A flow meter, particularly for warm water heating systems, includes
a measuring element and an indicator element. The indicator element
has a basic component with a cylindrical attachment extending into
the collector pipe. An indicator rod with a rebounding plate extends
into the measuring element and vertically slidable. According to
the invention, a filter is installed ahead of the rebounding plate
in the flow direction of the heating medium. Where the basic component
extends to a cylindrical attachment affecting the flow against the
rebounding plate, it is suitable to provide a number of slits in
the cylindrical external wall of the lower portion of the attachment,
the slits being distributed around the perimeter parallel to the
axis. In this manner, dirt particles, which could impair the function
of the indicator, are virtually filtered out.
What is claimed is:
1. A flow meter comprising: a measuring element for measuring a
flow of a medium; and an indicator element for indicating a flow
of the medium, wherein the indicator element includes a basic component
having a cylindrical portion extending into a distribution pipe
through which an indicator rod having a rebounding plate extends
into the measuring element and is vertically movable therein, and
wherein a filter is provided upstream of the rebounding plate in
the flow direction of the medium.
2. The flow meter according to claim 1 wherein the basic component
extends into a cylindrical attachment that influences the flow towards
the rebounding plate, and wherein a lower portion of the cylindrical
attachment is designed as the filter.
3. The flow meter according to claim 2 wherein the lower portion
of the cylindrical attachment is provided with a plurality of slits
that are distributed around a circumference of the lower portion
and are parallel to an axis formed by the flow direction of the
medium through the measuring element.
4. The flow meter according to claim 3 wherein the slits are evenly
distributed around the circumference of the lower portion of the
5. The flow meter according to claim 3 wherein a width of the
slits increases in the direction of the flow.
6. The flow meter according to claim 3 wherein at a point of entry
of the medium, the slits have a width of 0.5 to 1.0 mm.
7. The flow meter according to claim 6 wherein the slits have
a width of 0.8 mm.
8. The flow meter according to claim 2 wherein the lower portion
of the attachment is designed as an insert, which is connectable
to the attachment by insertion into the cylindrical attachment.
9. The flow meter according to claim 8 wherein the indicator rod
is guided in the insert vertically slidable.
10. The flow meter according to claim 2 wherein the lower portion
is made of plastic.
11. The flow meter according to claim 1 wherein the flow meter
is used for warm water heating systems.
12. The flow meter according to claim 1 wherein the filter is
between the indicator element and the measuring element.
13. A flow meter comprising: an indicator element for indicating
a flow rate of a medium through the flow meter via a rebounding
plate that is slidably attached to the indicator element; a measuring
element having a measuring bore extending along an axis, the axis
being substantially parallel to a flow direction of the medium,
the rebounding plate slidably extending into the measuring bore
of the measuring element; and a cylindrical attachment being provided
between the indicator element and the measuring element, the cylindrical
attachment having an internal bore for enabling the rebounding plate
to extend slidably therethrough from the indicator element to the
measuring element, the internal bore of the cylindrical attachment
having a diameter that is adapted to fixedly receive an insert,
the insert having a plurality of apertures provided therein for
filtering dirt particles from the medium.
14. The flow meter according to claim 13 wherein the apertures
that are provided in the insert for filtering dirt particles from
the medium have a greater width on an inner circumference of the
insert than on an outer circumference of the insert.
15. The flow meter according to claim 13 wherein a mesh screen
is provided to substantially cover a medium entrance of the apertures,
which are provided on the insert.
16. The flow meter according to claim 13 wherein the insert has
two apertures on a circumferential side of the insert.
17. The flow meter according to claim 16 wherein the two apertures
are substantially across from one another on the circumferential
side of the insert.
18. The flow meter according to claim 13 wherein the flow meter
is a forward-flow flow meter.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flow meter, particularly for
warm water heating systems.
2. Description of the Background Art
Flow meters of this type for flowing liquids are generally known.
They are frequently used in warm water heating systems to register
partial flows of a heating medium in various pipe lines, or branch
lines, and to be able to monitor them during operation. Flow meters
of this kind have an indicator scale, of which the respective position
of an indicator rod, having a rebounding plate that is influenced
by the flowing medium, can be read. Conventionally, the indicator
scale is usually arranged on a surface of an inspection glass along
In a conventional flow meter of this type, for example, as described
in EP 0 884 514 B1 the indicator element as well as the measuring
element are screwed opposite of each other with cylindrical attachments
into a collector pipe, whereby a gap is formed between the lower
end of the indicator element and the upper end of the measuring
element. If such a flow meter is not used in the return flow, as
taught in EP 0 884 514 B1 where the rebounding plate of the indicator
rod is slidable in the internal bore of the measuring element and
is exposed to direct flow, but is used in the forward flow, then
it is necessary to influence the flow against the rebounding plate
in order to avoid any turbulence of the flow against the rebounding
plate. This is accomplished, for example, by arranging a pipe-shaped
attachment in the area between the lower end of the indicator element
and the upper end of the measuring element, which bridges this gap
for the most part and is provided with openings, which influence
It was found in actual operation that in warm water heating systems,
particularly after operation of the system was started or after
the system was serviced, sharp-edged dirt particles are often transported
with the heating medium. Since the annular gap between the outer
perimeter of the rebounding plate and the internal bore of the measuring
element is, for flow-technical reasons, very narrow, the danger
exists that such dirt particles can get jammed or clogged in this
annular gap, thereby blocking the function of the indicator.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a
flow meter that avoids an impairment of the measuring process by
dirt particles without disturbing the steady flow against the rebounding
The invention is based on the idea to install a filter ahead, e.g.,
upstream, of the rebounding plate in the flow direction of the heating
medium to filter out dirt particles that could impair the function
of the indicator. It is advantageous, for practical purposes, to
design this filter in the form of longitudinal slits in the external
wall of the cylindrical attachment, which is an extension of the
cylindrical part of the basic component of the indicator element
extending in the direction of the measuring element.
It is considered particularly beneficial to design this attachment
as an insert, which can be made of metal or, in particular, of plastic,
and can be installed by insertion into the internal bore of the
cylindrical part of the basic component.
Further scope of applicability of the present invention will become
apparent from the detailed description given hereinafter. However,
it should be understood that the detailed description and specific
examples, while indicating preferred embodiments of the invention,
are given by way of illustration only, since various changes and
modifications within the spirit and scope of the invention will
become apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the
detailed description given hereinbelow and the accompanying drawings
which are given by way of illustration only, and thus, are not limitive
of the present invention, and wherein:
FIG. 1 is a partial cross-section of a side view of a flow meter
mounted on a collector pipe according to a preferred embodiment
of the invention;
FIG. 2 is a cross section through the flow meter along the line
II--II in FIG. 1;
FIGS. 3a-d show various illustrations of a basic component of an
indicator element of the flow meter;
FIG. 4 is an illustration of an alternate embodiment of the flow
meter of FIG. 1; and
FIG. 5 is a cross section through the flow meter along the line
V-V in FIG. 4.
The flow meter 1 which is illustrated in FIG. 1 including a measuring
element 2 and an indicator element 3 is mounted on a forward-flow
distribution pipe 4 of a warm water heating system and measures
the forward flow, in the direction of arrow 7 in an individual
branch line 5. It is common practice to arrange several such flow
meters next to one another on the distribution pipe 4 for various
The measuring element 2 which is tightly screwed into the distribution
pipe 4 by an external screw thread 6 has a connecting branch line
5 which is not actually illustrated but only indicated by the arrow
7 which is pointing in the flow direction. As is principally standard
practice, a rebounding plate 10 which is supported by an indicator
rod 9 is located in a measuring bore 8 of the measuring element
2. The measuring bore 8 is conically enlarged towards the branch
line 5 whereby the position of the rebounding plate 10 along the
measuring bore 8 depends on the respective flow-through.
The indicator element 3 is mounted opposite the measuring element
2 on top of the distribution pipe 4. The indicator element 3 includes
a basic component 11 that is tightly screwed together with the distribution
pipe 4 and has a tube-shaped inspection glass 12 that is made of,
for example, transparent material. The indicator rod 9 is guided
in the indicator element 3 so that it can slide vertically, e.g.,
in the flow direction, and has a disk-shaped pointer 13 close to
its upper end, which moves up and down in the bore of the inspection
glass 12 depending on the position of the rebounding plate 10.
Across from the bottom of the bore of the inspection glass 12 and
the pointer 13 that is, the indicator rod 9 a pressure spring
14 is supported. The scale for reading the respective flow quantity
is located in a sleeve-shaped scale carrier 15 which is arranged
around the inspection glass 12. The principle construction and function
of such a flow meter are known to those skilled in the art and do
not need to be described any further.
As can be seen in FIG. 1 the basic component 11 of the indicator
element 3 which is screwed into the distribution pipe 4 by an external
screw thread 16 extends within the cross section of the distribution
pipe 4 into a cylindrical attachment 17. The cylindrical attachment
17 features an internal bore, through which the indicator rod 9
is vertically slidable. According to the invention, a lower portion
18 of the cylindrical attachment 17 which has limited play towards
an upper front edge 19 of a connecting pipe 20 of the measuring
element 2 extending into the distribution pipe 4 is designed as
a filter. In the illustrated embodiment, the lower portion 18 has
a number of slits 21 extending parallel to an axis, e.g., the flow
direction, of the flow meter and are evenly distributed around the
perimeter of the attachment 18.
The distribution of the longitudinal slits 21 and the flow through
the lower portion 18 thus achieved is illustrated in FIG. 2 in a
cross section through the lower portion 18 along line II--II shown
in FIG. 1. It can also be seen here that the width of the longitudinal
slits increases in the direction of the flow, that is, from the
outside to the inside, to enforce the effectiveness of the filter
and to keep out potential dirt particles. A suitable size of the
longitudinal slits is approximately 0.8.times.6.0 mm so that particles
measuring less than 0.8 mm can potentially pass into the measuring
zone, which reduces the risk of blocking the Indicator rod considerably.
In FIG. 3 the basic component 11 of the indicator element 3 is
shown in several different illustrations. While FIG. 3a shows the
basic component 11--much like in FIG. 1--in (full) view and FIG.
3d in diagonal view, the insertion of the filter element into the
basic component is described with reference to FIGS. 3b and 3c.
The lower portion 18 of the cylindrical attachment 17 having the
longitudinal slits 21 is, for practical purposes, designed as an
insert, which can be inserted from below into an internal bore 22
of the cylindrical attachment 17 of the basic component 11. Thus,
the lower portion 18 can be made of materials, which can be different
from the material that the basic component 11 is made of, for example,
plastic of suitably robust consistency. On its outer perimeter,
the lower portion 18 can have a ring bulge 23 or protrusions that
are provided across from each other, and which pliably lock into
a groove when inserted into a lower area 22a of the internal bore
22 and thus assure firm engagement. It goes without saying that
other means of installation are possible, for example, screwing
(the insert) into position.
The lower portion 18 can also include a guide (not shown) for the
indicator rod 9 namely in a central bore 24. Among other things,
it makes sense for installation reasons to practically assemble
the complete indicator element 3 from below so that first the inspection
glass 12 including a suitable O-Ring seal is inserted into the internal
bore 22 of the cylindrical attachment 17 and by inserting the lower
portion 18 with the indicator rod 9 and the rebounding plate 10
the indicator element 3 is fixed into position.
From a flow-technical standpoint, designing the filter to be installed
ahead, e.g. upstream, of the rebounding plate as longitudinal slits
21 has the advantage that the flow is divided into individual flow
threads thus smoothing the turbulent flow so that the indicator
is calmer and, therefore, more precise. In this way, the filter
also has a noise-reducing effect.
In FIGS. 4 and 5 an alternate embodiment is illustrated, whereby
a lower portion 18a of the attachment 17 is designed as an insert
for the attachment, as described above. In this embodiment, the
filter is installed ahead of the rebounding plate 10 and is designed
as a close-meshed screen 25 encircling the lower portion 18a. The
lower portion 18a of this embodiment has openings 26 that are provided
on opposite sides of the lower portion 18a, with the heating medium
flowing in the direction of the arrows.
The invention being thus described, it will be obvious that the
same may be varied in many ways. Such variations are not to be regarded
as a departure from the spirit and scope of the invention, and all
such modifications as would be obvious to one skilled in the art
are to be included within the scope of the following claims.