Safety Silencer Air Nozzle

Abstract

An exhaust safety silencer air nozzle includes a housing having an inlet and an outlet with spaced porous baffles. A sound absorbing filter material is disposed in the housing between the baffles so that the air entering the inlet is broken up by the inlet baffle for distribution through the sound absorbing filter material creating a back pressure and exhausts through the outlet baffle at which air flow is further broken up to considerably reduce the noise level and pressure of the exhausted air passing through the silencer. The housing converges at its outlet and terminates in a throated outwardly flared bell to further reduce the exhaust air pressure for cleaning or blowing off a part.

Description

BACKGROUND OF THE INVENTION

The present invention represents an improvement over the gas exhaust silencer disclosed in copending U.S. Pat. application, Ser. No. 81,051 filed Oct. 15, 1970 which was primarily directed to the problem of reducing the noise level of exhausts to an acceptable value.

The present invention is adapted to incorporate that structure and to include therewith additional structure for providing a safety air nozzle which will reduce the pressure of flow of compressed air used for cleaning or blowing off a part to a value well within the limits defined in the Federal Rules. Under the Walsh-Healey Act -- 50-204.8 "compressed air shall not be used for cleaning purposes except where reduced to less than 30 psi and then only with effective chip guarding and personal protective equipment."

It is an object of the present invention to provide an improved safety silencer air nozzle for cleaning purposes constructed to reduce the pressure of air flow from the nozzle below 30 psi.

It is another object to provide within the nozzle assembly a sound absorbing filter material which is soft and compacted to such extent as to develop a back pressure within the housing and accordingly reduce the pressure of air flowing therethrough.

It is another object to provide in conjunction with the housing a converging portion adjacent its outlet end, terminating in an outlet of reduced diameter, and assembled therewith a porous safety bell which merges therewith and flares outwardly with an outlet of increased diameter for again reducing the pressure of air flowing therethrough.

It is another object to construct the safety air bell of a porous material whereby if the outlet is partly abstructed by a person, some of the exhausting air will escape laterally through the walls thereof reducing the pressure of air flowing through the air nozzle, so as to avoid injury.

These and other objects will be seen from the following specification and claims in conjunction with the appended drawing in which:

FIG. 1 is a longitudinal cross section through the present exhaust safety air nozzle.

FIG. 2 is a right end view thereof.

DESCRIPTION OF THE INVENTION

The present safety nozzle 10 comprises a housing which at one end is attached to an exhaust pipe or conduit 12 having connection to a noise producing device such as a die blow off or to an air valve or to a source of compressed air whose pressure normally exceeds 30 psi.

Said housing is generally cylindrical comprising an open ended tubular member 14. One end of member 14 is closed by a front end cap 16 which has a threaded bore 18 or inlet for attachment to compressed air supply pipe 12.

Within member 14 and adjacent end cap 16 is a porous baffle 20 having a radial flange 22 which is clamped between end cap 16 and a radial shoulder 15. Said baffle is formed into a frustoconical section 24, which axially extends through member 14, having an inner closed end 26. Portion 24 forms an expansion chamber 28. Portion 24 is of such length as to provide a sufficiently large internal surface area 30 for impingement of the exhaust or compressed air thereon and has a sufficient chamber area to accommodate free expansion of the compressed air entering chamber 28.

Baffle 20 is made of a gas permeable material which may be heat resistant and have a high porosity such as sintered bronze or the like, to permit the expanded air to enter cylindrical chamber 17 through the porous walls of the cone section 24.

Chamber 17 is filled with a partly compressed sound absorbing filter material 32 of any known composition usually employed in silencer applications of this kind. These may include porous urethane, sponge rubber, felt, steel wool, coil screening and the like. All of these materials have different effects in absorbing sound at various frequencies and for creating a back pressure and, thus, reducing pressure of flow therethrough.

Towards the opposite end of member 14, there is a porous baffle 34 which comprises a perforated disc supported within bore 17 and anchored at 36. Baffle 34 is composed of a gas permeable material having a porosity such as for instance, sintered bronze, or may be merely an apertured disc to permit exit of the muffled air at reduced air pressure from chamber 17 to atmosphere.

In operation, exhaust or compressed air enters the nozzle structure through conduit 12 and into expansion chamber 28. The air is expanded in chamber 28 and impinges radially and axially against the internal surface 30 thereof for penetration through the porous walls of baffle 20 into chamber 17 to penetrate the compressed sound absorbing filter material 32, as indicated by the flow arrows.

Initial sound level of the exhaust air or compressed air is considerably reduced by being minutely broken up as the air penetrates the porous walls of baffle 20. During penetration of the compressed air through the sound absorbing filter material 32, the sound level is further reduced to a still lower value. At the same time, a back pressure is created, further reducing the pressure of the flowing air.

The compressed air then impinges upon baffle plate 34 and passes therethrough. Baffle 34 further breaks up the air flow as it passes therethrough to thereby, still further reduce noise level as the air exits.

Housing 14 outwardly of baffle 34 continues with converging portion 42 defining a conical converging chamber 44. Its outlet 46 is of a reduced diameter compared to the internal diameter of clamber 17. Outlet 46 may be used as a die blow-off without the safety bell 48, on applications of higher air pressure for blowing small parts from dies or tools. At 90 psi, the air is filtered with a noise reduced to 84 DBA at 36 inches.

The safety bell 48 constructed of a porous material is of outwardly diverging shape and at its inner end, is nested and secured within an annular undercut recess 52 in conical portion 42. The internal diameter of the bell at its inner end merges with and forms a continuation of outlet 46 to communicate with the outwardly diverging bore 50 which terminates in the outlet 54 of a diameter in excess of outlet 46.

By this construction, there is a substantial reduction of the pressure of compressed air flowing through the outlet 54 at least below the 30 psi required by the Walsh-Healey Act to provide a safety flow of compressed air for the cleaning or blowing off of a part.

While the baffle 20 is constructed of a porous hard material, the filter 32 is constructed of a softer material and is packed to such extent as to produce a back pressure not allowing excessive air pressure beyond that specified by law to escape through the conical chamber 44, through the bell 48 and outlet 54 for the cleaning or blowing off of a part.

Should the blow off be in operation and placed directly on the skin of the user, under pressure, the safety bell will allow air to be exhausted through its porous surface to atmosphere rather than to break the skin and produce any harmful effects to the worker or other personnel.

Having described my invention, reference should now be had to the following claims.

Claims

I claim:

1. A safety silencer and pressure reducing air nozzle comprising an elongated housing having a chamber;

a sound absorbing partly compacted filter material disposed within said chamber;

one end of said housing being connected to a source of high pressure exhaust air;

a first baffle disposed within said housing adjacent said one end and formed in the shape of a truncated cylindrical cone providing an internal gas expansion chamber, with the apex of the cone remote from and aligned with said inlet;

a second baffle disposed within said housing spaced from the other end thereof;

said first and second baffles being composed of a hard porous permeable material to permit penetration of said high pressure exhaust laterally and longitudinally through the increased internal surfaces of said first baffle into said chamber and through said sound absorbing material for exit through said second baffle to the atmosphere;

said first baffle being adapted to reduce the pressure and noise level of said high pressure exhaust to a first value lower than the initial entering value;

said sound absorbing material being softer than said baffle material and packed to such extent as to produce a back pressure for reducing the pressure of flow through said second baffle to further reduce the pressure and noise level of said high pressure exhaust to a second value lower than said first value;

and said second baffle being adapted to still further reduce the pressure and noise level of said exhaust to a third value lower than said first and second values;

said housing outwardly of said second baffle having a converging portion terminating in an outlet of reduced diameter;

and a safety bell of outwardly diverging shape, at one end secured to said converging portion with its interior surface merging with said outlet and flaring outwardly at its outlet end;

said safety bell being constructed of a porous material throughout whereby with its outlet against a human, air will exhaust laterally outward through its walls further reducing the pressure of outletting exhaust to a safe non-injurious level.