saturated steam interface is produced on the thermostat surface by wetting due to condensation or adhesion.

As there are currently no sound-transparent films with absolute gas proofing properties for air components, one faces the problem of protecting the gas-proof space from the inlet of foreign gases, primarily, water steam. It is suggested to use an additional gas-proof chamber with diffusion gas pumping from the sound absorbing chamber to the additional chamber, for which purpose the temperature in said additional chamber should be lower than the working liquid evaporation point, and the chamber should be connected to said sound absorbing chamber with two channels: one for pumping vapors from the sound absorbing chamber and the other for the return of the condensed vapors. As the temperature in said additional chamber is lower than that in said main chamber, the partial pressure of the working gas in said additional chamber will also be lower than in said main chamber, and this will cause the accumulation of foreign gases and the condensation and settling of water in said additional chamber.

The basic diagram of the device is shown in the drawing, wherein the following notations are used: platform (1), membrane support (2), case (3), heat accumulator (4), evaporated liquid (5), liquid evaporator (6), additional chamber (7), heat exchanger (heatsink) (8), channel between the vibration damping chamber and the additional chamber (9), channel for the return of condensed liquid from the additional chamber to the main chamber (10) and platform position sensors (11). The device operates as follows.

An acoustic field generated by external vibrations propagates in a saturated steam medium. Having achieved the liquid / saturated steam interface formed on the surface of the heat accumulator due to wetting its surface by the condensate caused by the temperature difference between the steam and the heat accumulator, the acoustic vibrations are absorbed at said interface. The saturated steam passing through the channel (9) to the additional chamber (7) will condensate in said chamber where the heat exchanger (heatsink) can be the wall of the additional chamber (7) cooled by the ambient air from the outside. The condensate cleaned from foreign gases returns through the channel (10) to the sound absorbing chamber. The device of this invention was implemented in an embodiment comprising a platform on three vibration damping supports each of which was a steel case having a volume of 1 dm³ with a 45 mm high heat accumulator in the form of a 1 mm thick coiled aluminum sheet with 0.4 mm spaces between the coils. The total absorption heat capacity of the three heat accumulators was 5 kJ/°C. The supports were gas-proofed with dome- shaped membranes made from metallized LCP films. The working liquid was pentane. The clearance between the support case and the platform was 4 mm and controlled by an IMEl 2-08NNSZW2K sensor. The cases had the evaporated liquid with submerged evaporators on their bottoms. The experimental vibration damping was - 5O dB.

The vibration damping device has no limitations upon dimensions, operation temperature or vibration magnitude, provides for high vibration damping, and its rigidity does not depend on the load curve. Its hardware embodiment is far simpler compared to the known counterparts. Due to these advantages the vibration damping device of this invention will find general use in engineering.

Claims

What is claimed is a

1. A vibration damping device comprising a platform installed on at least three dome-shaped elastic gas-proof membrane supports each of which comprises an acoustic pressure adjustment unit located in a gasproof sound reflecting case, wherein said cased acoustic pressure adjustment unit is in the form of a sound absorbing element comprising a liquid / saturated steam system the interface of which is formed on the well-developed surface of a heat accumulator and an additional ambience isolated chamber having a heat exchanger (heatsink) and allowing making connection to said sound absorbing chamber such that to provide for the transfer of steam from said sound absorbing chamber to said additional chamber and the return of condensed steam to said sound absorbing chamber, further wherein said heat accumulator is an array of alternating heat absorbing elements and spaces between them, the total surface area of said elements (S_∑, m ) is greater than their total volume (V_∑, dm ) divided by the material heat conductivity (λ_m, W/m^'K), i.e. S_Σ > BV_∑/λ_m (where B is the dimension coefficient equal to 2- 10⁵ W/m^2'K), and the total area of the spaces on a section plane of the heat accumulator that is perpendicular to the acoustic vibration propagation direction is greater than 0.5 dm².

2. Device of Claim 1 wherein said device further comprises an evaporator in said sound absorbing chamber.

3. Device of Claim 1 wherein said device allows adjusting the platform position on the cases of the supports with platform position sensors and controlled evaporators located in said sound absorbing chamber.