US2249480A - Compressor valve - Google Patents

Description

July 15, 1941.

C. W. LE-E'GARD COMPRESSOR VALVE Filed July 14. I939 Fig.1. 3/

a w m JIIII'VR Ihventor Clifford W Le 9 His Attorney Patenteti Jul y i941 umm STATE 5 sumaziass'o 1 comaass'oa'vstva J Cliil'ord W. Leela-rd, Fort Wayne, Ind, assignor to General Electrlcfiompany, a corporation of New York My invention relates to compressors or the like'and more particularly to valve assemblies for compressors or the like. 7

It is an object of my invention to provide a new and improved valve mechanism for use in.com- Dressers which has a relatively low clearance vol-- ume, minimum pressure losses, low internal stresses in the valve mechanism, quiet opera tion and simplicity of construction.

Further objects and advantages of my inven tion will become apparent as the following description proceeds, and the features of novelty which characterize my inventionwill be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention.

reference may be had to theaccompanying drawing in which Fig. l is an enlarged elevational view, partly-in section, of a compressor embodying the principles of my invention; Fig. 2 is an exploded'view in perspective of the exhaust valve and valve retainer therefor illustrated in Fig. 1,

of a smaller diameter circle mean circumference.

In order to insure maximum efliclency of the having a smaller valve, it is desirable to permit the valve to lift as high as possible without exceeding permissible stress limits. The intake valve is free to bend to the fullest extent because no retainer is provided to restrain or otherwise guide the valve lift but with respect tothe exhaust valve l2,- this aim has been accomplished by shaping the retainer 'to' restrict the lift ofthe ring l6 at the spoke junction to a point'that willgive maximum al-' lowable stress in the spoke. It then becomes desirable to allow the valve to lift above this point intermediate the spoke Junctions because the ring I 8 is now on a smaller diameter. Therefore, 'the retainer 20 is constructed so that the ring ll of the valve l2 intermediate the spoke and Fig. 3 is an enlarged view of a detail of the it valve assembly shown in Fig. 1.

In the drawing, I have illustrated a valve assembly including a valve plate I. having an intake valve 1 I and an exhaust valve l2 secured thereto-to control the passage of working medium through intake passages l3 and exhaust passages M, respectively. The valves H and l2 l5 and a valve portion or ring it supported from the clamping portion l5 by means of a plurality of tapered arms II. In order to limit the lift of the exhaust valve I2 and to absorb the violent opening shock thereof, I have provided a retainer are similar in form and, asbest shown in Fig. 2,

4 each valve comprises a central securing portion an mints in the p k s Junctions can lift a sufllcient amount above the lift at the spoke junctions to compensate for the decreased diameter of the valve I! in the open position. Thus, the degree of valve lift atthe' various points on the ring I6 is limited by the retainer 20 so that substantially constant bending stress is maintained at all points on the ring.

The arm. portion 22 of the retainer. corresponding to the arm or spoke portions I! of the valve 12 are formed so that an even curvature of the valve spokes I! is maintained in order thata constant bending stress may be maintained at be tapered to correspond to spokes'l'l of exhaust or stop member-20 adjacent the exhaust valve l2 and substantially coextensive therewith. The intake valve is not subjected to violent opening shock and, accordinglyyno intake valve stop is required.

In operation, as the rimlia. of valve member it of the valve II or I2 lifts, the diameter of the rim circle decreases because the center portion 15 is clamped to the, valve plate It as by means of a threaded fastening member 2| and castle nut. lie and the spokes ll bend on a ravalve l2, desired.

Describing my invention in greater detail, I

have provided a compressor 23 comprising a cylinder block 24 with a plurality of longitudinal cylinder bores 25 within which pistons l8 are 'arranged for reciprocation in any suitable manner. Inasmuch as the details of the apparatus required to reciprocate the pistons l8 form no part The I arms 22 may of my invention, it is believed to be unnecessary.

to describe the structure used. While -I have illustrated a two-cylinder compressor, it will be understood that as manycylinders and stages of compression as desired may be provided.

dius thereby decreasing the distance of the rim IGa from the vertical center line through the valve. As the lift increases and the diameter of the valve -ring circle decreases, it becomes necessary for the ring ii of the valve l2 to'buckle be- The open ends of the cylinder bores 25 are closed by valve assemblies embodying, the principles of my invention. Each valve assembly includes the valve plate l0 formed from steel, for

example, provided with a plurality of intake passages and a plurality of exhaust passages I 4 I therethrough. While I have illustrated two passages and two exhaust passages ll in eonnection with each cylinder bore 25, it will be understood that any desired number of passages may be employed. Preferably, the intake and exhaust passages l3 and I4, respectively, are dis- A cylinderposed in concentric annular rings. head 25a and the valve plate I! are suitably secured to the compressor casing 24 as by means of threaded screws 26, gaskets 21 being clamped between the valve plate It and cylinder block 24 and also between the valve plate In and the cylin'der head 25a in order to insure fluid-tight joints between the. adjacent'parts of the compressor assembly.

The cylinder head 25a is arranged to provide an intake passage 28 and a discharge manifold 29. The intake passage 28 communicates with an annular passage 30, intake passages l3 being formed in valve plate It to complete the intake path for the working fluid between the intake passage 30 and the cylinder bore 25. The dishead 25a and the block 32.

The intake valve is formed from relatively resilient material, such'as steel, and as previously described, may be provided with a valve portion in the form of an outer ring it maintained in position to cover the intake ports {3 by means of arms or spokes I]v which may be integral with the ring l6. The--ring it of the valve is Just sufficiently wide to cover the valve seats 31 except at the Junction of spokes. order to' allow free passage of-working fluid on both outside and inside of the valve ring l8. The inner ends of the arms or spokes I"! are suitably joined to the clamping portion I! of the valve. While I have illustrated a valve portion in the form of a ring; any suitable shape, such as an arcuate valve portion, supported by spokes or arms may be used. It will be observed that the spokes or arms I! are tapered from the clamping portion l toward the valve portion It so that when the valve opens and causes flexing of the arms l1, theflexing occurs in such a manner that the bending stress is evenly distributed throughout the same in construction as the intake valve so that the maximum opening is at a point on the periphery of the valve ring Isa that is most remotely connected to the center or clamping section IS. The spokes I! are also tapered to 'obtain even stress throughout their length.

In order to limit the opening or the lift of the discharge valve I2, I have provided a valve retainer or stop 20. The discharge valve retainer 20 is substantially the same shape as the discharge valve l2 or co-extensive therewith and is formed so that when supported adjacent to the discharge valve l2 it limits the amount of opening or lift of the discharge valve. The spokes or arms 22 of the retainer 20 are arranged to lie over the valve spokes l1 and formed, preferably. curved, in such a manner that even ourvature of the valve spokes is maintained when the valve lifts. Inasmuch as substantially constant stress is desired at all points on the valve portion, the surface of the retainer is so shaped that in the fully open position of the valve, substantially even stress results. Because the unsupported part of the valve flexes most easily, the greatest lift takes place at that point, between the spokes in the drawing, and considerably more lift can be permitted than at the spoke junctions where the valve is relatively stiil'. Thus, for example, if the upper surface of the retainer is flat, the retainer will be thinnest midway between the spoke Junctions and thickest at the junctions- In order to minimize the noise of the valve l2 or arms I! striking the retainer 20, it is desirable to prevent all parts of the valve l 2 from touching the retainer simultaneously. Therefore,.the rimportion of retainer 20 is suitably modified, as by slightly decreasing the distance between the unstressed valve and the retainer, i.'e., by thickening the retainer, as above formed, in the vicinity of the area midway between spokes in order that the point on the the length of the arms ll. Two or more arms 7 or spokes I! may be used depending upon the degree of opening desired. Thus, the principles.

of my invention are also applicable to a valve having an outer valve portion and an inner clamping portion, the spokes being formed by punching openings in a concentric circle between the valve portion and the clamping portion. It will be observed that spokes or arms I! of the valves act as springs tending to limit the lift of, the valve and also as a closing force when the intake stroke of the piston I8 is completed. When the valve I l opens, the valve portion l6 also flexes between the sections where it is attached to the tapered arms I! thereby giving the maximum lift or opening of the valve at the point on the valve ring 16 which is substantially midway between the arms or spokes valve portion, it, which tends to lift most readily, namely, the area midway between the spokes 22 will strike the retainer first and limit its lift. With this arrangement, the area of contact between valve portion IG and valve retainer 20. will increase progressively in. both directions from the point of initial contact until finally, the valve portion at the junction with the spokes or arms I! will touch the formed surface of retainer 20. Similarly, the area of contact between the arms I] and 22 of the valve l2 and the adjacent surface of the retainer 20, respectively, will increase progressively from the clamping portions outwardly to the valve portion 16 of the valve l2. Thus the retainer finally limits the lift of the valve at all points thereof in such a manner that sudden and uneven stresses are largely obviated.

Securing means have been provided in order to maintain the valves I l and I2 and the retainer 20 in position. -Forthis purpose, I have illustrated the use of a screw 2| having a head portion 38 and a threaded body portion 39 arranged to extend through a suitable opening in the valve plate In and suitable openings in the centrally located clamping portions l5 and 40 of the valves H and I2 and the retainer 20, respectively. The fastening means M is completed by means of a nut 21a and lock washer 4|. I have also illustrated the use of a cotter pin 42 to insure that the nut 2la cannot turn after the assembly has been completed. With this arrangement, it will be seen that the valves II and I2 and retainer 20 are rigidly clamped to the valve plate III" at The discharge valve mechanismissubstanti llv e central or clamping portions e The under side of the head It of the screw 2|, illustrated as facing the intake valve II, is provided 20 presented to the exhaust "valve I2 is prefer-- the samev ably formed in a similar manner for purpose.

In operation, as the piston llstarts its downward stroke, the pressure difference existing between the intake passage 28 and the cylinder bore 25 forces the intake valve ll ofl its seat and the cylinder bore 25 is filled with low pressure working medium, When the piston it reaches the bottom of the stroke, the intake valve H reseats itself and the working medium isthencompressed on the upward stroke of the pistonll. When the working medium in'the cylinder bore 25 reaches a pressure exceeding the pressure in the exhaust manifold 28 and the tension caused by the resiliency of the exhaust valve I}, the exhaust valve l2 lifts on its seat and allows the compressed medium to pass'into the prising a clamping portion, a valve portion and a plurality of arms for supporting said valve portion from said clamping portion, and a retainer member for limiting movement of said valve member in one direction, the surface of said retainer member presented to said valve member being so shaped that the part of saidvalve portion which is vintermediate the junctions of saidvalve portion and said arms contacts said retainer first and the area of contact between said valve portion and said retainer surface increases" progressively from said first point of contact toward said junctions as said valve moves to its open position.

3. In a valve assembly for compressors or the retainer first, the area of contact between said valve-portion and said retainer surface increasing progressively from said first point of contact toward said junctions, and the area of contact exhaust manifold 29. When the piston reaches the top of its stroke, the pressures in the cylinder bore 25 and exhaust manifold is will equalize permitting the exhaust valve it to re-seat and check any flow of high pressure worg medium. back into the cylinder bore I 8. The right-hand cylinder, as viewed'in Fig. 1, is illustrated in the compression stroke while the left-hand cylinder of Fig. 1 is illustrated in the intake stroke.

While I have shown a particular embodiment of my invention, I do not desire my invention to be limited to the particular construction shown and described and I intend in the appended claims to cover all modifications within the spirit and scope of my invention.

What I claim as new and desire to secure by letters Patent of the United States, is: 1. A valve assembly comp a resilient valve member including a claing portion, a valve portion, a plurality of portions for supporting said valve portion from said clamping portion and a retainer member for limiting movement of said valve in one direction, the surface of said retainer member presented to said valve member being so shaped that as the valve moves to its open position one portion of said valve portion remote from the supported portioncontacts said retainer member first and the area of contact between said valve portion and said retainer surface increases progressively from said first point of contact until said valve portion engages substantially all the adjacent surface of I said retainer in order to minimise noise caused by said valve portion striking against said retainer member.

2. In a valve assembly for compressors or the like, a relatively resilient valve member com:

between said arms and said surface increasing progressively from said clamping portion toward said junctions as said valve moves to its open position. 3 I

v4. A valve assembly comprising a relatively resilient valve, said valve comprising a central clamping portion, an outer ring portion, and a plurality of tapered arms extending radially from said clamping portion to said ring portion for supporting said ring portion, a valve retainer supported adjacent said valve, said retainer having substantially the same cross section as said valve whereby corresponding portions of said retainerand said valve are substantially co-extensive, the surfaces of said retainer presented toward said valve being shaped to maintain substantially constant bending stress at all points on said ring portion and an even curvature throughout the extent of said arms as said valve moves to open position.

'5. In a valve 7; biy, a valve formed oi relatively resilient material and comprising a central securing portion, an outer valve portion and a plurality of arms extending from said securing portion to said valve portion, said arms tapering from said central portion to said valve portion, a valve retainer supported adjacent said valve, said retainer having substantially the same cross section as said valve whereby corresponding parts of said retainer and said valve are substantially co-ex'tensive, the surface of said retainer presented toward said valve being shaped to maintain substantiallyconstant bending stress at all points on said valve pc on and an even curvature throughout the t of said arms as said as valve moves to its open position.

w. LlliliiGARD.

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