FR2520252A1 - Magnetic mixer for nutrient fluids for pump fed patient - allows no contact between rotating element and mixing vessel - Google Patents

Abstract

Mixer comprises a vessel in which a magnetic element is rotated about a vertical axis by a magnetic field with its source, partic. an electric motor, outside the vessel. The magnetic element is suspended at the bottom of a rotary, vertical rod or thread which has its upper end attached to a fixed support. The length of the rod or thread holds the rotating element clear of the base of the vessel, through which the magnetic field exerts a driving torque on the element. The magnetic element can be a bar magnet, a soft iron rod or a rod of stainless steel. The length of suspension rod or thread between fixed support and magnetic element is pref. adjustable. Pref. a mixing rotor is fixed to the suspension rod or thread above the magnetic element. The magnetic element is no longer subjected to wear by friction with the base of the vessel. The life of the element is extended indefinitely. There is no danger of particles of the element, e.g. P.T.F.E. coating, being rubbed off and mixed with the invalid's feed.

Description

 The present invention relates to an improved stirring system. It relates more particularly to a stirring device useful for stirring liquids, or mixtures of liquids and solid particles in suspension, in particular in nutrition pumps.

 Although the stirring system according to the invention can be applied more generally to any apparatus whose operation implements or requires mixing of a fluid medium, or homogenization of liquid mixtures or mixtures of liquids and particles solids in suspension, it will be described below, for simplicity, with reference to the particular case of a stirring device for a nutrition pump. All that is said for this particular, non-limiting application, however applies mutatis mutandis to other apparatus or the stirring can be done the same along a vertical axis of rotation of the stirring device.

 Machines called "nutrition pumps" are widely used and used to artificially feed patients who are unable to feed themselves. Since it is essential for this type of artificial nutrition that the fluidized foods are permanently perfectly homogeneous, and taking into account that their components are not soluble in the fluidization medium, it has hitherto been practiced common to use stirring devices composed either of pallets actuated by an electric motor, or more commonly of magnetic bars actuated by an electric motor acting by attraction on the magnet of the bar, which turned on the bottom of the container where s' operates the mixing.

 These bars, usually made of Teflon (trade name of a polytetrafluoroethylene) had the disadvantage of wearing out quickly, soaking up fine particles of Teflon which, passing through food, frequently resulted in clogging the administration probe; on the other hand, the patient ingested Teflon with his food.

Furthermore, the magnetic bars had to be replaced frequently and in practice they were even often lost by the users of these nutrition pumps.

 The object of the present invention is to remedy these drawbacks and to provide a more suitable stirring system, in particular - but not exclusively - useful in a nutrition pump. These objectives, as well as others which will emerge from the following description, are achieved, thanks to a suspended magnetic stirring system.

 The first object of the invention is a large stirring device, a magnetic stirring member driven by a rotational movement under the effect of a rotary motor magnet system, in particular an electric motor, characterized in that the magnetic stirring member is made integral with the lower end of a wire or a rod which is vertical in the position of use and the other end of which is fixed to a fixed attachment point, so as to ability to maintain freedom of rotation along an axis passing through senledit, wire or rod only through this point, / having a length such that the magnetic stirring member rotates a short distance from the bottom of the container where it operates and practically without contact with this bottom, through which the magnetic force of rotation is exerted.

 By "magnetic stirring member" is meant both a literal magnet (preferably a magnetic bar) and a soft iron element. In the type of application more particularly described here, the soft iron element is advantageously a rod made of stainless steel, for example a rod made of stainless steel containing about 17% chromium or of hardened 18/8 stainless steel.

 Such a system represents in all cases a synchronous magnetic transmission system, using a like leader.

 Regardless of this, a wire or a rod can be chosen as the suspension element.

 In the application of nutrition pumps, the wire which the skilled person is required to retain, if necessary near routine tests, must not become impregnated in contact with fluidized food and must be able to be sterilized.

 A relatively rigid wire is preferred, advantageously of nylon type polyamide or a rod, such as preferably a rod of stainless steel.

 The connection between the wire or the rod and the magnetic stirring member and that between the wire or the rod and the fixed attachment point can be made by any suitable means. For example, the wire or the rod can be fixed, in the position of use, with the interposition of a pin, to a high attachment member, such as a hook which is itself connected to the fixed attachment point.

 As a variant, the upper end, in service1 of the wire or of the rod can be retained by a sleeve supported on a ring or a ball bearing device made integral with the above-mentioned fixed point.

 The fixed attachment point is located on the substantially central, lower part of the lid of the container where the agitation is to take place or of any other element which covers this container more or less completely. In practice, in the case of the Nnutrition pump, this fixed attachment point is at the center of one of the faces of the lid of the container where the mixing takes place or of the lid of the pump if it is of a model that includes such a container in its structure.

 The device according to the invention may also include means for adjusting the distance between the attachment point and the magnetic stirring member, preferably located in the part of the wire or rod close to its attachment point or even that merges with its hooking member.

 For applications such as those of the nutrition pump, the attachment system, possibly including this adjustment means, should be simple to be easily sterilizable before use.

 In such a system, which represents only a derisory cost compared to the traditional system, the magnetic bar does not wear out and does not risk being lost.

 As a variant, this device can advantageously also include at least one other stirring member, fixed between the two ends of the above-mentioned wire or rod and set in motion by the rotation of the wire or rod; this rotation is maintained by the rotation of the magnetic stirring member. This other stirring member can be any, but it is preferably composed of blades, the shape and the inclinations of which can be chosen at will by a person skilled in the art.

 This intermediate induced stirring can be located for example at mid-height of the above-mentioned wire or rod; or at one or more other points along this thread this point to a level where rod; advantageously, it is placed at a height such that it operates in the reci / the local agitation surplus thus provided can counterbalance risks of non-uniformity, due to certain components of lower density than the others present in the mixture homogenize or to thin.

 The invention also relates to a nutrition pump comprising a magnetic stirring member which can be rotated in the container in which the foodstuffs to be fluidized and homogenized are placed, characterized in that it comprises a stirring device as described above in its various variants.

 The invention is described below more specifically with reference to the single figure of the accompanying drawing board, which represents in partial schematic section the upper part of a nutrition pump provided with a stirring device in accordance with one of the variants of the invention and corresponding to an exemplary embodiment thereof.

 This example is purely illustrative and does not limit the present invention in any way.

 As can be seen in the appended figure, the upper body of the pump comprises a housing 1 in which a container 2 takes place, where the agitation of the fluidized food is to take place. The housing 1 of the upper pump body and the container 2 are concealed by a cover 3. A magnetic bar 4 is fixed to a nylon thread 5, the other end of which is fixed to a hook 6, with the interposition of a pin 7 ; the hook 7 is inserted into a hooking point provided for this purpose practically in the center of the cover 3.

 Noticeably at the mid-length of this wire is attached a stirrer with 4 plastic blades 8.

 When the assembly of the stirring device thus formed is placed in such a way that the wire assumes the function of a vertical axis of rotation, and the free space between the magnetic bar and the bottom of the container is only about 1 mm, the synchronous rotation under the action of a driving magnet (not shown) acting just below the bottom of the container 2 puts all the stirring devices in rotation (with the exception of the organ top hooking over the pin) and ensures proper mixing and homogenization of the fluidized foods introduced into the container, without significant wear of the magnetic bar and therefore also without risk of blockage of the probe through which the fluidized foods are administered.

Claims (7)

 1. Stirring device comprising a  magnetic gitation (4) animated by a rotational movement under  the effect of a motorized rotary magnet system, in particular a  electric motor, characterized in that the agitated member  magnetic tion (4) is secured to the lower end  ri-eure of a wire or a rod (5) which is vertical in posi  tion of use and the other end of which is fixed to a  fixed attachment point, so that a  freedom of rotation along an axis passing substantially through this  point, said wire or rod having a length such that the  magnetic stirring wheel turns at a short distance from the  bottom of container Od it operates and practically without contact  with this background, through which the magnetic force is exerted  of rotation.  2. Device according to claim 1, character  laughed at in that the magnetic stirrer is a bar  magnetized water or a soft iron element.  3. Device according to claim 1 character  laughed at in that the magnetic stirrer is a rod  Stainless steel.  4. Device according to any one of the claims  cations 1 to 3, characterized in that the top attachment is  made on the substantially central, lower part of a  element coming to cover the story more or less completely  where the agitation takes place.  5. Device according to any one of the claims 1 to 4, characterized in that it comprises a means of  adjustment of the distance between the attachment point and ltor-  gane of magnetic stirring.  6. Device according to any one of the claims  cations 1 to 5, characterized in that it comprises at least one  another agitating member, fixed between the two ends of the  wire or rod and set in motion by the rotation of the wire  or stem.  7. Nutrition pump, comprising an actuator  Magnetic tation which can be rotated in the re  container in which the food to be thinned and  homogenize, characterized in that it comprises a disposi  stirring tif according to any one of claims 1  to 6.