US20120308412A1 - Diaphragm Metering Pump Device for Medical Use - Google Patents
Diaphragm Metering Pump Device for Medical Use Download PDFInfo
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- US20120308412A1 US20120308412A1 US13/518,376 US201013518376A US2012308412A1 US 20120308412 A1 US20120308412 A1 US 20120308412A1 US 201013518376 A US201013518376 A US 201013518376A US 2012308412 A1 US2012308412 A1 US 2012308412A1
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- Prior art keywords
- diaphragm
- pressure
- pumping
- annular
- pumping chamber
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/142—Pressure infusion, e.g. using pumps
- A61M5/14212—Pumping with an aspiration and an expulsion action
- A61M5/14224—Diaphragm type
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B43/00—Machines, pumps, or pumping installations having flexible working members
- F04B43/0009—Special features
- F04B43/0054—Special features particularities of the flexible members
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
- A61M5/142—Pressure infusion, e.g. using pumps
- A61M5/145—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons
- A61M5/14586—Pressure infusion, e.g. using pumps using pressurised reservoirs, e.g. pressurised by means of pistons pressurised by means of a flexible diaphragm
Definitions
- the present invention relates to a metering pump device for medical use comprising a pumping chamber, an annular pumping diaphragm the outer edge of which is secured to the said pumping chamber and the inner edge of which is secured to a central drive part that is more rigid than the said diaphragm, able to be displaced parallel to itself between an extreme return position and an extreme displacement position in its expulsion stroke and its intake stroke, respectively, these two positions lying one on each side of the plane containing the outer edge of the said annular diaphragm, the said pumping chamber comprising an inlet valve and an outlet valve which are respectively opened by a reduced pressure and by a raised pressure in the pumping chamber as a result of the movements of the said annular pumping diaphragm, the intake stroke of the said diaphragm resulting from the energy accumulated by the elastic deformation of the diaphragm during its expulsion stroke.
- the outlet valve of the pump has to provide safety against a free flow of liquid under a certain pressure, which is typically that of the column of liquid between a pouch of perfusion liquid and the pump, or the pressure resulting from accidental pressure applied to the pouch of liquid.
- a certain pressure typically that of the column of liquid between a pouch of perfusion liquid and the pump, or the pressure resulting from accidental pressure applied to the pouch of liquid.
- the pumping diaphragm has to be able to withstand the working pressure, which is made up of a pressure to open the outlet valve that has to remain closed up to a pressure that is determined by safety standards, of a pressure drop in the downstream pipe and of a service pressure at the end of the downstream pipe.
- the pumping diaphragm has to be able to take in the liquid by moving from its extreme displacement position to its extreme return position creating enough of a reduced pressure in the presence of the pressure drop in the upstream and downstream pipes of the pumping device and of the pressure threshold of the inlet valve.
- the pumping diaphragm could be connected to the actuator for a two-way drive.
- a two-way drive would make the single use more complicated and therefore more difficult to manufacture and would make it more difficult to fit into the drive device.
- This method of driving also allows great precision in the control of the position of the diaphragm, and therefore great precision in the flow rate.
- the subject of the present invention is a metering pump device for medical use according to Claim 1 .
- FIG. 1 is a schematic general arrangement of the metering pump device
- FIG. 2 is a diagram illustrating a typical operating pumping range using a flat pumping diaphragm
- FIG. 3 is a cross section through a pumping diaphragm according to the invention intended to be connected to a pumping chamber;
- FIG. 4 is a pressure-displacement diagram for a pumping device using the diaphragm of FIG. 3 ;
- FIG. 5 is a comparative pressure-displacement diagram of a pumping device using a flat diaphragm with the same dimensional ratios as the diaphragm of FIG. 3 ;
- FIG. 6 is a diagram showing the pressure sensitivity of the diaphragm of FIG. 3 ;
- FIG. 7 is a comparative pressure-sensitivity diagram for the flat diaphragm of FIG. 5 ;
- FIG. 8 is a diagram of the diaphragm of the pumping device that forms the subject of the invention, showing the characteristic dimensions the dimensional ratios of which will be discussed further in the description.
- the metering pump device that forms the subject of the invention is illustrated very schematically in FIG. 1 , given that it is the elastically deformable pumping diaphragm 1 , and the geometry and structure thereof, which constitute the innovative part of this invention.
- this device comprises a pumping chamber 2 into which there open an upstream pipe 3 controlled by an inlet valve 4 , a downstream pipe 5 itself controlled by an outlet valve 6 .
- the pumping diaphragm 1 is intended to move between an extreme displacement position that reduces the volume of the pumping chamber 2 , leading to a raised pressure able to open the outlet valve 6 and an extreme return position that induces a reduced pressure able to close the outlet valve 6 and to open the inlet valve 4 .
- a drive mechanism 7 In order to expel the liquid from the pumping chamber 2 , a drive mechanism 7 , here symbolically depicted by a pushrod, pushes against the pumping diaphragm 1 in the direction of the inside of the pumping chamber.
- a drive mechanism 7 here symbolically depicted by a pushrod, pushes against the pumping diaphragm 1 in the direction of the inside of the pumping chamber.
- the intake phase of the pump it is the elasticity of the diaphragm which produces the return stroke generating, on the one hand, the intake and, on the other hand, returning the drive mechanism 7 to its starting position.
- suitable sizing of the diaphragm 1 is of key importance in order:
- the feature of foremost interest to us is the pressure reduction that the diaphragm is capable of supplying as a function of the displacement of its central core.
- Dimensioning the pumping diaphragm 1 first of all goes through the step of defining an operating range.
- the diaphragm In order to allow the diaphragm to pump right from the beginning of its stroke giving rise to a raised pressure, it is necessary for the diaphragm to be subjected to a preload, as will be seen later on.
- the preload of the diaphragm corresponds to a displacement by 0.4 mm from its rest position, the operating range extending from 0.4 mm to 1.2 mm.
- This operating zone is delimited by two vertical dotted lines in the diagram of FIG. 2 .
- the pressure in the pumping chamber must not drop below the vaporization pressure of water, represented by the lower line.
- the operating range needs to lie at a pressure below ⁇ 2 ⁇ 10 4 Pa, in order to counter the pressure of the liquid on the upstream side of the inlet valve 4 (1 ⁇ 10 4 Pa), the height of the water column to be taken in (5 ⁇ 10 3 Pa) and a minimum of 5 ⁇ 10 3 Pa in order to return the drive member 7 to its starting position.
- the working zone of the pumping diaphragm 1 is therefore defined by the rectangle bounded by the two vertical dotted lines and the two horizontal lines. Nonetheless, in order to take tolerances into consideration, a margin of 0.1 mm on the displacement of the pumping diaphragm is provided, as illustrated by the two continuous vertical lines. The possible operating zone then ranges between 0.3 and 1.3 mm, as illustrated in FIG. 2 .
- annular pumping diaphragm 1 has to have a rigidity such that the absolute pressure in the pumping chamber in the range of operation of the diaphragm situated between the extreme displacement position and the extreme return position lies within the following range:
- FIG. 2 again depicts the pressure-displacement curve for the aforementioned flat diaphragm. It may be noted that a situation is reached where the reduced pressure generated by the moving diaphragm x>0.7 mm is far too great, which could give rise to shockwaves (pressure waves in the upstream pipe 3 ), to boiling phenomena resulting from a drop in pressure and/or to cavitation. In other words, the gradient which is about ⁇ 1 ⁇ 10 4 Pa/0.1 mm is too steep.
- the challenge is to create a diaphragm which can work at the most constant pressure possible over the operating range. That would make it possible, firstly, to operate in the permissible operating zone (an essential condition) and secondly to soften the shockwaves in the upstream pipe 3 and avoid vaporization of the liquid or cavitation.
- a diaphragm of frustoconical shape has a pressure-displacement characteristic in the shape of a wave resulting from the buckling phenomenon.
- FIG. 4 illustrates the pressure-displacement curve of an annular diaphragm of the kind in FIG. 3 that forms the subject of the invention and the geometry of which is essentially characterized by a convex annular profile domed towards the outside of the pumping chamber.
- the outer edge of the diaphragm 1 is secured to an annular connecting element 1 b which has an annular groove 1 c intended to allow it to be attached to the wall of the pumping chamber 2 .
- the type of profile of pumping diaphragm 1 of FIG. 3 makes it possible to alter the distance between the plane of the central core 1 a of this diaphragm 1 and the plane that passes through the outer edge of the annular diaphragm 1 , where it is connected to the pumping chamber by the annular connecting element 1 b .
- the diameter of the central core 1 a can also be varied.
- various geometric parameters of the pumping diaphragm 1 it is possible to modify the amplitude of the pressure-displacement curve of FIG. 4 .
- the following effects are noted according to the characteristics of the diaphragm 1 of FIG. 3 :
- One way of reducing pressure sensitivity of the conical annular pumping diaphragm would be to reduce the operating range and to increase the preload, for example by switching from an operating range of 0.3 to 1.3 mm to an operating range of 0.7 to 1.2 mm. In such a case, it would be possible to reduce the rigidity of the diaphragm, the gradient of which would then typically be 1 ⁇ 10 4 Pa/0.2 mm and which would work over a narrower range, like that of FIG. 5 .
- FIGS. 6 and 7 indicate the pressure sensitivity of the diaphragm of FIG. 3 , as compared with a flat annular diaphragm with the same ratios of inside/outside diameters:
- the diagrams illustrate the central core 1 a of the diaphragm in two positions parallel to its plane with respect to its outer edge fixed to the pumping chamber.
- the diaphragm is illustrated in a first extreme position under preload of the central core 1 a , that corresponds to the extreme return position of the diaphragm, once under zero pressure and once under a pressure of ⁇ 3 ⁇ 10 4 Pa.
- the diaphragm is illustrated in its extreme displacement position corresponding to the end of the stroke used to expel liquid from the pumping chamber, once at zero pressure and once at 1.2 ⁇ 10 5 Pa.
- the diaphragm according to the present invention is not very sensitive to pressure. Specifically, very little difference can be observed between the curve in continuous line and the curve in dotted line in which it is subjected to a reduced pressure of ⁇ 3 ⁇ 10 4 Pa or even between the curves in chain line and the curve in dashes and crosses in which it is subjected to a pressure of 1.2 ⁇ 10 5 Pa.
- FIG. 7 a large effect that pressure has on the shape of the diaphragm can be seen under the same measurement conditions.
- FIG. 8 is a cross section through half of the diaphragm 1 from its centre to its periphery.
- the elastic modulus of which ranges between 0.1 MPa ⁇ E ⁇ 100 MPa. It is also the parameters b and e that can influence the pressure-displacement curve.
- ⁇ R/R ext leads to a reduction in the compression/relaxation of compression, a reduction in tension. This increase in ⁇ R/R ext also has the effect of reducing the pressure amplitude of the pressure-displacement curve (see FIG. 4 ), making it flatter.
- Increasing H/R ext has the effect of increasing the compression, relaxation of compression, of increasing the tension, of increasing the possible stroke of the diaphragm and of increasing the pressure amplitude of the pressure-displacement curve.
- the table below gives, by way of example, the dimensional and frequency/flow rate parameters of three pumping devices that form subjects of the present invention.
- the diaphragm is made of silicone. It could also be made of polyurethane or of EPDM.
- the pumping chamber is advantageously made of polycarbonate and the diaphragm of FIG. 3 is welded.
Abstract
This pump comprises a chamber and an annular pumping diaphragm secured to the said chamber and the inner edge of which is secured to a central drive part. This diaphragm has a convex domed profile so that its expulsion stroke results essentially in the energy-generating flexing of the intake stroke. The rigidity of the diaphragm is chosen so that the absolute pressure of the chamber lies within the following range:
P atm−(|ΔP valve
where: Patm=atmospheric pressure, Pvap=vapour pressure of the pumped fluid, ΔPvalve — in=pressure difference between the upstream and downstream side of the inlet valve for opening it, ΔPΔh — in=pressure difference in the upstream pipe between its distal end and the upstream side of the inlet valve as a result of the weight of the column of fluid, ΔPpd=pressure drop in the upstream pipe for the desired flow rate.
Description
- The present invention relates to a metering pump device for medical use comprising a pumping chamber, an annular pumping diaphragm the outer edge of which is secured to the said pumping chamber and the inner edge of which is secured to a central drive part that is more rigid than the said diaphragm, able to be displaced parallel to itself between an extreme return position and an extreme displacement position in its expulsion stroke and its intake stroke, respectively, these two positions lying one on each side of the plane containing the outer edge of the said annular diaphragm, the said pumping chamber comprising an inlet valve and an outlet valve which are respectively opened by a reduced pressure and by a raised pressure in the pumping chamber as a result of the movements of the said annular pumping diaphragm, the intake stroke of the said diaphragm resulting from the energy accumulated by the elastic deformation of the diaphragm during its expulsion stroke.
- Pumps of this type are already known. Production of such a pump as a metering pump for medical use, particularly as a single-use perfusion pump, presents numerous problems that known diaphragm pumps are unable to overcome.
- This pump needs to be accurate, and small while at the same time providing optimum flow rate, and needs to represent good value for money because it is not re-usable. The outlet valve of the pump has to provide safety against a free flow of liquid under a certain pressure, which is typically that of the column of liquid between a pouch of perfusion liquid and the pump, or the pressure resulting from accidental pressure applied to the pouch of liquid. Given this safety, the pumping diaphragm has to be able to withstand the working pressure, which is made up of a pressure to open the outlet valve that has to remain closed up to a pressure that is determined by safety standards, of a pressure drop in the downstream pipe and of a service pressure at the end of the downstream pipe.
- The pumping diaphragm has to be able to take in the liquid by moving from its extreme displacement position to its extreme return position creating enough of a reduced pressure in the presence of the pressure drop in the upstream and downstream pipes of the pumping device and of the pressure threshold of the inlet valve.
- This intake has to be achieved as quickly as possible in order to provide an optimum flow rate given the volume of the pumping chamber. However, in order to avoid shockwaves in the pipes, vaporization of the pumped liquid through a pressure drop greater than the vapour pressure of the liquid, and the effects of cavitation, the reduced pressure created by the return of the diaphragm must not be too great.
- Admittedly, the pumping diaphragm could be connected to the actuator for a two-way drive. However, such a solution would make the single use more complicated and therefore more difficult to manufacture and would make it more difficult to fit into the drive device. This method of driving also allows great precision in the control of the position of the diaphragm, and therefore great precision in the flow rate.
- Meeting all of these conditions, some of which oppose others, is therefore not straightforward.
- It is an object of the present invention to provide a solution which is able, at least in part, to meet the aforementioned conditions.
- To this end, the subject of the present invention is a metering pump device for medical use according to
Claim 1. - The various specifics and advantages of the invention will become better apparent from reading the following description of two embodiments of the metering pump device that forms the subject of the invention which are given by way of examples and illustrated schematically in the attached drawings.
-
FIG. 1 is a schematic general arrangement of the metering pump device; -
FIG. 2 is a diagram illustrating a typical operating pumping range using a flat pumping diaphragm; -
FIG. 3 is a cross section through a pumping diaphragm according to the invention intended to be connected to a pumping chamber; -
FIG. 4 is a pressure-displacement diagram for a pumping device using the diaphragm ofFIG. 3 ; -
FIG. 5 is a comparative pressure-displacement diagram of a pumping device using a flat diaphragm with the same dimensional ratios as the diaphragm ofFIG. 3 ; -
FIG. 6 is a diagram showing the pressure sensitivity of the diaphragm ofFIG. 3 ; -
FIG. 7 is a comparative pressure-sensitivity diagram for the flat diaphragm ofFIG. 5 ; -
FIG. 8 is a diagram of the diaphragm of the pumping device that forms the subject of the invention, showing the characteristic dimensions the dimensional ratios of which will be discussed further in the description. - The metering pump device that forms the subject of the invention is illustrated very schematically in
FIG. 1 , given that it is the elasticallydeformable pumping diaphragm 1, and the geometry and structure thereof, which constitute the innovative part of this invention. - Aside from the
pumping diaphragm 1, this device comprises apumping chamber 2 into which there open anupstream pipe 3 controlled by aninlet valve 4, adownstream pipe 5 itself controlled by anoutlet valve 6. Thepumping diaphragm 1 is intended to move between an extreme displacement position that reduces the volume of thepumping chamber 2, leading to a raised pressure able to open theoutlet valve 6 and an extreme return position that induces a reduced pressure able to close theoutlet valve 6 and to open theinlet valve 4. - It is a more particular object of the invention to determine how to produce a diaphragm that is able to meet a certain number of conditions.
- In order to expel the liquid from the
pumping chamber 2, adrive mechanism 7, here symbolically depicted by a pushrod, pushes against thepumping diaphragm 1 in the direction of the inside of the pumping chamber. During the intake phase of the pump, it is the elasticity of the diaphragm which produces the return stroke generating, on the one hand, the intake and, on the other hand, returning thedrive mechanism 7 to its starting position. As a result, suitable sizing of thediaphragm 1 is of key importance in order: - To have sufficient intake (be capable of creating enough of a reduced pressure) at the time of filling to combat any reduced pressure (pressure drop in a pipe, height of water column, valve with pressure threshold, etc.) and achieve sufficiently rapid filling of the pumping chamber, and to do so over the entire operating range thereof.
- However, in order to avoid shockwaves in the lines, effects of vaporization of the liquid contained in the
pumping chamber 1 as a result of a pressure drop beyond the vapour pressure of this liquid, or alternatively the effects of cavitation, the intake must not create too great a pressure drop. - Not to be too sensitive to the pressure in the upstream and downstream pipes, so as to maintain the precision of the incremental volumes pumped and therefore the precision of the flow rate, irrespective of the pressures upstream and downstream of the pumping device.
- We are now going to look at the sizing of the pumping diaphragm in order to obtain adequate filling.
- In what follows of the description, the behaviour of an annular diaphragm of flat profile surrounding a central core the thickness of which is chosen such that it deforms as little as possible, ideally not at all bearing in mind the stresses to which it is exposed, will be compared.
- The feature of foremost interest to us is the pressure reduction that the diaphragm is capable of supplying as a function of the displacement of its central core.
- Dimensioning the
pumping diaphragm 1 first of all goes through the step of defining an operating range. In order to allow the diaphragm to pump right from the beginning of its stroke giving rise to a raised pressure, it is necessary for the diaphragm to be subjected to a preload, as will be seen later on. - In the example adopted here, the preload of the diaphragm corresponds to a displacement by 0.4 mm from its rest position, the operating range extending from 0.4 mm to 1.2 mm. This operating zone is delimited by two vertical dotted lines in the diagram of
FIG. 2 . The pressure in the pumping chamber must not drop below the vaporization pressure of water, represented by the lower line. Finally, the operating range needs to lie at a pressure below −2×104 Pa, in order to counter the pressure of the liquid on the upstream side of the inlet valve 4 (1×104 Pa), the height of the water column to be taken in (5×103 Pa) and a minimum of 5×103 Pa in order to return thedrive member 7 to its starting position. The working zone of thepumping diaphragm 1 is therefore defined by the rectangle bounded by the two vertical dotted lines and the two horizontal lines. Nonetheless, in order to take tolerances into consideration, a margin of 0.1 mm on the displacement of the pumping diaphragm is provided, as illustrated by the two continuous vertical lines. The possible operating zone then ranges between 0.3 and 1.3 mm, as illustrated inFIG. 2 . - It is evident from that figure that the
annular pumping diaphragm 1 has to have a rigidity such that the absolute pressure in the pumping chamber in the range of operation of the diaphragm situated between the extreme displacement position and the extreme return position lies within the following range: -
P atm−(|ΔP valve— in |+|ΔP Δh— in |+|ΔP pd|)≧P>P vap - where:
-
- Patm=atmospheric pressure
- Pvap=vapour pressure of the pumped fluid
- ΔPvalve
— in=pressure difference between the upstream and downstream side of the inlet valve for opening it - ΔPΔh
— in=pressure difference in the upstream pipe between its distal end and the upstream side of the inlet valve as a result of the weight of the column of fluid - ΔPpd=pressure drop in the upstream pipe for the desired flow rate.
-
FIG. 2 again depicts the pressure-displacement curve for the aforementioned flat diaphragm. It may be noted that a situation is reached where the reduced pressure generated by the moving diaphragm x>0.7 mm is far too great, which could give rise to shockwaves (pressure waves in the upstream pipe 3), to boiling phenomena resulting from a drop in pressure and/or to cavitation. In other words, the gradient which is about −1×104 Pa/0.1 mm is too steep. Conversely, if attempts are made to reduce the gradient as far as possible, there is a risk of being at a pressure equal to −2×104 Pa at the prestress position of the diaphragm corresponding to a displacement of 0.3 mm and of not being able to complete the intake, or, put another way, of having an intake smaller than the pumping volume of the pump. - In order to address this problem, the challenge is to create a diaphragm which can work at the most constant pressure possible over the operating range. That would make it possible, firstly, to operate in the permissible operating zone (an essential condition) and secondly to soften the shockwaves in the
upstream pipe 3 and avoid vaporization of the liquid or cavitation. - In order to achieve a diaphragm something like this a diaphragm geometry that had a frustoconical profile in the state of rest was studied, this therefore resulting in the rigid central core of the flat diaphragm moving in a parallel plane, the annular part of the diaphragm then being conical in the state of rest. The forces resulting from the displacement of the rigid central core parallel to its plane in such a frustoconical diaphragm can be broken down into tension-compression forces and to forces of bending of the flexible annular part.
- A distinction is made between three types of behaviour as the central core gradually moves parallel to its plane:
-
- The diaphragm works chiefly in compression, bending being of secondary importance.
- Compression decreases with the displacement of the core as far as a threshold where the diaphragm buckles and compression forces are relaxed. Bending forces increase.
- The compression forces are completely relaxed and the diaphragm works in tension. The bending forces continue to increase with displacement.
- Hence, a diaphragm of frustoconical shape has a pressure-displacement characteristic in the shape of a wave resulting from the buckling phenomenon.
- A distinction can be drawn between two different types of behaviour according to the thickness of such a diaphragm:
-
- When the thickness is very small and the cone angle is pronounced, the diaphragm undergoes a great deal of buckling, and behaves like a bi-stable diaphragm, the pressure-displacement characteristic of which forms a very pronounced S shape. In this case, it is the tension-compression forces which dominate.
- If the thickness is great and the gradient small, the buckling phenomenon appears little if at all; this then is a stable diaphragm, the pressure-displacement characteristic of which does not form an S shape. It is the bending forces that dominate.
- A combination of these two extreme solutions, like the one illustrated in
FIG. 3 , gives an interesting curve.FIG. 4 illustrates the pressure-displacement curve of an annular diaphragm of the kind inFIG. 3 that forms the subject of the invention and the geometry of which is essentially characterized by a convex annular profile domed towards the outside of the pumping chamber. In this embodiment, the outer edge of thediaphragm 1 is secured to an annular connecting element 1 b which has an annular groove 1 c intended to allow it to be attached to the wall of thepumping chamber 2. - The type of profile of pumping
diaphragm 1 ofFIG. 3 makes it possible to alter the distance between the plane of the central core 1 a of thisdiaphragm 1 and the plane that passes through the outer edge of theannular diaphragm 1, where it is connected to the pumping chamber by the annular connecting element 1 b. The diameter of the central core 1 a can also be varied. Thus, by varying various geometric parameters of the pumpingdiaphragm 1, it is possible to modify the amplitude of the pressure-displacement curve ofFIG. 4 . The following effects are noted according to the characteristics of thediaphragm 1 ofFIG. 3 : -
- The more acute the cone angle, the more the tension-compression forces dominate and the more the pressure-displacement characteristic of the diaphragm adopts a pronounced S shape.
- The thicker the
annular diaphragm 1, the more the bending forces dominate: - the less the pressure-displacement characteristic adopts a pronounced S shape
- the steeper the gradient of the pressure-displacement characteristic
- the narrower the operating range of the diaphragm
- The more domed the shape of the
annular diaphragm 1, the more the bending forces dominate and the lesser the extent to which the pressure-displacement characteristic adopts a pronounced S shape.
- One way of reducing pressure sensitivity of the conical annular pumping diaphragm would be to reduce the operating range and to increase the preload, for example by switching from an operating range of 0.3 to 1.3 mm to an operating range of 0.7 to 1.2 mm. In such a case, it would be possible to reduce the rigidity of the diaphragm, the gradient of which would then typically be 1×104 Pa/0.2 mm and which would work over a narrower range, like that of
FIG. 5 . - Nevertheless, a diaphragm such as this would have the following disadvantages:
-
- The preload of the diaphragm is increased, which means that the forces within the diaphragm are greater.
- The flow rate of the pumping device is reduced in the same ratio as the operating range.
- A device such as this is far more sensitive to pressure because the thickness of the diaphragm has been reduced in order to reduce the gradient of the pressure-displacement curve which means that the pressure sensitivity of such a diaphragm is greatly increased, this significantly reducing the precision of the flow rate.
- In order to illustrate this sensitivity to pressure,
FIGS. 6 and 7 indicate the pressure sensitivity of the diaphragm ofFIG. 3 , as compared with a flat annular diaphragm with the same ratios of inside/outside diameters: - In each case, the diagrams illustrate the central core 1 a of the diaphragm in two positions parallel to its plane with respect to its outer edge fixed to the pumping chamber.
- The diaphragm is illustrated in a first extreme position under preload of the central core 1 a, that corresponds to the extreme return position of the diaphragm, once under zero pressure and once under a pressure of −3×104 Pa.
- The diaphragm is illustrated in its extreme displacement position corresponding to the end of the stroke used to expel liquid from the pumping chamber, once at zero pressure and once at 1.2×105 Pa.
- It may be seen in
FIG. 6 that the diaphragm according to the present invention is not very sensitive to pressure. Specifically, very little difference can be observed between the curve in continuous line and the curve in dotted line in which it is subjected to a reduced pressure of −3×104 Pa or even between the curves in chain line and the curve in dashes and crosses in which it is subjected to a pressure of 1.2×105 Pa. By contrast, inFIG. 7 , a large effect that pressure has on the shape of the diaphragm can be seen under the same measurement conditions. - The various preferred dimensional parameters for the diaphragm in order to obtain the desired effects as far as the pressure-displacement characteristic is concerned, and as far as the reduction in pressure sensitivity is concerned are indicated in
FIG. 8 which is a cross section through half of thediaphragm 1 from its centre to its periphery. - The dimensional parameters of this diaphragm that contribute to obtaining the aforementioned characteristics are as follows, and need to fall within the following ranges:
-
- for an elastic material the elastic modulus of which ranges between 0.1 MPa≦E≦100 MPa. It is also the parameters b and e that can influence the pressure-displacement curve.
- Increasing ΔR/Rext leads to a reduction in the compression/relaxation of compression, a reduction in tension. This increase in ΔR/Rext also has the effect of reducing the pressure amplitude of the pressure-displacement curve (see
FIG. 4 ), making it flatter. - Increasing H/Rext has the effect of increasing the compression, relaxation of compression, of increasing the tension, of increasing the possible stroke of the diaphragm and of increasing the pressure amplitude of the pressure-displacement curve.
- Increasing e/ΔR increases the bending effects and the rigidity and reduces the amplitude of the pressure-displacement curve (
FIG. 4 ), flattening it. - The table below gives, by way of example, the dimensional and frequency/flow rate parameters of three pumping devices that form subjects of the present invention.
-
Volume [μl] 75 10 1 Ediaphragm [MPa] 3.5 3.5 3.5 Rext [mm] 6.0 2.5 1.0 Rcentral [mm] 3.5 1.5 0.6 H [mm] 0.5 0.4 0.3 Stroke [mm] 1 0.8 0.5 Freqmin [Hz] 0.004 0.003 0.003 Freqmax [Hz] 4 15 30 Flow ratemin [ml/h] 1 0.1 0.01 Flow ratemax [ml/h] 1000 500 100 - Advantageously, the diaphragm is made of silicone. It could also be made of polyurethane or of EPDM. The pumping chamber is advantageously made of polycarbonate and the diaphragm of
FIG. 3 is welded.
Claims (9)
1. Metering pump device for medical use comprising a pumping chamber, an annular pumping diaphragm the outer edge of which is secured to the said pumping chamber and the inner edge of which is secured to a central drive part that is more rigid than the said diaphragm, able to be displaced parallel to itself between an extreme return position and an extreme displacement position in its expulsion stroke and its intake stroke, respectively, these two positions lying one on each side of the plane containing the outer edge of the said annular diaphragm, the said pumping chamber comprising an inlet valve and an outlet valve which are respectively opened by a reduced pressure and by a raised pressure in the pumping chamber as a result of the movements of the said annular pumping diaphragm, the intake stroke of the said diaphragm resulting from the energy accumulated by the elastic deformation of the diaphragm during its expulsion stroke, characterized in that the said annular pumping diaphragm has, in the said extreme return position, a convex annular profile domed towards the outside of the said pumping chamber so that its expulsion stroke results essentially in the energy-generating flexural deformation of the intake stroke and in the annular compression/relaxation of compression of the said convex annular profile upon each outward stroke of the said diaphragm, the rigidity of the diaphragm being chosen so that the absolute pressure in the pumping chamber in the range of operation of the diaphragm situated between the extreme displacement position and the extreme return position lies within the following range:
P atm−(|ΔP valve— in |+|ΔP Δh — in |+|ΔP pd|)≧P>P vap
P atm−(|ΔP valve
where:
Patm=atmospheric pressure
Pvap=vapour pressure of the pumped fluid
ΔPvalve — in=pressure difference between the upstream and downstream side of the inlet valve for opening it
ΔPΔh — in=pressure difference in the upstream pipe between its distal end and the upstream side of the inlet valve as a result of the weight of the column of fluid
ΔPpd=pressure drop in the upstream pipe for the desired flow rate.
2. Pumping device according to claim 1 , in which the said diaphragm is made of silicone.
3. Device according to claim 1 , in which the ratio between the radial width ΔR of the annular part of the pumping diaphragm and the exterior radius thereof lies within the range:
4. Device according to claim 1 , in which the ratio between the radial width ΔR of the annular part of the annular pumping diaphragm and the length of the stroke of the diaphragm between its extreme return position and its extreme displacement position lies within the range:
5. Device according to claim 1 , in which the ratio between the thickness e of the annular pumping diaphragm and the radial width ΔR of the annular part thereof lies within the range:
6. Device according to claim 1 , in which the ratio between the maximum distance between the chord subtended by the concave side of the annular part of the diaphragm and the thickness e of this diaphragm lies within the range:
for an elastic material the elastic modulus E of which ranges between 0.1 MPa≦E≦100 MPa.
7. Device according to claim 1 , in which said range of operation lies between 0.7 and 1.2 mm, with a rigidity of the diaphragm having a gradient of typically 1.104 Pa/0.2 mm.
8. Device according to claim 1 , in which the pumping chamber is made of polycarbonate.
9. Device according to claim 1 , in which the annular pumping diaphragm is an element overmoulded on the pumping chamber.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CH1982/09 | 2009-12-23 | ||
CH01982/09A CH702436A1 (en) | 2009-12-23 | 2009-12-23 | DOSING PUMP FOR MEDICAL USE. |
PCT/CH2010/000319 WO2011094878A1 (en) | 2009-12-23 | 2010-12-20 | Diaphragm metering pump for medical use |
Publications (1)
Publication Number | Publication Date |
---|---|
US20120308412A1 true US20120308412A1 (en) | 2012-12-06 |
Family
ID=43971530
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/518,376 Abandoned US20120308412A1 (en) | 2009-12-23 | 2010-12-20 | Diaphragm Metering Pump Device for Medical Use |
Country Status (4)
Country | Link |
---|---|
US (1) | US20120308412A1 (en) |
EP (1) | EP2515971B1 (en) |
CH (1) | CH702436A1 (en) |
WO (1) | WO2011094878A1 (en) |
Cited By (10)
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US8721883B2 (en) | 2002-06-04 | 2014-05-13 | Fresenius Medical Care Deutschland Gmbh | Medical fluid cassettes and related systems |
US8932032B2 (en) | 2005-07-13 | 2015-01-13 | Fresenius Medical Care Holdings, Inc. | Diaphragm pump and pumping systems |
US8986254B2 (en) | 2009-03-20 | 2015-03-24 | Fresenius Medical Care Holdings, Inc. | Medical fluid pump systems and related components and methods |
US9011114B2 (en) | 2011-03-09 | 2015-04-21 | Fresenius Medical Care Holdings, Inc. | Medical fluid delivery sets and related systems and methods |
US9180240B2 (en) | 2011-04-21 | 2015-11-10 | Fresenius Medical Care Holdings, Inc. | Medical fluid pumping systems and related devices and methods |
US9421314B2 (en) | 2009-07-15 | 2016-08-23 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassettes and related systems and methods |
US9500188B2 (en) | 2012-06-11 | 2016-11-22 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassettes and related systems and methods |
US9561323B2 (en) | 2013-03-14 | 2017-02-07 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassette leak detection methods and devices |
US9610392B2 (en) | 2012-06-08 | 2017-04-04 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassettes and related systems and methods |
US10117985B2 (en) | 2013-08-21 | 2018-11-06 | Fresenius Medical Care Holdings, Inc. | Determining a volume of medical fluid pumped into or out of a medical fluid cassette |
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Cited By (26)
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US9101709B2 (en) | 2002-06-04 | 2015-08-11 | Fresenius Medical Care Deutschland Gmbh | Dialysis fluid cassettes and related systems and methods |
US8926835B2 (en) | 2002-06-04 | 2015-01-06 | Fresenius Medical Care Deustschland Gmbh | Dialysis systems and related methods |
US9827359B2 (en) | 2002-06-04 | 2017-11-28 | Fresenius Medical Care Deutschland Gmbh | Dialysis systems and related methods |
US10471194B2 (en) | 2002-06-04 | 2019-11-12 | Fresenius Medical Care Deutschland Gmbh | Dialysis systems and related methods |
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US11384748B2 (en) | 2005-07-13 | 2022-07-12 | Baxter International Inc. | Blood treatment system having pulsatile blood intake |
US10590924B2 (en) | 2005-07-13 | 2020-03-17 | Baxter International Inc. | Medical fluid pumping system including pump and machine chassis mounting regime |
US8932032B2 (en) | 2005-07-13 | 2015-01-13 | Fresenius Medical Care Holdings, Inc. | Diaphragm pump and pumping systems |
US10578098B2 (en) | 2005-07-13 | 2020-03-03 | Baxter International Inc. | Medical fluid delivery device actuated via motive fluid |
US8986254B2 (en) | 2009-03-20 | 2015-03-24 | Fresenius Medical Care Holdings, Inc. | Medical fluid pump systems and related components and methods |
US9421314B2 (en) | 2009-07-15 | 2016-08-23 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassettes and related systems and methods |
US10507276B2 (en) | 2009-07-15 | 2019-12-17 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassettes and related systems and methods |
US9011114B2 (en) | 2011-03-09 | 2015-04-21 | Fresenius Medical Care Holdings, Inc. | Medical fluid delivery sets and related systems and methods |
US9624915B2 (en) | 2011-03-09 | 2017-04-18 | Fresenius Medical Care Holdings, Inc. | Medical fluid delivery sets and related systems and methods |
US9180240B2 (en) | 2011-04-21 | 2015-11-10 | Fresenius Medical Care Holdings, Inc. | Medical fluid pumping systems and related devices and methods |
US10143791B2 (en) | 2011-04-21 | 2018-12-04 | Fresenius Medical Care Holdings, Inc. | Medical fluid pumping systems and related devices and methods |
US10463777B2 (en) | 2012-06-08 | 2019-11-05 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassettes and related systems and methods |
US9610392B2 (en) | 2012-06-08 | 2017-04-04 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassettes and related systems and methods |
US11478578B2 (en) | 2012-06-08 | 2022-10-25 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassettes and related systems and methods |
US9500188B2 (en) | 2012-06-11 | 2016-11-22 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassettes and related systems and methods |
US10539481B2 (en) | 2013-03-14 | 2020-01-21 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassette leak detection methods and devices |
US9561323B2 (en) | 2013-03-14 | 2017-02-07 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassette leak detection methods and devices |
US11262270B2 (en) | 2013-03-14 | 2022-03-01 | Fresenius Medical Care Holdings, Inc. | Medical fluid cassette leak detection methods and devices |
US10117985B2 (en) | 2013-08-21 | 2018-11-06 | Fresenius Medical Care Holdings, Inc. | Determining a volume of medical fluid pumped into or out of a medical fluid cassette |
US11291753B2 (en) | 2013-08-21 | 2022-04-05 | Fresenius Medical Care Holdings, Inc. | Determining a volume of medical fluid pumped into or out of a medical fluid cassette |
Also Published As
Publication number | Publication date |
---|---|
WO2011094878A1 (en) | 2011-08-11 |
CH702436A1 (en) | 2011-06-30 |
EP2515971A1 (en) | 2012-10-31 |
EP2515971C0 (en) | 2023-08-09 |
EP2515971B1 (en) | 2023-08-09 |
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Legal Events
Date | Code | Title | Description |
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |