Note: Descriptions are shown in the official language in which they were submitted.
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Metering pump
The invention relates to a metering pump for a metering device for
metered dispensing of a liquid, which can be connected to a storage
container, comprising a cylindrical pump body and an actuation body.
Metering pumps for metered dispensing of liquids which can be
connected to a storage container are known from the state of the art.
Such a metering pump which consists of a cylindrical pump body, an
actuation body and a closing cap is known from EP 0 473 892 A2 and
from EP 1 466 668 Al. An essential element of the metering pump
according to the above-mentioned European application is the
construction in the form of a pump body in hollow cylinder form which
has two portions, an inner hollow cylinder in which a piston is guided
being mounted in the interior of the hollow cylindrical pump body
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portion. The seal relative to the storage container is achieved by a
gasket disposed on the inside.
A similar solution is known from WO 97/18902 in which a sealing ring
is provided likewise for the seal between the storage container and the
pump body in the form of a hollow cylinder.
It has however been shown that such arrangements still display
inadequate reliability with respect to the impermeability against air
penetrating during the metering process. Furthermore, there are
problems during the metering if a storage container with a high
temporary counter-pressure is used.
It is therefore the object of the present invention to indicate a metering
pump for medical, pharmaceutical and cosmetic liquid and gel
preparations and also in the foodstuff sphere (e.g. for food supplements,
herbs/spices, etc.) which can be connected to a storage container and
in the case of which increased reliability of the impermeability against
air penetrating during the metering process is achieved even under
unfavourable circumstances.
The object is achieved by the characterising features of patent claim 1.
The sub-claims reveal preferred developments.
According to the invention, it is proposed hence according to patent
claim 1 that a metering pump which can be connected to a storage
container, as is known already in the state of the art, e.g. from EP 0 473
892 A2, from EP 1 466 668 Al or from WO 97/18902, is improved such
that a sealing ring for the seal is provided between the outside of the
piston and the inside of the pump body on the pump body on the inside
itself. Furthermore, the metering pump according to the invention is
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distinguished by a valve portion being provided on the open end in the
direction of the storage container, in which valve portion an inlet valve
cooperates, according to the invention, with a ball disposed in a valve
seat.
It is now achieved by the combination of these measures that even
under unfavourable conditions during the metering process, i.e. at high
temperatures and counter-pressure, extremely high impermeability is
achieved. Furthermore, it has been shown that also a significantly
simplified actuation of the metering pump is made possible by the
configuration according to the invention such that the pumping process
need not be implemented many times, as is normal in the state of the
art, for the filling process, but rather that, even after a few pumping
processes, generally after three to four times, reliable and perfect
metering is possible.
A particularly advantageous embodiment of the metering pump now
provides that, in the interior of the valve portion, starting from the
inside, support elements which extend in the longitudinal direction are
provided for upper path delimitation of the ball during actuation of the
metering pump. As a result, extremely reliable guidance of the ball in
the space spanned by the valve seat and by the support elements
becomes possible. This measure in particular obviously leads to the
fact that, as explained already above, an extremely reliable operation is
possible with the metering pump according to the invention. For this
embodiment, it has emerged as particularly favourable if at least one,
preferably two, however particularly preferred three, support elements
are provided. These support elements are preferably configured such
that they are connected in one piece (monolithically) to the inside of the
inner hollow cylinder which defines the valve portion. Preferably, these
support elements are thereby produced in one piece together with the
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valve seat and the inner hollow cylinder, at least of the valve portion,
preferably by an injection moulding process.
The advantage of the thin configuration of the wall in this region is
higher flexibility of this valve portion.
This increased flexibility makes it possible to counteract the "suction
force/restoring force" which is produced by the inner bag (disposed in
the storage container) after actuation of the pump (tendency of the inner
bag to return into a relaxed form instead of remaining in folded form).
This means that the contact region of the valve wall with the ball seals
even more tightly due to the increased flexibility and prevents the
entrance of air in the direction of the bottle. In the case of a thicker
wall, the result can be gaps in the region between the contact area of
ball to valve so that air can enter. In particular, this is the case with
balls which are not optimally round or with irregularly coated balls.
In the case of the support elements, there are included all possibilities
which are known per se in the state of the art and lead to stabilisation
of the ball. Preferred support elements are those which are configured
in a wedge shape.
Of further importance, it has emerged that at least the valve portion is
configured such that the thickness of the walls of the valve portion is in
the range of 0.2 to 1.0 mm, preferably in the range of 0.3 to 0.5 mm.
The simplified production in the injection moulding process is thereby
advantageous. The reproducibility of the shape of the support elements
is increased as a result and hence allows precise function and mobility
of the ball. An essential element in conjunction with this embodiment
is hence the configuration in the form of thin walls within the indicated
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limits. If the upper limit of 1..0 mm is exceeded, it has emerged that this
can lead to a lack of seal in subsequent use. In addition, the rigidity is
so high that the flexibility of the wall is reduced too far still to seal the
ball reliably. With smaller thicknesses than 0.2 min, adequate
stabilisation cannot be achieved.
In a further preferred embodiment, coating the ball is proposed. The
coating of the ball is effected in a thin layer which is placed around the
ball over the whole surface. Suitable materials for this are in particular
LD-PE (Low-Density-Polyethylene). An improvement in the metering
effect is achieved by this measure. Coating with this material which is
authorised for medical applications enables the authorisation of a
medical product in markets which have particularly strict regulations.
The ball itself can consist for example of stainless steel or a ball coated
with silver which is then germicidal.
The gasket which is proposed according to the invention is a sealing
ring in a preferred embodiment.
The sealing ring, according to the present invention, is disposed on the
inside of the hollow cylindrical pump body portion which points in the
direction of the actuation body. The arrangement should thereby be
chosen such that as high a sealing effect as possible is achieved relative
to the piston which is guided in the interior of the hollow cylinder. The
sealing ring can also be present as an integral component in the
corresponding pump body portion.
In a favourable manner, the sealing ring is therefore configured such
that it is at a spacing from the piston outer wall and has suitable
sealing lips. The impermeability relative to the piston is then achieved
by these sealing lips. The sealing lips can thereby be configured as
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individual separate lips and point in the direction of the actuation body.
The sealing ring can thereby have at least one, preferably 3 to 5 lips.
A development of the invention proposes that, for reliable mounting of
the sealing ring in the interior of the hollow cylindrical pump body
portion, the sealing ring is configured in profile in the shape of a U and
one U-leg engages in a groove on the interior of the pump body portion.
The second leg of the U is then used for the sealing effect. This second
leg of the U can then also be configured such that it is at a spacing
relative to the outside of the piston and produces the sealing effect via
lips.
From the point of view of choice of material, basically all materials can
be used which are used in general for gaskets. The choice of material
thereby depends upon the safety for the respective field of use.
Thermoplastics and thermoplastic elastomers are possible. Examples
are PTFE (polytetrafluoroethylene), PU (polyurethane), polyamide (PA),
polyethyleneterephthalate (PET), LD-PE (low density polyethylene), HD-
PE (high density polyethylene) and PP (polypropylene).
The metering pump according to the invention can even of course, as in
the state of the art, also have an additional gasket for the seal relative to
the storage container. It is thereby preferred that a gasket is disposed
internally between, on the one hand, the inner hollow cylinder and the
cylindrical pump body portion and, on the other hand, the storage
container, not illustrated.
The cylindrical pump body is formed preferably from a plastic material,
such as e.g. polypropylene (PP) or polyethylene (PE). Of importance for
the choice of material are thereby the medical and pharmaceutical
safety and also the material safety in the foodstuff sphere. The inner
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surface of the cylindrical pump body can therefore also have a coating
for germicidal purposes.
The invention also includes an embodiment analogous to EP 1 466 668
Al in which the inner hollow cylinder which forms the pressure
chamber can be exchanged.
The metering pump according to the invention has then of course also
an actuation body which is connected to the piston and to the
cylindrical pump body. The configuration of the actuation body is
thereby likewise based upon the state of the art. Reference is made in
this respect to EP 0 473 892 A2, EP 1 466 668 Al and also WO
97/18902.
There are basically possible as storage container which can be
connected to the metering pump, all storage containers of the state of
the art. Reference is made in this respect to the documents mentioned
in the preceding paragraph. These must enable operation without air-
equalisation, i.e. for example containers with a flexible inner bag or drag
piston. In addition to cylindrical containers manufactured from stable
plastic material, also plastic material bags which are integrated in a
separate container are suitable. When using drag piston bottles, a
lower pressure should be expected.
The storage containers are favourably connected to the metering pump
via a snap-on closure or via a thread.
The invention is described subsequently in more detail with reference to
Figures.
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Figure 1 shows an embodiment with the sealing element according
to the invention.
Figure 2 shows the sealing element of Figure 1 according to the
invention in enlarged form.
Figure 3 shows an embodiment in which the sealing element is
configured in the form of a U.
Figure 4 shows the sealing element of Figure 3 according to the
invention in enlarged form.
Figure 5 shows, as a cut-out, the configuration of the valve region
with the sequence of Figures 1, 2, 3 which show the
different operating states.
Figure 6 shows the dimensioning of the valve region.
Figure 1 shows schematically the construction of a metering pump
according to the invention, the cylindrical pump body 1 with the
actuation body 20 being represented here for the metering pump. The
actuation body 20 which can consist preferably of the same material as
the cylindrical pump body, i.e. for example PE, is connected to the
pump body 1, e.g. via a snap-on closure or a plug-in connection. In
Figures 1, 2, 3 and 4, the storage container is not illustrated since it is
not essential for understanding the invention. For this purpose, as also
for the explanation of the actuation body 20, reference is made to EP 0
473 892 A2, EP 1 466 668 Al or WO 97/18902.
In Figure 1, the cylindrical pump body 1 of a metering pump with the
actuation body 20, as known from state of the art, is illustrated. The
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cylindrical pump body 1 thereby consists of a hollow cylindrical pump
body portion 2 which is open in the direction of the storage container
(not illustrated) and a second hollow cylindrical pump body portion 3
which is open in the direction of the actuation body 20. A groove
disposed on the inner wall of the portion 3 is thereby designated with
15. An inner hollow cylinder 4 is mounted between the pump body
portions 2, 3. Mounting of the inner hollow cylinder 4 in the pump
body portions 2 and 3 is effected, in the embodiment according to
Figure 1, by engagement in a groove. As emerges further from Figure 1,
a piston 5 is guided in the inner hollow cylinder 4. The piston 5, as
known from the state of the art, is thereby supported in the interior of
the hollow cylinder 4 via a spring 9. The inner hollow cylinder 4 here
now has an inlet valve 6, the inlet valve 6 being configured with a ball 8
which cooperates with a valve seat 7. The valve region is thereby
designated with 30. In order to ensure the air-tight seal between the
storage container (not illustrated) and the surroundings, a gasket
arrangement 10 is provided on the lower side in the drawing. The
sealing element 11, which is essential to the invention, is thereby
configured, as emerges in particular from Figure 2, in the shape of a
ring and is mounted on the inside of the hollow cylindrical pump body
portion 3 and preferably at a spacing relative to the outer wall of the
piston 5.
For improving the sealing effect, sealing lips 12, 12' which produce a
reliable seal even against air penetrating during the pumping process
are provided, as emerges from Figure 2. The invention thereby includes
of course also embodiments in which at least one sealing lip is provided.
In a modification of the embodiment, as was described in Figure 1 or
Figure 2, Figure 3 now also shows that the sealing element 11 is
configured in the shape of a U. In this embodiment, the sealing ring 11
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is mounted by the one U-leg in a groove 15 on the inside of the pump
body portion 3. The second U-leg functions as sealing element relative
to the outer wall of the piston 5. In the embodiment according to Figure
3, sealing lips 12, 12' are also provided again in order to enable optimal
guidance of the piston in the interior of the hollow cylinder 4 and a seal.
In Figure 4, a partial region of the embodiment represented in Figure 3
is illustrated enlarged. The sealing lips 12, 12' are provided for
improving the sealing effect. These enable reliable sealing also against
air penetrating during the pumping process. The sealing ring 11 is
present here in the shape of a U.
Figure 5 shows, in a cut-out, the configuration of the valve region 30
with the sequence of Figures 1, 2 and 3 which illustrate the different
operating states during actuation.
In Figure 5, the support elements 31 are thereby illustrated in a wedge
shape. The support elements 31 and also the valve seat 7 are thereby
configured integrally with the inside of the inner hollow cylinder 4.
Such a configuration is preferably achieved by producing at least the
part of the inner piston which is defined by the valve region 30 in one
piece made of a suitable plastic material by means of an injection
moulding process. By means of the configuration of the valve region 30,
as described above, it is now achieved that reliable closure of the valve
6, as illustrated in the sequence of Figures 1, 2 and 3, is achieved
during actuation of the piston. The sequence of Figures 2 and 3 then
shows the change in the position of the ball 8 during actuation of the
metering pump and the mode of operation of the wedge-shaped support
elements 31 which lead to reliable and defined securing of the ball 8.
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A further essential element of the invention resides, as illustrated in
Figure 6, in the valve region 30 being formed by a relatively thin-walled
inner hollow cylinder 4. The thickness of the wall of the valve portion
30 of the inner hollow cylinder 4 is thereby preferably in the range of
0.2 to 1.0, particularly preferred in the range of 0.3 to 0.5 mm. It was
shown that, in the case of this thin material thickness, an optimum
flexibility is achieved, yet with adequate stability in order that the valve
seat achieves optimum adaptation of its shape to the ball but still holds
it securely. As a result, the seal is achieved. According to the
invention, the metering pump is therefore configured such that the
above-mentioned dimensions of the walls of the inner hollow cylinder
are maintained at least in the region of the valve region.
