Abstract:
This disclosure describes new construction for rotary elements that find use in rotary displacement devices, e.g., positive displacement pumps and meters. The proposed construction may incorporate fibers, e.g., carbon fibers, disposed in a resin matrix. This construction can reduce the need to perform secondary processes that are necessary to utilize many rotary elements of conventional design. Moreover, examples of the rotary elements can improve operation of the displacement devices, e.g., by reducing resonance and allowing the displacement device to operate at increased speed.

Description:
BACKGROUND 
       [0001]    The subject matter disclosed herein relates to rotary displacement devices including pumps and meters that utilize multi-lobed rotating elements. 
         [0002]    Rotary-style displacement devices are compatible with a wide range of fluids (e.g., liquids and gases). These devices may include a housing that forms a chamber with an inlet and an outlet. Inside of the chamber, the devices often have a pair of elements that can rotate in opposite directions during operation. The elements mesh with one another to transport, or displace, a known quantity of fluid from the inlet to the outlet. When the device operates as a pump, the elements are actively rotated to facilitate movement of the fluid from the inlet to the outlet of the chamber. On the other hand, when the device operates as a meter, fluid flow acts on the elements. The force of the fluid causes the elements to rotate, which in turn can generate an output (e.g., am electrical signal) that reflects one or more characteristics of the fluid flow. 
         [0003]    Performance of these rotary-style displacement devices relies heavily on the construction of the rotating elements. Dimensions for the parts are, for example, held to very tight tolerances to ensure proper fit, mesh, and engagement during rotation. As a competing interest, however, cost considerations lend manufacture of the rotating elements to materials (e.g., iron) and techniques (e.g., casting) that do not necessarily meet the standards for efficient operation of the displacement device. The result is often the need for extensive secondary processing (e.g., machining) of the rotating elements to establish proper fit up, clearances, balance, and mating at the assembly stages. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    This disclosure describes new construction for rotary elements that find use as rotors and impellers in rotary displacement devices, e.g., positive displacement pumps and meters. Broadly, exemplary construction of the rotary elements utilizes carbon fibers and a resin to form a stiff, light-weight structure. This structure can withstand operating conditions (e.g., pressure, temperature, etc.) of various working fluids (e.g., gas and liquids). Examples of the structure arrange the carbon fibers in a single direction, e.g., along the axis of rotation of the rotary elements. This arrangement of the carbon fibers lends itself to pultrusion processes, which can scale production of the rotary elements to reduce manufacturing costs as compared to conventional impeller designs. The structure also requires little secondary machining during fit-up and assembly, thereby reducing labor and assembly costs. Moreover, the favorable features of the rotary elements set forth below can improve operation of the rotary displacement devices, e.g., by reducing resonance and allowing the rotary displacement device to operate at increased speed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    Reference is now made briefly to the accompanying Appendix, in which: 
           [0006]      FIG. 1  depicts a perspective, exploded view that shows an embodiment of a rotary assembly that includes an example of rotary elements in position on a rotary displacement device; 
           [0007]      FIG. 2  depicts a detail, cross-section view of  FIG. 1  to illustrate one exemplary construction of the rotary elements; 
           [0008]      FIG. 3  depicts a perspective view of a rotary assembly that includes rotary elements that have a first configuration; 
           [0009]      FIG. 4  depicts a perspective view of a rotary assembly that includes rotary elements that have a second configuration; and 
           [0010]      FIG. 5  depicts a schematic diagram of a system that can execute a pultrusion process to manufacture rotating elements, e.g., the rotating elements of  FIGS. 1 ,  2 ,  3 ,  4 . 
       
    
    
       [0011]    Where applicable like reference characters designate identical or corresponding components and units throughout the several views, which are not to scale unless otherwise indicated. 
       DETAILED DESCRIPTION 
       [0012]      FIG. 1  depicts a schematic diagram of an exemplary embodiment of a rotating assembly  100 . The rotating assembly  100  includes one or more rotating elements (e.g., a first rotating element  102  and a second rotating element  104 ). Examples of the rotating elements  102 ,  104  have a body  106  with a rotary axis  108 . During operation, the body  106  rotates about the rotary axis  108 , as generally identified by an arrow marked with the numeral  110 . The body  106  can have one or more radial sections (e.g., a first radial section  112  and a second radial section  114 ), which extend radially away from the rotary axis  108 . As described more below, the radial sections  112 ,  114  can have an outer profile with features that form, in one example, generally curvilinear ends and grooves and/or flutes in the body  106  that extend longitudinally along the rotary axis  108 . 
         [0013]    The rotating assembly  100  is part of a rotary displacement device  116  that includes devices (e.g., pumps and meters) that accommodate a working fluid (e.g., gas and liquid). The rotary displacement device  116  includes a housing  118  and a cover  120 . The housing  118  has a peripheral wall  122  that forms an inner volume  124 . When the displacement device  116  is assembled, the housing  118  and the cover  120  couple together to enclose the rotating elements  102 ,  104  in the inner volume  124 . This configuration can seal the inner volume  124  to prevent leaks of the working fluid therefrom. As shown in  FIG. 1 , one or more openings (e.g., a first opening  126  and a second opening  128 ) penetrate through the peripheral wall  122 . The openings  126 ,  128  allow ingress and egress into the inner volume  124  from outside of the housing  118 . In one example, the openings  126 ,  128  include an inlet and an outlet (or discharge) that allow fluids (e.g., gas and liquids) to flow into the inner volume  124  (e.g., via the inlet) and to flow out of the inner volume  124  (e.g., via the outlet). 
         [0014]    Examples of the rotary displacement device  116  facilitate movement of fluid and/or measure movement of fluid that flows in the inner volume  124 , as desired. In one implementation, for example, the rotary displacement device  116  can operate as a pump and/or blower to draw fluid into the inner volume  124 , via the inlet, and expel fluid from the inner volume  124 , via the outlet. In another implementation, the rotary displacement device  116  can operate as a meter and/or measurement device, which monitors flow characteristics (e.g., flow rate) of fluid that flows from the inlet to the outlet. 
         [0015]    The rotating elements  102 ,  104  include rotors and impellers that rotate within the inner volume  124 . Although not shown in the example of  FIG. 1 , the rotary elements  102 ,  104  may secure to a shaft that aligns with the rotary axis  108 . The shaft may secure to the housing  118  and/or the cover  120 , e.g., using bearings that allow the shaft to rotate relative to the cover  120  and the peripheral wall  122 . 
         [0016]    Construction of the body  106  may incorporate materials that improve characteristics of the rotating elements  102 ,  104 . As set forth more below, exemplary materials may include carbon fibers and/or other plastics, polymers, and composites that afford the rotating elements  102 ,  104  with characteristics that are superior to metals (e.g., cast iron and aluminum) found in many conventional designs. For example, carbon fibers can reduce the weight of the rotating elements  102 ,  104  by 15% or more, e.g., with respect to steel. Carbon fibers also increase the strength and stiffness of the rotating elements  102 ,  104 . These improvements can raise the modal frequency of the rotating elements  102 ,  104  to avoid resonance and other problems that often limit operating speeds for pumps and meters (e.g., rotary displacement device  106 ). 
         [0017]      FIG. 2  illustrates a schematic diagram of a cross-section of the body  106  to illustrate one exemplary construction of the rotating elements  102 ,  104  ( FIG. 1 ). As shown in  FIG. 2 , this construction utilizes a composition  130  that comprises a composite material with one or more components (e.g., a matrix component  132  and a fiber component  134 ). The fiber component  134  can comprise a plurality of fibers and/or elongated elements that extend through the matrix component  132 . The matrix component  132  can comprise a resin that binds the fibers of fiber component  134 . 
         [0018]    Broadly, examples of the components  132 ,  134  are found in carbon-fiber reinforced polymers, carbon-fiber reinforced thermoplastics, and similar materials that provide excellent physical (e.g., light weight) and mechanical properties (e.g., high strength and stiffness). In one example, the composition  130  is generally homogenous throughout the body  120 . This homogeneity affords the rotating elements  102 ,  104  with uniform properties throughout the body  106  and/or throughout the constituent components (e.g., the first radial section  114  and the second radial section  116 ). 
         [0019]    Properties of carbon fibers and like composites can also reduce costs of construction and manufacture. Examples of the composition  130  are amenable to manufacturing processes (e.g., extrusion, pultrusion, molding, etc.) that benefit from economies of scale and quantity of production. These manufacturing processes also afford the rotating elements  102 ,  104  with exterior surfaces and profiles that require limited, to no, secondary processes to establish proper fit up during assembly. This feature provides substantial savings on labor costs and assembly time because extensive re-work of the rotating elements  102 ,  104  to meet tight tolerance specification is not necessary as compared to rotors and impellers found of conventional (e.g., metal) construction. 
         [0020]    Examples of the resin of the matrix component  132  include various polymers, e.g., epoxy, polyester, vinyl ester, and/or nylon. Selection of the resin may depend on one or more operating characteristics of the rotary displacement device  116  ( FIG. 1 ). These operating characteristics include fluid temperature and fluid pressure. For example, devices that operate at high temperatures may require resins that can withstand prolonged operation and exposure in those environments. To this end, exemplary resins can exhibit properties that withstand operating temperatures (e.g., fluid temperatures in the rotary displacement device  116 ) of at least about 350° F. or more. 
         [0021]    As mentioned above, fibers in the fiber component  134  can include carbon fibers, although the present disclosure contemplates other fibers that have different material compositions. The material composition can determine the physical and mechanical properties of the rotating elements  102 ,  104 . Use of carbon fibers (and compositions and derivations thereof), for example, can reduce the weight, increase the stiffness, and improve uniformity of the rotating elements  102 ,  104  as compared to elements that use metals. In one example, the fibers can vary in stiffness (also “modulus”), with one example of the fiber component  134  utilizing carbon fibers of standard and/or intermediate modulus. This disclosure contemplates other constructions that may utilize low modulus and high modulus fibers, as well as combinations of fibers having relatively different modulus (e.g., intermediate and high modulus) within the fiber component  134 . 
         [0022]    The properties of the rotating elements  102 ,  104  can also benefit from the fibrous structure of the fiber component  134 . This fibrous structure can utilize various arrangements and patterns of fibers in the body  106 . These patterns can improve strength and stiffness, while also promoting the homogeneity discussed above. In one construction, a majority of the fibers in the composition  130  form a uni-directional pattern. The uni-directional pattern arranges most, if not all, of the fibers in a single direction. This direction can, in one example, place the fibers in axial alignment along the rotary axis  108  ( FIG. 1 ). 
         [0023]      FIGS. 3 and 4  depict exemplary construction of a rotating assembly  200  ( FIG. 3 ) and a rotating assembly  300  ( FIG. 4 ). In  FIG. 3 , the rotating elements  202 ,  204  include one or more lobed impellers (e.g., a first lobed impeller  236  and a second lobed impeller  238 ). The lobed impellers  236 ,  238  have an outer profile  240  that forms one or more lobes (e.g., a first lobe  242  and a second lobe  244 ) offset by an angle  246 . The lobes  242 ,  244  exemplify the curvilinear ends and grooved and/or fluted features for the rotating elements mentioned above and contemplated herein. In the example of  FIG. 3 , the offset angle  246  is about 180°. As best shown in  FIG. 4 , the lobed impellers  336 ,  338  includes a third lobe  348  in addition to the first lobe  342  and the second lobe  344 . Impellers of the type shown in  FIG. 4  are often called tri-lobe impellers, deploying the lobes  342 ,  344 ,  348  at an offset angle  346  of about 120°. 
         [0024]    During operation, the lobed impellers (e.g., the lobed impellers  236 ,  238  and the lobed impellers  336 ,  338 ,  348 ) rotate around the rotary axis (e.g., rotary axis  208  and rotary axis  308 ). The exterior profiles  240 ,  340  mesh together to promote fluid movement (e.g., as a pump) and/or to measure fluid (e.g., as a meter). In one example, in bi-lobed impellers, movement of the lobed impellers  236 ,  238  traps and discharges fluid at least four time during each revolution. For tri-lobed impellers, the movement of the lobed impellers  336 ,  338 ,  348  traps and discharges fluid at least 5 times or more during each revolution. 
         [0025]      FIG. 5  depicts a schematic diagram of an exemplary system  400  that can execute processes to manufacture the rotating elements, as set forth herein. Moving from left to right in the diagram, the system  400  includes a fiber feed component  402  with one or more fiber rolls (e.g., a first fiber roll  404 , a second fiber roll  406 , and a third fiber roll  408 ). The fiber rolls  404 ,  406 ,  408  hold fibers  410  (also “fiber tows  410 ”). The system  400  also includes one or more rollers (e.g., a first roller  412  and a second roller  414 ) to maintain tension in the fibers  410  as the fibers  410  transit the system  400 , as discussed more below. The system  400  also includes a matrix bath component  416  that holds a matrix  418  therein, a die component  420 , and a pull mechanism  422 . In one example, the system  400  also includes a cutting component  424 . 
         [0026]    Examples of the system  400  can execute a pultrusion process. Broadly, pultrusion is a continuous molding process which “pulls” fibers  410  into the matrix  418  and through the die component  420 . As contemplated herein, examples of the fibers  410  can include carbon fiber and/or glass, alone and/or together. The system  400  draws the fibers  410  from the fiber feed component  402  through the matrix  418 . This feature ensures that the matrix  418  thoroughly impregnates, or wets, the fibers  410  in the matrix bath component  416 . The die component  420  may include a die to form the wet-out fiber from the matrix bath component  416 . Examples of the die can include an aperture and/or opening that has the desired geometric shape and exterior profile for the rotating element (e.g., exterior profiles  240 ,  340  that generate the bi-lobe and tri-lobe rotating elements of  FIGS. 3 and 4  above). The die component  420  may incorporate a heater that heats the die. In one implementation, the temperature of the die component  420  initiates curing of the matrix  418 , e.g., by controlling the elevated temperature of the die. Curing solidifies the matrix  418  about the fibers  410  in the shape of the opening in the die as the system  400  continuously pulls the combination of the fibers  410  and matrix  418  through the die. 
         [0027]    In the example of  FIG. 7 , fibers  410  may include standard modulus or intermediate modulus carbon fiber that are pulled through the matrix bath component  416 . This process impregnates the carbon fibers with, in one example, thermoset resin (e.g., polyester resin). Within the die component  420 , the wetted carbon fibers may encounter one or more forming guides, which align the fibers to deliver the designed mechanical properties before the fiber/resin composition enters a die made of steel. The die may form the fiber/resin composition into bi-lobe or tri-lobe shapes. The forming guides may also strip off excess resin from the fiber/resin composition, reducing the hydraulic pressure caused by the materials entering the die. In one implementation, this process can result in a fiber pattern in which the fibers are aligned uni-directionally in the pre-formed shape. This composition is pulled through the heated die, where the fiber/resin composition can develop its final cross sectional bi-lobe or tri-lobe shape. The heat in the die initiates an exothermic reaction within the formulated resin to complete the cure. The finished bi-lobe or tri-lobe profile will be continuously pulled from the die by a pulling device. In one example, the finished profile will be cut to a desire length, e.g., by the cutting component  424 . Pultrusion process requires little operator input besides maintaining material supply and it is cost effective in terms of waste and producing part with consistent quality at higher throughput. Typically pultruded parts have no voids/porosity and have uniform mechanical properties across the length and width. The process provides maximum flexibility in the design of uniform cross-sectional profiles. 
         [0028]    As used herein, an element or function recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural said elements or functions, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the claimed invention should not be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
         [0029]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.