FR2503799A1 - PERISTALTIC PUMP FOR MEDICAL APPLICATIONS - Google Patents

Abstract

THIS PUMP INCLUDES A TUBE 1, ROUTED BY THE PUMP FLUID, ON A LONGITUDINAL TRUNCON 8 WHICH CAN ACT ROLLERS 6 MOUNTED ON A SUPPORT WHEEL 5 THAT AN ELECTRIC MOTOR 13 CAN ROTATE AND WHICH COMPRESS THE TUBE AGAINST A WALL OF ' SUPPORT 3 IN THE ARC OF A CIRCLE PLACED RADIALLY OUTSIDE THE ROLLERS AND DELIVERS THE CONTENTS OF THE TUBE BY A PERISTALTIC MOVEMENT. ESPECIALLY TO SOLVE PROBLEMS OF OVERALL DIMENSIONS AND ROTATION SPEED RELATED TO THE ARRANGEMENT AND SIZE OF THE ROLLER-HOLDER WHEEL 5, THIS WHEEL IS ARRANGED WITH ITS ROTATION AXIS 4 transversely to the SHAFT 13A OF THE ELECTRIC MOTOR 13. THE PUMP CAN IN PARTICULAR BE CARRIED ON PERMANENTLY AS AN ENTERIC PUMP BY AN ARTIFICIALLY FEED PERSON.

Description

2503 799

  The invention relates to a peristaltic pump for medical applications, in particular an enteric pump for artificial feeding, comprising a tube, traversed by the pumped fluid, on a longitudinal section which can act rollers mounted on a support wheel that an electric motor can rotate and compress the tube against an arcuate support wall placed radially outside the rollers and

  repress the contents of the tube by a peristaltic movement.

  Such a pump is known from the German patent application DE-OS 25 00 463 for example. This pump is housed in a substantially cylindrical casing having four parts that follow each other axially: a supply part containing batteries, a middle part for the control devices, a motor part and a pump part that connects to the motor part on the side opposite to the feeding part. The plane of the wheel bearing

  the rollers is perpendicular to the axis of rotation of the electric motor

  and the tube is supported on wall portions, located on the periphery of the path of the rollers, which at the same time constitute the wall of the cylindrical casing at the end considered

of it.

  If the casing of this known pump must remain substantially cylindrical, so that the pump can still be conveniently carried in relatively small overall dimensions, it is not necessary that the diameter of the casing becomes too large. As it is necessary at least room for the tube and its support element between the outer side of the casing and the rollers, the wheel bearing the

  pebbles at its periphery must have in turn a very small diameter.

  This means that the tube must be arranged in a small radius arc around the small wheel, which must rotate at a relatively high speed for the pump to have the desired flow rate. However this high speed of the wheel and rollers produces a lot of noise, which is precisely to proscribe when the patient carries the pump

permanently on him.

  In addition, the load conditions of the tube bent along a small radius are unfavorable, which reduces the service life of the tube, which must reach at least 4000 to 5000 hours. Finally, the conditions of refoulement are also

2503 799

  unfavorable, because the rollers, mounted on the small diameter wheel and therefore following each other at a short distance, can not push back each time a relatively small amount of liquid

by the peristaltic movement.

  However, as the roller wheel is wedged directly to the motor shaft, so that it is driven without reduction to the rotational speed of the motor, the wheel must in any case have a small diameter, even if There was no congestion limitation in the lateral direction. Despite this small wheel diameter, to be able to adjust the pump at low flow rates,

  the engine speed must be able to be reduced to extreme

  low for electric motors, which requires expensive special motors. DC motors powered by commonly used batteries can not be used since they possess

  a starting speed of the order of 100 rpm, which is clearly

  excessively high, even taking into account the small diameter of the

  wheel, so that the pump can provide the desired low flow rates.

  It would certainly be possible to install a gearbox with coaxial input and output shafts having the desired reduction ratio - for example in the form of a planetary gearbox - between the shaft carrying the wheel on the one hand and the shaft of the electric motor on the other hand. Such a gearbox is however relatively bulky, expensive and sensitive to disturbances and it would increase at least the overall axial length of the entire pump, which is already very large because of the arrangement of the pump parts,

  motor, control and power behind each other.

  The invention aims to create a peristaltic pump of the type indicated at the beginning but which allows a flat and compact construction without this requiring to limit the diameter of the wheel

nosepiece.

  According to an essential characteristic of the invention, the axis of rotation of the wheel is transverse to the axis of the electric motor. With this arrangement, the main dimension of the wheel, namely its radial dimension, is placed parallel

  to the direction of the main dimension of the electric motor.

2503 799

  Transversally to these main dimensions, it is therefore necessary

  space for the thickness of the wheel and the thickness or diameter of the electric motor. Thus, regardless of the diameter of the wheel, a very flat construction, so that the pump can be housed in a flat parallelepiped casing which is only a small protrusion when the pump

  is worn on the body of a user. Compared to the thick

  The width of the casing is of secondary importance, so that there is practically no limitation as regards the diameter of the wheel-bearing wheel, which is the determining element for the width of the casing. It is therefore possible to use without disadvantage a wheel with a relatively large diameter, rotating at a slower speed for a given flow rate, which produces a very quiet operation and a smooth and exactly dosed discharge. If the wheel protrudes laterally from the electric motor, in the direction of the width of the casing, if it is of parallelepipedal shape, there is room for the batteries or other devices on both sides of the motor, so good

  that batteries and the like do not require an increase in

  additional width and height. Because the axes of the wheel and the motor are transverse, the wheel can be rotated with a very high reduction ratio of at least 1: 100, preferably more than 1: 500, by a simple pinion wedged on the shaft of the electric motor and meshing with a ring gear on the outer edge of the wheel. The reducer thus formed therefore does not require additional space. It should also be noted that for the peristaltic pump known according to the patent application DE-OS 25 00 463 mentioned in

  Initially, efforts were made to make the support wall as much as possible

  inelastic, so that it does not make uncontrolled movements of spacing or ceding during the compression of the tube by the rollers. The bearing wall of this known pump extends at an angle of about 1800 around the wheel, which carries four uniformly distributed rollers, and is provided on a bearing piece which projects from the two lateral ends of the wheel. wall

2503 799

  of support and ends at these lateral ends by a closing piece. Such a closure piece is necessary because the support piece must form with the closure part the cylindrical outer surface of the pump casing. The known construction provides certainly the elastic deformation of the support piece, in that its curvature can be reduced by the elastic deflection of its ends outwards, so that the closure part and then also the support piece may be removed, for example when the tube needs to be replaced. This deformability is, however, limited to the opening of the bent support piece over 1800 and the part is generally so rigid that the support wall is inelastic during the service of the pump. This construction is at the origin of several disadvantages. During a tube replacement for example, the

  closure piece and the support piece must be removed

  the pump and be placed side-by-side, so that they may be damaged or dirty or even be lost. In addition, the rigid support wall during operation requires an accurate and therefore expensive manufacturing, since, on the one hand, the rollers, mounted non-elastically on the wheel, must compress the tube so strongly in the compression zone that the liquid passage is completely removed and a leakage current is

  impossible, on the other hand, it is necessary to avoid too much compro-

  tube because it could cause permanent damage

  mediate the tube or at least decrease its service life.

  The large circumferential extent of the support wall and the larger circumferential extent of the support piece, necessary to be able to mount the closure piece at the ends of the

  bearing piece, have the disadvantage that the tube is permanently

  nence compressed by at least two rollers and even three rollers sometimes if we also add the transition zones, which leads, for a given operating time, not only to

  a greater load by compression of the tube, so to the shortening

  its duration of service, but also to conditions of refoulement which are not optimal since the quantity of

2503 790

  liquid carried in the tube between successive compression points is relatively small. For a given flow rate, it therefore requires a higher rotational speed of the wheel carrying the rollers, which results in an even greater compressive load of the tube and a further decrease in its service life. The invention therefore also aims to create a pump as indicated at the beginning but with which it is possible to obtain a compressive load that cleans the tube, while excluding with

  certainty of the leakage currents by the compressed zone, independently

  manufacturing tolerances.

  For this purpose, according to another essential characteristic,

  of the invention, which is also applicable independently of that indicated in the foregoing, the support wall is disposed on at least one movable support piece guided in the direction of support and loaded in the direction of the axis rotation of the wheel by an elastic pressure producing the desired compression of the tube. Because the bearing piece is movable in the bearing direction, its distance relative to the rollers is variable and the piece can, depending on the manufacturing tolerances, occupy each time the appropriate position relative to the rollers. Due to the elastic load of the support piece in the direction of the axis of rotation of the wheel, therefore of the rollers compressing the tube, the

  support wall is nevertheless pushed gently towards the rollers.

  The choice of the elastic prestressing of the support piece thus allows, in each position that the part or the support wall takes automatically, a precisely defined compression, ensuring on the one hand the complete closure of the inside of the tube in the compression zone, taking into account the stiffness of the tube material and the desired discharge pressure, but also excluding with certainty compressions stronger than that necessary to achieve this result. It is thus ensured that the required compression, and only this compression there, whatever the

conditions, always be reached.

  If the support wall is to extend over a large arc angle, for example 180, around the periphery of the wheel-bearing wheel,

2503 799

  it is possible to use a plurality of support pieces each arranged movable in the direction of its mean support. However, as a general rule, only one support piece with a bearing wall whose angle of arc on the circumference of the wheel is a little larger than the angle between two rollers which follow, which is roughly equivalent to an arc angle of 1000 if there are four rollers evenly distributed around the circumference of the wheel. It is thus ensured that the tube is always compressed in at least one place, so that the reflux of the liquid to be pumped is excluded and that, at the same time, there are only two compression points in the transfer zone between two rollers and this only periodically and for a short time. This arrangement gives at the same time a maximum flow rate for a given outer diameter and circumferential speed of the wheel. In addition, it is sufficient in this case to provide a single support piece since, when this part is spaced from the periphery of the wheel, the lateral portions of the support wall also move away from the rollers for a distance which is at less than the distance on which the median portion of the wall moves away from this circumference. Another advantage is that the removal of a single support piece from its operating position & a retracted mounting position immediately gives access to the working section of the tube, so that the tube can be removed from the area of the rollers and be

  inspected and / or replaced if the stroke of the support piece is suf-

  large enough to almost completely eliminate the compro-

  sion of the tube in the zone o is at this moment one. roller.

  It is particularly advantageous to provide a

  means for locking the support piece to the retracted mounting position.

  because the workpiece can be moved away from the wheel by a single gesture and both hands are then free to manipulate the tube

  while the support piece is held in its mounting position.

  It is particularly advantageous to provide a release element by which the support piece can be released from its locking position, this element can also be actuated necessarily to the closing of the casing by one of the walls thereof. Thus, when the pump is in the service position, the casing being closed, the support wall is always loaded with

2503 79Z4

  the necessary pressure towards the rollers, which guarantees

  the proper discharge of the liquid, the improper commissioning

  of the pump while the support piece is still locked

  at its mounting position being excluded.

  Other features and advantages of the invention

  will be clearer from the following description of a

  non-limiting embodiment of the invention, and the accompanying drawings, in which: - Figure 1 is a schematic plan view of a peristaltic pump according to the invention, the boot is only indicated by mixed lines; and

  - Figure 2 is a section taken along line II-

II of Figure 1.

  As shown in the drawing, where the peristaltic pump is represented a little larger than life, the pump comprises, as essential functional components: a tube 1 through which the fluid is pumped, a support piece 2 having a wall of 3 support and a wheel 5, being rotatable about an axis 4 and carrying at its periphery rollers 6 uniformly distributed in the direction of the circumference, which are four in this example. When the wheel 5 turns in the direction of

  the arrow 7, the rollers 6 act one after the other on the section

  a workpiece in a circular arc designated 8 of the tube 1, so that each roller 6 compresses the tube 1 against the support wall 3 in a compression zone 9 which advances with the roller 6> so that the liquid is finding in front of this area is forced through the tube in a peristaltic motion. The end 10 of the tube 1, shown on the left in Figure 1, is connected to a reserve of liquid, for example a liq ui food, while the end 11 shown on the right forms somehow the discharge pipe of the peristaltic pump. The ends 10 and 11 are suitably secured - not shown by sleeves or the like of the casing 12 which is only indicated by dashed lines and which constitutes the casing of the pump, so that the tube 1 is suitably held at the entrance and exit of its work section 8 and is correctly

2503 79?

  held in place inside the pump. The ends 10 and

  11 can be connected by tubings not shown pre-

  views on the outside of the box to pipes leading one

  to the fluid reservoir, the other to the patient's body.

  In its active zone, the bearing wall 3 located radially outside the rollers 6 has an arcuate shape which extends in this example over an angle of about 1000, that is to say say a little more than the angle of 900 between two pebbles 6 which follow each other. The beginning of the working section 8 of the tube 1 is thus compressed by a new roller shortly before the previous roller leaves the zone of the bearing wall 3 at the end of the working section 8,

  which suppresses the compression of the tube. The reflux of the pumped liquid

  per is thus excluded and, at the same time, during normal service, there is almost always only one roller 6 which compresses the working section 8, so that unwanted interactions

  of rollers driving back simultaneously are avoided.

  The wheel 5 carrying the rollers 6, which can be made as the latter plastic material, is driven by an electric motor 13 which is powered by unrepresented batteries or similar elements housed in the space designated by 14 on both sides of the motor 13 and which can be connected in known manner to this motor by a control circuit not shown for the variation of the speed of the motor. The electric motor 13, the

  wheel 5 and the support piece 2 are all mounted on a plate 15 -

  especially in metal - which has the shape of a U with a wide

  based. As shown particularly in Figure 2, the portion

  diane 16 of the plate 15 carries for this purpose a sleeve 17, fixed by screwing or spot welding, containing a pad 18 for

  the rotational mounting of an axis 19 on which the wheel 5 is fixed.

  The latter has axially sufficient width to

  provide the stability necessary for the safe transmission of the torque.

  The roller wheel 5 of the example shown is therefore formed of two disks 5a and 5b which are joined by concentric spacer rings 5c and 5d, made of plastic like the disks, and carry at their circumferences axes 6a on which are rotary mounted

  the rollers 6, relatively hard rubber for example.

? 503 795 '

  The wing 20 shown at the top of the drawing plate 15 carries on its outer side the electric motor 13,

  as well as, on either side of it, non-rechargeable batteries

  and is traversed by the drive shaft designated 13a of the engine, or by an extension thereof, on which is keyed, inside the flange 20, a pinion 21. This pinion is in engagement with a ring gear 22 which is arranged in a wheel plane perpendicular to the axis of rotation 4 on the side

  outside of the inner disk 5Ja, on the periphery of this disk.

  By a simple straight toothing, one thus obtains a safe torque transmission with a high transmission ratio between the pinion 21 and the ring gear 22, of 1: 600 for example, so that the electric motor 13 can rotate at high speed desired without requiring a gearbox expensive to produce the considerably lower speed of the wheel 5. When the drive shaft 13a of the motor is guided accordingly, for example in a bushing or the like element not shown in the wing 20, it is possible to rotate the pinion 21 sufficiently stable for the proper transmission of the driving forces

  necessary for the roller wheel 5 without providing a further support

  on the inner side of the wing 20. It is seen that the axis of the drive shaft 13a, thus also the longitudinal extent of a current electric motor and the main dimension of the batteries

  both sides of the motor in space 14, are trans-

  versaux to the axis of rotation of the wheel 5, so parallel to the main dimension of the wheel. All large components are therefore arranged parallel and the thickness of the pump is minimal, as can be seen in the drawing, even if the wheel 5 has a very large diameter, which is desirable to obtain a low quiet walk speed. The lateral dimensions of the pump are chosen essentially according to the diameter of the wheel 5, plus the thickness of the tube 1, so that the width is still minimal considering the desired size of the wheel 5. This construction allows as a whole to house the pump in a parallelepipedal housing 12 of flat shape, as shown in the drawing, which is excellently suited when the pump is to be worn permanently by the patient, being

2503 79: '

  attached to the belt for example, and thus producing a

small protuberance.

  The support piece 2, bearing on its inner side the support wall 3 in an arc of a circle, is mounted movable in the direction of support designated by the double arrow 23 on the dowels

  24 fixed on the wing 25 shown at the bottom of the plate.

  15. The support piece 2 is therefore able to move along the arrow 23, that is to say substantially at right angles to the axis of rotation 4 of the wheel 5. Springs 26 load the support piece 2 in the direction of the axis of rotation 4 of the wheel 5 with a pressure such that the working section 8

  tube 1 is compressed to the right of the roller or rollers, with interrup-

  the passage of the liquid, given the stiffness of the material

  of the tube 1 and the discharge pressure. It is advantageous to use

  a silicone tube 1 with an inside diameter of 3 to 4 mm and a wall thickness of 1 to 1.1 mm, with which it is possible to reach

  a discharge pressure of 0.5 bar or a little more in case of use

  springs 26 exerting on the support piece 2 a force of between approximately 2 N and 4 N. For a rotational speed of

  the roller wheel 5 between 25 and 240 rev / h, this corresponds to

  at a maximum flow rate of 250 ml / h, which is sufficient for all applications, especially enteric feeding, and can be reduced to about 1 / 10th if necessary. Based on a reduction ratio of 1: 600 between pinion 21 and ring gear 22, rotational speeds are obtained for this adjustment range.

  engine speed from 180 to 2500 rpm, so you can use

  read for the electric motor 13 any DC motor

  manufactured in large series. Due to the low speed around

  of the wheel 5, whose diameter will generally be greater than

  50 mm, about 70 mm as in the example shown or even more, the noise will be very low, about 20 dB or less. This means that one hears practically that the light purr of the electric motor 13, which is moreover attenuated by

the boot 12.

  The casing 12 is composed of two parts, an upper part 12a and a lower part 12b, which can be grasped

2503 79 '

  in hollows 12c to pull one out of the other. When removing the portion of the casing 12b shown below in the drawing, the working portion 8 of the tube 1 is exposed and becomes accessible from the outside. When, then, the support piece 2 is pulled against the force of the springs 26. in the direction of the lower flange 25 of the plate 15, the compression of the tube in the compression zone 9 of the roller 6 acting at this time on the tube is removed, so that the tube 1 then applies almost freely against the

  support wall 3. The possible travel of the support piece 2 to the

  against the force of the springs 26, according to the arrow 23, is chosen for this purpose large enough so that the tube 1 can be completely relaxed in the compression zone 9, so that this stroke is slightly larger than the inner diameter

of the tube 1.

  The support piece 2 can be locked in its retracted mounting position so that the tube can be handled without problems, for example for replacement. The pump of the example shown has for this purpose a spring tongue 27 fixed on the wing 25, bearing a nose 28 or a similar element and

  prestressing to take a position where the nose 28 clings to the

  a retaining surface 29 of the support piece 2 for the purpose of

  maintaining the latter in the retracted mounting position.

  When the tongue 27 is fine in unlocking position, against its preload, the nose 28 releases the retaining surface 29, so that the support piece 2, under the thrust of the springs 26, can suddenly resume its service position by

  its displacement in the direction of the axis of rotation of the wheel 5.

  For this unlocking, the pump shown has a release member 30 in the form of a rod passing through the support piece 2, which can be pressed on the front side of the piece 2 and whose opposite end then moves the tongue to spring 27 for unlocking. In order to pocket the peristaltic pump

  put into operation when the support piece 2 occupies its posi-

  With the retracted mounting arrangement, which prevents pumping, the front end 30a of the release member 30 is arranged to be driven by the adjacent wall 12d of the casing portion 12b - which is the lower portion of the housing. boot maker in this

_03 79

  example- so that the tongue 27 is pushed back to its release position. The front end 30a of the release element may have a bevel 30b or a similar conformation to avoid the attachment of the edge of the wall 12d to the closure of the casing. The removal of the portion 12b of the casing of this example therefore gives access to the working portion 8 of the tube 1 and the support piece 2 can be retracted to the mounting position

  o it is blocked automatically by the snapping of the nose 28 der-

  The tongue 27, during this movement, pushes the release member 30 to the left in the representation of Figure 2, so that the front end 30a of this element is sufficiently protruded outside. When, subsequently, the inner portion 12b of the casing is put back in place, the wall 12d,

  by the chamfer 30b, pushes the element 30, so that the tongue

  Gait 27 is discarded, while the nose 28 releases the retaining surface 29, the tab being kept apart. From this moment,

  the part 2 presenting the support wall 3 is exposed to the force -

  whose size can be chosen - springs 26 which

  against the working section 8 of the tube 1 and exert on this section a defined force in the compression zone 9, which force is independent of manufacturing tolerance or the like. So

  in a simple way, on the one hand, that excessive

  of tube 1 in zone 9 are avoided with certainty,

  on the other hand, that the desired compression to stop the flow in the tube 1 in the compression zone 9 is produced

in all cases.

  The invention thus provides in the assembly a peristaltic pump which operates silently and has a low weight and a small volume, so that it can be carried away permanently by patients, for example by patients fed enteric way, without to hinder them in their movements or to obstruct them in a major way. An execution of the pump having the flow rates and the other characteristics indicated above has the overall dimensions of the following casing 12: 146 mm x 65 mm x mm and satisfies all the requirements with regard to the intake exactly dosd following the speed of rotation of food solution.

2503 799

Claims (11)

  1. Peristaltic pump for medical applications, in   particular enteric pump for artificial feeding, com-   taking a tube, traversed by the pumped fluid, on a long stretch of   of which rollers mounted on a wheel of   port that an electric motor can rotate and which compress the tube against an arcuate support wall placed radially outside the rollers and drive the contents of the tube by a peristaltic movement, characterized in that the axis rotating (4)   of the wheel (5) is transverse to the axis (shaft 13a) of the electric motor tramp (13).   2. Pump according to claim 1, characterized in that the wheel (5) carries at its periphery a ring gear (22) which   is engaged with a pinion (21) controlled by the electric motor   (13), so as to produce a reduction ratio of   speed of more than 1: 100, preferably of more than 1: 500.   Pump according to Claim 2, characterized in that the ring gear (22) is arranged in a radial plane with respect to the axis of rotation (4) of the wheel (5) and in that the   pinion (21) is parallel to the axis of the shaft (13a) of the electric motor tramp (13).   4. Pump according to claim 3, characterized in that the pinion (21) is arranged directly on the shaft (13a) of the electric motor (13).   5. Pump according to any one of claims 1 to   4, characterized in that cells or the like are arranged in a space (14) adjacent to the electric motor (13), parallel to this engine.   6. Pump, in particular according to any one of the   1 to 5, characterized in that the support wall (3) is arranged on at least one movable support piece (2) guided in the bearing direction (arrow 23) and loaded in the direction of the axis. of rotation (4) of the wheel (5) by an elastic pressure producing   the desired compression of the tube (1). 2503 799   7. Pump according to any one of claims 1 to 6,   characterized in that the arcuate shape of the wall of ap-   (3) extends over an angle that is slightly larger than   the angle between two rollers (6) which follow.   8. Pump according to any one of claims 1 to 7,   characterized in that the support piece (2) has a mounting position where it can be brought against the elastic force and where it is at a distance from the rollers (6) which is larger   than the inside diameter of the tube (1).   9. Pump according to claim 8, characterized in that   that the support piece (2) is lockable to its mounting position.   10. Pump according to claim 9, characterized in that the support piece (2) is covered in use by a casing wall (12d) and in that a release element (30) of the   blocking of the support piece (2) is loaded in the direction of its posi-   release by this wall (12d) when the casing (12) is closed.   Pump according to any one of claims 2 to 5   and 6 to 10, characterized in that it comprises a plate (15) which is essentially U-shaped, the middle portion (16) of which supports an axis (19) for the rotational mounting of the wheel-roller wheel (5), one of the wings (20) externally carries the electric motor (13) and internally the pinion (21) and the other wing (25) carries   internally the support piece (2) having the support wall (3).