Floating and damping pressure independent control valve (f&d PICV)

Abstract

A pressure independent control valve (PICV) for hydronic and HVAC systems includes two opposing control valves mounted on a common spindle, a differential pressure regulating assembly comprising either dual opposing valves or a cylindrical valve, a diaphragm biased by a return spring, and a hydraulic damper utilizing system fluid through a clearance gap. The valve features a co- axial inline configuration of inlet, outlet, and internal regulating elements, enabling frictionless, balanced operation. Sealing components are disengaged during flow regulation and only activated at shutoff, allowing high-precision modulation without hysteresis or oscillations. A manual adjustment mechanism enables simultaneous fine and coarse flow setting via both control valves. The architecture supports high differential pressures, reduced actuator torque, and improved longevity. The valve design is suitable for stainless steel production using investment casting methods, supporting compact, energy-efficient operation across a wide flow range with stable performance.

Description

[0001] FLOATING AND DAMPING PRESSURE INDEPENDENT CONTROL VALVE (FD PICV)

[0002] Applicant: Omar, Osama Ahmed Mohamed Mohamed

[0003] Inventors:

[0004] 1. Abdelkhalek, Ahmed Mohamed Mohamed Omer

[0005] 2. Omar, Osama Ahmed Mohamed Mohamed

[0006] Priority Claim: US 63 / 647,904, filed May 15, 2024

[0007] Correspondence Address:

[0008] +20 11 23798869 +971504353033

[0009] TECHNICAL FIELD

[0010] The present invention relates to pressure-independent control valves (PICVs) for hydronic and heating, ventilation, and air conditioning (HVAC) systems. More specifically, it provides a Floating and Damping PICV (F&D PICV) that achieves frictionless flow regulation without osscillations.

[0011] BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings illustrate embodiments of the invention. Like reference numerals are used to identify similar components across figures.

[0013] • FIG. 1 is a perspective view of the Floating and Damping Pressure Independent Control Valve (F&D PICV) with the actuator (100) mounted, showing the external housing and complete operational assembly.

[0014] • FIG. 2 is a perspective view of the F&D PICV without the actuator, illustrating the manual adjustment mechanism and the upper valve body configuration.

[0015] • FIG. 3 is a longitudinal sectional view of the internal structure of the F&D PICV in the embodiment utilizing dual differential pressure valves (20, 22), illustrating the diaphragm (50), spring (70), and control valves (10, 12).

[0016] • FIG. 4 is a longitudinal sectional view of the embodiment incorporating the single differential cylindrical valve (30), showing its integration with the diaphragm and control valves (10, 12).

[0017] • FIG. 5 is a sectional isometric view of the embodiment of FIG. 4 with both the differential cylindrical valve (30) and the control valves (10, 12) in the fully open position, including an enlarged detail of the cylindrical valve components.

[0018] • FIG. 6 is a sectional isometric view similar to FIG. 5, but with the differential cylindrical valve (30) shown in the fully closed position, highlighting the innovative sealing mechanism involving inclined surfaces (35, 36) and 0-ring depressions (37).

[0019] • FIG. 7 is a schematic pressure distribution diagram illustrating the three pressure zones in the F&D PICV— P1 (230), P2 (220), and P3 (210)— demonstrating balanced pressure across the diaphragm enabled by the co-axial architecture.

[0020] • FIG. 8 is a sectional view similar to FIG. 4, showing both control valves (10, 12) in the fully closed position, indicating the sealing engagement on both seats.

[0021] • FIG. 9 is a performance graph of the F&D PICV, plotting flow rate versus differential pressure (DP), showing stable regulation up to and exceeding 12 bar.

[0022] • FIG. 10 is a velocity-time graph illustrating the damping effect on the diaphragm (50) and differential valves (20, 22 or 30), showing rapid settling of movement compared to conventional PICVs.

[0023] • FIG. 11 is a time-position graph of the diaphragm (50) for the F&D PICV, showing smooth convergence to equilibrium without oscillatory overshoot due to the integrated hydraulic damper (40).

[0024] • FIG. 12 is a comparative velocity-time graph for a conventional PICV, illustrating sustained oscillations and vibrations due to the absence of damping. • FIG. 13 is a schematic system layout showing the integration of the F&D PICV into a Fan Coil Unit connection module (FCU-Link), demonstrating its use in hydronic HVAC systems.

[0025] DESCRIPTION

[0026] The present invention provides a Floating and Damping Pressure Independent Control Valve (F&D PICV) that achieves breakthrough performance through:

[0027] 1. Frictionless Pressure Force Cancellation

[0028] Two opposed strategically selected unequal-diameter control valves (10, 12) mounted on a common spindle (60)

[0029] Cancel equivalent pressure forces on the spindle with zero net friction

[0030] Generate gentle return opening force for springless auto-return

[0031] Unlike existing PICVs which has a max Differential Pressure beyond which the PICV collapse to handle and control the flow rates, this invention arrangement makes this the First PICV to handle any water Differential Pressure (tested to 174 psi / 1200 kPa) as pressure forces vanish proportionally as pressure increases, while keeping a minor force for springless auto-return

[0032] Control valves feature different seat diameters and innovative plug-to-seat spacing and profile, for frictionless shutoff and improved control curves.

[0033] Unlike conventional PICVs that rely on single-valve designs with spring returns (Danfoss U.S. 8,544,485), the F&D PICV eliminates friction and spring dependencies through opposed unequal-diameter valves (10,12) that autobalance hydraulic forces.

[0034] 2. Frictionless Differential Pressure Control Valve

[0035] The present invention introduces two alternative configurations for achieving precise, stable differential pressure regulation without introducing internal friction. Both designs aim to maintain an accurate force balance between a diaphragm and return spring, eliminating the destabilizing effects of conventional sealing and mechanical resistance.

[0036] 2.1 Opposing Differential Valve Configuration

[0037] The differential pressure regulating mechanism of the present invention comprises a pair of opposing differential pressure valves (20, 22), as illustrated in Figure 1, operate in conjunction with a spring-loaded diaphragm (50) and one or more biasing springs (70) to maintain a stable pressure differential across the two control valves (10, 12).

[0038] In contrast to conventional PICVs, which typically utilize a single differential valve, the present invention introduces a novel configuration wherein two differential pressure valves are arranged in direct opposition, acting against one another along a common axis. These valves are designed with identical diaphragm diameters, and when exposed to the same pressure differential (DP), the resulting net hydraulic force becomes zero. This inherently balanced configuration eliminates undesired motion or side loading on the diaphragm and associated components.

[0039] Moreover, although the diaphragm diameters are the same, the valves feature differently sized flow-through areas, enabling one valve (with the larger throat area) to close first to control bulk fluid flow, while the second valve (with the smaller area) remains open for fine-tuning and precise modulation. This sequential closure behaviour forms a two-stage regulation mechanism capable of accurately controlling both high and low flow rates with minimal pressure loss.

[0040] Crucially, this configuration does not employ any O ring seals or preloaded sealing elements on the differential valves. As a result, no frictional sealing forces are present, and the resultant mechanical force on the diaphragm system is effectively zero. This enables a truly floating, frictionless pressure regulating mechanism operated purely by spring and diaphragm interaction.

[0041] This arrangement represents a true spring-loaded, diaphragm-operated differential pressure valve architecture, offering high sensitivity, accurate flow control, and stable modulation behaviour without the drawbacks of hysteresis, oscillation, or drift commonly observed in traditional PICV designs.

[0042] 2.2 Single Differential Cylindrical Valve Configuration

[0043] In an alternative embodiment of the invention, the differential pressure regulation is achieved using a single differential cylindrical valve (30), as shown in Figure 2 and detailed in Figure 4. This configuration replaces the dual opposing differential valves (20, 22) with a compact cylindrical assembly designed to maintain a stable pressure differential across the control valves (10, 12).

[0044] In conventional PICV designs, cylindrical pressure regulators typically rely on preloaded sealants or O ring-based sealing systems to ensure tight shutoff. These sealing elements introduce significant frictional forces, which act on the moving components of the valve and directly affect the force balance between the diaphragm and the return spring. Such friction forces are not only dependent on operating pressure, but they also reverse direction depending on the motion of the valve element, making the system inherently unbalanced and reducing accuracy and responsiveness.

[0045] The present invention addresses this issue by introducing, for the first time, a frictionless sealing configuration within the cylindrical valve design. The differential cylindrical valve (30) comprises a stationary inner cylinder with O ring seals (32, 33), and a movable outer cylinder (31) that contains a specialized internal geometry.

[0046] This geometry includes two inclined surfaces (35, 36) and a central depression (37) along the inner surface of the moving cylinder. During normal operation (i.e., when the valve is regulating flow and not at shutoff), the 0 rings are positioned within the depression (37), remaining uncompressed and disengaged from sealing contact. This design ensures that no frictional force is exerted on the moving parts, allowing the diaphragm and spring mechanism to operate in true force equilibrium.

[0047] As the valve approaches its shutoff position, the inclined surfaces (35, 36) engage with the 0-rings, gradually compressing them to create a tight, leak-free seal. Because sealing only occurs at the final stage of travel, and not during modulation, friction is eliminated throughout the operating range, and sealing is achieved without compromising responsiveness, accuracy, or stability.

[0048] This novel configuration enables the differential cylindrical valve to function as a fully floating, frictionless pressure regulating mechanism, ideal for applications requiring precise modulation, long service life, and resistance to hysteresis and oscillation.

[0049] 3. Co-Axial Inline Configuration

[0050] The present invention introduces a co-axial inline structural arrangement wherein the inlet port (91), outlet port (92), diaphragm chamber (50), and biasing springs (70) are all aligned along a single longitudinal axis. This unified alignment differs significantly from conventional PICVs, which often employ staggered or offset geometries.

[0051] The co-axial configuration provides multiple performance advantages. Most notably, it reduces internal turbulence by allowing the fluid to pass through the valve body in a straight, unobstructed path, minimizing flow redirection and associated energy losses. The streamlined geometry enables a smaller, more compact valve body, which is both lighter in weight and more efficient in manufacturing and installation.

[0052] From a hydraulic standpoint, this arrangement maximizes the utilization of the annular flow area within the valve body. By enabling symmetrical and balanced flow distribution around the central axis, the design supports a laminar, consistent flow profile even at varying flow rates. This eliminates the formation of eddies, vortices, and recirculation zones, which are common in asymmetrical or angular flow paths and are a primary source of pressure drop, flow instability, and operational noise in traditional designs.

[0053] In addition to its hydraulic benefits, the co-axial configuration eliminates the need for a sealed chamber above the diaphragm, which is commonly found in conventional PICVs. In traditional designs, pressure is transmitted to the diaphragm via small internal holes or capillary tubes, forming a closed chamber that can trap air pockets and chemical residues. These trapped air volumes - being compressible and sensitive to temperature fluctuation - introduce dynamic inaccuracies in pressure sensing and response. This compromises the force balance between the diaphragm and the return spring, leading to erratic valve modulation.

[0054] Furthermore, during initial operation or maintenance cycles, cleaning chemicals, impurities, or system debris (sludge) may become trapped in this closed chamber above the diaphragm. Since conventional chambers are often inaccessible and non-vented, such contamination accelerates diaphragm degradation and wear, significantly reducing valve service life.

[0055] By integrating the diaphragm directly into the main water flow path - without intermediate chambers or pressure transfer bores - the present invention ensures that pressure sensing is instantaneous, accurate, and self-cleaning. This design not only improves regulation accuracy and response time, but also enhances operational hygiene and diaphragm longevity.

[0056] 4. Integrated Hydraulic Damper

[0057] The present invention incorporates a novel hydraulic damping mechanism (40) designed to suppress internal oscillations and stabilize the differential pressure regulation system. The damper consists of a piston (41) and a housing cylinder (95) arranged coaxially, forming a closed chamber that utilizes the system’s own fluid as the damping medium.

[0058] Unlike conventional damping systems that rely on sealing elements, bypass lines, or external hydraulic circuits, this damper employs a precisely engineered clearance gap between the piston and the inner surface of the housing cylinder. This gap acts as a built-in laminar flow orifice, allowing fluid to pass through at a rate proportional to the velocity of piston movement, thereby generating a velocity-dependent damping force.

[0059] Critically, this damper design is frictionless - it contains no dynamic seals and introduces no static resistance to movement. As a result, it exerts no force on the valve mechanism when stationary or in slow equilibrium movement, preserving the natural force balance between the diaphragm and spring components. Damping only occurs during dynamic motion, effectively eliminating overshoot, vibration, and instability during pressure transients.

[0060] This floating, seal-less damper enables the PICV to operate at higher pressure differentials than conventional designs, without introducing control error or wear. By suppressing unwanted oscillations, it significantly improves regulation accuracy, system reliability, and actuator lifespan, while also reducing operational noise and valve fatigue.

[0061] 5. Manual Flow Adjustment Mechanism

[0062] The F&D PICV may include a manual adjustment mechanism (110) that is operatively coupled to the spindle (60) controlling both the first (10) and second (12) control valves. This adjustment mechanism enables the user to set a precise design flow rate by simultaneously adjusting the positions of both control valves - one optimized for coarse flow regulation and the other for fine tuning. This dual-seat configuration allows for more accurate flow setting than conventional single-seat PICVs, particularly over wide modulation ranges or low flow conditions.

[0063] During operation, the manual adjustment may be used:

[0064] - as a standalone flow-setting mechanism in systems without actuators, or - in combination with an actuator (100), where the manual adjustment defines the maximum allowable flow rate, and the actuator dynamically regulates flow based on temperature control requirements.

[0065] This represents the first implementation of a manual setting mechanism applied to a dual-seat PICV architecture, significantly enhancing adjustment resolution and operational flexibility.

[0066] 6. MANUFACTURABILITY AND MATERIAL COMPATIBILITY

[0067] The co-axial, streamlined configuration of the present PICV, combined with its reduced part count, absence of internal springs and seals in critical moving components, and uniform cross-sectional geometry, makes it uniquely suited for advanced manufacturing methods. Unlike conventional small-sized PICVs, which are typically machined from brass or DZR due to their geometrical constraints, the invention enables for the first time the production of such valves using lost wax casting, investment casting, or crystal water wax casting in stainless steel (SS). This opens the way for producing durable, corrosion-resistant PICVs in stainless steel (specially at smaller sizes) and lower cost, a process that was previously impractical or uneconomical due to machining limitations.

Claims

INDUSTRIAL APPLICABILITYThe F&D PICV achieves transformative performance across multiple sectors through its frictionless, high-DP design:1 . HVAC Systems• Chilled Water Plants• District Energy Networks2. Economic Benefits• Energy Savings• Maintenance Reduction3. Integration CapabilitiesDirect compatibility with:• BACnet MS / TP and Modbus RTU protocols• Digital twins via embedded sensors (optional)• Pressure-independent thermal storage chargingCLAIMS1 . A floating and damping pressure independent control valve (F&D PICV) for regulating fluid flow in a hydronic or HVAC system, comprising:• a valve body (90) having an inlet port (91) and an outlet port (92), arranged along a common longitudinal axis;• two control valves (10, 12) disposed in opposition and mounted on a common spindle (60), each configured to regulate a portion of the fluid flow in opposite directions, such that pressure forces acting on the spindle are balanced;• a differential pressure regulating assembly operatively coupled to the control valves, comprising:• either two opposing differential pressure valves (20, 22), or• a single differential cylindrical valve (30) comprising a moving cylinder (31) and a stationary inner cylinder, wherein O-ring seals (32, 33) are positioned within a depression (37) in the moving cylinder and remain uncompressed during flow regulation;• a diaphragm (50) coupled to at least one return spring (70), the diaphragm being exposed directly to fluid pressure from the inlet and outlet without an enclosed chamber or pressure-transmitting bore;• a damper (40) comprising a piston (41) and a housing cylinder (95), the damper configured to use system fluid and a clearance gap as a velocitydependent orifice without dynamic seals or bypass lines, wherein the arrangement is configured to:• provide frictionless operation of the differential pressure regulating mechanism;• achieve automatic pressure force equilibrium across the diaphragm and spring system;• eliminate oscillations, hysteresis, cavitation, and noise; and• enable compact inline co-axial geometry for low energy consumption and high control accuracy.

2. The PICV of claim 1 , wherein the two control valves (10, 12) have different flow-through areas and seat diameters, such that one valve provides coarse flow control and the other provides fine flow modulation, enabling sequential closing and enhanced flow accuracy.

3. The PICV of claim 1 or 2, wherein the differential pressure regulating assembly comprises a pair of opposing differential pressure valves (20, 22) having identical disk diameters but different orifice areas, configured such that the net hydraulic force on the diaphragm is neutralized duringmodulation, thereby eliminating internal friction and enabling precise, balanced pressure control.

4. The PICV of any of claims 1 to 3, wherein the differential pressure regulating assembly comprises a single differential cylindrical valve (30) having a moving cylinder (31) with at least one depression (37) and at least one inclined sealing surface (35, 36), configured such that 0-ring seals (32, 33) remain uncompressed during normal flow regulation and are only engaged at the shutoff position to form a fluid-tight seal without generating friction during modulation.

5. The PICV of any of claims 1 to 4, wherein the damper (40) comprises a piston (41) disposed within a housing cylinder (95), and a clearance gap formed between the piston and the inner surface of the housing, the clearance gap acting as a velocity-dependent orifice that provides dynamic damping using the system fluid, without requiring seals, bypass channels, or additional damping fluid.

6. The PICV of any of claims 1 to 5, wherein the diaphragm (50) is arranged directly within the main flow path between the inlet (91) and outlet (92), without the use of a closed chamber or pressure-transmitting bore, thereby preventing air entrapment above the diaphragm and ensuring accurate pressure response uninfluenced by compressible gases or chemical residues.

7. The PICV of any of claims 1 to 6, wherein the inlet port (91), outlet port (92), diaphragm (50), return spring assembly (70, 71), damper (40), differential pressure regulating valves (20, 22) and / or cylindrical valve (30), and control valves (10, 12) are arranged along a common longitudinal axis, forming a co-axial inline configuration that reduces turbulence, minimizes pressure drop, and enables a compact, lightweight valve structure with improved hydraulic performance and structural balance.

8. The PICV of any of claims 1 to 7, wherein the opposing control valves (10, 12) are configured such that, upon removal or deactivation of the actuator (100), the pressure imbalance resulting from their differing seat diameters generates a gentle restoring force that returns the valve to an open position without requiring a mechanical return spring.

9. The PICV of any of claims 1 to 8, wherein the control valves (10, 12) are mounted on a common spindle (60) with adjustable spacing between the valve plugs, such that the distance between the plugs is greater than the distance between the valve seats, enabling sequential sealing during closure and ensuring tight shutoff without the need for micrometer-level alignment.

10. The PICV of any of claims 1 to 9, wherein the sequential closure of the control valves (10, 12) resulting from the offset spacing between the plugs and seats provides non-linear flow characteristics, enabling precisemodulation performance such as equal percentage flow control without reducing the valve throat area.11 . The PICV of any of claims 1 to 10, wherein the frictionless, floating configuration of the internal components enables stable and accurate operation at differential pressures up to and exceeding 12 bar, with no inherent upper limit on controllable differential pressure within the structural and material limits of the valve.

12. The PICV of any of claims 1 to 11 , wherein the damper (40) is configured to act on oscillatory movement of the diaphragm (50) or differential valve (20, 22, or 30), providing velocity-dependent damping force only during dynamic transitions, thereby suppressing pressure-induced vibrations and enabling the valve to reach equilibrium without overshoot or instability.

13. The PICV of any of claims 1 to 12, wherein the damper (40) is fully integrated within the valve body (90) and uses the system fluid as the damping medium, eliminating the need for external hydraulic circuits, separate fluid chambers, or mechanical adjustment components.

14. The PICV of any of claims 1 to 13, wherein the system is configured to suppress internal flow oscillations and absorb inlet pressure fluctuations, such that the outlet flow remains steady even when subjected to dynamic upstream pressure variations.

15. The PICV of any of claims 1 to 14, wherein the integrated damper (40) contributes to the elimination of cavitation, water hammer, and acoustic noise by damping rapid pressure changes and preventing high-frequency oscillatory motion of internal valve components.

16. The PICV of any of claims 1 to 15, wherein the co-axial arrangement of components and the elimination of internal friction enable homogeneous flow distribution across the valve cross-section, resulting in reduced turbulence, improved flow uniformity, and enhanced thermal exchange performance in downstream equipment such as fan coil units or heat exchangers.

17. The PICV of any of claims 1 to 16, wherein the absence of a sealed chamber above the diaphragm (50) eliminates the risk of air entrapment, ensuring accurate pressure sensing and preventing performance degradation due to compressible fluid behavior or chemical contamination.

18. The PICV of any of claims 1 to 17, wherein all internal movable elements, including the control valves (10, 12), differential regulating components (20, 22, or 30), diaphragm (50), and damper (40), operate without mechanical contact or sliding seals, thereby minimizing wear, extending operational life, and reducing maintenance requirements.

19. The PICV of any of claims 1 to 18, wherein the valve actuator (100) operates under significantly reduced torque due to the pressure-balanced,frictionless configuration, enabling the use of smaller, lower-power actuators and improving energy efficiency across the control system.

20. The PICV of any of claims 1 to 19, wherein the valve is integrated into a fan coil unit connection assembly (FCU-Link), providing combined functions of pressure-independent flow control, shut-off, flushing, and strainer cleaning within a single compact unit.21 . The PICV of any of claims 1 to 20, wherein the valve assembly is configured for factory integration and pressure testing as part of a modular connection unit for HVAC systems, reducing installation time, minimizing field errors, and ensuring pre-validated hydraulic performance.

22. The PICV of any of claims 1 to 21 , wherein the modular valve unit is adapted for use in fan coil units (FCUs), air handling units (AHUs), or terminal units in hydronic HVAC systems, providing scalable compatibility across different flow capacities and system pressures.

23. The PICV of any of claims 1 to 22, wherein the valve is manufactured in multiple nominal sizes including DN15, DN20, DN25, DN32, DN40, DN50, DN65, DN100, DN150, and even larger sizes, each configured to provide pressure-independent flow regulation over a defined operating range, with no inherent upper limit on maximum controllable differential pressure.

24. The PICV of any of claims 1 to 23, wherein the design allows for 100% leak-free shutoff by means of sequential plug seating with elastomeric or spring-loaded sealing elements, eliminating the need for precisely fixed plug-to-seat distances and ensuring reliable closure even under manufacturing tolerances or thermal expansion.

25. The PICV of any of claims 1 to 24, wherein the differential cylindrical valve (30) includes at least two inclined surfaces (35, 36) that engage the O-ring seals (32, 33) only at the end of the valve stroke, thereby achieving a progressive sealing action that minimizes shock loads and prevents abrupt flow cut-off.

26. The PICV of any of claims 1 to 25, wherein the valve components are configured for manufacturing using precision casting, CNC machining, or additive manufacturing, enabling consistent alignment of the co-axial geometry and tight tolerances required for floating, frictionless operation.

27. A method of manufacturing a pressure independent control valve (PICV) of the type defined in any of claims 1 to 26, comprising:• producing the valve body (90), internal guide structures, and coaxially aligned chambers as a single-piece component using lost wax casting, investment casting, or crystal water wax casting in stainless steel (SS);• wherein the co-axial, floating, and seal-free configuration of the PICV enables precision casting with uniform wall thickness and minimal postprocessing,

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