Miniature peristaltic pump

The miniature peristaltic pump (1) of this invention includes a pump module (2) comprising a gear (11) arranged to drive a rotor bearing rollers, said rollers crushing locally at least one tube into which a medicinal preparation may be sucked in at the input (13) and expelled at the output (14) thereof. The gear (11) meshes with a pinion (12) forming part of a motor module (3) adapted to be mounted with or dismounted from the pump module. The motor module comprises a timepiece movement of the type currently employed in a wrist watch, such movement including a stepping motor, an integrated circuit, a quartz resonator and down gearing by means of toothed wheels. An energy cell renders the pump self contained. The pump is intended to be carried on the human body and thus renders unnecessary that the patient recline on a bed.

This invention concerns a miniature peristaltic pump especially adapted to 
be carried on the human body for slow and continuous injection of 
medicinal preparations in the aqueous state, including a pump having a 
rotor borne on a shaft around which are evenly distributed rollers given a 
revolving movement rolling along at least one flexible tube so as to 
compress it against at least one backing which surrounds said tube over a 
predetermined length of arc so as to permit the sucking in and the 
expelling of said medicinal preparation, said shaft being provided with a 
coupling element, a stepping motor driving a down gearing chain bearing at 
its end a power take-off, a control circuit for providing the motor with 
energizing pulses coming from a time base followed by a frequency divider 
and a power cell. 
BACKGROUND OF THE INVENTION 
Peristaltic pumps which permit precise dosage of the liquid to be 
administered, for instance to a patient in the form of a perfusion, are 
known as much in research applications as in therapeutic employment. One 
will find in patent documents U.S. Application No. 4 715 786 and WO 88/10 
372 descriptions of peristaltic pumps, the principle of which is well 
known and which generally consists in employing an elastically deformable 
tube to be locally crushed against a sump by means of a rotor equipped 
with revolving rollers and thus sucking in, then expelling the liquid 
contained in the tube coming from a reservoir. By varying the speed of 
rotation of the rotor, one may modify the pump discharge. Such discharge 
may even be programmed over a time period, this as a function of the 
requirements established by the illness to be cared for or by the 
experiment which is to be carried out. 
Peristaltic pumps equipped with a single tube or flexible pipe exhibit the 
shortcoming of discharging the liquid which they are intended to transport 
in a sinusoidal manner, thus irregularly. In order to overcome this 
problem, there has been proposed the simultaneous employment of two 
coupled pumps provided with two flexible pipes placed in parallel on which 
act respectively two rotors provided with rollers. A first pump of this 
nature is described in the patent document WO 82/04 291 where the rollers 
on one rotor are angularly offset relative to the rollers of the 
neighbouring rotor. A second such pump is described in the patent document 
GB 1 595 901 where the two rotors exhibit coaxial rollers two by two and 
where the flexible pipes are offset relative to one another in a manner 
such that when a roller of the first rotor crushes the first pipe in the 
middle of its active length, the second pipe is simultaneously crushed by 
two rollers of the second rotor at the beginning and at the end of its 
active length. Whatever be the solution chosen, it will be understood 
that, as described, one obtains a much more regular discharge since the 
sinusoidal discharges given by the two pumps taken independently are 
offset in time and compensate one another so as to obtain a substantially 
constant discharge. 
The document Life Support Systems (1983), 1, 23-28 describes a peristaltic 
pump which is implantable into the body. From this particularity there 
ensues the fact that all components of the pump are hermetically 
encapsulated in a case of titanium. The pump reservoir is filled in a 
percutaneous manner by means of a syringe. The driving motor of the pump 
is of the stepping type. It is energized by a time base followed by a 
frequency divider and a battery. The pump is externally programmable by 
means of a control apparatus coupled by magnetic induction to the pump. 
The patent document FR-A-2 479 692 (=U.S. Application No. 4 692 147) also 
describes a peristaltic pump which is implantable into the body, the 
generic characteristics of which respond in all points to those described 
in the preceding paragraph. 
The peristaltic pumps known from the documents cited hereinabove exhibit 
construction principles which generally are closely related to the 
definition given in the first paragraph of this description and which 
partially describes the pump according to this invention. At the same 
time, none of the cited pumps and generally no other pump currently known 
in practice is susceptible to be portable, for instance on the human body 
for the slow and continuous injection of medicinal preparations. The prior 
art pumps are heavy and voluminous and if they are employed for purposes 
of perfusion, are arranged on a table in proximity to a patient prone on a 
bed. 
In contrast to this, the pump according to this invention is portable next 
to the body, this enabling a patient to move around and even to attend to 
his usual occupations. To attain this purpose, the pump of the invention 
is a miniature pump taking up little space. Another aim of the pump 
according to the invention is that of being inexpensive to such a point 
that it may be thrown away following use, thus avoiding all risk of 
contamination. Yet another purpose of the pump according to the invention 
is that of having two modules, a pump module and a motor module which are 
separable by the practitioner himself who could be either a medical doctor 
or a nurse, this in order to enable sterilization of the pump module 
and/or choice of a motor module adapted to the illness to be cared for. 
SUMMARY OF THE INVENTION 
In order to achieve these ends and the advantages which they bring, the 
portable miniature peristaltic pump of the invention is characterized in 
that it includes a first or pump module and a second, or motor module, 
said modules being adapted to be connected to or disconnected from one 
another, the pump module comprising the pump itself provided with its 
coupling element and the motor module comprising the stepping motor, the 
down gearing chain provided with its power take-off, the control circuit, 
the time base, the frequency divider and the power cell, said coupling 
element being engaged with said power take-off when said modules are 
assembled. 
The invention will be understood with the aid of the description to follow 
and which gives by way of example and with the help of the accompanying 
drawings a practical embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows a peristaltic pump 1 in accordance with a preferred embodiment 
of the invention. The pump includes a pump module 2 and a motor module 3. 
As may be seen on the figure, modules 2 and 3 are adapted to be connected 
to and disconnected from one another. For this the pump module bears 
centering studs 4 which are introduced into centering holes 5 pierced in 
the motor module when the two modules are assembled. The pump module bears 
threadings 6 which receive screws 7 thanks to which the modules may be 
fastened to one another. As further shown on FIG. 1, the pump module 2 is 
formed in two parts comprising a pump body 8 and a cover 9. The body of 
the pump and the cover are held together by means of screws 10. The pump 
module 2 is provided with a coupling element, in this case a gear 11, by 
which the pump may be driven and the motor module 3 includes a power 
take-off, in this case a pinion 12, adapted to drive the coupling element 
11 when the two modules are assembled. The pump module 2 further includes 
an input 13 and an output 14 for a medicinal preparation in the aqueous 
state. 
A preferred embodiment of the pump module will now be described having 
reference to FIGS. 2 and 3. This module is equipped with a rotor 80 borne 
on a shaft 14. Rotor 80 includes a first set of rollers 15 revolving along 
a first flexible pipe 16 and compressing it locally against a first 
backing 17. This first backing surrounds the first pipe along a first 
predetermined arc length AC. In an analogous manner, rotor 80 includes 
also a second set of rollers 18 revolving along a second flexible pipe 19 
and locally compressing it against a second backing 20. This second 
backing surrounds the second pipe over a second arc of predetermined 
length DE. FIGS. 2 and 3 show that the rollers 15 and 18 are coaxially 
arranged two by two and that the arcs AC and DE exhibit substantially the 
same length. In the same manner it is seen on FIG. 3 that the outputs of 
pipes 16 and 19 are connected in parallel by means of a Y coupling 21 to 
end up at a common output 14 if the rotor turns in the sense of arrow F. 
It is the same for the common input 13, although the parallel connection 
does not show up on FIG. 3. FIG. 2 further shows that the first and second 
backings 17 and 20 are angularly offset in a manner such that the 
bisectors b.sub.1 and b.sub.2 of angles .alpha. and .beta. which they 
respectively subtend form between them an angle .gamma. which is half of 
the angle (for example the angle .alpha.) formed by two straight lines 
d.sub.1 and d.sub.2 issuing from shaft 14 of the rotor and respectively 
cutting axes 22, 23 of two neighbouring rollers 15. 
This arrangement enables regularizing the pump discharge as has been 
explained hereinabove with reference to document GB 1 595 901. In this 
respect it will be understood that if each set of rollers includes three 
rollers 15, respectively 18, equally distributed about the axis 40 of 
rotor 80, the backings 17 and 20 will be offset by an angle substantially 
equal to 60.degree. which moreover is the case as shown on FIG. 2. 
The backings supporting the pipes against the rotor may be obtained in 
various manners. In the embodiment of FIG. 2, backings 17 and 20 each 
exhibit the form of a hook pivoted at one of its ends, for instance around 
pins 24 and 25 respectively. Hooks 17 and 20 are pressed against pipes 16 
and 19 respectively by means of springs 26 and 27 respectively, themselves 
held in place by screws 28, 29 threaded into the body of pump 8. 
If one now refers to FIG. 3, it will be noticed that the rotor is formed of 
two end plates 30 and 31 between which are maintained the rollers 15 and 
18 adapted to turn around axes 32. Here it will be noted that the rollers 
15 are independent from rollers 18, which permits them to turn at 
different speeds. One benefits from the ends of axes 32 in order to fasten 
the gear 11 to rotor 80. FIG. 3 further shows that the first and second 
backings 17 and 20 are separated by a plate 36 which surrounds rotor 80 
and which is arranged perpendicularly to shaft 14. This plate serves as a 
brace for the backings which thus gives them greater freedom of action. 
The plate also serves as a guide for each of pipes 16 and 19 which it 
maintains at the level of rollers 15 and 18 respectively. This plate is 
not drawn on FIG. 2 in order not to unduly overload said figure. There has 
however been referenced on FIG. 2 housings 33 in which plate 36 is 
supported. FIG. 3 further shows a second plate 34 located under gear 11 
and which also serves as an upper guide for the flexible pipe 16. This 
second plate is not seen on FIG. 2 where, on the other hand, housings 35 
are shown which serve as support points for plate 34. 
The description of the pump module which has just been given is based on 
the employment of two flexible pipes placed in parallel and this for the 
reasons indicated. The invention however is not limited to a pump 
exhibiting two pipes and could exhibit one only or more than two. 
An embodiment of the motor module will now be described having reference to 
FIGS. 1, 3 and 4. In accordance with the invention, the motor module 
includes a stepping motor driving a down gearing chain bearing at its end 
a power take-off shown by pinion 12 on FIG. 1. As has already been 
indicated, pinion 12 is adapted to drive gear 11 of the pump module when 
the two modules are assembled. According to the invention, the stepping 
motor is energized by energy pulses from a control circuit itself 
controlled by a frequency divider receiving a signal from a time base, 
such elements being energized from a DC source provided by a power cell. 
On FIG. 1, the motor module shows a housing 40 serving to accommodate the 
power cell and a housing 41 serving to accommodate the gearing, the motor, 
the control circuit, the frequency divider and the time base. An opening 
42 serves to house a switch for turning on the system or putting it out of 
circuit. FIG. 3 which shows a cross-section of the completely assembled 
pump also shows the housings 40 and 41 as well as the power take-off or 
pinion 12 of the motor module engaged with the coupling element or gear 11 
of the pump module. 
FIG. 4 which is a partial view of the motor module of the pump shows in 
detail a driving mechanism 43 including a movement 44 fastened onto a 
plate 45, this latter being secured to the pump module 3. All of these 
elements find place in the housing 41 sketched on FIG. 1. The movement 44 
includes a stepping motor 46, preferably of the type employed in a 
wristwatch and for which a description of the principle is given, for 
instance in the U.S. Pat. U.S. Application No. 2 909 685. FIG. 4 shows 
that the motor 46 includes a winding 47, a core 48 and a stator 49 
exhibiting two poles separated by a circular opening 50 in which moves a 
diametrally magnetized rotor 51. On the rotor axis is found a pinion 52 
which drives gearing including a kinematic chain of gear elements 
referenced in the order in which they appear in the chain by 53, 54, 55, 
56 and 57. On the axis of gear element 57 will be found the power take-off 
or pinion 12 which has already been mentioned. Preferably the entire 
movement including the motor and the gearing is a timepiece movement such 
as employed for instance in a wristwatch. In this case the wheel set 54 is 
known as the seconds wheel and the wheel set 57 the hours wheel. In this 
special application the output pinion 12 replaces the hours hand. 
As is further shown on FIG. 4, motor 46 is energized by a block IC 
comprising a control circuit, itself commanded by a frequency divider 
receiving the signal furnished by a time base Q. The time base will be 
preferably a quartz oscillator known for its great stability which 
provides the pump with a constant discharge. The block IC is commonly 
formed from a monoblock integrated circuit. A cell or battery B coupled to 
the system by a switch I provides the necessary energy. The control system 
for the operation of the motor is likewise known from the technology 
employed over a long period in wristwatches. One will find a description 
for instance in the U.S. Pat. U.S. Application No. 3 742 697. 
FIG. 4 also shows that the movement 44 has had eliminated therefrom the 
cell, the quartz and the integrated circuit which are normally found at 
the places referenced 60, 61 and 62 respectively. In the embodiment taken 
as an example, it is preferred to place these elements outside the 
movement. 
There will now be given an example of a practical embodiment of the 
invention. The stepping motor as chosen operates correctly up to a 
frequency of about 105 Hz. Starting with a standard timepiece quartz 
regulated at 32'768 Hz, one begins by dividing the frequency by means of 
six divide-by-two circuits, this giving a frequency of 512 Hz which is 
further divided once by a divide-by-five circuit, this resulting in a 
motor energizing frequency of 102.4 Hz. Since the motor as chosen is a 
bipolar single phase motor, its shaft will make two steps per revolution 
and will rotate at the speed of 51.2 revolutions per second. Between the 
shaft of the motor bearing pinion 52 and the shaft of the pump bearing 
gear 11, the reduction is 1:129'600, this giving a speed of rotation of 
the gear 11 of 1 revolution in 42 minutes 11 seconds. With this rotation 
speed, there has been measured an average discharge of 70 mm.sup.3 during 
the same time period. It is evident that the figures as given are an 
example of an embodiment and that the discharge may be modified by varying 
the quartz frequency, the number of divider stages, the reduction ratio 
given by the gear train and/or finally, the type of motor employed. 
The peristaltic pump according to the invention has as main characteristic 
that of being of very small dimensions such that it may be worn or carried 
directly on the body as shown on FIG. 5. Here the pump 1 is placed on the 
abdomen of the body and is held there by means of an adhesive 63. The 
output 14 of the pump is coupled to a hypodermic needle 64 by a tube 65. 
The input 13 of the pump is coupled by means of a tube 66 to a reservoir 
67 containing the medicinal preparation. The reservoir, placed in the 
region of the armpit, is held on the body by means of another adhesive 68. 
It has been seen hereinabove that the discharge of the pump according to 
the invention gives out a small liquid discharge which is a condition for 
its miniaturization. It is thus intended to cure illnesses other than 
diabetes for which stronger discharges are necessary at certain times of 
day. It is not in principle intended to deliver variable discharges over 
the course of time, such discharge however could be interrupted if 
necessary during certain periods thanks to the built-in switch. If the 
performances of the pump are limited, such pump may however be employed in 
numerous cases for which it will be appreciated for its smallness and its 
autonomy. It will be also appreciated for its very low price since it 
comprises only inexpensive components and may be manufactured in large 
quantities, particularly for the part formed by the motor module. 
Accordingly the pump may be thrown away after use. 
It is likewise important that the pump be formed of two separable modules. 
It is known in effect that it is necessary to sterilize the pump before 
employment, which may be effected by gamma rays. The pump module which 
bears no electrical element and is formed almost entirely of plastics 
material, is well adapted to this type of sterilization. On the other hand 
the motor module will not withstand such treatment (motor, integrated 
circuit, etc.). Furthermore, if the modules are separable, it is 
understood that with a single pump module one may employ different motor 
modules differing above all in respect of the speed of rotation of the 
power take-off according to the volume of liquid to be injected. 
It has been explained hereinabove that the pump of the invention generally 
exhibits a very small discharge and it will be understood that the speed 
of rotation of gear 11 is so low that it does not enable priming of the 
pump. To enable this operation, gear 11 includes a series of holes 70 (see 
FIGS. 1 and 3) which are rendered accessible to the practitioner before 
the motor module is coupled to the pump module. By employing the tip of a 
ballpoint pen for instance, the practitioner may turn gear 11 at a speed 
enabling priming of the pump. 
It is further mentioned that the pump may be sealed against dust, natural 
secretions of the body and water thanks to the coating means enveloping 
the entire pump. However, in place of coating one could by means of 
constructions and by means of seals assure sealing of the pump body 8 
relative to the cover 9 and the sealing of the pump module 2 relative to 
the motor module 3. In this latter case one will likewise seal all 
openings such as the input and output 13 and 14, zone 42 where switch I is 
located, and in general all passage holes (screws etc.). 
It has been mentioned hereinabove that at least the pump module is formed 
of plastics material. In a general manner there will be chosen a material 
for both modules which is insensible to attacks by natural secretions of 
the human body.