GB2223080A

GB2223080A - Pneumatic anti-vibration mounting

Info

Publication number: GB2223080A
Application number: GB8813985A
Authority: GB
Inventors: Gordon Lloyd Pumphrey
Original assignee: IND VIBRATION TECHNOLOGY
Current assignee: IND VIBRATION TECHNOLOGY
Priority date: 1988-06-13
Filing date: 1988-06-13
Publication date: 1990-03-28
Anticipated expiration: 2008-06-13
Also published as: GB8813985D0; GB2223080B; WO1989012764A1; EP0420903A1; AU3776089A

Abstract

A pneumatic anti-vibration mounting with a flat or inverted dish type top cover (2) for mounting equipment below which is an inflatable hollow chamber (1) in the approximate form of a toroid. A central threaded bush (3) attached below the top cover and passing down through the centre of the hollow chamber passed into a cavity in the base (5) which is attached to the bottom of the hollow chamber. Secured to the bottom of the central bush is a sit down bump stop (12). A captive version fo the mounting has an extended base plate (11) with fixing down holes. Inflation of the chamber via a valve (7) or connection in the base or air chamber wall, causes the mounted equipment to rise thereby forming a very efficient vibration and shock isolator.

Description

Pneumatic Anti Vibration Mounting This invention relates to a pneumatic antivibration mounting.

Pneumatic antivibration mountings are not new normally being in the form of convolutted bellows a toroidal ring contained within a metal case, what is known as a rolling diaphrame or a diaphrame fitted into a rigid or semi rigid base.

Versions of the presently available air mounts tend to either have low natural frequency combined with low damping and lack of stability or on the other hand having a higher natural frequeney but providing greater damping and stability while also being captive. The presently described invention combines tL.h the most desirable features of the above described mounting offering a very low natural frequency combined with captivity and a variable degree of damping.

A specfic embodiment of the invention will now be described by way of example with referance tonthe accompanying drawings in which Fig .1. illustrates a plan veiw of a typical mounting Fig .2. illustrates a cut away section along axis A-A1 Indicated in Fig .1. shown with the air chamber inflated with the mounting at its maximum extension.

According to the present invention there is provided a pneumatic antivibration mounting comprising a flexible inflatable hollow chamber, having a hole through ita centre into which is located as a slidding fit. A central threaded bush . The bush top.is attached to the underside of a top cover, onto which the mounted equipment is secured positioned around the central bush immediatley below the centre of the top cover and in contact with the top of the air chamber is positioned a circular distance piece.

Attached to the bottom of the air chamber is a base which has a vertical hole at its top centre, this being of suitable diameter to allow the air chamber not being attached to the threaded bush, when deflected by the supported load, to act in the manner of a rolling diaphragm. An air chamber inflation valve can be positioned so as to connect directly into the air chamber or fitted into the base and connected to the air chamber by a pipe. A captive version of the mounting can be provided by extending the threaded bush down into a taller base with a hollow centre, a suitable base plate being attached to the base, and with addition of a bump stop secured to the bottom of the central threaded bush.

Referring to the drawings a free standing version of the antivibration mounting comprises an inflatable flexible air chamber contained within a protective top cover 2. A central thread bush 3. is a sliding fit into the centre of air chamber 1. and is attached to the underside of protective top cover 2. located around the central bush 3. and positioned between the air chamber 1. and the top cover 2. is a circular distance piece 4. attached to the bottom of the air chamber 1. is a base 5. having a air chamber protective sealing lip 6. which bears as a sliding fit on top cover 2. an inflation valve 7. can be fitted directley into the air chamber through slot 8. or alternativaly an inflation valve 9. can be fitted into the base and connected to the air chamber by a pipe 10.The basenof the free standing version of the mounting does not include items shorn in Fig 1. and Fig 2.

below the line B-31 on Fig 2.

A captive bolt down version of the mounting comprises all the features described above but with an extended base below line 3 - 31 Fig .2. An extended central bush .3. protruding through a hole in the top of base plate 11.

A bump stop 12. when secured to the bottom of the central bush 3. prevents the mounted equipment 13. secured by bolt 14.

from being completely detached from the inter. io which Th ,late 11. is bolted.

The flexible air chamber 3. could be filled or partly filled with liquid, gas , cellular or any suitable resilient material being either inflatable ventedor sealed.

The protective cover 1. is not essential to the satisfactory operation of the mounting normally only being in contact with the bottom of the cover or only the distance piece 4. If desirable the outer periphery of the air chamber 1. can be designed to contact the inside of the downstanding walls of the protective cover 2. while increasing natural frequency slightly, improving damping and mounted equipment stability. For many application a flat plate could be substituted for the protective cover 2.

In operation withcorrect loading the air chamber wili be compressed causing the outer walls to flex and the erea adjacent to the central bush at the bottom to act in the manner of a rolling diaphram the final operating position of the bump stop 17. being appro:: mid way between its fully up and fully down positions, and the mounted equipment being effectively isolate from the base 5. should the air chamber 1. fail or be overloaded the bump stop which is coatted with a flexible material 15.

rests on the supporting member 16. extreme excursions of the mounted equipment laterally are contained by contact between bump stop 12. and base plate 11. also by contact between protetive cover 2. and base plate 5.

Claims

PNEUMATIC ANTI-VIBRATION MOUNTING

CLAIXS 1. A pneumatic anti-vibration mounting comprising a flexible, hollow and inflatable chamber in the approximate form of a toroid. An equipment supporting top cover with a threaded bush attached and passing as a push or sliding fit, down through the inflatable chamber centre hole. A sit down or bump stop is secured to the bottom of the bush. A free standing base is attached to the bottom of the inflatable chamber incorporating an air passage and inflation connection or valve. The bottom of the inflatable chamber has an area surrounding the central bush which is free of contact with the base, thereby allowing it to flex.
2. A pneumeatic anti-vibration mounting as claimed in Claim .1.

wherein a circular distance piece is positioned around the central bush above the inflatable chamberand in contact with the bottom of the top cover.
3. A pneumatic anti-vibration mounting as claimed in Claim .1. or .2. wherein the inflation valve or connection is connected directly into the inflatable chamber wall and not through the base.
4. A pneumatic anti-vibration mounting as claimed in any preceeding Claim wherein the top cover is in the form of an inverted dish with a flat top and a downstanding vertical wall at its periphery, and distanced from the air chamber at all times.
5. A pneumatic anti-vibration mounting as claimed in any preceeding Claim wherein the downstanding periphery walls distance from the top centre are varied to form contact with the inflatable chamber under varying pressures and loads
6. A pneumatic anti-vibration mounting as claimed in Claims 1-3 wherein the top cover is in the form of a flat plate.
7. A pneumatic anti-vibration mounting as claimed in any preceeding Claim wherein a captive version of the mounting is provided by extending the central threaded bush down into a deeper base with a hollow centre. A base plate with securing holes or slots extending up into the base cavity and above, the sit down or bump stop prevents the top cover and therby the mounted equipment from moving more than a predetermined amount.
8. A pneumatic anti-vibration mounting as claimed in any preceeding Claim wherein the hollow chamber if filled or partially filled by with liquid, gas, cellular or any resilient material or any combination of them.
9. A pneumatic anti-vibration mounting as claimed in any preceeding Claim wherein the hollow chamber is sealed.
10. A pneumatic anti-vibration mounting substantially as described herein with reference to figures 1 and 2 of the accompanying drawings.