Abstract:
A flow control valve assembly has at least one manifold having an inlet flow port, an outlet flow port, and a flow channel provided therebetween, the flow channel having an inlet chamber, a variable area chamber and an outlet chamber, with fluid flowing from the inlet flow port to the inlet chamber, the variable area chamber and the outlet chamber, in that order, before exiting the outlet flow port. The flow control valve assembly also includes a float assembly extending inside the flow channel, the float assembly having a float that is limited for its movement inside the variable area chamber, a measuring device which measures the displacement of the float, and a connecting rod which connects the float to the measuring device. A bracket assembly is secured to the inlet chamber inside the flow channel, with the measuring device retained by the bracket assembly.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to the control and measurement of flowrates for fluids, and in particular, to an assembly for controlling and measuring or sensing the flowrate of fluids. 
     2. Description of the Prior Art 
     A rotameter is a well-known device that measures the flowrate of fluid in a closed tube. It belongs to a class of meters called variable area meters, which measure flowrate by allowing the cross-sectional area of the fluid traveling through, to vary, causing a measurable effect. Unfortunately, rotameters cannot be used to measure flowrate at high pressures because they are typically made out of glass. 
     There are also other techniques and devices to measure flowrates, for example, turbine meters and venturi tubes (delta P). However, these devices do not accurately measure flowrates at the low end (e.g., turn-down ratios below 20-to-1) of the flow. 
     Thus, there remains a need to provide a device for accurately measuring fluid flowrates, even at high pressures. 
     SUMMARY OF THE DISCLOSURE 
     In order to accomplish the objects of the present invention, there is provided a flow control valve assembly having at least one manifold having an inlet flow port, an outlet flow port, and a flow channel provided between the inlet flow port and the outlet flow port, the flow channel having an inlet chamber, a variable area chamber, and an outlet chamber, with fluid flowing from the inlet flow port to the inlet chamber, the variable area chamber and the outlet chamber, in that order, before exiting the outlet flow port. The flow control valve assembly also includes a float assembly extending inside the flow channel, the float assembly having a float that is limited for its movement inside the variable area chamber, a measuring device which measures the displacement of the float, and a connecting rod which connects the float to the measuring device. A bracket assembly is secured to the inlet chamber inside the flow channel, with the measuring device retained by the bracket assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of a flow control valve assembly according to one embodiment of the present invention shown in use with multiple output flow channels. 
         FIG. 1B  is a perspective view of a flow control valve assembly according to another embodiment of the present invention shown in use with a single output flow channel, with the inlet flow port on the opposite side of the outlet flow port. 
         FIG. 1C  is a perspective view of a flow control valve assembly according to another embodiment of the present invention shown in use with a single output flow channel, with the inlet flow port on the same side as the outlet flow port. 
         FIG. 2  is a cross-sectional side view of the assembly of  FIG. 1A  adapted for use with multiple output flow channels. 
         FIG. 3  is an exploded view of the assembly of  FIG. 2 . 
         FIG. 4  is a cross-sectional side view of the assembly of  FIG. 1B  adapted for use with a single output flow channel. 
         FIG. 5  is a front view of the assembly of  FIG. 4 . 
         FIG. 6  is a rear view of the assembly of  FIG. 4 . 
         FIG. 7  is a perspective view of the float assembly of the assembly of  FIGS. 1A, 1B , and  1 C shown with a compression spring. 
         FIG. 8  is a side view of the float assembly of  FIG. 7  shown without a compression spring. 
         FIG. 9  is a side view of the float assembly of  FIG. 7  shown with a partial compression spring. 
         FIG. 10  is a side view of the float assembly of  FIG. 7  shown with a full compression spring. 
         FIG. 11A  is an exploded sectional view of a conventional linear variable differential transformer (LVDT). 
         FIG. 11B  is an electrical diagram for the LVDT of  FIG. 11A . 
         FIG. 12  is an exploded view of a valve sleeve and valve spool that can be used with the assembly of  FIGS. 1A, 1B and 1C . 
         FIG. 13A  is an enlarged sectional view illustrating the float in a rest position. 
         FIG. 13B  is an enlarged sectional view illustrating the float being displaced from the rest position during fluid flow. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims. In certain instances, detailed descriptions of well-known devices and mechanisms are omitted so as to not obscure the description of the present invention with unnecessary detail. 
       FIGS. 1A, 1B, and 1C  illustrate the flow control valve assembly  100  as used in an application for multiple output flow channels ( FIG. 1A ) and a single output flow channel ( FIGS. 1B and 1C ). There are two ports  108  and  122  that can be used as an inlet flow port and can be fluidly coupled with a header manifold for multiple outlet flows. The unused port can be plugged or used with a pressure control circuit, which controls the inlet flow pressure. 
     Referring to  FIG. 1A , inlet flow is delivered via an inlet flow tube  102  into a header manifold  104  for distributing the inlet flow, and to which each flow control valve assembly  100  is fluidly coupled. For example, referring to  FIGS. 2 and 3 , each assembly  100  has a feedback manifold  105  and a flow control manifold  106 . Each feedback manifold  105  has an inlet flow port  108  which is fluidly coupled to inlet flow in the header manifold  104 . The inlet flow port  108  is coupled to an inlet chamber  110  having PQT (Pressure, Flowrate, and Temperature) transducers in the feedback manifold  105 . The inlet chamber  110  is in turn fluidly coupled to a variable area chamber  112  in the flow control manifold  106 , and then the variable area chamber  112  is fluidly coupled to an outlet chamber  114 . 
     A valve sleeve  116  and a matching valve spool  118  are seated inside the outlet chamber  114  to control the flow of the outflowing fluid. The valve sleeve  116  has configurable orifices  198  as shown in  FIG. 12 . The valve spool  118 , controlled by the actuator  190 , moves relative to the valve sleeve  116  to control the overall outflow orifice area, which in turn controls the flowrate. An outlet flow port  120  is fluidly coupled to the outlet chamber  114  through the valve spool  118  and valve sleeve  116  to allow the fluid to flow to the outflow path. The outflow orifice area concept includes providing, strategically positioning, and sizing multiple hole or orifice arrangements in the valve sleeve  116  to meter the desired flowrate. 
     An actuator  190 , typically a solenoid driven, can be coupled to the valve spool  118  to drive the desired spool position. An optional actuator position feedback  192  (e.g., an LVDT) can also be coupled to the actuator  190  for providing feedback of the actuator position. 
     Referring to  FIGS. 4-6 , for the single output flow channel embodiments shown in  FIGS. 1B and 1C , the inlet flow is coupled directly to the inlet flow port  108  of the feedback manifold  105 . 
     Referring back to  FIGS. 2 and 3 , the feedback manifold  105  includes the electronics and sensors for measuring Pressure, Flowrate, and Temperature. The LVDT sensor wires are channeled from the inlet chamber  110  to the electronic enclosure  180  (dry area). The LVDT sensor wires are protected against the fluid flow by either upper mounting bracket  130  or lower mounting bracket  132  depending on how the LVDT  134  is orientated. In addition, a pressure control circuit can be built-in to the feedback manifold  105  to control the specific inlet flow pressure. A similar pressure control circuit can be incorporated with the header manifold  104  to control the common inlet flow pressure. The inlet chamber  110  has a generally cylindrical configuration and is adapted to receive the upper mounting bracket  130  and the lower mounting bracket  132  of the float assembly  128  of  FIG. 7 . 
     Referring to  FIGS. 7-10 , the float assembly  128  includes an LVDT  134  which has opposite ends retained by the upper mounting bracket  130  and the lower mounting bracket  132 . Referring also to  FIG. 11A , the LVDT  134  has a coil assembly  136  and a core  138 . The core  138  has a cylindrical bore extending therethrough, with a connecting rod  140  having a lower end extending through an upper part of the bore of the LVDT  134 . A float  142  is secured to the upper end of the connecting rod  140 . A mounting spring  144  is provided on the lower mounting bracket  132  to provide support to the coil assembly  136 , to absorb vibrations, and to take out slack. An extension rod  146  extends from a lower part of the cylindrical bore of the core  138 , and terminates at a stop  148 . An extension rod spring  150  is provided on the extension rod  146  between the stop  148  and the lower mounting bracket  132 . In  FIG. 8 , the extension rod spring  150  is not shown and is therefore omitted. In  FIG. 9 , the extension rod spring  150  is provided as a partial spring. In  FIG. 10 , the extension rod spring  150  is provided as a full spring. The purpose of the extension rod springs  150  is to shorten the float&#39;s  142  travel. A full spring could be comprised of multiple springs, each with different compression values, and these added springs must be included as a part of the balanced energy equation. 
     The LVDT  134  is used to measure the displacement or movement of the float  142 . As shown in  FIG. 11B , the coil assembly  136  consists of a primary winding  1600  centered between a pair of identically wound secondary windings  1620  that are symmetrically spaced about the primary winding  1600 . The coils are typically wound on a one-piece hollow form of thermally stable glass reinforced polymer, encapsulated against moisture, wrapped in a high permeability magnetic shield, and then secured in a cylindrical stainless steel housing. The coil assembly  136  is usually the stationary element of the LVDT, with the core  138  being the moving element. The core  138  can be a separate tubular armature of magnetically permeable material, which is free to move axially within the hollow bore defined by the coil assembly  136 . The core  138  is connected to the float  142  via the connecting rod  140 . In operation, the primary winding  1600  is energized by alternating current of appropriate amplitude and frequency. The LVDT&#39;s electrical output signal is the differential AC voltage between the two secondary windings  1620 , which varies with the axial position of the core  138  within the coil assembly  136 . In the present invention, the wires of the coil assembly  136  are in a high pressure flow channel (wet) and they are subjected to fluid flow velocity as high as 30 feet per second. The mounting brackets  130  and  132  are designed to protect the signal wires  152  (see  FIG. 7 ) from fluid flow velocity. 
     The float  142  can be configured in any shape and is used to measure the fluid flowrate using the rotameter or variable orifice area concept when mounted without spring compression. The density of the float  142  must be greater than the fluid density if a compression spring is not added. If an extension rod spring  150  is added in compression (see below), the density of the float  142  can be greater or less than the fluid density, but the flowrate computation must include the spring forces along its axis. 
     The mounting brackets  130  and  132  are mounted adjacent the upper end of the inlet chamber  110 , and provide a solid stop or securement mechanism for the LVDT  134  to prevent the coil assembly  136  from moving during fluid flow. Signal wires  152  are coupled to the core  138  and are channeled through either the upper mounting bracket  130  or the lower mounting bracket  132  in a protective mode. 
     The connecting rod  140  and the extension rod  146  should not be made of magnetized, ferromagnetic, or high conductivity metals, but instead can be made of plastic or other non-conducting materials. One example is an AISI 300 series austenitic (non-magnetic) stainless steel which prevents distortion of the LVDT magnetic field. 
     The extension rod spring  150  allows the size of the manifolds  105  and  106 , and their chambers  110 ,  112  and  114 , to be minimized. This can be important where space is limited. The extension rod spring  150  functions to limit the displacement of the float  142  while achieving the same flowrate. However, the flowrate computation must include the spring force along its axis. 
     The present invention uses the principles (and equations) of conservation of energy to balance the float  142 , and the continuity equation to compute the flowrate. The position of the float  142  is detected by the LVDT  134  in the form of its actual displacement from its rest position (see  FIG. 13A ) which is a reference point, and then the LVDT  134  calculates the flow opening area  200  or variable orifice area (see  FIG. 13B ), which is actually the circumferential space between the tapered wall and the ball of the float  142 . The position of the float  142 , measured by the LVDT  134 , defines the flowrate. At any float position, the total summation of forces acting on the float  142  is balanced.
 
Σ Fy=Fd+Fb−W+/−Fs+Fm= 0
 
where Fy is the vertical force, Fd is the drag force, Fb is the buoyancy force, W is the weight of the float  142 , Fs is the spring force in tension/compression, and Fm are the miscellaneous forces which are negligible.
 
     The fluid energy equation is: ½*v 2 /g+Z+P/(ρ*g)=Constant at any point of reference 
     where v is the fluid velocity, g is the gravity constant, Z is the potential energy, P is the pressure, and ρ is the density of the fluid. 
     The continuity equation is: Flow Q=v a *A a =V b *A b , 
     where A a  is the flow area at the inlet of the neck region  162 , A b  is the flow opening area  200  around the float  142 , v a  is the fluid velocity at the inlet of the neck region  162  and v b  is the fluid velocity at the flow opening area  200  around the float  142 . 
     Referring back to  FIG. 2 , the variable area chamber  112  of the flow control manifold  106  has a tapered inflow section  160 , a neck region  162 , and a tapered outflow section  164 . The tapered inflow section  160  starts with its largest diameter at the bottom of the flow control manifold  106  where the fluid flow enters the variable area chamber  112  from the inlet chamber  110 , and then gradually tapers to its smallest diameter where it transitions to the neck region  162 , and then the variable area chamber  112  transitions from the neck region  162  to the tapered outflow section  164  which starts with its smallest diameter at the transition from the neck region  162  and gradually tapers to its largest diameter adjacent the transition to the outlet chamber  114 . The outlet chamber  114  has a generally cylindrical configuration and is adapted to receive the valve spool  118  and the valve sleeve  116 . 
     The float  142  is retained in the tapered outflow section  164  and adapted to rest on the neck region  162  when there is no fluid flow. The connecting rod  140  extends through the neck region  162  and through the tapered inflow section  160  to the LVDT  134  that is retained in the inlet chamber  110 . The inward taper in the tapered inflow section  160  is designed to increase the velocity of the fluid at the location of the neck region  162 , where the float  142  is located. The increased velocity will increase the kinetic energy of the fluid entering the neck region  162 . Once the float  142  is lifted or moving, it will reach an equilibrium point, where the energy on the float  142  is balanced. The outward taper of the tapered outflow section  164  creates an increasing or variable flow area, thus decreasing the velocity of the fluid, and functions to limit the distance traveled by the float  142 . 
     As a result, energy is conserved at any position occupied by the float  142 . In this application, the major forces acting on the float  142  are: (i) the weight of the float  142 , (ii) the buoyancy force from the fluid, (iii) the fluid pressure acting upon the cross-sectional area of the float  142  or drag force, and (iv) the spring force if applicable. Other forces are assumed to be negligible. When there is no flowrate, the float  142  rests at the bottom of the tapered outflow section  164  at the neck region  162  (the “rest” position). This is the reference point of the measurement taken by the LVDT  134 . At this point, the weight and buoyancy forces are being balanced by the normal force (action is equal to reaction) at the tapered outflow section  164 . When there is a flowrate, the float  142  will be raised to a certain position in the tapered outflow section  164  away from the neck region  162 , which is detected or measured by the LVDT  134 . At any float position other than the rest position, the weight and buoyancy forces are balanced by the fluid pressure acting on the cross-sectional area of the float  142  or drag force, and spring force, if applicable. The continuity equation mentioned above applies to all float positions; that is, the mass or volume flow “in” must equal the mass or volume flow “out”. In other words, flowrate IN=flowrate OUT. 
     A separate display and electronic enclosure  180  can be remotely secured or coupled to the flow control manifold  106 . The electronic enclosure  180  can include a housing, with a signal conditioner circuit board  184  and a main controller and driver circuit board  186  housed therein. An operator interface and display  188  can also be integrated into the housing, and possibly mounted on a tiltable panel. 
     The manifolds  105  and  106  are illustrated as being embodied in separate units or housings, but these manifolds  105  and  106  can be combined into a single housing. In the embodiment illustrated in  FIGS. 2 and 3 , the manifolds  105  and  106  are separate, and an O-ring  196  can be provided at the connection between the manifolds  105  and  106  to provide an effective fluid seal. One aspect of the present invention is that the various components (manifolds  104 ,  105  and  106 , and display and electronic enclosure  180 ) can be provided in separate modules and then assembled together on a modular basis. The modularity of these components allows the end user to have options to use differently-sized or differently-calibrated components with different applications. 
     A number of applications lend themselves to be used by the present invention. For example, the flow control valve assembly  100  is effective in controlling output flowrate to meet the requirements of any given application, such as controlling the velocity or speed of an actuator. Other examples include use to:
         limit output flowrate for a specific channel (e.g., controlling chilled or heated fluid flowrate for precision heating or cooling);   limit output flowrate for multiple channels (e.g., for flow distributions which are comparable to an electrical distribution panel);   split or divide an inlet flow to meet a specific flow ratio requirement (e.g., gas engine application); or   combine multiple inlet flow channels into one for accurate mixing (e.g., precision chemical fluid mixings).       

     The flow control valve assembly  100  is illustrated herein as being mounted vertically during use (e.g., see  FIGS. 1A, 1B and 1C ), but it can also be mounted horizontally. The difference between the two orientations is that the extension rod spring  150  is optional with the vertical orientation, but the spring  150  would be required if the assembly  100  is mounted horizontally. 
     The above detailed description is for the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims. In certain instances, detailed descriptions of well-known devices, components, mechanisms and methods are omitted so as to not obscure the description of the present invention with unnecessary detail.