Patent Application
20080232986
The present invention relates to a tubular pump which has outstanding features of novelty and inventive step.
In liquid metering technology, for example in pharmaceutical or other fields, it is necessary to use pumps which can meter various types of liquid, gel or the like with great precision, while achieving excellent asepsis and operational reliability. Furthermore, the quantities to be metered in each cycle must be able to be easily varied.
Different types of mechanical pumps are known at present, for example piston pumps in which liquid is metered by the positive movement of a piston, combined with a valve system for supplying and discharging liquid and with different means for varying the quantities metered in each cycle. Also known are systems in which other types of pump are used together with inlet and outlet control valves, including in some cases storage receivers situated before the metering conduits.
Said types of pump known at present have a number of drawbacks which hinder their use and make their practical application more expensive. Firstly, account must be taken of the difficulty in cleaning the pump and the valves thereof when changing the liquid to be metered, this being an awkward and relatively unsafe task from the point of view of asepsis. There are also problems of reliability, as the pumps are basically mechanical pumps, thus implying a large number of parts which could suffer damage, wear, etc. Among the drawbacks of pumps which are known at present, account must also be taken of the inevitable contact between the liquid and various materials, in many cases metal materials, which is also disadvantageous for some types of liquid to be metered.
Another type of known pump is the peristaltic pump in which a compression element thoroughly compresses a tubular element which is full of liquid to be pumped, moving along a variable portion of the tube, thereby causing the positive displacement of the contents of the tube and the pumping action. However, a major disadvantage of these pumps is the complete mechanical collapse of the tube, which accelerates the ageing thereof and detrimentally affects the integrity of the metered product, since in many cases some molecules of the product can suffer damage due to compression. Further disadvantages of peristaltic pumps are the unsatisfactory dose repeatability and the high dependency of the metered quantity on the precise path of the roller or rollers, since in many cases the final positions are not entirely precise, thereby affecting the repeatability of the dose.
Taking into account the prior art, the inventor has carried out a plurality of tests and investigations to produce a pump which overcomes, at least substantially, the earlier drawbacks. The inventor's research and tests have resulted in the production of a tubular-type pump which has original features and which provides superior quality in terms of asepsis, constructional simplicity and reliability.
Basically, the new tubular pump is based on the use of a tubular element made of resilient material, such as for example rubber, PVC, silicone, etc., for containing liquid which is to be metered and which travels in an intermittent and controlled manner through the tube as a result of an action of transverse compression thereof, which is converted into a pumping of liquid contained in the tube by combination of said action of transverse compression with a liquid inlet valve which will be closed during compression and a liquid outlet valve towards the receiver to be filled which will open during compression. When the action of compression transverse of the tube is complete and natural recovery thereof has been made possible by its own resilience, the inlet valve will be open to allow the new liquid to enter and the outlet valve will be closed to prevent the unchecked discharge of liquid towards the receivers to be filled. The action of compression preferably takes place between a lower surface or planar die and an upper planar ramming member, in such a way that, for a given tube, the quantity of liquid will vary with the compression stroke and the length thereof, since, once compressed, it will represent the decrease in volume of the tube from its original shape with a circular cross-section to the final shape in which it will adopt the shape of a rectangle with plane parallel sides and ends in the shape of semi-circumferences with diameters equal in size to the smaller side of the rectangle. Given the resilience of the tube, recovery of the original shape after each compression cycle, i.e. metering, is ensured.
The precise section of the tube can also be varied by the drawing thereof, which will be a means for varying the quantity of liquid provided in each compression cycle of the ramming member.
The pump will be able to comprise a plurality of tubular elements for the simultaneous metering of various lines with an identical or different product, and with likewise variable doses, making it possible to fill different receiver lines or supply different liquids to the same receivers of a given container line. The new pump can therefore be used in a very versatile manner.
The tube can be made of a single part from the initial receiver to the final destination; and this makes cleaning the pump very easy and safe.
Excessive stroke values are not required for the pump to operate properly. On the contrary, one significant feature to take into account is specifically that the transverse compression level of each tubular element in the pump will be very moderate and, once the tube is distorted to a limited extent, this allows for extraordinarily long-term operation of each tube while maintaining the operational features thereof.
One of the applications of the pump according to the present invention is filling the receivers with cards for clinical analysis in which the micro-receivers of each card will be able to receive the different products in a liquid or gel state in order to fulfil their function.
One example of a pump according to the present invention will comprise three successive units which have a similar structure and which are synchronised in their operation, one of them having, for metering, a planar base for receiving the flexible and resilient tubular element and a compression ramming member, likewise planar, actuated by any appropriate means, for example hydraulic, pneumatic, electromagnetic means, etc., in order to compress the tubular element, its downward stroke being well-controlled, preferably by fixed stops, in such a way that compression of the tubular element will be very precise and smooth. An initial unit and a final unit of the three-unit assembly of the pump will be for completely closing the tubular element, which operates as a uniflow valve, and the intermediate unit will be for carrying out the compression for the metering of the product. Fixing the tube or tubes corresponding to the compression unit will allow possible drawing of the tubes, in order to adjust the metering of each individual action of compression. In order to allow a decrease or increase, the metering tubes can have an initial drawing which can be increased or decreased.
As will be appreciated, the product inlet and outlet valve units can be produced by any technically appropriate means, production thereof preferably being by means of a base assembly for receiving the tubular supply and discharge element and a ramming member to compress the tube until it closes. As is obvious, the tubular elements of the valve units may differ from the tubular metering elements, having appropriate flexibility and being easily changeable. Furthermore, the structure of the base and compression ramming member for closing the tubes by joint action between the two may vary substantially since, although the base and ramming member may be planar, a curved base and/or pointed or otherwise shaped ramming member can also be used, providing that enough compression can be exerted on the tubular element for complete throttling thereof, thereby closing it.
Operation of the pump will be cyclical, actuating in a successive manner, after the initial filling of the tube, the inlet closure valve, the metering element for partial compression of the metering tubes and the outlet valve which will allow the pumped quantities to be metered. An electronic assembly will control the metering pump as well as reversing the direction of passage of the products to be metered. To simplify assembly, should the conditions necessary for the product allow it (in terms of metered volume, desired accuracy, product features), non-return valve assemblies can be used, advantageously eliminating the need for synchronisation.
For a better understanding, an embodiment of the present invention is illustrated, by way of an explanatory but not limiting example, in the accompanying drawings in which:
Referring to
By way of example, an embodiment is shown in the figures, which implements the pump according to the present invention. As can be seen in the figures, the pump comprises a central unit 6 for metering and individual units 7 and 8 for controlling the entry and exit of the product to be metered. The metering unit 6 has one or more resilient tubes, only one of which is represented by the numeral 9, arranged over a preferably planar base 10 and a ramming member 11 which is actuated by the head of the unit 6 by hydraulic, pneumatic, electromagnetic or other means. The tubular element or elements 9 will only be compressed in part, i.e. for the deformation of the tubular element but without producing contact between the internal walls thereof, a further feature being that said action of compression has features of great smoothness, which will duly control the speed of the ramming member. On the other hand, the stroke will be adjustable depending on the quantity to be metered in each cycle, being fixed between cycles by means of mechanical stops or by electronically controlling the position of the ramming member by means of sensors which control movement of the motor using pulses (encoders).
The tubes 9 will be fixed to the base 10 by means of head pieces such as 12 and 13, one of them being fixed and the other displaceable for varying the length of the tubular element 9, thereby adjusting the quantity to meter both by varying the internal diameter of the opening of the tubular element 9 and by varying the external diameter thereof.
The base 10 receiving the tubular elements 9 will preferably be planar for greater simplicity, but it is obvious that its shape can be varied providing that the lower supporting functions of the tube on the base 10 and individual compression of each tube are carried out. As is obvious, simultaneous arrangement on the base 10 of tiered forms of the base or even of the compression member 11 for adapting to different metering processes or diameters of the tubes can also be envisaged when, as is common, there are a plurality of metering tubes.
Although not shown in the figures, optionally adjustable fixed mechanical stops adjacent to the base 10 can determine the end of stroke of the ramming member 11. Possible arrangements for controlling the position by electronic means which can control the movement of the head piece driving motor by number of pulses (encoding system) are also illustrated.
Units 7 and 8 have the function of cyclically closing the tubular elements for the supply and discharge of the product to be metered. The figures show a structure similar to the drive unit for metering 6, i.e. with respective bases 14 and 15 and respective ramming members 16 and 17. However, it is obvious that said units which act as valves can be formed by other means for compressing the tube, for example, by means of a punch system to compress the tube and die provided with a shape for receiving the tube or other valve systems, including types different to that of compression of tubular elements which have been shown.
Although the element which conveys the product to be metered has been shown in a tubular form on the whole path of the inlet and outlet units as well as the compression unit, it will be appreciated that said elements can be produced in other types of conduits which are flexible or otherwise, with the exception of the regions in which they are controlled by compression, whether it be in the valve units or in the compression unit.
Equally, although one tubular compression element 9 is shown, the pump can comprise a plurality of tubes to simultaneously meter a plurality of micro-receivers, for example, eight, which is the number of micro-receivers which are usually arranged in each card for clinical analysis.
In the pump according to the present invention, particular care shall be taken that the mechanical forces on the tubular elements, in the case of both the compression unit and the valve units if flexible tubular elements are used, are smooth or do not harm the physical integrity of the tubular elements, do not reduce the useful life thereof nor harm the integrity of the molecules of the product to be metered. Thus, for example, in the tube nipping units which perform the function of valves, deformation of the tube will be controlled so that complete closure thereof is guaranteed, while limiting the deformation of the material of the tube so that it does not undergo permanent damage. For example, one form of adjustment will be that the separation between the external walls of the tubular element, after compression, is less than twice the thickness of the tube and that said separation is not smaller than a given value in order to limit the transverse deformation of the tube, for example, the thickness of the tube itself.
In one specific design, the tubes of the metering part will have the greatest dimensional accuracy possible, as well as features of shape memory, resilience and flexibility, since the adjustment of the metering will take place via longitudinal drawing of the tube. These tubes will each have, in one specific embodiment, end rings which will allow them to be anchored to the fixed and moving anchors which are indicated. The speed at which the product contained in the tubular element is discharged can be adjusted by regulating the speed of the compression ramming member. The frequency of the metering can also be adjusted to the desired value.
The assembly of controls, sensors and adjustments of the pump are incorporated in an electronic assembly thereof, which is not illustrated.
The present invention is described by way of example on the basis of the embodiment shown, which does not have to be considered as limiting. On the contrary, all the variations which can be introduced into the pump according to the present invention by experts in the art with knowledge of the present invention will have to be considered included in the field thereof if they do not exceed the scope of the accompanying claims. Application of the pump according to the present invention can also be variable, extending to applications other than filling analysis cards.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200700745 | Mar 2007 | ES | national |
