Flow control valve with roll-over septum

Abstract

A flow control valve including a main valve and a pilot valve for controlling a piston of the main valve. The valve can be controlled by a control system based on pressure or temperature measurements in a system supplied or controlled by the valve. The valve can operate as a pressure independent control valve, utilizing pressure measurements from a supply line and a discharge line or return line of a hydronic HVAC system as inputs to a control system operable to maintain a constant pressure drop across the system, or the valve can operate as a temperature independent control valve, utilizing temperature measurements from a supply line and a discharge line or return line of a hydronic HVAC system as inputs to a control system operable to maintain a constant temperature drop across the system.

Description

TECHNICAL FIELD

[0001] The invention described below relates to the field of pressure independent control valves. BACKGROUND

[0002] Current pressure independent control valves used in HVAC systems are installed in high flow applications and operate to maintain a constant differential pressure across a duct system regardless of fluctuations in the supply pressure of the fluid. These valves use a traditional valve disc and seat, and the disc position is varied by the fluid pressure of the fluid flowing through the valve and acting on a diaphragm that is fixed to the valve stem. Applicant's prior U.S. Patent 10,323,768 discloses a pressure independent control valve with an electronic control system that has a compact design in which the main components of the valve, including the seat, closing element, and operating chamber, are contained within a compact disc-shaped valve body. The valve utilizes a flat diaphragm that is directly attached to the closing element. SUMMARY

[0003] The apparatus described below provides for controlling flow through a duct system with a valve that is operable as a pressure independent control valve or a temperature independent control valve. The control valve includes a main valve that uses a ball-shaped closing element that is operable to shift into contact against a seat element. The ball-shaped closing element is fixed to a valve stem that is directly or indirectly fixed to an inversion sleeve or diaphragm that is operable to force the ball-shaped closing element against the seat when pressure is applied to the inversion diaphragm on the side of the diaphragm opposite the ball-shaped closing element and seat. The control valve also includes a pilot valve for controlling the ball-shaped closing element of the main valve. The main valve is controlled in part by high pressure fluid from a high pressure port in the upstream face of the valve or associated duct system being ported through the pilot valve. The pilot valve is controlled by a computer system in response to a differential pressure across the valve or across the associated duct system (in which case it is operable as a pressure independent module or PIM as the term is used in the art), or in response to a sensed temperature differential across the associated duct system (in which case it is operable as a temperature independent module or TIM as the term is used in the art).

[0004] The pilot valve is operable to port high pressure fluid from the system to a chamber behind the diaphragm to force the diaphragm and ball-shaped closing element toward the seat, or to isolate the chamber from high pressure and fluidly connect the chamber to a low pressure area in the system (allowing fluid in the chamber to vent and thus allowing the diaphragm to invert to a non-pressurized configuration that is biased by a spring that is configured to force the inversion sleeve or inversion diaphragm to invert and pull the ball-shaped closing element away from the seat. In this way, the main valve is operable to throttle flow through the valve in response to a pressure or temperature differential sensed by the control system. BRIEF DESCRIPTION OF DRAWINGS

[0005] Figure 1 、 Figure 2 and Figure 3 is a cross-section of a flow control valve.

[0006] Figure 4 is a cross-section of a flow control valve showing a Venturi sensing element that can be used to control the valve.

[0007] Figure 5 is an isometric view of a valve.

[0008] Figure 6 is a schematic view of a piping system (such as an HVAC system) in which the valve of Figure 1 can be used. DETAILED DESCRIPTION

[0009] Figure 1 、 Figure 2 and Figure 3 illustrate a cross-section of a flow control valve 1. The flow control valve is an assembly consisting of a main valve (including a valve seat section 2S and an actuator section 2A) and a pilot valve 3. The main valve section includes a main valve inlet 4 formed in a valve ring or valve annulus 5, which includes the valve seat section, with a bore 6 through the seat section 2S, and includes an outlet 7 on the outlet side of the valve seat section 2S. The inlet side of the valve (item 8) includes the inlet of the ring and includes an inlet orifice 9. The bore 6 extends through the valve seat section 2S and includes a beveled or flared opening into the outlet 7, providing a seating element in the form of a valve seat 10. The valve seat includes the inner wall (bore surface) of the valve seat section 2S adjacent the outlet, which is sized to match the shape of a closure element 11. The closure element is a valve disc or plunger having an outer surface (facing the valve seat) configured to seat against the valve seat and seal. As shown, the main valve closure element is preferably a rounded or spherical surface, perhaps hemispherical, configured to seat against the valve seat.

[0010] The actuator section 2A is disposed outside the valve seat section 2S downstream of the closure element 11 and not within the bore 6 of the valve seat section 2S. A roll-over diaphragm or reverse sleeve 12 disposed within the actuator section is operable to roll over into a reverse configuration (i.e., folded back on itself) to different degrees and is fixed to a valve stem at an end of the valve stem opposite the closure element. The diaphragm is operable to elastically recover or “unroll” longitudinally within a bore 14 of the actuator 2A toward the main valve inlet 4 (as shown in Figure 1 ) by operation of the pilot valve and subsequent pressurization of a main valve operating chamber 13 to translate the closure element 11 toward the valve seat 10 and inlet orifice to (partially or completely) occlude the bore of the valve seat section 2S to control flow rate through the valve seat section, and to reverse to an inside-out configuration (as shown in Figure 2), where the upstream portion of the diaphragm is rolled over within the downstream portion (or vice versa if flow through the valve is reversed relative to the depiction) and pulls the spherical valve disc away from the valve seat to open or block fewer inlet orifices.

[0011] The pilot valve 3 shown in the drawings comprises a closing element, such as a rotatable ceramic disc 15R, secured to a disc drive 16, which is operable to rotate the rotatable disc relative to a fixed disc or flat seating surface 15F. The pilot valve may alternatively be a fast-acting plug valve, ball valve, needle valve, or other suitable valve. Figure 1 The valve depicted is a ceramic disc valve. A motor 17 is operable to rotate the disc so that the orifice(s) 18A, 18B of the rotatable disc 15 move into and out of alignment with the pilot valve inlet 20 and outlet 21 to allow flow into the pilot valve's flow path 19. The pilot valve and its flow path are configured to provide a fluid passage for: (1) pressurized fluid from the pilot valve inlet port 20 on the inlet face 8 of the valve seat section through the aperture of the disc to the pilot valve outlet port 21 and into the main valve operating chamber 13; (2) venting pressure from the main valve operating chamber 13 through the working fluid conduit 23 and the bleed port 22 to the outlet side 7 of the valve seat section 2S; or (3) simultaneously blocking a fluid path from the inlet side of the valve seat section through the pilot valve, a fluid path from the outlet side of the valve seat section through the pilot valve, or a fluid path from the main valve operating chamber 13 to the pilot valve outlet port 22 to the outlet side 7 of the valve seat section 2S. The pilot valve can be operated in on / off mode, as a shut-off valve, or as a throttling valve or a mixing valve. Most conveniently, the valve can be a ceramic disc valve comprising a fixed disc ( Figure 1 Item 15F in the figure), the rotatable disc 15R has one or more orifices that can be positioned to fluidly communicate with the operating chamber 13, the inlet port 20, or the bleed port / pilot valve outlet port 21 to the outlet side 7 of the valve seat section 2S through the working fluid conduit 23 as required to increase or maintain the pressure in the operating chamber or to relieve pressure from the operating chamber to the outlet side of the valve seat section (and, optionally, through the use of a mixing valve, to balance the forces on the face of the diaphragm 12 to maintain the disc in position relative to the valve seat to maintain the desired open, closed or throttled position of the valve). Other pilot valves can also be used, such as needle valves, cylinder valves or ball valves, and these pilot valves can be operated as stop valves or throttling valves.

[0012] In operation, the main valve operating chamber 13 receives pressurized fluid from the pilot valve 3 through the pilot valve output port 21 and discharges pressurized fluid from the main valve operating chamber 13 through the pilot valve outlet port 22, and both the fluid supply and discharge from the operating chamber 13 can be through a single working fluid conduit 23. The working fluid conduit 23 serves as a path for working fluid to flow from the pilot valve output port 21 to the operating chamber to translate the closure element in a first direction (closed in the example shown in the drawings) and as a path for working fluid to discharge from the operating chamber back to the pilot valve output port 21 and thus through the bleed port 22 to translate the closure element in a second direction (open in the example shown in the drawings). The working fluid conduit 23 passes from its connection with the pilot valve near the valve seat region through an aperture in the opening of the associated piping to the actuator region and is preferably not enclosed within the valve body that encloses both the valve seat region and the actuator region (although the valve seat region and the actuator region can be enclosed within a housing or valve body that fits between the inlet pipe 41 and the outlet pipe 42).

[0013] Figure 1 The control valve is shown in a fully closed configuration, Figure 2 The valve is shown in a fully open configuration. In Figure 1 In the configuration shown in Fig. 2, the pilot valve 3 is open in a first position to transmit high pressure fluid from the inlet side of the valve through the pilot valve inlet port 20 on the inlet side of the valve and through the pilot valve bore 19, through the pilot valve outlet port 21, through the working fluid conduit 23, and into the main valve operating chamber 13. With the main valve operating chamber pressurized by fluid from the inlet side of the valve, the diaphragm 12 and the ball valve disc 11 are forced toward the outlet orifice and valve seat (despite the high pressure applied to the seating surface of the ball valve disc by the fluid flow) across the entire area of the face of the diaphragm exposed to the chamber pressure (which is greater than the area of the ball valve disc facing the valve seat) to partially or completely close the valve. In Figure 2 In the configuration shown in Fig. 3, the pilot valve 3 is open in a second position positioned to block high pressure fluid from the inlet side from reaching the main valve operating chamber 13 while opening a flow path from port 21 to the bleed port 22 so that fluid in the main valve operating chamber is bled out through port 21, the bleed port 22, and through the working fluid conduit 23 into the outlet side of the valve, out of the operating chamber. With the main valve operating chamber depressurized, the diaphragm 12 and the ball valve disc 11 are forced by the force of the spring 24 (compression spring) that biases the diaphragm to the extended configuration to push the piston 25 off the inner wall of the upstream end 2U of the actuator housing and thus off the valve seat region and thereby move (pull) the closure element away from the valve seat while urging the anti-flip sleeve to flip further back, back to its more fully flipped configuration, folded back on itself, as in Fig. 4. Figure 2If the spring is not provided, the pressure of the inlet fluid on the inlet side of the valve can be sufficient to push the closing element 11 away from the outlet orifice and valve seat (depending on the residual pressure behind the diaphragm) to partially or completely open the valve. A tension spring fixed to the piston of the actuator section 2A and to the downstream end 2D can also be used instead of the compression spring shown.

[0014] Figure 3 The control valve is shown in a third intermediate configuration, partially closed or partially open, to throttle the fluid flow through the valve seat section 2S. In Figure 3 the configuration shown in Fig. 2, the pilot valve is in a third position "closed", closing both the flow path from the pilot valve inlet port 20 and the flow path to the bleed port 22. Thus, high pressure fluid from the inlet side of the valve cannot enter the operating chamber, and the fluid in the operating chamber cannot escape to the low pressure side of the valve, and the valve is hydraulically locked in the intermediate position. To achieve the intermediate position, the valve is operated from its initial position by either transmitting high pressure fluid into the operating chamber 13 to push the closing element 11 towards the valve seat 2S Figure 1 ), or transmitting high pressure fluid out of the operating chamber 13 to allow the spring to push (or pull) the closing element 11 away from the valve seat Figure 2 ); and blocking the flow into or out of the operating chamber 13 when the desired intermediate position is reached. The diaphragm can be biased to the inverted configuration with a biasing element, such as a spring 24, acting on the upstream surface 2U of the actuator cylinder to bias the diaphragm, preferably by acting on a piston 25 fixed to the central portion of the inverted sleeve at a first (downstream) end and to a shaft 26 at a second (upstream) end. The pressure in the operating chamber can cause the sleeve to unfold and invert (in the upstream direction) and the piston, shaft and closing element to translate towards the valve seat section, while the release of pressurized fluid in the operating chamber and the expansion force of the spring can cause the sleeve to fold and invert (in the downstream direction) and the piston, shaft and closing element to translate away from the valve seat section. The spring can be omitted if the expected flow in the outlet pipe is expected to be strong enough to force the closing element away from the valve seat section at a sufficient speed for the particular use. The preferred spring shown in the drawings is a helical compression spring, where each turn of the helix fits inside the previous turn, so that if fully compressed as in Fig. 1 Figure 1 , the spring will form a 2D helix (the projection of the spring on the wall 2U will be a helix), while if uncompressed as in Fig. 2 Figure 2 , the turns will define a cone. The spring can be a helical coil spring (with equal diameter between turns, so that the turns will define a cylinder with constant diameter, and the projection of the spring on the wall 2U will be a circle).

[0015] The valve shown in the drawings can be operated to achieve: (1) a first configuration of the valve in which the pilot valve is configured to transmit high pressure fluid from the pilot valve inlet port 20 to the main valve operating chamber 13 to cause the roll-over diaphragm 12 to recover to an unrolled configuration and thereby force the closure element 11 toward the valve seat region 2S, as shown in Figure 1 ; or (2) a second configuration of the valve in which the pilot valve is configured to transmit fluid from the main valve operating chamber 13 to the bleed port 22 to cause the roll-over diaphragm 12 to invert to a roll-over configuration and thereby force the closure element 11 away from the valve seat region 2S; or (3) a third configuration of the valve in which the pilot valve is configured to block fluid flow into and out of the main valve operating chamber 13, preventing diaphragm inversion or recovery, and thereby hydraulically locking the main valve operating chamber 13 to maintain the closure element in an intermediate position relative to the valve seat region between the fully closed position and the fully open position. Note that the terms invert and recover are elected in the sense of assuming one surface of the diaphragm (the operating chamber side) is the inside surface and the other surface is the outside surface.

[0016] The diaphragm can comprise silicone rubber, EPDM rubber (preferably peroxide vulcanized), etc., preferably reinforced with fiber. The closure element can comprise a hard, non-compliant material (metal or plastic) or a resilient material. The inlet orifice 9, seating element 10, closure element 11, bore 6, diaphragm 12, and operating chamber 13 are preferably aligned along a common longitudinal axis L through the valve that is generally perpendicular to the plane P established by the disc. As shown in the drawings, the common longitudinal axis L is preferably centered in the flow path of the surrounding conduit 41 so that each component is centered relative to the bore 6 of the valve and aligned along the central longitudinal axis of the valve seat region. As shown in the drawings, the diaphragm is configured to invert or roll over into an outside-in configuration (like a rolled-up shirt sleeve), as shown in Figure 2 , and recover or unroll into a non-inverted configuration, as shown in Figure 1 .

[0017] Figure 4 is a cross-section of a flow control valve showing a Venturi sensing element that can be used to control the valve. This view shows the valve 1 with the main valve of the valve including the valve seat region 2S, actuator region 2A, inlet orifice 9 on the inlet side (item 8) of the valve seat region 2S, ball valve disc 9, diaphragm 12, and main valve operating chamber 13, among other components. The pilot valve is not visible in this cross-section.

[0018] Figure 4A pressure sensor, such as a differential pressure sensor 27, is shown in fluid communication with a low pressure sensing port 28 disposed in the inlet orifice inner wall of the valve annulus 5 bore including the valve seat section downstream of the inlet orifice 9. The sensing port is communicated to the pressure sensor 27 by a low pressure sensing line 28L. A high pressure sensing port 29 on the inlet face of the valve is exposed to the inlet fluid pressure, in communication with the pressure sensor 27 by a high pressure sensing line 29L. The inlet orifice can be shaped such that the inlet orifice forms a Venturi or orifice plate by which the flow rate through the valve can be measured with inputs from the pressure sensor 27 sensing (1) the inlet pressure through the inlet pressure sensing port 29 as a high pressure input and (2) the pressure from the low pressure sensing port 28 as a low pressure input for calculating the flow rate through the valve. The bore defines a central radial portion of the valve seat section and the remainder of the valve seat section defines an outer radial portion of the valve seat section and the valve seat section is characterized by a sidewall that circumscribes the valve seat section and the valve further includes a pressure sensor 27 disposed in the outer radial portion and ports 28, 29 or other ports disposed on the valve seat section that are exposed to the fluid flow and in fluid communication with the sensor. The pressure sensor can be configured in a sensor assembly including separate high pressure sensor 27H and low pressure sensor 27L and can be inserted into a radially oriented bore in the valve seat section with a first pressure sensing port 28 opening to the inlet orifice and a first sensing line 28L extending through the valve seat section to a first pressure sensor 27L and a second pressure sensing port 29 opening to the inlet side of the valve and a second sensing line 29L extending through the valve seat section to a second pressure sensor 27H.

[0019] Low pressure sensing can be improved, especially for small flow configurations of the valve that induce high turbulence near the longitudinal center of the valve seat section or near the small diameter region of the Venturi configuration, by adding a conduit 30 radially extending through the valve bore in the low pressure region adapted to receive the low pressure input for the Venturi pressure sensor and in fluid communication with the low pressure region by one or several ports 31 in the conduit that open the bore of the valve seat section in the low pressure region of the flow through the valve.

[0020] As shown, the valve comprises a separate valve seat section and a separate actuator section without a valve body or housing through which fluid flows. The valve can be installed in a pipeline, with the actuator section disposed within the outlet section of the pipeline. The actuator section is positioned and secured in axial alignment with the valve seat section using one or more supports 32 or other convenient means. The valve seat section is configured such that, when installed in a pipeline system (with the valve seat section positioned between the inlet and outlet pipes, also shown in the accompanying drawings), the longitudinal axis L of the orifice is aligned with the longitudinal axis of the surrounding, adjacent pipeline system. The one or more supports are configured to secure the actuator section in the pipeline system, spaced apart from the valve seat section, such that, with the actuator section suspended within the pipeline system, the inlet orifice, closure element, diaphragm, and operating chamber are aligned along the longitudinal axis L of the valve seat section. The working fluid conduit includes a tube 23 that provides a fluid path from the pilot valve outlet port to the main valve operating chamber within the actuator section. The tube extends outwardly from the valve seat section to the main valve operating chamber. The valve seat area, the actuator area, and the tube are not enclosed in a separate valve body, and the tube passes through a portion of the piping system outside the valve seat area and the actuator area.

[0021] Figure 5 1 is a perspective view of a flow control valve 1, which includes a valve seat section 2S, a valve actuator 2A and a support 32 connecting the two, and a pilot valve 3. This view also shows the inlet side 8 of the valve seat section, the inlet orifice 9 and the pilot valve inlet port 20. The first sensing port 29 (for inlet pressure sensing) and the low pressure sensing port 28 are also shown. Figure 5 As shown in FIG, the pilot valve 3 and the pressure sensor assembly 27 can be conveniently arranged on the valve ring 5 (in the valve seat area 2S, between the inlet side flange 33 and the outlet side flange 34 for fixing the valve to the relevant piping system). Figure 6 ) is operably connected to various inputs and sensors for receiving signals corresponding to the pressures sensed by the sensors, and the control system is also operably connected to the motor 17 for operating the pilot valve. The control system can control the pilot valve and thereby the main valve in response to the flow through the valve determined by the control system based on the sensed pressure from the port of Venturi or the temperature at various points in the associated piping system, or in response to other inputs from additional sensors, or in response to manual input from an operator. The control system can be disposed between the flanges of the valve without protruding beyond the periphery of the flanges, or the control system can also be remotely located. The pressure sensor is shown as being disposed within the peripheral area of ​​the valve, with the pressure sensor port communicating from the pressure sensor port. A temperature sensor can also be disposed within the peripheral area of ​​the valve, with the temperature sensor port communicating from the inlet or outlet side (or other location) of the valve to the temperature sensor.

[0022] The valve can be used as a PIM, utilizing a pilot valve to control flow through the valve to maintain a constant pressure drop across the valve itself, or to maintain a constant pressure drop across the associated piping system. A control system is shown schematically in Figure 6 The control system is programmed to accept signals from low pressure sensor 27L and high pressure sensor 27H corresponding to the pressures sensed by the respective sensors and to determine the pressure differential between the associated sensed ports 28 and 29 and to compare the determined pressure differential to a predetermined pressure differential and then conditionally cause the pilot valve motor to energize to open or close (or throttle) the pilot valve as needed to close or open the main valve to maintain a sensed pressure differential matching the predetermined pressure differential (within an acceptable band around the predetermined pressure differential). The predetermined pressure differential can be preset at the time of manufacture of the system or input into the control system by an installer or user.

[0023] To maintain a constant pressure drop across the valve itself, a control system and sensors built into the valve can be used. To maintain a constant pressure drop across the associated piping system, pressure sensors disposed in the associated system can be used, and a high pressure sensor can be included at the input of the associated piping system and a low pressure sensor at the output of the associated piping system. If the valve is installed downstream of the associated piping system, the sensor 27 used to sense high pressure when the valve is used alone can be used as the low pressure sensor for the associated piping system. If the valve is installed upstream of the associated piping system, the sensor 28 used to sense high pressure when the valve is used alone can be used as the high pressure sensor for the associated piping system, and a low pressure sensor at the outlet of the associated piping system can be used by the control system as the low pressure sensor.

[0024] The valve can be used as a temperature independent control valve or temperature independent module (TIM), utilizing a pilot valve to control flow through the valve to maintain a constant temperature drop across the associated piping system. To operate as a temperature independent control valve or temperature independent module (TIM), Figure 6 The control system shown in

[0025] Figure 6 An overall piping system is illustrated, the piping system having a valve 1 controlling flow through the associated piping system 40, such as an HVAC system, in which Figure 1A valve of the type described can be used. The valve is installed in a piping system, with an upstream inlet pipe 41 and a downstream outlet pipe 42 establishing respective upstream and downstream sides of the flow control valve. The system can include a supply line 43, any number of branch valves 44 in different branches for regulating flow to different loads 45, and an outlet line 46 (which is the initial portion of a return line). The control valve 1 is installed in the return line, which includes the outlet line 46, the upstream pipe 41 and the downstream pipe 42, and the remainder of the return line (item 47). In an HVAC system, the branch valves can be inexpensive pressure independent control valves (such as Griswold and PIM valves), manually operated ball valves or throttling valves, or other valves, and the loads can be individual heat exchangers or rooms to be supplied with fluid through a main supply, manifold, or bank of branch valves. When used as a PIM to control flow through the associated piping system, the high pressure input is taken from a pressure sensor 48 on the supply line 43, and the low pressure input can be taken from a pressure sensor 49 disposed near the inlet to the valve or in the valve (which serves as a high pressure sensor when the valve is used to control pressure drop across the valve itself), or from a pressure sensor disposed in the return line of the associated piping system.

[0026] When used as a temperature independent control valve or temperature independent module (TIM) to control flow through the associated piping system (in this case an HVAC cooling system), the inlet temperature input is taken from a temperature sensor 50 on the supply line 43, and the outlet temperature input can be taken from a temperature sensor 51 disposed on the outlet of the associated piping system or from a temperature sensor disposed in the return line of the associated piping system. (When used for cooling, the temperature sensor 50 will serve as a high temperature sensor, and the temperature sensor 51 will serve as a low temperature sensor.) The valve can be operated in another mode in which the valve is throttled as needed to maintain the temperature at the outlet of the associated piping system, independent of the temperature differential across the system.

[0027] When used to control flow across a piping system, the control system can be operable to control a pilot valve, and the control system can be operable to receive signals from first and second sensors related to fluid in the system controlled by the valve, and to control the pilot valve to in turn control the main valve to in turn control flow through the valve in response to the signals from the first and second sensors. Where a load is between the inlet and the outlet, the respective sensors can be disposed near the outlet (return line) of the piping system and the inlet (supply line) of the piping system. Depending on the location of the valve within the piping system, the sensors within the valve can serve as input sensors or output sensors.

[0028] While preferred embodiments of the devices and methods have been described with reference to the environment in which they were developed, the preferred embodiments are merely illustrative of the principles of the present application. Elements of different embodiments can be combined into each other kind to obtain the benefits of elements combined with such other kinds, and different advantageous features can be used, either alone or in combination, in embodiments. Other embodiments and configurations can also be devised without departing from the spirit of the present application and the scope of the appended claims.

Claims

1. A flow control valve comprising: a main valve, the main valve comprising a valve seat section, the valve seat section comprising: an inlet orifice (9) and an outlet orifice (7) and a bore (6) extending from the inlet orifice to the outlet orifice (7), the outlet orifice (7) forming a valve seat (10); a closure element (11), and an actuator section (2A) operable to move the closure element (11) into and out of or towards and away from a blocking relationship with the valve seat (10); the actuator section (2A) comprising a roll-lift diaphragm (12) fixed to the closure element (11), the roll-lift diaphragm (12) forming a main valve operating chamber (13) within the actuator section (2A) operable by pressurisation of the main valve operating chamber (13) to translate the closure element (11), wherein the roll-lift diaphragm (12) is disposed within the actuator section (2A); the actuator section (2A) is fixed to the valve seat section (2S) by one or more supports (32) such that the actuator section (2A) is disposed downstream of and spaced apart from the valve seat section (2S); a pilot valve (3) disposed within the valve seat section (2S), the pilot valve having a pilot valve inlet port (20) to an inlet side (8) of the valve seat section (2S), the pilot valve inlet port (20) being in fluid communication with the main valve operating chamber (13) through the pilot valve, the pilot valve being operable to control fluid flow from the inlet side (8) of the valve seat section (2S) to the main valve operating chamber (13); wherein the valve seat section (2S) is configured such that, when installed in a piping system (40) between an inlet pipe and an outlet pipe, the longitudinal axis (1) of the bore is aligned with the longitudinal axis of the piping system and the one or more supports (32) are configured to fix the actuator section (2A) spaced apart from the valve seat section (2S) in the piping system (40) such that the inlet orifice (9), the closure element (11), the roll-lift diaphragm (12) and the main valve operating chamber (13) are aligned along the longitudinal axis of the valve seat section (2S); and further comprising a tube (23) providing a fluid path from a pilot valve outlet port (21) to the main valve operating chamber (13) within the actuator section (2A), the tube extending outwardly from the valve seat section (2S) to the main valve operating chamber (13), wherein the valve seat section, the actuator section and the tube are not enclosed within a valve body.

2. The flow control valve of claim 1, wherein: the pilot valve (3) further comprises a pilot valve outlet port (21) to a bleed port (22) on an outlet side of the valve seat section (2S), the bleed port (22) being in fluid communication with the main valve operating chamber (13) through the pilot valve, the pilot valve being operable to control fluid flow from the main valve operating chamber (13) to the outlet side of the valve seat section.

3. The flow control valve of claim 1, wherein: In the first configuration of the flow control valve, the pilot valve is configured to transmit high pressure fluid from the pilot valve inlet port (20) to the main valve operating chamber (13) to urge the roll-over diaphragm (12) to roll over and thereby force the closing element (11) toward the valve seat section (2S).

4. The flow control valve of claim 2, wherein: In the first configuration of the flow control valve, the pilot valve is configured to transmit high pressure fluid from the pilot valve inlet port (20) to the main valve operating chamber (13) to urge the roll-over diaphragm (12) to roll over and thereby force the closing element (11) toward the valve seat section (2S).

5. The flow control valve of claim 2, wherein: In the second configuration of the flow control valve, the pilot valve is configured to transmit fluid from the main valve operating chamber (13) to the bleed port (22) to urge the roll-over diaphragm (12) to roll over and thereby force the closing element (11) away from the valve seat section (2S).

6. The flow control valve of claim 4, wherein: In the third configuration of the flow control valve, the pilot valve is configured to block fluid flow into and out of the main valve operating chamber (13), to prevent the roll-over diaphragm from rolling over and thereby hydraulically lock the main valve operating chamber (13) to maintain the closing element in an intermediate position relative to the valve seat section.

7. The flow control valve of claim 1, wherein, The longitudinal axis of the valve seat section is a central longitudinal axis of the valve seat section.

8. The flow control valve of claim 1, wherein, The bore defines a central radial portion of the valve seat section, and the remaining portion of the valve seat section defines an outer radial portion of the valve seat section, and the valve seat section has a side wall that bounds the valve seat section, and the flow control valve further comprises: a sensor disposed in the outer radial portion; and a port disposed on the valve seat section that is exposed to fluid flow and is in fluid communication with the sensor.

9. The flow control valve of claim 1, wherein, The inlet orifice includes an opening in an inlet side of the flow control valve, the opening having an inlet orifice inner wall that bounds the inlet orifice and is proximate the inlet side, and the flow control valve further comprises: a pressure sensor (27); a first pressure sensing port (28) disposed in the inlet orifice inner wall and in fluid communication with the pressure sensor (27); a second pressure sensing port (29) disposed on the inlet side of the valve seat section and in fluid communication with the pressure sensor (27); by which pressures sensed by the pressure sensor (27) through the first pressure sensing port (28) and through the second pressure sensing port (29) can be used to measure flow through the flow control valve.

10. The flow control valve of claim 1, wherein, The closing element is a ball-shaped disc sized and dimensioned to seat against the valve seat and control flow through the valve seat section.

11. The flow control valve of claim 1, further comprising: a first pressure sensing port (28) to the inlet orifice, and a first sensing line (28L) extending through the valve seat section to a first pressure sensor (27L); and a second pressure sensing port (29) to the inlet side of the flow control valve, and a second sensing line (29L) extending through the valve seat section to a second pressure sensor (27H).

12. The flow control valve of claim 11, wherein, A first pressure sensor (27L) is disposed in a radially oriented bore extending parallel to a plane defined by the valve seat section within a peripheral region of the valve seat section, and a second pressure sensor (27H) is disposed in a radially oriented bore extending parallel to the plane defined by the valve seat section within the peripheral region of the valve seat section.

13. The flow control valve of claim 9, further comprising: a first temperature sensor disposed within a peripheral region of the flow control valve, and a temperature sensor port communicating from an inlet side or an outlet side of the flow control valve to the temperature sensor.

14. A flow control valve and control system assembly, comprising: the flow control valve of claim 1 ; a first sensor and a second sensor; and a control system operable to control the pilot valve, the control system operable to receive signals from the first and second sensors related to fluid in a system controlled by the flow control valve and to control the pilot valve to in turn control the main valve to in turn control flow through the flow control valve in response to the signals from the first and second sensors.

15. An HVAC system, comprising: the flow control valve of claim 1 ; a first sensor and a second sensor; a control system operable to control the pilot valve, the control system operable to receive signals from the first and second sensors related to fluid in a system controlled by the flow control valve and to control the pilot valve to in turn control the main valve to in turn control flow through the flow control valve in response to the signals from the first and second sensors; and and a duct system including a supply line, a return line, and at least one load between the supply line and the return line; wherein: the first sensor is a pressure sensor in fluid communication with the supply line; the second sensor is a pressure sensor in the return line; the flow control valve is disposed in the supply line or the return line in the duct system; and the control system is programmed to control flow through the flow control valve to maintain a predetermined pressure differential between the first and second sensors.

16. An HVAC system, comprising: the flow control valve of claim 1 ; a first sensor and a second sensor; a control system operable to control the pilot valve, the control system operable to receive signals from the first and second sensors related to fluid in a system controlled by the flow control valve and to control the pilot valve to in turn control the main valve to in turn control flow through the flow control valve in response to the signals from the first and second sensors; and a duct system including a supply line, a return line, and at least one load between the supply line and the return line; wherein: the first sensor is a temperature sensor operable to sense a temperature of fluid in the supply line; the second sensor is a temperature sensor operable to sense a temperature of fluid in the return line; the flow control valve is disposed in the supply line or the return line in the duct system; and the control system is programmed to control flow through the flow control valve to maintain a predetermined temperature differential between the first and second sensors.

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