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Description  |
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FIELD OF THE INVENTION
The invention relates to a cap for dosing a predetermined amount of cream
or gelatinous product and in particular a cap for dosing amounts from a
collapsible tube of product.
BACKGROUND OF THE INVENTION
In packaging of pastes, creams, and topical ointments, a collapsible tube
is often used. The packaging permits storage of the product in the absence
of air and other possible contaminants. Tubes are made from drawn metal or
laminated foils and films depending on the characteristics desired of the
tube and the sensitivity of the contents to contamination by external
elements.
One drawback of collapsible tubes and the products contained therein is the
inability to quickly and accurately measure quantities dispensed from such
tubes. Usually, such tubes hold viscous pastes, creams, gels and the like
which do not flow easily. Therefore, such substances are difficult to
dispense in accurate amounts.
The viscous nature of the substances can cause a user to believe that he or
she has a certain quantity of dispensed when the actual amount is far
greater or far less. This has leant itself to often describing the amount
of product dispensed in terms of the length of a strip of product extruded
by squeezing the collapsible tube. However, this method is subject to each
individual's perception of length and the substantial errors associated
therewith.
U.S. Pat. No. 2,904,227 discloses a metering device for a squeeze-type
container. The device uses a piston and metering chamber structure. The
piston uncovers the metering chamber when the piston is in a first
position. Movement of the piston to an extended position closes off the
metering chamber and dispenses fluid through a conduit having end ports.
The disclosure explains that the device is limited to low viscosity
substances. The device relies on the internal container pressure to move
the piston. In use, it is difficult to tell whether the piston has fully
extended or to provide sufficient pressure to dispense high viscosity
products such as creams and pastes.
U.S. Pat. No. 3,338,475 discloses a device for dispensing liquids or
creams. The device operates in the form of a single shot pump. That is,
the device has a resilient pump unit with a check valve at each end. The
unit is squeezed to force the product out through the check valve at the
outlet end. The resiliency of the unit then expands the chamber closing
the outlet check valve and pulling product into the chamber through a
check valve at the container neck. The resiliency of the unit must be
sufficient to pull viscous substances from the container. Thus, the more
viscous the substance, the more force that is necessary to overcome the
resiliency of the unit. Furthermore, there is no positive indication of
when a "dose" has been administered. Rather, the dose size is a function
of the size and strength of the user's fingers as well as the depth of the
compression of the unit.
U.S. Pat. No. 4,376,495 describes a device for dispensing an adjustable
dose from a flexible container. The device has a hollow piston structure
which moves within a neck of a container. The piston moves to a position
against stops at the end of the neck to prevent further flow of container
contents. To reset the dose, a central pin is inserted to push the piston
back. A valve in the piston is concurrently opened to permit flow of a
portion of the contents from one side of the piston to the other thus
allowing piston movement. The initial position that the piston is returned
to determines the quantity of contents dispensed at the next usage.
Other U.S. patents disclosing valve or dosing assemblies for dispensing
containers are U.S. Pat. Nos. 4,564,131 and 4,607,762.
The above-described devices lack an ease of operation and a reliability
necessary for many consumer products. A consumer must be able to easily
and quickly determine that an appropriate amount of a substance has been
dispensed, but the described devices lack the requisite ease of operation.
SUMMARY OF THE INVENTION
The invention relates to a dosing and dispensing apparatus which supplies a
measured dose of a viscous product from a container. The apparatus is
sealingly attached to the container by, for example, a threaded or snap
connection.
A conduit of the apparatus extends from the container and communicates with
the contents of the container. When product is expelled or drawn out of
the container, it is directed through the conduit.
At an end of the conduit is an expandable dosing chamber. The dosing
chamber receives product which flows from the container through the
conduit. The dosing chamber has a predetermined minimum and maximum
volume. Advantageously, the dosing chamber may be formed by a slidable cap
which is telescopingly received on the conduit. The cap slides between
expanded and contracted positions which respectively define the maximum
and minimum dosing chamber volumes.
A check valve is associated with the conduit and prevents flow of product
through the conduit into the container when the dosing chamber is
collapsed.
A discharge opening is defined by the dosing chamber through which product
contained in the dosing chamber is discharged when the chamber is
collapsed. The flow through this opening is controlled, however, by a back
pressure means. The back pressure means prevents flow through the
discharge opening when the pressure within the chamber is at or below the
pressure necessary to expand the chamber and permits flow at pressures
greater than that necessary to expand the chamber. Thus, product being
transferred into the chamber will not exit the chamber until the chamber
is fully expanded. Any attempt increase in internal pressure merely
expands the chamber which in turn prevents the pressure from expelling the
product.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the accompanying
figures wherein:
FIG. 1 is a partial perspective view of a collapsible container having the
device of the present invention attached thereto;
FIG. 2 is a partial perspective view of the dosing apparatus of the present
invention in its initial, collapsed position;
FIG. 3 is a partial perspective view of the dosing apparatus of the present
invention in its expanded position;
FIG. 4 is a partial perspective view of the dosing apparatus of the present
invention discharging a dosed amount of product;
FIG. 5 is an exploded view of the apparatus of the invention;
FIG. 6 is a longitudinal cross-section of the apparatus of the invention;
FIG. 7 is a longitudinal cross-section of the apparatus showing discharge
of a dosed amount of product from the apparatus;
FIG. 8 is a longitudinal cross-sectional view of the apparatus showing an
alternative embodiment;
FIG. 9 is a top plan view of the check valve of FIG. 8; and
FIG. 10 is a cross-sectional view of FIG. 9 along line 10--10.
DETAILED DESCRIPTION
Referring to FIG. 1, a collapsible tube 10 is shown having dosing device 11
on its open end. Dosing device 11 has a protective overcap 12 which
protects the devices mechanism until ready for use and maintains the
integrity of the product. The overcap 12 may be provided with a piercing
means 13 to pierce a foil of film (not shown) which seals the neck of the
tube 10 prior to initial use.
Upon removing the overcap 12, the device 11 is in its initial collapsed
position (FIG. 2). That is, cap 14 is contracted down onto the device base
15. Base 15 has external threads 16 which mate with internal threads on
overcap 12 to hold the overcap on the device. Thus, the overcap 12 is
simply removed by twisting.
Base 15 has internal threads 16A to attach the device to the threaded neck
of tube 10. Base 15 has a cylindrical conduit 17 (FIG. 5) extending
longitudinally. Conduit 17 is open at both ends and communicates with the
internal volume of tube 10. Thus, squeezing of the tube 10 will cause
product contained within the tube to be forced through the conduit 17 and
out of end 18.
End 18 receives thereon flapper valve 19. The valve has a depending
cylindrical skirt 20 (FIGS. 5 and 6) which receives end 18, and is made of
an elastomeric material such as rubber. The depending skirt 20 has an
inner diameter slightly smaller than the diameter of conduit 17 adjacent
end 18. At the end 18 of conduit 17, a circumferential lip 21 is formed.
The lip may extend around the entire circumference of conduit 17 or only
partially about the circumference. Skirt 20 has an enlarged inner diameter
adjacent the valve end of the skirt. This enlarged diameter forms a
portion for receiving lip 21 of conduit 17 when the valve 19 is received
thereon. Because the skirt's inner diameter is slightly smaller than that
of the conduit 17 adjacent end 18, the skirt is received on the conduit by
elastic stretching of the skirt 20. Once on conduit 17, the valve 19 is
held in place by the interaction of lip 21 and the enlarged inner diameter
of skirt 20. Additional holding force is provided by the frictional grip
of the conduit surface provided bY the valve skirt's elastic tendency to
return to its original diameter.
Cap 14 is cylindrical in shape and is slidably received on conduit 17 in a
telescoping manner. Cap 14 has a depending skirt 22 which has an inner
circumferential surface 23. Adjacent open end 24, the surface 23 has a
circumferential rib 25. Rib 25 defines an inner diameter approximately
equal to the diameter of outer surface 23a of the conduit 17. Conduit 17
has an outwardly extending rib 26 which defines an outer diameter greater
than the inner diameter of rib 25. Thus, as the cap 14 is slidably moved
relative conduit 17, the ribs 25,26 interfere with one another preventing
removal of cap 14 from conduit 17 and establishing a maximum point of
movement of cap 14.
Skirt 20 of the flapper valve 19 forms a pair of circumferential
protuberances 27. The protuberances 27 act as integrally formed seals in
the same manner as conventional O-rings. The protuberances act both
statically and dynamically, that is the seal operates when the pressure
increases within cap 14 and the cap is held in position or when the cap 14
is moving relative conduit 17. The protuberances have an outer
uncompressed diameter at least equal to and preferably greater than the
inner diameter defined by surface 23. Thus, when cap 14 is placed over
conduit 17, the protuberances 27 are slightly compressed forming a
positive surface contact seal.
In the center of valve 19 are a pair of semi-circular shaped flapper arms
28. Arms 28 are formed by two arcuate openings 29 defined in the valve
member 19. The arms 28 remain attached to the remainder of the valve 19 by
strips 30. The arms 28 form a disc shape having a diameter greater than
that of opening 31 in end 18 of conduit 17. Thus, when valve 19 is placed
on end 18, the arms 28 overlap the edge 32 of end 18. Edge 32 supports
strips 30 and forms a seat for arms 28. When the pressure within the
conduit is greater than the pressure on the opposite side of the valve 19,
the flapper arms 28 flex resiliently away from edge 32 opening end 18 of
conduit 17. When the pressures on opposite sides of the valve equalize the
arms 28 return to seat on edge 32, sealing the conduit. When the pressure
on the outside of the valve is increased above that within the conduit,
the arms 28 are forced against edge 32 forming a tighter seal and
preventing flow into the conduit through end 18.
Cap 14 defines an opening 33 at an end opposite end 24. This opening may be
sized so that a viscous product would not flow therethrough absent a
pressure difference from one side of the opening to the other which is
sufficient to move cap 14 along conduit 17 from its fully collapsed
position to a fully expanded position. Preferably, the opening receives a
means for maintaining a pressure difference between the interior of cap 14
and its exterior such as a slit valve 34.
Slit valve 34 is formed of an elastomeric material such as rubber. The slit
valve 34 has a membrane section 35 which substantially blocks opening 33
and sealingly engages cap 14. A membrane section 35 defines an opening
such as slit 36. The slit 36 is normally closed, however, when the
pressure on the inside of the cap 14 is greater than the pressure on the
outside by an amount sufficient to overcome the elastic forces of the
membrane section 35 which hold the slit closed, the slit 36 opens
permitting a substance to pass therethrough to equalize the pressure. The
size of the slit 36 and elastic properties of membrane section 35 define
the force necessary to open slit 36. The cap parameters are chosen so the
force necessary to open the valve is greater than that necessary to move
cap 14 from its contracted position to its expanded position. It is easily
seen, therefore, that the force on the valve will not be great enough to
open slit 36 until the cap 14 reaches its fully extended position. Until
fully extended, any pressure differential between the inside and outside
of the cap are equalized by the telescoping motion of the cap.
Slit valve 34 has a flange 37 spaced from and diverging from the plane of
membrane section 36. Cylindrical trunk 38 spaces the flange 37 from
membrane section 36 and defines a groove 39. Groove 39 receives and holds
first positioning rib 40 which extends around and radially into opening
33. A second positioning rib 41 extends around and radially into the
inside of cap 14. Second positioning rib 41 is spaced from the inside top
surface 42 of cap 14. The space defined between second positioning rib 41
and top surface 42 receives the outer circumferential edge 43 of flange
37. Thus, when slit valve 34 is flexed into position within cap 14, it is
held in position by first and second positioning ribs 40,41. The slit
valve 34 is held in position with flange 37 in face to face surface
contact with top surface 42. Thus, the surface contact forms a seal which
increases in sealing force when the pressure within cap 14 increases and
forces flange 37 against top surface 42. It should be noted that although
the valve 34 has been described with a slit opening, many different
openings, such as a pin hole for example, will work. The opening
configuration and size is determined by the elasticity of valve 34 and the
viscosity of the product to be dispensed. Even a rigid opening having no
valve 34 may be used to dispense very viscous substances which will not
flow easily through a small opening except through a pressure differential
which exceeds that necessary to telescope cap 14.
The operation of the device will now be described with reference to the
sequence in FIGS. 1, 6 and 7. Initially, the tube 10 is sealed by an
occlusion seal of its neck and the dosing device is separated from the
tube neck. Piercing means 13 is thrust into the neck to pierce the seal
leaving a marginal remainder 44. The dosing device 11 is then threadedly
attached to the neck of tube 10. Initially, cap 14 is fully contracted
upon conduit 17 (FIG. 2). Upon squeezing the tube 10, the viscous product
contained within the tube is forced up through the neck of the tube and
then through conduit 17 (FIG. 6). When the product reaches the underside
of flapper valve 19, further squeezing of the tube forces arms 28 away
from edge 32 permitting passage of the product from the conduit 17 into
the volume defined between the cap 14 and the valve 19.
As the pressure increases within the dosing chamber, that is the space
defined between the cap 14 and valve 19, the cap 14 telescopes upward
along conduit 17. The increase in volume caused by the telescoping cap is
filled with product from the tube.
Once the cap 14 telescopes to a point where rib 25 meets rib 26, the ribs
25,26 interfere with one another to prevent further movement of cap 14.
Continued squeezing of tube 10 will cause a small amount of product to
escape through slit valve 34, signaling the user that a full dose is ready
to be dispensed.
In order to dispense the product from the dosing chamber, cap 14 is pushed
down onto conduit 17. Flapper valve 19 closes in response to the pressure
increase within the dosing chamber caused by the decreasing volume. Slit
valve 34 is forced open by the pressure and the product is extruded
through slit 36. A full dose is dispensed when cap 14 is fully contracted
onto conduit 17 thus decreasing the dosing chamber volume to its minimum
volume.
The size of the dose dispensed is the difference between the maximum volume
of the dosing chamber (i.e. when cap 14 is extended to the point where the
ribs 25,26 meet) and its minimum volume. By changing the dimensional
parameters of the cap and conduit, an appropriate dose volume may be
provided for the particular product, in particular volumes in excess of
0.05 cc may be readily dispensed. After dispensing, the overcap is
returned to the apparatus to cover and protect the apparatus.
An alternative embodiment is depicted in FIGS. 8-10. In particular the
flapper valve has been replaced by a stopper valve 45. Stopper valve 45
has a central stopper 46 which plugs opening 47 of conduit 17. The stopper
46 is attached to a depending skirt 48 by connecting strips 49. The valve
45 may be fabricated by, for example, molding elastomeric material. The
material must have sufficient elasticity to permit strips 49 to flex as
stopper 46 moves out of opening 47 in response to a pressure differential
across the stopper.
Skirt 48 has a circumferential protuberance 50 and circumferential wing 51.
Wing 51 is shaped in an upwardly extending configuration. Thus
protuberance 50 acts as an O-ring as described in connection with
protuberance 27. Wing 51, however, is pressed against the wall of cap 14
as the cup slides downward on conduit 17 by its shape and by the
frictional forces between the cap and wing. Also the increased pressure
within the chamber during dispensing forces wing 51 outward. Thus the
movement of the cap and pressure of the product during dispensing increase
the force pressing wing 51 against the cap surface. As in the flapper
valve, the stopper valve is provided with a circumferential groove 52.
Groove 52 receives lip 53 when the skirt is placed over the conduit. The
valve 45 is held in position by the frictional forces between the skirt
and conduit, and by the engagement of lip 53 and groove 52.
* * * * *
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Description |
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