Abstrict In a flow meter that works on the Coriolis principle there is provided
a single tube that is bent to have two measuring loops. Upper and
lower tube attachment end portions are respectively connected through
resilient tubular portions to the opposite ends of the two loops
and may be part of the single tube. The loops are superposed and
from the juncture of the loops and through at least parts of the
attachment end portions are of a continuous downward gradient such
that the fluid column in the flow meter will divide and drain through
the attachment end portions. Two blocks have tube holder portions
for retaining the loop first ends and the measuring loops opposite
ends in vertical spaced relationship and connecting the attachment
end portions together. The measuring loops are oscilatable in opposite
directions while sensors are provided adjacent to the measuring
loops for measuring the relative movement of the loops relative
to one another to provide a measurement of the fluid flow through
the loops.
Claims We claim:
1. A flow meter working on the Coriolis principle, comprising a
tubular upstream attachment end portion, a tubular downstream attachment
end portion, a tube having a first measuring loop that has a first
end and an opposite end, and a second measuring loop having a first
end and an opposite end, and a second measuring loop having a first
end and an opposite end joined to the first loop opposite end, first
tubular means for joining the upstream end portion to the first
loop first end, second tubular means for joining the second loop
first end to the downstream end portion, the measuring loops having
several bends and one loop above the other to have a continuous
gradient in a downward direction from the first loop first end to
the first loop opposite end and the second loop from the first loop
opposite end to the second loop first end, and being oscillatable
in the opposite sense relative to one another, sensor means located
adjacent to the measuring loops for providing a measurement that
depends on motion of the measuring loops that are being oscillated,
oscillator means adjacent to the measuring loops for oscillating
the loops in the opposite sense relative to one another, and attachment
means for connecting the upstream and downstream attachment end
portions to one another, and the first end second loops to one another
while permitting the loops being oscillated relative to one another,
each of the attachment end portions having a first end remote from
their juncture with the respective tubular means, the upstream attachment
end portion and the first tubular means being of a continuous downward
gradient from the first loop first end to the upstream attachment
end portion end, and the downstream attachment end portion and the
second tubular means being of a continuous downward gradient from
the second loop first end to the downstream attachment end portion
end.
2. A flow meter according to claim 1 characterized in that the
measuring loops are joined to one another in series.
3. A flow meter working on the Coriolis principle, comprising a
tubular upstream attachment end portion, a tubular downstream attachment
end portion, a tube having a first measuring loop that has a first
end and an opposite end, and a second measuring loop having a first
end and an opposite end joined to the first loop opposite end, first
tubular means for joining the upstream end portion to the first
loop first end, second tubular means for joining the second loop
first end to the downstream end portion, the measuring loops having
several bends and the first loop above the other to have a continuous
gradient in a downward direction from the first loop first end to
the first loop opposite end and the second loop from the first loop
opposite end to the second loop first end, and being oscillatable,
oscillator means adjacent to the measuring loops for oscillating
them in the opposite sense relative to one another, sensor means
located adjacent to the measuring loops for providing a measurement
that depends on motion of the measuring loops when being oscillated,
and attachment means for connecting the upstream and downstream
attachment end portions to one another, and the first and second
loops to one another while permitting the loops being oscillated
relative to one another, the attachment means including a first
block having three superposed tube holder portions for retaining
the first ends and the juncture of the opposite ends of the loops
in fixed relationship.
4. A flow meter working on the Coriolis principle comprising, a
tubular upstream attachment end portion, a tubular downstream attachment
end portion, the attachment portions having straight sections, a
tube having a first measuring loop that has a first end and an opposite
end, and a second measuring loop having a first end and an opposite
end joined to the first loop opposite end, first tubular means for
joining the upstream end portion to the first loop first end, second
tubular means for joining the second loop first end to the downstream
end portion, the measuring loops having several bends and the first
loop above the other to have a continuous gradient in a downward
direction form the first loop first end to the first loop opposite
end and the second loop from the first loop opposite end to the
second loop first end, and being oscillatable, the measuring loops
consisting of straight tube sections that in vertical projection
are substantially parallel to each other and the respective attachment
portion straight section, the bends extending through 180 degrees
and interconnecting the loop straight sections, there being at least
three loop straight sections, oscillator means adjacent to the measuring
loops for oscillating the loops in the opposite sense relative to
one another, sensor means located adjacent to the measuring loops
for providing a measurement that depends on motion of the measuring
loops when being oscillated, and attachment means for connecting
the upstream and downstream attachment end portions to one another,
and the first and second loops to one another while permitting the
loops being oscillated relative to one another, the attachment means
including a block at least partially disposed in the loops and connected
to three loop straight sections for retaining the three straight
loops in superposed vertical relationship.
5. A flow meter working on the Coriolis principle, comprising a
tubular upstream attachment end portion, a tubular downstream attachment
end portion, a tube having a first measuring loop that has a first
end and an opposite end, and a second measuring loop having a first
end and an opposite end joined to the first loop opposite end, first
tubular means for joining the upstream end portion to the first
loop first end, second tubular means for joining the second loop
first end to the downstream end portion, the measuring loops having
several bends and the first loop above the other to have a continuous
gradient in a downward direction form the first loop first end to
the first loop opposite end and the second loop from the first loop
opposite end to the second loop first end, and being oscillatable,
oscillator means adjacent to the measuring loops for oscillating
them in the opposite sense relative to one another, sensor means
located adjacent to the measuring loops for providing a measurement
that depends on motion of the measuring loops when being oscillated,
and attachment means for connecting the upstream and downstream
attachment end portions to one another, and the first and second
loops to one another while permitting the loops being oscillated
relative to one another, the loops, the tubular means and the attachment
portions being formed from a single tube that has several of the
bends and has straight tube sections supported by the attachment
means, the attachment means including segmented tube holders for
holding at least some of the tube sections.
6. A flow meter according to claim 1 characterized in that the
segmented tube holders comprises a first block connecting the attachment
end portions and a second block, that each of the tubular means
includes a resilient connecting tube portion that extends between
the blocks and has an end connected to the respective loop first
end, the second block having three superposed straight and parallel
tube holder portions for retaining the loop first ends and the juncture
of the opposite ends of the loops in fixed vertical relationship.
7. A flow meter according to claim 6 characterized in that the
second block has a lower end and that the first block is disposed
at the lower end of the second block and has opposite end faces
with the attachment end portions extending away therefrom, a side
face having a lower connecting tube portion extending away therefrom
and a top face having an upper tube portion extending away therefrom,
the lower and the upper tube portions constituting at least part
of the resilient connecting tube portions.
Description The invention relates to a flow meter working on the Coriolis principle
comprising an attachment apparatus connected on the one side to
an upstream and a downstream attachment tube and on the other side
to adjacent measuring tube loops which can be oscillated in opposite
senses by an oscillator and are provided with sensors for receiving
a measurement depending on the relative movement
Equipment of this kind is known, for example, from DE-AS 28 22
087 (corresponds to U.S. Pat. No. 4127028) or EP-OS 239 679. The
measuring tube loops are disposed in two parallel planes which are
either superposed or juxtaposed.
If one wishes to send different media through the meter in succession,
one encounters the difficulty on change-over that the old medium
will mix with the new medium. This can lead to disruptive reactions,
precipitation and the like.
The invention is based on the problem of providing a meter of the
aforementioned kind that can be completely emptied to avoid such
mixing.
This problem is solved according to the invention in that the measuring
tube loops are superposed and that a continuous gradient is provided
from one end of each loop to the other.
By reason of the fact that there is a continuous gradient within
each measuring tube loop, the loop can be easily emptied. It is
merely necessary to provide the lower end with a discharge. Subsequently,
the new medium can be introduced without mixing with the old medium.
It is desirable for the superposed measuring loops to be connected
in series. One will then have a continuous gradient over both loops.
Preferably, there are two gradient sections leading from a point
of maximum height to one of the two attachment ends. If both attachment
ends are provided with a discharge, the fluid column divides substantially
in the region of maximum height and emptying takes place to both
sides.
It is of particular advantage for the measuring tubes and the attachment
tubes to be formed by a single tube which is bent several times
and of which given sections are secured to the attachment apparatus.
Such a single tube simplifies production and assembly It has the
same cross-section throughout and forms no pockets in which dirt
can collect. Further, in contrast with assembled tube sections,
it is not necessary to take precautions about sealing the tube section
ends.
It is advisable for the attachment apparatus to comprise segmented
tube holders for receiving the given single tube sections The single
tube sections are simply inserted in one part of the tube holder.
The other part Is then placed above it and the two parts are interconnected,
which can be done by welding, soldering, adhesion, screws or even
a friction connection, depending on the nature of the material
Advantageously, the ends of the two measuring tubes are fixed in
three superposed tube holders. This simple feature deforms the measuring
tube loops spirally to produce the desired throughgoing gradient.
In one preferred embodiment, the attachment apparatus comprises
a first block connected to the attachment tubes, a second block
connected to the measuring tube loops, and at least one pair of
resilient connecting tubes between the two blocks, the second block
comprising three superposed and parallel tube holders which receive
the ends of the measuring tube loops and the connecting tubes. The
use of the connecting tubes keeps external influences such as clamping
forces or torques, vibrations and the like away from the second
block and the measuring tube loops secured therein. This leads to
a high measuring accuracy. In addition, the blocks can be comparatively
light in weight so that they will rapidly follow temperature changes
in the fluid. In connection with single tube clamping, the length
of the tube holders can be kept extremely short so that the changes
in length of the second block occuring through temperature changes
are negligible.
In particular, the first block may be disposed at the lower end
of the second block and be provided with the attachment tubes at
its opposed end faces, with a lower connecting tube at one side
face, and with an upper connecting tube at its top. This results
in a compact construction with a short rising tube.
From a constructional point of view, it is advisable that the measuring
tube loops should consist of straight tube sections substantially
parallel in the vertical projection to each other and to the attachment
tubes, which sections are interconnected by 180.degree. bends, and
that the first block should lie within the loop projection. This
results in an elongate meter requiring a comparative small cross-sectional
space and therefore being adapted for building into a protective
tube. The construction with straight tube sections is likewise very
simple when making from a single tube because only few bends have
to be provided.
A preferred example of the invention will now be described in more
detail with reference to the drawing wherein:
FIG. 1 is a perspective view of a flow meter according to the invention,
and
FIG. 2 is a side elevation with diagrammatically illustrated other
parts
The illustrated flow meter has an upstream attachment tube 1 and
a downstream attachment tube 2 which could be provided with a flange
and lead from outer attachment ends 1a and 2a to opposite ends of
a first block 3. The latter is connected to a second block 6 by
way of two resilient connecting tubes 4 and 5. The second block
has two superposed measuring tube loops 7 and 8 secured to it. These
each consist of three straight tube sections 9 10 and 11 or 12
13 and 14 and two 180.degree. bends 15 and 16 17 and 18. As shown
in FIG. 2 there is a continuous gradient to both sides of the highest
point S.
The entire tube formation is bent from a single tube R and is held
in the correct position by the two blocks 3 and 6. For this purpose,
the block 3 forms two tube holders 19 and 20 whilst the block 6
forms three tube holders 21 22 and 23. The latter consist of three
parallel apertures whilst the former have a curved configuration.
To enable the appropriate tube sections to be inserted in the tube
holders, the block 3 consists of a rear portion 24 and a front portion
25 the separating line passing through the two tube holders 19
and 20. The block 6 consists of a rear portion 26 and a front portion
27 of which the separating line again goes through the three tube
holders 21 22 and 23. During production, the tube R is first bent.
The tube sections to be fixed are then one-sidedly placed in one
block portion. Thereupon the other block portion is laid over it
and the whole is interconnected.
In the middle of the sections 10 13 the two measuring tube loops
7 and 8 possess an oscillator 28 and near the ends of these tube
sections they have sensors 29 and 30 for determining a measurement
which depends on the oscillating movement.
To enable various media to be measured, the attachment tube 1 can
be connected by valves 31 32 and 33 to tubular conduits 34 35
and 36 respectively. A further valve 37 serves to connect to a
discharge 38 through which air can also enter. The attachment tube
2 is connected by way of a valve 39 to a discharge 40 through which
air can also enter and by way of three valves 41 42 and 43 to conduits
44 45 and 46 respectively.
It is assumed that the flow of a liquid is being measured that
is supplied through the conduit 34 and taken away through the conduit
44. To change to a different liquid, the valves 31 and 41 are first
closed and the valves 37 and 39 opened. Consequently, the meter
can be emptied through the discharges 38 and 40 the liquid column
being parted in the region of the highest point S. Thereafter, the
valves 37 and 39 are closed and the valves 32 and 42 opened. A different
liquid can now flow from the conduit 35 by way of the meter to the
conduit 45.
Naturally, this principle is also suitable for differently formed
measuring tube loops, for example loops bent into a circle or into
the shape of a tennis racket. Also, the loops need not extend to
both sides of a block. They could both be completely disposed on
one side of this block, as is known in the prior art. For emptying,
the valve can also be connected to a source of slight over-pressure.
For further details, attention is drawn to the applicants' applications
having the same title "Flow meter working on the Coriolis principle"
(I), (II) and (IV). |