EP3827172A1 - Volumetric pump with flow complementary radial cams - Google Patents
Volumetric pump with flow complementary radial camsInfo
- Publication number
- EP3827172A1 EP3827172A1 EP19742214.0A EP19742214A EP3827172A1 EP 3827172 A1 EP3827172 A1 EP 3827172A1 EP 19742214 A EP19742214 A EP 19742214A EP 3827172 A1 EP3827172 A1 EP 3827172A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- cams
- rotation
- radial
- cam
- axis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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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
- F04C2/30—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members
- F04C2/34—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members
- F04C2/344—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member
-
- 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
- F04C11/00—Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations
- F04C11/001—Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations of similar working principle
-
- 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
- F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
- F04C14/02—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations specially adapted for several machines or pumps connected in series or in parallel
-
- 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
- F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
- F04C15/0042—Systems for the equilibration of forces acting on the machines or pump
- F04C15/0049—Equalization of pressure pulses
-
- 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
- F04C2/30—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members
- F04C2/34—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members
- F04C2/356—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the outer member
-
- 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
- F04C13/00—Adaptations of machines or pumps for special use, e.g. for extremely high pressures
- F04C13/001—Pumps for particular liquids
-
- 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
- F04C2220/00—Application
- F04C2220/24—Application for metering throughflow
Definitions
- the present invention concerns a volumetric pump capable of transferring fluids from an inlet to an outlet at accurately controlled flow rates without pulsations or sudden gushes of fluid spurting out through the outlet.
- the delivery of fluid to the outlet can be controlled at a constant flow rate, dV / dt, during a whole transfer operation or, alternatively, the flow rate may be varied in a controlled manner, and even interrupted for periods of time.
- Fluids of viscosities varying from highly fluid to highly viscous can be used with the volumetric pump of the present invention, with a very limited generation of shear stresses allowing the reduction of wear rate of pump parts as well as the preservation of the integrity of unstable fluids, such as sols, gels, or even liquids contained in a membrane, such as egg yolk. Thanks to its precision and versatility the volumetric pump of the present invention can be used in a variety of applications including, albeit not restricted to, 3-D printing heads, medical fluids delivery systems, metering heads in industrial production lines of products requiring an accurate dosing and/or mixing of fluid components in industries such as pharmaceutical, cosmetics, food, paper, building, and the like.
- Positive displacement pumps are volumetric pumps. They include rotary-type positive displacement pumps, reciprocating-type positive displacement pumps, and linear-type positive displacement pumps. Rotary-type positive displacement pumps (hereinafter referred to as rotary pumps) move fluid using a rotating mechanism that creates a vacuum that captures and draws in the liquid in transfer volumes, transporting the captured fluid towards the outlet by rotation of the rotating mechanism.
- rotary pumps move fluid using a rotating mechanism that creates a vacuum that captures and draws in the liquid in transfer volumes, transporting the captured fluid towards the outlet by rotation of the rotating mechanism.
- Syringes do not generate pulsations, but they are ill-fitted for continuous dispensing applications.
- rotary-type positive displacement pumps can be used in a continuous mode over time, but generally generate small variations of flow rate in time, forming pulsations in the output of the pump.
- the amplitude of the pulsations can be reduced by coupling a pulsation damper to the rotary pump, but pulsation dampers increase the cost of the pumping system, they are bulky, and pulsations are not eliminated, but merely dampened at the expenses of a loss in accuracy of the volumetric flow rate.
- US1892217A filed in 1931 describes a“gear mechanism adapted to be used as a [rotary] pump,” still in use to date and sometimes referred to as“Progressing Cavity Pump.”
- This pump combines a rotation and a translation of a single screw type rotor into a matching threaded sleeve having an extra thread compared to the rotor.
- This type of pumps reduces the problem of pulsations associated with rotary pumps, but the intricate structure of this pump increases the complexity and costs in manufacturing and maintenance and reduces the freedom of design required for adapting to different pumping configurations. Universal joints are required, and the rotor and the sleeve are complex to manufacture, with tight tolerances for proper sealing.
- This type of pump is also limited to one geometry that has a much higher space claim than any other pumps, especially in the axial direction.
- WO2017055497A1 describes a pump having a rotor that is rotatable about a rotation axis and comprises a rotor hub and a rotor collar that extends from the rotor hub in the radial direction and encircles it in an undulating manner. As the hub rotates, so does the collar forming a sinusoidal wave oscillating in the axial direction.
- a sleeve consisting of a portion of a straight cylinder closed at its ends forms with the disc and hub the cavities for transporting fluid.
- a vane pinching the disc is rotatably fixed and rides over the disc, which rotation drives a reciprocating translation of the vane along the axial direction of the rotor. The vane is used to prevent recirculation of the fluid from the outlet side to the inlet side.
- US2754762 and US2609754 describe volumetric pumps comprising two cams mounted on a common axle of rotation with an angular offset.
- Flowrate fluctuations increase with increasing value of the radius ratio, (R L - n ) / R L .
- the present invention proposes a volumetric pump suitable for continuously or intermittently delivering a fluid at an accurately controlled flow rate over time.
- the nominal flowrate fluctuation can be reduced to below ⁇ 0.05%, and even down to zero.
- the pump of the present invention reduces shear stresses in the fluid compared with other rotating pumps, and is of simple construction, allowing for cheaper manufacturing conditions.
- the geometries and dimensions of the pumps of the present invention can be varied to adapt to the specific requirement of each application.
- the present invention concerns a volumetric pump comprising a chamber having a chamber breadth, B, comprising an inlet volume provided with an inlet and an outlet volume provided with an outlet, the inlet volume being separated from the outlet volume by m pumping systems enclosed in the chamber, with m e N, and m > 1 , each pumping system comprising, • at least a portion of one of m / k radial cams with k £ N and k 1 0, comprising at least two noses, i.e., each radial cam comprises p > 2 k noses, wherein all of the m / k radial cams are mounted on an axis of rotation, Zl, parallel to the chamber breadth, B, such that the radial cam and chamber can rotate relative to one another about the corresponding axis of rotation, Zl, and
- a vane or vane portion movingly mounted in the chamber such as to keep permanent contact with a circumferential track (3t) of the radial cam or cam portion, and together with the radial cam or cam portion, permanently fluidly separating the inlet volume from the outlet volume,
- a sum of volumetric displacements, Di, of the m pumping systems generated by the rotation of the m radial cams is constant for any azimuthal angle, a, of rotation about the axis of rotation, Zl, within a tolerance of not more than ⁇ 1%, preferably not more than ⁇ 0.5%, more preferably not more than 0.2%:
- volumetric displacement, Di dVi / da, is defined as the volume of fluid displaced through the cross-sectional opening per unit angle of rotation (in radians) of one pumping system.
- the chamber comprises first, and second lateral walls separated by a joining wall of breadth, B, wherein
- • comprise a circumferential track (3ti) defined by a track profile joining the first and second peripheral rims, and defined by a distance, Ri(a, z) Rli(a) + ri(z), from the axis of rotation, Zl (wherein z is measured along the axis of rotation, Zl).
- each of the r consecutive external cams or s internal cams are separated from one another by (r- 1) or (s - 1) dividing walls (3wi), each dividing wall being normal to the axis of rotation, Zl, and comprising at least a circular ring having an outer radius and an inner radius, wherein for external cams, the outer radius is equal to the largest of the nose radii, Rmi, Rln(i+l), and the inner radius is equal to or smaller than the smallest of the belly radii, Rrbi, Rlb(i+l), of two adjacent radial cams (3i, 3(i+l)) separated by said dividing wall, and for internal cams the outer radius is equal to the largest of the belly radii, Rrbi, Rlb(i+l), and the inner radius is equal to or smaller than the smallest of the nose radii, Rmi, Rln(i+l), of said two adjacent radial cams (3i, 3(i+l)),
- outer circumferential tracks which are optionally provided with an outer dividing wall separating the outer circumferential tracks from the first or second lateral walls
- each of the m vanes or m vane portions comprises a leading edge having a vane profile mating the track profile of the corresponding circumferential track, wherein said m vanes or m vane portions are radially mounted in the chamber fluidly separating the inlet volume from the outlet volume, such as to radially translate while the leading edge keeps at all time a sealed contact with the corresponding circumferential tracks of the m radial cams, each vane or vane portion having a height, di, at least equal to the absolute value of the difference between the nose radius Rlni and the belly radius Rlbi, of the corresponding radial cam (di >
- each of the m pumping systems comprises a liner or a liner portion, rigidly coupled to the chamber and circumscribing a corresponding radial cam, wherein each of the m liners and/or liner portions,
- • has a geometry of revolution, about the axis of rotation, Zl, of largest radius substantially equal to and slightly larger than the largest value of Ri(a, z) at the level of a nose of the corresponding circumferential track, and having a liner profile extending parallel to the axis of rotation, Zl, which mates the track profile of the corresponding circumferential track, such that the m radial cams can rotate about the corresponding axis of rotation with respect to the corresponding m liners,
- volumetric displacement, Di of each pumping system generated by the rotation of the corresponding radial cam is for any azimuthal angle, a, of rotation about the axis of rotation, Zl : Rlnf — Rif (a) bi
- the volumetric pump comprises,
- the volumetric pump comprises,
- the volumetric pump comprises,
- each radial cam comprises an odd number p of noses
- each radial cam comprises an even number p of noses
- the r external radial cams or s internal radial cams have the same periodicity p, with an azimuthal offset of p / p rad.
- the m cams are identical in geometry.
- the peripheral edges of the m cams can be symmetric at the level of theirs noses, so that the direction of rotation can be inverted while maintaining the same stress levels on the vanes while yielding the same flowrate as a function of absolute value of the rotation rate,
- the volumetric pump can comprise more than one inlet, opening into the inlet volume. Similarly, it may comprise more than one outlet, opening out of the outlet volume, and/or comprise an outlet which is in fluid communication with a manifold comprising more than one outlet.
- the relative rotation of the radial cam and chamber can be according to any of the following configurations:
- the m radial cams are static, and the chamber rotates about the axis of rotation, Zl, together with the vanes or vane portions, and liners or liner portions, or
- the m radial cams rotate about the axis of rotation, Zl, at a velocity, col, and the chamber rotates about the axis of rotation, Zl , together with the vanes or vane portions, and liners or liner portions at a velocity, co2, wherein col 1 co2, and col and co2 1 0.
- volumetric pumps can be assembled to form a high accuracy mixing pump, comprising at least two volumetric pumps as defined supra, lodged in a common chamber, wherein,
- each volumetric pump comprises a separate inlet and inlet volume fluidly separated from the inlets and inlet volumes of the other volumetric pumps, and
- Figure 1 shows the principle of combining complementary pulsed flowrates to yield a constant overall flowrate over time at a given rotation rate, co,
- Figure 2 shows various external radial cams, (a)-(c) perspective views, (d)-(f) cut views.
- Figure 5 shows two embodiments of mixing pumps comprising more than one inlets.
- Figure 6 shows one way of designing a pair of identical complementary cams.
- Figure 7 shows examples of external cams comprising a dwell region.
- the present invention concerns a volumetric pump of the type of rotary positive displacement pumps comprising a chamber (1) having a chamber breadth, B, measured along a direction parallel to an axis of rotation, Zl, comprising an inlet volume provided with an inlet and an outlet volume provided with an outlet and wherein the inlet volume is separated from the outlet volume by m pumping systems enclosed in the chamber, with m e hi, and m > 1. All the pumping systems share the axis of rotation, Zl.
- Each pumping system comprises,
- a vane or vane portion movingly mounted in the chamber such as to keep permanent contact with a circumferential track (3t) of the radial cam or cam portion, and together with the radial cam or cam portion, permanently fluidly separating the inlet volume from the outlet volume,
- the geometry of the radial cams of the volumetric pump of the present invention is defined such that a sum of the volumetric displacements, Di, of the m pumping systems generated by the rotation of the m radial cams is constant for any azimuthal angle, a, of rotation about the axis of rotation, Zl, within a tolerance of not more than ⁇ 1%, preferably not more than ⁇ 0.5%:
- the volumetric displacement, Di dVi / da, is defined as the volume of fluid displaced through the cross-sectional opening per unit angle of rotation (in radians) of one pumping system
- each pumping system comprise,
- a corresponding radial cam (31) or a cam portion shared with (k - 1) other pumping system(s) (3i, i 2 to m), rigidly coupled with the respective cam or cam portion of the other (m - k) pumping systems, mounted on the axis of rotation, Zl, such that the radial cams or cam portions of the m pumping systems and the chamber can rotate relative to one another about the axis of rotation, Zl, and having a geometry defined as follows: o first and second peripheral rims (3ri, 3li) separated from one another by a cam breadth, bi, measured parallel to the axis of rotation, Zl, and defining first and second planes normal to the axis of rotation, Zl, said first and second peripheral rims having a periodicity of p, defining p identical sectors of central angle 2p / p rad, and having a radius, Rri, and Rli, extending from the corresponding axis of rotation, Zl, to the first
- a vane (5i) or vane portion movingly mounted in the chamber such as to keep permanent contact with the circumferential track of the radial cam or radial cam portion, and together with the radial cam or radial cam portion, permanently fluidly separating the inlet volume from the outlet volume,
- o has a geometry of revolution, about the axis of rotation, Zl, has a breadth substantially equal to the cam breadth, bi, and has a liner profile extending parallel to the axis of rotation, Zl, mating the circumferential track profile at the level of a nose of the corresponding radial cam or cam portion, such that the corresponding radial cam can rotate about the axis of rotation with respect to the liner,
- o extends from an upstream end (7u) located in the inlet volume, to a downstream end (7d) located in the outlet volume, and has a peripheral length equal to or larger than the length of a circular arc comprised between two consecutive noses of the corresponding radial cam,
- a cross-sectional opening comprised on a downstream plane, Pi, and bounded between the corresponding circumferential track and the liner and having an area Ai.
- the downstream plane, Pi is a radial plane comprising the axis of rotation, Zl, and passing by a point of the downstream edge of the liner and/or liner portion which is located furthest away from the outlet.
- the area Ai varies with the azimuthal angle between 0, when a nose is level with the downstream end of the liner (i.e., intersects the downstream plane), and
- a radial cam or cam portion When a radial cam or cam portion has a first nose level with the upstream end of the corresponding liner, fluid present in the inlet volume is carried in a volume created by the rotation about the axis of rotation, Zl, of the radial cam, which is comprised between the circumferential track and the corresponding liner.
- a transport chamber is thus formed which capacity evolves as a function of the azimuthal angle, a, of rotation and reaches a maximum capacity when the first nose and an adjacent downstream nose separated by a belly are all located within the peripheral length of the corresponding liner.
- the fluid present in the transportation chamber is dispensed into the outlet volume through the cross-sectional opening comprised between the circumferential track and the liner.
- the flowrate, Ql of a first pumping system formed by a radial cam, a liner, and a vane (or portions thereof) and rotating at a constant rotation rate, co, varies with time creating periodical pulsations of fluid flow.
- the gist of the present invention is to combine m pumping systems, each characterized by its own periodical pulsations, in such a way that the periodical pulsations of the (m - 1) pumping systems compensate the periodical pulsations of the first pumping system, to yield an overall constant flowrate with time, without (or very limited) pulsation. This result can be achieved as described below.
- the flowrate pulsations referred to in the present document are nominal pulsations or theoretical pulsations, which are calculated as a function of the geometries of the various radial cams and their relative positions. It is clear that the reduction to zero of the nominal flowrate pulsations may lead in practice to a certain level of pulsations of an actual flowrate measured on an actual pump manufactured based on the geometry yielding a zero -pulsation nominal flowrate, since the calculation to determine the nominal flowrate pulsations of a given volumetric pump neglects frictional losses and assumes perfect sealing between moving parts of the pump, which in practice cannot be achieved. This is common practice in the art and in line with the literature.
- the gist of the present invention is to combine two or more (m >l) pumping systems such that the sum, of the fluid flow rates delivered to the outlet volume by a synchronized rotation of the m radial cams of the m pumping systems is constant at any time, at a given rotation rate, co,
- Equation (2) Equation (2)
- a is the azimuthal angle at a given time at the rotation rate, co, of the cams (3i) with the azimuth reference taken for each cam (3i) e.g., at the initial relative position of this cam and the corresponding downstream plane Pi.
- a height of the cross-sectional opening measured radially varies from zero, when a nose of a radial cam intercepts the downstream plane, Pi, to a maximum value when a belly of the radial cam intercepts the downstream plane.
- the centroid (or geometric centre) of a plane figure is defined as the arithmetic mean position of all the points in the shape.
- the volumetric displacement, Di can be expressed as follows:
- Equation (3) can be simplified when considering specific geometric configurations of the radial cams.
- a radial cam geometry of the present invention is fully defined by three (3) constant: dimensions Rlni, Rlbi, bi, and by two (2) variation laws: Rli(a) and ri(z).
- the Rli(a) law can be expressed as,
- Rli d) Rlrii - ( Rlrii - Rlb ⁇ .
- U ⁇ a) Ui(a) is a continuous and smooth function comprising no comer point, and periodically varying between 0 and 1 with a period 2p / p (p > 1), such that the peripheral rim profile Rli(a) varies periodically between p nose radii, Rlni, and p belly radii, Rlbi.
- a function is defined herein as comprising a comer point if the function is not differentiable at that point. In other words, the smooth function Ui(a) must be differentiable at all points.
- Ui(a) Ui(a)
- This geometry yields non-oriented cams which give similar outputs regardless of the direction of rotation, because the rising parts of the flowrate curves illustrated in the diagrams of Figure 1 are symmetrical with the descending parts of said curves.
- Other typical smooth functions traditionally used in cam manufacturing that can be used in the present invention are cycloidal functions or second or third harmonic functions.
- This geometrical simplification condition can also simplify the equations.
- Another geometrical simplification condition can consist of designing radial cams to have two-by-two flow complementary geometries (i.e., radial cams coupled in pairs to yield a constant flow rate).
- the radius, Rli(a), of the peripheral rim of every second cam (3i) i.e., the index i is an even natural number
- the radius, Rl(i-l)(a), of the previous cam (3(i-l)) j.e., the index i is an odd natural number
- the first radial cam (31) which is defined as the reference cam, must first be characterized by defining values for the constant dimensions Rlnl, Rlbl, bl, and by defining the variation laws Rll(a) and rl(z). Care should be taken when defining Rlnl, Rlbl, and Rll(a), that at any one point of the curve thus defined, the normal to the tangent to the curve at said any one point preferably does not form an angle of more than a predefined value with the radius joining said any one point to the rotation axis, Zl.
- the predefined value is preferably 30°. In case the leading edge of the vane has a rounded profile, the predefined value can be higher, of the order of up to 45°. This angle corresponds to the so-called pressure angle formed between the vane, which is oriented radially, and the circumferential track. A large value of the pressure angle generates high levels of stress between the vane and the radial cam.
- the derivative (tangent) of the curve can be calculated and the pressure angle determined, thus defining the ranges of values of Rlnl and Rlbl satisfying the predefined conditions on the pressure angle.
- Equation (3) The volumetric displacement, D 1 , of the first radial cam (31) is defined by Equation (3), as,
- Rln2 and of b2 must be predefined.
- b2 can be arrived at by predefining a value of Rlb2 and expressing b2 as a function of Rlb2.
- the former option i.e., predefined values of Rln2 and b2
- the latter option i.e., predefined values of Rln2 and Rlb2
- the value of b2 can thus be determined from the predefined values of Rln2 and Rlb2.
- the design of a pair of complementary cams has been discussed supra. The same method can be used for the specific case discussed supra of a series of m cams complementary two-by-two.
- an alternative manner of designing m complementary cams, with m > 2 is described using a set of (m - 1) reference cams.
- Another preferred option is to design a set of m radial cams (m > 2) with geometries that are flow complementary by determining the geometry of the m th cam on the basis of the predefined geometries of the (m - 1) first cams which are used as reference cams. This can be achieved as described supra for a pair of complementary cams, simply by considering the (m - 1) first cams as one“aggregate” reference cam forming the reference cam as described supra.
- the geometry of the m th cam can be determined using Equation (4b) as described supra, taking the aggregate reference cam as the first cam defined in the preceding section.
- the method for designing a pair of complementary cams presented above can generate complementary cams that are identical only in very specific cases, which can be complex to determine and which probability to arrive at by trials and errors is very low. Designing a pump with all radial cams having the same geometry is, of course, very advantageous in terms of manufacturing, production cost, and management of spare parts for maintenance and repair. A method is presented in continuation for designing a pair of complementary cams which have the same geometry.
- the corresponding vane (5i) When rotating a radial cam (3i) in a direction, the corresponding vane (5i) translates radially away from the axis of rotation when a leading edge of the vane follows the corresponding circumferential track from a belly to an adjacent nose of the cam - the vane rises — , and translates towards the axis of rotation, Zl, when the vane travels from the nose to a next belly - the vane descends.
- the resulting complementary cam will most probably have a different geometry than the reference cam.
- a pair of complementary cams having same geometry can be obtained quite easily from the thus obtained pair of complementary, albeit differing cams as follows.
- pumps according to the present invention can have various configurations.
- pumps according to the present invention can have various configurations.
- the radial cams can be external cams (cf. Figure 1(a) - 1 (d), 1 (i), and l(j)) or internal cams (cf. Figure l(e)-(h)).
- the cams can be symmetrical, as identified by the label‘(S)’ in Figure l((a), l((d), 1(f), 1(g), and l(j), yielding dV / dt(a)-curves which are symmetrical and allowing the cams to rotate in both directions with identical stress on the vanes, or asymmetrical, as identified by the label‘(NS)’ in Figure 1(b), 1(c), 1(e), 1(h), and l(i).
- the second cam (32) has a geometry fully determined by the geometry of the first cam (31) such that the respective flowrates produced by the rotation of one cam has fluctuations that complement the fluctuations of the other cam to yield a total flowrate which is constant (i.e., with no fluctuation).
- the flowrate produced by the rotation of the third cam (33) must be the complementary of the sum of flowrates produced by the rotations of the first and second cams (31-32) which, together form an aggregate reference cam, to yield a total flowrate which is constant (i.e., with no fluctuation).
- the chamber comprises first, and second lateral walls separated by a joining wall of breadth, B
- the same chamber of breadth, B encloses m volumetric pumps formed by r external cams or s internal cams, each cam being divided into k portions.
- k portions of a same radial cam are physically separated from one another by k vanes (portions) and appropriate separation walls, preferably forming an integral part of the liners.
- a longer dwell zone inevitably reduces the capacity of the transfer volumes and therefore reduces the output of the pump.
- the area of friction between the dwell regions and corresponding liners increases with the length of the dwell region, thus increasing abrasion rate.
- the periodicity p is given herein the usually accepted meaning in mathematics of the pulsation of a periodic function.
- a periodic function is a function that repeats its values in regular intervals or periods of 2p / p radian. The most important examples are the trigonometric functions, which repeat over intervals of 2p radians.
- the period is a measure of a function "repeating" itself.
- each of the m radial cams comprises a circumferential track (3t) comprising p track noses, defined as the portions of the circumferential track (3t) comprised between the segments of central angle, a n on the 2 peripheral rims corresponding to a nose defined by radii Rlni & Rmi.
- the track nose can be a surface defining an area in case the segments corresponding to a peripheral rim nose extend over a range of values of the central angle, a n , as illustrated e.g., in Figures 2(b) and 7.
- Such track noses forming a surface having an area are called dwell regions (3id), which are circular portions of the circumferential track.
- Radial cams comprising dwell regions may be advantageous for sealing at the level of the liners by a close fit with no contact to limit wear and energy losses by increasing the sealing area.
- the liners are described more in details below.
- peripheral dwell regions (3id) are circular, defined by a left peripheral rim section of radius Rlni and a right peripheral rim section of radius, Rmi (not shown in Figure 7).
- Peripheral dwell regions (3id) defining track nose surfaces must be accompanied by corresponding circular belly regions defined by a left peripheral rim section of radius Rlbi and a right peripheral rim section of radius, Rrbi (not shown in Figure 7), of same central angle as the dwell region for the following reason.
- each of the r consecutive external cams and or of the s consecutive internal cams are separated from one another by (r - 1) or (s - 1) dividing walls (3wi), each dividing wall being normal to the axis of rotation, Zl, and comprising at least a circular ring of outer radius equal to the largest of the nose radii, Rmi, Rln(i+l), and of inner radius equal to or smaller than the smallest of the belly radii, Rrbi, Rlb(i+l), of two adjacent radial cams (3i, 3(i+l)) separated by said dividing wall.
- the first and second outer circumferential tracks are defined as the circumferential tracks which are adjacent to a single neighbouring circumferential tracks; In other words, they are the circumferential tracks which are adjacent to the first and second lateral walls of the chamber.
- the first and/or the second outer circumferential tracks can optionally be provided with an outer dividing wall (3owl, 3ow2) separating the outer circumferential tracks from the first or second lateral walls of the chamber.
- the outer dividing walls (3owl, 3ow2) are not essential but help enhancing the fluid tightness between a radial cam and a lateral wall of the chamber with cost effective dimensions tolerances.
- the pump must comprise m vanes (5i) or vane portions (5i), each one associated with one circumferential track.
- Two vane portions can be combined for forming a single element.
- two vane portions can be combined to form a single element in a pump comprising a single internal cam shared by two pumping systems, with the two corresponding vane portions being diametrically opposed to each other and optionally joined together by a section that can deform elastically (cf. Figure 1(g)).
- Each vane (5i) or vane portion comprises a leading edge and is mounted in the chamber so as to translate linearly back and forth along a vane radial plane including the axis of rotation, Zl, as the corresponding cam (portion) (3i) rotates and the leading edge of the vane (portion) keeps permanent contact with the rotating circumferential track (3ti).
- the vanes (portions) must fluidly separate the inlet volume from the outlet volume.
- the leading edge of each vane must have a geometry mating the geometry of the corresponding circumferential track profile.
- the leading edge is furthest from the axis of rotation when contacting the circumferential track at peripheral nose surface (i.e., at a nose of the cam) as illustrated in Figure 3(a) and is closest thereto when contacting the circumferential track at a belly as illustrated in Figure 3(b).
- a sealed contact can thus be maintained during the rotation of the radial cams relative to the chamber, and the inlet volume is thus fluidly separated from the outlet volume at any time.
- each vane or vane portion must have a height, di, measured radially at least equal to the absolute value of the difference between the nose radius Rlni and the belly radius Rlbi, of the corresponding radial cam (di >
- the concave circumferential tracks in some embodiments of the present invention allow using cylindrical vanes with a round end tip (ball end). This presents the advantage of better cleanability and higher resistance to abrasion by presenting no sharp edges, and increased sealing efficiency around the vanes at casing interface (plunger/piston type of sealing).
- the liners define with the circumferential tracks transfer volumes reaching the outlet volume in a synchronized fashion summing up in a constant flowrate.
- m liners (7i) and/or liner portions (7i) each one being associated with a circumferential track are rigidly coupled to the chamber and have the following geometry.
- the liner profile mates the circumferential track profile is meant that both profiles share the same function, Ri(a, z), of the distance to axis of rotation, Zl, with the radius of the liner being slightly larger than the radius of the circumferential track, within tolerances, to allow rotation of the cam relative to the corresponding liner.
- Figure 2(d)-(f) show some examples of simple circumferential track geometries which circumferential track profiles are mated by the geometries of the corresponding liners (7i).
- Figure 2(d) shows a flat circumferential track
- Figure 2(e) shows a convex circumferential track
- Figure 2(f) shows a concave circumferential track, all mated by the corresponding liners (7i).
- each liner is equal to or larger than the length of a circular arc comprised between two consecutive noses of the corresponding radial cam.
- each liner In case of a radial cam comprising dwell regions of central angle, an, each liner must have a peripheral length of at least (2p / p - an) Rni(z).
- Each radial cam is flanked on either side thereof by a side wall.
- the side wall can be a dividing wall (3wi), an outer lateral wall (3owi), or a lateral wall of the chamber.
- an incipient open transport chamber (6i) forms and fills with fluid present in the inlet volume.
- a closed transport chamber is formed defined as the volume comprised between the circumferential track and the liner and flanked on either side by a side wall.
- the closed transport chamber is fluidly separated from both inlet and outlet volumes.
- the first nose reaches the downstream end of the liner, and the transport chamber opens onto the outlet volume.
- the transport chamber is therefore never in fluid communication with both inlet and outlet volumes simultaneously.
- the cross-sectional opening, Ai is formed by the intersection of a transport chamber with the downstream radial plane (which intersects the downstream end of the liner).
- the cross-sectional openings have an area, Ai, on the downstream plane, Pi, defined as the radial plane comprising the axis of rotation, Zl, and passing by a point of the downstream edge of the corresponding liner and/or liner portion which is located furthest away from the outlet. Said cross-sectional opening is bounded, on the one hand,
- a liner has the nose radius, Rn, of the external cam it is associated with, it means that the value, Rn(liner), of the liner is slightly larger by a tolerance, d, than the value, Rn(cam), of the external cam, such that the external cam and liner can rotate relative to one another.
- the tolerance, d should be sufficiently large for allowing the relative movement of the two corresponding elements without excessive friction, and sufficiently small to form a seal conferring a sufficient fluid tightness to the contact area between the two elements.
- the relative positions of the downstream end of the liners with respect to a set of complementary cams and the distances separating the downstream end of the liners from the corresponding vanes are key to obtain the synchronized effect of complementary sum of flowrates.
- the relative positions of the upstream ends of the liners in the inlet volume can also be optimized to sum up to an overall constant flowrate filling the transfer volumes of each pumping system in a synchronized manner to prevent any fluctuation in the inlet volume before transportation of the fluid towards the outlet volume. This can reduce the stress on the piping system connected to the inlet.
- a reversible pump must have liners of same peripheral length to offer the same complementary sum of flowrates in both directions of rotation.
- the azimuthal distance separating the downstream end of a liner from the corresponding vane or vane portion must be equal for all pumping systems
- the volumetric pump comprises,
- the volumetric pump comprises,
- An internal cam defines an inner cavity wherein the peripheral edge is an inner edge of the internal radial cam of depth, W, and is centred on the axis of rotation, Zl, of radius varying p-periodically from a lowest value corresponding to the nose radius, Rn, to a highest value corresponding to the belly radius, Rb.
- a pump according to the present invention comprising internal cams is illustrated in Figures l(e)& 1(f).
- Two vanes (51, 52) contact the first and second circumferential tracks to fluidly separate the inlet volume from the outlet volume.
- First and second liners (71, 72) centred on the axis of rotation, Zl, contact within a tolerance, d, the peripheral nose surfaces of the first and second circumferential tracks.
- the circumferential tracks (3 lt, 32t) of the first and second internal cams (31, 32) form with the corresponding liners (71, 72) a transport chambers (61, 62) which, upon rotation of the internal cams, transports fluid from the inlet volume towards the outlet volume
- the internal cavity defined by the internal cam is fluidly divided in two halves-cavities by two translating vane portions (51, 52) radially and coaxially aligned.
- Each half-cavity is provided with an inlet volume including an inlet (lu) and an outlet volume including an outlet (ld) and by two liners (71, 72) which geometry mating the circumferential tracks of the internal cam fluidly separates the inlet volume from the outlet volume.
- Each of the two half cavities is provided by its own pumping system formed by a liner and one half of the internal cam, defined by the vane portions.
- the flowrate out of the pumping system associated with a first half-cavity is complementary with the flowrate out of the pumping system associated with a second half-cavity, yielding a constant overall flowrate.
- the volumetric pump of the present invention can also be used for mixing two or more fluids (Fl, F2, 7) with highly accurate mixing ratios and homogeneity.
- the inlet volume can be provided with more than one inlets, each in fluid communication with a source of fluid, Fl, F2, to be mixed and transferred to the outlet.
- the pump comprises q inlets (1 lu, 2lu, 3 lu), each inlet being in fluid communication with a corresponding inlet volume, the q inlet volumes being fluidly separated from one another.
- the outlet volumes of the q pumping systems form a single outlet volume.
- the q pumping systems can deliver fluids at an accurately controlled flowrate, a homogeneous mixture having the desired mixing ratio reaches the outlet volume and the outlet (3d).
- Mixing ratios can be controlled by varying the width, W, of the q inlet volumes and cams of the q pumping systems. Alternatively, or concomitantly, the rotation rate of the q pumping systems can be varied relative to one another.
- the volumetric pump of the present invention can also comprise several outlets and/or an outlet can be in fluid communication with a manifold comprising more than one outlets.
- This embodiment can be advantageous in case of printing or depositing a paste following several parallel lines which can be curvilinear in coating applications or in the food industry, or for filling phials with a controlled volume of fluid, e.g., in the pharmaceutical or cosmetic industries, and the like.
- the principle of radial cam rotary-type positive displacement pumps according to the present invention is based on the rotation of a number of radial cams relative to the chamber and liners.
- the m radial cams can rotate about their respective axis of rotation, and the chamber can be static.
- the m radial cams can be static, and the chamber can rotate about an axis of rotation, together with the corresponding vanes or vane portions, and liners or liner portions.
- both radial cams and chamber can rotate at different rotation rates, in same or different directions of rotation. Having both radial cams and chamber rotating in the same rotating direction allows an accurate control of very low values of flowrates.
- the one or more inlets and/or the one or more outlets can be oriented normal to the axis of rotation, Zl, opening at the joining wall of the chamber as shown in Figures 1, 4, and 5. Alternatively, they can be oriented parallel to the axis of rotation, Zl, opening at a lateral wall of the chamber as shown in Figure 5(b).
- Table 1 lists a number of examples of pumps, characterized by the parameters, m, r, s, and p.
- Table 1 Examples of volumetric pumps according to the present invention.
- the volumetric pump of the present invention is particularly adapted for applications where shear stresses on the transported fluid should be as low as possible.
- Low shear stresses preserve shear-sensitive fluids and preserve the internal components of the pump against the aggression of abrasive fluids or solid particles suspended in the fluid.
- the pump minimizes generation of shear stresses to the fluid by excluding rotors interacting in contra-rotation, and by presenting no sharp angle normal to the flow of the fluid.
- the stresses the flowing fluid is exposed to are reduced at the interfaces and in the piping system too.
- the volumetric pump of the present invention is also particularly adapted for applications where cleaning is critical, like sanitary applications or with fast setting/curing materials which could block the moving parts if not removed quickly when the pump is stopped.
- the pump can be designed to be Clean In Place (CIP) or Steam In Place (SIP).
- CIP Clean In Place
- SIP Steam In Place
- this volumetric pump is ideal for dosing and specially controlled extrusion applications such as 3D printing of fluids and pastes.
- volumetric pump according the present invention can be used in anyone of the following applications.
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Abstract
Description
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Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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EP18184949 | 2018-07-23 | ||
PCT/EP2019/069755 WO2020020864A1 (en) | 2018-07-23 | 2019-07-23 | Volumetric pump with flow complementary radial cams |
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EP3827172A1 true EP3827172A1 (en) | 2021-06-02 |
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EP19742214.0A Withdrawn EP3827172A1 (en) | 2018-07-23 | 2019-07-23 | Volumetric pump with flow complementary radial cams |
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WO (1) | WO2020020864A1 (en) |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
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US1892217A (en) | 1930-05-13 | 1932-12-27 | Moineau Rene Joseph Louis | Gear mechanism |
US2013397A (en) * | 1930-08-26 | 1935-09-03 | Landis Tool Co | Hydraulic motor and method for making the same |
US2609754A (en) | 1948-09-14 | 1952-09-09 | Prendergast Charles Scott | Pump and motor |
US2717555A (en) | 1949-06-21 | 1955-09-13 | John N Hinckley | Engine for pumping and the like having multiple rotors and swinging arms |
US2845872A (en) * | 1953-09-16 | 1958-08-05 | Bendix Aviat Corp | Cam pump |
US2754762A (en) | 1954-03-05 | 1956-07-17 | Hamilton Gordon | Pumps and motors |
US9470228B2 (en) * | 2012-07-03 | 2016-10-18 | Brian J. O'Connor | Multiple segment lobe pump |
US9752571B2 (en) * | 2012-07-03 | 2017-09-05 | Brian J. O'Connor | Multiple segment lobe pump |
DE102015116768A1 (en) | 2015-10-02 | 2017-04-20 | Watson-Marlow Gmbh | pump |
-
2019
- 2019-07-23 EP EP19742214.0A patent/EP3827172A1/en not_active Withdrawn
- 2019-07-23 WO PCT/EP2019/069755 patent/WO2020020864A1/en unknown
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