Filter-silencer For Pneumatic Devices

Abstract

A filter-silencer for pneumatic devices such as air valves, cylinders and the like of the type including a porous filter of a sintered metallic mass wherein, upon clogging of the filter and reduction of the air flow through the exhaust port for the corresponding air device, an auxiliary exhaust path is established which precludes the build-up of excessive back pressures in the pneumatic device and which also provides an audible warning signal indicating the need for servicing of the filter-silencer to restore the porous filter to its normal and intended functional state.

Description

The present invention relates to filter-silencers for pneumatic devices and, in particular, to an auxiliary porting system and warning device in such filter-silencers.

In a typical filter-silencer or muffler, there is provided a pipe nipple or fitting which is attached to the exhaust pipe or port of the associated pneumatic device, be it a valve, cylinder or the like, with the pipe, nipple or fitting carrying a nose-shaped filter head which typically may be a sintered metal mass, as of bronze and of the desired porosity, to provide for the controlled airflow therethrough. The exhaust air from the associated pneumatic device passes through the pipe nipple and is ported to atmosphere through the pores of the sintered mass of the filter. The filter muffles the sound of the exhaust flow, precludes small particles of matter from entering the atmosphere at high speeds and prevents foreign matter from entering the exhaust port of the associated pneumatic device.

Experience with filter-silencers of this type has demonstrated the need for a positive system to deal with the clogging of the sintered filter head, which clogging occurs due to the presence of small particles in the normal air supply for the pneumatic device which tend to clog the pores of the filter-silencer. This reduces the flow of air through the exhaust port and correspondingly may affect the performance of the associated air device since the slowdown or restriction of the exhaust flow usually manifests itself as a functional change in the associated air device.

Broadly, it is an object of the present invention to provide an improved filter-silencer which obviates one or more of the aforesaid difficulties. Specifically, it is within the contemplation of the present invention to provide a filter-silencer wherein, upon clogging of the filter and the establishment of a corresponding predetermined back pressure at the exhaust, an auxiliary port is established to atmosphere to relieve the undesired back pressure and re-establish flow characteristics at the exhaust which are comparable to normal operation wherein the porous filter is substantially unclogged and is functioning in its intended manner.

It is a further object of the present invention to provide an improved filter-silencer wherein in response to the establishment of the auxiliary flow path incident to the clogging of the filter, an audible warning signal is provided indicating that the filter-silencer is operating in its auxiliary mode and that the filter is not functioning in its normal and intended manner.

It is a further object of the present invention to provide a filter-silencer which incorporates both the auxiliary flow capability and warning signal features in a construction which is eminently suited for mass production manufacture at relatively low unit cost and is easily serviced and maintained.

In accordance with an illustrative embodiment demonstrating objects and features of the present invention, there is provided a filter-silencer which comprises an elongated body including a longitudinally-extending passage having an exhaust inlet adapted to be connected to an exhaust flow under pressure and also including an outlet port. A porous filter, typically of a sintered metal mass such as bronze, is connected to the outlet port and is constructed and arranged to pass the exhaust to atmosphere and to preclude foreign matter from entering the outlet port. Means are provided in the elongated body to create at least one auxiliary port which opens to atmosphere. A flapper valve is provided on the body normally blocking the auxiliary port and operable when the back pressure in the passage exceeds a predetermined value as a result of the clogging of the filter for opening the auxiliary port to atmosphere to relieve the back pressure. The flapper valve is constructed and arranged to prevent foreign matter from entering into the body and includes a deformable flapper member of an elastomer seated on the body and selectively operable to open the auxiliary port to atmosphere. Advantageously, the flapper valve vibrates when the auxiliary port is brought into operation such as to emit a high audible pitch warning indicative of the blockage of the main flow and utilization of the auxiliary flow path.

The above brief description, as well as further objects, features and advantages of the present invention will be more fully appreciated by reference to the following detailed description of a presently preferred, but nonetheless illustrative embodiment in accordance with the present invention, wherein:

FIG. 1 is an elevational view of a typical filter-silencer embodying features of the present invention;

FIG. 2 is a sectional view taken substantially along the lines 2--2 of FIG. 1 looking in the direction of the arrows and showing the filter-silencer in its normal mode of operation with the exhaust flow being through the sintered metal porous filter head;

Fig. 3 is a sectional view similar to FIG. 2 but showing the filter head blocked and illustrating the standby mode of operation wherein the air flow is through the auxiliary ports under control of the associated flapper valve; and

FIG. 4 is a sectional view taken substantially along the line 4--4 of FIG. 1 and looking in the direction of the arrows.

Referring now specifically to the drawings, there is shown a filter-silencer embodying the features of the present invention, generally designated by the reference numeral 10. The filter-silencer 10 includes an elongated body 12 in the form of a pipe nipple or fitting which includes a through longitudinally-extending passage 14 providing an exhaust inlet 16 at one end and an outlet port 18 at the other end. Extending inwardly from the end of body 12 having the exhaust inlet 16, there is provided with an externally threaded nipple section 20 providing a convenient means for the attachment of the filter-silencer to the exhaust port pipe or coupling of the associated pneumatic device.

At its opposite end, the elongated body 12 is formed or machined with a reduced diameter mounting flange 22 to which the filter head 24 is appropriately bonded. Filter head 24 is nose-shaped and is fabricated of a sintered metal mass having the requisite porosity and is manufactured in accordance with techniques which are generally understood. Typically, filter head 24 is of a sintered bronze providing a 40 micron filter and is commercially available under the trademark as Model No. . The porous filter head 24 provides an enlarged exhaust chamber 26 contiguous to and in direct communication with the outlet port 18. To facilitate in the attachment of the filter-silencer to the exhaust port to be serviced, the body or nipple 12 is provided with an integral hexagonal nut 28, and once so attached, the filter-silencer 10 passes the exhaust air from the associated pneumatic device to the atomosphere with the appropriate muffling of the sound and prevention of small particles of matter in the exhaust flow from entering at atmosphere at high speed and of foreign matter from entering the exhaust port of the air device. Further description of this generally known type of filter-silencer is deemed unnecessary.

In accordance with the present invention, the filter-silencer 10 is provided with an auxiliary porting and warning device, generally designated by the reference numeral 30, which functions to establish an auxiliary exhaust flow to atmosphere for the filter-silencer 10 upon clogging of the filter head 24 and to provide a corresponding audible warning signal indicating that the principal flow path is clogged and that the filter-silencer 10 is operating in its standby or auxiliary mode. Device 30 includes a plurality of radially extending and circumferentially spaced exhaust ports 32 formed in the elongated body 10. Each of the auxiliary ports 32 communicates at its inner end with the through passage 14 and opens at its outer end through a circumferentially extending medial portion 34 of the body 12. This circumferentially extending medial portion 34 is formed with an annular valve seat 36 which is of a longitudinal extent greater than the corresponding dimension of the auxiliary ports 32. In this illustrative embodiment, seat 36 is of a longitudinal extent in excess of the diamter of the circular exhaust ports 32.

Device 30 further includes valve member 38 mounted on seat 36, which valve member is of the flap action type, is fabricated of elastomeric material (i.e., rubber) and is constructed and arranged to establish an auxiliary flow path at a preset back pressure, but to assure that there will be no flow through the auxiliary ports 32 during normal operation of the filter-silencer and, in the first instance to establish the flap action. Initially, the valve member 38 is sized in relation to the diameter of the supporting seat 36 to be placed in radial expansion when mounted thereon such that the end mounting section 38a is snugly and firmly supported on underlying mounting shoulder 36a of seat 36. The durometer of valve member 38 is selected such that exhaust ports 32 are effectively closed with virtually no leakage for the normal flow characteristics of the filter head 24 and for a limited build-up of back pressures as a result of the closing down or clogging of filter head 24 which is acceptable for the particular design. The durometer of the material employed for valve member 38, the deformation characteristics established by its cross section and related sizing of the exhaust ports 32 is selected such that when the back pressure builds to an unacceptable design value for the particular filter-silencer, the valve member 38 begins to vibrate and opens the auxiliary ports 32 to the atmosphere to establish the auxiliary flow path therethrough as indicated in FIG. 3. During such auxiliary flow, the high speed vibration of the valve member or ring 38 provides an audible high pitch warning signal indicative of the function of the filter-silencer in its auxiliary mode. The showing in FIG. 3 is on an enlarged scale and shows a transitional deformed position for ring 38 in one mode of vibration. Accordingly, it will be appreciated that the flap valve action precludes foreign matter from entering into the filter-silencer 10 through the exhaust ports 32 at which the exhaust flow is radial and outward, as indicated by the representative flow arrows. Desirably, the exhaust ports 32 are dimensioned and the valving action established such that the flow at the exhaust port when operating either in the principal mode (FIG. 2) or in the auxiliary or standby mode (FIG. 3) is substantially the same such that the operating characteristics of the associated air device are not adversely affected by the operation of the filter-silencer in the standby mode since operation in the standby mode may continue for some period of time, depending upon the location of the equipment and the availability of personnel to service the same.

It will be appreciated from the foregoing that there has been provided in accordance with this invention an exceptionally effective filter-silencer which is characterized by its simplicity in construction but is eminently suited to afford its normal function and a standby function accompanied by a warning signal. The device may be manufactured in accordance with well-accepted engineering practices and due to its simplicity in construction, may be made available at relatively low unit cost.

A latitude of modification, change and substitution is intended in the foregoing disclosure, and in some instances some features of the invention will be used without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the spirit and scope of the present invention.

Claims

What I claim is:

1. A filter-silencer comprising a body including a passage having an exhaust inlet adapted to be connected to an exhaust flow under pressure and an outlet port, a porous filter connected to said outlet port and constructed and arranged to pass exhaust to atmosphere and to preclude foreign matter from entering said outlet port, means in said body providing at least one auxiliary port to atmosphere for said exhaust flow and valve means on said body normally closing said auxiliary port and operable when the back pressure therein exceeds a predetermined value as a result of the clogging of said filter for opening said auxiliary port to atmosphere to relieve said back pressure, said valve means being constructed and arranged to normally prevent foreign matter from entering into said body through said auxiliary port during the operation thereof, said valve means also being constructed and arranged to return to its normal position in response to relief of said back pressure to reclose said auxiliary port, said body including at least one radial bore intermediate said exhaust inlet and said outlet port and communicating with said passage to provide said auxiliary port, said body being formed with a circumferentially extending annular seat through which said exhaust port opens to atmosphere and said valve means including a circumferentially extending annular valve member normally disposed in said seat and blocking said auxiliary port, said valve member being fabricated of an elastomeric material and deforming when said back pressure exceeds said predetermined value to periodically open and close said auxiliary port.

2. A filter-silencer according to claim 1 wherein said valve member circumferentially bears on said valve body at one side of said seat, a major portion of said valve member being free of support and confronting said exhaust port and providing a radially deformable flap section which vibrates in response to exhaust flow through said auxiliary port to provide an audible high pitch warning indicating the clogging of said filter.

3. A filter-silencer according to claim 2 wherein said filter is a porous sintered metallic mass and said valve member is rubber.

4. A filter-silencer comprising an elongated body including a longitudinally extending passage having an exhaust inlet adapted to be connected to an exhaust flow under pressure and an outlet port, a porous filter connected to said outlet port and constructed and arranged to pass exhaust to atmosphere and to preclude foreign matter from entering said outlet port, means in said body providing at least one auxiliary port to atmosphere and a flapper valve on said body normally blocking said auxiliary port and operable when the back pressure in said passage exceeds a predetermined value as a result of the clogging of said filter for opening said auxiliary port to atmosphere to relieve said back pressure, said flapper valve being constructed and arranged to normally prevent foreign matter from entering into said body during the operation thereof, said flapper valve also being constructed and arranged to return to its normal position in response to the relief of said back pressure to reclose said auxiliary port and including a deformable flapper member of an elastomer seated on said body and selectively operable to connect said auxiliary port to atmosphere, a plurality of radially extending auxiliary ports formed in said body, each of said auxiliary ports communicating at its inner end with said passage and opening at its outer end through a circumferentially extending portion being formed with an annular valve seat of a longitudinal extend greater than the corresponding dimension of said auxiliary ports and said flapper member being mounted in said seat straddling and normally blocking said auxiliary ports.

5. A filter-silencer according to claim 4 wherein said body includes a circumferentially extending mounting shoulder at one side of and within said seat, an end portion of said flapper member bearing against said mounting shoulder and the major part of said flapper member overlying said auxiliary ports and being free of support and vibrating in response to exhaust flow through said exhaust ports.

6. A filter-silencer according to claim 5 wherein said auxiliary ports are constructed and and arranged to provide a flow characteristic in said passage when in use which is comparable to that for normal operation wherein said porous filter is substantially unclogged.