GB2484769A

GB2484769A - Acoustic mass damper shock absorber with compressible bodies sandwiched between plates

Info

Publication number: GB2484769A
Application number: GB1112261.1A
Authority: GB
Inventors: Paul Ross
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-07-16
Filing date: 2011-07-16
Publication date: 2012-04-25
Anticipated expiration: 2031-07-16
Also published as: GB201112261D0; GB2484769B

Abstract

An acoustic damping / shock absorbing assembly comprising one or more compressible bodies sandwiched between two plates with a plurality of binding means to limit the separation of the plates and pre-compress the bodies, wherein the binding means are flexible or a rigid but floating coupling. The compressible bodies, such as tennis balls, may be hollow, air or fluid filled, spheroidal or domed when pre-compressed and mounted in recesses or apertures symmetrical relative to the centre axis. The assembly may be part of a modular system. The two plates may form upper and lower platforms. The bindings may be symmetrical in the corners for uniform restraint. A set of flexible links may be used or rigid links, mounted with elastomeric washers, not fixed to the plates that float to allow the plates to move together. The bodies may be pre-tensioned but adjustable by tightening or loosening the bindings. The assembly may be used to dampen the impact noise from drum kits or for loudspeakers, audio monitors, washing machines, or used in the heels of training shoes for running to minimise direct noise transmission to floors, shelves, walls and other surfaces.

Description

Acoustic Damping System

Field of the Invention

The present invention concerns improvements in and relating to acoustic damping systems, and primarily platform-type systems, for supporting or abutting high vibration, or high impact noise, equipment such as, for example, loud-speakers, drum kits or washing machines to minimise direct noise transmission to floors, shelves, walls or other surfaces.

Background of the Invention

Acoustic damping platform systems come in a variety of forms, some as simple as cellular resin foam pads that are used as loudspeaker! audio monitor isolation pads.

One simple acoustic damping DIY solution used by some drummers to dampen transfer of impact noise from their drum kit to the underlying floor is a tennis ball impact noise isolating platform that comprises a matrix of tennis balls sandwiched between a pair of sheets of MDF. The tennis balls are each positioned in a respective recess or hole in the opposing boards so as to not roll around and the drum kit is placed on the upper deck of the platform.

Transitory resilient compression of the balls in use soaks up the energy waves from the impacts on the drum kit during drumming. From trials I have found that although this works quite well for drumming impacts, the damping performance is far from optimal and is wholly inadequate for higher frequency impacts and vibrations such as are generated by audio monitors or even by washing machines.

The present invention seeks to provide an improved acoustic damping system suitable for use for supporting, or otherwise substantially abutting, high vibration, or high impact noise, equipment such as, for example, loud-speakers, drum kits or washing machines to minimise direct noise transmission to floors, shelves, walls or other surfaces.

Summary of the Invention

According to a first aspect of the present invention there is provided an acoustic damping or shock absorbing assembly that comprises: a first plate (e.g. upper platform) and a second plate (e.g. lower platform) and at least one resiliently compressible body, the resiliently compressible body being sandwiched between the first and second plates, wherein the plates are bound together by a plurality of binding means that bind the plates tightly together pre-.

compressing the at least one body, the binding means being flexible, or each being a rigid but floating coupling, which operate to limit separation of the plates. Preferably the resiliently compressible body is hollow. Particularly preferably the resiliently compressible body is domed (e.g. substantially hemispheroidal) or substantially spheroidal.

Preferably the assembly has a plurality of such bodies between the plates.

However, in one embodiment the system may be modular with each module comprising a first plate and a second plate and a hollow resiliently compressible domed or substantially spheroidal or substantially hemispheroidal body sandwiched therebetween and the plates bound together.

The plates suitably are rectangular and suitably are symmetrical, e.g. square, but may be of any shape including rounded, e.g. circular or oval. The, or each, body is mounted in a receptacle location, such as a recess or aperture, which is symmetrical relative to the central axis of the assembly. Where there is one body the receptacle location of each plate is at the centre of the plate and where there are several bodies mounted to the plate the receptacles are positioned symmetrically around the centre of the plate. The assembly suitably holds the plates substantially plane parallel to each other, but for some embodiments the plates may be inclined to each other.

The, or each, body may comprise an elastomeric material defining or enclosing a bladder or envelope of air or other fluid, where the body is compressible but the fluid preferably is substantially incompressible. The body may be a whole or half ball form.

The bindings are suitably provided as a set with one proximate each corner of the plates or otherwise configured in a substantially symmetrical arrangement to apply substantially uniform restraint to the system. The bindings may comprise a set of flexible links such as straps that are preferably substantially inelastic. Alternatively the bindings may comprise a set of substantially rigid links, such as, for example, inter-screws or the like to restrain the system together but allow the boards to resiliently move together in use. In the latter case the rigid links are not fixed to the plates and are suitably mounted to the plates via intermediacy of elastomeric washers so that the bindings do not act as a route for transmission of shocks! vibrations from one plate to the other.

Preferably the at least one body is pre-compressed and thereby pre-tensioned to a predetermined level of resilient return force by the bindings. We have found that the use of the bindings to hold the body pre-compressed greatly enhances the performance of the system for acoustic damping.

Brief Description of the Drawings

A preferred embodiment of the invention will now be more particularly described, solely by way of example, with reference to the accompanying drawings in which: Figure 1 is an exploded assembly perspective view of a first embodiment of the shock absorbing! acousUc dampening system having a pair of square plates to sandwich four resihent bodies and a flexible binding at each corner of the plates; Figure 2 is an end elevation view of a single ball module of a modular shock absorbing! acoustic dampening system of a second preferred embodiment, here again with a flexible binding at each corner of the plates; Figure 3 is an end elevation view of a variant of the single ball module, here with a rigid inter-screw as the respective binding at each corner of the plates.

Figure 4 is a side elevation view of a sports shoe incorporating a shock absorbing system of the present invention; and Figure 5 is a plan view of a sports shoe with upper removed to more clearly show the shock absorbing unit.

Descriotion of the Preferred Embodiment Referring firstly to Figure 1, the first preferred embodiment of the shock absorbing! acoustic dampening system comprises a pair of square plates I a, I b to sandwich four resiliently compressible bodies 2a-d in a symmetrical arrangement. The plates Ia, lb may be of metal or be wooden boards or of plastics or any other suitable material or combination of materials and suitably are substantially fiat / planar but need not necessarily be so. Suitably they are substantially rigid.

The plates Ia, lb are here held substantially plane parallel and a maximum distance apart by a set of four inelastic flexible binding bands/ straps 3a-d each of which is fitted at a respective comer of each plate I a, I b to ensure that the four resilient bodies 2a-d are pre-compressed to a set extent.

Each of the resiliently compressible bodies 2a-d has the form of a hollow spherical ball made of an elastomeric material (e.g. natural rubber) and that holds a volume of air therewithin in the manner of a bladder. The resiliently compressible bodies 2a-d are held in their respective positions in the square plates I a, I b by aligned through-holes (or recesses) 4a-d in each of the plates Ia, lb and the external face of each plate Ia, lb is capped off by a fascia/ cover sheet I a', I b'. Each of the flexible binding bands 3a-d ties at one end to a first of the plates I a by passing through an eye 5a-d adjacent a respective corner of the plate I a. Each band 3a-d ties at its other end to the second of the plates I b by passing through an eye 5a-d adjacent a respective corner of that second plate I b The bands 3a-d serve as flexible connectors that are taut when under load, but collapse when impact is applied to the first plate I a of the assembly to allow the assembly to cushion the loading.

The bands 3a-d are suitably adjustable such as by use of a clasp or buckle so that the separation of the plates I a, I b from each other may be adjusted to give a desired level of pre-tensioning of the resiliently compressible bodies 2a-d for the selected use. By selection of a suitable pre-tensioning level the performance of the assembly for attenuating vibration transfer can be substantially optimised.

In the embodiment of Figure 2 the assembly has only one resiliently compressible body 2 and this is positioned at its centre held by two aligned central opposing through holes 4 of the first I a and second plate I b. This simple unit suits use in modular constructions whereby this unit is flanked by other such units to create a matrix of units sufficient to cover a desired area.

Modular units may be spaced a substantial distance apart from each other to cover a large area with relatively few units or close together to form a substantially contiguous platform or wall. They may have means to inter-lock together alongside each other or even be made to attach to devices as desired -e.g. to the base of a speaker or washing machine or to a sidewall of the device that abuts another surface. The units may even be built into a device.

In the variant of the second embodiment shown in Figure 3 the assembly is held together by rigid links! rigid floating connectors, here inter-screws 6a-d, rather than flexible straps! bands. These inter-screws 6a-d are nut-and-bolt like devices such as are used to hold together boards or carcase units. The heads at each end of the inter-screw 6a-d are counter-sunk, ie seat into a respective recess in the plate I a, I b. Here they rest on rubber washers 7 and they are not affixed to either plat& platform I a, I b. The depth of the recess for the heads at each end of the inter-screw 6a-d is such that full compression of the unit will not lead to the inter-screw 6a-d being impacted. These inter-screws 6a-d or other rigid links! rigid floating connectors are substantially isolated from the impacts and from contact with the plates I a, lb. When any vibration or impact is applied to the first plate (top platform) Ia, the inter-screw! connector 6a-d does not transfer this to the second plate (bottom platform) I b. Screw threaded adjustment of each inter-screw! connector 6a-d may be used to set the required level of pre-compression/ pre4ension of the assembly.

The end uses! apphcations for the units are many and diverse. For example they may be butted to or attached to or built into ilooring panS or even flooring joists, beams or other structural flooring supports or wafl structures. They might be recessed into or built into a structural flooring support, such as a split flooring joist or a joist hanger for suspending joists from wafls! masonry, for example, and most notaby when rigid interconnectors 6ad are used as the bindings. They may be used in other devices and shock-absorbing surfaces! interfaces too, such as in a bicycle seat or other seat or in the heel and! or soe of footwear such as, for example, a sports shoe.

Turning to Figures 4 and 5, these show the use of the shock absorbing! acoustic dampening system in the construction of the heel of a sports shoe.

Here the unit is buHt into the shoe's heel to act as cushion against impact to the user's he& when jumping, jogging or running. The upper and lower platforms! plates Ia, lb bound together by rigid inter-connectors 6a, 6b sandwiching the resiliently compressible body 2 are not plane paraUel to each other but rather are indined to each other to better conform ergonomicaHy to a user's foot. This may be an adjustable inclination, where the bindings! inter-connectors 6a, 6b are adjusted up or down to differing extents (e.g. by the wearer) to enab'e shaping to fit the foot and e.g. addressing pronation of the foot arch) while maintaining the required pre-compression and cushioning level. A unit may also be integrated into the middle of the soe and most notably so where the soles are of the type that use cellular air pockets in their design.

Although the assembly of the present invention is shown as comprising a single shock absorbing tier, it could be multi-tiered for extra shock absorption capacity, ie have a first tier with at least one resilienUy compressibe body 2 and above that at least a second tier having at least one resiliently compressible body 2.

In each embodiment the first and second plates la, lb provide structure to the device and the assembly performs as a spring and damper mechanism. The resiliently compressible bodies 2, 2a-d act as loaded springs and are compressed between the platforms Ia, lb, held in place by the facing holes or recesses 4a-d in the plates/boards la, lb. The diameter of the holes or recesses 4a-d is such that the crest of the resUienfly compressible bodies 2, 2a-d protrudes thereinto and a wider diameter of each resflienfly compressible body 2, 2a-d is flattened against the insides of the structure to create a lateral platform of air, which adds stability to the device. The binding straps 3a-d (or other retainers 6a-d) attach to the first and second plates la, lb and hold the device together under load, preventing the compression of the resilienfly compressible bodies 2, 2ad from separating the first and second plates la, lb and also act as dampers to prevent motion of the boards in lateral or rotational planes. The device can be described in terms of a mass and damper model.

Wave energy transmitted from the first plate la to each resWentiy compressible body 2, 2a-d causes the body to deform. The body will then push back on the plate Ia at the frequency of the inital wave. However the first plate Ia is constrained by the bindings 3a-d, 6a-d (under load acting as dampers) and therefore cannot return past its starting point i.e. to oscillate at the frequency of the original energy wave. The wave is therefore damped and energy is dissipated primarily through friction on the system as heat in the body 2, 2a-d and bindings 3a-d, 6a-d, though the energy absorbed is not generally enough to show any appreciable change in temperature of the system.

The device is tunable by varying the elastic properties of the body 2a-d, tension of the bindings 3a-d, 6a-d and optionally also the choice of platform Ia, lb material. This could include composite sheet materiais that have a foam (or similar) layer, which would help damp vibrations before they get to the bodies 2, 2a-d. It may also help the device cope with a wider frequency range

Claims

SClaims 1. An acoustic damping or shock absorbing assembly that comprises: a first plate and a second plate and at least one resiliently compressible body, the resiliently compressible body being sandwiched between the first and second plates, wherein the plates are bound together by a plurality of binding means that bind the plates tightly together pre-compressing the at least one body, the binding means being flexible, or each being a rigid but floating coupling, which operate to limit separation of the plates.
2. An acoustic damping or shock absorbing assembly as claimed in claim 1, wherein the resiliently compressible body is hollow
3. An acoustic damping or shock absorbing assembly as claimed in claim 1 or claim 2, wherein the resiliently compressible body is domed or substantially spheroidal
4. An acoustic damping or shock absorbing assembly as claimed in any preceding claim that serves as a module of a modular system and comprises a single resiliently compressible body sandwiched between first and second plates.
5. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the first and second plates are upper and lower platforms.
6. An acoustic damping or shock absorbing assembiy as claimed in any preceding claim, wherein the, or each, body is mounted in a receptacle location, such as a recess or aperture, which is symmetrical relative to the central axis of the assembly.
7. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the, or each, body comprises an envelope or bladder of trapped air or other fluid.
8. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the bindings are provided as a set with one proximate each corner of the plates or otherwise configured in a substantially symmetrical arrangement to apply substantially uniform restraint to the system.
9. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the bindings comprise a set of flexible links.
10. An acoustic damping or shock absorbing assembly as claimed in any of claims 1 to 8, wherein the bindings comprise a set of substantially rigid links not fixed to the plates that float to allow the plates to resiliently move together in use.
11. An acoustic damping or shock absorbing assembly as claimed in claim 10, wherein the rigid links are mounted to the plates via intermediacy of elastomeric washers or other elastomeric mounting interface.
12. An acoustic damping or shock absorbing assembly as claimed in claim 11, wherein the rigid links are mounted to the plates counter-sunk in recesses so as to not protrude when the resiliently compressible body is further compressed in use.
13. An acoustic damping or shock absorbing assembly as ciaimed in any preceding claim, wherein the at least one body is pre-compressed and thereby pre-tensioned to a predetermined level of resilient return force by the bindings.
14. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the extent to which the at least one body is pre-compressed may be adjusted by tightening or loosening the bindings.
15. An acoustic damping or shock absorbing assembly as hereinbefore described with reference to the accompanying drawings.Amendment to the claims have been filed as follows Cbms (4 1. An acoustic damping or shock absorbing assembly that comprises: a first plate and a second plate and at least one resiliently compressible body, the resiliently cD compressible body being sandwiched between the first and second plates, wherein Ft, the plates are bound together by a plurality of rigid binding means that bind the c'bJ plates tightly together pre-compressing the at least one body, the binding means being a rigid couphng, which operates to limit separation of the plates.2. An acoustic damping or shock absorbing assembly as claimed in claim 1, wherein the resiliently compressible body is hollow 3. An acoustic damping or shock absorbing assembly as claimed in claim I or claim 2, wherein the resiliently compressible body is domed or substantially spheroidal 4. An acoustic damping or shock absorbing assembly as claimed in any preceding claim that serves as a module of a modular system and comprises a single resiliently compressible body sandwiched between first and second plates.5. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the first and second plates are upper and lower platforms.6. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the, or each, body is mounted in a receptacle ocation, such as a recess or aperture, which is symmetrical relative to the central axis of the assembly.7. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the, or each, body comprises an envelope or bladder of trapped air or other fluid.8. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the bindings are configured in a substantially symmetrical arrangement to apply substantially uniform restraint to the assembly Ft, 9. An acoustic damping or shock absorbing assembly as claimed in any of claims 1 to 8, wherein the bindings comprise a set of rigid links that are fixed to either or both plates, and aUow the plates to resiliently move together in use, and engage to limit separation of the plates.10. An acoustic damping or shock absorbing assembly as claimed in any of claims 1 to 8, wherein the bindings comprise a set of rigid links crafted as elements of the plates that allow the plates to resiliently move together in use, and engage to limit separation of the plates.11. An acoustic damping or shock absorbing assembly as claimed in claims 9 & 10, wherein the rigid inks are mounted to the plates via intermediacy of elastomeric washers or other elastomeric mounting interface.12. An acoustic damping or shock absorbing assembly as claimed in claim 9 & 107 wherein the rigid links are mounted to the plates counter-sunk in recesses so as to not protrude when the resiliently compressible body is further compressed in use.13. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the at least one body is pre-compressed and thereby pre-tensioned to a predetermined level of resilient return force by the bindings.14. An acoustic damping or shock absorbing assembly as claimed in any preceding claim, wherein the extent to which the at least one body is pre-compressed may be adjusted by tightening or loosening the bindings. (SI15. An acoustic damping or shock absorbing assembly as hereinbefore described with I,,, reference to the accompanying drawings. (SI