Metal Reinforced Seal Plate for Pilot Actuated Spool Valve

Abstract

Upper and/or lower seal plates of a sub plate mounted, pilot actuated spool valve are reinforced with one or more metal rings. In a number of preferred embodiments, the metal ring is comprised of steel. Portions of the seal plates may comprise an engineering thermoplastic such as polyoxymethylene (POM) sold by E. I. DuPont de Nemours under the DELRIN® trademark. The plastic material may be molded to the metal ring. In other embodiments, the plastic material and metal ring(s) are mechanically connected together.

What is claimed is: 
     
         1 . A pilot-actuated spool valve comprising:
 a generally cylindrical cage having a central axial cavity open at both ends and a plurality of generally radial openings connecting the central axial cavity to the external cylindrical surface of the cage;   a spool sized to slide within the central axial cavity of the cage and having a first sealing surface at a first end and a second sealing surface at an opposing second end;   a seal configured to bear against the first sealing surface of the spool when the spool is at a first position within the central axial cavity of the cage and comprising a generally flat metal ring within an engineering thermoplastic disk having a central axial opening.   
     
     
         2 . A pilot-actuated spool valve as recited in  claim 1  wherein the generally flat metal ring is molded within the thermoplastic disk. 
     
     
         3 . A pilot-actuated spool valve as recited in  claim 2  wherein the metal ring is completely encased in the thermoplastic disk. 
     
     
         4 . A pilot-actuated spool valve as recited in  claim 1  further comprising a circumferential groove in the outer surface of the thermoplastic disk and a seal within the groove. 
     
     
         5 . A pilot-actuated spool valve as recited in  claim 1  further comprising a groove in the wall of the central axial opening in the thermoplastic disk and a seal within the groove 
     
     
         6 . A pilot-actuated spool valve as recited in  claim 1  further comprising a seal configured to bear against the second sealing surface of the spool when the spool is at a second position within the central axial cavity of the cage and comprising a generally flat metal ring within an engineering thermoplastic disk having a central axial opening. 
     
     
         7 . A pilot-actuated spool valve as recited in  claim 6  wherein the seal configured to bear against the second sealing surface of the spool comprises a generally flat metal ring encased in a thermoplastic disk. 
     
     
         8 . A pilot-actuated spool valve as recited in  claim 6  wherein the central axial opening in the seal configured to bear against the second sealing surface of the spool is internally threaded. 
     
     
         9 . A pilot-actuated spool valve as recited in  claim 1  wherein the thermoplastic disk is polyoxymethylene. 
     
     
         10 . A seal for a pilot-actuated spool valve comprising:
 a metal disk having a generally planar upper surface, a generally planar lower surface, a generally cylindrical outer surface and a central axial opening extending from the upper surface to the lower surface; an annular groove in the lower surface having a first, lesser width in a first portion adjacent the lower surface and a second, greater width in a portion remote from the lower surface; and   a thermoplastic insert in the annular groove having at least one generally planar surface that is substantially flush with the lower surface of the metal disk.   
     
     
         11 . A seal for a pilot-actuated spool valve as recited in  claim 10  wherein the central axial opening in the metal disk has a first portion adjacent the upper surface having a first inside diameter, a second portion adjacent the lower surface having a second inside diameter equal to the first inside diameter, and a third portion intermediate the first portion and the second portion having a third inside diameter greater than the first and second inside diameter. 
     
     
         12 . A seal for a pilot-actuated spool valve comprising:
 a metal disk having a generally planar upper surface, a generally planar lower surface, a generally cylindrical outer surface and a central axial opening extending from the upper surface to the lower surface;   an annular groove in the upper surface having a first, lesser width in a first portion adjacent the upper surface and a second, greater width in a portion remote from the upper surface; and   a thermoplastic insert in the annular groove having at least one generally planar surface that is substantially flush with the upper surface of the metal disk.   
     
     
         13 . A seal for a pilot-actuated spool valve as recited in  claim 12  wherein the central axial opening in the metal disk is internally threaded. 
     
     
         14 . A seal for a pilot-actuated spool valve comprising:
 a metal disk having a generally planar upper surface, a generally planar lower surface, a central axial opening extending from the upper surface to the lower surface and a stepped outer surface having a first portion with a first outside diameter and a second portion having a second outside diameter greater than the first outside diameter;   a metal ring having a generally planar upper surface, a generally planar lower surface, a central axial opening extending from the upper surface to the lower surface and having a first portion with a first inside diameter substantially equal to the first outside diameter of the metal disk and a second portion having a second inside diameter greater than the first inside diameter, the ring having first outer portion having a first thickness, a second, inner portion having a second thickness less than the first thickness and a third portion intermediate the first portion and the second portion having a third thickness less than the second thickness such that when the metal disk and metal ring are pressed together with an interference fit between the first portion of the metal disk and the first portion of the metal ring an annular cavity is formed between the metal disk and the metal ring open to the lower surface; and, a thermoplastic insert in the cavity having a surface substantially flush with the lower surface of the metal disk and metal ring.   
     
     
         15 . A seal for a pilot-actuated spool valve as recited in  claim 14  wherein the thermoplastic insert comprises polyoxymethylene. 
     
     
         16 . A seal for a pilot-actuated spool valve as recited in  claim 14  further comprising a groove in the upper surface of the thermoplastic insert and a seal within the groove. 
     
     
         17 . A seal for a pilot-actuated spool valve comprising:
 a metal disk having a generally planar upper surface, a generally planar lower surface, a central axial opening extending from the upper surface to the lower surface and an annular groove in the lower surface having a generally rectangular cross section such that the groove has an inner wall and an outer wall;   a first groove in the inner wall of the annular groove;   a second groove in the outer wall of the annular groove;   a ring-shaped thermoplastic insert within the annular groove having a generally T-shaped cross section with an inner shoulder and an outer shoulder;   a first keeper in the first groove in the inner wall of the annular groove which bears against the inner shoulder of the thermoplastic insert; and,   a second keeper in the second groove in the outer wall of the annular groove which bears against the outer shoulder of the thermoplastic insert.   
     
     
         18 . A seal for a pilot-actuated spool valve as recited in  claim 17  wherein the thermoplastic insert is formed of polyoxymethylene. 
     
     
         19 . A seal for a pilot-actuated spool valve as recited in  claim 17  where the first keeper is an outside spring clip. 
     
     
         20 . A seal for a pilot-actuated spool valve as recited in  claim 17  where the second keeper is an inside spring clip. 
     
     
         21 . A seal for a pilot-actuated spool valve as recited in  claim 17  further comprising an annular groove in the thermoplastic insert and a seal within the groove. 
     
     
         22 . A seal for a pilot-actuated spool valve comprising:
 a metal disk having a generally planar upper surface, a generally planar lower surface, a central axial opening extending from the upper surface to the lower surface and an annular groove in the lower surface having a generally rectangular cross section such that the groove has an inner wall and an outer wall;   external threads in a portion of the inner wall adjacent the lower surface of the metal disk;   internal threads in a portion of the outer wall adjacent the lower surface of the metal disk;   a ring-shaped thermoplastic insert within the annular groove having a generally T-shaped cross section with an inner shoulder and an outer shoulder;   a first metal ring having internal threads sized and spaced to engage the external threads in the portion of the inner wall adjacent the lower surface of the metal disk and bear against the inner shoulder of the thermoplastic insert; and   a second metal ring having external threads sized and spaced to engage the internal threads in the portion of the outer wall adjacent the lower surface of the metal disk and bear against the outer shoulder of the thermoplastic insert.   
     
     
         23 . A seal for a pilot-actuated spool valve as recited in  claim 22  wherein the thermoplastic insert is formed of polyoxymethylene. 
     
     
         24 . A seal for a pilot-actuated spool valve as recited in  claim 22  further comprising an annular groove in the thermoplastic insert and a seal within the groove. 
     
     
         25 . A seal for a pilot-actuated spool valve as recited in  claim 22  further comprising spanner holes in the metal disk, first metal ring and second metal ring. 
     
     
         26 . A seal for a pilot-actuated spool valve comprising:
 a metal disk having a generally planar upper surface, a generally planar lower surface, a central axial opening extending from the upper surface to the lower surface, a stepped outer circumference comprised of a first externally-threaded section proximate the upper surface and having a first larger outside diameter and a second unthreaded section proximate the lower surface and having a second smaller outside diameter;   a metal ring having an upper surface and a lower surface and a stepped inner surface with a first, internally threaded portion with a first larger inside diameter adjacent the upper surface and an unthreaded portion with a second smaller inside diameter adjacent the lower surface such that when the metal disk is screwed into the metal ring an annular cavity is created;   a ring-shaped thermoplastic insert having a shoulder on its outer circumference retained within the annular cavity on the stepped inner surface of the metal ring.   
     
     
         27 . A seal for a pilot-actuated spool valve as recited in  claim 26  wherein the thermoplastic insert is formed of polyoxymethylene. 
     
     
         28 . A seal for a pilot-actuated spool valve as recited in  claim 26  further comprising an annular groove in the thermoplastic insert and a seal within the groove. 
     
     
         29 . A seal for a pilot-actuated spool valve as recited in  claim 26  further comprising spanner holes in the metal disk and the metal ring. 
     
     
         30 . A seal for a pilot-actuated spool valve as recited in  claim 26  further comprising an O-ring seal between the thermoplastic insert and the metal ring. 
     
     
         31 . A seal for a pilot-actuated spool valve comprising:
 a metal disk having a generally planar upper surface, a generally planar lower surface, a central axial opening extending from the upper surface to the lower surface, and a plurality of countersunk through holes extending from the upper surface to the lower surface;   an annular projection on the lower surface of the metal disk having an outside diameter and an inside diameter;   a first metal ring having a stepped upper surface and a planar lower surface, an outside diameter equal to the outside diameter of the metal disk, a stepped inner surface with a first portion with a first larger inside diameter adjacent the upper surface and second portion with a second smaller inside diameter adjacent the lower surface and a plurality of threaded bores open to the upper surface;   a second metal ring having a stepped upper surface and a planar lower surface, an inside diameter equal to the inside diameter of the metal disk, a stepped outer surface with a first portion with a first smaller outside diameter adjacent the upper surface and second portion with a second larger outside diameter adjacent the lower surface and a plurality of threaded bores open to the upper surface;   a plurality of machine screws that pass through the through holes in the metal disk and engage the threaded bores in the first metal ring and the second metal ring such that the disk, first ring and second ring form an annular cavity open to the lower surface having a generally T-shaped cross section; and   a thermoplastic insert in the annular cavity having an exposed bottom surface planar with the lower surfaces of the first metal ring and second metal ring.   a ring-shaped thermoplastic insert having a shoulder on its outer circumference and a shoulder on its inner circumference retained within the annular cavity on the stepped inner surface of the outer metal ring and the stepped outer surface of the inner metal ring.   
     
     
         32 . A seal for a pilot-actuated spool valve as recited in  claim 31  wherein the thermoplastic insert is comprised of polyoxymethylene. 
     
     
         33 . A seal for a pilot-actuated spool valve as recited in  claim 31  wherein the annular projection on the metal disk together with the stepped upper surface of the first metal ring and the stepped upper surface of the second metal ring forms a rabbet joint. 
     
     
         34 . A seal for a pilot-actuated spool valve as recited in  claim 31  further comprising a first O-ring seal between the thermoplastic insert and the inner metal ring and a second O-ring seal between the thermoplastic insert and the outer metal ring. 
     
     
         35 . A seal for a pilot-actuated spool valve comprising:
 a metal disk having a generally planar upper surface, a generally planar lower surface, a central axial opening extending from the upper surface to the lower surface, and a plurality of countersunk through holes extending from the upper surface to the lower surface;   a first metal ring having a planar upper surface and a planar lower surface, an outside diameter equal to the outside diameter of the metal disk, a stepped inner surface with a first portion with a first larger inside diameter adjacent the upper surface and second portion with a second smaller inside diameter adjacent the lower surface and a plurality of threaded bores open to the upper surface;   a second metal ring having a planar upper surface and a planar lower surface, an inside diameter equal to the inside diameter of the metal disk, a stepped outer surface with a first portion with a first smaller outside diameter adjacent the upper surface and second portion with a second larger outside diameter adjacent the lower surface and a plurality of threaded bores open to the upper surface;   a plurality of machine screws that pass through the through holes in the metal disk and engage the threaded bores in the first metal ring and the second metal ring such that the disk, first ring and second ring form an annular cavity open to the lower surface having a generally T-shaped cross section; and   a thermoplastic insert in the annular cavity having an exposed bottom surface planar with the lower surfaces of the first metal ring and second metal ring.   a ring-shaped thermoplastic insert having a shoulder on its outer circumference and a shoulder on its inner circumference retained within the annular cavity on the stepped inner surface of the outer metal ring and the stepped outer surface of the inner metal ring.   
     
     
         36 . A seal for a pilot-actuated spool valve as recited in  claim 35  wherein the thermoplastic insert is comprised of polyoxymethylene. 
     
     
         37 . A seal for a pilot-actuated spool valve as recited in  claim 35  further comprising a first O-ring seal between the thermoplastic insert and the inner metal ring and a second O-ring seal between the thermoplastic insert and the outer metal ring.