Abstract:
A rotary positive displacement flowmeter of the type utilizing two displacement rotors and a blocking rotor with the blocking rotor having a single recess and the displacement rotor cylinders being of substantially similar size as the blocking rotor, resulting in a uniform flowpath through the flowmeter with alignment of the rotor axes in a 180 degree plane.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to flowmeters, and more particular to rotary positive displacement flowmeters utilizing multiple displacement rotors and a blocking rotor. 
       BACKGROUND OF THE INVENTION 
       [0002]    Positive displacement flowmeter are well known in the art. Specifically, such a device is used in various applications within widespread industries, including the petrochemical and natural gas industries. The general purpose of a flowmeter is to measure the quantity of a substance, typically a gas or a liquid, flowing through the meter such that the amount of the substance can be readily and accurately determined. 
         [0003]    Typically, a substance flows through a conduit or line designed to move the substance from one point to another. Where applicable, the conduit is separated and a flowmeter is attached and, in many instances, the entire flow path of the substance is then diverted through the flowmeter. The movement of the substance through the flowmeter causes the meter contained within the flowmeter apparatus to measure and/or record the quantity of substance moving through the flowmeter. 
         [0004]    Given the typical application of a flowmeter, accuracy, flow volume and energy efficiency are important. It is desirable for the flowmeter to be accurate and measure precisely the amount of substance moving through the meter. In industrial settings, it is also desirable for the flowmeter to be able to accommodate an increased flow rate to maximize production and/or operations without jeopardizing the integrity and/or accuracy of the flowmeter. 
         [0005]    The flow rate of the substance impacts factors that contribute to the longevity of a flowmeter, specifically pressure drop, cyclical pressure drop fluctuation and vibration. Over time these factors can damage the flowmeter thus decreasing both the accuracy of the meter and its longevity. When a flowmeter is damaged or ceases to work properly, the flow of the substance either has to be stopped or diverted so that the flowmeter can be detached from the conduit segments and a new flowmeter attached. Such downtime can significantly disrupt industrial operations. 
         [0006]    Pressure drop and vibration generally increase with flow rate. Therefore, the structural design of the flowmeter, in as much as the design contributes to the degree of pressure drop and vibration, imposes a maximum flow rate on a flow meter above which accuracy and longevity is compromised. At a certain level of pressure fluctuation or vibration intensity, mechanical stresses will distort or flex the shapes of the rotors and/or the housing enough to allow unmetered flow, i.e. slippage, between the rotors and/or between the rotor and the housing, and/or cause physical damage to the bearing and other meter components, all directly impacting the accuracy and longevity of the meter. 
         [0007]    A number of sources contribute to the pressure drop and vibration of a flowmeter as currently available in the art. First, in general, a flow path that is straight is only impeded by the friction exerted by the walls of the conduit and can move fluidly. However, as angles or turns are introduced into the path, which is typical in such applications, extra work is required to overcome inertia and the substance is met with increased friction at such angles or turns requiring greater energy to drive the device. The degree to which the flow of the substance is impacted or influenced depends on the degree of the angle or turn. The greater the degree of the turn, the greater the resistance. 
         [0008]    The same principle is applicable for the flowmeter and the flow of substance through the flowmeter. A flowmeter that creates, by virtue of its structure, more turns and angles of the flow path will have greater pressure drop compared to a flowmeter with less turns and angles, other factors being equal. It is therefore desirable to have a flowmeter that creates a smooth, fluid flow path that minimizes turns and angles. 
         [0009]    The second factor is the blocking rotors which impact flow in two ways, namely by virtue of both placement and design. In existing art designs, the blocking rotor is placed between the inlet and outlet in such a manner that the blocking rotor itself obstructs the inlet and outlet ports. The location of the blocking rotor within the flow path obstructing the flow generates cyclical vibrations that are undesirable. Therefore, it is desirable to position the blocking rotor such that it minimizes interference with the flow path. 
         [0010]    Positioning the blocking rotor more directly between the displacement rotors decreases the interference with the inlet and outlet flows by the blocking rotor, a common problem existing in the art. It is desirable to increase the displacement rotor hub radius to substantially the same size as the blocking rotor radius to uniformly align the blocking rotor between the displacement rotors, reducing and/or eliminating the extent to which the blocking rotor interferes with the flow path. In a given housing size, the larger displacement rotor hub means shorter displacement rotor blades. In prior art, displacement rotor blade length was maximized to make the flow path as wide as possible in a given housing size. However, it is desirable to back away from maximum displacement rotor blade length in favor of reduced blocking rotor interference in the flow path, less turbulence inside and outside of the blocking rotor and improved efficiency. This is a trade off not seen in the prior art. The displacement rotor blades in prior models by Kolb and Richards extend to nearly the center of the blocking rotor, where the preferred embodiment displacement rotor blades reach less than half way to the center of the blocking rotor center, thus generating less turbulence inside the blocking rotor. 
         [0011]    Regarding the blocking rotor design, current blocking rotors in the art have multiple recesses or cavities. The use of multiple cavities requires the blocking rotor structure to have a web(s) or wall(s) between the cavities. During the rotation of the blocking rotors, the flow confronts these walls which generate turbulence and vibrations in the meter. 
         [0012]    Blocking rotors known in the art teach away from having a single cavity blocking rotor, as discussed in more detail later. However, a single cavity blocking rotor reduces the turbulence and vibrations in the meter by eliminating the rotating interior web surface which reduces turbulence, and reduces the work required to rotate the blocking rotor, and makes the flow path more stable with decreased points of fluctuation in flow from structural events. Therefore, it is desirable to maximize the efficiency of the blocking rotor by having only one cavity. 
         [0013]    A third factor is that some displacement rotors are not balanced around their axis of rotation. This contributes to additional vibration and damage to the flowmeter. It is desirable to have balanced displacement rotors to minimize vibration. 
         [0014]    All four of the sources described above, as well as others, contribute to the negative effects associated with increased flow rate such that a maximum useful flow rate is intrinsically imposed on the flowmeter simply by virtue of its design. These limitations within the current state of the art are founded on a series of technologies in the art beginning with George Richards&#39; U.S. Pat. No. 2,835,229 in 1958. 
         [0015]    The first embodiment of Richard&#39;s flow meter invention is the version built around a cylindrical blocking rotor with two recesses as show in FIGS. 1 through 10 of the 1958 patent. This version has been the model for most, if not all, of the flowmeters built since then within this type of flowmeter design. The design of the blocking rotor with two recesses used by Richards significantly obstructs the inlet and outlet ports, as evidenced by later patents, including Siebold&#39;s 1969 U.S. Pat. No. 3,457,835, Blomgren&#39;s 1969 U.S. Pat. No. 3,465,683 and Kolb&#39;s 1978 U.S. Pat. No. 4,109,525. 
         [0016]    Additional attempts were made to try to remedy the problem of the blocking rotor. Kolb&#39;s 1996 U.S. Pat. No. 5,513,529 improves the design of the flowmeter by redirecting the inlet and outlet ports toward the displacement rotors and less toward the blocking rotors than in prior designs, but the historical trefoil configuration of the rotors still positions the blocking rotor to partially block the flow through the inlet and outlet, as seen in FIG. 1 of the Kolb 1996 patent. 
         [0017]    Kolb&#39;s 1998 U.S. Pat. No. 5,808,196, made further modifications to the inlet and outlet ports, as well as an extension of the upper housing further down to shield the blocking rotor from direct inlet and outlet flow and to reduce vibrations. However, large turns in the flow path are still inherently required by the position of the blocking rotor relative to the inlet and outlet. Instead of the blocking rotor obstructing the flow path, that portion of the housing which shields the top of the blocking rotor now directly obstructs the inlet and outlet. 
         [0018]    The Kolb 1998 patent also features a displacement rotor blade which during part of its rotation cycle, extends across the adjacent blocking rotor cavity almost to contact the central wall dividing the two blocking rotor cavities. In its rotation the displacement rotor blade must forcefully intrude, displacing and sweeping through the volume of fluid within the blocking rotor cavity. This action generates turbulence, uses increased energy and contributes to the pressure drop and to cyclical pressure drop fluctuations responsible for some of the remaining vibration in flow meters currently available in this design. 
         [0019]    While attempts have been made to remedy the problem associated with the impact of the flow path and flow rate by the structure and components of the flowmeter, the use of a single cavity blocking rotor has not been used in the art. In Richards&#39; 1958 patent, Richards uses a variety of algebraic formulas to describe the numerical relationships between the integral and geometric parameters shaping the elements in the various forms of his invention. These equations describe the angles between rotor axes and the angular extent of various arcuate surfaces all ultimately as function of two integral variables, B and D, where B is the number of recesses in the blocking rotor and D is the number of displacement rotors. Notably, Richards, as well as Kolb, all feature blocking rotors only with two or more recesses (B&gt;=2). No one in the prior art has developed a single cavity blocking rotor (B=1) due to the fact that the prior art teaches away from a single cavity blocking rotor because the algebraic and geometric principles upon which the Richards and Kolb flowmeters were designed and configured preclude the very use of a single cavity blocking rotor. 
         [0020]    In order to create a flowmeter with a single cavity blocking rotor, the long standing principles and formulas of Richards had to be contradicted for a new formula that incorporates structural changes to both the blocking rotor and the displacement rotors to permit a single cavity blocking rotor. The simpler and more efficient blocking rotor in the preferred embodiment is not possible applying Richards&#39; principles and formulas. 
         [0021]    In particular, Richards&#39; principle (6) in his 1958 patent text column 9, lines 34-39 requires “the angular extent (β) of each sealing surface of the blocking rotor be equal to 360 degrees divided by the product of the number of recesses in the blocking rotor (B) and the number of displacement rotors (D).” Richards, and subsequent flowmeters modeled using his equations and principles, set (B) equal to or greater than 2. A double recess blocking rotor would require the angular extent (β) of the sealing surface on the blocking rotor to equal 360 degrees divided by 4, or 90 degrees. About 90 degrees is the largest blocking rotor sealing surface angular extent seen in the prior art. 
         [0022]    Unlike any of Richards&#39; embodiments&#39; or any related prior art, the preferred embodiment of this new invention exhibits only one recess in the blocking rotor (B=1). Taking the single cavity blocking rotor (B=1) and two displacement rotors (D=2) and applying Richard&#39;s equations results in an angular extent (β) of the sealing surface on the blocking rotor to equal 360 degrees divided by 2, or 180 degrees, and the angular extent of the blocking rotor recess to also equal 180 degrees. Since these two angular components entirely describe the blocking rotor&#39;s circular cross-section, such a blocking rotor would render the flowmeter useless since it would fail to provide a continual sealing surface between the blocking rotor, the displacement rotors and the interior surface of the chamber, or else physically interfere with the displacement rotor blades. 
         [0023]    In the preferred embodiment, the angular extent of the blocking rotor sealing surface is around 300 degrees with one recess, an embodiment that is not possible with Richards&#39; principle (6). This new approach to flowmeter technology permits a unique blocking rotor and casing design that are far outside the parameters allowed by Richards&#39; formula. Only by contradicting the longstanding principles and equations of Richards and the subsequent developed technology based upon his science is the single cavity blocking rotor possible. 
         [0024]    Next, Richard&#39;s principle (8) (in his 1958 patent text column 9, lines 49-52) requires the angular extent (φ) of the surface on the casing making sealing contact with the blocking rotor to be &gt;=Δ, in this case &gt;=180 degrees. However, Principle (5) (in his 1958 patent text column 9, lines 34-40) requires the angle between the axes of the two displacement rotors to equal 360 degrees divided by the number of recesses (B) in the blocking rotor less the angular extent (β) of the sealing surface of the blocking rotor, or 360/1−180 degrees=180 degrees. Thus for this design configuration, Richards&#39; principle (5) also places the axes of the two displacement rotors 180 degrees apart, requiring the displacement rotor hubs to meet the blocking rotor in exactly the same physical space in which the sealing surface of the casing also would meet the blocking rotor. 
         [0025]    This would necessarily locate the physical material of the casing simultaneously in the same volume of space where the sealing surfaces of at least one displacement rotor hub must meet the sealing surface of the blocking rotor, a physical impossibility, which if it were somehow made possible—say with a casing of nearly zero thickness—would still fatally interfere with full rotation of the displacement rotor blades. 
         [0026]    Under Richard&#39;s equations, designs with a single cavity blocking rotor and more than two displacement rotors (B=1 and D&gt;2) fail for the same reason. Richards&#39; equations result in unworkable interference between the casing and one or more of the displacement rotors in all such cases. 
         [0027]    In the preferred embodiment the angle between the axes of the two displacement rotors is 180 degrees. However, choosing parameters far outside the bounds of Richards&#39; principle (6) in the preferred embodiment, the angular extent of the blocking rotor sealing surfaces is about 300 degrees, much greater than the prescribed 180 degrees. This shrinks the angular extent of the blocking rotor recess down from 180 degrees to about 60 degrees instead. Correspondingly, the angular extent of the casing surface which seals with the blocking rotor then is also shrunk down to about 60 degrees, positioning said casing well outside of each displacement rotor blade&#39;s path of rotation. 
         [0028]      FIGS. 6 ,  7 ,  8 , and  9  show a range of designs where the angular extent of the blocking rotor sealing surfaces ranges between 210 and 300 degrees, illustrating alternative embodiments of this invention. These ranges are not to be construed as limiting. Angular value parameter choices anywhere within this continuous range, and somewhat beyond it at either end, are feasible under the new principles. This is unlike Richards&#39; claims which specifically limit this angle to 360 degree/BD, where B and D must be small integers, i.e., B=the number of recesses in the blocking rotor and D=the number of displacement rotors. 
         [0029]    Another key difference between more recent prior art blocking rotors and the preferred embodiment is that instead of Kolb&#39;s (1998 patent) circular end walls recessed into circular depressions machined into the housing end plates, the preferred blocking rotor end walls are circular minus just enough of a cutout to allow for cooperation between the rotation of the displacement rotor blades and the blocking rotor end wall without necessarily recessing the blocking rotor end wall into impressions in the end plate, simplifying their manufacture. 
         [0030]    End wall to end wall, Kolb&#39;s blocking rotor is axially longer than his displacement rotors, while the preferred blocking rotors are the same length as the preferred displacement rotors. Circular end walls with a small cutout maintain most of the extra strength and rigidity provided by Kolb&#39;s light weight blocking rotor with end walls, while also allowing simpler flat end plates, i.e., no need to machine circular recessions/depressions for the blocking rotor, thus allowing each end plate to be simpler to manufacture by virtue of its working surface being flat in a single plane. The preferred embodiment still allows recessing the blocking rotor into the housing end plate if desired for other reasons. 
         [0031]    Prior art used a 90 degree angle between the three rotor axes, necessarily positioning the blocking rotor so as to define and require a flow path in which the blocking rotor and/or the blocking rotor sealing surface of the casing is necessarily located where it must force sharp turns in the flow path at both the inlet and outlet and also directly obstructing flow and forcing a sharp turn below the blocking rotor, between the two displacement chambers, contributing to the pressure drop. 
         [0032]    It is therefore desirable to have a flowmeter with a flow path that can accommodate an increased flow rate but has decreased pressure drop, cyclical pressure drop fluctuation and vibration. 
         [0033]    It is further desirable to have a flowmeter that can maintain accuracy despite increased flow rates due to a smoother and more fluid flow path through the meter. 
         [0034]    It is further desirable to have a flowmeter with a compact housing with in-line inlet and outlet ports for universal replacement of other compact in-line flowmeters of competing and less accurate varieties. 
         [0035]    It is further desirable to have a flowmeter with easy in-line replacement installation in tight locations where flowmeters needing the added length of custom runners would be ruled out. 
         [0036]    It is further desirable to have a flowmeter with high maximum flow rates exceeding similarly sized prior models. 
         [0037]    It is further desirable to have a flowmeter with accuracy over a range of flow rates exceeding the current state of the art for positive displacement flowmeters. 
       SUMMARY OF THE INVENTION 
       [0038]    This invention resides in an improvement of a rotary positive displacement flowmeter device of the type having a housing within which a pair of displacement rotors are rotatably mounted within a fluid chamber, and a blocking rotor positioned between the displacement rotors. 
         [0039]    The invention resides in the use of a cross over inlet and outlet configuration, which may be bifurcated at the inlet or outlet, to allow a smoother flow path with less angles and turns to decrease the turbulence, vibration and pressure drop within the system. 
         [0040]    The structure of the cross-over feature diminishes the need for custom runners in many cases and allows application of this flowmeter to existing installations where other flowmeters would not fit. The cross-over feature also permits a smoother flow into the flowmeter chamber compared to currently existing designs where the flow must abruptly turn 90 degrees or more into the flowmeter, resulting in greater turbulence, pressure drop and vibration. 
         [0041]    The invention resides in an additionally improved blocking rotor having a single opening, cavity or recess, applicable to both cylindrically solid and hollow rotor embodiments. Having one recess instead of 2 or more allows the blocking rotor to be located more directly between the displacement rotors, reducing its obstruction of both the inlet and outlet chambers, as well as decrease the overall area of blocking rotor surfaces confronting and opposing fluid flow during the blocking rotor&#39;s cyclical rotation improving the consistency of the flow rate through the flowmeter resulting in decreased pressure drop, turbulence and vibrations. 
         [0042]    The blocking rotor, in the preferred embodiment, is a hollow chamber which can be rotated with much less work than any blocking rotor in the prior art, also generating less turbulence. 
         [0043]    For the most accurate measurement of fluid transfer, ideally the meter casing would be completely filled with fluid at all times, including the volume inside the preferred hollow cylindrical blocking rotor. Unlike prior art blocking rotors, the single cavity requires no bisecting web surface and therefore does not waste energy rotating fluid inside the rotor. This greatly reduces flow resistance, rotational inertia, and energy wasting turbulence inside and around the blocking rotor. Energy loss due to rotation of the single cavity blocking rotor is a fraction of that loss for two or more cavity prior art blocking rotors. This means a lower pressure drop across the device and a more linear measurement response at lower flow rates than is possible for blocking rotors with more than one recess separated by webbed surfaces. Lower pressure drop means a smaller flow meter might be made to serve the given application, or a smaller pump and less energy used to drive it. 
         [0044]    The single cavity blocking rotor also allows the more efficient 180 degrees straight-line design configuration of the three rotors which is not allowed by the two cavity blocking rotor in Richards&#39; preferred trefoil shaped embodiment. Prior art trefoil configurations inefficiently direct the flow toward the blocking rotor and/or the blocking rotor sealing surface of the casing forcing sharp turns in flow at the inlet and at the outlet. They also direct flow toward the blocking rotor forcing another turn below the blocking rotor between the two displacement chambers. All of these turns create turbulence, waste energy, and contribute to pressure drop across prior art devices. The degree of blocking rotor obstruction at each of these turns varies cyclically with its rotation, thereby contributing to increasing vibration at higher flow rates. 
         [0045]    The straight-line arrangement of the rotors more efficiently directs the flow path around the blocking rotor, not toward it. Much lower energy cost, lower pressure drop, and less vibration is generated by this invention because the straight line rotor axes configuration does not direct flow toward the blocking rotor at the inlet, nor at the outlet, nor between the displacement chambers. This more efficient flow path with fewer obstructions and fewer sharp turns may allow smaller devices to be constructed with the same flow capacity of larger prior art devices. That combined with its simplicity of design suggest this invention may offer significant cost advantages over comparable devices in a wide range of installations. 
         [0046]    The invention resides in displacement rotors with a more prominent hub compared to any available in the art, with a radius large enough to route the flow completely around the blocking rotor, reducing its interference with the flow. Displacement rotor hubs performing this function are not found in prior art. The displacement rotor hub, in the preferred embodiment, defines a hollow chamber bisected by the displacement rotor blade. Unlike prior are, the preferred displacement rotor hub radius is about equal to the blocking rotor radius, allowing the displacement rotor hub surface and the blocking rotor surface to roll against each other with equal velocities, reducing fluid shear and slippage between the rotors for improved accuracy. The displacement rotor blade extends beyond the hub circumference to the extent necessary to create a sealing means with both the blocking rotor recess and the interior wall of the housing, more particularly, the fluid chamber. 
         [0047]    The invention resides in the configuration of the inlet and outlet chambers, the fluid chamber, the blocking rotor and the displacement rotors, in creating a flow path that is smoother, straighter and less turbulent flow path, than is previously known in the art which results in greater accuracy at higher flow rates, as well as to increase the longevity of the meter at increased flow rates. 
         [0048]    The foregoing and other objects are intended to be illustrative of the invention and are not meant in a limiting sense. Many possible embodiments of the invention may be made and will be readily evident upon a study of the following specification and accompanying drawings comprising a part thereof. Various features and subcombinations of the invention may be employed without reference to other features and subcombinations. Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, an embodiment of this invention. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0049]    Preferred embodiments of the invention, illustrative of the best modes in which the applicant has contemplated applying the principles, are set forth in the following description and are shown in the drawings and are particularly and distinctly pointed out and set forth in the appended claims. 
           [0050]      FIG. 1A  is a cross section of an embodiment of a positive displacement flowmeter. 
           [0051]      FIG. 1B  is a cross section of an embodiment of a positive displacement flowmeter. 
           [0052]      FIG. 1C  is a cross section of an embodiment of a positive displacement flowmeter. 
           [0053]      FIG. 1D  is a cross section of an embodiment of a positive displacement flowmeter. 
           [0054]      FIG. 2  is a bottom and side view of an embodiment of a positive displacement flowmeter housing. 
           [0055]      FIG. 3  is an exploded view of a meter. 
           [0056]      FIG. 4  is an angled view of a blocking rotor. 
           [0057]      FIG. 5  is an angled view of a displacement rotor. 
           [0058]      FIG. 6  is a cross section of an embodiment of a positive displacement flowmeter showing alternative angular relation between the axes of the displacement rotors and the axis of the blocking rotor. 
           [0059]      FIG. 7  is a cross section of an embodiment of a positive displacement flowmeter showing alternative angular relation between the axes of the displacement rotors and the axis of the blocking rotor. 
           [0060]      FIG. 8  is a cross section of an embodiment of a positive displacement flowmeter showing alternative angular relation between the axes of the displacement rotors and the axis of the blocking rotor. 
           [0061]      FIG. 9  is a cross section of an embodiment of a positive displacement flowmeter with an alternative housing structure for the attachment. 
           [0062]      FIG. 10  is a top, cross section of an embodiment of a positive displacement flowmeter demonstrating a bifurcated inlet chamber. 
           [0063]      FIG. 11  is a top, cross section of an embodiment of a positive displacement flowmeter showing a cross over inlet and outlet chamber. 
           [0064]      FIG. 12  is a cross section of an embodiment of a positive displacement flowmeter showing solid, double bladed displacement rotors and an alternative housing. 
           [0065]      FIG. 13  is a cross section of an embodiment of a positive displacement flowmeter showing solid, triple bladed displacement rotors and an alternative housing. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0066]    As required, detailed embodiments of the present inventions are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
         [0067]    First referring to  FIGS. 1A and 2 , a flowmeter  10  according to one embodiment as shown. The flowmeter  10  comprising a housing or casing  20 , an inlet  50 , a fluid chamber  60 , and an outlet  70 . The housing  20  is comprised of an end wall  22 , a plurality of hole  24 , bolt(s)  26 , a side wall  28 , a bottom wall  30 , a side wall  32 , a top wall  34 , a side interior surface  36 , a bottom interior surface  38 , a side interior surface  40 , and a top interior surface  42 . 
         [0068]    The inlet  50  is comprised of an inlet opening  52 , an inlet channel  54 , an interior surface  55 , and an inlet port  56 . 
         [0069]    The fluid chamber  60  is comprised of an inlet displacement chamber  62 , a central chamber  64 , and an outlet displacement chamber  66 . 
         [0070]    The outlet  70  is comprised of an outlet port  72 , an outlet channel  74 , an interior surface  75 , and an outlet opening  76 . 
         [0071]    The flowmeter  10  attaches to an existing line by connecting the attachment  90  from the existing line to the inlet opening surface  51  of the housing  20 . The surface  91  of the attachment  90  connect with the inlet opening surface  51  of the housing  20 . A sealing means  92  may be located between the attachment  90  and the housing  20 . The attachment  90  is secured to the inlet opening surface  51  of the housing  20  by a plurality of bolts  26  extending through voids in the attachment  90  that line up with voids in the inlet opening surface  51  of the housing  20 . The voids in the inlet opening surface  51  of the housing  20  have a plurality of threads that align with the bolts  26 . 
         [0072]    The same procedure is applicable for connecting an attachment  90  to the outlet opening surface  77  of the housing  20 . 
         [0073]    Once the flowmeter  10  is connected to the attachments  90  at both the inlet opening surface  51  and the outlet opening surface  77 , the substance, typically gas or liquid, can flow through the closed system. The substance will flow from the attachment  90  through the inlet opening  52  into the inlet channel  54 . The inlet channel  54  has an interior surface  55  that define the limits of the path of the substance through the inlet  50 . The substance then goes from the inlet channel  54  through the inlet port  56  into the fluid chamber  60 . 
         [0074]    The fluid chamber  60  is divided into three continuous chambers, namely, the inlet displacement chamber  62 , the central chamber  64  and the outlet displacement chamber  66 , which correspond to the inlet and outlet displacement rotors  300  and the blocking rotor  200 . The meter  100  (Refer to  FIG. 3 ) component of the flowmeter  10  is mounted into the fluid chamber  60 , and will be described in detail later. As the substance enters the inlet displacement chamber  62  of the fluid chamber  60  from the inlet channel  54 , the substance flows from the inlet displacement chamber  62  rotating the inlet displacement rotor  300  through the central chamber  64  where the blocking rotor  300  rotates and into the outlet displacement chamber  66  containing the outlet displacement rotor  300 . From the outlet displacement chamber  66  the substance enters that outlet channel  74  of the outlet  70  through the outlet port  72 . 
         [0075]    After entering the outlet channel  74  through the outlet port  72 , the substance continues through the outlet channel  74  until it reaches the outlet opening  76 . The outlet channel  74  has an interior surface  75  that defines the limits of the flow path through the outlet  70 . The substance then moves through the outlet opening  76  and into the attachment  90  connected to the outlet opening surface  77  of the outlet  70 . 
         [0076]    While described herein the substance moving in one direction through the flowmeter, the meter movement and flow direction are fully reversible without compromising the integrity of the flowmeter or the accuracy of the volume measurement. 
         [0077]    The attachments  90  from the existing lines are generally cylindrical in shape. For purposes a fluid connection, the inlet opening  52  and the outlet opening  76  are cylindrical in shape, but may take any shape consistent with applications known in the art. However, the inlet port  56  and the outlet port  72  are, in general, elongated with a rectangular or oval shape. Therefore, the inlet channel  54  and the outlet channel  74  have a different cross sectional shape as the substance moves from both the inlet opening  52  to the inlet port  56  and from the outlet port  72  to the outlet opening  76 . 
         [0078]    The top interior surface  42  of the fluid chamber  60  of the housing  20  contains two sealing surfaces  80 . The sealing surfaces  80  are angled to provide for contact with the exterior surface  231  of the blocking rotor  200 , described later. 
         [0079]    Located in the bottom wall  30  of the housing  20  of the flowmeter  10  is a void  82  extending from the exterior surface  44  of the housing  20  to the bottom interior surface  38  of the housing  20 . The void  82  has a plurality of threads. A drain plug  84  is inserted into the void  82  from the exterior of the housing  20 . The drain plug  84  is then screwed in conjunction with the plurality of threads to provide a seal that can be removed such that the interior of the flowmeter  10  can be drained by removing the drain plug  84 . 
         [0080]    Having described the preferred embodiment of the housing  20 , the preferred embodiment of the meter  100  is described with reference to  FIG. 3 . The meter  100  comprising a rear cap cover  102 , a rear plate  110 , a blocking rotor  200 , two displacement rotors  300 , a gear housing  120 , displacement gear rotors  140 , displacement gear rotor washers  142 , a blocking gear rotor  150 , a blocking gear rotor driver  152 , compression or spring washer  160 , bolts  162 , a front cover cap  170  and bolts  180 . 
         [0081]    Referring to FIG.  4 ., a blocking rotor  200  as shown comprising a front end wall  210 , a rear end wall  220 , and an arcuate side wall  230 . The front end wall  210  has an end wall void  212  and the rear end wall  220  has an end wall void  222 . The sidewall  230  has an angled sidewall edge  232 . There is a front journal  240  and a rear journal (not shown) that are well known in the art in meter applications such as a flowmeter. The interior of the blocking rotor  200  in the preferred embodiment as shown is a hollow cavity  250 . While the blocking rotor  200  can be solid in certain applications, such as in pumps, as shown in  FIGS. 12 and 13 ,  600 , the preferred embodiment is a hollow cylinder  250 . 
         [0082]    Referring to  FIG. 5 , a displacement rotor  300  as shown comprising a front end wall  310 , a rear end wall  320 , an arcuate side wall  340  and a displacement blade  330 . The arcuate side wall  340  has an angled sidewall edge  342  and an exterior surface  341 . The displacement blade  330  has a displacement surface  332 , a back surface (not shown), and a sealing surface  334 . There is a front journal  360  and a rear journal (not shown) that are well known in the art in meter applications such as a flowmeter. The interior of the displacement rotor  300  in the preferred embodiment as shown is a hollow cylinder  350 . While the displacement rotor  300  can be solid in certain applications, such as in pumps, as shown in  FIGS. 12 and 13 ,  500 , the preferred embodiment is a hollow cavity  350 . 
         [0083]    In the preferred embodiment, the cylindrical size, that is, the radius, diameter and circumference of the cylinder, is the same in both the blocking rotor  200  and the displacement rotors  300 . Modifications to the size of the cylinders may be necessary based upon specific applications, however, the novel similarity between the size of the cylinders are important in creating the uniform flowpath unseen in the prior art. 
         [0084]    The meter  100  is assembled as shown in  FIG. 3 . The blocking rotor  200  and the displacement rotors  300  are inserted into the fluid chamber  60  of the housing  20  of the flowmeter  10 . The displacement rotors  300  occupy the space within the fluid chamber  60  designated at the inlet displacement chamber  62  and the outlet displacement chamber  66 . The displacement rotor  300  within the inlet displacement chamber  62  may be referred to as the inlet displacement rotor. The displacement rotor  300  within the outlet displacement chamber  66  may be referred to as the outlet displacement rotor. The blocking rotor  200  occupies the space within the fluid chamber  60  designated as the central chamber  64 . 
         [0085]    The rear plate  110  contains voids  112  that align with the rear journals (not shown) for both the blocking rotor and the two displacement rotors. The rear journals are inserted through the voids  112  of the rear plate  110 . The rear plate  110  has a plurality of holes  114  that align with the plurality of holes  24  in the end wall  22  of the housing  20  of the flowmeter  10 . 
         [0086]    The rear cover cap  102  has a lip  104  that contains a plurality of holes  106 . The holes  106  align with the holes in the rear plate  110  and the holes in the end wall  22  of the housing  20 . The rear plate  110  and the rear cover cap  102  are attached to the housing  20  by bolts (not shown) that are inserted through the plurality of holes  106  of the rear cover cap  102 , through the plurality of holes  114  of the rear plate  110 , then through the plurality of holes  24  in the end wall  22  of the housing, where the end of the bolt is then secured with a nut or some other securing device known in the art. 
         [0087]    With the rear journals (not shown) resting within the voids  112  of the rear plate  110 , the front journal  240  of the blocking rotor  200  and the front journals  360  of the displacement rotors  300  rest within the voids  126  of the plate  122  of the gear housing  120 . The interior wall  128  of the voids  126  in the plate  122  of the gear housing  120  may contain ball bearings or any other means known in the art for creating a near frictionless centrifical movement. 
         [0088]    The gear housing  120  has a lip  130  extending from the plate  122  that creates a gear chamber  132 . When the front journals  240 ,  360  are inserted through the voids  126  in the plate  126 , a blocking gear rotor  150  is attached to the front journal  240  of the blocking rotor  200  and the displacement gear rotors  140  are attached to the front journals  360  of the displacement rotors  300 . A driver  152  is placed adjacent to the blocking gear rotor  150  with the driver  152  and the blocking gear rotor  150  attached to the front journal  240  of the blocking rotor  200  by a bolt  162  and a compression or spring washer  160 . The displacement gear rotors  140  are attached to the front journals  360  of the displacement rotors  300  by a washer  142 , a compression or spring washer  160 , and a bolt  162 . 
         [0089]    A front cover cap  170  has a lip  172  containing a plurality of holes  174 . The plurality of holes  174  in the lip  172  of the front cover cap  170  align with the plurality of holes  124  in the plate  122  of the gear housing  120  and with the plurality of holes  24  in the end wall  22  of the housing  20 . Bolts  180  are inserted through the plurality of holes  174  in the front cover cap  170 , through the plurality of holes  124  in the gear housing  120  and through the plurality of holes  24  in the housing  20 . The bolts  180  are then secured by nuts or other means of securing a bolt as known in the art, such as threading the holes  174 ,  124 . 
         [0090]    The front cover cap  170  has a drive shaft void  176  for purposes of inserting a drive shaft as known in the art. 
         [0091]    Referring to  FIGS. 1A ,  1 B,  1 C and  1 D, the flow path of the preferred embodiment is demonstrated visually as shown. In a working condition, a given substance, typically either a liquid or gas, will fill the housing  20 , including the inlet and outlet channels  54 ,  74 , the fluid chamber  60 , the cavities  350  of the displacement rotors  300  and the cavity  250  of the blocking rotor  200 . 
         [0092]      FIG. 1A  shows the displacement blades  330  in a vertical, 12 oclock position with the sealing surface  334  of the displacement blades  330  in contact with the top interior surface  42  of the housing  20 . As further shown in  FIGS. 1B ,  1 C and  1 D, the displacement rotors  300  rotate in a direction opposite of the blocking rotor  200 , as shown the displacement rotors  300  move in the counterclockwise direction. 
         [0093]    As the substance moves through the fluid chamber  60 , the substance is prevented from backflowing by seals created by the parts. The sealing surface  80  located on the top interior surface  42  of the housing  20  comes in contact with the exterior surface  231  of the blocking rotor  200  during the rotation of the blocking rotor  200 , such that the substance is forced through the outlet port  72  and cannot reenter the inlet displacement chamber  62 . The exterior surface  341  of the displacement rotors  300  and the exterior surface  231  of the blocking rotor  200  also create a seal by virtue of their close proximity to the other. These seals force the substance moving through the flowmeter to move in a fluid uniform fashion. 
         [0094]    The flow path of this flowmeter  10  is demonstrated in  FIGS. 1A ,  1 B,  1 C and  1 D. While the substance is generally moving through the flowmeter  10  continuously, this description focuses on a set point in the flow of the substance for purposes of demonstration. The substance enters the flowmeter  10  through an outside line, as previously described. The substance enters through the inlet opening  52 , travels through the inlet channel  54 , through the inlet port  56  and enters the inlet displacement chamber  62 . The displacement rotors  300  and the blocking rotor  200 , through their rotation, create the flowpath by which the substance moves through the flowmeter  10 . As the substance pushes the displacement rotor blade  330  through the counterclockwise motion, the blocking rotor  200  and the other displacement rotor  300 , likewise rotate. The pressure for moving the substance remains with the displacement rotor  300  in the inlet displacement chamber  62  until  FIGS. 1C and 1D , when the displacement rotor  300  in the outlet displacement chamber  66  creates the seal and the pressure from the substance forces the outlet displacement chamber  66  displacement rotor  300  to rotate until back in the position of  FIG. 1A . The substance, given the rotation of the displacement rotors  300  and the blocking rotor  200 , moves through the inlet displacement chamber  62 , through the central chamber  64  and through the outlet displacement chamber  66 . The substance then moves through the outlet port  72 , through the outlet channel  74  and exists the flowmeter  10  through the outlet opening  76 . 
         [0095]    The structural similarity of the blocking rotor  200  and the displacement rotors 300 cylinders, in conjunction with the 180 degree axes alignment of the blocking rotor  200  and the displacement rotors  300  in the preferred embodiment, create the unique uniform flowpath by virtue of a similar distance between the exterior surface  231  of the blocking rotor  200  and the bottom interior surface  38  of the housing  20  and the exterior surface  341  of the displacement rotors  300  and the side interior surfaces  36 ,  40  of the housing  20 . This flowpath decreases pressure drop, fluctuation and vibration by virtue of the uniform parts. 
         [0096]    While the preferred embodiment of the flowmeter has a 180 degree line between the axis of the blocking rotor  200  and the axes of the displacement rotors  300 , alternative embodiments permit the use of the single cavity blocking rotor  20  utilizing a larger hub and shorter blade protrusion of the preferred displacement rotors  300 . (Refer to  FIGS. 12 and 13 ). 
         [0097]    Referring to  FIGS. 6 ,  7  and  8 , the angular relation between the rotational axes of the displacement rotors and the axis of the blocking rotor  400  is shown. The change in the angular relation  400  is possible by changing the position of the sealing surface  80  in relation to increases and decreases in the size of the endwall voids  212 ,  222  that correlate to changes to the exterior surface  231  parameters. Changes to the housing  20  would correspond as shown to the particular angular relationship  400  implemented in the flowmeter  10 . The unique structure of the displacement rotors  300 , in conjunction with the single recess blocking rotor  200 , allows deviation from the 180 degree preferred embodiment axial alignment without the interference and/or obstruction of the flowpath by the parts. 
         [0098]    Referring to  FIG. 9 , another embodiment of this flowmeter  10  provides for the attachment  90  connecting directly to the fluid chamber  60  via an inlet port  56  without the inlet and outlet channels  74 ,  54  as seen in the preferred embodiment above. This alternative embodiment allows the application of the preferred embodiments displacement rotors  300  and the single cavity blocking rotor  200 , as well as the preferred configuration of the apparatus to create the flow path as shown in  FIGS. 1A ,  1 B,  1 C, and  1 D, into the alternative embodiment that is useful for certain applications where the preferred embodiment cannot be attached to the industrial application. Changes to the housing  20  structure may be required depending on the desired attachment site of the existing line. 
         [0099]    Referring to  FIGS. 10 and 11 ,  FIG. 11  shows the preferred embodiment cross-over inlet  50  and outlet  70 . An alternative embodiment, as shown in  FIG. 10 , shows an inlet  50  with a bifurcated inlet chamber  54   a ,  54   b . The alternative embodiment allows for two flow channels into the inlet displacement chamber  62  while the preferred embodiment has one solitary flow channel. 
         [0100]    Referring to  FIGS. 12 and 13 , alternative embodiments are shown with solid blocking rotors  600  and solid displacement rotors  500 .  FIG. 12  shows an alternative embodiment with displacement rotors  500  with two blades  510 .  FIG. 13  shows an alternative embodiment with displacement rotors  500  with three blades  510 . The alternative embodiments in  FIGS. 12 and 13  allow for the single cavity blocking rotor  600  as described in the preferred embodiment  200 . Changes to the blocking rotor  600  in  FIGS. 12 and 13  include removal of the angled sidewall edge  232  as seen in the preferred embodiment. Other alternatives as shown include modifications as needed to the housing  20  of the flowmeter  10 . 
         [0101]    In the foregoing description, certain terms have been used for brevity, clearness and understanding; but no unnecessary limitations are to be implied therefrom beyond the requirements of the prior art, because such terms are used for descriptive purposes and are intended to be broadly construed. Moreover, the description and illustration of the invention is by way of example, and the scope of the invention is not limited to the exact details shown or described. 
         [0102]    Certain changes may be made in embodying the above invention, and in the construction thereof, without departing from the spirit and scope of the invention. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not meant in a limiting sense. 
         [0103]    Having now described the features, discoveries and principles of the invention, the manner in which the inventive flowmeter for measuring the flow of substances is constructed and used, the characteristics of the construction, and advantageous, new and useful results obtained; the new and useful structures, devices, elements, arrangements, parts and combinations, are set forth in the appended claims. 
         [0104]    It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.