U.S. patent application number 11/157638 was filed with the patent office on 2006-01-05 for peristaltic pump comprising a bearing member and a counter-member adapted to cooperate with a tube.
This patent application is currently assigned to Millipore Corporation. Invention is credited to Bertrand Engel, Raphael Grinon, Stephane Olivier, Christian Schann.
Application Number | 20060002799 11/157638 |
Document ID | / |
Family ID | 34947891 |
Filed Date | 2006-01-05 |
United States Patent
Application |
20060002799 |
Kind Code |
A1 |
Schann; Christian ; et
al. |
January 5, 2006 |
Peristaltic pump comprising a bearing member and a counter-member
adapted to cooperate with a tube
Abstract
The peristaltic pump (1) comprises: a sensor (53, 57) of the
force exerted between the bearing member (19) and the
counter-member (24) between which a tube (6) is held; and a
processing unit comprising means for determining, from the signal
supplied by the sensor (53, 57), if predetermined conditions
indicative of correct positioning of the tube (6) between the
bearing member (19) and the counter-member (24) have been
satisfied.
Inventors: |
Schann; Christian;
(Oberhausebergen, FR) ; Olivier; Stephane;
(Rosheim, FR) ; Grinon; Raphael; (Ribeauville,
FR) ; Engel; Bertrand; (Dimbsthal, FR) |
Correspondence
Address: |
MILLIPORE CORPORATION
290 CONCORD ROAD
BILLERICA
MA
01821
US
|
Assignee: |
Millipore Corporation
Billerica
MA
|
Family ID: |
34947891 |
Appl. No.: |
11/157638 |
Filed: |
June 21, 2005 |
Current U.S.
Class: |
417/1 |
Current CPC
Class: |
F04B 49/065 20130101;
F04B 43/12 20130101 |
Class at
Publication: |
417/001 |
International
Class: |
F04B 49/00 20060101
F04B049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 30, 2004 |
FR |
0407259 |
Claims
1. Peristaltic pump comprising a rotor incorporating rollers and a
mobile jaw that is provided with a bearing member and assumes: an
open position in which it is moved away from the rotor, the bearing
member then being move away from a fixed counter-member on the pump
(1), with the result that a tube on which said pump must act may be
fitted between the jaw and the rotor, on the one hand, and between
the bearing member and the counter-member, on the other hand, and a
closed position in which the mobile jaw is moved close to the
rotor, which moves the bearing member toward said counter-member,
with the result that said tube is gripped between a curved bearing
surface of the mobile jaw and at least one roller of the rotor, on
the one hand, and between the bearing member and the
counter-member, on the other hand, this pump being characterized in
that it further comprises: a sensor of the force exerted between
the bearing member and the counter-member; and a processing unit
comprising means for determining, from the signal supplied by the
sensor, if predetermined conditions indicative of correct
positioning of the tube between the bearing member and the
counter-member have been satisfied.
2. Peristaltic pump according to claim 1, characterized in that the
force sensor is integrated into the counter-member.
3. Peristaltic pump according to claim 1, characterized in that the
force sensor is integrated into the counter-member and the
counter-member comprises a first assembly that comprise: a base
provided with means for fixing it to the pump; a test body
comprising a curved portion and rigidly connected by one of its
ends to the base and comprising a contact member at its other end;
and a strain gauge applied to the curved portion of the test
body.
4. Peristaltic pump according to claim 3, characterized in that the
counter-member comprises a second assembly identical to and
independent of the first assembly.
5. Peristaltic pump according to claim 1, characterized in that the
processing unit comprises a memory in which a signal-pressure
coefficient is stored, the processing unit being adapted to process
the value of the signal supplied by the force sensor according to
said signal-pressure coefficient to obtain the pressure of the
fluid circulating in the tube.
6. Peristaltic pump according to claim 1, characterized in that the
processing unit comprise a module for compensating creep of the
tube adapted to measure periodically the value of the signal
supplied by the force sensor and to recalibrate the senor
dynamically as a function of the lowest measured value of said
signal.
7. Peristaltic pump according to claim 1, characterized in that the
processing unit comprises a module for filtering pulsation of the
pump.
8. Peristaltic pump according to claim 1, characterized in that the
processing unit is adapted to slave the rotation speed of the rotor
to indications supplied by the force sensor.
9. Peristaltic pump according to claim 1, characterized in that the
processing unit is adapted to stop the pump (1) if the force
exerted between the bearing member and the counter-member exceeds a
predetermined threshold.
10. Peristaltic pump according to claim 1, characterized in that
the pump comprises a motorized device for closing the mobile jaw at
a variable speed.
11. Peristaltic pump according to claim 1, characterized in that
the closure device provides a first or approach speed and a second
or closure speed lower than the approach speed.
12. Peristaltic pump according to claim 1, characterized in that
the force sensor is integrated into the counter-member and the
counter-member comprises a first assembly that comprise: a base
provided with means for fixing it to the pump; a test body
comprising a curved portion and rigidly connected by one of its
ends to the base and comprising a contact member at its other end;
and a strain gauge applied to the curved portion of the test body
and the contact member has a plane bearing surface adapted to come
into contact with the tube.
13. Peristaltic pump according to claim 1, characterized in that
the force sensor is integrated into the counter-member and the
counter-member comprises a first assembly that comprise: a base
provided with means for fixing it to the pump; and a test body
comprising a curved portion and rigidly connected by one of its
ends to the base and comprising a contact member at its other end;
and a strain gauge applied to the curved portion of the test body
and contact member is a rigid member attached to the test body.
Description
[0001] The invention relates to the general field of peristaltic
pumps.
[0002] It relates more particularly to a peristaltic pump
comprising a bearing member and a counter-member between which a
tube on which said pump must act is gripped.
[0003] A peristaltic pump, as used in the medical field in
particular, is a pump whose rotor is provided incorporating rollers
that progressively compress the cross section of an elastic tube to
move a liquid along the tube.
[0004] This kind of pump is therefore used to circulate a fluid
inside a tube by operating only on the tube, without coming into
contact with the liquid. This type of pump is therefore suitable
for any application requiring the fluid to remain in a confined
atmosphere, for example to avoid contamination of the fluid when
working in a sterile environment. A peristaltic pump is generally
adapted to operate in an environment where the concept of sterility
is of primordial importance. The pump must therefore not only
fulfill its function of circulating a fluid and preventing its
contamination by the environment, but also avoid contamination of
the environment by the pump itself. The various components of the
pump must therefore be easy to clean, where appropriate by being
demountable, at the same time as ensuring a perfect seal.
[0005] A peristaltic pump typically comprises a rotor comprising
rollers at its periphery and a mobile jaw adapted to assume an open
position, in which it is moved away from the rotor so that an
elastically deformable tube on which the pump has to act may be
placed between the jaw and the rotor, and a closed position, in
which the mobile jaw is moved toward the rotor so that the tube is
gripped between a curved bearing surface on the mobile jaw and at
least one roller of the rotor.
[0006] Peristaltic pumps of the above kind are known in the art in
which the mobile jaw comprises an excrescence formed by a bearing
member and in which the pump body is provided with a counter-member
disposed so that, when the jaw is in its open position, the member
is moved away from the counter-member and, when the mobile jaw is
in its closed position, the bearing member is moved toward the
counter-member so that, when a tube is fitted into the pump, the
tube is gripped between the bearing member and the counter-member.
This gripping action generally has the function of holding the tube
in place while the pump is operating.
[0007] The peristaltic pumps available at present generally allow
visual inspection of the correct position of the tube between the
rotor and the mobile jaw when the latter is in the closed position.
Similarly, correct circulation of the fluid inside the tube may be
monitored visually or automatically on the upstream and/or
downstream side of the pump.
[0008] The object of the invention is to improve the above type of
pump.
[0009] To this end, the invention provides a peristaltic pump
comprising a rotor incorporating rollers and a mobile jaw that is
provided with a bearing member and assumes: [0010] an open position
in which it is moved away from the rotor, the bearing member then
being moved away from a fixed counter-member on the pump, with the
result that a tube on which said pump must act may be fitted
between the jaw and the rotor, on the one hand, and between the
bearing member and the counter-member, on the other hand, and
[0011] a closed position in which the mobile jaw is moved close to
the rotor, which moves the bearing member toward said
counter-member, with the result that said tube is gripped between a
curved bearing surface of the mobile jaw and at least one roller of
the rotor, on the one hand, and between the bearing member and the
counter-member, on the other hand, [0012] this pump being
characterized in that it further comprises: [0013] a sensor of the
force exerted between the bearing member and the counter-member;
and [0014] a processing unit comprising means for determining, from
the signal supplied by the sensor, if predetermined conditions
indicative of correct positioning of the tube between the bearing
member and the counter-member have been satisfied.
[0015] The above kind of pump therefore has access at all times to
information relating to the force that is exerted by the tube when
it is fitted into the pump. This force being representative of the
elastic behavior of the combination of the tube and the liquid that
it conveys, various measurement or monitoring parameters can be
monitored in this way.
[0016] Firstly, the sensor may provide information relating to the
presence or the absence of a force exerted between the bearing
member and the counter-member.
[0017] The processing unit therefore has access to information
indicating that the tube is in place or, to the contrary, that a
misoperation has occurred since the tube is not in position between
the bearing member and the counter-member.
[0018] To obtain the best results, the force sensor may be
integrated into the counter-member.
[0019] In this case, the counter-member may comprise a first
assembly that comprises: [0020] a base provided with means for
fixing it to the pump; [0021] a test body comprising a curved
portion and rigidly connected by one of its ends to the base and
comprising a contact member at its other end; [0022] a strain gauge
applied to the curved portion of the test body.
[0023] The counter-member may also comprise a second assembly
identical to and independent of the first assembly in order to be
able to carry out independent measurements relating to the two
passages of a dual passage tube.
[0024] According to one preferred feature of the invention, the
processing unit comprises a memory in which a signal-pressure
coefficient is stored, the processing unit being adapted to process
the value of the signal supplied by the force sensor according to
said signal-pressure coefficient to obtain the pressure of the
fluid circulating in the tube.
[0025] Thus the sensor may provide information relating to the
pressure of the fluid circulating in the tube. The processing unit
then has access to a conversion coefficient for the force measured
by the fluid pressure sensor. The above kind of pump may therefore
provide a display of the instantaneous pressure of the fluid
circulating in the tube.
[0026] For enhanced measurements, the following features may be
implemented independently of each other: [0027] the processing unit
may comprise a module for compensating creep of the tube adapted to
measure periodically the value of the signal supplied by the force
sensor and to recalibrate the sensor dynamically as a function of
the lowest measured value of said signal; [0028] the processing
unit may comprise a module for filtering pulsation of the pump;
[0029] the pump may comprise a motorized device for closing the
mobile jaw at a variable speed; [0030] the closure device may
provide a first or approach speed and a second or closure speed
lower than the approach speed; [0031] the contact member may have a
plane bearing surface adapted to come into contact with the tube;
[0032] the contact member may be a rigid member attached to the
test body.
[0033] Also, the pump may have additional functions by virtue of
the following features, which may be implemented independently of
each other: [0034] the processing unit may be adapted to slave the
rotation speed of the rotor to indications supplied by the force
sensor; [0035] the processing unit may be adapted to stop the pump
if the force exerted between the bearing member and the
counter-member exceeds a predetermined threshold.
[0036] Other features and advantages of the invention will become
apparent in the light of the following description of a preferred
embodiment of the invention, which is given by way of nonlimiting
example and with reference to the appended drawings, in which:
[0037] FIG. 1 is a perspective view of a peristaltic pump and its
accessories ready for operation;
[0038] FIG. 2 is a bottom perspective view of a protective cap
placed on the top of the pump shown in FIG. 1;
[0039] FIG. 3 is a plan view of the pump shown in FIG. 1 when the
protective cap shown in FIG. 2 has been removed;
[0040] FIG. 4 shows a rotor incorporating rollers that is visible
on top of the pump in FIG. 3;
[0041] FIG. 5 is a view similar to FIG. 3 when the rotor shown in
FIG. 4 has been removed;
[0042] FIG. 6 is a different perspective view of the pump shown in
FIG. 1;
[0043] FIG. 7 is a view to a larger scale of the framed portion VII
of FIG. 6;
[0044] FIG. 8 is a view in longitudinal section of the top of the
pump shown in FIGS. 1 and 6, showing the placing of the tube into
the protective cap;
[0045] FIG. 9 is a perspective view showing manual fitting of the
tube into the pump shown in FIGS. 1 and 6;
[0046] FIG. 10 is a diagrammatic view similar to FIG. 9 showing
lateral adjustment of the tube shown in FIG. 9;
[0047] FIG. 11 is a perspective view of the head of the pump shown
in FIG. 3;
[0048] FIG. 12 is a perspective view similar to FIG. 11 also
showing the mobile jaw shown in FIG. 2;
[0049] FIG. 13 is a side view of the assembly shown in FIG. 12 in
section on a plane passing through the rotor incorporating rollers
and a cam actuating the mobile jaw;
[0050] FIGS. 14 to 16 are plan views of the pump head shown in FIG.
12, showing the mobile jaw in different positions;
[0051] FIGS. 17 to 19 are views from below, from the side, and from
in front, respectively, of the counter-member shown in FIG. 12,
facing a bearing member of the mobile jaw;
[0052] FIGS. 20 to 22 show the counter-member, in a similar manner
to FIGS. 17 to 19, but after receiving a treatment intended to seal
it;
[0053] FIG. 23 is a view in longitudinal section of the
counter-member shown in FIG. 18, showing the cooperation between
the counter-member, the bearing member and the pipe, which in this
figure is seen in section; and
[0054] FIG. 24 is a diagram representing the disposition of the
force sensor and the processing unit and their connection to
certain elements of the pump.
[0055] FIG. 1 shows a peristaltic pump 1 in one of the applications
of this type of pump.
[0056] In the present example, the pump 1 comprises accessories
such as a bottle rack 2 and a flow drawer 3. This configuration is
used to pump the liquid contained in a bottle 4 toward two
containers 5 through a tube connected at one end to the bottle 4
and at the other end to the containers 5.
[0057] In this example the tube 6 comprises two separate passages
sealed with respect to each other and connected to each other by a
longitudinal web 7 that is easy to cut.
[0058] The peristaltic pump 1 comprises a pump body 8 on which are
disposed a display 9 and control keys 10.
[0059] The pump 1 also comprises a pump head 11 (shown in FIG. 3)
which is covered by a protective cap 12 in FIG. 1.
[0060] FIG. 2 is a bottom perspective view of the protective cap 12
when it has been removed from the pump 1. The protective cap 12
comprises an envelope 13 in the form of a cover adapted to cover
the mobile elements of the pump head 11 to prevent the user coming
into contact with them. The envelope 13 comprises a straight groove
14 of sufficient width for the tube 6 to slide therein.
[0061] A mobile jaw 15 is fixed to the inside wall of the envelope
13 by three screws 16. The general shape of the mobile jaw 15 is
that of a crescent moon, the inside wall of its curved portion
comprising a curved bearing surface 17 of circular arc shape. On
respective opposite sides of this bearing surface 17 the mobile jaw
15 comprises a tooth 18 and a bearing member 19, both adapted to
cooperate with the tube 6, like the bearing surface 17.
[0062] The mobile jaw 15 further comprises a hole 20 through the
wall of the envelope 13 (see FIG. 1).
[0063] A round hole 21 communicating with an oblong hole 22 is also
formed in the thickness of the mobile jaw 15. In FIG. 13, which
shows the profile of the oblong hole 22, it is apparent that the
latter comprises a shoulder 22' substantially halfway through the
thickness of the mobile jaw 15. The round hole 21 does not include
this shoulder.
[0064] FIG. 3 shows the pump head 11 when the protective cap 12 has
been removed. The pump head 11 takes the form of a plate on which
are fixedly mounted a counter-member 24, a stop pin 25, and a shaft
23 adapted to be inserted into the hole 20 in the mobile jaw 15 to
enable the jaw to rotate.
[0065] The pump head 11 also receives a rotatably mounted rotor 26
incorporating rollers and a plate 27 from which projects an
eccentric finger 28.
[0066] FIG. 4 represents the rotor 26 incorporating rollers when
removed from the pump 1. The rotor 26 comprises two flanges 29
between which are rotatably mounted three cylindrical rollers 30
and two centering rollers 31, the cylindrical rollers 30 being
regularly spaced at 120.degree. to each other around the contour of
the flanges 29.
[0067] The flange 29 that is the upper flange in FIG. 4 comprises a
flat 32.
[0068] The disposition of the cylindrical rollers 30, the centering
rollers 31 and the flat 32 may be seen in FIG. 14.
[0069] FIG. 5 shows the pump head shown in FIG. 3 when the rotor 26
has been removed. This figure shows a drive shaft 33 which drives
rotation of the rotor 26 to fulfill the main function of the pump
1.
[0070] FIG. 6 is a perspective side view of the pump 1, a framed
portion VII of this figure showing the cooperation of the tube 6
and the cap 12.
[0071] FIG. 7, which is a view to a larger scale of the framed
portion VII of FIG. 6, shows the portion of the groove 14 in which
the tube 6 is engaged. This portion of the groove 14 is delimited
by a bottom 35 in the shape of a circular arc and two facing
lateral walls 36. Each of these lateral walls 36 comprises a
retaining boss 37, the two bosses 37 being disposed
face-to-face.
[0072] The portion of the groove 14 visible in FIG. 7 forms a
locating member adapted to receive the tube 6 when the latter is
pressed into it and to enable sliding of the tube relative to the
longitudinal axis along which it extends, in other words parallel
to itself.
[0073] Note that when the tube 6 is pressed into this portion of
the groove 14 (see FIG. 9) to obtain the assembly shown in FIG. 7,
the tube 6 first slides down the lateral walls 36, until its lower
passage comes into contact with the bosses 37, which creates a hard
point to be overcome in order to press the tube 6 all the way in.
The user then continues to press in the tube 6, which elastically
deforms the lower passage of the tube, which then takes up a
position facing the bottom 35. The web 7 of the tube 6 takes up a
position between the two bosses 37, which retains the tube 6 in the
direction of the portion of the groove 14 shown in FIG. 7.
[0074] Although the lower passage of the tube 6 is retained in its
housing by the bosses 37, a clearance remains between the tube 6
and the locating member, which allows the sliding previously
referred to (see FIG. 10).
[0075] The tube 6 is also removed by elastically deforming the
lower passage of the tube 6, which likewise overcomes the hard
point.
[0076] FIG. 8 shows in section the position of the tube 6 as just
described.
[0077] FIG. 11 is a perspective view of the pump head 11 in the
FIG. 3 configuration.
[0078] FIG. 12 shows the pump head 11 when the mobile jaw 15 has
been fitted; this figure shows the jaw separated from the cover 12,
in order to show the cooperation of the mobile jaw 15 with the
components mounted on the pump head 11.
[0079] FIG. 13 is a view in section of the assembly shown in FIG.
12 and shows in particular the mounting of the plate 27 on the pump
head 11.
[0080] The plate 27 is fastened to a drive shaft 38 that is mounted
on bearings and rotates relative to the pump head 11. The shaft 38
is fastened to a gear 39 meshing with a worm gear 40 that is driven
in rotation by a motor (not shown).
[0081] FIGS. 14 to 16 are plan views of the assembly shown in FIG.
12 in three particular positions of the mobile jaw 15 defined by
the eccentric finger 28, that is to say by the angular position of
the plate 27.
[0082] FIG. 14 shows the eccentric finger 28 in a position allowing
the mobile jaw 15 to be fitted to the pump head 11.
[0083] In FIG. 15, the mobile jaw 15 is in the same position as in
FIG. 14 but the eccentric finger 28 is in a position in which it
locks the mobile jaw 15 and prevents it from being extracted from
the pump head 11.
[0084] FIG. 16 represents the mobile jaw when closed by the
eccentric finger 28.
[0085] The successive positions represented in FIGS. 14 to 16 are
not visible from the outside in normal use of the pump 1, this
region being covered by the cap 12 that is normally fitted over the
jaw 15.
[0086] FIGS. 17 to 19 are various views of the counter-member 24
that is mounted on the pump head 11.
[0087] Referring to FIG. 19, the counter-member comprises an upper
test body 41, a lower test body 42, and two flanges 43 which
connect the test bodies 41, 42 to each other and whose shape
follows the contour of the test bodies 41, 42.
[0088] FIG. 18 shows the shape of the flanges 43 forming the
lateral walls of the counter-bearing 24. The flanges 43 are rigidly
fixed to each of the test bodies 41, 42 by a locating pin 44 and a
fixing screw 45.
[0089] The FIG. 17 bottom view also shows the surface of the lower
test body 42 that is fixed to the pump head 11. This surface
incorporates a cable orifice 46 between two tapped bores 47 in
respective bosses 48.
[0090] The counter-member 24 further comprises an upper contact
member 49 and a lower contact member 50 rigidly fixed to the upper
test body 41 and the lower test body 42, respectively.
[0091] Given the position of the pins 44 and the screws 45 securing
the test bodies 41, 42 to the flanges 43, the test body 41, 42 may
be deformed when a force is applied to the contact members 49,
50.
[0092] FIGS. 20 to 22 are views of the counter-member 24 analogous
to FIGS. 17 to 19; here the counter-member 24 comprises a resilient
seal 51 that fills up the interstices between the flanges 43 and
the test bodies 41, 42 fitted with their contact members 49, 50.
The resilience of this seal provides the sealing effect and at the
same time allows relative movement of the test bodies 41, 42 and
the flanges 43. The material of the resilient seal 51 must have a
negligible stiffness compared to that of the test bodies 41, 42 and
the flanges 43. The test bodies 41, 42 may be made from a high
strength martensitic stainless steel, for example, conforming to
the French standard AFNOR Z40 CNV 14, and tempered/annealed to an
HRC hardness of 45, whereas the flanges 43 and the contact members
49, 50 may be made of ordinary stainless steel; in this case the
resilient seal 51 may be made of silicone. Generally speaking, all
interstices and orifices between the test bodies 41, 42, the
contact members 49, 50 and the flanges 43 may be filled in by this
kind of seal, to obtain a perfect seal.
[0093] FIG. 23 is a side view of the counter-member 24 in
longitudinal section, showing the shape of the test bodies 41,
42.
[0094] Each of the test bodies comprises a base 52 from which
extends a curved portion 53 which has at its end a dovetail mortise
54 in which a dovetail tenon 55 on the corresponding contact member
49, 50 engages. Each base 52 comprises transverse holes 56 for
inserting the pin 44 and the screw 45 and an orifice 56' for fixing
a rear wall (not shown).
[0095] Each of the test bodies 41, 42 has a strain gauge 57 fixed
to the inside wall of the curved portion 53. The strain gauges 57
are adapted to measure deformation of the curved portion 53 to
which they are fixed. Such deformation may occur when the
counter-member 24 is fixed to the pump head 11 by screws inserted
into the tapped holes 47 and a force is exerted on one of the
contact members 49, 50.
[0096] Note that deformation of the curved portion 53 of one of the
test bodies is independent of deformation of the curved portion 53
of the other test body, since the test bodies 41, 42 are connected
only at their base 52, via the flanges 43.
[0097] The strain gauges may be connected into a Wheatstone bridge,
for example, in a manner that is well known in the field of
mechanical engineering.
[0098] Cables (not shown) passing through the orifice 46 connect
each of the gauges 57 to the control circuitry of the pump 1.
[0099] FIG. 24 is a diagrammatic representation of a processing
unit 58 connected to the counter-member 24 and various components
of the pump 1, such as the motor driving the rotor 26, the motor
driving the eccentric finger 28, input peripherals such as the keys
10, and output peripherals such as the display 9.
[0100] The processing unit 58 comprises a module 59 for
compensating creep of the tube 6, a module 60 for controlling
closing of the mobile jaw 15, and a module 61 for filtering
pulsation of the pump 1.
[0101] The functions of the processing unit, whose operation is
explained hereinafter, may be provided by appropriate electronic
circuitry or by an appropriately programmed data processing
device.
[0102] The peristaltic pump 1 that has just been described operates
in the manner indicated hereinafter.
[0103] When the pump 1 is started, the mobile jaw 15 is in the
position shown in FIG. 15, which corresponds to the position of the
cap 12 shown in FIGS. 9 and 10, and the rotor 26 is also in the
position shown in FIG. 15, with the flat 32 disposed so that a
rectilinear passage is formed between the rotor 26 and the jaw 15.
The locating members of the cap 12 are then aligned with this
rectilinear passage.
[0104] First of all, a tube 6 is fitted to the pump 1. To this end,
as shown in FIG. 9, the user holds the tube 6 in both hands and
inserts it into the groove 14. Because of the bosses 37, this
pressing in maneuver has to overcome a hard point, as previously
explained, for the tube 6 to reach the appropriate position in the
locating members formed at each end of the groove 14, as shown in
FIG. 7.
[0105] Referring to FIG. 10, the user may then slide the tube 6
laterally, in either direction, to adapt the length of tube
available on either side of the cover 12 as a function of the
accessories to which the tube 6 is connected (see FIG. 1).
[0106] Once this operation has been effected, intervention of the
user insofar as the positioning of the tube 6 in the pump 1 is
concerned is no longer necessary.
[0107] Using the control keys 10, the user indicates that he wishes
to start the pump 1, which drives rotation of the plate 27 via its
drive system until the mobile jaw 15 reaches the position shown in
FIG. 16, in which the tooth 18 of the jaw 15 clamps the web 7 of
the tube 6 against the immobilizing pin 25.
[0108] When this position is reached, the motor stalls and draws a
higher current. When this consumption peak is detected, the motor
is stopped.
[0109] As the jaw 15 closes, the tube 6 is wrapped around the rotor
26 and at the same time slides as required in the locating members
of the cap 12.
[0110] The tube 6 is finally held on either side of the rotor 26 by
the cooperation of the tooth 18 and the immobilizing pin 25, on the
one hand, and by the cooperation of the bearing member 19 and the
counter-member 24, on the other hand, which lightly grip both
passages of the tube 6.
[0111] The mobile jaw 15 is held in this closure position because
of the irreversible nature of the system comprising the wheel 39
and the worm 40. The pitch and the helix angle of these components
are chosen, in a manner that is well known in the art of mechanical
engineering, so that rotation of the worm 40 drives the wheel 39
but rotation of the wheel 39 is not able to drive rotation of the
worm 40.
[0112] When the tube 6 has been inserted in this way, the rotor 26
may be rotated to start circulating the fluid contained in the tube
6 thanks to the movement of the rollers 30.
[0113] When the pump 1 is operating, the safety of the user is
ensured by the fact that the mobile jaw 15 is in the FIG. 16
position, that is to say in a position in which removal of the
combination of the mobile jaw and the protective cap is prevented
by the eccentric finger 28 and the shoulder 22' in the oblong hole
22 in the mobile jaw 15. It is also impossible to remove the cap 12
when the mobile jaw 15 is in the FIG. 15 position, that is to say
when the rotor 26 is not moving but the pump 1 is powered up.
[0114] On the other hand, when the pump 1 is powered down, the
eccentric finger 28 resumes the position shown in FIG. 14, which
releases the combination of the mobile jaw and the protective cap,
for example to allow cleaning of the components of the pump head
11.
[0115] The pump 1 further comprises means for obtaining, via the
counter-member 24, information relating to the tube 6 and to the
circulating fluid and to operate accordingly on the pump 1.
[0116] The counter-member 24 is connected to a processing unit
(FIG. 24) that stores in a memory a signal-pressure coefficient and
is adapted to derive the pressure of the fluid circulating in the
tube 6 from this signal-pressure coefficient and the voltage
delivered by the strain gauges 57 (which is representative of the
deformation of the corresponding curved portion 53).
[0117] Once the tube has been fitted, and with the pump head in the
FIG. 16 position, the processing unit first verifies the presence
of the tube 6 and its correct placement. To this end, deformation
of the curved portions 53 must be confirmed by confirming that the
distance between the counter-member 24 and the bearing member 19 of
the jaw 15 in the closed position is less than the width of the
tube 6 (see FIG. 23).
[0118] If the presence of the tube 6 is not detected, the pump 1
does not start and displays an error message.
[0119] Once the tube has been positioned correctly and the pump is
operating, the processing unit 58 supplies to the output
peripherals the instantaneous pressure of the fluid in each of the
passages of the tube 6, independently of each other.
[0120] The signal-pressure coefficient is determined empirically,
during a preliminary calibration phase, by installing a tube with
known characteristics in the pump 1 and applying to it a known
pressure. The voltage delivered by the strain gauges 57 is then
read off; the pressure corresponding to this value being known, the
coefficient may be determined. It may be determined for each new
tube used. An average value may be obtained by subjecting a
plurality of tubes to this test and determining from the test
results a mean coefficient valid for all the tubes.
[0121] The processor unit 58 may use the measured pressure of the
fluid in the tube 6 for the following supplementary
applications.
[0122] The processing unit 58 includes a module 59 for compensating
creep of the tube 6, which improves the reliability of the
measurements. To this end, at regular intervals, for example every
20 milliseconds, the module 59 measures the voltage supplied by the
strain gauges 57 and effects a dynamic calibration, from one
measurement to the next, taking the lowest voltage as the reference
value for calculating the zero pressure.
[0123] The processing unit 58 also includes a module 60 for
controlling closure of the mobile jaw 15 that is adapted to
regulate the speed of the mobile jaw 15 when it moves from its open
position to its closed position, leading to compression of the tube
6 between the bearing member 19 and the counter-member 24.
Tightening the mobile jaw 15 too quickly disturbs the pressure
measurement, because of the elasticity of the tube 6.
[0124] The module 60 may therefore slow down the closing of the
mobile jaw (i.e. slow down the motor of the eccentric finger 28) if
the pressure measurement is disturbed.
[0125] The module 60 may further be programmed to start the closure
of the mobile jaw 15 at a high speed and then to clamp the tube 6
at a lower speed, once the tube 6 reaches the vicinity of the
counter-member 24.
[0126] The processing unit 58 further comprises a module 61 for
filtering pulsation of the pump 1. The movement of the rotor 26
acting on the tube 6 during the operation of the pump 1 causes
cyclic disturbances to the pressure measurement, these disturbances
depending on the rotation frequency of the rotor 26.
[0127] The module 61 applies electronic filtering, for example by
means of a low-pass RC filter setting a cut-off frequency.
[0128] In the present example, the rotation speed of the rotor 26
is 240 rpm and the rotor comprises three rollers, which corresponds
to an angular frequency of 12 Hz. A cut-off frequency of 1.5 Hz may
then be defined by an appropriate RC filter; this value gives good
results.
[0129] The processing unit 58 may also slave the rotation speed of
the rotor 26 to the measured pressure of the fluid in the tube 6.
For example, if the processor unit 58 has information relating to
the permitted maximum pressure in the tube 6, the rotation speed of
the pump may be increased to the maximum and then reduced on
demand, if the pressure in the tube 6 approaches its permitted
maximum value.
[0130] Similarly, by indicating abnormal variations in fluid
pressure, the processing unit 58 may detect incorrect flow of the
fluid in the tube 6, linked to clogging of the tubes, for
example.
[0131] Variants of the device may be envisaged that do not depart
from the scope of the invention. In particular, the tube 6 may
comprise a single passage or more than two passages, the
counter-member comprising as many test bodies as there are
passages.
* * * * *