AU632212B2 - Improved multiple-ring compressor valve - Google Patents

Description

5010 :Y 632212 Our Ref: 359151

AUSTRALIA

Patents Act COMPLETE SPECIFICATION FORM

(ORIGINAL)

Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: Applicant(s): Address for Service: Garlock Pty Ltd Willis Street ARNCLIFFE NSW 2205

AUSTRALIA

ARTHUR S. CAVE CO.

Patent Trade Mark Attorneys Level 10, 10 Barrack Street SYDNEY NSW 2000 Complete specification for the invention entitled "Improved multiple-ring compressor valve".

The following statement is a full description of this invention, including the best method of performing it known to me:- 1 5020 I~ rlC- I r 'i r i z c set ri la IMPROVED MULTIPLE-RING COMPRESSOR VALVE FIELD OF THE INVENTION This invention relates generally to an improved form of compressor valve used with reciprocating gas compressors, and more particularly to such a valve having multiple valve rings of different axial dimension thickness).

BACKGROUND OF THE INVENTION Reciprocating gas compressors typically have one or more suction inlet) valves and one or more outlet (i.e.

discharge) valves to control the flow of gas through the compressor cylinder. These valves function in the nature of check valves to limit the flow of gas to one direction only.

Accordingly, the suction valve permits the flow of gas into the cylinder, while the outlet valve permits flow of gas out of the cylinder. The same valve design, properly oriented, may be used i -2for either inlet or outlet applications.

The known designs of multiple ring compressor valves embody a valve seat or plate, a plurality of valve rings which engage mating openings in the valve seat and a valve guard which mates with the valve seat to form a housing, enclosing and positioning the valve rings. One axial end face of each ring defines a sealing surface which is aligned with an opening in the valve seat and which is dimensioned to engage a mating surface of the seat around the periphery of the opening. Each ring is mounted for movement toward and away from the valve seat so that when the ring is abutted against the seat, it forms a closure precluding the flow of gas through the opening. Biasing springs are generally provided for urging the rings into abutting relationship with- the seat to maintain a "normally closed" position.

In operation, the valves are positioned so that increased air -3pressure acting on the surface of the ring, through an opening in the seat, overcomes the force of the biasing spring and urges the ring away from the seat into an "open" position. For inlet or suction valve applications, incoming or "ambient" air represents increased air pressure. Accordingly, for inlet applications, the valve guard side of the valve is oriented S toward the interior of the compressor cylinder which is at lower pressure during the inlet stroke. For outlet or discharge applications, the orientation is reversed and the valve seat ,,,Iside of the valve faces the interior which is at higher pressure tee f during the outlet stroke.

Multiple ring compressor valves of the type described in the S preceding paragraphs are well known in the gas compressor art.

A plurality of concentrically positioned ring elements are arranged in a generally planar relationship on the seating surface of the valve seat member. A plurality of apertures in -4the seat are axially aligned with the rings.

In the early prior art design of such valves, the multiple rings were uniformly flat and of uniform thickness. Various economic and functional requirements were thought to necessitate this configuration. More recently, in some designs, a contoured face has been formed on the mating surface of the valve ring which abuts against the valve seat, to improve the control of Sgas flow through the apertures in the seat. However, even in this known contoured-face design, each ring in a multiple ring S valve is characterized by an identical radial cross-section, and the thickness or length of each ring in the axial direction is equal to the thickness of every other ring. This design Sc' convention was adhered to because it greatly simplified manufacturing techniques, it reduced, manufacturing costs and it was believed that variations in the axial length dimensions among the different rings were not advantageous.

i I i Over the course of time, and as experience has been gained in the use of multiple ring valves, it has been noticed that the larger diameter outer rings routinely experience a significantly higher incidence of breakage and general failure. This is now believed to be attributable to material "fatigue" resulting in 9* Spart from at least two significant factors: 1) the outer rings are subjected to a significantly higher total number of high speed "impacts" with gasborne particles as a direct result of the larger total surface area of these rings, and these "impacts" tend to induce high-frequency vibrations in the ring structure; and 2) the outer rings are generally less rigid than the smaller inner rings and therefore are subject to a greater range of flexing and flex-induced stress during normal opening and closing operations.

SUMMARY OF THE INVENTION In accordance with the present invention, it has been S: LLI 1.

i -6discovered that the higher incidence of failure in the outer rings is controllable and reducible, so that the anticipated or normal "wear life" of all of the rings in such multiple array can be made much more nearly equal. It is desirable for all of the rings to wear evenly, so that they may be replaced at the o *1 same time, for obvious economic and practical advantages. A feature of this invention embodies multiple rings within a given valve assembly, having differing axial thickness dimensions, with the innermost ring being thinner than the outermost ring and any intermediate rings being of relatively intermediate t r thickness.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects, features and advantages of this invention will be made apparent to those having skill in this art, by reference to the following specification and the accompanying drawings, in which: s -7- Fig. 1 is an exploded perspective view, partially in crosssection, of a multiple ring compressor valve in accordance with a preferred embodiment of this invention; Fig. 2 is a cross-sectional view of a valve ring member which forms part of the assembly of Fig. 1, marked to illustrate r dimensional details of its construction; and Fig. 3 is a side cross-sectional view (partially cut-away?) showing the valve of Fig. 1 in its assembled and closed position.

DETAILED DESCRIPTION OF THE INVENTION Referring now more particularly to the drawings, the disclosed embodiment of a multiple ring valve 10 may be seen in Fig. 1 1 comprise a valve seat 12 (also sometimes called a valve plate), a valve guard 14 and a bolt 16 which holds the guard 14 and the seat 12 together in assembled relationship. A plurality of valve rings 18 ai'e positioned between the valve -8seat 12 and the valve guard 14, and are resiliently supported on the guard 14 by a plurality of helical compression springs Each ring 18 is of uniform cross-sectional shape throughout its circumference and all of the rings 18 are of the same geometric form in cross-section, although each successively larger diameter ring is of greater axial extent or height The seat 12 incorporates a plurality of apertures 22 disposed in concentric circular arrays 24 around a central axis represented in this embodiment by bolt 16. On the inner face 26 of seat 12, the apertures 22 each terminate in one of a series of concentric circular grooves 28. The grooves 28 are coaxially aligned with mating surfaces of the valve ring members 18, to control the flow of gases through the apertures 22 in a manner which is described in greater detail elsewhere in this specification.

The valve guard 14 is generally coextensive in diameter with -9valve seat 12 so that a composite laminated disk assembly is formed when the seat 12 is fastened to the guard 14. Fastening together of these two elements is accomplished by means of threaded bolt 16, which extends through a central bore 30 in seat 12 and threadedly engages threaded bore 32 centrally located in guard 14. A plurality of axially extending lugs 34 positioned around the outer periphery of guard 14, extend toward seat 12 from the inner face 36 of the valve guard 14. The lugs 34 engage inner face 26 of seat 12 to maintain the seat and the guard, in the desired, parallel spaced-apart relationship when the two parts are drawn together by bolt 16. The space between face 36 of guard 14 and face 26 of seat 12 defines a chamber for containing the valve rings 18 and resilient valve ring support springs 20 in operative, displaceable relationship.

Valve guard 14 further includes a plurality of through passages 40 for perm:tting flow of gas through the guard 14 and I i: out of the valve assembly. The passages 40 are of generally arcuate shape, disposed in concentric circular arrays. However, the passages 40 may have any desired shape and may be disposed in any desired pattern which is consistent with permitting adequate gas flow and which allows for adequate structural strength of the guard 14 as well as for proper positioning of t the supporting valve springs Also, as shown in the embodiment of Fig. 1, a plurality of 2, receiving bores 42 are recessed into the guard 14 to receive and support the helical valve springs 20. The inner diameter of each bore 42 is selected to accommodate the. outer diameter of .each spring 20, so that the springs may compress and extend freely without binding or undue lateral deflection. Each spring is capped with a valve button 44 which may be of plastic, metal or other suitable material and which is coupled to the spring in any suitable known manner, as for example, by forcetnr~l^-rri*-ar~~l~-- -11fitting an axial portion of the button within the inner diameter of the spring. The valve buttons 44 serve at least two different purposes in the valve assembly: 1) they provide a transition bearing surface between an axiail end of spring 20 and end surface 19 of ring member 18, to distribute spring force over a greater area of the ring surface, and 2) the axial length of each button may be selected to accommodate variations in the cross-sectional height of rings 18 to assure that they are supported in proper position relative to sealing grooves 28 in seat 12. In a preferred form, the combined axial extent or "stack height" of each assembly of rings 18, buttons 44 an, springs 20 will be the same. This will allow the grooves 28 of valve seat 12 to be of uniform depth and similarly, the bores 42 of guard 14 may also be of uniform depth. In this manner, fabrication of seat 12 and guard 14 is simplified and less costly.

-12- Reference to Fig. 2 is useful in understanding a preferred axial thickness relationship between the concentric array of valve rings. Thus, each of the valve rings 18 of a preferred embodiment has a cross-section corresponding to a rectangular body portion 50 plus a nose portion comprising an isosceles triangle and more preferably a right isosceles triangle. The base of the triangle corresponds to one of the longer sides of the rectangle, as shown in dotted lines, and the minimum body height (length of the shorter side) of the rectangle of the smallest diameter ring 18 is not substantially less than 0.125" (2.9 mm) A preferred ody height for each of the larger diameter rings 18 may be calculated by multiplying the body height of the smallest ring by the ratio of the mean diameter of each of the larger rings to the mean diameter of the smallest ring. The triangular portion is not involved in the calculation, and thus, the same formula may be used to calculate -13preferred thicknesses for each of an array of rectangular crosssection rings or rings of any other desired cross-section. In the preferred pyramidal or pentagonal cross-section of Fig. 1, the overall axial dimension will be equal to the body portion height plus the height of the triangular nose portion.

In operation of a compresFor, the valve rings 18 move between the open and closed positions in the same manner as described previously in relation to the prior art. Thus, in Fig 3 which shows a fully assembled valve, the valve rings 18 are shown with sealing surfaces 46 in sealing engagement with beveled or chamfered surfaces 38 of valve seat 12. Preferably, the angle of surfaces 46 is substantially equal to the angle of surfaces 38, all relative to a common horizontal plane. Even more preferably, these angles are about Also in Fig. 3, the left side of the largest diameter valve ring 18 is shown in its open position by dotted lines. It is 1 5020 -14noted that even in the open position, the nose 48 of ring 18 is within the axial extent of groove 28. Thus, even if ring 18 moves laterally, any such movement will be limited by engagement at some point of nose portion 48 with radially inner or outer chamfered surface 38 of valve seat 12. If fully rectangular valve rings are to be used, other means such as pins, must be employed to avoid excessive lateral movement of such valve rings.

While preferred embodiments of the invention have been shown and described in detail, other modifications will be readily apparent to those skilled in the art of compressor valves.

Thus, the preceding specification should be interpreted as exemplary rather than as limiting and the scope of the invention is defined by the following claims.

Claims (9)

1. A multiple ring compressor valve assembly comprising: a valve seat having a plurality of apertures therethrough located in a plurality of concentric circular arrays; a valve guard having openings therein for permitti.ng passage of gas therethrough, said guard being positioned in substantially parallel, spaced-apart, coaxial relationship with said valve seat to define a ring chamber the~rbetween; means holding said seat and said guard in said spaced-apart relationship; and a concentric array of substantially circular individual valve rings resiliently supported within said ring chamber, in alignment with each of said concentric circular arrays of apertures in said valve seat, each ring being resiliently moveable toward and away from sealing engagement with said valve seat so as to obstruct passage of gas through said apertures when said rings are engaged with said valve seat; wherein, each ring has a substantially uniform cross- I f sectional shape throughout its circumference, and one axial end face of said ring is configured to engage said valve I. .tt: seat in sealing relationship; and wherein, said concentric array of successively larger diameter valve rings comprises a plurality of rings, each of which is substantially equal in radial dimension and each of which is of greater cross-sectional height in its axial direction than the next smaller diameter ring.

2. A multiple ring compressor valve in accordance with Claim 1, wherein: each of said valve rings has a rectangular body portion and the height of the rectangular body portion of each larger diameter ring of said concentric array is greater than the corresponding height of the least diameter ring of said array and equal to the product of a constant equal to the rectangular body portion height of said least diameter ring multiplied by the ratio of the mean diameter of said larger diameter ring to the mean diameter of said least diameter ring. 0387p:mmb 16

3. A multiple ring compressor valve in accordance with Claim 2, wherein: the cross-sectional configuration of said rings corresponds to a triangular nose portion surmounting a rectangular body portion in which the triangle is an isosceles triangle and the base of the triangle is coincident with and equal to the width of the rectangle measured along the radial direction of said rings.

4. A multiple ring compressor valve in accordance with Claim 3, wherein the isosceles triangle is also a right triangle. A multiple ring compressor valve in accordance with Claim 1, wherein the valve ratings are of rectangular cross- section and the least height of any valve ring is not substantially less than 0.125" (2.9 mm).

6. A multiple ring compressor valve of the type having an array of at least two concentric annular valve rings of successively larger diameter and all having the same geometric form, and wherein each successively larger diameter valve ring has a greater axial thickness.

7. A compressor valve according to Claim 6, wherein the cross-sectional configuration of said valve rings corresponds to a triangular nose portion surmounting a rectangular body portion, in which the triangle is an isosceles triangle and the base of said triangle is coincident with and equal to the width of the rectangle ':..measui=d along the radial direction of the valve rings; and the height of the rectangular body portion of the least diameter ring is not substantially less than 0.125" (2.9 mm).

8. A compressor valve according to Claim 7, wherein the isosceles triangle is also a right triangle.

9. A compressor valve according to Claim 6, wherein the valve rings are of rectangular cross-section and the least height of the least diameter valve ring is not substantially less than 0,125" (2.9 mm). A multiple ring compressor valve assembly substantially .1 as hereinbefore described with reference to the accompanying |i drawings. 0387p:mmb 17

11. A multiple ring compressor valve substantially as hereinbefore described with reference to the accompanying drawings. DATED this 19th day of August, 1992. GARLOCK PTY LTD By Its Patent Attorneys DAVIES COLLISON CAVE Ir p 0 S