Note: Descriptions are shown in the official language in which they were submitted.
7 $
~091/19099 PCT/SE91/00411
-- 1
Ape~ratus for repetit lv dispensing a measuredvolume of li~uid.
This inve1~tion relates to apparatus for repetitively
dispensing av measured volume of liquid and more particularly
relates to a dispensing apparatus comprising a dosing piston
pump having a dosing pump cylinder and a dosing pump piston
which is reciprocable in the dosing pump cylinder and defines
together with the dosing pump cylinder a dosing pump chamber
having an outlet for the discharge of measured volumes of
liquid, and a cylically operating actuating mechanism for
positively driving the dosing pump piston at least in the
direction corresponding to contraction of the dosing pump
chamber.
Dispensing apparatus of khis kind have many different
applications, and as an illustrative example packaging
machines for filliny packages with measured volumes or por-
tions of liquid can be taken. The apparatus according to this
invention is useful in such packaging machines and accordingly
will be described with particular reference to its use as a
filling apparatus in a pacXaging machine. However, the in-
vention is not limited to this application, which is only tobe taken as an illustrative example.
Packaging machines for liquid, such as for liquid food-
stuffs, e.g., milk or the like, are often required to dispense
at high rates an accurately measured volume of liquid while
meeting stringent hygienic requirements. In such applications,
the volume of the liquid portion to be dispensed to each
package and, conse~uently, the stroke volume of the dosinq
piston pump, may be quite large.
A rapid dispensinq rate coupled with a large ~olume of the
portions means that the dosing piston pump and the conduit
system associated with it have to cope with a large ~olumetric
flow rate. Because of the intermittent and rapid discharge of
the liquid from the dosing piston pump, the liquid has to be
accelerated and retarded quickly every time a discharge takes
place.
The stringent requiremen~s on hygiene which have to be met
i~ many cases, such as in machines for packaging liquid food-
;
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~9l/i9099 PCr/SE91/00411
stuffs, also means a complication. The need to cleanse the
surfaces in the dispensing system which are contacted by the
product makes it neccessary when designing the dispe~sing
system to take into account the requirements related to the
cleansing, and in any case the cleansing requires a substan~
tial effort.
An ob~ect of the invention is to provide dispensing appa-
ratus of the kind indicated above and, more particularly, to
provide
~ a dispensing apparatus to which the liquid to be dis-
pensed can be supplied substantially continuously, although
the liquid is discharged discontinuously;
- a dispensing apparatus which can operate at a hi~h rate
and with a large portion volume without requiring rapid acce-
leration and retardation of large ma~ses of liquid for each
dispensing cycle;
- a dispensing apparatus which can operate at a high rate
while keeping the volume of liquid di~pensed in each cycle of
operation wi$hin clo~e tolerances;
- a dispensing apparatus in which the surfaces contacted
by the liquid are provided in a readily and quickly replace-
able, pr~ferably sterilisable unit which, if required, can be
made sufficiently inexpensive to lend it~elf, partially or
completely, to one-way use, 60 that it will be economically
feasibla to discard the entire unit, or parts thereof, and
substitute it ~or a new ~ne in ~ituations in which cl~ansing
of the surfaces would otherwi~e ~e neccessary, and ~o that the
packaging machine need not be shut down for cle~nsing o~ the
dispen~ing apparatus~
- a dispen~ing apparatus in which the passages through
which the liquid flows to the dosing piston pump can be made
with a large cross-sectional flow area and a ~hort length so
that the the filling of the dosing pump chamber can take place
rapidly and at low 105s of pre~ure, that is, at low losses of
energy;
- a di~pen~ing apparatu~ in which en~rgy of the continu-
ously inflow~ng liquid ca~ be stored during the phase of the
~91/19099 PCT/SEl91/OOq11
cycle of operation in which the in~low passage o~ the dosing
piston pump is blocked, that is, during the dispensing phase,
and then utilized to oontribute to the filling of the dosing
piston pump when the inflow passage thereof i~ again opened;
- a-dispensing device w~ich is capable of operating at an
arbitrary and varying filling pre~sure, e.g. between 0.5 and
2.5 bars, and al80 capable of meeting heavy demands in respect
of rate of operation, portion volume, ~nd accuracy of the
dispensed ~olu~e;
- a dispensing apparatus which can be made ~ompact ~ut yet
provides ready access to its components for service and main-
tenance.
A dispensing apparatus which meets the above and su~h
other requirements as are often applied to dispensing appara-
tus of the kind contemplated here is shown diagrammatically
and by way of a non~limiting example in the accompanying
drawings and is described in more detail below with reference
to the drawi~gs.
Fig. 1 i~ a diagrammatic vertical sectional view of the
dispen~ing apparatus;
Fig~ 2 is a top plan Vi2W of a replaceable unit which is
psrtially or wholly adapted for one-way use and forms part of
the dispensinq apparatus of Fig. l, the unit being shown in
its shipping configuration;
Fig. 3 shows a section of the unit of Fig. 2 along line
II -II with an inlet tube and and inlet tube forming parts of
the unit ~wung out to an operating position.
The dispensing apparatus ~hown by way of example comprises
an inlet tube generally designated by ll through which ~he
liquid, such as milk or some other liquid ~ood product, is fed
to the di~pensing apparatus, a feed piston pump generally
designated by 12, which i8 in con~tant open communication with
the inlet tube, a ~o~ing pi~ton pu~p generally designated by
13, which i~ in fluid flow communication with t11e feed piston
pump l2, a valve generally designatQd by 14, which controls
the fluid flow communication between the pump6 12 and l~, and
an outlet tube, generally designated by 15, through which the
2 ~ 7 3
. 9l/1~099 PCT/SE91/004~1
,g
metered volumes or portions of liquid are discharged in
succession to packages, ~or example.
The inlet tube 11 is in constantly open communication with
the pump chamber 17 of the feed piston pump 12, the communica-
tion ~xhibiting a very low flow resistance. The piston 18 ofthe pump is movable vertically in a cylinder provided in a
pump housing which is common to the two pumps 12 and 13. A
driving motor 21, which is shown only as a sym~ol, drives ~he
piston 18 in the cylinder and to this end is connected with
the pi6ton through a ball bearing 6crew-and-nut mechanism 22.
The piston movement is positive at least in the upward direc-
tion, i.e. in the direction in which the piston moves to
contract the pump chamber 17. A shock absorbing member 23
provided on the piston absorbs any pressure shocks occurring
in the pump chamber 17~
The dosing piston pump 13 is disposed sid~ by side with,
and 6uitably immediately adjacent to, the feed pi~ton pump 12.
Its piston 26 is movable vertically in a cylinder 27 which is
formed in the pump housing 20 and parallel to the cylinder 19.
A driving ~otor 28 drive~ the pi~ton in the cylind~r 27
through a ball bearing screw-and-nut mechanism 29. The mov~-
ment of the piston 26 of the dosing pi~ton pump 13 i5 also
positive at least in the upward direction, i.e. the direction
which corresponds to contraction of the pump chamber 30.
A horizontal transf~r passage 31 provides for the above-
mentioned fluid flow communication between the pump chamber 17
of the feed piston pump 12 and the pump chamber 30 of the
dosing piston pump 13. This passage is provided at the upper
end of the pump cylinders 19 and 27 and formed by removing
across the width or diameter of the pump chambers the upper-
most portion of the pump housiny partition 32 separating the
pump chambers 17 a~d 30. Accordingly, the trans~er passaqe 31
has a width, as ~easured horizontally and perpendicularly to
the plane of Fig. 1~ which is at least as large as the dia-
meter of the pump chamber~ 17 and 30. As measured v~rtically,the dimQnsion o~ the transfer pa~sage is ~ub~tantially
smaller, but because of the large width of the passage, its
r/s~1 /oo4l 1
cross-Rection ~low area nevertheless is very l~rge, for
example, 15 to 4Q % of the cross-section area of the piston 18
of the feed piston pump 12. As measured horizontally and
parallel to the plane of Fig. 1, the length of the transfer
passage varies from a minimum at the v~rtical plane (the plane
of Fig. 1) which contains the parallel axes of the two pumps
to a maximum on either slde of this plane and at ~ome distance
~rom the plane.
The valve 14l which control~ the transfer of the liquid
through the pa~sage 31 ~rom the feed pi6ton pump 12 to the
dosing piston pump 13, includes a valve member 35 in the shape
of a circular cylindrical sleeve which surrounds the pump
piston 26 concentrically and i6 axially displaceable b~tween a
closed posi~,ion and an open position by means of a two-posi-
tion valve actuating device comprising three solenoids 36.These solenoids are uniformly spaced circumferentially about
the pump pi~ton 26 and act on the lower edge of the valve
member 35 through the intermediary of respective push rods 37.
In the closed po~ition, the upper ~dge of the valve member
35 sealingly engage~ the underside of a top pump housing part
40 which ~orms the pump housing 20 together with a bottom pump
hou~ing part 41. In the open position the upper edge of the
valve ~ember 35 is flush with or positioned slightly below the
upper side of the partition 32 ~eparating the pump chambers,
so that the tran~fer passage 31 is then ~pen throughout the
cross-section flow area.
A thin, very ~lex~ble membrane 42, such as a film of
polyurethane, prov~deæ a ~eal b~tween the two pump pi~tons 18
and 26, on the one hand, and the cylinders 19 and 27, on th~
other hand. Throughout its outer edge the m~mbrane 42 i~
sealingly clamped between a top Bection 40A and a bottom
section 40B of the top pump housing part 40, and it overlies
th~ upper edge of the ~alve ~mber 35, the upper side of the
partition 32 and the upper ~id~ of the two pump piston~ ~8
and 26. The upper 6idQ o~ each o~ tbe pump pi~ton~ 18 and 26
is ~ormed by an inverted cup-shaped piston c~p 18A and 26A,
, . .. .
~_91~19099 PCr/SE~1/00~1
-- 6 --
respectively, which is loos~ly positioned over a piston head
18B, 2SB~
In the gap between the pump housing 20 and the piston 18
of the feed piston pump 12, in the gap between the pump hous-
ing 20 and the valve member 35, and in the gap bet~een ~hevalve member 35 and the piston 26 of the dosing piston pump
13, the membrane 42 hang~ down to form a rolling membrane
which seals between the elements which move relative to one
another.
The compartments 45 and 46 between the bottom pump housing
part 41 and the underside of the pu~p pistons 18 and 26,
respectively, are sealed with respect to the ~urrsunding
space. Through flexible co~duits 47 and 48 they are connected
to a pneumatic pressure control device 49 by means of which
lS the compartments can be subjected to a controlled reduced or
elevated pressure at predetermined points in the operating
cycles of the pumps.
Upwardly, the pump chambers 17 and 32 are defined by the
top section 40A of the top pump hou~ing part 40. The portion
of the top section 40A which i~ situat~d abov~ the pump cham-
ber 17 is provided with a connector 52 ~or the inlet tube ll.
Correspondingly, the portion 9~ the top section 40A which is
situated above the pump chamber 30 is provided with a connec-
tor 53 for the outlet tube 15.
~5 In the outlet tube 15, nam~ly, in the inlet por~ion there-
of, which cooperakes with the connector 53 and is open towards
the pump chamber 30, there ~6 provided a valve seat 55 which
faces away from the pump chamber. A membrane 56 attached to
the connector 53 can be pressed against this valve seat by
means of an associated valve member 57 to close off the outlet
tube 15. A relatively weak compres~ion spring 58 constantly
urges the valve member 57 towards the closed position. How-
ever, the closing force on the valve member 57 can be in-
crea~ead substantially by means ~f a solenoid 59.
A control unit 60 a~so~iated with the di~pensinq apparatus
control~ the pump motors 21 and z8 to cause them to move at a
selected frequency and with a selected time-travel charac-
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J 91/19099 PC'r/SE~1/01:3~111
- 7
teristic. The control unit 60 continuou~ly sense~ the position
of the pump pistons 18 and 26 by means of motion transducers
(not shown) which are conn~cted to the pump pistons. The
control unit 60 al50 controls the solenoids 36 for the valve
member 35 in the transfer passaye 31, the solenoid 59 for the
outlet valve member 57, and the pressure control devîce 49~
Accordingly, the operating cycl~ of the dispensing apparatus
is controll~d by the control unit 60, which also includes a
selector for ~etting the dosage or portion volume, weight
transducers for measuring the weight of the dispensed por-
tions, etc.
A pump or operating cycle of the illustrated di~pensin~
apparatu~ passes off as follows.
The entire flow path for the liquid which the dispensing
device transports ~nd dispenses - this path, which extends
through the dispensing apparatus, includes the inlet tube 11,
the pu~p chamber 17 of the feed piston pump 12, the transfer
passage 31, the pump cha~ber 30 of the dosing piston pump 13
and finally the outlet tube 15 - is assum~d to be filled wi~h
liquid, and it is also as~umed that the pump has just comple-
ted dispensing a liquid portion through the outlet tube 15.
In the thus assumed initial or tarting position, the
valYe member 57 in the outlet tube 15 has just closed against
the valve seat 55 under the action o~ the ~pring 58 a~er the
piston 26 of the dosing piston pump has reached its uppermost
position. The annular cylindrical valve ~ember 35, namely the
upper edge thereof, sealingly engage~ the top section 40A of
the top pump hou~ing part 40 through the intermediary o the
intervening membrane 42 and thereby block~ the transfer
passage 31 to prevent flow between the pump chamber~ 17 and
30.
The operating cycle described below is commenced by ener-
gizing the solenoid 59 to ensure that the valve member 57 is
retained in the closed po~ition even when it i~ ~ubje~ted to
the pres~ure exi~ting in the inl2t tub~. Thereupon th~ valve
member 35 is displaced downwardly to open the tr~nsi~er paææage
31. This movement of the valve member is brought about by the
.
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~ J
,91/190~9 I'Cr/SE91/00411
pressure exerted by the liquid on the portion of the membrane
42 which is supported by the valve member. Simultaneously or
almost simultaneously, the piston 26 of the dosing pi6ton pump
13 starts moving downwardly to permit filling of th~ pump
chamber 30. The downward movement of the piston 26 can be
brought about by the driving motor 2B, or at least controlled
by this motor, through signals from the control unit 60.
As soon as the valve member 35 has opened, the liquid can
flow into the pump chamber 30 without undergoing any-appreci~
abla pressure drop; the pres~ure drop is negligible be~ause o~
the small length and the large width of th~ passaqe. Conse-
quently, the pump chamber 30 can be filled extremely rapidly.
If the liquid supplied to the the di pensing apparatus is
under a certain overpressure, as it normally is, the pressure
tends to drive the pi~ton 26 downwardly, and the driving motor
28 then actually has to operate as a brake (generator). If
required, the downward force on the piston can be counteracted
by an sverpxessure in the comp~rtment 46 beneath the piston so
that the load on the motor is reduced. Such an overpressure
also can contribute to preventing overloading of the membrane
42 at the folds or rolling membrane portions which hang down
between the piston 26 and the ~urrounding valve member 35 and
betwaen the latter and the cylinder 27.
Simultaneously with, or shortly after, the opening of the
valve member 31 and the commencement of the downward movement
of the piston 26 in the dosing pi~ton pump 13, the driving
motor 21 of the ~eed piston pump 12 starts driving the pîston
18 of the feed piston pump upwardly. The piston 18 thereby
displaces the li~uid already contained in the pump chamber 17,
and at the ~ame time liquid can ~low more or 1eS8 direct from
the inlet tube 11 into the pump chamber 30 of the dosing
piston pump.
During the movement of the pistons 18 and 26, the pre~sure
in the compartments 45 and 46 beneath the pistons is con-
trolled by the control d~vice 49 such that an appropriatepressure differential i~ maintained between the pump chamber6
17 and 30, on the one hand, and the compartments 45 and 46 on
.. . .
' ~,'' ' ' ., ' :
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391/19099 PCI'/SE91/00411
the other hand. Thi~ pressure differential should ensure that
the cylindrical folds of the membrane 42 which form rolling
membranes remain tightened and perform a uniform rolling
motion without becoming excessively loaded.
While the filling of the pump chamber 30 of the dosing
piston pump goes on, the solenoid 59 in cooperation with the
relatiYely weak spring 58 acts to.keep the valve member 57 in
the outlet tube 15 in the clo~ed position agains~ ~he action
of the pressure of the liquid ~lowing into the pump chamber 30
so that no liquid ca~ flow out of the pump chamber.
When the pump chamber 30 has been filled, the pis~on 26 is
stopped and the valve member 35 i~ di~placed upwardly to the
clo6ed position by the ~olen~ids 36. ~acause the annular
cylindrical valve member, the wall of which may be very thin
in relation to its diameter, is acted on ~ymmetrically in the
radial directisn (horizontally~ and is loaded vertically
downwardly only over a small annular surface, no great force
is required to disp~ace the valve me~ber to the clo~ed po~i-
tion. Moreover, the volume of liquid which the valve member 35
displaces as a con~equence of its movement i~ very small.
The la~t-mentioned volume can be largely or completely
accommodated by the pump chamber 30 if the final phase o~ the
downward movement of the pump piston 26 is suitably matched
with the upward displacement of the valve member 35 to the
closed position. Consequently, the displacement of the valve
member to the closed posit~on can take place without causing
any backflow of liquid to the pump chamber 17 of the feed
piston pump.
After the valve member 35 has reached the closed position,
the dxiving motor 28 of the dosing piston pump 13 displace~
the piston 26 upwardly ov~r a distance which corresponds to
the v~lume to be dispensed for each pump operating cycle.
While the liquid i5 being di~pensed, the ~olenoid S9 is de-
energized so that the liquid can b2 di~pensed rapidly without
the valve member 57 causing any ~ubstantial pre~ure drop. I
requirea~ the pre~sure differential between the pump chamber
30 and the compartment 46 beneath the piston 26 can be in-
'` ' ' :
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3 i~
~.~9l/19099 PCT/SE9ltU041l
-- 10 --
creased during the final phase of the upward movement of thepiston, so that "overshooting" movement of the piston caused
- by the dynamic forces is counteracted.
During the phase of the operating cycle which follows the
closing of the transfer passage 31, the liquid continues to
flow into the pump chamb~r 17 of the ~eed piston pump 12. This
is possible bec~use the upward movement of the piston 18 of
the feed piston pump 12 is interrupted and the piston is
allowed to move downwardly so that the pump chamber 17 can
expand and accommodate the inflowing liquid. The downward
movement, which is brought about, or at lea~t controlled, by
the driving motor 22 on co~mand from the control unit 60,
suitably is initiated simultaneously withr or shartly before,
the upward displacement of the valve member 31 to the closed
position (in practice, the overpressure of the inflowin~
liquid causes the motor 22 as well to act as a brake or gene-
rator during the downward pi~ton movement).
When the piston 18 reaches its predetermined lowermost
position, the operating cycle is completed, and the chain of
events de~cribed above may be repeated.
If the reversal of the direction of movement of the piston
18 is suitably matched with the upward displacement of the
valve member 35 to the closed po~ition, the shock absorbing
member 23 on the piston 18 prevents the di~placement of the
valve member from causing pressure shocks in the inlet tube
and the supply conduit connected therewith, or at least can
provide an efficient damping of such pressure shocks.
As is apparent from the foregoing, the liquid to be dis-
pensed can flow continuously to the dispensing apparatus
without being substantially affected in the inl~t tube or the
~upply conduit by the cyclically operating dispensing appa-
xatus.. Because the liquid fIow from the inlet tube 11 into the
pump chamber ~0 of the do~ing piston pump 13 i~ virtually free
of pressure drop, the di~pensing apparatus i~ also very in-
3s sensitive to var~ing pressure of the flow of liquid suppliedto the dispensing apparatus.-As long as the rate of inflow to
the dispensing apparatus is sufficiently lar~e, the dispensing
.
09l/19099 PCr/SE91/0041l
apparatus is thus readily zapable of dispensing liquid por-
tions of the predetermined volume at the predetermined rate~
even if the pressure on the upstream side of the dispensing
apparatus varies in operation of the dispensing apparatus or
is different from the intended pressure.
The function of the feed piston pump as a "compliance
chamber", that is, a chamber which expands and s~ores liquid
that continues to flow into the dispensing apparatus during
thae phase of the operating cy~le in which transfer through
the transfer pas~age 30 is not possible, and i8 then con-
tracted when sUch transfer becomes po~sible, ne~d not necessa~
rily be fulfilled by a positively driven piston pump as in the
illustrated embodiment.
This function can also be fulfilled by an arrangement
whereby the space which in the illustrated embodiment is
formed by the pump chamber 17 is expanded under the action of
the pre~sure of the inflowing liquid ~gainst the action of a
spring bias o~ a displaceable wall of the c~amber, the con-
traction of the space then taking place because the energy
stored in the spring displac~s the wall.
The energy stored in the spring during the closed period
of the transfer passage 30 effects, when the passage is again
opçned, a very rapid transfer into the pump chamber 30 of the
volume of liquid which has bean stored in the pump chamber 17
during the same period. Because the transfer can take place
virtually without pressure drop, the spring need not overcome
any appreciable liquid pressure, and, besides, the mass that
the spring has to accelerate while stored energy is dissipated
is quite small; this mass is constituted by, in addition to
the movable wall and a portion of the spring, the mass of the
liquid stored i~ the pump chamber 17. There is also no tenden-
cy during the transfer to forming a vo~d which has to be
filled with liquid from the inlet tube 11. Therefore, the
inflowinq liquid in the inlet tube need not be accelerated but
can continue to flow direct into the pump chamber at the ~ame
velocity as beore.
3~,3
.J91/l9099 l'C~/SÆl91/aO411
- 12 -
In the illustrated embodiment the driving motor 21 and the
associated ball bearing screw-and-nut mechanism 22 accordingly
can be replaced by a spring arrangement which acts on the
piston 18 and continuously urges the piston upwardly. Such a
spring arran~ement suitably may subject the piston to an
upwardly directed force which is ~ubstantially independent of
.` the position of the piston over at l~ast the major part of the
~troke.
However, the illustrated embodiment including a piston
which is positively displaced upwardly may be preferable,
because it offers the possibility to arrange for the displace-
ment to take place in accordance with a certain time-travel
characteristic under the control by the control unit 60.
The just-described amplifying or booster effect on the
filling of the pump chamber 30 can also be accomplished, at
least partially, in a modification of the illustrated embodi-
ment comprising a positively displaced piston, namely by
adding to the feed piston pump 12 a spring arrangement of the
above-described kind. The simplQst way to realize this addi-
tion is to provide in the sho~k absorbing member 23 such aresiliency that it can serve as the described spring arrange-
ment. In such case, this spring arrangement and the piston 18
jointly effect the trans~er of the stored volume o~ liquid.
Those elements of the dispensing apparatus which are
contacted by the liquid ~orm a disposable unit which is wholly
or partly discarded and exchanged for a new one after it has
been u5ed for a certain time, such as for a work shiXt or some
other work period after which the packaging machine equipped
With the dispensing apparatus would normally have to be
cleaned. In the illustratQd embodiment, these elements are the
inlet tube 11, the outlet tube 15, the connector 52 for the
inlet.tube, the connector 53 (including the membrane 56) for
the outlet tube, the top pump housing part 40 with it5 top
section 40A and bottom section 40B, the membrane 42, the
pieton caps 18A and 26A and the valv~ member 35.
The disposable unit may ~e packaged in sterile condition,
and after the package has been opened, the disposable unit is
~ ' ' '.~ .
i
J~ 91/19099 PCr/SE91/OOql 1
~ 13 ~
positioned on the bottom pump housing part 41 to which it is
clamped by means of quick-connector clamps 41A which are
pivotally mounted on the bottom pump housing part. Initially,
the solenoid 59 and the valve member 57 are moved to the side
and they are then brought to the position 6hown in Fig. 1
after the disposable unit has been brought into position.
The appearance of the disposable unit in the configuration
it has when it is positioned on the bottom pump housing part
41 is shown in Figs. 2 and 3. The connectors 52 and 53 are
rotatably and removably connected with the top section 40A of
the top pump housing part through a bayonet coupling 52A, 53A
which includes a sealing ring 52B, 53B. In the packaged condi-
tion of the disposable unit the connectors are rotated to the
position shown in Fig. 2 to save ~pace~ From this position
they are swung to the operating position (Figs. 1, 3) after
the disposable unit has been positioned on the bottom pump
housing part 41.
The membrane 42 is secured to the sections 4OA and 4OB of
the top pump housing part 40 by heat ~ealing or ~ny other
suitable method; the just-mentioned ~ections are made of
plastic and likewise joined through heat sealing.
When the disposable unit is applied to the bottom pump
housing part 41, the bottom section 40~ of the top pump hous-
ing part 40 rests on the upper edge of the circumferentially
extending wall of the bottom pump housing part such that it is
accurately positioned also laterally (horizontally). The
partition 32, which separates the pump chambers 17 and 30 is
formed by a top portion belonging to the bottom section 40A of
the top pump housing part 40 and a lower portion belonging to
the bottom pump housing part 41. The first-mentioned portion
of the partition rests against the last-mentioned portion, as
shown.in Fig. 1. The valve member 35 re6ts on the push rods
37, and the piston caps 18A and 26A overlie the pi6ton heads
18B and 26B as is also shown in Fig. 1. Moreover, the valve
member 47 engages the me~brane 56 o~ the connector 53.
At its outlet end the ou~let tube 15 has an insert 65
which is provided with a large number of parallel, through-
91/19099 PCr/SEg1/0~411
going passages for the liquid to be dispensed. This insert 65prevents liquid from flowing out of the outlet tube a~ter the
pump piston 26 has reached its uppermost position.
In the sterile package which encloses the disposable unit
before it is used, the outlet end of the outlet tube 15, which
end is remote from the connector 53, is surrounded by a pro-
tective ~leeve 66 whi~h serves to preserve the sterility of
the interior sur~aces of the disposable unit aftex the package
has been opened in connection with the positioning of the
disposable unit on the bottom pump housing part 41. When the
inlet tube ll o~ the disposable unit has been connected to a
supply conduit, not shown, associated with the equ~pment
delivering liquid to the dispensing apparatus and operation of
the l~tter is commenced, the protective sleeve 66 will be
pushed away from the outlet tube by the pressure therein
during the first upward stroke of the pump piston 260
The end of the inlet tube ll which is ramote from the
connector 52, the inle~ end, is also provided with a surround-
ing protective sleeve 67, which preserves the sterility of the
interior surfaces of the disposable unit after the package has
been opened. Upon the mechanical interconnection of the dis-
posable unit and the supply conduit, the fluid conveying
passageway between the disposable unit and the supply conduit
i8 opened in the manner described below.
Mounted exteriorly of the connector 52 is an axially
displaceable conduit section 68 provided with a flange 69 at
the inner end, that is, the end closest to the top pump hou-
~ing part 40. Sealing rings 70 seal between the conduit sec-
tion 68 and the connector 52. The protective sleeve 67 in-
~ludes a tubular portion 71 which surrounds the outer end of
the conduit section 68, and the protective sleeve also has a
flange 72 at one end. Sealing rings 73 seal between the inside
of the protective sl~eve 67 and the outer 6ide of the conduit
section 68. A thin membrane 74 ~orms a fluid tight ~o~tom of
the protective sleeve at t~e end thereo~ remote ~rom the
flange.
,,: . .
~0 91/19099 PCI/SE~J1/00411
To interconnect the disposable unit and the supply con-
duit, the inlet tube is aligned with the outlet end of the
supply conduit, as is indicated in phantom lines in Fig. 1. By
means of a mechanism (not shown~, which does not form part of
the dispensing apparatus, an outwardly directed force is
applied to the flange 69 of the conduit section 68 so that the
conduit saction and the protective sleeve 67 thereon are
displaced toward the end of the supply conduit.
The protective sleeve 67 is stopped because its flange 72
engages an abutment while the conduit ~ection 68 is displaced
further. The end of the conduit section 68 then ruptures the
membrane 74 and is inserted over a certain distance in the
supply conduit and seals against the inside of the conduit ~y
means of the sealing rings 73. The membrane 74 may be provided
with suitable rupture line!:; in order that upon the rupturing
it may ~orm flaps which ~old against the outer side o* the
conduit section 68. The rupturing of the membrane along pre-
determined rupture lines may also be ensured if the free end
o~ the conduit section 68 has radial rupture members formed
by, for example, an insert provided with cutting edge members.
The arrangement for sterile sealing of the inlet tube 11
shown in the drawing~ is also use~ul in other application~
where an inlet tube is to be connected with a ~upply tube
while meeting strict requirements for hygiene.
In the illustrated and described embodiment, there is only
a single dosing piston pump which is filled from the storage
device formed by the feed piston pumpO It is also possible,
however, to provide the dispensing apparatus with several
dosing piston pumps, which are filled through individual
transfer passages from a common storage device or feed piston
pump in the above-described manner. ~he dosing piston pumps
can then be disposed in different ways in relation to the
storage device or feed piston pump t depending on the number of
dosing piston pumps and depending on what i~ suitable in each
individual ca~e, having rQgard to the e~uipment with which the
dispensing apparatus is to be used, such as in a row with the
.
2~ r~ ~
~91~19099 PCT/SE91/0~411
- 16 -
storage device or the feed piston pump positioned to one side
of the row, or along a circle or arcuate line.
As is evident from the foregoing description, the de-
scribed apparatus can also be used as a motor, the energy
suppli~d with the inflowing fluid being then primarily con-
verted to mechanical work and po~sibly further converted to
electrical energy, for example.
~ ,.
,
