Abstrict An improved arrangement in a liquid flow meter which contains at
least one cylindrical measuring means rotating in a measuring chamber
with the measuring means sliding with its one end face against a
bottom part of the measuring chamber in which a stable, bell-shaped
stiffening element rests against the edge of the bottom part and
is arched thereover on the side facing away from the measuring chamber
with a rigid connecting member attached to the bottom part and the
stiffening element at least in the central region of the bottom
part. Preferably support ribs with an external shape corresponding
to the inner contours of the bell-shaped stiffening element are
connected firmly with the bell-shaped stiffening element.
Claims What is claimed is:
1. In a liquid flow meter through which can be passed both warm
and cool liquids, the meter including a measuring chamber having
base members between which at least one rotatable measuring member
having end-faces is mounted so that the end-faces glide along the
base members when the measuring member is rotated, the improvement
comprising: a support structure for at least one of the base members
to prevent the same from deflecting inwardly in response to the
warm liquid whereby jamming of the rotatable member is precluded,
said support structure including a bell-shaped stiffening member
arranged at the side of the base member facing away from the measuring
chamber, said stiffening member being joined to the base member
about the periphery thereof; and, a rigid connecting member joining
the apex region of said bell-shaped member with the center region
of the base member.
2. A liquid flow meter according to claim 1 and further including
support ribs having an external shape corresponding to the inner
contour of the bell-shaped stiffening element firmly connected to
said bell-shaped stiffening element.
3. A liquid flow meter according to claim 2 wherein said support
ribs are further connected to a support element attached at the
center of said bell-shaped stiffening element.
4. A liquid flow meter according to claim 3 wherein said support
element is a tube section surrounding said connecting member.
5. A liquid flow meter according to claim 3 wherein said support
element is said rigid connecting member.
6. A liquid flow meter according to claim 1 wherein said bell-shaped
stiffening element has the shape of a spherical segment.
7. A liquid flow meter according to claim 6 wherein said bell-shaped
stiffening element is shaped as a hemisphere.
8. A liquid flow meter according to claim 1 wherein said bell-shaped
stiffening element is a member having a compound-curve shape.
9. A liquid flow meter according to claim 1 wherein said bell-shaped
stiffening element has the shape of a domed head.
10. A liquid flow meter according to claim 1 wherein a rotary-piston
is the measuring means and is guided in a ring chamber by a journal
therein and wherein said journal is arranged to extend from said
measuring chamber through said bottom part, the extension of said
journal forming said rigid connecting member and being rigidly attached
and sealed into said bottom part and rigidly attached to said bell-shaped
stiffening element.
11. A liquid flow meter according to claim 10 and further including
support ribs having an external shape corresponding to the inner
contour of said bell-shaped stiffening element firmly connected
thereto and to said extension of said journal.
12. A liquid flow meter according to claim 11 wherein said stiffening
element is welded to said bottom part and said connecting member
is welded to said bottom part and to said bell-shaped stiffening
element.
13. A liquid flow meter according to claim 1 wherein said stiffening
element is welded to said bottom part and said connection member
is welded to said bottom part and to said bell-shaped stiffening
element.
Description BACKGROUND OF THE INVENTION
This invention relates to liquid flow meters of the type having
at least cylindrical measuring means rotating in a measuring chamber
and sliding with its end face along a bottom part of a measuring
chamber in general and more particularly to an improved arrangement
for such flow meters.
Liquid flow meters of this type are generally known as rotary-piston
flow meters, driven-slide flow meters and oval-wheel flow meters.
In a flow meter of this type if a relatively warm liquid for example
a liquid at 90.degree.C, suddenly flows through the meter a danger
exist that because of thermal expansion a binding of the measuring
means will take place thereby damaging it. Damage can be to the
extent that the measuring means must be replaced. A problem like
this typically arises with meters employed in the food industry
such as milk meters where a hot rinse for cleaning purposes is performed.
In view of this problem the need for a liquid flow meter which
can be operated without of seizing the measuring means even where
relatively warm liquid suddenly flows through the meter is clear.
SUMMARY OF THE INVENTION
The present invention provides such a construction. In essence
the solution of the present invention resides in the provision of
a bell-shaped stiffening element which arches over the bottom part
of the side facing away from the measuring chamber. The bell-shaped
stiffening element is attached to the edges of the bottom part and,
at least in the central region of the bottom part, a rigid connecting
member is attached between the bottom part of the measuring chamber
and the stiffening element. It is possible for the bell-shaped stiffening
element to be connected with a positive fit to the bottom part.
However a welded connection is clearly advantageous.
The present invention is based on the discovery that seizing of
the measuring means when relatively warm liquids suddenly flows
through the flow meter is caused by the fact that the planar bottom
parts at the end faces of the measuring chamber buckle inward due
to thermal expansion. In such instrument the clearance between the
end face of the measuring means and the bottom part, which must
be kept small for reasons of measurement technology, then becomes
zero and binding of the measuring means takes place. The inward
buckling of the bottom part is initially subjected to an elevated
temperature thereby causing thermal expansion to occur initially
only in the inner layer. At this point the outer layers of the bottom
part are not subject to thermal expansion. As a result the inner
layers of the bottom part become longer than the outer layers leading
to buckling of the bottom part inward.
With the construction of the present invention the bell-shaped
stiffening element in combination with the rigid connecting member
prevents this buckling of the bottom part inward when it is warmed
due to the inflowing relatively warm liquid. This results because
the stable, bell-shaped stiffening element, due to its very great
stiffness, keeps the bottom part in its desired planar shape. Even
when a relatively warm liquid suddenly flows into the flow meter,
such as occurs in the hot rinsing of a milk meter, no buckling of
the bottom part inward and thus no seizing of the measuring means
can take place.
It should be noted that a solution to the problem might consist
of feeding the liquid flowing toward the liquid flow meters to the
bottom parts on the outside also in order to accomplish simultaneous
heating of the inner and outer layers of the bottom parts. However
that solution becomes relatively expensive and is not practically
feasible.
Various variations of the stiffening member and connecting member
are disclosed including various shapes of the bell-shaped stiffening
member and the inclusion of ribs for further stiffening.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of a preferred embodiment of the present
invention.
FIG. 2 is a cross-sectional elevation view of the embodiment of
FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Shown on FIG. 1 is the bottom part 1 of a flow meter, in this case
a rotary-piston flow meter. In such a flow meter, the measuring
means will rotate within a space 16 with an edge of the measuring
means sliding against a portion 17 of the bottom part 1. The problem
which arises without the arrangement of the present invention is
that a sudden inflow of hot liquid can cause an inward buckling
of the bottom member 1 resulting in seizing of the measuring means.
In the illustrated embodiment of the present invention the bottom
part 1 is strongly connected at its edges 2 to a bell-shaped stiffening
element, preferrably by welding using a weld 2a. Approximately in
the center of the bell-shaped stiffening element 3 a rigid connecting
member 4 is welded thereto. This connecting member 4 along with
the journal 5 of the rotary-piston meter forms a pin 6 which is
brought through an opening 7 in the bottom part 1. It is welded
to the bottom part with a weld 7a resulting in a firm mechanically
connection and a sealing action. The basic requirement for the connecting
member 4 is that a connection between the bottom 1 and the stiffening
element 3 be established. In the illustrated embodiment this is
done in a particularly advantageous manner by combinding the function
of journal 5 and stiffening element 4. However such is not necessarily
a limitation of the invention. Other arrangements are also possible.
Where particularly unfavorable conditions of buckling are anticipated,
several connecting members such as connecting member 4 may be used.
These may be installed between the bottom part and the bell-shaped
stiffening member and distributed over the bottom part rather than
having one rigid connecting member engaging the central region of
the bottom part. This is illustrated by the rigid connecting members
4a shown in dotted lines.
FIGS. 1 and 2 also illustrates a further provision which more completly
prevents buckling of the bottom parts. Thus, there are shown support
ribs 8 through 15 which are welded at the edge 2 to the bottom part
along with being welded to the bell-shaped stiffening element 3
and the rigid connecting member 4. The ribs 8 through 15 are attached
in a manner such that, due to the appropriately chosen shape of
the bottom part 1 they do not rest closely against the surface
thereof. The ribs have an external shape corresponding to the inner
contours of the bell-shaped stiffening member as shown. They may
be installed radially as illustrated or may be attached as cords
inside the bell-shaped stiffening element 3. It is particularly
advantageous that the support ribs be connected to a support element
attached to the center of the bell-shaped stiffening element. In
the illustrated embodiment they are thus attached to the rigid connecting
member is the support element to which the support ribs are attached.
It is also possible to provide a tube section surrounding the connecting
member 4 for use as a support element if such ficilitates the manufacture
and assembly.
The bell-shaped stiffening element 3 may have the shape of spherical
segment, preferably a hemisphere. Furthermore it may also have the
form of a compound curve or be a domed head. Shapes such as this
are well known in the art from the design of boilers and other vessels.
As indicated above the illustrated embodiment is particularly advantageous
where the measuring means is a rotary-piston guided in a ring chamber
such as the chamber 16 and which has a journal 5 therein as described
above. In that case an extension of the journal 5 forms the connecting
member 4 with the connecting member 4 firmly attached to the bottom
and to the bell-shaped stiffening element. With this design the
connecting member is not an additional element but can be made in
a single piece with the measuring chamber journal in a single machining
operation.
Thus a liquid flow meter which operates in a trouble free manner
even when liquids with relatively high temperatures are suddenly
fed thereto has been shown. Although specific embodiments have been
illustrated and described, it will be obvious to those skilled in
the art that various modifications may be made without departing
from the spirit of the invention which is intended to be limited
solely by the appended claims. |