Note: Descriptions are shown in the official language in which they were submitted.
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Device for Evacuating a Food Storage Container Closable bY a Valve ,.
This invention relates to a device in accordance with the prior-art portion of
patent claim
1.
The art knows of systems for storing food which allow the food to be preserved
under
better framework conditions than if it were stored without any treatment or
improved storage
conditions. One way to improve the storage of food is to keep it in containers
under vacuum.
Such systems have been shown to produce very good results in preventing
certain micro-
organisms, insect pests, mold and fungus growth. Furthermore, they help to
prevent the food
from oxidizing, thereby enabling variations in the moisture content and aroma
of the food to be
avoided.
To obtain such storage conditions a device is necessary which draws air out of
the stor-
age container in order to generate a vacuum. A wide variety of pumps for
performing this func-
tion are known from the art. As a rule the pumps intended for household use
are based on
piston pumps or ventilators.
U.S. Pat. No. 5,195,427 discloses a prior-art electrically powered handheld
vacuum
pump for use in the household. The handheld device is constructed from a
multiplicity of single
parts for use solely as a vacuum pump. In particular provision is made for an
elaborate conver-
sion of the shaft's rotary motion into an oscillating motion and for a
suitable reduction gear to
drive the piston pump. The system is intended for the evacuation of storage
containers for food.
With this device it is possible by easy means to obtain a suitable pressure
ratio for storing food
in a vacuum container.
From DE 195 04 638 A1 there is known an immersion blender for mixing or
comminuting
food whose blade rotates in a bell-shaped recess, thereby generating. a vacuum
which is pro
duced via a fluid connection from the upper part of the shank of the immersion
blender. The
vacuum accumulating in the bell serves to improve and intensify the mixing of
food.
From German utility model 299 20 316 U1 there is known a device for generating
a
vacuum in a container, using a vacuum-cleaner as a vacuum generator. For this
purpose use is
made of an adapter piece in the form of an attachment to a vacuum-cleaner,
which is mountable
on a valve arranged on the lid of the container. Handling the vacuum generator
constructed as
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a vacuum-cleaner is elaborate and complicated. Problems of hygiene may arise
when dealing
with food. ''
The electric vacuum pumps introduced for household use are very elaborate to
manu-
facture because rod mechanism and gearing require a large number of
components. The
structural configuration results moreover in relatively large dimensions of
the equipment. Fur-
thermore, purchasing a corresponding vacuum pump means that an additional
household
appliance has to be stored but is used in only a few cases.
It is therefore an object of the present invention to provide a device for the
evacuation of
storage containers for food which affords ease and greater economy of
manufacture.
This object is accomplished by a device for the evacuation of a food storage
container
closable by a valve having the features of patent claim 1. Advantageous
embodiments of the
invention are described in the subclaims.
The attachment of the invention for a handheld electric household appliance
has the ad-
vantage of providing a small, low-cost and easy-to-use vacuum pump for
household applica-
tions. Contrary to the solutions known from the art there is no need of a
completely new house-
hold appliance and equivalent additional storage space. Rather, the attachment
adds a further
useful component to the already existing attachments such as mixers, blenders,
etc. This is a
particularly space-saving solution and far cheaper than an additional electric
appliance with its
own drive. Furthermore, the attachment of the invention is easy and safe to
use in the domestic
field. The invention represents a simple and economical solution because the
two shaft ends
are joined together by positive engagement by simply plugging together the
shaft couplings. In
this arrangement the shaft couplings can be constructed as spur-toothed gears.
An advantageous embodiment of the present invention is provided by the
features of
patent claim 2. This type of vacuum pump features in particular a higher
suction power com-
pared to the vacuum pumps used to date for domestic applications. This means
furthermore
that the overall height can be small because there is no need of any elaborate
rod mechanisms
and gears. The vacuum pump can be directly driven with the rotational
frequency: of the drive
shaft of the household appliance. This also reduces the number of components,
which has a
positive effect in tum on the costs of manufacture. Finally, it takes just a
few seconds with such
a vane-type pump to generate the required level of pressure in a food
container.
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A further advantageous embodiment of the present invention is provided by the
features
of patent claim 3. In this arrangement the sealing lip is formed by a
circumferential edge of
elastomer plastic material projecting at the suction side. The cross section
of the sealing lip
may widen toward the free end. This makes it easier for the attachment to be
mounted on a
S suitable valve of a storage container for food. Locating it centrally
relative to a corresponding
valve opening, as is required with devices of the art, is thus eliminated. The
sealing lip works in
this case like a suction cup.
Yet another advantageous embodiment of the present invention is provided by
the
features of patent claim 4. The result is a simple and low-cost plug-type
connection with a
handheld household appliance such as an immersion blender. This plug-type
connection is
very sturdy and at the same time may serve as a centering arrangement for
connecting the
shaft couplings.
Finally, a further advantageous embodiment of the invention is provided by the
features
of patent claim 5. An additional safety function is thereby provided to
prevent liquid from enter-
ing the pump chamber during the evacuation operation. The solution is simple
and low-cost.
For example, it is possible to provide a simple spherical float in a riser,
which floats on the liquid
surface and closes a valve opening when the liquid has reached a predetermined
level.
An advantageous further aspect is also provided by the features of patent
claim 6.
Thereby the vacuum pump of the attachment is rendered temperature-resistant in
its operating
range. A self-lubricating effect is also achieved thereby. Consequently the
vacuum pump dis-
plays low pressure losses and requires no maintenance.
Yet another advantageous further aspect is provided by the features of patent
claim 7.
Temperature resistance within the operating range is thereby assured as
before. In addition to
this, however, the occurring centrifugal forces are withstood without any
deformations of un-
acceptable magnitude. This is also promoted by the material-related light-
weight construction.
Another advantageous further aspect is provided by the features of patent
claim 8. In
this arrangement, the lamellae configured, for example, as rectangular plates
may either be
freely movable, actuated solely by centrifugal force, or be exposed to spring
pressure: By suit-
able material selection a self-lubricating, maintenance-free construction is
made available.
Finally, an advantageous further embodiment of the attachment of the invention
is pro-
vided by the features of patent claim 9. This choice of material represents a
cheap hygienic
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construction that enables a multiplicity of designs. Some of the possible
materials are, for
example, polyethylene, polypropylene, polyamide or any other thermoplastic
material:
Further aspects and advantages of the present invention will be explained in
the sub-
sequent description of embodiments with reference to the accompanying
drawings. In the
drawings,
FIG. 1 is a schematic sectional view of a first embodiment of an invention
device for
evacuating a storage container for food;
FIG. 2 is a perspective exploded view of the device of FIG. 1;
FIG. 3 is a perspective detail view of the vane-type pump forming part of the
device of
FIG. 1;
FIG. 4 is a perspective view of an immersion blender with an attachment
according to
the embodiment of FIG. 1;
FIG. 5 is a schematic sectional view of a second embodiment of an invention
device for
evacuating a storage container for food with a float section; and
FIG. 6 is a graph showing, by way of comparison, the evacuation time for a 700
ml con-
tainer of an attachment of the invention and the evacuation time for
conventional vacuum
pumps for household use.
Identical or similar components will be identified in the following with the
same reference
characters.
FIG. 1 shows a schematic sectional view of an advantageous embodiment of an
attach-
ment 1 in accordance with the present invention. The attachment 1 has a
coupling section 2, a
pump section 3 and a suction section 4.
The coupling section is formed by a cup-shaped plug-in shank 6 and a coupling
gear 7
arranged within. The plug-in shank has in its base area a base opening 9
through which a shaft
8 connected with the coupling gear 7 is passed.
The vacuum pump arranged in the pump section 3 is constructed as a vane-type
pump
17, as shown in the perspective detail view of F1G. 3. The pump housing of the
vane-type pump
17 is formed by a graphite ring 16 which is covered at its upper and lower end
by a circular
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upper end disk 18 and a lower end disk 12, respectively. A cylindrical rotor
10 is eccentrically
mounted for rotation in the pump housing. The rotor 10 has an arrangement of
uniformly dis-
tributed radial grooves 32. Accommodated in the grooves 32 are radially
displaceable lamellae
11. The lamellae 11 are pressed against the graphite ring 16 by centrifugal
force, supported in
the present embodiment by the force of springs 26. This results in the
formation of fluid-delivery
cells 22 which become wider and narrower in a crescent-shaped configuration.
As becomes apparent from FIG. 1, the rotor 10 is connected to a shaft 8 which
at the
one end is passed through the end disk. The end of the shaft 8 projecting out
of the upper end
disk 18 has a coupling gear 7 constructed as a spur-toothed gear. Furthermore,
in coupling
section 2 provision is made for an annular sheath which continues along the
wall of the housing
5. This shaft-side housing end of the attachment 1, which is constructed as a
plug-in shank 6,
is intended for connecting to the tool-side end of an immersion blender.
Formed at the other end of the housing 5 around the outer circumference is a
circumfer-
ential sealing lip 13 made of an elastic rubber material, which is connected
via a groove 15 to a
1 S bar 14. The sealing lip 13 is constructed to act as a kind of suction cup
when in operation. The
cover 33 fitted to this end of the housing 5 has suitable suction slots 28.
The suction slots 28 lie
within the section of the cover 33 surrounded by the annular sealing lip 13.
FIG. 2 is a schematic exploded view of the embodiment of F1G. 1. It shows the
plug-in
shank 6 of essentially cup-shaped configuration in coupling section 2 and the
coupling gear 7
arranged at its bottom. Also shown schematically in the pump section 3 are the
rotor 10 and the
shaft 8 which connects the coupling gear 7 to the rotor 10. The rotor 10 is
received by the
graphite ring 16 which is arranged in tum in the housing 5. Finally, the
suction port 4 with the
sealing lip 13 made of elastomer plastic is shown at the lower end of the
elongated cylindrical
housing 5.
FIG. 3 shows schematically a perspective detail view of the vane-type pump 17
of FIG.
1. Visible is the opened upper end disk 18, which is made of graphite like the
cylindrical graph-
ite ring 16 and the lower end disk 12. Provided eccentrically to the center of
the circular upper
end disk 18 is a bore which acts as the shaft bearing 20 of the rotor shaft 8,
not shown. The
shaft bearing 20 is constructed as a self-lubricating plain bearing. The rotor
10 carried by the
shaft 8 is arranged within the cylindrical graphite ring 16 which together
with the upper end disk
18 and the lower end disk 12 forms the pump housing of the vane-type pump 17.
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The carbon-fiber rotor 10 is arranged eccentrically to the center of the
graphite ring 16.
It has three grooves 32 arranged at an angular offset of 120° to each
other, in which lamellae 11
are guided such as to be longitudinally displaceable in radial direction. The
lamellae 11 are
fabricated essentially as rectangular graphite plates. At their end facing the
shaft bore 21 of the
rotor 10 the lamellae 11 are acted upon by the pressure of compression springs
26. Also visible
is the suction opening 19 arranged on the lower end disk 12, through which air
is drawn out of a
storage container. The fluid-delivery cells 22 are formed by the rotor 10, the
upper end disk 18,
the lower end disk 12, the graphite ring 16 and the lamellae 11.
With the vane-type pump 17 in operation, the rotor turns with the shaft speed
of the im-
mersion blender 23. As the result of the centrifugal force and the spring
force the lamellae 11
slide along the inner wall of the graphite ring, hence guaranteeing that no
pressure compensa-
tion takes place between the various fluid-delivery cells.
FIG. 4 shows a perspective view of an attachment 1 of the invention, which is
mounted
on the output end of an immersion blender 23. The essentially elongated
cylindrical equipment
combination has at its upper end a grip 24 which can be gripped all-round by
the users hand.
On the front side of the immersion blender 23 in the upper region is an
actuating switch 25
which is easy to operate with the gripping hand.
In this arrangement the upper region of the housing 5 of the attachment 1,
which is con-
structed as a plug-in shank 6, is pushed over the slightly conical output end
of the immersion
blender 23: As this occurs, the shaft connection for driving the vacuum pump
is established
simultaneously.
A circumferential sealing lip 13 made of elastomer plastic is arranged on the
lower end
of the attachment 1. The smooth outer walls of the immersion blender 23 and
the attachment'1,
which are made of thermoplastic material, make it easy to clean the equipment
combination,
which is important for household appliances in particular for reasons of
hygiene.
The attachment 1 is connected during operation to the output end of the
immersion
blender 23. The attachment 1 is held by the annular shea#h at the output end
of the immersion
blender 23 such that it cannot tilt or twist. The output shaft of the
immersion blender 23 is in
positive engagement with the coupling gear 7 of the vane-type pump 17. The
suction. side of
the attachment 1 sits on a valve device which is arranged on a storage
container for food. The
circumferential sealing lip 13 sucks itself tight against a smooth
circumferential edge of a
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connecting arrangement of the valve device. While the storage container is
being evacuated
the rotor 10 of the attachment 1 is set in rotation by the drive shaft of the
immersion blender 23.
FIG. 5 shows a second embodiment of the present invention in which added
provision is
made for a float section 29. This prevents liquid from entering the vane-type
pump 17. In this
embodiment the constructional configuration of the coupling section 2 and the
pump section 3 is
essentially the same as the configuration described with reference to FIGS. 1
to 4.
In this embodiment a float section 29 adjoins the pump section 3. The float
section 29 is
essentially formed by a cylindrical float housing 31 made of thermoplastic
material. At its lower
end the float housing 31 has a bar 14 which engages in a groove 15 of a
sealing lip 13 forming
the suction port 4
A spherical float 30 is provided in the float housing 21. The float 30 is
constructed as a
hollow body so that it easily floats on inflowing liquid. When the level of
liquid in the float hous-
ing 30 reaches a critical value, the lower opening of the suction pipe 27 is
closed by the float 30.
No liquid then gets into the vane-type pump 17. Additional suction slots 28
are provided at the
1 S lower end of the float housing 31 in order to guarantee with certainty
that the air existing in a
storage container for food is evacuated.
FIG. 6 shows a graph in which the evacuation time for a 700 ml container is
presented.
The time t in seconds is plotted on the x-axis and the pressure in mbar on the
y-axis. At the
time t = 0 the pressure inside the container equals the ambient pressure. When
the vacuum
pump is activated, the pressure inside the container is reduced. The
development of pressure
as a function of time can be represented as a logarithmic function. Only when
using the em-
bodiment of the invention does it take just 5 seconds to attain a container
pressure of around
300 mbar, whereas comparable units attained only pressures of about 500 to 700
mbar during
this time period. After just 15 seconds with the attachment of the invention
the pressure
attained is 200 mbar and does not drop thereafter by any appreciable amount.
By contrast, the
comparable units attained only a pressure of around 300 to 400 mbar in the
same period of
time. This underlines the evacuating power and speed of the attachment of the
invention.
