US2537094A

US2537094A - Air filter for compressed air systems

Info

Publication number: US2537094A
Application number: US746829A
Authority: US
Inventors: Albertus E Schmidlin
Original assignee: Specialties Development Corp
Current assignee: Specialties Development Corp
Priority date: 1947-05-08
Filing date: 1947-05-08
Publication date: 1951-01-09
Anticipated expiration: 1968-01-09

Description

n 19 A. E. SCHMIDLIN 2,531 94 AIR FILTER FOR COMPRESSED AIR SYSTEMS Filed May 8, 1947 2 Sheets-Sheet l mmml IIIIIM IN V EN TOR. Algensl BY ATTORNEY A. E. SCHMIDLIN 2,537,094

AIR FILTER FOR COMPRESSED AIR sYsTEMs :2 Sheets-Sheet 2 Jan. 9, 1951 Filed May 8, 1947 IN V EN TOR.

A/Zenzs iizzz/k agk ATTORNEY Patented Jan. 9, 1951 UNITED STATES TENT OFFICE AIR FILTER FOR COMPRESSED AIR SYSTEMS Application May 8, 1947, Serial No. 746,829

8 Claims.

The present invention relates to compressed air systems, and, more particularly, relates to air filter means for such systems.

The present invention is applicable to com pressed air systems wherein the compressor is driven continually and the compressed air is stored in a receiver but is used only from time to time. In order to maintain the stored air at a predetermined pressure in such a system, bypass means are provided for venting the compressed air supplied by the compressor to the atmosphere when the stored air attains a pre determined pressure value and for again supp ing air to the receiver when the pressure therein falls to a predetermined value.

The present invention is directed to a compressed air system of the foregoing type wherein filter means are provided for filtering the air do livered from the exterior to the intake of the compressor and the by-passed compressed air is supplied to the intake of the compressor when the stored air in the receiver attains a predetermined pressure value.

Accordingly, an object of the present invention is to utilize the by-passed compressed air for cleaning the filter means.

Another object is to provide a blast of air for removing dirt particles from the filter means to reactivate the same.

Another object is to direct lubricating oil carried by the compressed air against the filter means to facilitate cleaning of the filter means.

Another object is to conserve the supply of lubricating oil by recirculating the by-passed air carrying oil picked up during its compression.

A further object is to provide apparatus for accomplishing the foregoing objects and advantages.

Other and further objects of the invention will be obvious upon an understanding of the illustrative embodiment about to be described, or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.

In the drawings:

Figure 1 is a schematic view of a compressed air system embodying the present invention.

Figure 2 is a fragmentary enlarged view of the compressor, partly in section and partly in elevation, illustrating the filter means and the means for reactivating the same.

Figure 3 is a sectional view taken along the line 3-3 on Figure 2.

Figure 4 is an, enlarged longitudinal sectional View illustrating by-pass control means.

Figure 5 is a schematic view of a modified com- 2 pressed air system embodying the present invention.

Figure 6 is an enlarged longitudinal sectional view illustrating modified by-pass control means adapted to be utilized in the system shown in Figure 5.

Referring to Figure 1 of the drawings, there is shown an air compressor It of the multi-stage type herein illustrated as a radial compressor having first, second, third and fourth stages ll, I2, l3 and M, respectively. The outlet of the first stage is connected to the inlet of the second stage by a conduit I5 provided with an intercooler I6 and a valve 21; the outlet of the second stage is connected to the inlet of the third stage by a conduit I! provided with an intercooler iii; the outlet of the third stage is connected to the inlet of the fourth stage by a conduit [9 provided with an intercooler 2i]; and the outlet of the fourth stage is connected to a receiver or reservoir 2| for the compressed air by a conduit 22. The contents of the receiver are adapted to be dispensed through a discharge valve 23 in a conduit 24 connected to the receiver. The arrows applied to the conduits illustrate the direction of the flow of the air therethrough.

Air from the atmosphere is adapted to be supplied to the inlet of the first stage through a filter assembly 25 (Figures 2 and 3) and by-passed compressed air is adapted to be supplied to the inlet by a conduit 26 connecting the interior of the filter assembly to the conduit 15 b means of the valve 21 which is controlled by pressure operable means 28 (Figure 4) connected by a conduit 29 to the conduit 22.

As shown in Figure 4, the valve 27 comprises a body having a chamber therein provided with an inlet 30 and an outlet 3! for connection in the conduit I5, and a by-pass outlet 32 for connection to the conduit 26. A valve seat 33 is formed between the inlet 30 and the outlet 3! and a valve seat at is formed between the inlet 36 and the outlet 32. A valve member 35 for the seat 34 normally is retained thereon by a spring 36 and a valve member 3 for the seat 33 connected for movement with the valve member 35 normally is retained in unseated position and is arranged so that it is seated upon unseating of the valve member 35.

This operation is adapted to be effected by the pressure operable means 28 comprising a body connected to the valve body and having a chamber provided with an inlet 38 to which th conduit 29 is connected, a snap action diaphragm 39 in the chamber responsive to the pressure of the air admitted through the inlet 38, and a stem 36 gonnected to the diaphragm and the valve mem- The filter assembly 25, illustrated more particularly in Figures 2 and 3, comprises a caplike casin 44 mounted over the intake ports 43 in the head 45 of the first stage cylinder, and an absorbent air filter element 46 positioned Within the casing.

The casing 44 comprises a circular top wall 41 provided with a central aperture 49, and a cylindrical depending skirt or side wall 50 provided with a plurality of circumferentially spaced air inlet apertures 51 and having its lower edge turned inwardly and upwardly to form an annular groove 52. The filter element 46 is supported between a pair of disk-like screens 54 each having a top wall 55 adjacent the underside of the top wall 4'! of the casing provided with a central aperture 56 and each having an arcuate downwardly and outwardly extending side wall 51' terminating in a free edge 59 seated in the annular groove 52. The filter element conforms to the shape of screens 54 and has a central aperture 69 in alignment with the aperture 49 of the casing 44 and the apertures 56 of the screens 54.

The filter assembly is removably secured to the cylinder head 45 by a bolt 5|, or the like, extending through the apertures 49, 56 and 6!! and screwed into a threaded aperture 62 of the head.

In order to clean or reactivate the filter element 46, a substantially annular tube 65 is mounted on the cylinder head 45 underneath and adjacent to the arcuate side wall 54 of the inner screen. The tube 65 has a plurality of circumferentially spaced upwardly facing apert res as for direct ng compressed air against the fi ter el ment. The tube is connected in fluid flow communication with the conduit 26 by a depending tube portion 61 thereof which is secured in one end of a passage 69 formed in the cylin r h ad and has the conduit 26 secured in its other end.

In operation, wh le the pressure of the air in the receiver 2| is below a predetermined value, the pressure operable means 28 maintains the

valve members

35 and 31 in seated and unseated po ition, re p cti ely, whereby the air compressed in the first stage I! flows bv wav of the inl t *0, th out et 3! and the conduit IE to the intake of the second tage. Air is admitted to the intake ports 3 of the fir t tage throu h the a.nert"1' s 5! n t e casing 44-. the filter element 46 and its sup ortin screens 54.

Wh n a pr determined pressure has been est bl shed in the recei er, the pressure operable means 28 effects sudden un eatin of the valve m m er 35 and seatin of the va ve member 3?, whereb air com ressed in the first sta e is b pa sed through the valve 21 by way Of the inlet 39 an the out et 32 and is conducted by the conduit 26 to the d trib tin tu e 65 which directs it a ain t the filter element 46.

Th bv-Dassed compr ssed air directed against the filter element is effective to blow out dust, dirt or other foreign particles which have collected on the filter element wherebv the filter element is cleaned to increase the life of its effective use. At the commencement of the unloading phase, the rate of flow of by-passed air exceeds the intake rate of the first sta e due to release of compressed air stored in the intencooer Hi. This effect provides a sudden blast of air wh ch has a highly efficient cleaning action on the filter.

Also, the by-passed compressed air picks up lubricating oil from the first stage of compression and portions of this oil are absorbed by the filter element to further reactivate its dirt catching properties. Since a substantial portion of the by-passed air re-enters the intake ports, the oil carried by this air remains in the system and serves to lubricate the piston and cylinder of the first stage.

When compressed air stored in the receiver is dispensed through the valve 23, the pressure in the receiver drops and pressure operable means 28 is rendered effective to cause sudden seating and unseating of the

valve members

35 and 31, respectively, whereby the compressor supplies compressed air to the receiver.

While the invention has been described in connection with by-passing compressed air from the first stage, it will be understood that compressed air could be bypassed from any of the other stages it so desired.

In Figure 5, a modified compressed air system is illustrated, wherein similar parts have like reference numerals applied thereto. This system illustrates the present invention applied to a single stage compressor Iii having a cylinder 12, the outlet of which is connected to the receiver 2i by a conduit l5. Air from the atmosphere is supplied to the inlet of the cylinder through the filter assembly 25 shown in Figures 2 and 3, and by-passed compressed air is suppl ed to the inlet by a conduit 25' connecting the interior of the filter assembly to the conduit I5. The conduit 26 is provided with a by-pass valve 21 (Figure 6) controlled by pressure operable means 28 connected by a conduit 29 to the conduit l5 The valve 21' comprises a body havin a chamber therein prov ded with an inlet 35' and an outlet 32' for connection in the conduit 26', and a valve seat 34 between the inlet and outlet. A valve member 35 is retained on the valve seat by the pre sure of the air admitted throu h the inlet and the pressure exerted by a spring 36' and is adapted to be un eated bv the stem 46' of the ressure operable means 28 illustrated in Figure 6.

A check valve 15 is provided in the cond it l5 between the points at which the conduit: 26' and 29 are connected thereto for preventing compressed air in the r c iver from flowing back into t compressor outlet or into the by-pass conduit.

The head of the cylinder adjacent its intake ports is provided with a tube 65 (not sho n) for distributing by-pas ed com re sed air and directing the same on the filter elem nt as described in connection with the first embodiment.

In operation. while the pressure of the air in the receiver is below a predetermined value. the pre sure operable means 28 maintains the valve member 35' in seated os tion, w ereby the air compressed in the cylinder 12 flows by way of the conduit 1-5 thro gh the check val e to the receiver. Air is admitt d to the intake of the cyl nder through the filter assembly 25.

When a predetermined pressure has been established in the receiver, the pressure o erable means efiects unseating of the valve member 35, whereby air compressed in the cylinder is bypassed throueh the valve 2'! and is conducted by the conduit 26' to the interior of the filter assembly in the previously described manner.

From the foregoing description, it will be seen that the present invention provides a simple. economical and practical compressed air system wherein by-passed air is used for cleaning or re activating the filter, a sudden blast of air is provided to blow out particles accumulated by the filter, lubricating oil picked up by the compressed air is recirculated in the system to provide lubrication for the cylinder and piston, and a portion of this lubricating oil is utilized advantageously for further cleaning the filter and increasing its dirt catching ability without increasing its resistance to the flow of air therethrough.

As various changes may be made in the form, construction and arrangement of the parts herein, without departing from the spirit and scope of the invention and without sacrificing any of its advantages, it is to be understood that all matter herein is to be interpreted as illustrative and not in any limiting sense.

It is also to be understood that the following claims are intended to cover all the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

I claim:

1. In a compressor having an intake port, the combination of a closure attached to the compressor over the intake port having an aperture for admitting air from the exterior to the intake port, air filter means between said aperture and the intake port, conduit means extending into said closure having an aperture adjacent said filter means for directing compressed air against said filter means at the interior thereof, means for conducting compressed air from the compressor to said conduit means, and means for controlling the supply of compressed air to said last mentioned means.

2. In a compressor having an intake port, the combination of a closure secured to the compressor over the intake port having apertures for admitting air from the exterior to said intake port, air filter means between said apertures and the intake port, means having a plurality of distributing apertures for directing compressed air against said filter means at the interior thereof, means for conducting compressed air from the compressor to said directing means, and means for controlling the supply of compressed air to said last mentioned means.

3. In a compressed air system, the combination of compressor means having means for admitting air from the exterior, air filter means for said admitting means, a receiver, means for conducting compressed air from said compressor means to said receiver, means for directin compressed air against said filter means, a by-pass conduit for conducting compressed air from said conducting means to said directing means, valve means in said by-pass conduit for controlling the fiow of compressed air therethrough, and means onerable in response to the pressure in said receiver for controlling said valve means.

4. In a compressed air ystem, the combination of a compressor having means for admitting air from the exterior, air filter means for said admitting means, a receiver, means for conducting compressed air from said compressor to said receiver having a check valve therein, means for directing compressed air against said filter means, and a by-pass conduitconnected to said conducting means between said valve and said compressor for conducting compressed air from said conducting means to said directing means.

5. In a compressed air system, the combination of a compressor having means for admittin air from the exterior, air filter means for said admitting means, a receiver, means for conducting compressed air from said compressor to said receiver having a check valve therein, means for directing compressed air against said filter means, a by-pass conduit connected to said conducting means between said Valve and said compressor for conducting compressed air from said conducting means to said directing means, valve means in said by-pass conduit for controlling the passage of compressed air therethrough, and means operable in response to the pressure in said receiver for controlling said valve means.

6. In a compressed air system, the combination of a multistage compressor havin means for admitting air from the exterior at the first stage thereof, air filter means for said admitting means, a receiver, means for conducting compressed air from the first stage to a subsequent stage of compression, a conduit for conducting compressed air from the last stage of said compressor to said receiver, means for directing compressed air against said filter means, and a by-pass conduit for conducting compressed air from said conducting means to said directing means.

7. In a compressed air system, the combination of a multistage compressor having means for admitting air from the exterior at the first stage thereof, air filter means for said admitting means, a receiver, means for conducting compressed air from the first stage to a subsequent stage of compression including means for accumulating compressed air, a conduit for conducting compressed air from the last stage of said compressor to said receiver, means for directing compressed air against said filter means, and a by-pass conduit connected to said conducting means between the subsequent stage of compression and said accumulating means for conducting compressed air from said conducting means to said directing means.

8. In a compressed air system, the combination of a multistage compressor having means for admitting air from the exterior at the first stage thereof, air filter means for said admitting means, a receiver, means for conducting compressed air from the first stage to a subsequent stage of compression including means for accumulating compressed air, a conduit for conducting compressed air from the last stage of said compressor to said receiver, means for directing compressed air against said filter means, a by-pass conduit connected to said conducting means between the subsequent stage of compression and said accumulating means for conducting compressed air from said conducting means to said directing means, valve means in said by-pass conduit for controlling the passage of compressed air therethrough, and means operable in response to the pressure in said receiver for controlling said valve means.

ALBERTUS E. SCHNIIDLIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number