WO2025240601A1

WO2025240601A1 - Electromagnetic pressure regulator for automated fluid pressure waveforms

Info

Publication number: WO2025240601A1
Application number: PCT/US2025/029339
Authority: WO
Inventors: Jeffrey Dean JENNINGS
Original assignee: Equilibar LLC
Current assignee: Equilibar LLC
Priority date: 2024-05-16
Filing date: 2025-05-14
Publication date: 2025-11-20
Anticipated expiration: 2026-11-16

Abstract

A back pressure regulator includes: a body including: a process surface including at least one inlet orifice and a plurality of outlet orifices; an inlet port communicating with an exterior of the body and with the at least one inlet orifice; an outlet port communicating with the exterior of the body and with the outlet orifices; a reference housing defining a reference cavity; a diaphragm secured between the body and the reference housing such that the diaphragm contacts the process surface, the diaphragm movable between a closed position and an open position; a transfer assembly disposed in the reference cavity, positioned against the reference side of the diaphragm; and an actuator configured to apply a force against the transfer assembly, in response to an electrical input.

Description

ELECTROMAGNETIC PRESSURE REGULATOR FOR AUTOMATED FLUID

PRESSURE WAVEFORMS

BACKGROUND OF THE INVENTION

[0001] The present invention relates to pressure regulators, and more particularly to pressure regulators using an electromagnetic actuator.

[0002] In various industrial applications, it is common to need to automate the pressure of a fluid to control a process pressure or to control a flow rate or other parameter. In other applications, it is needed to generate a pulsatile pressure waveform in a fluid.

[0003] The dome loaded back pressure regulator ("BPR") with multiple orifices, such as manufactured by Equilibar, LLC of Fletcher, North Carolina is highly suitable for generating precision pulsatile waveforms. This technology⁷ has been used in laboratory⁷ environments to generate a bypass fluid circulation in parallel with a pump to produce an exemplary pressure pulse waveform or to automate fluid pressure or flow rate.

[0004] Such direct diaphragm sealing BPRs use a " 1: 1" pilot pressure (typically air) on the dome, and use pneumatic electronic pressure regulators (EPR, or I/P's) to provide the pilot pressure. In such systems, the EPR contains a high speed proportional-integral-derivative (PID) control (or other similar control) loop which constantly adjusts its output air pressure to match that of an input signal. When the input setpoint signal to the EPR approximates that of a desired waveform, for example, then the air pressure and the resulting liquid pressure (controlled by the dome-loaded BPR) both provide exemplary approximations of the original signal waveform. A waveform should be understood as one of several examples of automated pressure control, and used in this document as such an example.

[0005] FIG. 1 illustrates a prior art back pressure regulator 1 of this type. The back pressure regulator 1 includes a body 2 including a process surface 6. A diaphragm 8 (also referred to interchangeably herein as a membrane) made of flexible material such as PTFE or fiber reinforced PTFE sheeting is disposed adjacent the process surface 6. The diaphragm 8 has opposed sides referred to as reference and process sides, with the process side facing the process surface 6. The perimeter of the diaphragm 8 is secured against the body 2 by a reference housing 10 which is attached to the body 2. Collectively, a space defined between the diaphragm 8 and the reference housing 10 is referred to as a "dome" 1'. A reference port 12 is formed in the reference housing 10 and is disposed in fluid communication with the reference side of the diaphragm 8. Inlet and outlet ports 14 and 16 respectively, are also formed in the body 2. At least one inlet orifice 18 is disposed in fluid communication with the inlet port 14 and the process surface 6. At least one outlet orifice 20 is disposed in fluid communication with the outlet port 16 and the process surface 6. The outlet orifices 20 are small holes or small openings.

[0006] While effective, such systems are bulky for mobile applications or other remote installations where an air supply or similar instrument gas supply is not available. Accordingly, there remains a need for a pressure control system that does not require a compressed air supply and also preferably does not require an electronic pressure regulator.

BRIEF SUMMARY OF THE INVENTION

[0001] This need is addressed by a BPR which utilizes electromagnetic force instead of a pressurized pilot pressure to provide the desired pressure.

[0002] Further, this device is designed to be capable of generating pressure waves in the range of 0-1 psig on the low end, but also up to 100 psig. In extreme applications, pressures up to 1000 psig can be generated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which:

[0004] FIG. 1 is a schematic cross-sectional view of a prior art pressure back pressure regulator; [0005] FIG. 2 is a schematic cross-sectional view of an exemplary' back pressure regulator;

[0006] FIG. 3 is a plan view of a process surface of the back pressure regulator of FIG. 2;

[0007] FIG. 4 is a schematic cross-sectional view of a portion of a back pressure regulator, illustrating a transfer member in combination with a platen of a stiffer material;

[0008] FIG. 5 is a schematic cross-sectional view of a portion of a back pressure regulator, illustrating a transfer member in combination with a platen of a stiffer material;

[0009] FIG. 6 is a schematic cross-sectional view of a portion of a back pressure regulator, illustrating an actuator directly coupled to a platen;

[0010] FIG. 7 is a block diagram of a back pressure regulator connected to a fluid system;

[0011] FIG. 8 is a block diagram of a back pressure regulator connected from a fluid system;

[0012] FIG. 9 is a schematic diagram of a commercially available solenoid;

[0013] FIG. 10 is a chart showing force vs. stroke data for a commercially available solenoid;

[0014] FIG. 11 is a chart showing force vs. power data for a commercially available solenoid;

[001 ] FIG. 12 is a chart showing force vs. voltage data for a commercially available solenoid;

[0016] FIG. 13 is a chart showing pressure vs. time data; and

[0017] FIG. 14 is a chart showing pressure vs. time data; [0018] FIG. 15 is a schematic cross-sectional view of a dome-loaded pressure back pressure regulator; and

[0019] FIG. 16 is a plan view of a process surface of the back pressure regulator of FIG. 15.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Generally, embodiments of the present invention improve upon the back pressure regulator shown in FIG. 1 by providing a practical method for transferring the pressure across the top of the diaphragm in a way that emulates the accurate pressure distribution of a fluid, yet is convenient and compact and does not present the complexities of a secondary transfer fluid. The BPR described herein works in a similar manner as the above described prior art BPR, except that instead of a true pilot fluid above the diaphragm, a force actuation system is used to compress a highly flexible force transfer object to push down on the diaphragm.

[0021] Now, referring to the drawings wherein identical reference numerals denote the same elements throughout the various views. FIG. 2 illustrates an exemplary back pressure regulator (BPR) 100 constructed according to one aspect of the present invention.

[0022] The back pressure regulator 100 includes a body 102, which may be cast, machined, or built-up from separate components. The material of the body 102 is selected to suit a particular application based on requirements such as temperature, pressure, chemical compatibility⁷, etc. Non-limiting examples of suitable materials which are chemical-resistant include 316 alloy stainless steel, brass, and high-strength polymers. The body 102 defines a process surface 104.

[0023] An inlet port 106 is formed in the body 102. At least one inlet orifice 108 is disposed in fluid communication with the inlet port 106 and the process surface 104. The function of the inlet orifice 108 is to bring the process fluid into the back pressure regulator 100.

[0024] An outlet port 110 is formed in the body 102. At least one outlet orifice 112 is disposed in fluid communication with the outlet port 110 and the process surface 104.

[0025] A diaphragm 114 is disposed adjacent the process surface 104. The diaphragm 114 may be constructed from a material which is chemically inert and/or chemically resistant. Non-limiting examples of such materials include PTFE, PEEK, polyimide, or fiber reinforced PTFE sheeting. The diaphragm may be one of many flexible and supple materials, such as a polymer with a hardness in the range of Shore D. Examples would be polyolefin or PTFE or similar polymers. In one example, the diaphragm thickness may be in a range of 0.003" to 0.010". In another example, such as for higher pressures, the diaphragm thickness may be in a range of with 0.004" to 0.020". Other suitable and process compatible materials, such as rubber, elastomers, and polymers may be used as long as they meet application requirements and are flexible in the range of pressures such that the diaphragm 114 responds to the application pressures and can lift as required.

[0026] When combined with a chemically inert and/or chemically resistant body material as described above, the back pressure regulator 100 is fully compatible for aggressive chemical contact. The diaphragm 114 has opposed sides referred to as reference and process sides, with the process side facing the process surface 104. The perimeter of the diaphragm 114 is secured against the body 102. In the illustrated example, the diaphragm 114 is secured to the body 102 by a relatively rigid reference housing 116 which is attached to the body 102, for example using bolts or other fasteners (not illustrated). Optionally, additional seals such as O-rings (not shown) may be provided between the diaphragm 114 and the body 102 and/or the diaphragm 114 and the reference housing 114 (note: a groove is shown for insertion of o-ring under the diaphragm). The reference housing 116 defines a reference cavity 118.

[0027] An actuator 120 is coupled to the reference housing 116. The purpose and function of the actuator 120 is to apply a controllable closing force to the diaphragm 114. Generally, any actuator which can receive electrical energy' as an input and produce a mechanical force as an output that can be modulated may be used. Generally, such actuators may operate on electrical and/or electromagnetic principles. One nonlimiting example of a suitable actuator is a solenoid. The solenoid includes an electromagnetic coil 122 (shown schematically) surrounding a ferromagnetic pushrod 124. When supplied with electrical current, the electromagnetic coil 122 attracts the pushrod 124, producing a force and displacement in the direction marked by the arrow "F" in FIG. 3. It is noted that while the interaction between the coil 122 and the pushrod 124 comprises the pushrod 124 or portions thereof being attracted to the coil 122, the coil 122 and pushrod 124 may be configured such that the pushrod 124 extends or "pushes" relative to a housing 126 of the actuator 120 when the coil is energized. Another suitable example of an actuator is a speaker voice coil (not illustrated). These work on principles similar to a solenoid, a difference being that the moving element of a voice coil is a permanent magnet.

[0028] A transfer assembly 130 is disposed between the actuator 120 and the diaphragm 114. The purpose and function of the transfer assembly 130 is to transfer the force applied by the actuator 120 to the diaphragm 114. A further purpose and function of the transfer assembly 130 is to spread out the force applied by the actuator 120 over an the surface area above the outlet orifices 112.

[0001] In an exemplary’ embodiment, the transfer assembly 130 comprises a rigid piston 132 attached to the pushrod 124 of the actuator 120 and a transfer member 134 positioned between the piston 132 and the diaphragm 114. The transfer member 134 is a highly flexible and very low hardness elastomeric material to provide much of the accurate pressure distribution of a fluid w hile also serving to conveniently transfer the force from a mechanical force generating system. An example transfer member may have a hardness less than Shore A20. In recent years, elastomers have become available with lower and lower Shore hardness, and presently materials less than Shore A20 have become common. A more preferred hardness is in the Shore ranges of O and OO and even OOO, such as the silicone elastomers used to simulate human skin in models. In one example, the hardness may be in the range of 10-50 Shore OOO. In another example, the hardness may be in the range of 10-50 Shore 00. An exemplary example of these ultra soft elastomers is ECOFLEX GEL silicone rubber gel with hardness in the range of Shore OOO 35. This product is available from smooth-on. Inc. of Macungie, Pennsylvania 18062 USA. [0002] The transfer member 134 is shaped to receive a force from the piston 132 driven by the actuator 120 generating a pressure in the elastomeric material due to its conformable nature. On the bottom of the transfer member 134. the transfer member 134 contacts the diaphragm 114 separating the controlled fluid from the upper pilot pressure. The highly conformable transfer member 134 is able to create a pressure field which is somewhat fluid-like in its distribution across the diaphragm 114.

[0003] In an alternate example, a sealed flexible container of fluid (not shown) could be substituted for the transfer member 134. Liquids such as ethanol or medical or food contact approved fluids (such as oils) may be used in applications where contamination in the event of a diaphragm failure is a concern.

[0004] The basic operating principle of the back pressure regulator 100 is similar to that of the prior art back pressure regulator 1 described above, with the diaphragm 114 being operable to vent fluid through the outlet orifices 112 when the process pressure exceeds the reference pressure applied by the actuator 120 and transfer assembly 130.

[0005] The inlet orifice(s) 108 may be located near the center of the diaphragm 114 and the multiple outlet orifices 112 may be arranged in a circular pattern or other similar closed shape outside of the inlet orifice(s) 108. Stated another way, the outlet orifices 112 may surround the inlet orifice(s) 108. The positioning of the outlet orifices 112 relative to the inlet orifices 108 is more significant for performance than the exact location of the inlet orifices 108 on the process surface 104. This geometry allows for a more symmetrical bending shape for the diaphragm 114, which supports improved precision by avoiding complex bending shapes that are difficult for the diaphragm 114 or the transfer member 134.

[0006] It is preferred that the inlet pressure be allowed to distribute through the inner portion of the diaphragm 114 (i.e., inboard of the outlet orifices 112) as much as possible, and not be blocked by the diaphragm 114 at the inlet orifice rim. This is because the precision of the device depends on the inlet pressure being applied to a larger area to persuade the diaphragm 114 to raise. [0007] Preferably, the BPR 100 is configured to distribute the inlet pressure evenly across and the inner area of the free diaphragm area ("FDA") to prevent the diaphragm from blocking the inlet orifices 108 directly. As used herein, the term free diaphragm area (FDA) refers to the portion of the diaphragm 114 that is free to deflect i.e. the portion that is inboard of the restraint provided by the reference housing 116. One example of such a pressure distribution system could be grooves or other patterns in the process surface 104 which allow the inlet fluid to move radially outward from the inlet orifices 108.

[0008] An example of a grooved pressure distribution system is shown in the example of FIGS. 2 and 3. wherein the radial array of shallow grooves 117 surround the inlet orifice(s) 108 and reach outward radially to aid in the fluid pressure being distributed closer to the outlet orifices 112. In the illustrated example, a generally cylindrical recess 119 is positioned at the process surface 104, joining the grooves 117 and the inlet orifice 108. The "inlet distribution area" compared to the FDA would be taken from the area of the circle transcribed by the groove pattern, divided by the circle defined by the Free Diaphragm diameter.

[0009] In another example of a pressure distribution system, the transfer member 134 may be shaped with a relief profile (relative to the process surface) such that the inlet pressure can more easily escape the inlet orifices 108 without being blocked, and moves freely outward towards the region of the outlet orifices 112. This profile could be provided by changes in the transfer member profile alone, or could be reinforced by a harder material inserted between the transfer member and the diaphragm local to the inlet orifice region (but not interfering with the delicate pressure/force interaction in the region local to the outlet orifices). FIG. 4 shows an example transfer assembly 230 including a piston 232, transfer member 234, and a platen 236. Any structure stiffer (more resistant to bending) than the diaphragm 114 may be used as a platen. Nonlimiting examples include polymers and metal alloys. A more detailed example of this example would be a polymeric disc, flat or curved concave to the inlet port, that is inserted or adhered to the upper side of the diaphragm 114 or even incorporated into the diaphragm 114, which acts to prevent the diaphragm 114 from blocking the inlet holes. Such an adaptation of the diaphragm system would define the pressure distribution area, wherein the area of the pressure distribution area is the effective area of the diaphragm modification which allows the inlet pressure to move outward.

[0010] In a very different embodiment of the diaphragm modification described above, the harder diaphragm modification would expand outward to overlap and at least one outlet orifice 112, thereby creating more of a structural platen to generate the valve action at the outlet orifices 1 12. As shown in FIG. 5, an example transfer assembly 330 includes a piston 332, transfer member 334, and a platen 336. Platen 336 overlaps the outlet orifices 112.

[0011] In an extension of this embodiment, the actuator 120 could apply force directly to the modified diaphragm system which incorporates a platen modification overlapping all outlet orifices 112, effectively eliminating the need for the flexible transfer member. As shown in FIG. 6, an example transfer assembly 430 includes a platen 436 connected directly to a pushrod 124 of the actuator 120. Platen 436 overlaps the outlet orifices 112.

[0012] In one example, the inlet pressure distribution area (the area in which one of the above methods of distributing the inlet pressure is present) is at least 30% of the FDA, and preferably at least 40%, and most preferably greater than 50%. In the example of FIG. 3, the pressure distribution area would be the area within a circle circumscribing the outer ends of the grooves 117 if present, or the area within the smallest circle enclosing the inlet orifices 108. In the example of FIGS. 4, 5, or 6, the pressure distribution area would be the surface area under the concave portion of the respective platen.

[0013] Any of the back pressure regulator configurations described above may be incorporated into a system with a pump in order to produce a desired pressure or pressure waveform in a process fluid.

[0014] One example application for such a pump/recirculation system 400 is shown in FIG. 7. The element labeled "application" 402 indicates a device or system requiring pulsatile flow where the fluid is supplied. In this figure, fluid flow connections are illustrated with single solid lines, and data or control connections are illustrated with single dashed lines.

[0015] The system 400 requires a pumping function with pressure and flow capacity greater than the maximum fluid flow required by the application. In the illustrated example, a non-positive displacement pump 404 such as a centrifugal pump is shown.

[0016] A tee 406 is present that allows the pumped fluid to proceed to the application 402, or to circulate through the BPR 100 and then back to a supply vessel 410, the pump inlet, or a drain (not shown).

[0017] An electronic controller 412 is coupled to the actuator of the BPR 100. The controller 412 is operable to supply variable electric power to the actuator in accordance with a desired pressure set point. Various types of devices may be used for this purpose, such as a programmable logic controller (PLC), a PID controller, or a microprocessor-based device.

[0018] In the illustrated example, a pressure transducer 414 is provided to sense the fluid pressure at the application 402 and transmit a signal representative thereof to the controller 412. This enables the controller 412 to implement closed-loop feedback control of the fluid pressure.

[0019] By changing the inlet pressure of the BPR 100, the application pressure is effectively controlled.

[0020] In one embodiment designed to produce a cyclical waveform, the controller 412 or 512 continually adjusts the electrical power to the actuator 120 and monitors the previous pressure waveforms and compares them against an ideal waveform, and continually adjusts the electrical power profile to create improved waveform fidelity. In summan', present inventive method of feedback may be based on an integrated assessment of whole cycle performance, whereas the prior art feedback was limited to controlling the pilot gas pressure pattern (via PID or equivalent adaptation).

[0021] FIG. 8 shows a system 500 with a back pressure regulator 100, application 502, drain 504, electronic controller 512, and pressure transducer 514. In this configuration, the BPR 100 with the controller 512 can be used to provide closed-loop back pressure control for an application.

[0022] The physics of the actuator 120, in particular electromagnetic solenoids, provide for this apparatus to provide an acceptable pulsatile waveform. Such force and actuation solenoids are commercially available. One example is a model T1130S available from Transmotec Inc. Burlington, Massachusetts 01803, USA shown schematically in FIG. 9 100.

[0023] Such simple devices provide force as a function of power input, but also as function of displacement (which affects the magnetic field as the magnet and coil are displaced, but also can be affected by an optional spring). Exemplary solenoid characteristics are show n in the graph of FIG. 10.

[0024] Because the BPR 100 is effectively a volume amplifier for the pilot pressure system, there is very little movement required for the actuator 120 (solenoid) as the diaphragm and 14 opens and closes the outlet orifices 112. In one example, the actuator axial movement is less than 0.12" and preferably less than 0.06". In another example, the actuator axial movement is less than 30% of the minimum inlet/outlet port diameter (where the highest fluid velocity is found in either the inlet port system or the outlet port system), preferably less than 20% of that ratio, (if the port throat is not circular, using the equivalent cross sectional area converted to an equivalent diameter geometrically). In another example, the actuator movement is less than that of the largest outlet orifice diameter. In another example, the displacement of the actuator 120 is less than 10% of the diameter of the electrical solenoid powering the movement, and a preferred example is less than 7% of said diameter.

[0025] Because the displacement of the solenoid is very small, the impact of linear displacement, and a relatively precise force versus power curve can be demonstrated from a simple commercial solenoid. The curves in FIGS. 11 and 12 were obtained by utilizing a low displacement value (approximately 0.06" compared to approximately 1" available travel) as described in the examples above. [0026] In one example of the BPR 100, the pressure controlled in the inlet is within 20% of the pressure derived from dividing the applied force from the solenoid by the FDA. In one example, the pressure agreement just stated is within 10%.

[0027] In the simplest control system example, the power to the actuator 120 is able to closely approximate the required pressure, and no automated feedback is required. A human can adapt the power settings and an adequate pressure control system would be obtained in the target pressure range.

[0028] In one example, a pressure sensor (e.g. transducer 414 or 514 of FIG. 7 or FIG. 8) is present to provide a feedback mechanism that allows the device to self adjust.

[0029] In one example of feedback (A) using a cyclical waveform, the control system adjusts its pressure within a single pressure waveform. Such an example would require fast feedback from the pressure system and adapting power in real time.

[0030] In another example of feedback (A), the control system adapts its pressure in real time based on the feedback from the process pressure sensor.

[0031] In another example (B) of a cyclical waveform, the control system analyzes the previous waveform(s) (through a pressure sensor) and makes adaptations as necessary to subsequent waveforms. Such adaptations could utilize or of several possible algorithms for averaging results and/or relaxing responses to prevent overshoot and providing stably guided waveforms. Such a system allows for precise pressure control at the application, even in the event that a long conduit is present or a significant elevation exists.

[0032] In a separate control embodiment (C), a pressure or force sensor is installed between the solenoid piston and the wetted diaphragm 114 to measure the pressure or force transmitted into the fluid. The pressure or force is proportional to the pressure controlled by the BPR 100. [0033] Approaches A and C, while not providing as precise local pressure control, offer the advantage of avoiding the expense of a process-wetted pressure sensor that would be required in many applications.

[0034] For testing purposes, a prototype of the BPR described above with a pressure sensor was integrated into a liquid system powered by a force actuator and platen compressing a bellows. This approximates the upper half of the full system described above. Referring to FIGS. 13 and 14, the plots represent voltage (vertical axis) plotted against time (horizontal axis). In each of these figures, t he upper waveform was the voltage applied to the solenoid. The lower waveform is the resulting pressure (psig) in the liquid bellows under piston.

[0035] FIG. 13 is the original square waveform of voltage input. FIG. 14 shows a square wave (upper waveform, dashed line), with a solid line in the upper waveform representing final "smoothed" voltage applied instead of the idealized square wave. This smooth waveform (running average smoothing), was instrumental in minimizing the inertial overshoot effects of the solenoid movement found in FIG. 13.

[0036] This subsystem demonstrates the ability to create an adaptive pulsation pressure pattern to a liquid from a force actuator. By applying a similar waveform to the inventive transfer elastomer, it is possible to similarly control and adapt the inlet fluid pressure to the BPR.

[0037] In the various control feedback loops described above, key parameters of the input waveform can be adjusted, such as min voltage, max voltage, timing, and the degree of edge smoothing via one of several algorithms (such as running average smoothing). More sophisticated waveforms can easily be adapted such as sinusoidal or other waveform features.

[0038] No examples in this application should be interpreted as limiting the scope of the inventive features to lower pressures or pulsatile flow only. Each of the inventive examples and embodiments may be combined to meet the requirements of applications. [0039] A more powerful solenoid could be used to achieve pressures up to 10 psig, or up to 150 psig, or as required according to the specified formula (pressure = force divided by piston area) example above. (JJ Note: we decided not to mention that the FDA and Piston Area could be similar as depicted, or could be different. Regardless, the pressure will be determined using the piston area).

[0040] Similarly, while this application described pulsatile applications, modification of the pressure control system could be used to adapt to more constant applications of pressure control and even flow control, whereby the power to the solenoid and thereby the fluid pressure controlled is responding to the feedback of a PID controller monitoring a flow meter or other process variable (such as pH or temperature).

[0041] The apparatus and method described herein has advantages over the prior art. The system should be simpler and not require a pressurized fluid such as compressed air and should not require a separate EPR.

[0042] At least some of the features described herein are advantageous for incorporation into a back pressure regulator which is dome-loaded (i.e. has its reference pressure set by a pressurized gas). An example is shown in FIGS. 15 and 16. A back pressure regulator 600 is similar in overall construction to the back pressure regulator 100 described above. Elements of the back pressure regulator 600 not explicitly described may be considered to be identical to corresponding elements of the regulator 100.

[0029] The back pressure regulator 600 includes a body 602 that defines a process surface 604.

[0030] An inlet port 606 is formed in the body 602. At least one inlet orifice 608 is disposed in fluid communication with the inlet port 606 and the process surface 604.

[0031] An outlet port 610 is formed in the body 602. At least one outlet orifice 612 is disposed in fluid communication with the outlet port 610 and the process surface 604. [0032] A diaphragm 614 is disposed adjacent the process surface 604. The diaphragm 614 has opposed sides referred to as reference and process sides, with the process side facing the process surface 604. The perimeter of the diaphragm 614 is secured against the body 102. In the illustrated example, the diaphragm 614 is secured to the body 602 by a relatively rigid reference housing 616 which is attached to the body 602, for example using bolts or other fasteners (not illustrated). Optionally, additional seals such as O-rings (not shown) may be provided between the diaphragm 614 and the body 602 and/or the diaphragm 614 and the reference housing 616. The reference housing 616 defines a reference cavity’ 618 on the surface facing the diaphragm 614.

[0033] Collectively, a space defined between the diaphragm 614 and the reference cavity' 618 is referred to as a "dome" 618'. A reference port 621 is formed in the reference housing 616 and is disposed in fluid communication with the reference side of the diaphragm 614.

[0034] The basic operating principle of the back pressure regulator 600 is similar to that of the prior art back pressure regulator 1 described above, with the diaphragm 614 being operable to vent fluid through the outlet orifices 612 when the process pressure exceeds the reference pressure. In this type of BPR, the reference pressure would be supplied as pressurized gas entering through the reference port 621. For example, this may be supplied by a pilot pressure regulator (not shown).

[0035] The inlet orifice(s) 608 may be located near the center of the diaphragm 614 and the multiple outlet orifices 612 may be arranged in a circular pattern or other similar closed shape outside of the inlet orifice(s) 608. Stated another way, the outlet orifices 612 may surround the inlet orifice(s) 608. This geometry allows for a more symmetrical bending shape for the diaphragm 614, which supports improved precision by avoiding complex bending shapes that are difficult for the diaphragm 614.

[0036] It is preferred that the inlet pressure be allowed to distribute through the inner portion of the diaphragm 614 (i.e., inboard of the outlet orifices 612) as much as possible, and not be blocked by the diaphragm 614 at the inlet orifice rim. This is because the precision of the device depends on the inlet pressure being applied to a larger area to persuade the diaphragm 614 to raise.

[0037] Preferably, the BPR 600 is configured to distribute the inlet pressure evenly across and the inner area of the free diaphragm area ("FDA") to prevent the diaphragm from blocking the inlet orifices 608 directly. One example of such a pressure distribution system could be grooves or other patterns in the process surface 604 which allow the inlet fluid to move radially outward from the inlet orifices 608. "Radial grooves" could be perfectly radial as depicted, or could be effectively radial by providing multiple grooves that branch from a common center area outward to an outer radius.

[0043] An example of a grooved pressure distribution system is shown in the example of FIGS. 15 and 16, wherein the radial array of shallow grooves 617 surround the inlet orifice(s) 608 and reach outward radially to aid in the fluid pressure being distributed closer to the outlet orifices 612. In the illustrated example, a generally cylindrical recess 619 is positioned at the process surface 604, joining the grooves 617 and the inlet orifice 608. The "inlet distribution area" compared to the FDA would be taken from the area of the circle transcribed by the groove pattern, divided by the circle defined by the Free Diaphragm diameter.

[0044] The foregoing has described a back pressure regulator and a method for its use. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0045] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. [0046] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

WHAT IS CLAIMED IS:

1. A back pressure regulator, comprising: a body including: a process surface including at least one inlet orifice and at a plurality⁷ of outlet orifices, wherein the outlet orifices are separate from the at least one inlet orifice; an inlet port communicating with an exterior of the body and with the at least one inlet orifice; an outlet port communicating with the exterior of the body and with the outlet orifices; a reference housing defining a reference cavity; a diaphragm having opposed reference and process sides secured between the body and the reference housing such that the process side contacts the process surface, the diaphragm movable between a closed position blocking fluid flow from the at least one inlet orifice to the outlet orifices, and an open position permitting fluid flow from the at least one inlet orifice to the outlet orifices; a transfer assembly disposed in the reference cavity, positioned against the reference side of the diaphragm; and an actuator configured to apply a force against the transfer assembly, in response to an electrical input.

2. The back pressure regulator of claim 1, wherein the transfer assembly includes a soft, flexible transfer member.

3. The back pressure regulator of claim 2, wherein the transfer member is a silicone gel having a hardness of Shore A or less.

4. The back pressure regulator of claim 1, wherein the transfer assembly includes a rigid piston between the actuator and the transfer member.

5. The back pressure regulator of claim 2, further including a concave platen stiffer than the transfer member, positioned between the transfer member and the diaphragm.

6. The back pressure regulator of claim 5, wherein the concave platen overlaps the outlet orifices.

7. The back pressure regulator of claim 1, wherein the transfer assembly includes a rigid platen coupled to the actuator.

8. The back pressure regulator of claim 7, wherein the platen overlaps the outlet orifices.

9. The back pressure regulator of claim 1. wherein the at least one inlet orifice is located near a center of the diaphragm and is surrounded by the outlet orifices.

10. The back pressure regulator of claim 9. wherein the at least one inlet orifice communicates with a radial array of open grooves in the process surface.

11. The back pressure regulator of claim 1, wherein a pressure distribution area enclosed by the at least one inlet orifice comprises at least 30% of a free diaphragm area of the diaphragm.

12. The back pressure regulator of claim 1, wherein the actuator is a solenoid.

13. The back pressure regulator of claim 1, in combination with a pump upstream of the back pressure regulator, an application downstream of the back pressure regulator, an electronic controller configured to provide a setpoint to the back pressure regulator, and a pressure transducer configured to provide a signal to the controller.

14. A back pressure regulator, comprising: a body including: a process surface including at least one inlet orifice and at least one outlet orifice, wherein the at least one outlet orifice is separate from the at least one inlet orifice; an inlet port communicating with an exterior of the body and w ith the at least one inlet orifice; an outlet port communicating with the exterior of the body and with the at least one outlet orifice; a reference housing defining a reference cavity and are reference port communicating with an exterior of the reference housing and the reference cavity; a diaphragm having opposed reference and process sides secured between the body and the reference housing such that the process side contacts the process surface, and a dome is defined between the reference cavity' and the reference side of the diaphragm, the diaphragm being movable between a closed position blocking fluid flow from the at least one inlet orifice to the at least one outlet orifice, and an open position permitting fluid flow' from the at least one inlet orifice to the at least one outlet orifice; and wherein the at least one inlet orifice communicates with a radial array of open grooves in the process surface.