US3540470A - Diaphragm valve for compressors - Google Patents

Description

[72] inventors Charles Schmid Milwaukee, and Whitney 1. Grant, Muskego, Wisconsin [2]] Appl. No. 737,704 [22] Filed June 17, 1968 [4S] Patented Nov. 17, 1970 [73] Assignee Vilter Manufacturing Corporation Milwaukee, Wisconsin a corporation of Wisconsin [54] DIAPHRAGM VALVE FOR COMPRESSORS 4 Claims, 9 Drawing Figs.

[52] U.S. Cl 137/5l6.17 [51] Fl6k 15/14 [50] Field ofSearch ..l37/516.15,

516.17. 516.19. 516.21, 512. 15; 29/557, (Shot Digest) [56] References Cited UNITED STATES PATENTS 1,222,321 4/1917 Peters l37/516.15

D United States Patent Shot Peening Process, now part of regular production operations in many industries, by Rick Mansell, the Modem Industrial Press, May 1949, pp. 46, 48, 50 and 52.

Primary ExaminerWi1liam F. ODea Assistant Examiner-William H. Wright A ttorney- Lieber and N illes ABSTRACT: A diaphragm type discharge valve for a reciprocating gas compressor which is prestressed to a dish shape or concave formation by a stamp and die operation and which is specially treated as by a shot-peening operation to relieve internal stresses.

Patehted Nov. 17,, 1970 Sheet Milli/As 3 fill/I111;

Patented Nov. 17, 1970 Sheet DIAPHRAGM VALVE FOR COMPRESSORS BACKGROUND It is common practice in the refrigeration field to employ gas compressors of the-reciprocating piston type having one or more compression stages for acting upon the gaseous refrigerant utilized in the system. Each such compression stage comprises a cylinder having an annular gas inlet chamber extending outwardly about the end thereof and housing an annular spring loaded suction valve past which gas is admitted upon the suction stroke of a piston slidably confined in the cylinder. The cylinder is provided with an end closure cap or head coacting with the cylinder bore to provide an annular displacement chamber communicablewith the gas inlet chamber for receiving the gas admitted past the valve, and means is provided for reciprocating the piston within the cylinder toalternately draw the gas into the displacement chamber and discharge the same from the chamber under high pressure.

For permitting discharge of high pressure gas acted upon by the piston, it is customary to provide the end head of the cylinder with an annular series of high pressure discharge ports communicable with the displacementchamber and past suitable valve means and with a compression chamber from which high-pressure gas is distributed to the system. While the discharge valve may vary in design, it has heretofore been common practice to utilize a disc-shaped diaphragm type valve secured to the end head at its medial portion with the portion adjacent its outer periphery overlying the discharge ports, suitable means being provided for maintaining the diaphragm valve seated under predetermined load so that proper compression of the gas is obtained.

" Normally, these diaphragm valve plates are formed ofa special grade of flat spring steel strip material available only at a premium price. Since these valves are subject to violent impact and to frequent high speed flexing, the material from which the diaphragms are formed must be ofa specified hardness and chemical analysis as well as free from internal stresses, cracks and other defects. Also, when formed of flat stock, the diaphragms, when relaxed, must be perfectly flat and surface finished so as to be free of any surface defects whatsoever to insure proper seating, and while efforts have I been made in the past to eliminate the problems attendant accurate seating by dishing the valve disc or diaphragm plate, it has been found that internal stresses are developed in the forming or shaping of these diaphragms which objectionably weaken the same.

SUMMARY The present invention obviates the problems and objections attendant these prior efforts to provide a diaphragm valve for gas compressors which is adapted to effectively and properly seat while permitting formation of the same from relatively inexpensive'and readily available coiled stock.

In accordance with the present invention, the compressor discharge valve diaphragms may be stamped and/or punched from coiled sheet material with the individual diaphragm discs being formed concave or of dish-shape with the aid of suitable dies under pressure as by means of a press, the dish-shaped diaphragms being thereafter treated by a shot peening operation under controlled conditions to thereby relieve the internal stresses developed as a result of the forming operation.

These and other objects and advantages of the invention will become apparent from the following detailed description.

THE DRAWINGS A clear conception of the features constituting the present improvement and of the method of constructing diaphragm valves in accordance with the invention and the mode of applying and utilizing the same in a typical reciprocating gas FIG. 1 v is a, fragmentary vertical section through the cylinder, discharge valve assemblage, piston and frame of a typical gaseous refrigerant compressor embodying the invention, the valve diaphragm being shown in seated condition;

FIG. 2 is a somewhat enlarged fragmentary section through the discharge valve assemblage but showing the diaphragm unseated;

FIG. 3 is a diagrammatic view schematically illustrating the initial step of stamping and forming the diaphragm'fr'om'a' coil or roll of sheet material;

FIG. 4 is a plan view of one of the diaphragms as initially punched,-stamped or otherwise formed to a dish-shaped fr o a sheet of suitable material;

FIG. 5 is a section through the diaphragm taken along the line 55 of FIG. 4; i

' FIG. 6 is a perspective view of one of the dish-shaped, diaphragms held in position within a suitable rotatable fixture DETAILED DESCRIPTION While the invention has been shown and described herein as being especially advantageously applicable to reciprocable piston compressors for refrigerant gases, it is not intended to unnecessarily restrict the improvement to such usage, and its also contemplated that specific descriptive terms employed herein shall be given the broadest possible interpretation consistent with the disclosure.

Referring particularly to FIGS. 1 and 2 of the drawings the portion of a typical compressor embodying the invention as shown therein comprises, in general, a cylinder I0 having a bore 12 and an end closure head 14 cooperating with the cylinder to form a displacement chamber within which 'a piston 16 is slidably confined. Surrounding the peripheral portion of the cylinder 10 adjacent the end head 14 is an annular gap or space 18 communicating with a series of inlet ports 20 and with the-interior of the cylinder 10 past an annular valve 22, the valve 22 being constantly urged to seated position closing the ports 20 as by means of springs 24. The piston l6 is adapted to be reciprocated within the bore 12 by means of a connecting rod 26 operated by the usual crank or eccentric, not shown.

The suction ports or passageways 20 communicate with a gas supply chamber 28, and as the piston 16 is moved away from the end head 14, the annular spring loaded suction valve 22 is caused to unseat against the action of the springs 24 and gas is drawn from the chamber 28 through the ports 20 past the valve 22 through the annular space 18 and into the upper portion of the displacement chamber. The space 28 is formed within a frame 30 which also mounts the cylinder 10 and its associated parts.

The end head 14 is, in turn, provided with an annular series of spaced outlet or discharge ports 34 communicable with the displacement chamber and with a compression chamber 36 formed in the cap 38, flow of gas through the ports 34 being under the control of a discharge valve 40. As shown, the high pressure discharge valve 40 constructed in accordance with the present invention comprises a dish-shaped disc or diaphragm which is mounted at its medial portion on the end head 14 as by means of a bolt or machine screw 42 .withits outer peripheral portion overlying the ports 34. In actual practice, it is preferable to form the end head or plate 14 with an annular upwardly open channel 44 or the like interconnecting the ports 34, the edges of which provide a seat for the valve diaphragm 40. It is also customary to provide means for limiting movement or flexing of the diaphragm valve 40, and this may be accomplished through use of a spacer 46 and one or more backup plates 48 also mounted on the retaining screw or bolt 42. As shown, these backup plates or discs 48 are also dish-shaped 'an function to restrict outward movement of the peripheral portion of the valve 40. The diaphragm valve 40, spacer 46 and backup plates 48 are retained in assembled condition on the end head 14 by means of a washer 50 and nut 52 also carried by the bolt 42, and the end head and valve assemblage is normally retained in position within the chamber 36 formed in the cap 38 as by means of a relatively heavy coil spring 54. Thus, during the outward compression stroke of the piston 16 the gas from within the displacement chamber of the cylinder forces the diaphragm 40 from its seat and allows thecornpressed gas to enter the chamber 36 from which the compressed gas is distributed to the system.

In accordance with the present invention, the individual diaphragm valves 40 are initially formed to the shape shown in FIGS. 4 and 5 as by stamping the same from a coil or roll 60 of suitable sheet material, as shown in FIG. 3, by means of suitable punches and' dies 62. The individual diaphragms thus formed have internal stresses which are objectionable and must be relieved, such internal stresses having resulted from the stamping and forming operation. Accordingly, to relieve these internal stresses in the dish-shaped diaphragms, each diaphragm 40 is placed in a suitable jig or fixture 66 as shown in FIGS. 6 and 7. This fixture 66 may comprise a table or sup port member 68 having a plurality of annularly spaced clamps 70 cooperable with the periphery of the diaphragm 40 to hold the same securely in position. The support 68 is preferably rotatably carried on a vertical shaft 72, and suitable means such as a manually manipulable crank 74 may be employed to move the clamps to and from effective clamping position. As the shaft 72 and support 68 is rotated by any suitable means, the exposed surface ofthe diaphragm 40 is subjected to a blast or spray of shot 76 from the nozzle 78 of a shot peening device. After one surface of the diaphragm 40 has been thus treated it is reversed in the fixture 66 as shown in FIG. 7 and the other surface is subjected to the same type of shot peening operation.

in the shaping operation performed with the aid of punches and dies as shown in FIG. 3, the amount of dishing or curvature of the diaphragm should be controlled in the dies so as to provide sufficient bow or curvature to insure return and prevent the diaphragm plate from snapping into the opposite direction in operation. This, to some degree, is dependent upon the type of material used and the thickness thereof. With regard to the shot peening operation, the size of the shot utilized and blown against the surface of the diaphragm plate and the intensity at which its is blown should be such as to provide for the relief of internal stresses without overstressing and damaging the material, and this operation as shown in H68. 6 and 7 should be performed after the plates are punched and dished.

The finally shaped and treated diaphragm is then applied as shown in FIG. 8 wherein one of the plates 40 is shown as being applied through a center hole to the bolt 42 with the concave face bowed over the annular seat formed by the channel 44 communicating with the ports 34, the parts being shown in their released state before bolting in this figure. Accordingly,

upon application and tightening of the nut 52 as in FIG. 9, the

tendency to return to closed position quickly upon relief of the gas pressures within the ports 34 and annulus 44, thus resultmg m a more rapid and efficient operating part.-lt should also be noted that the shot peening of the edges on the holes in the diaphragm 40 is important inasmuch as this is where cracks and failures normally begin, and by utilizing a fixture such as shown and described herein for the shot peening operation, all of the edges are effectively treated and completely covered on both sides of the diaphragm plate. The dish-shaped backup plates 48 may, of course, comprise one or more in number,

and these discs are also formed of flexible sheet material in the same manner as hereinabove described with respect to the valve diaphragms by punching and stamping operations with the internal stresses being relieved by a shot peening operation or the like. Thus, these discs 48 likewise have the ability of flexing under load while returning to their preshaped dished form when the load is removed or released.

Various modes of carrying out the invention are contem: plated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

We claim: I

I. In a discharge valve assembly for a reciprocating compressor having a cylinder end head with at least one high pressure dish discharge port therein, a flexible dish-shaped diaphragm plate disposed with its concave surface facing said end head and with a portion thereof overlying the discharge port, a flexible dish-shaped backup plate and means for attaching said diaphragm plate and backup plate to said end head in a manner whereby said diaphragm is flexed to flat condition to thereby seat and normally close the discharge port, said means including a spacer between the central portion of said plates, and a threadedmember extending through said head, plates and spacer for holding them in assembled relationship and flattening said diaphragm to overcome its inherent dish-shape to thereby provide a good seal.

2. A discharge valve assemblage according to claim 1, wherein the dish-shaped diaphragm plate is formed of nor-' mally flat sheet metal stock treated to relieve internal stresses resulting from the shaping thereof.

3. A discharge valve assemblage according to claim 2, wherein the treatment for relief of internal stresses is accomplished by a shot peening operation.

4. A discharge valve assemblage according to claim 3, wherein the surface of the diaphragm plate is roughened by the shot peening operation to provide a multiplicity of reservoirs therein.

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