Abstract:
A fluid metering or pumping device includes multiple pumping or metering elements that are connected so that they all operate together, moving in the same direction and at the same speed. The multiple pumping or metering elements are intended for use at high pressures where the strain from the pressure might distort the walls of the elements, and interfere with their pumping or metering accuracy. These elements are enclosed in, but preferably not directly connected to a pressure vessel that would contain the high operating pressure, leaving the pumping or metering element housings to only contain the pressure rise or fall that occurs within that element. The pumping or metering elements are connected to a support structure that also penetrates the pressure vessel, and contains an outlet port for that element. The pressure vessel connects the elements, and serves as an intake plenum for all of the elements.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/048,798, filed on Apr. 29, 2008 entitled FLOW DIVIDER whose entire disclosure is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates generally to devices for regulating the flow of liquids, and particularly relates to a flow divider for dividing a stream of liquid, such as liquid fuel, into two or more smaller streams of liquid or to a pump for pumping a single flow of liquid to one or more locations in substantially accurate flow rates. 
     2. Description of Related Art 
     When working with liquids, it is often desirable to divide a single stream of liquid into several smaller, preferably equal streams of liquid or several substantially accurate streams of liquid. This is typically done using a fluid metering device such as liquid flow divider, an equal-flow pump, or an equal-flow liquid motor. 
     A typical prior art liquid flow divider is taught in U.S. Pat. No. 4,531,535 to Kiernan. As shown in FIG. 4 of Kiernan, such liquid flow dividers typically include multiple dividing units of two intermeshed spur gears. The various dividing units are typically linked together by a drive train that may include a drive line, drive shafts, or a sun gear. As a result of this linkage, all of the gears within the various dividing units rotate at substantially the same speed. 
     Within each individual dividing unit, a liquid inlet port is positioned on one side of the intermeshing portion of the pair of spur gears, and a liquid discharge port is positioned on the other side of the intermeshing portion of the pair of spur gears. A housing is provided that conforms to the exterior portions of the spur gears that are not in communication with the liquid inlet port or the liquid discharge port. All of the various dividing units&#39; liquid inlet ports are in communication with a single, pressurized liquid source. 
     In operation, pressurized liquid from the pressurized liquid source first enters each dividing unit&#39;s liquid inlet port. The pressurized liquid then causes the gears in each dividing unit to rotate in opposite directions so that each gear&#39;s teeth carry liquid from the liquid inlet port, around the exterior portion of the gear, and into the liquid discharge port. Because all of the dividing gears within the liquid flow divider are preferably the same size and shape, and because the gears are linked together by a central drive train so that all of the gears rotate at the same rate, the flow rate of liquid around each of the flow divider&#39;s various gears is identical to the flow rate of liquid around each of the flow divider&#39;s other gears. Accordingly, because each dividing unit contains two gears of substantially the same size that convey liquid from the dividing unit&#39;s liquid inlet port to the dividing unit&#39;s liquid discharge port, liquid flows through each dividing unit at a rate that is equal to two times the rate at which the liquid flows around a single gear. 
     Accordingly, prior art liquid flow dividers are typically designed to include one dividing unit for each equal discharge stream that the flow divider is to produce. For example, if the flow divider is to produce 10 equal discharge streams of liquid, the flow divider will include 10 separate dividing units. The liquid fuel entering the flow divider normally enters at an elevated pressure relative to ambient conditions. Then it exits the flow divider normally at a discharge line pressures that are lower than the inlet pressure since energy is lost in making the gears rotate. This elevated pressure inside the flow divider exerts forces on the housings of the dividing units that are proportional to the difference between the pressure inside the flow divider and ambient pressure outside the flow divider. This force on the housing can, when the difference in pressure is high enough, cause the housings to expand, change shape, and deform, and detrimentally affect the diving units&#39; metering efficiency or impair their rotation. 
     Flow dividers have been developed that did away with this deformation of the dividing units by enclosing them inside a pressurized plenum. The pressure plenum would contain the high pressure of the fuel, and be subjected to the large forces resulting from the difference between the liquid pressure inside the flow divider and ambient atmospheric pressure outside. The dividing units themselves would be subjected to only the much smaller pressure differences generated by the liquid passing through them. This type of flow divider, usually denoted a “circular flow divider”, has the dividing units arranged in a circular array around a central timing gear or sun gear. This timing gear intermeshes with the innermost gears in all dividing units to synchronize and cause all dividing units to always rotate at the equal speeds. A large, circular housing or plenum contains all of these dividing units and functions as a pressure vessel. The liquid fuel enters the flow divider through a port or ports in this circular housing and fills its volume so as to submerge the dividing units. The pressurized liquid fuel is forced into each dividing unit through an inlet port hole in each one. 
     U.S. Pat. No. 6,857,441 to Flavelle (“Flavelle”) solved some problem of the earlier art by providing a pressure balance inlet port and a pressure balance discharge port adjacent an exterior portion of each end gear within a series of gears for balancing forces exerted on the end gear by liquid passing through the various inlet and discharge ports. However, there continues a need for improved liquid flow dividers, and other fluid metering devices, that are more robust and that take up less space than prior art fluid metering devices. 
     All references cited herein are incorporated herein by reference in their entireties. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with an example of the preferred embodiments, the invention includes a flow divider having a plenum as a pressure containing vessel, a plurality of dividing units housed within and distinct from the plenum, a connecting shaft, and a support structure coupled to the plenum. Each dividing unit includes a plurality of intermeshed driving gears and is aligned with another one of the dividing units so that the driving gears of the respective dividing units are coaxial. The connecting shaft mechanically connects the driving gears of one of the dividing units with the driving gears of an aligned dividing unit to form adjoining driving units. The driving gears of both of the adjoining dividing units are connected by the connecting shaft to rotate at the same speed. The dividing units have an outlet port in fluid communication with one of the dividing units. 
     In accordance with another example of the preferred embodiments, the flow divider includes a plurality of dividing units containing intermeshing driving gears, with the dividing units arranged so the intermeshing driving gears are coaxial and so that they all rotate together. The flow divider also includes a pressure containing vessel that surrounds, but is separate from, that is, not part of, the dividing units. The pressure containing vessel forms an inlet plenum conducting liquid to all of the dividing units simultaneously. In addition, the flow divider includes a support structure that secures each dividing unit and contains individual outlet ports for each dividing unit surrounded by the pressure containing vessel. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE-DRAWINGS 
       The invention will be described in conjunction with the following drawings in which like reference numerals designate like elements and wherein: 
         FIG. 1  is an exploded view of a flow divider in accordance with an exemplary embodiment; 
         FIG. 2  is a partial view of an exemplary dividing unit; 
         FIG. 3  is a partial view of a flow divider in accordance with another exemplary embodiment; and 
         FIG. 4  is a partially sectional view of the dividing unit shown in  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The preferred embodiments of the invention provide a more economical means of producing the pressure plenum flow divider by orienting and mechanically linking the dividing units in linear fashion, eliminating the large timing gear or sun gear, reducing the overall diameter, and separating the pressure vessel function from the dividing units themselves.  FIG. 1  depicts an exemplary flow divider  10 . As can be seen in  FIG. 1 , the flow divider  10  includes a plurality of dividing units  12  as flow elements mounted onto one of a plurality of support structures  14 ,  16 ,  18 . 
     Each support structure  14 ,  16 ,  18  is preferably a metal and/or alloy disk having apertures and passages within for fluid communication as discussed, for example, in greater detail below. In particular, each support structure includes an internal passage  20  ( FIG. 4 ) leading from the discharge of each dividing unit through the support structure to a port  22  on the peripheral edge of each support structure. While not being limited to a particular theory, the support structures each include a number of outlet ports  22  corresponding to a number of dividing units coupled to the support structure, with each port dedicated to the output of a respective one of the coupled dividing units. According, the support structure  14  has eight ports  22  for its attached eight dividing units  12 , while the support structures  16  and  18  each have four ports  22  for their respectively attached four dividing units. 
     Still referring to  FIG. 1 , passages (e.g., conduits) through the dividing units  12  and the support structure  14 , 16 , 18  allow incoming liquid to pass through a plenum input port  44  and fill the plenum volumes within tubular rings  24 ,  26  on both sides of the support structures, as described in greater detail below. For purposes of clarity, the support structure  14  will also be referred to as the center support structure, the support structure  16  will also be referred to as the proximal support structure, and the support structure  18  will also be referred to as the distal support structure. 
     A first tubular pressure containing ring  24  connects to and seals against the support structures  14  and  16 . Likewise, a second tubular pressure containing ring  26  connects to a seals against the support structures  14  and  18 . A connecting shaft  28  runs through the tubular ring  24  and mechanically connects intermeshed driving gears  52 ,  54  within the two dividing units  12  so the connected dividing units rotate at the same speed. This layout of connecting shafts  28  to aligned opposing dividing units  12  is repeated until the flow divider  10  contains the desired quantity of dividing units. The dividing units  12  and support structures  14 ,  16 ,  18  further include passages, that along with the open volumes inside the tubular pressure rings  24 ,  26 , create a continuous inlet plenum for communicating fuel to all of the flow elements simultaneously. Of course, the at least one of the tubular pressure containing ring, here pressure ring  26  also includes a plenum input port  44  for receiving the fluid, as readily understood by a skilled artisan. 
     A gear unit  30  includes a small driving gear  32  coupled to a connecting shaft  28  that connects to a first split gear  34  of a split gear unit  36 . The first split gear  34  is linked to second, third and fourth split gears  38  by a positive drive mechanical linkage unit  40  (e.g., chain, timing belt, spur, tooth gear). Each of the split gears is coupled to a respective connecting shaft  28 . The connecting shafts extend through aligned apertures  42  of the support structure  16  and mechanically link the split gears  34 ,  38  to the respective dividing unit  12  on the opposite side of the support structure. The connecting shafts  28  therefore orient and mechanically link the dividing units  12  in linear fashion, while eliminating the large sun gear found in known flow dividers. The arrangement of four lines of dividing units reduces overall diameter. Moreover, the tubular rings separate the pressure vessel function from the dividing units themselves. It is understood that the gear unit  30  is one example of an apparatus for controlling or equalizing the rotational speed and direction of the dividing units within the flow divider, and that the invention is not limited to any one configuration. 
     It should be noted that the number of dividing units mounted to each support structure is not limited. Also, dividing units may be mounted on one or both sides of the support structures, as shown, for example by the dividing units  12  mounted on both sides of the support structure  14 , and on only one side of the support structure  16  and  18 . The actual number of dividing units and their locations can be chosen to obtain the required number of discharges in the smallest package. When only one dividing unit  12  is attached to a side of a support structure, it can be mounted so the rotational axis of the driving gear coincides with the center of the support structure. Doing so eliminates the need to accurately align the support structures rotationally to one another to prevent binding of the interconnecting drive shafts. 
       FIGS. 2 and 4  depict a cutaway view and a partial sectional view, respectively, of an exemplary dividing unit  12  mounted to a support structure  14 . The dividing unit  12  includes a housing  46  and rotating intermeshed gears  52 ,  54  within the housing. The dividing unit  12  may also include bearings  66  adjacent and axially aligned with the intermeshed gears  52 ,  54  that attach to respective connecting shafts  28 . A inlet port  50  shown as a round passageway running through the dividing unit where the two rotating intermeshed gears  52 ,  54  diverge, that is, come out of mesh. The support structure  14  includes an aperture  56  that lines up with the inlet port  50  and connects with a similar round passageway through the dividing unit mounted to the opposite (distal) side of the support structure. As can best be seen in  FIG. 4 , on the far (right) interior facing side of the dividing unit  12 , where the rotating gears come into mesh (e.g., converge), is a discharge passageway  64  that runs only through the back of the dividing unit, as readily understood by a skilled artisan. The discharge passageway  64  communicates with the aligned internal passage  20  in the support structure  14  that extends to port  60 . In like manner, the discharge passageway  64  of the dividing unit  12  connected to the far side of the support structure communicates with another internal passage  20  of the support structure  14  that extends to port  62 . That is, the internal passages  20  communicate fluid from the discharge passageways  64  of the coupled dividing units  12  to respective output ports  60 ,  62 ,  22 . 
     Another example of the preferred embodiments is depicted in  FIG. 3 , with arrows showing exemplary fluid flow. The flow divider illustrated in  FIG. 3  includes the same dividing units, laid out in substantially the same linear fashion, and mechanically connect together to rotate at the same speeds in the same way. However, in this example, the pressure plenum flow divider  70  is a rectangular box shape instead of generally cylindrically shaped as the flow divider  10 . The flow divider  70  includes a plenum  68  or pressure vessel that houses a plurality of dividing units  72 , with some of the dividing units coupled to another dividing unit on one side, and/or to a support structure  74 . For example, while not being limited to a particular theory or quantity, the flow divider  70  contains three support structures  74 , with each support structure coupled to either one or two dividing units  72 . The dividing units  72  are adjoined to other dividing units via connecting shafts  76  that mechanically and coaxially connect the driving gears within the adjoining dividing units  72  so the adjoined dividing units rotate at the same speed. 
     Of course it is understood that the preferred embodiments are not limited to a maximum of two adjoining dividing units  72  per support structure  74 , as any number of adjoining dividing units are applicable within the scope of the invention. It should also be noted that the dividing units  72  and supporting structure  74  are substantially the same in structure and function as the dividing units  12  and supporting structures  14 ,  16 , and  18 , respectively, as discussed above even though the dividing units and supporting structures have different shapes. In other words, the structural elements of the flow dividers (e.g., dividing units, support structure, plenum, ports, passages, shafts) are not limited to the shape of the elements as shown by example herein. 
     Still referring to  FIG. 3 , each support structure  74  is attached to the plenum  68 , and includes an interior passage within the structure. The passage in each support structure  74  provides liquid communication between the output port of the respectively coupled dividing unit  72  and a respective interior conduit  78  within the plenum, for providing fluid from the dividing unit to an output port  80  of the conduit. Accordingly the plenum  68  includes three output ports, one for each support structure  74 . Of course, the plenum  68  also includes an input port  82  for receiving the fluid, as readily understood by a skilled artisan. 
     In operation, pressurized liquid from the pressurized liquid source first enters the plenum that contains the dividing units and functions as a pressure vessel. The liquid fuel enters the plenum input port  82  and fills the pressure vessel&#39;s volume so as to submerge the contained dividing units  72 . The pressurized liquid fuel is forced into each exposed dividing unit through a respective inlet port  84 . The dividing units  72  are subjected to only the much smaller pressure differences generated by the liquid passing through them, and pass the liquid to the support structures  74 . The interior passage of the support structure passes the liquid to the conduits  78  of the plenum  68 . The liquid then exits the flow divider  70  preferably at discharge line pressures via the output ports  80  of the plenum. 
     It is understood that the flow dividers  10  and  70 , and the components and elements thereof are made of metal and/or alloy as preferred to withstand the forces and pressures exerted by and applied to the elements by mechanical and fluid force, as is readily understood by a skilled artisan. 
     Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only, and not for purposes of limitation.