EP0256114A1

EP0256114A1 - Fluid pressure regulation and method

Info

Publication number: EP0256114A1
Application number: EP87901808A
Authority: EP
Inventors: Paul George Eidsmore
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-02-04
Filing date: 1987-02-04
Publication date: 1988-02-24
Also published as: EP0256114A4; AU7034387A; IE870293L; DK517687A; GB2193559A; JPS63502699A; CN87102162A; FI874325A0; GB8723263D0; ZA87799B; FI874325A; IT8719258A0; IT1216874B; DK517687D0; GB2193559B; NO874114D0; MX171410B; NO874114L; WO1987004765A1

Abstract

Procédé et dispositif améliorés de régulation d'une pression, répondant aux conditions de pression agissant sur un soufflet pressurisé (37) situé en aval du joint de pression (25). Les paramètres de conception sont indiqués pour établir un léger écart dans la régulation stable pour fournir une indication proportionnelle de la pression d'alimentation et par conséquent le volume de gaz disponible dans un cylindre d'alimentation (81). Deux versions du régulateur (9, 61) sont décrites, et un appareil de filtration (77) est prévu à l'extrémité d'admission (63) du régulateur pour assurer un fonctionnement convenable sans avoir recours à des connecteurs additionnels à haute pression.Improved method and device for regulating a pressure, meeting the pressure conditions acting on a pressurized bellows (37) located downstream of the pressure seal (25). The design parameters are indicated to establish a slight deviation in stable regulation to provide a proportional indication of the supply pressure and therefore the volume of gas available in a supply cylinder (81). Two versions of the regulator (9, 61) are described, and a filtration apparatus (77) is provided at the intake end (63) of the regulator to ensure proper operation without the need for additional high pressure connectors.

Description

FLUID PRESSURE REGULATION AND METHOD

Cross-Reference to Related Applications This application is a continuation-in-part application of pending application Serial No. 826,022 entitled FLUID FLOW ISOLATION AND CONTROL APPARATUS AND METHOD which is a continuation-in-part application of pending application Serial No. 675,825 entitled FLUID FLOW CONTROL VALVE AND METHOD.

Background and Summary of the Invention Systems which operate with fluids under pressure commonly require pressure regulators to assure that fluid from a source under high pressure is supplied to the system at low, substantially steady pressure, independently of variations in the fluid pressure at the source. In gas systems which are supplied, for example, from a cylinder of compressed gas at extremely high pressures, it is common practice to install a pressure regulator following the shut-off valve on the cylinder to minimize the portions of the system that operate at potentially hazardous high pressures, and to assure a supply of the compressed gas at substantially steady, low pressure despite the drop in pressure of the gas in the cylinder as the gas is released or used up over time. However, since the volume of gas within a cylinder is directly related to the gas pressure at a given temperature, it is common practice to install a high-pressure gage between the shut-off valve on the cylinder and the pressure regulator to provide an indication of supply pressure and, hence, of volume of gas in the cylinder.

In accordance with the present invention, a pressure regulator includes a pressure-responsive bellows that is disposed to operate a valve seal in controlled manner in response to fluid pressure acting upon the bellows at a location downstream of the valve seal. In addition, pressure regulation according to the present invention establishes an inverse relationship between gas volume remaining in the cylinder and the regulated outlet pressure so that only low-pressure metering is required to obtain indication of the volume of gas remaining in a supply cylinder. This obviates the need for high-pressure metering, with associated hazards of rupture and leak at a location upstream of the pressure regulator, and permits direct coupling of the regulator to the shut-off valve of the cylinder to minimize the potentially hazardous portions of the system that operate at high pressures. Also, an integral filtration system is included wichin the connector fittings to reduce the number of high-pressure connections subject to leaks or failure and to permit convenient change of filter each time a new supply cylinder is connected to the regulator. Description of the Drawings Figure 1 is a cross-sectional view of one embodiment of a generally cylindrically-shaped regulator according to the present invention illustrated operating under an extreme condition of high outlet pressure;

Figure 2 is a cross-sectional view of the embodiment illustrated in Figure 1 operating under the extreme condition of low outlet pressure;

Figure 3 is a cross-sectional view of the illustrated embodiment of Figure 1 showing a modification to the bellows for controlling the regulation pressure;

Figure 4 is a cross-sectional view of another embodiment of the pressure regulator of the present invention which is generally cylindrically-shaped in coaxial configuration and which is illustrated operating in an extreme condition of low outlet pressure;

Figure 5 is a cross-sectional view of the embodiment of Figure 4 illustrated operating in an extreme condition of high outlet pressure; Figure 6 is a pictorial diagram of a gas-pressure system assembled according to the present invention; and

Figure 7 is a graph showing the inverse deviation of regulated outlet pressure as a function of inlet pressure which facilitates low-pressure monitoring of remaining gas volume in a supply cylinder. Descripfion of the Preferred Embodiment Referring now to Figure 1, there is shown a cross- sectional view of one embodiment of the pressure regulator according to the present invention. The regulator body 9 is generally cylindrical with inlet port 11 and outlet port 13 sealed to the body, for example, by electron-beam welding techniques to assure integral, leak-free attachment to the body 9. Conventional high-pressure fittings (not shown) may be provided on inlet and outlet ports 11, 13 for convenient attachment to other fluid connectors of the system. The body 9 includes a seal seat 15 around aperture 17 that connects the inlet chamber 19 associated with inlet port 11 to the outlet chamber 21 associated with the outlet port 13. A generally cylindrical piston 23 is slidably disposed within the inlet chamber 19 to move in a direction into and away from sealing engagement with the seal seat 15. An elastomeric seal 25 may be attached to the piston 23, for example, by casting or cold-rolling a flange inwardly over the seal, to assure fluid-tight sealing engagement with the seal seat 15. The seal 25 may be formed of perfluoroelastomer (available as Kalrez from DuPont Co.), or other suitable chemically-inert elastomer. The piston 23 also carries a central rod 27 which protudes through the aperture 17 into the outlet chamber, and also carries a permanent magnet 29 encapsulated within the body of the piston 23. The inlet chamber 19 is sealed with an end cap 31 that also encapsules a permanent magnet 33 therein in magnetic-repulsion orientation with respect to magnet 29. The seal between body 9 and end cap 31 may also be formed by beam-welding techniques, or the like (after the parts are assembled within the inlet chamber 19) to eliminate the possibilities of gas leaks into the environment. Thus, with the magnets 29 and 33 oriented to repel, the piston 23 and seal 25 are urged into normally--closed, sealing engagement with seal seat 15, and the rod 27 protrudes through the aperture into the outlet chamber 21. This sealing engagement is enhanced by pressure of the fluid at inlet port 11 acting on an area of the piston approximately equal to the area of aperture 17. Of course, the piston 23 and seal 25 may be urged into sealing engagement with surface 15 by a spring instead of the repelling magnets 29 and 33.

In the outlet chamber 21, there is a pressure-responsive controller 35 comprising a generally cylindrical bellows 37 sealed to end caps 39 and 41 to form an expandable pressure vessel. The end cap 41 is disposed to contact the rod 27 which protrudes through the aperture 17, and the end cap 39 is sealed to the body 9, for example, by electron-beam welding techniques, or the like. Thus, the parts of the regulator which are to be sealed against pressure leaks may all be formed of such bondable materials as aluminum, stainless steel, plastics, and the like, which also do not significantly effect the magnetic flux of magnets 29 and 33. The end caps 39 and 41 are internally dimensioned to prevent over-compression of the bellows at the limit of surfaces 43 and 45 coming into contact. Also, the end cap 39 includes an elastomeric ball 47 disposed within an inner recess of channel 49 to serve as a temporary check valve until the ball 51 in the outer recess 53 is welded and sealed in place. Thus, the bellows assembly is formed and then pressurized to a selected pressure above ambient and sealed by welding ball 51 into recess 53. This internal pressurization causes the bellows 37 to expand longitudinally against its own resilient restoring force and thereby position the end cap 41 relative to the end cap 39 at a location that is representative of the net pressure differential acting upon the area of end cap 41.

In operation, the sealing engagement of the seal 25 against the seal seat 15 is controlled by the degree of expansion of the bellows 37 in response to the fluid pressure in outlet chamber 21 that acts upon the bellows 37. Therefore, in an extreme condition of high outlet pressure, the bellows is compressed to the limit of surfaces 43 and 45 coming together, and the central rod 27 is disengaged from the end cap 41, as shown in Figure 1. The pressure-enhanced and magnetically-enhanced sealing engagement between seal 25 and seal seat 15 is preserved, and no fluid flows through the regulator.

With reference now to Figure 2, there is shown a cross-sectional view of the regulator of Figure 1 operating in another extreme condition of substantially no fluid pressure in outlet chamber 21. Under this condition, the bellows 37 extends maximally until end cap 41 contacts the support 48 for the seal seat 15 and pushes the rod 27 and the attached piston 23 and seal 25 away from seal seat 15. Fluid under pressure is therefore free to flow from inlet port 11 through aperture 17 to the outlet port 13. The repulsion force by magnets 29 and 33 is overcome by the pressure force supplied by the bellows assembly, and the valve seal 15, 23 remains open for fluid flow therethrough until the pressure increases in outlet chamber 21. As the outlet pressure increases, the bellows compresses proportionately and, via rod 27, the piston 23 and seal 25 approaches the seal seat 15 under the static magnetic force provided by magnets 29 and 33. As the spacing between seal 25 and seat 15 decreases (due to increased pressure in outlet chamber 21), the flow of fluid therethrough decreases, thus decreasing the pressure in outlet chamber 21. Decreased pressure in outlet chamber 21 causes the bellows to expand and, via rod 27, increase the spacing between seal 25 and seat 15 to permit greater flow of fluid therethrough to increase the fluid pressure in chamber 21. In the limit, the bellows assembly expands to a seal and seat spacing which establishes a fluid pressure in outlet chamber 21 that approximately equals the internal pressure in bellows 37. Thus, the initial pressurization of the bellows 37 establishes the fixed limit of outlet fluid pressure around which the present invention regulates.

As shown in Figure 3, the regulator of Figure 1 is modified to include a fluid pressure connector 55 to the interior of the bellows assembly so that the regulating pressure limit of the assembly can be controlled in response to the pressure supplied to the interior of bellows 37.

In accordance with the present invention, the operating conditions of the regulator can be tailored to provide slight increase around the regulating value of outlet pressure in inverse proportion to the inlet or supply pressure, as illustrated in the graph of Figure 7. As shown in the diagram of Figure 6, this characteristic is desirable for monitoring the volume of gas remaining in a cylinder 81 of the gas under high pressure, simply by metering 83 the outlet pressure at much lower pressure levels. First, the internal gas volume of the bellows assembly in the regulators 82 of the present invention is maintained low by incorporating the solid volumes of end caps 39 and 41 within the inner volume of the bellows to effectively "stiffen" the resilience of the bellows to changing pressure conditions. Second, the diameter of the end cap 41 and, hence, the effective surface area of the bellows affects the amount of deviation about a stable value (in the form of droop or sag) in the curve of output gas pressure as a function of flow rate. Thus, the amount of such deviation decreases as the effective area of the bellows increases. Third, the cross-sectional area of the aperture 17 is selected to establish a small inverse variation 85 in the regulated value of outlet pressure 87 for variations in inlet pressure due, for example, to declining volume of gas in a supply cylinder 81. For a given pressure, increasing the aperture size increases the force required to overcome the pressure against the seal. The bellows (with pre-set charge) applies a constant force against a varying opening force, yielding the desired inverse deviation in outlet pressure. Thus, by selecting aperture diameter and bellows diameter suitably, a slight inverse variation 85 in outlet pressure of, say, 20 pounds per square inch gage pressure may appear in the nominal regulated value of outlet pressure as the supply pressure from a high-pressure gas cylinder 81 varies widely as it is emptied with use. Such slight variations 85 in outlet pressure over the wide range 91 of inlet pressures permit convenient low-pressure metering 83 to provide indication of the supply pressure and, hence, of remaining volume of gas in the supply cylinder 81. A secondary regulator 89 may be included in the system at a location downstream of the meter and ahead of a utilization system to reduce the variations 85 in the pressure of fluid supplied to the utilization system.

In each of the embodiments illustrated in Figures 1, 2 and 3 there is shown annular shield 70 and central anvil 72 which are concentrically disposed over the aperture 17, with the anvil 72 in contact with the central rod 27 to actuate the piston 23 and seal 25 through the aperture. The shield 70 includes a plural number of openings or vent holes 74 therethrough at spaced locations around the perimeter. This assembly in the structure of the present invention interrupts the lateral flow of fluid from aperture 17 and thereby reduces the Bernoulli effect upon the end cap 41. This assures smoother regulator operation by minimizing the conditions which tend to set up oscillations in the position of the end cap 41.

Referring now to Figure 4, there is shown a cross- sectional view of a pressure regulator that is oriented in coaxial configuration with its associated inlet and outlet connections. The body 61 of the regulator is generally cylindrical from the inlet port 63 to the outlet port 65, and encloses generally cylindrical inlet channel 67 and outlet channel 69 that are connected via central aperture 71. Standard high-pressure connectors may be welded to the body 61 at inlet and outlet ports to prevent leaks. A piston carrying a seal for engaging the aperture are disposed within the inlet channel 69, with a rod carried by the piston protruding through the aperture 71 into the outlet channel 69. The piston and seal are urged into engagement with the sealing surface that surrounds aperture 71 by the spring 75 which bears against the filter element 77 which, in turn, bears against, and seals against. a mating surface in a standard high-pressure cylinder valve. The filter element 77 is a generally cylindrical bellow shell of suitable sintered metal or ceramic material which is open at the input end and closed at the inner end. This filter 77 is arranged within the inlet port 63 to filter the fluid received from a supply. The filter 77 may thus be conveniently replaced each time a new supply cylinder is re-connected to the inlet port 63. The outlet channel 69 includes a bellows assembly 73 which is pre-charged to a level of fluid pressure about which the regulator is to operate, as previously described. Thus, as shown in Figure 4, the aperture 71 is open for fluid flow therethrough with the bellows assembly 73 expanded during conditions of low pressure within outlet channel 69. And, as shown in Figure 5, the aperture 71 is closed against fluid flow in response to the bellows assembly 73 being compressed under condition of high pressure within outlet channel 69. Between these extreme conditions, this illustrated embodiment of the regulator of the present invention operates as previously described in connection with the embodiment illustrated in Figures 1 and 2 to adjust the aperture opening in response to the fluid pressure in outlet channel 69. In this way, the outlet pressure is maintained at substantially the same pressure as is sealed within the bellows assembly 73, substantially independently of variations in supply pressure.

Claims

ClaimsWhat is claimed is :

1. Fluid pressure regulator apparatus comprising: a body having an aperture between inlet and outlet chambers for containing fluid flow therethrough; an element mounted within the inlet chamber for selective movement into and away from fluid-tight sealing engagement with the aperture; means disposed to rcsiliently urge said element into fluid-tight sealing engagement with said aperture; an actuator carried on said element to protrude through said aperture into the outlet chamber; and bellow means having longitudinally-expandable side walls disposed between ends thereof, said bellows means being disposed within the outlet chamber with an end thereof disposed to engage said actuator for positioning said actuator and said element relative to said aperture in response to pressure applied to the bellows means.

2. Fluid pressure regulator apparatus according to claim 1 wherein: said means disposed to resiliently urge said element includes a first permanent magnet carried by said element, and a second permanent magnet mounted with respect to the first permanent magnet in magnetic repulsion-orientation therewith for urging said element into sealing engagement with said aperture.

3. Fluid pressure regulator apparatus as in claim 1 wherein: said bellows means includes a fluid connector thereto for pressurizing the interior thereof to a selected pressure.

4. Fluid pressure regulator apparatus as in claim

1 wherein the end of said bellows means disposed to engage said actuator includes shield means surrounding the location at which said actuator is engaged, said shield means including descending wall portions positioned for interrupting the outwardly flowing stream of fluid from said aperture.

5. Fluid pressure regulator apparatus as in claim 1 wherein said bellow means includes stops means disposed internally of the side walls and sealed therein for limiting the inward travel of the ends thereof and to reduce substantially the internal volume between said side walls and ends.

6. Fluid pressure regulator apparatus as in claim 1 wherein: said inlet channel and said outlet chambers are substantially coaxially aligned with said aperture and said actuator and said element and said bellows means; said inlet chamber includes an internal recess; and filter means of generally elongated and hollow configuration is slidably disposed within said recess, and has an opening at the inlet and thereof communicating with the hollow interior, and has a closed end remote from the inlet end, said filter means having porous walls for permitting fluid to flow therethrough and inhibiting passage of particles therethrough.

7. The method of regulating the pressure of fluid flowing in a utilization system from a supply of fluid under pressure, the method comprising: constricting the fluid under pressure from the supply to the utilization system; including within the utilization system an expandable element pressurized to a selected fluid pressure; sensing the amount of expansion under fluid pressure in the utilization system relative to said selected value of fluid pressure; and altering said construction of fluid under pressure in relation to expansion of the element under the fluid pressure in the utilization system.

8. The method according to claim 7 including: the step of selectively pressurizing the expandable elements to a pressure level determined independently of supply fluid pressure and utilization system fluid pressure.

9. The method according to claim 7 wherein in the step of altering said construction the fluid pressure in the utilization system increases as the fluid supply pressure decreases, and comprising the step of monitoring only the utilization system fluid pressure to provide an indication of the supply fluid pressure.