US3357449A - Valve unit for non-lube air compressors - Google Patents

Description

f Dec. 12, 1967 S. F. KING VALVE UNIT FOR NoN-Lum AIR coMPREssoRs 2 Sheets-Sheet l Filed June 24, 1965 @NEX Dec. 12, 1967 s. F. KING VALVE UNIT FOR NON-LUBE AIR COMPRESSORS 2 Sheets-Sheet 2 Filed June 24, 1965 J Q43 A fram/F Y United States Patent O 3,357,449 VALVE UNIT FOR NGN-LUBE AIR COMPRESSORS Smith F. King, Franklin, Pa., assigner to Chicago Pneumatic Tool Company, New York, N.Y., a corporation ot' New .ersey Filed .lune 24, 1965, Ser. No. 466,532 7 Claims. (Cl. 137-5111) This invention relates to ring plate valve units for use in air compressors of the piston type, particularly non-lube air compressors.

The present invention represents an improvement o-ver the valve units disclosed in my Patent 3,177,893, dated Apr. 13, 1965. The subject valve units are of simpler construction and display improved operating characteristics over the valve units of my prior patent. More particularly, the valve units of the present invention utilize disc guides each having a single cylindrical guiding portion which is positionable in a pilot hole arranged in the valve seat. Such an arrangement allows for provision of a iiat surface on the keeper beneath each disc guide, which ilat surface will absorb impact load upon valve opening thus greatly reducing the incidence of disc guide breakage- Long life of the disc guides is achieved by use of a special material which is substantially wear resistant.

The main object of this invention is to provide an improvement in valve units and more particularly in valve guide means for use in valve units of the type used in air compressors.

A more specic object is to provide a valve guide means of simpliiied construction and improved operating characteristics.

Another object is to pro-vide a valve guide means having superior wear characteristics.

The foregoing and other objects and advantages of this invention will appear more fully hereinafter from a consideration of the detailed description which follows, taken together with the accompanying drawings wherein an embodiment of the invention is illustrated. It is to be expressly understood, however, that the drawings are for purposes of illustration and description and they are not to be construed as defining the limits of the invention.

In the accompanying drawings:

FIG. 1 is a cross section of a ring plate valve unit ernbodying the invention and showing the valve unit seated in the intake opening of a non-lube type air compressor of the piston type, only a fragmentary portion of the cornpressor being shown;

FIG. 2 is a section taken on line 2-2 of FIG. l;

FIG. 3 is a section taken o-n line 3 3 of FIG. l;

FIG. 4 is an elevational view of the guide member;

FIG. 5 is a bottom plan view of the guide member; and

FIG. 6 is a fragmentary sectional view of the valve unit, showing the ring plate valves in open condition.

In the drawings is disclosed a valve unit, generally designated 10, embodying the invention. This unit is shown seated in the intake opening 11 of a conventional nonlube type air compressor, generally designated 12. The compressor is of a type having a piston 13 reciprocable in a chamber 14. As the piston moves on its intake stroke in one direction it draws air through the valved intake opening 11 into the piston chamber; and as the piston moves in the opposite direction, it forces the air through a valved discharge opening (not shown). The function of a non-lube type compressor is to supply oil-free compressed air through its discharge end. While the valve unit embodying the present invention may also be used in lube type compressors, it is particularly suited for use in the non-lube type compressor because of the wear resistance of its parts.

The valve unit includes (FIGS. 1, 2, 3) a housing or or body comprising a circular valve seat member 15 and bined thickness of the base 39 of a guide and the thicka complementary mating valve keeper member 16 tightly bolted to the seat member in face to face contact by means of a screw 17. When the valve unit is assembled in the compressor, as in FIG. l, a reduced cylindrical portion 18 of the keeper member Iits into the intake opening 11, and an annular shoulder 19 of the keeper member rests upon a complementary shoulder 21 of the compressor housing. The valve unit is anchored fast in the intake opening 11 by means of a conventional sleeve clamp 22 which sleeves over a reduced cylindrical portion 23 of the seat member and presses tightly -upon an annular shoulder 24 of the latter.

The keeper member 16 further has an inner level face 25 which is held by the screw 17 in contact with an opposed inner level face 26 of the seat member. Formed in the face 25 of the keeper member is an annular shallow airflow channel or recess 27 which communicates by means of a plurality of recessed arcuate ports 28 through the bottom of the keeper with the piston chamber 14 of the air compressor, as in FIG. l. Recessed in the face of the seat member (RIGS. l, 3) is a pair of annular air-flow channels, comprising an inner channel 29 and an outer channel 3i). These channels are concentric to one another and are spaced apart by an annular portion 31 of the face of the seat member. These channels are centered above and are concentrically arranged relative to the air-ilow recess 27 so as to open directly into the latter. The radial extent of the air-flow recess 27 of the keeper member is greater than the combined radial extent of channels 29, 30, and the space 31 between them. A plurality of arcuate ports 32 formed in the body of the seat member communicate channels 29, 31B through the outer face 33 of the seat member whereby intake air entering through a port 34 of the clamping sleeve may iiow through the arcuate ports 32 into the channels 29, 30. Ports 32 are separated from one another by radial rib portions 35 of the body of the seat member.

The area of the inner face of the seat memberv bordering channels 29, 30 defines a seat which is commonv to a pair of radially spaced concentric ring plate or disc valve elements 36, 37. These valve elements are confined between the keeper and seat members for axial movement in the air-ow recess 27. These valve elements are also concentric with channels 29, 30, and the aireflow recess 27. The valves control flow of intake air from channels 29, 30 of the scat memberto the air ow recess 27 of the keeper member. Valve 36 is adapted to seat flat over channel 29; land Valve 37 is adapted to similarly seat over channel 30. These valves are rigid and are formed of hardened stainless steel. The structural nature of the valves avoids not only rusting and distortion thereof, but also avoids consequent undesirable valve seating.

A plurality of spring biased valve guides 38, here three in number and spaced circumferentially degrees apart, yieldably hold the valves in seated condition (FIGS. 1, 2, 4, 5). Each guide comprises a flat surfaced circular base portion 39 from the upper surface of which axially extends a cylindrical lreduced guide stem 41. Each guide is common to both valves. The stem of each guide passes slidably between both valves and extends with a slide lit into a cylindrical bore 42 centered between chan# nels 29, 30 of the seat Imember. The guide stern 41cooperates with the bore 42 in providing a xed path of movement for the guide 38. And the guide in turn guides movement of the valves in a txed axial path.

Both valves lie iiat in a common plane upon the upperN surfaces of the base portions 39 of the guides. Each guide is yieldably biased by a coil spring 43 toward the seat member to hold both valves seated. The air iiow recess 27 has a shallow depth substantially equal to the comis provided in the keeper member at the bottom of the annular recess 27 to receive the base portion of a corre-r sponding guide. Each well is centered in the recess and is coaxial with the corresponding vguide bore 42. The well is slightly greater in diameter than the base of the guide soas to allow rapid escape of air from the well as the guide moves down into it. By means of this arrangement, air d oes not become trapped at the bottoni of the well to check movement of a guide or the valves; and a vacuum is not created in the well below the guide to retard return movement of the valves and guide. The extent to which the valves open is limited by the bottom wall 45 (FIG. 6) of the air ow recess. The valves extend slightly beyond the periphery of the guide base and are adapted to limit upon the bottom wall of the recess 27 as the guide limits at the bottom of its well. So that the valves will not tilt relative to the guides as they move from their seat, a major portion of the radial extent of each valve rests upon the surfaces of the guide bases 39.

The axial depth of each well is preferably not greater than that of the guide base 39 so that when the latter is fully received in the well, the upper surface of the guide base will lie flush with the bottom wall 45 of the air flow recess 27 and the marginal outer portion of the valves will overlie the bottom wall of the air ow recess. The biasing spring 43 is a coil spring which is seated at its bottom end in an annular groove 46 formed in the bottom of the well and is seated at its upper end in an annular groove 47 formed in the underside of the guide base. The grooves are coaxial with the guide. The spring grooves provide a desirable advantage in that they maintain the spring in coaxial relation to the guide and as a consequence prevent the spring from wandering about the well. By means of this arrangement, the biasing force of the spring on the guide is centered on the latter.

In the operation of the device: as the piston 13 moves on an exhaust stroke, a resultant strong suction action is created in the piston chamber; In response to this action, intake air rushing rapidly through channels 29, 30 of the seat member forces the valves to open condition against the resistance of the spring biased guides 38. The incoming air then flows to the air-flow recess 27 and through the ports 28 of the keeper member to the piston charnber 14. Toward the end of the exhaust stroke of the piston, the springs 43 are caused to relax whereupon they act through the guides to return the valves to seated condition. In this opening and closing action the valves and guides do not move relative to one another but move together as a unit. Accordingly, there is no friction action between them. As the valves move away from their seat, they carry the guides with them against the resistance of the springs; as the guides are returned by the spring, they carry the valves with them. The stem portion 41 of the guide moves at all times in its bore 42 as the valves move; it restrains the valves against relative radial movement; and the base portion 39 supports the valves as they move. By means of this arrangement, the valves are guided in their movementy at all times relative to their seat.

During operation of the compressor, the piston 13 cycles at high speed. Accordingly, it is desired `that the valves open and close as nearly -as possible in timed relation to the cycling of the piston to obtain a desirable high efficiency of compressor operation, It has been found that if the biasing springs 43 are too strong, they will cause the valves to close too soon, and if they are too Weak they will undesirably slow closing of the valves. It has been found that desirable results are obtained in the operating efficiency of the compressor when the vbiasing springs 43 are just strong enough to hold the valves closed f upon their seat when the compressor is at rest.

When the valves are opened by the in-rushing air, each guide is forced into contact with the bottom 48 of its well.

So as to provide room for retraction of the spring, groove 46 is of sufficient depth to fully receive the spring when the guide is seated at the bottom of the well, as appears in FIG. 6.

In view of the limited resistance offered by the springs 43, the force with which the valves are opened by the inrushing air causes the guides to impact forcefully against the bottoms of the wells. The bottom 48 of each well is flat and level and cooperates with the corresponding at underside of the guide base to uniformly absorb the impact and thus prevents damage to the guide. As a further protective measure to avoid impact damage to the guide,

the groove 46 at the bottom of the well is deep enough to fully receive the spring asy the guide impacts against the bottom of the well. This enables the base 39 of the guide to impact evenly over the corresponding at bottom of its well and thus spread the reaction of the impacting force evenly over the surface of base 39 of the guide.

Because the valves and valve guides move together as a unit, there is no wearing action of the valves or the guides relative to one another. However, there is a sliding relation yof the stem portion 41 of each guide' relative to the wall of its bore 4Z. To avoid frictional wear here, the wall of the bore has a smooth bearing surface and the guide is substantially friction-free in that it has an inherently greasy or slippery surface. Here, the guide is a one-piece structure. It is preferably formed from material which is light in weight, tough, has an inherently greasy or slippery property, and `which can withstand the high temperatures encountered in compressor applications. A plastic commonly known as Teflon is suitable for this part because it has a low coeicientof friction without lubricant; its mechanical properties are maintained at temperatures of 450500 degrees F.; it is substantially inert to chemical action; and it is light in weight. It is preferred, however, that the Teon be blended with a suitable filler, such as glass, to give it added strength and rigidity.

While an embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes might possibly be made in the design and arrangement of the part without departing from the spirit and scope of the invention. It is intended, therefore, to claim the invention not only as shown and described, but also in all such forms and modifications thereof as may be reasonably construed to fall within the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. In a valve unit for a piston type air compressor, comprising a valve seat member having an inner level face and a pair of concentric air intake channels recessed in said face, a keeper member complementing the seat member having an inner level face and having an annular channel recessed therein in opposed parallel relation to the intake channels, and a pair of concentrically arranged ring plate valves axially movable in the annular channel to open and closed condition over the intake channels,

the improvement comprising: a plurality of wells spaced.

circumferentially equally apart at the bottom of the annular channel of the keeper member and each centered relative to the intake channels, a separate guide bore coaxial with each well formed in the seat member between the intake channels, a valve guide associated with each Well having an annular base portion abutting undersurface portions of both valves, a guide stem portion extending axially from the base portion having slidable movement in the guide bore and extending between the valves and in close relation thereto, a spring seated in each well pressing upwardly against the underside of the base portion of the related guide member so as to yieldably hold the valvesfby means of the base portion seated over the intake channels, the base portion of each guide member being forcefully movable into its corresponding well upon opening of the valves, each well having a at level bottom surface, and the base portion of each guide member having a complementary flat undersurface impactable against the bottom surface of its well upon opening of the valves.

2. The improvement as in claim 1, wherein the diameter of each well is slightly greater than that of the base portion of the related guide member.

3. The improvement as in claim 2, wherein the bottom of the annular channel is llat and level, the valves overhang the base portion of each guide member slightly beyond the radius of the Well, and the axial depth of each well corresponds to the axial thickness of the base portion of the related guide member, whereby the upper faces of the base portions of the guide members are uSh with the bottom of the annular channel when the base portions are fully received in t-he wells and the valves overlie the bottom of the annular channel.

4 The improvement as in claim 1, wherein the springs are substantially identical and the strength of the several springs is just enough to hold the valves seated when the compressor is at rest.

5. The improvement as in claim 1, wherein the axial depth of each well corresponds to that of the base portion of the related guide member, the spring is a coil spring received at its upper end in a shallow annular groove at the underside of the base member and is seated at its opposite end in an annular groove at the bottom of the well, the latter groove being of sufficient depth to fully receive the spring when the base portion of the guide member is fully received in the well.

6. The improvement as in claim 1, wherein the guide member is formed of material having an inherent slippery and greasy surface, and is resistant to high temperature.

7. The improvement as in claim 1, wherein the guide member is formed of glass lled plastic material, the plastic material being of a nature having a property of being slippery and greasy to the touch, and resistant to high temperatures in a range of 450-500 degrees F.

No references cited.

2o WILLIAM F. ODEA, Primary Examiner.

D. I. ZOBKIW, Assistant Examiner.

Claims (1)

1. IN A VALVE UNIT FOR A PISTON TYPE AIR COMPRESSOR, COMPRISING A VALVE SEAT MEMBER HAVING AN INNER LEVEL FACE AND A PAIR OF CONCENTRIC AIR INTAKE CHANNELS RECESSED IN SAID FACE, A KEEPER MEMBER COMPLEMENTING THE SEAT MEMBER HAVING AN INNER LEVEL FACE AND HAVING AN ANNULAR CHANNEL RECESSED THEREIN IN OPPOSED PARALLEL RELATION TO THE INTAKE CHANNELS, AND A PAIR OF CONCENTRICALLY ARRANGED RING PLATE VALVES AXIALLY MOVABLE IN THE ANNULAR CHANNEL TO OPEN AND CLOSED CONDITION OVER THE INTAKE CHANNELS, THE IMPROVEMENT COMPRISING: A PLURALITY OF WELLS SPACED CIRCUMFERENTIALLY EQUALLY APART AT THE BOTTOM OF THE ANNULAR CHANNEL OF THE KEEPER MEMBER AND EACH CENTERED RELATIVE TO THE INTAKE CHANNELS, A SEPARATE GUIDE CENTERED AXIAL WITH EACH WELL FORMED IN THE SEAT MEMBER BETWEEN THE INTAKE CHANNELS, A VALVE GUIDE ASSOCIATED WITH EACH WALL HAVING AN ANNULAR BASE PORTION ABUTTING UNDERSURFACE PORTIONS OF BOTH VALVES, A GUIDE STEM PORTION EXTENDING AXIALLY FROM THE BASE PORTON HAVING SLIDABLE MOVEMENT IN THE GUIDE BORE AND EXTENDING BETWEEN THE VALVES AND IN CLOSE RELATION THERETO, A SPRING SEATED IN EACH WELL PRESSING UPWARDLY AGAINST THE UNDERSIDE OF THE BASE PORTION OF THE RELATED GUIDE MEMBER SO AS TO YIELDABLY HOLD THE VALVES BY MEANS OF THE BASE PORTION SEATED OVER THE INTAKE CHANNELS, THE BASE PORTION OF EACH GAUIDE MEMBER BEING FORCEFULLY MOVABLE INTO ITS CORRESPONDING WELL UPON OPENING OF THE VALVES, EACH WELL HAVING A FLAT LEVEL BOTTOM SURFACE, AND THE BASE PORTION OF EACH GUIDE MEMBER HAVING A COMPLEMENTARY FLAT UNDERSURFACE IMPACTABLE AGAINST THE BOTTOM SURFACE OF ITS WELL UPON OPENING OF THE VALVES.

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