Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C2/00—Rotary-piston machines or pumps
  • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
  • F04C2/10—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member
  • F04C2/107—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member with helical teeth
  • F04C2/1071—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member with helical teeth the inner and outer member having a different number of threads and one of the two being made of elastic materials, e.g. Moineau type
  • F04C2/1073—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member with helical teeth the inner and outer member having a different number of threads and one of the two being made of elastic materials, e.g. Moineau type where one member is stationary while the other member rotates and orbits

Definitions

• the invention relates to a conical Moineau Pump according to the introductory portion of claim 1.
• a Moineau Pump is often referred to as a progressing cavity pump (PCP) and can be used for various purposes.
• PCP progressing cavity pump
• These pumps comprise an outer and an inner element, whereas the inner element is arranged in a central cavity of the ring shaped outer element.
• the outside of the inner element and the inner side of the outer element both have a helical or screw-shaped contour forming a helical groove on the inside of the outer element and a helical groove on the outside of the inner element.
• the inner element is rotating along its longitudinal axis and along a circular path around the longitudinal axis of the outer element. Thereby, the outer surface of the inner element is in contact with the inner surface of the outer element.
• a special form of such Moineau Pump is a conical Moineau Pump.
• Conical Moineau Pumps have a cavity in the outer element which widens from one end to the other, i.e. has a smaller diameter on its first end than on its opposed second end.
• the inner element has a corresponding conical shape, i.e. expanding from one to the other end.
• conical Moineau Pumps the longitudinal axes of the inner and outer element are inclined to one another, i.e. intersecting in one intersection point.
• the Moineau Pump comprises a basically ring-shaped outer element having a conical cavity along its longitudinal axis.
• This ring-shaped outer element on its inner side has a helical path or contour as known from conventional Moineau Pumps.
• the Moineau Pump comprises a conical inner element arranged in said cavity of the ring-shaped element.
• This inner element has a helical contour or path on its circumferential outer surface as known from conventional Moineau Pumps.
• the helical contour of the outer element has one more thread than the helical contour on the inner element.
• the Moine ⁇ u Pump according to the invention is a conical Moineau Pump
• the cross section or diameter of the cavity of the outer element increases from one end to the opposite other end.
• the inner element has a corresponding conical shape, i.e. a cross section or diameter increasing from one end to the opposite other end.
• the longitudinal axis of the inner element is inclined to the longitudinal axis of the outer element, both axes are intersecting in one intersection point. This intersection point is preferably the point at which the inner element or outer element is connected with a drive shaft.
• the cavity of the outer element has an optimized shape.
• the cavity is shaped so that it is a spherical cross section which has the intersection point of said longitudinal axes as a centre forms a hypocycloid or an epicycloid.
• any spherical cross section of the cavity having said intersection point of that longitudinal axes, i.e. the longitudinal axis of the inner element and the longitudinal axis of the outer element, as a centre forms a hypocycloid or an epicycloid.
• the spherical cross-section of the cavity may have the form of a hypocycloid or an epicycloid itself or of an offset of such hypocycloid or epicycloid.
• Such offset contour is generated if a ball or circle with the radius R (offset) is moved along a hypocycloid or an epicycloids path, whereas the centre point of the ball or circle follows this path.
• the offset contour defines the line or surface on which the circle or ball would have to roll so that its centre is moved along the hypocycloid or epicycloid path.
• An outer element having an inner contour designed so that a, preferably any spherical cross section forms a hypocycloid or an epicycloid enables a better or more precise fit of the inner element inside the cavity of the outer element.
• Such a better fit of inner and outer element guarantees that the pressure zones between inner and outer element are leak-tight even at higher pressures. Therefore, with the Moineau Pump according to the invention higher pressures may be generated. Further, the better fitting results in a high efficiency, since friction between outer and inner element is reduced. Further, the wear of the pump is reduced so that the service life of the pump may be lengthened. Moreover, the reduced friction has the advantage of a lower starting torque required for starting the pump.
• the need for providing the inner and/or outer element with a resilient surface material is at least partly eliminated. Further, the design according to the invention makes the pump being less sensitive to dry running.
• the spherical cross section forms a hypotrochoid or an epitrochoid.
• the spherical cross section may have the form of a hypocycloid or a hypotrochoid or of an epicycloid or an epitrochoid.
• the hypocycloid or epicycloid design of the cavity of the outer element may have a different number of lobes.
• the hypocycloid or epicycloid may be a three-lobe hypocycloid or epicycloid or for example a four- lobe hypocycloid or epicycloid, respectively.
• the exact design of the spherical cross section of the cavity mainly depends on the form of the rotor.
• the spherical cross section has a form of a hypocycloid with one or more lobe.
• the spherical cross- section of the cavity in the outer element has the form of a two-lobe hypocycloid, further preferred with an offset corresponding to the radius of the inner element.
• geometries of the spherical cross- section of the outer element in form of ⁇ hypocycloid or epicycloid having a higher number of lobes may be beneficial due to the quantitative smaller but more frequent thrust or torque peaks, in particular thrusts in axial direction.
• the spherical cross section of the inner element having said intersection point of said longitudinal axes as a centre has a round form or the form of a hypocycloid or an epicycloid.
• the spherical cross section of the inner element corresponds to the spherical cross section of the cavity so that the inner element can make an eccentric movement inside the cavity, i.e. rotate around the longitudinal axis of the inner element, whereas the longitudinal axis of the inner element at the same time rotates around the longitudinal axis of the cavity. This means the inner element is rolling on the inner surface of the cavity.
• At least the inner surface of the cavity or outer element and at least the outer surface of the inner element are made out of the same material.
• At least the inner surface of the outer element and/or at least the outer surface of the inner element are made out of a non-resilient material.
• both surfaces which come into contact with one another during operation of the pump are made of a hard material, i.e. a non-resilient material.
• hard material is meant a material with low resilience such as for example metal and certain types of composite materials. It would be beneficial to apply wear-resistant materials in order to achieve a long service life of the pump.
• at least the inner surface of the outer element and/or at least the outer surface of the inner element may be made out of a plastic material, a ceramic material, metal or composite material.
• This may for example be instance polyamide, polyamide-imide (PAI), poly- etheretherketones (PEEK) or filled epoxy or phenolic resin.
• PAI polyamide-imide
• PEEK poly- etheretherketones
• filled epoxy or phenolic resin such materials secure a long service life due to the materials wear-resisting properties.
• the application of these materials makes it possible to use the pump in an aggressive environment (pumping acids, hot water or dry conditions with no fluid), which would not be possible with conventional pumps comprising a rubber coated stator.
• both, the inner element and the outer element or at least their surfaces coming into contact with one another are made of the same material, for example a plastic material or ceramics.
• it is also possible to combine several types of material so that for example the inner element is made out of one material and the outer element is made of another material.
• Composite materials may be beneficial due to their flexibility with regard to shape and design.
• the inner and/or outer element may at least partially comprise more than one material layer.
• the surface of the element, in particular the outer surface of the inner element and the inner surface of the cavity of the outer element are made of special wear-resistant material, in particular a non-resilient material.
• a Moineau Pump that is designed to have an optimal geometry when the pump has been subject to a certain wear.
• the outer layer of the inner or outer element which comes into contact with the surface of the other element for example the outer surface of the inner element may be produced from a material which should show a certain wear when the pump is operated for the first time or the first times, thereby a certain amount of material is removed due to fric- tion between the inner and the outer element so that the cavity of the outer element and/or the outer surface of the inner element becomes the optimal shape, depending which surface is made from the respective material.
• This allows to produce the pump with reduced tolerance requirements, rotor and stator, i.e. inner and outer element, are automatically brought into the optimal shape during operation of the pump because of desired or allowed wear on the surface of the inner and/or outer element (cavity of the outer element).
• the internal element within the external element in a manner that permits that the internal element may be moved towards the external element and still fits in the channel or cavity inside the external element. This allows maintaining the optimal fit even after a certain amount of wear occurred. Because of the conical shape and the cross section according to the invention it is possible to just move or press the inner element more into the cavity of the outer element.
• the internal element and/or the external element are provided with at least one layer of a friction decreasing material.
• a friction decreasing layer comprising polytetrafluoroethylene (Teflon), graphite or another lubri- cative.
• the outer and the inner element are movable relative to one another along the longitudinal axis of the outer element.
• the pump may be designed in a manner that the fluid pressure generated by the pump acts on the inner and/or outer element to press both elements together so that the contact force between both elements increases with increasing pump pressure of the pumped substance or fluid.
• the internal and external elements are pressed together by the pressure generated in the pump only a very small force is needed to press the elements together during the start of the pump. Therefore, only a small starting torque is required.
• a plane cross section of the flow path between inner and outer element normal to the longitudinal axis, in particular the longitudinal axis of the outer element has the same magnitude for all plane cross sections along said longitudinal axis or decreases along the longitudinal axis of the outer element.
• the flow path through the pump has a constant cross-sectional area which secures a constant flow and will avoid cavitation.
• the plane flow path cross-section decreases along the longitudinal axis of the outer element.
• the plane flow path cross-section decreases only slightly along the longitudinal axis of the outer element. The decrease should advantageously extend in the direction of the flow.
• the maximum distance between the longitudinal axis of the inner element and the longitudinal axis of the outer element is in the range of 0 to 50% of the length of the inner element along its longitudinal axis and preferably in the range of 1 to 10% of the length of the inner element along its longitudinal axis.
• the eccentricity of the motion between inner and outer element is in a range of 0 to 50% of the length of the inner element along its longitudinal axis.
• the eccentricity varies linearly along the axis of the inner element.
• the eccentricity is zero at the intersection point of both longitudinal axes and has a maximum at the opposite end of the internal element.
• the maximum of the eccentricity lies within the range of 0 to 20% of the length of the internal element, further preferred within the range of 1 to 10% of the length of the internal element.
• inner and outer element will fulfil a relative movement to one another during operation of the pump.
• the inner element may act as a rotor whereas the outer element acts as a stator.
• the outer element acts as a rotor and the inner element acts as a stator.
• both elements may be in motion, i.e. rotate relatively to one another so that the inner element fulfils an eccentric motion inside the outer element.
• Fig. 1 a schematic diagram of a spherical cross-section in a perspective view.
• Fig. 2 a cross-section according Fig. 1 in a top view
• Figs. 3a-3c three examples of hypocycloids
• Figs. 4a-4c the spherical cross-sectioned profiles of outer elements of Moineau Pumps according to the invention generated from hypocycloid geometries.
• Figs. 5a-5c spherical cross-sectioned lobe profiles of inner elements at different positions on their paths within the cavity of an outer element corresponding to the spherical cross- section of the outer element as shown in Fig. 4a,
• Figs. 6a-c spherical cross-sectioned view of lobe profiles of inner elements at different positions on their paths within a cavity of outer element corresponding to the cavity of the outer element generated by a three-lobe geometry as shown in Fig. 4b and
• Fig. 7 a schematic cross-section of a pump according to the invention.
• the Moineau Pump according to the invention has two main parts, an outer element 2 and inner element 4, wherein the outer element 2 may be a stator of the pump and the inner element 4 may be a rotor of the pump.
• the inner element 4 has a longitudinal axis Y and the outer element 2 has a longitudinal axis X. Since the Moineau Pump according to the invention is a conical Moineau Pump both axes are inclined relatively to each other and intersect in one intersection point I as can best seen in the schematic diagram of Fig. 1.
• the inner element 4 is arranged in ⁇ cavity 6 of the outer element 2.
• Both, the cavity 6 and the inner element 4 have a conical shape, this means their cross-sectional area or diameter normal to their longitudinal axes increases from one end to the other.
• Fig. 7 on the left side which is the pressure side of the pump inner element 4 and cavity 6 have the smallest cross-sectional area and on the right side which is the suction side of the pump they have their biggest cross-sectional area.
• the inner element 4 fulfils an eccentric movement inside the cavity 6 and rolls on the inside of the outer element 2, i.e. on the inner circumferential surface of the outer element 2 defining cavity 6.
• inner element 4 and outer element fulfil a relative movement to each other.
• the outer element 2 is the stator and the inner element 4 is a rotor
• the inner element 4 rotates along its longitudinal axis Y, whereas at the same time the inner element 4 and its longitudinal axis Y rotate around the longitudinal axis X of the outer element 2.
• the inner element 4 fulfils an eccentric movement inside the cavity 6, wherein the eccentricity increases starting from the intersection point I, where the eccentricity is 0, to the opposite end of the cavity 6.
• the important characterizing feature of the invention is the special design of the outer element 4 and its cavity 6 along a spherical cross- section C which is shown in Fig. 1.
• the spherical cross-section C is a cross-section along a surface of a sphere, wherein the intersection point I of the longitudinal axis X, Y forms the centre of the sphere.
• the spherical cross-section of the cavity 6 has a geometry of a two-lobe hypocycloid.
• the inner element 4 has a circular cross section but the cross-section of the cavity 6 in the outer element 2 is not symmetric in a plane cross- section, however, the spherical cross-section as shown in fig. 1 is symmetric.
• any spherical cross-section of the cavity 6 having said intersection point I as a centre forms a hypocycloid or an epicycloid.
• This means for any radius of the sphere along which the cross section is take the geometry of the cavity is a hypocycloid or epicycloid or an offset thereof.
• Figs. 3a-3c show three examples of hypocycloids.
• a hypocycloid is formed by a point P on the circumference of a small circle 8 rolling along the inside of larger outer circle 10.
• Fig 3a shows a two-lobe hypocycloid which is formed when the small circle has half the diameter of the outer larger circle 10.
• Fig. 3b shows a three-lobe hypocycloid which is formed when the larger circle has three times the diameter of the small circle 8.
• Fig. 3c shows a four-lobe hypocycloid which is formed when the larger circle 10 has four times the diameter of the small circle 8.
• point P for a two-lobe hypocycloid moves along a straight line.
• the three-lobe hypocycloid has the form of a triangle with concave sides on which point P moves when rolling circle 8 along the inner circumference of larger circle 10.
• the path of point P has the form of a square with concave sides.
• Figs. 4a-4c show profiles or spherical cross-sections of a cavity 6 formed on basis of the hypocycloids shown figs. 3a, 3b and 3c, i.e. the cavity according to fig. 4a is based on a two-lobe cycloid, the cavity 6 of fig. 4b on three-lobe cycloid and the cavity 6 according fig. 4c on a four- lobe cycloid.
• the cavities 6 are defined by an offset R added to the hypocycloid geometries as shown in fig. 3a to fig.3c.
• the offset R is a radius R of circle or ball moving along a line defined by the hypocycloid according to fig.
• Figs. 5a to 5c show ⁇ spherical cross-sectioned view of a rotor 2 inside cavity 6 according to fig. 4a in three different positions. This two-lobe geometry of the hypocycloid cross-section is a preferred embodiment.
• the rotor 2 When moving the inner element 2 (rotor in this example) inside the cavity 6 by rotating the axis Y around axis X and rotating the inner element 2 around its longitudinal axis Y the rotor 2 according to the embodiment shown in fig 4a and 5a to 5c moves along a straight line 12 in the curved plane of the spherical cross section, i.e. oscillates on a circle line along the spherical cross-section with the intersection point I as a centre of this circle line.
• Fig. 6a to 6c show the profile or geometry of cavity 6 and the inner element 2 along the spherical cross-section for a three-lobe hypocycloid according to fig. 3b and 4b.
• Fig. 6a, 6b and 6c show three different positions of the inner element 2 during the movement of the inner element 2 inside the outer element 4 when operating of the pump.
• the rotor 2 has an oblong shape with opposed ends in form of half circles. The two centre points 14 of these half circles are moving on a hypocycloid path as shown in fig. 3b, wherein the half circles have a radius R as shown in fig. 4b so that the surface of the inner element 2 comes into contact with the inner surface 15 of the outer element 4, i.e. the wall defining cavity 6.
• the inner element 2 can roll on said wall defining cavity 6.
• the important advantage of the design of cavity 6 and the corresponding design of the inner element 2 along any spherical cross-section so that the outer form of the cavity follows a hypocycloid curve or a hypocycloid curve with an offset (radius R) is that the inner element 2 can fulfil a more precise movement inside the outer element 4. This allows reducing the tolerance requirements and it is not required to use resilient materials for the surface of the inner element 2 and/or the inner surface 15 of the outer element 4. With the design according to the invention both surfaces may be made from a non-resilient material. This results in a greater stiffness of the surface and keeps the pressure zones between inner element 4 and outer element 2 leak-tight even at high pressures.
• Fig. 7 shows a special embodiment of the invention in which the outer element 2 is movable relative to the inner element 4 along the longitudinal axis X.
• This allows that the pressure generated by the pump acts on the outer element 2 and forces the outer element 2 against or inside the inner element 4. By this force the pressure zones may be kept leak- tight even at higher pressures inside the pressure zones.
• the pressure force between outer element 2 and inner element 4 is reduced at lower fluid pressures, in particular when starting the pump, so that wear and torque can be reduced in such operating conditions.
• the pressure on the pressure side 20 of the pump acts on the outer element 2 in the axial direction along longitudinal axis X.
• the outer element 2 is mounted on bearing elements 22 which are slidable in longitudinal direction Y inside a housing 24.
• the inner element 4 or rotor 4, respectively, is supported in longitudinal directions via bearing elements which are not shown in fig. 7.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Rotary Pumps (AREA)
• Diaphragms For Electromechanical Transducers (AREA)
• Amplifiers (AREA)
• Inorganic Insulating Materials (AREA)

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Citations (4)

• 2007
  • 2007-05-04 DE DE602007013183T patent/DE602007013183D1/de active Active
  • 2007-05-04 EP EP07009009A patent/EP1988288B1/de active Active
  • 2007-05-04 AT AT07009009T patent/ATE502214T1/de not_active IP Right Cessation
• 2008
  • 2008-03-18 WO PCT/EP2008/002133 patent/WO2008135116A1/en active Application Filing

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