U.S. patent application number 12/965185 was filed with the patent office on 2012-03-01 for peristaltic hose pump.
This patent application is currently assigned to W.O.M. WORLD OF MEDICINE AG. Invention is credited to Heinz Hemesath, Claudia Karkoschka, Stefan Kurbis, Thomas Merzhauser, Joachim Sasse, Peter Zentner.
Application Number | 20120051943 12/965185 |
Document ID | / |
Family ID | 43501511 |
Filed Date | 2012-03-01 |
United States Patent
Application |
20120051943 |
Kind Code |
A1 |
Merzhauser; Thomas ; et
al. |
March 1, 2012 |
PERISTALTIC HOSE PUMP
Abstract
The invention concerns a peristaltic hose pump comprising a
roller wheel (1) rotatable about a roller wheel axis (D), which
roller wheel has rollers that are mounted thereon (2), the roller
wheel rotation axes (R) of which are arranged on a circle
concentric with the roller wheel axis (D), the rollers (2) partly
projecting beyond the roller wheel (1), comprising a hose (3),
which has a flexible and elastic pump segment (4), and the pump
segment (4) being fixable in the axial direction at its two
opposite ends (5, 6) by means of one fixing point (P1, P2) each,
and the pump segment (4) being guided around the roller wheel (1)
under elastic tension, wherein the length (L1) of the pump segment
(4) when not under tension in proportion to the distance (A) of the
fixing points (P1, P2) to the roller wheel rotation axis (D) is
adjusted with the provision that while the roller wheel (1) is
stationary and when applying a fluid pressure in the range from 10
to 400 mbar to one end (P1, P2) of the pump segment (4), a flow of
the fluid of at least 0.01 1/min through the pump segment (4) is
obtained.
Inventors: |
Merzhauser; Thomas; (Berlin,
DE) ; Sasse; Joachim; (Falkensee, DE) ;
Kurbis; Stefan; (Mahlow, DE) ; Zentner; Peter;
(Berlin, DE) ; Hemesath; Heinz; (Berlin, DE)
; Karkoschka; Claudia; (Berlin, DE) |
Assignee: |
W.O.M. WORLD OF MEDICINE AG
Berlin
DE
|
Family ID: |
43501511 |
Appl. No.: |
12/965185 |
Filed: |
December 10, 2010 |
Current U.S.
Class: |
417/53 ;
417/476 |
Current CPC
Class: |
F04B 43/1253 20130101;
F04B 43/12 20130101; F04B 49/035 20130101; F04B 2205/01 20130101;
F04B 49/24 20130101; F04B 49/22 20130101; F04B 2205/09
20130101 |
Class at
Publication: |
417/53 ;
417/476 |
International
Class: |
F04B 43/12 20060101
F04B043/12 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 11, 2009 |
DE |
102009058279.7 |
Claims
1. A peristaltic hose pump comprising a roller wheel rotatable
about a roller wheel axis (D), which roller wheel has rollers that
are mounted thereon, the roller wheel rotation axes (R) of which
are arranged on a circle concentric with the roller wheel axis (D),
the rollers partly projecting beyond the roller wheel, comprising a
hose, which has a flexible and elastic pump segment, and the pump
segment being fixable in the axial direction at its two opposite
ends by means of one fixing point (P1, P2) each, and the pump
segment being guided around the roller wheel under elastic tension,
wherein the length of the pump segment when not under tension in
proportion to the distance of the fixing points to the roller wheel
rotation axis is adjusted with the provision that while the roller
wheel is stationary and when applying a fluid pressure in the range
from 10 to 400 mbar to one end (P1, P2) of the pump segment, a flow
of the fluid of at least 0.01 1/min through the pump segment is
obtained.
2. The peristaltic hose pump according to claim 1, wherein the
distance of at least one fixing point to the roller wheel axis is
adjustable.
3. The peristaltic hose pump according to claim 1, wherein while
the roller wheel is stationary and when applying a fluid pressure
in the range from 10 to 300 mbar, preferably from 10 to 200 mbar to
one end of the pump segment, a flow of the fluid from 0.01 1/min to
1 1/min, preferably to 0.5 1/min is obtained.
4. The peristaltic hose pump according to claim 1, wherein a bypass
line with a pressure-controlled bypass valve is arranged between
the regions of the ends of the pump segment.
5. The peristaltic hose pump according to claim 4, wherein the
bypass valve opens at a pressure from 100 to 500 mbar, preferably
200 to 400 mbar, most preferably 300 to 350 mbar.
6. The peristaltic hose pump according to claim 4, wherein the
minimum clear cross-section of the bypass line with opened bypass
valve is 10 to 100%, preferably 20 to 50%, of the clear
cross-section of the pump segment when not under tension.
7. The use of a peristaltic hose pump according claim 1 for
generating a fluid flow through a medical instrument 11, wherein a
fluid source is connected at a feeding side of the hose, wherein
the medical instrument is connected at a pressure side of the hose,
and wherein the roller wheel is driven with a preselected and
constant speed for feeding the fluid from the feeding side to the
pressure side.
8. The use of a peristaltic hose pump according to claim 7, wherein
the fluid source is a fluid container, which is arranged,
preferably by 0.1 to 2 m, most preferably 0.1 to 1 m, above the
higher end of the pump segment, the fluid container communicating
with the feeding side of the hose without interposed pump.
9. The peristaltic hose pump according to claim 2, wherein while
the roller wheel is stationary and when applying a fluid pressure
in the range from 10 to 300 mbar, preferably from 10 to 200 mbar to
one end of the pump segment, a flow of the fluid from 0.01 1/min to
1 1/min, preferably to 0.5 1/min is obtained.
10. The peristaltic hose pump according to claim 5, wherein the
minimum clear cross-section of the bypass line with opened bypass
valve is 10 to 100%, preferably 20 to 50%, of the clear
cross-section of the pump segment when not under tension.
11. The use of a peristaltic hose pump according claim 2 for
generating a fluid flow through a medical instrument 11, wherein a
fluid source is connected at a feeding side of the hose, wherein
the medical instrument is connected at a pressure side of the hose,
and wherein the roller wheel is driven with a preselected and
constant speed for feeding the fluid from the feeding side to the
pressure side.
12. The use of a peristaltic hose pump according claim 3 for
generating a fluid flow through a medical instrument 11, wherein a
fluid source is connected at a feeding side of the hose, wherein
the medical instrument is connected at a pressure side of the hose,
and wherein the roller wheel is driven with a preselected and
constant speed for feeding the fluid from the feeding side to the
pressure side.
13. The use of a peristaltic hose pump according claim 4 for
generating a fluid flow through a medical instrument 11, wherein a
fluid source is connected at a feeding side of the hose, wherein
the medical instrument is connected at a pressure side of the hose,
and wherein the roller wheel is driven with a preselected and
constant speed for feeding the fluid from the feeding side to the
pressure side.
14. The use of a peristaltic hose pump according claim 5 for
generating a fluid flow through a medical instrument 11, wherein a
fluid source is connected at a feeding side of the hose, wherein
the medical instrument is connected at a pressure side of the hose,
and wherein the roller wheel is driven with a preselected and
constant speed for feeding the fluid from the feeding side to the
pressure side.
15. The use of a peristaltic hose pump according claim 6 for
generating a fluid flow through a medical instrument 11, wherein a
fluid source is connected at a feeding side of the hose, wherein
the medical instrument is connected at a pressure side of the hose,
and wherein the roller wheel is driven with a preselected and
constant speed for feeding the fluid from the feeding side to the
pressure side.
16. The use of a peristaltic hose pump according to claim 11,
wherein the fluid source is a fluid container, which is arranged,
preferably by 0.1 to 2 m, most preferably 0.1 to 1 m, above the
higher end of the pump segment, the fluid container communicating
with the feeding side of the hose without interposed pump.
17. The use of a peristaltic hose pump according to claim 12,
wherein the fluid source is a fluid container, which is arranged,
preferably by 0.1 to 2 m, most preferably 0.1 to 1 m, above the
higher end of the pump segment, the fluid container communicating
with the feeding side of the hose without interposed pump.
18. The use of a peristaltic hose pump according to claim 13,
wherein the fluid source is a fluid container, which is arranged,
preferably by 0.1 to 2 m, most preferably 0.1 to 1 m, above the
higher end of the pump segment, the fluid container communicating
with the feeding side of the hose without interposed pump.
19. The use of a peristaltic hose pump according to claim 14,
wherein the fluid source is a fluid container, which is arranged,
preferably by 0.1 to 2 m, most preferably 0.1 to 1 m, above the
higher end of the pump segment, the fluid container communicating
with the feeding side of the hose without interposed pump.
20. The use of a peristaltic hose pump according to claim 15,
wherein the fluid source is a fluid container, which is arranged,
preferably by 0.1 to 2 m, most preferably 0.1 to 1 m, above the
higher end of the pump segment, the fluid container communicating
with the feeding side of the hose without interposed pump.
Description
FIELD OF THE INVENTION
[0001] The invention concerns a peristaltic hose pump, in
particular for use in the field of medicine, comprising a roller
wheel, which can be driven about a roller wheel axis, and which has
rollers that are mounted thereon, the roller wheel rotation axes of
which are arranged on a circle concentric with the roller wheel
axis, the rollers partly projecting beyond the roller wheel,
comprising a hose, which has a flexible and elastic pump segment,
the pump segment being fixable in the axial direction at its two
opposite ends by means of one fixing point each, and the pump
segment being guided around the roller wheel under elastic tension.
The invention further concerns the use of such a peristaltic hose
pump for generating a fluid flow through a medical instrument.
BACKGROUND OF THE INVENTION AND PRIOR ART
[0002] Peristaltic hose pumps of the construction mentioned above
are known in various variants. There are in principle two basic
concepts. The first basic concept is that the hose arranged around
the roller wheel is pressed by means of a pressure arched element
or the like against the roller wheel. Such embodiments are for
instance known from the documents U.S. Pat. No. 4,798,580 and U.S.
Pat. No. 5,044,902. The second basic concept, on which the
invention is based, consists in that the elastic hose is pulled by
a tensile force of suitable size with a sufficient angle of
wrapping, typically more than 90.degree. and less than 270.degree.,
in most cases in the range from 150.degree. to 220.degree., around
the roller wheel. Thereby, a pressure arched element or the like is
not necessary. The tensile force is dimensioned according to the
elastic properties of the hose such that in the region of a roller
of a roller wheel, the interior cross-section of the hose is
reduced to practically zero. By rotation of this region with the
roller about the roller wheel axis, the feed of the fluid in the
hose is effected. Examples are described in the documents U.S. Pat.
No. 4,537,561 and U.S. Pat. No. 5,213,483. A particularly
advantageous variant of the second basic concept is described in
the document DE 199 60 668 A1.
[0003] It is common to all above peristaltic hose pumps that across
a broad range there is a nearly linear correlation between the
speed of the roller wheel and the flow, and in fact independently
from the generated pressure respectively counter-pressure. In these
connections it is however also known that with very high pressures
respectively counter-pressures, typically above 530 mbar, the
correlation between speed and flow becomes non-linear.
[0004] When using peristaltic hose pumps in the field of medicine,
for instance for generating a flow through a body cavity by
introduction of a medical instrument, which is fed by means of the
peristaltic hose pump with fluid, the pressure respectively
counter-pressure is a critical parameter. A doctor wishes on the
one hand a high flow for rinsing the body cavity. On the other
hand, a certain pressure is in fact desirable for expanding the
body cavity, this pressure is however also a very critical
parameter. Approx. 500 mbar, better 400 mbar, should definitely not
be exceeded. Typical pressures, which are medically harmless, are
in the range from approx. 50 to 300 mbar.
[0005] For peristaltic hose pumps of prior art construction,
comprehensive safety measures are provided, in order to safely
prevent an inadmissible pressure rise in a body cavity when
adjusting a high flow. Typically, a pressure sensor is provided,
which regularly monitors the pressure in the body cavity and/or the
feed line to the medical instrument respectively the pressure side
of the peristaltic pump and adjusts the drive of the roller wheel
to smaller speeds, if the pressure is too high. It is even possible
that the roller wheel is adjusted to reverse operation in the case
of a strong pressure rise in the body cavity. This will in
particular take place, when an inadmissibly high pressure could
occur at a very small flow already.
[0006] The above measurement and control measures are all in all
expensive, thus prior art peristaltic hose pumps being costly. It
would be desirable to provide a peristaltic hose pump for use in
the field of medicine, the roller wheel speed of which is
preselectable and otherwise constant, and in which a defined limit
pressure cannot be exceeded for any of the preselectable speeds,
and in fact without the necessity of suitable pressure sensors and
control of the speed of the roller wheel.
TECHNICAL OBJECT OF THE INVENTION
[0007] It is therefore the technical object of the invention to
propose a peristaltic hose pump, which can be obtained in a simple
construction, in particular does not need measurements of the
pressure in the body cavity respectively on the pressure side of
the peristaltic pump, nor control measures for the drive of the
roller wheel, and which nevertheless safely excludes that a given
maximum limit pressure is exceeded.
SUMMARY OF THE INVENTION AND PREFERRED EMBODIMENTS
[0008] For achieving this technical object, the invention teaches a
peristaltic hose pump comprising a roller wheel, which can be
driven about a roller wheel axis, and which has rollers that are
mounted thereon, the roller wheel rotation axes of which are
arranged on a circle concentric with the roller wheel axis, the
rollers partly projecting beyond the roller wheel, comprising a
hose, which has a flexible and elastic pump segment, the pump
segment being fixable in the axial direction at its two opposite
ends by means of one fixing point each, and the pump segment being
guided around the roller wheel under elastic tension, wherein the
length of the pump segment when not under tension in proportion to
the distance of the fixing points to the roller wheel rotation axis
is adjusted with the provision that while the roller wheel is
stationary and when applying a fluid pressure in the range from 10
to 400 mbar to one end of the pump segment, a flow of the fluid of
at least 0.01 1/min through the pump segment is obtained.
[0009] The roller wheel is typically set into rotation by means of
an electric motor drive, thereby the cross-section of the pump
segment of the hose being reduced in the region of a roller. The
speed of the roller wheel may be unregulated, for instance by
applying a preselectable voltage (for analogous electric motors) or
frequency (for stepper motors) to the electric motor drive. It is
also possible to keep the speed of the roller wheel constant at a
preselectable speed by a control loop. Then, a transducer, for
instance a speedo dial, is typically arranged on the shaft of the
roller wheel, by means of which a speed signal is generated. This
speed signal is then compared in an analog or digital comparator
with a preselected nominal signal. When the speed signal indicates
a too low speed, compared with the nominal speed correlated with
the nominal signal, the comparator increases the voltage
respectively the frequency, which is applied to the electric motor
drive. An essential element of the invention is that this control
or regulation does not obtain nor need as input signal a signal of
a pressure sensor arranged on the pressure side of the peristaltic
hose pump.
[0010] A pump segment of a hose is a partial length of the hose,
which is made of an elastic and flexible material. At the ends of
the pump segment respectively follow partial lengths of the hose,
which in most cases, but not necessarily are made of another
material and/or are differently dimensioned. The partial length of
the hose, which forms the pump segment, is limited and defined by
the fixing points. The fixing points are disposed in the geometric
layout, related to directions orthogonal to the roller wheel axis,
at defined and fixed points in the peristaltic pump. Thereby, the
hose segment of a certain length is, after guiding it around the
roller wheel, under an elastic tension given according to the
length.
[0011] The invention is based first of all on the finding that the
reason for the non-linearity between speed and flow at high
pressures is that with very high pressures, the interior
cross-section of the hose respectively of the pump segment is
reduced not to zero anymore in the region of a roller of the roller
wheel because of the (counter-) pressure. Because of the pressure,
there is therefore a backflow, referred to the reduced interior
cross-section of the pump segment and the revolution thereof about
the roller wheel axis, in opposition to the direction of rotation
of the roller wheel and consequently the feed direction of the
peristaltic hose pump. This backflow in turn is a function of the
pressure and becomes the higher, the higher the pressure on the
pressure side of the hose pump is.
[0012] The invention makes use of this finding for adjusting a
maximum attainable pressure in medically compatible pressure
ranges, i.e., below 400 mbar, preferably below 300 mbar, by
allowing the provision of a backflow at normal operating conditions
already. By the fact that even while the roller wheel is
stationary, a flow is already made possible, so to speak a defined
back flow leakage in the region of the reduced interior
cross-section of the pump segment in the region of a roller is
provided. This back flow leakage acts quasi as a bypass valve from
the pressure side to the feeding side of the hose.
[0013] By a peristaltic hose pump according to the invention, it is
achieved that with simplest design, namely without
pressure-controlled regulation of the roller wheel drive and
without pressure measurement and indication, nevertheless a hose
pump for medical purposes meeting all safety requirements is
obtained. A peristaltic hose pump according to the invention can
thus be produced very cost-effectively. Further, its handling is
extremely simple, since an operator only needs to select a defined
speed, at which the roller wheel then constantly turns until
another preselection. Even with maximum preselected speed,
exceedance of a defined maximum admissible pressure value is
inherently excluded.
[0014] Essential for the invention is the set-up of the length of
the elastic pump segment when not under tension in proportion to
the distance of the fixing points to the roller wheel rotation
axis. In other words, the set-up comprises the proportion of the
length of the pump segment when not under tension to the length of
the pump segment when the pump segment is guided under tension
around the roller wheel by means of the fixing points.
[0015] The set-up can in principle be provided in two different
ways. On the one hand it is possible to vary the length of the pump
segment when not under tension with fixing points being invariable
with respect to the roller wheel axis. By a test series with
different lengths of the pump segment when not under tension it can
be tested, whether the flow according to the invention is provided
when the pump segment is guided under tension around the roller
wheel and while the roller wheel is stationary. Alternatively, with
invariant length of the pump segment, the distance of a fixing
point or the distances of both fixing points with respect to the
roller wheel rotation axis can be varied and adjusted in a test
series so that the flow according to the invention when the pump
segment is guided under tension around the roller wheel and while
the roller wheel is stationary. Depending on the employed hose
material for the pump segment and its dimensions, the provision
according to the invention can easily be adjusted by tests and
assignment to the respective constructional design of the pump
segment.
[0016] In a peristaltic hose pump according to the invention,
usually the distance of the fixing points to the roller wheel
rotation axis will not be adjustable. Rather, regularly the length
of the pump segment when not under tension is adapted thereto in
the above manner. For test purposes respectively for the test
series mentioned above of the second alternative, it is however
also possible that a peristaltic hose pump is designed such that
the distance of at least one fixing point to the roller wheel
rotation axis is adjustable.
[0017] For the purpose of a peristaltic hose pump according to the
invention, other hoses can also be used. With unchanged distance of
the fixing points to the roller wheel rotation axis, the length of
the hose segment has been determined and adapted in a corresponding
way for every type of a hose respectively hose segment. This may in
particular have been made for instance with a hose cassette
according to the document DE 199 60 668 A1, to which herewith
reference comprehensively is made.
[0018] Preferably, it is provided that while the roller wheel is
stationary and when applying a fluid pressure in the range from 10
to 300 mbar, preferably from 10 to 200 mbar to one end of the pump
hose segment, a flow of the fluid from 0.01 1/min to 1 1/min,
preferably to 0.5 1/min, most preferably to 0.1 1/min is
obtained.
[0019] Alternatively respectively preferably, the set-up of the
length of the pump segment when not under tension in proportion to
the distance of the fixing points to the roller wheel axis is made
with the provision that with maximum speed of the roller wheel and
closed pressure side of the hose, a pressure of not more than 500
mbar, preferably of not more than 450 mbar, most preferably not
more than 400 mbar, in particular not more than 350 mbar or 300
mbar, appears on the pressure side. In addition to this, an
optimization of the flow can also simultaneously be made such that
with the above maximum pressures a maximum flow, for instance of
more than 0.6 1/min, preferably more than 0.7 1/min, most
preferably more than 0.8 1/min, in particular more than 0.9 1/min,
for instance more than 1.0 1/min, is achieved.
[0020] As an additional safety measure against inadmissibly high
pressures, a bypass line with a pressure-controlled bypass valve
can be arranged between the regions of the ends of the pump
segment. The bypass valve can open at a pressure from 100 to 500
mbar, preferably 200 to 400 mbar, most preferably 300 to 350 mbar.
The clear cross-section of the bypass line with opened bypass valve
can be 10 to 100%, preferably 20 to 50%, of the clear cross-section
of the pump segment when not under tension. The clear cross-section
is the total passage area for the fluid.
[0021] Typically the following materials can be used for the pump
segment: elastomeric silicone polymers, soft PVC or similar
materials, which are known to the man skilled in the art. Typical
inner diameters are in the range from 6 to 10 mm, preferably 7 to 9
mm, for instance 8 mm. Typical wall thicknesses are in the range
from 1 to 2 mm, for instance 1.5 mm.
[0022] The invention also concerns the use of a peristaltic hose
pump according to the invention for generating a fluid flow through
a medical instrument, wherein a fluid source is connected at a
feeding side of the hose, wherein the medical instrument is
connected at a pressure side of the hose and wherein the roller
wheel is driven with a preselected and constant speed for feeding
the fluid from the feeding side to the pressure side. For the
preselection, typically a rotary switch or a key pad can be
provided, and to each switch position respectively each key, a
defined constant speed of the roller wheel is assigned, and the
electric motor drive of which is correspondingly controlled.
Instead of a rotary switch, a continuous control element, such as
for instance a potentiometer, can also be provided. Of course, a
digital entry respectively preselection of the speed by means of an
input field is also possible.
[0023] Preferably, the fluid source is a fluid container, which is
arranged, preferably by 0.1 to 2 m, most preferably 0.1 to 1 m,
above the higher end of the pump segment, the fluid container
communicating with the feeding side of the hose without interposed
pump. The hose pump acts quasi as a booster for the hydrostatic
pressure resulting from the arrangement of the fluid container.
Compared to the classic bag suspension and height adjustment
without pump, an increased flow through the medical instrument
achieved being often medically desirable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] In the following, the invention is explained in more detail
with reference to figures representing an example of execution
only. There are:
[0025] FIG. 1: a schematic view of a peristaltic hose pump
according to the invention, and
[0026] FIG. 2: the arrangement when using a peristaltic hose pump
according to the invention in the field of medicine.
DETAILED DESCRIPTION
[0027] In FIG. 1 it can first be seen that the peristaltic hose
pump comprises a roller wheel 1 which can be driven about a roller
wheel axis D, said roller wheel 1 having rollers 2 that are mounted
thereon, the roller wheel rotation axes of which R being arranged
on a circle concentric with the roller wheel axis D, the rollers 2
partly projecting beyond the roller wheel 1. The roller wheel axis
D and the roller wheel rotation axes R extend in parallel to each
other. For reasons of clarity, the electric motor drive of the
roller wheel is not shown, which is supplied with preselectable
operating voltages. For this purpose, suitable power supply
circuits are provided.
[0028] Furthermore, a hose 3 is provided, which has a flexible and
elastic pump segment 4, in the embodiment made of an elastomeric
silicone polymer. The pump segment 4 is fixed at its two opposite
ends 5, 6 in the axial direction, referred to the pump segment, by
means of one fixing point P1, P2 each. The fixing points P1, P2 can
allow a rotation of the end of the pump segment 4 about an axis
orthogonal to the axial direction of the pump segment 4.
[0029] In the representation of FIG. 1, the pump segment 4 is shown
in mounted condition, i.e. guided under elastic tension around the
roller wheel 1 and when under tension. When under tension, the pump
segment 4 has the length L2. When not under tension, i.e. not
guided around the roller wheel 1, the pump segment 4 has a length
L1 (not shown). The length L1 is smaller than the length L2. The
length is herein the longitudinal extension of the center axis
through the pump segment 4.
[0030] The length L1 of the pump segment 4 when not under tension
is adjusted in proportion to the distance A of the fixing points
P1, P2 to the roller wheel axis D respectively to the length L2
with the provision that while the roller wheel 1 is stationary and
when applying a fluid pressure in the range of 100 mbar to one end
P1, P2 of the pump segment 4, a flow of the fluid of approx. 0.3
1/min through the pump segment 4 is obtained.
[0031] For adjusting the above provision respectively for
carrying-out test series for determining the suitable length L2,
the distance A of one or both fixing points P1, P2 to the roller
wheel rotation axis D can be adjustable. Usually, however, the
distance A will not be adjustable, and the length L1 of the pump
segment 4 has been adapted correspondingly in previous tests.
[0032] Furthermore, it can be seen in FIG. 1 that a bypass line 7
with a pressure-controlled bypass valve 8 is arranged between the
regions of the ends 5, 6 of the pump segment 4. The bypass valve 8
opens at a pressure of approx. 300 mbar. By means of the bypass
line 8 and the bypass valve 8, if applicable an additional backflow
for the pressure relief of the pressure side 10 is provided. The
bypass valve 8 may be carried out in most various ways. In the
simplest case, it is a pressure-dependant mechanical control
element, having a valve seat and a spring-loaded closing element
that without any further control from outside opens against the
spring force or closes with the spring force. By pressure
application to the closing element, the latter will be moved
against the spring force, when a predetermined maximum pressure
value defined by the spring force is exceeded, and will come free
from valve seat, so that fluid can drain respectively flow back
from the pressure side through the bypass valve 8. Alternatively,
the bypass line 7 may be a flexible hose, which extends in a
clamping element. Such a clamping element comprises a supporting
surface, against which the bypass line 7 rests, and a clamping
actuator, which for instance can be driven by an electric motor,
and which is pressed on the bypass line 7 on the side of the bypass
line 7 opposite to the supporting surface and compresses the bypass
line 7 against the supporting surface. Thereby, a continuous
variation of the flow cross-section through the bypass line 7 and
thus a continuous variation of the pressure can be obtained.
[0033] In FIG. 2, the use of the peristaltic hose pump according to
the invention for generating a fluid flow through a medical
instrument 11 is shown. At the feeding side 9 of the hose 3, a
fluid source 12 is connected. At the pressure side 10 of the hose
3, the medical instrument 11 is connected, the end of which can for
instance be introduced into a not shown body cavity. The roller
wheel 1 is driven with a preselected and constant speed for feeding
the fluid from the feeding side 9 to the pressure side 10. For
preselecting the desired constant speed, a rotary switch 13 is
provided. Of course, instead of a rotary switch 13, a continuously
operating actuator can also be provided. In FIG. 2 it can further
be seen that the fluid source is a fluid container 12, which is
arranged approx. 1 m above the end 6 of the pump segment 4. Between
the fluid container 12 and the feeding side 9 of the hose 3, there
is no pump or the like interposed.
[0034] In particular in FIG. 2 can be seen that a peristaltic hose
pump according to the invention basically effects an increase of
the hydrostatic pressure provided by the fluid container 12.
[0035] In the following, a test series for determining a suitable
length L2 is described. For this purpose, a peristaltic hose pump
of the basic design of FIG. 1 was used. By a manually operated
spindle drive, the distance A of the two fixing points P1, P2 could
be varied. A change of the distance A therefore corresponds to a
change of the length L2 by twice the change of the distance A.
Besides that, it is a standard hose pump and a standard pump
segment 4.
[0036] The measurements were made with a structure according to
FIG. 2 by means of a standard instrument as medical instrument,
which was introduced into a dummy representing a body cavity. The
dummy comprised an outflow cock. First, the flow with opened
outflow cock was measured. Then the outflow cock was closed, and
the resulting pressure in the dummy was measured. The fluid
container was arranged at a level of approx. 1 m above the fixing
point P1. The dummy was approx. at the level of the fixing point
P1. The data in Table 1 were obtained.
[0037] The parameter A is given in arbitrary relative units. Speed
is the speed of the roller wheel. Graviflow designates the flow
while the roller wheel is stationary. Flow indicates the maximum
flow with opened outflow cock. Pressure in the dummy indicates the
maximum pressure in the dummy with closed outflow cock. The values
in parentheses are measured values that were taken again after 2
hours elapsed.
TABLE-US-00001 TABLE 1 Pressure in A Speed Graviflow Flow the dummy
[mm] [UpM} (l/min] [l/min] [mbar] -2 50 0.46 0.35 (0.40) 104 (103)
-2 100 0.46 0.50 (0.50) 108 (117) -2 150 0.46 0.50 (0.50) 120 (138)
-2 200 0.46 0.55 (0.55) 133 (159) -2 300 0.46 0.60 (0.70) 172 (212)
0 50 0.33 0.40 (0.35) 130 (139) 0 100 0.33 0.50 (0.50) 178 (208) 0
150 0.33 0.55 (0.60) 234 (258) 0 200 0.33 0.70 (0.75) 280 (305) 0
300 0.33 0.90 (1.00) 371 (391) 2 50 0.22 0.30 (0.25) 172 (212) 2
100 0.22 0.50 (0.55) 308 (323) 2 150 0.22 0.70 (0.75) 401 (397) 2
200 0.22 0.80 (0.85) 482 (461) 2 300 0.22 1.20 (1.20) 580 (559) 4
50 0 0.25 (0.25) 270 (322) 4 100 0 0.50 (0.55) 462 (450) 4 150 0
0.75 (0.75) 558 (551) 4 200 0 1.00 (1.00) 662 (620) 4 300 0 1.40
(1.35) 772 (738) 6 50 0 0.25 (0.25) 270 (404) 6 100 0 0.50 (0.55)
596 (584) 6 150 0 0.75 (0.75) 743 (712) 6 200 0 1.05 800
[0038] It ca be seen that for A=-2, 0 and 2, the roller wheel 1
does not seal the pump segment 4. For A=-2, the attainable flow is
relatively low. For A=0, the attainable flow is satisfactory. For
A=-2 and 0, there are no maximum pressures of more than 400 mbar.
The optimum adjustment is therefore A=0.
* * * * *