US3683968A

US3683968A - Reverse-acting relay valve

Info

Publication number: US3683968A
Application number: US42377A
Authority: US
Inventors: Lloyd T Akeley
Original assignee: Beckman Instruments Inc
Current assignee: HAYS-REPUBLIC Corp A SUBSIDIARY OF OPTIMUM CONTROL CORPORATION AN OH CORP; Rosemount Inc
Priority date: 1970-06-01
Filing date: 1970-06-01
Publication date: 1972-08-15
Anticipated expiration: 1989-08-15
Also published as: DE2126794A1; GB1288525A

Abstract

A reverse-acting relay valve which employs a pressure responsive diaphragm driving an operably related pin. The pin contacts a throttling ball, moving it up and down as the diaphragm moves up and down. The diaphragm moves down with an increase in pressure and up with a decrease in pressure. Movement of the ball in the downward direction is limited by a supply seat, and movement of the ball in the upward direction is limited by an exhaust seat. When the ball is in its downward position, thus resting on the supply seat, flow through the relay is cut off. When the ball is in its upward position, thus against the exhaust seat, flow through the relay is at its greatest. When the ball is between the supply seat and the exhaust seat, some flow through the relay passes through the exhaust seat to a vent.

Description

United States Patent 9 Akeley [54] REVERSE-ACTING RELAY VALVE 1 Aug. 15, 1972 Primary Examiner-Alan Cohan Saint-Joanis l37/625.66

Atrorney--Williarn F. McDonald and Robert J. Steinmeyer [57] ABSTRACT A reverse-acting relay valve which employs a pressure responsive diaphragm driving an operably related pin. The pin contacts a throttling ball, moving it up and down as the diaphragm moves up and down; The diaphragm moves down with an increase in pressure and up with a decrease in pressure. Movement of the ball in the downward direction is limited by a supply seat, and movement of the ball in the upward direction is limited by an exhaust seat. When the ball is in its downward position, thus resting on the supply seat, flow through the relay is cut off. When the ball is in its upward position, thus against the exhaust seat, flow through the relay is at its greatest. When the ball is between the supply seat and the exhaust seat, some flow through the relay passes through the exhaust seat to a vent.

2 Claims, 3 Drawing Figures max Patented Aug. 15, 1972 2 Sheets-Sheet 1 FIG. I

INVENTOR.

LLOYD T. AKELEY ATTORNEY Patented Aug. 15, 1972 2 Sheets-Sheet 2 N 2i Pa INVENTOR.

LLOYD T. AKELEY ATTORNFY Rh me-norms unrnr vnrvr BACKGROUND OE THE llNVENTlON relays 3 l5 pounds per square inch pressure range, although some special systems use other pressure ranges. Signals are usually transmitted through relatively small bore tubing, with lengths varying from a few feet up to 2,000 feet or more. lPneumati-c indicators, controllers and transmitters typically have receiving end volumes up to approximately 5 cubic inches. Diaphragm or piston valve motors frequently have receiving end volumes ranging from about 100 to about 6,000 cubic inches equivalent volume. The system usually must respond to small relatively weak sigials of a few tenths of a pound per square inch or less.

Various manufacturers have different mechanical approaches to the problem, but the basic idea remains the same. The pneumatic relay produces a relatively strong output in the 3 to pounds per square inch range in response to the relatively weak input signal, for example from a measured variable. The receiver, in

an indicator or recorder or controller mechanism.

SUMMARY OF THE INVENTION It is an object of the instant invention to provide a pneumatic relay valve or amplifier wherein the bleed rate and gain and capacity of the relay valve can be adjusted as desired. Advantageously, the relay valve according to the instant invention shows improved stability and lower hysteresis in a smaller sized unit than con ventional relay valves.

According to the instant invention a reverse-acting relay valve is provided which includes a hollow housing and a partition having a centrally exposed bore therein positioned so as to divide the housing into a first and a second section. The bore provides communication between the two sections and an output passage extending outwardly from the bore through the housing. A pressure responsive diaphragm is positioned in the first section to divide it into two sub-sections, a first sub-section proximal the partition and a second subsection distal the partition. Means connect the distal sub-section to a fluid input and means also connect a fluid supply to the second section. Means are provided to vent the proximal sub-section to the atmosphere. A pin is operably related at one end to the diaphragm and extends therefrom through the proximal sub-section into the bore on one side of the output passage. An exhaust seat is provided in the surface of the bore between the output passage and the proximal sub-section. A throttling ball is positioned in the bore below the exhaust seat and is adapted to seat against the exhaust seat in the bore and to close communication between the proximal sub-section and the output passage and second section when the diaphragm flexes in one direction due to a decrease in pressure in the distal sub-section relative to the pressure in the proximal sub-section and to open communication when the diaphragm flexes in the other direction. A supply seat is positioned in the bore between the second section and the output passage and is adapted for the ball to seat against, closing communication with the second section, when the pin extends into the bore to the fullest position pushing the ball against the supply seat due to an increase in pressure in the distal sub-section relative to the pressure in the proximal sub-section. Means are provided for adjusting the distance between the supply and exhaust seats, whereby the bleed rate and gain and capacity of the relay are controlled.

BRIEF DESCRIPTION OF THE DRAWINGS H6. 11 is a schematic view with parts shown in section of a reverse-acting relay valve according to the instant invention.

HO. 2 is a schematic view with parts shown in section of another embodiment of the instant invention.

HO. 3 is an enlargement of the supply seat of the embodiment shown in F116. 2.

in all Figures, the same reference numerals have been applied to corresponding parts.

DETAILED DESCRIPTION Referring to HG. l it may be seen that the reverseacting relay valve of the instant invention includes a hollow housing indicated generally at 10. A central section l2 of housing l0 having a centrally disposed bore l4 therein is positioned so as to act as a partition and divide the housing into a first section 16 and a second section 1%. Bore l4 provides communication between the two sections, l6 and lid, andan output passage 20 extending outwardly from bore l4 through housing it). A pressure responsive diaphragm 22 is sealed in position as by gasket 23 in first section 16 to divide it into two subsections, a first or proximal sub-section 24 proximal partition 12 and a second or distal sub-section 2d distal partition l2. Means such as access 27 and line 2% connect distal subsection 26 to a source of fluid input pressure not shown. Means such as supply line 30 connect a fluid supply to second section 18. Means such as vent opening 34? vent proximal sub-section 24 to the atmosphere. A second gasket 23 seals second section id to partition l2. I

Pin 36 is operably related at one end 38, shown as of an enlarged T-shaped cross section, to diaphragm 22 and extends therefrom through proximal sub-section 24 into bore M on one side of output passage 20. End 38 has a dimple 39 therein which mates with a bump 4 on diaphragm 22 to center pin 36. An exhaust seat indicated generally at d0 is provided in the surface of bore lid between output passage 20 and proximal subsection 2d. A throttling ball 46 is positioned in bore 14 below exhaust seat 40 and the other end 44 of pin 36 and is adapted to seat against exhaust seat 40 in bore M and to close communication between proximal sub-section 24 and output passage 20 and second section 18 when diaphragm 22 flexes in one direction (the upward direction as shown) due to a decrease in pressure (P,) in the distal sub-section 26 relative to the pressure (P,,) in proximal sub-section 2d and to open communication when diaphragm 22 flexes in the other direction.

A supply seat indicated generally at i8 is positioned in bore lid between second section lb and output passage 20 and has a seating surface adapted for ball dd to seat against, closing communication with second section id when pin 36 extends into bore M to the fullest position pushing ball 46 against seating surface 869 of supply seat 48 due to an increase in pressure in distal sub-section 26 relative'to the pressure in proximal subsection 24. Means such as coacting screw threads 5i and 52 are provided on the surface of bore 114 and supply seat 48 for adjusting the distance between supply seat 48 and exhaust seat 40. In this way the full travel of ball 46 can be adjusted to achieve a desired gain or bleed rate. O-ring 53 provides a seal and mechanical locking action between supply seat 48 and bore 14. Ball 46 moves in bore 14 between exhaust seat 40 and supply seat 48 in response to input pressure P to provide output pressure P, proportional to input pressure P In the embodiment shown in MG. 2 a spring bias element 56 is positioned between end 38 of pin 36, which is in contact with diaphragm 22, and partition 12. Spring bias element 56 adds a force bias to the natural spring action of the diaphragm. A restrictor 58 is provided in line 28, which is connected to line 3%, so that the pressure P in distal sub-section 26 is less than but related to the input pressure P, in fluid supply line 30 and second section 18. The pressure P in distal subsection 26 is further controlled by a flapper 6i) acting on nozzle valve 62. The position of flapper 64) may be determined by a measuring system or set in other appropriate manners and controls the escape of fluid, e.g., air, through nozzle 62 to maintain P at a desired level.

In the embodiment shown in FIG. 2, and referring to FIG. 3 where it may be seen more clearly, supply seat 48 is shown as an assembly including an outer sleeve 64 adjustably positioned in bore 34 and having inwardly extending shoulders 66 at end 70 extending into bore 14 (its inner end) and 68 at its outer end 72. An inner sleeve 74 having an outwardly extending shoulder 76 at its inner end 78 is positioned with shoulder 76 between

shoulders

66 and 68 of outer sleeve 64 so that inner sleeve 74 can slide relative to outer sleeve 64. Seating surface 80 is provided on inner end 78 of inner sleeve 74. Spring biasing means 82 are positioned between shoulder 68, shown formed by a ring staked into outer sleeve 64, and shoulder 76 at the inner end 78 of inner sleeve 74 for biasing inner sleeve 74 toward shoulder 66. .If desired, an O-ring 53 may be used to hold the supply seat 48 assembly in position after it has been adjusted. This arrangement makes the position of seating surface 80 adjustable under the force exerted thereupon by ball 46 and makes possible the utilization of further travel of ball 46 to achieve the highest possible exhaust capacity through exhaust seat 4h when needed.

Referring again to FIG. 2, end 44 of pin 36 has a frustoconical cross-section. Exhaust seat 48 includes a throttling surface 84 in bore l4 having a taper matching that of frusto-conical end 44 of pin 36. A shoulder 54 is also part of exhaust seat 4@ and is positioned for ball 46 to seat against when diaphragm 22 flexes in one direction clue to a decrease in pressure P in distal sub-section 26 relative to the pressure P in proximal sub-section 24.

The operation of the reverse-acting relay according to the instant invention may be briefly described. Diaphragm 22 responds to the difference between the pressure P, in distal sub-section 26, which may be regarded as the control pressure, and the pressure P in proximal sub-section 24 to move pin 36 which contacts throttling ball 46 moving it up and down as diaphragm 22 moves up and down. Diaphragm 22 moves down with an increase in pressure P which, as shown in FIG. 2, may be related to the supply pressure P, in supply line 30, and up with a decrease in pressure P Proximal sub-section 24 is vented to atmosphere by vent 34 so that P is essentially a constant reference pressure, atmospheric pressure. The movement of ball 46 in the downward direction is limited by supply seat 48 and movement of ball 46 in the upward direction is limited by shoulder 54 on exhaust seat 40. When ball 46 is in its downward position, resting on supply seat 48, e.g. the seating surface 80 of supply seat 48, flow through the relay is cut off. When ball 46 is in its upwardmost position and thus against shoulder 54 and in the FIG. 2 embodiment, end 44 is against throttling surface 84 of exhaust seat 40, flow through the relay to output passage 20 is at its greatest. When ball 46 is between supply seat 48 and exhaust seat 40, some fluid passes through exhaust seat 40 and hence out through vent 34. The position of supply seat 48 is adjustable so that the full travel of ball 46 can be adjusted to achieve a desired gain and bleed rate. The small section of pin 36 achieves large clearance to surface 84 for high demand exhaust capacity and the matching tapers of end 44 and throttling surface 84 center pin 36 in exhaust seat 40 when the ball 46 is seated against shoulder 54 so that pin 36 does not rub and produce hysteresis in the operating range.

The relationship is such that the steady state output pressure P in output passage 20 will decrease as P in distal sub-section 26 increases. In the normal operating range with l varying from 3 to 15 pounds per square inch with a supply pressure P, equal to 20 pounds per square inch, ball 46 will move only slightly, never seating on either exhaust seat 40 or supply seat 48. In a typical arrangement, P varies from about 3.5 to 3.0 pounds per square inch, and P in response thereto varies from 3 to 15 pounds per square inch. This is the general arrangement shown in FIG. 2. If P is reduced well below its normal operating range, for example by opening flapper 60, nozzle valve 62 assembly to the maximum extent, then ball 46 moves against shoulder 54 on exhaust seat 40 and in conjunction with end 44 and throttling surface 84 shuts OK the exhaust flow into proximal sub-section 24. This results in a maximum flow from second section 18, which is at pressure P,, the supply pressure, to the output and results in a maximum output pressure P,. If P should increase to well above its normal operating range, ball 46 will seat against supply seat 48 shutting oh the supply pressure P, and increasing the clearance through exhaust seat 40 to achieve the maximum exhaust flow capacity.

The maximum supply and exhaust capacities are functions of total ball 46 travel and hence the adjustability of the position of supply seat 48 can be utilized to adjust the maximum supply and exhaust capacity. The resiliency of the supply seat assembly 48 shown in FIG. 2 can be utilized to achieve the highest possible exhaust capacity when necessary.

The embodiment of FIG. 1. is simple to manufacture and, having few parts and large clearances, provides relatively trouble-free service. For most applications it provides a satisfactory combination of performance characteristics. The stiflness of diaphragm 22 and the travel of ball 46 determine the gain of the relay. The bleed rate and supply and exhaust capacity depend upon ball and bore dimensions and the diametrical clearance between pin 36 and seat 40 as well as ball travel adjustment, as is apparent to those skilled in the art. If pin 36 rubs on seat 40 or bore 14, the resulting friction increases the hysteresis in the relay operation.

The embodiment of FIG. 2 minimizes operating bleed rate without sacrificing supply and exhaust capacity. When the lowest possible bleed rate is required this construction is preferred even though the smaller clearances and increased complexity may make this embodiment more difficult to maintain. Spring 56 adds a force bias to the natural spring action of diaphragm 22. With this combination the diaphragm stiffness can be reduced to favor optimum linearity of output versus input. Flapper 60, nozzle valve 62 and flow restrictor 58 are often used with a relay valve in a force-balance instrument such as a force balance differential pressure transmitter. Flow restrictor 58 is usually built into the base of the relay and flapper 60, nozzle 62 assembly is the position detector which controls the pressure P to the relay, whose output pressure P feeds a feedback bellows to maintain force balance.

It will be appreciated that the foregoing is only a description of some representative forms of apparatus embodying the principles of the instant invention. This is for illustrative purposes and the instant invention is defined by the claims,

Wherein what is claimed is: 1. A reverse-acting relay valve comprising: a. a hollow housing; y b. a partition having a centrally disposed bore therein positioned so as to divide the housing into a first and a second section, the bore providing communication between the two sections and an output passage extending outwardly from the bore through the housing; a pressure responsive diaphragm positioned in the first section to divide it into two sub-sections, a

first sub-section proximal the partition and a and extending therefrom to its other end through the proximal sub-section into the bore on one side of the output passage;

an exhaust seat in. the surface of the bore between the output passage and the proximal sub-section;

i. a throttling ball positioned in the bore below the exhaust seat and the other end of the pin, unattached to the pin and adapted to seat against the exhaust seat in the bore and! to close communication between proximal sub-section and the output passage and second section when the diaphragm flexes in one direction due to a decrease in pressure in the distal sub-section relative to the pressure in the proximal sub-section and to open communication when the diaphragm flexes in the other directi J. a supp y seat positioned in the bore between the second section and the output passage including an outer sleeve adjustably positioned in the bore and having inwardly extending shoulders at its end extending to the bore and at :its outer end, an inner sleeve having an outwardly extending shoulder at its inner end positioned between the shoulders of the outer sleeve so that the inner sleeve can slide relative to the outer sleeve, a seating surface on the inner end of the inner sleeve, and spring biasing means positioned between the shoulder at the outer end of the outer sleeve and the shoulder at the inner end of the inner sleeve for biasing the inner sleeve toward the shoulder at the end of the outer sleeve extending into the bore, said supply seat adapted for the ball to seat against, closing communication with the second section, when the pin extends into the bore to the fullest position pushing the ball against the supply seat due to an increase in pressure in the distal sub-section relative to the pressure in the proximal sub-section; and

k. means for adjusting the distance between the supply and exhaust seats, whereby the gain and capacity of the relay are controlled.

2. The reverse-acting relay of claim 1 wherein the end of the pin extending into the bore has a frustoconical cross section and the exhaust seat comprises a throttling surface in the bore having a taper matching that of the frustoconical ends of the pin, and a shoulder positioned for the ballto seat thereagainst when the diaphragm flexes in one direction due to a decrease in pressure in the distal sub-section relative to the pressure in the proximal sub-section.

Claims

1. A reverse-acting relay valve comprising: a. a hollow housing; b. a partition having a centrally disposed bore therein positioned so as to divide the housing into a first and a second section, the bore providing communication between the two sections and an output passage extending outwardly from the bore through the housing; c. a pressure responsive diaphragm positioned in the first section to divide it into two sub-sections, a first sub-section proximal the partition and a second sub-section distal the partition; d. means connecting the distal sub-section to a fluid input from a fluid supply; e. means connecting the fluid supply to the second section; f. means venting the proximal sub-section to the atmosphere; g. a pin operably related at one end to the diaphragm and extending therefrom to its other end through the proximal subsection into the bore on one side of the output passage; h. an exhaust seat in the surface of the bore between the output passage and the proximal sub-section; i. a throttling ball positioned in the bore below the exhaust seat and the other end of the pin, unattached to the pin and adapted to seat against the exhaust seat in the bore and to close communication between proximal sub-section and the output passage and second section when the diaphragm flexes in one direction due to a decrease in pressure in the distal subsection relative to the pressure in the proximal sub-section and to open communication when the diaphragm flexes in the other direction; j. a supply seat positioned in the bore between the second section and the output passage including an outer sleeve adjustably positioned in the bore and having inwardly extending shoulders at its end extending to the bore and at its outer end, an inner sleeve having an outwardly extending shoulder at its inner end positioned between the shoulders of the outer sleeve so that the inner sleeve can slide relative to the outer sleeve, a seating surface on the inner end of the inner sleeve, and spring biasing means positioned between the shoulder at the outer end of the outer sleeve and the shoulder at the inner end of the inner sleeve for biasing the inner sleeve toward the shoulder at the end of the outer sleeve extending into the bore, said supply seat adapted for the ball to seat against, closing communication with the second section, when the pin extends into the bore to the fullest position pushing the ball against the supply seat due to an increase in pressure in the distal sub-section relative to the pressure in the proximal sub-section; and k. means for adjusting the distance between the supply and exhaust seats, whereby the gain and capacity of the relay are controlled.

2. The reverse-acting relay of claim 1 wherein the end of the pin extending into the bore has a frustoconical cross section and the exhaust seat comprises a throttling surface in the bore having a taper matching that of the frustoconical ends of the pin, and a shoulder positioned for the ball to seat thereagainst when the diaphragm flexes in one direction due to a decrease in pressure in the distal sub-section relative to the pressure in the proximal sub-section.