Mass flow meter

A mass flow meter for flowing media that works on the Coriolis Principle includes at least one oscillating Coriolis line carrying the flowing medium and at least one housing holding the Coriolis line, and attachments to the housing. The mass flow meter is characterized by the fact that at least some of the attachments are connected to the housing via means of oscillation decoupling.

The invention concerns a mass flow meter for flowing media that works on 
the Coriolis Principle, with at least one oscillating Coriolis line 
carrying the flowing medium and at least one housing holding the Coriolis 
line and attachments to the housing. 
BACKGROUND OF THE INVENTION 
A large number of designs are known for mass flow meters for flowing media 
that work on the Coriolis Principle. The number of proposals for making 
the Coriolis line run optimally is almost impossible to review. For the 
flowing medium to bring about the desired Coriolis effect in the Coriolis 
line, the Coriolis line must be in oscillation. An oscillator, or 
frequently several oscillators, is generally used for this purpose. In 
conventional flow meters, the mass flow of the flowing medium through the 
Coriolis line is determined by quantitative analysis of the Coriolis force 
acting on the oscillating Coriolis line. Since the Coriolis forces that 
occur are generally very small, conventional flow meters are particularly 
sensitive to the output and input of mechanical energy between the mass 
flow meter and its environment. In the past, the mechanical coupling 
between the flow meter and the pipelines connected to the flow meter 
received a lot of attention, and a great many suggestions have been made 
for solutions that attempt to reduce this mechanical coupling. 
The coupling between the Coriolis line and the housing holding generally 
the Coriolis line, the oscillator or oscillators and the transducer or 
transducers that senses the motion of the Coriolis line has already been 
the subject of improvements as well. The common approach to this is to 
guarantee very strong decoupling between the Coriolis line and the housing 
by making the inherent frequency of the housing as different as possible 
from the oscillation frequency of the Coriolis line. To do so, the housing 
is generally designed to be very rigid to oscillation. 
In the past, no attention was paid to the problem of the mechanical 
coupling between the Coriolis line and the housing, on one hand, and the 
flow meter's various attachments to the housing, on the other. 
Frequently, a basic device, i.e., a unit consisting of the Coriolis line, 
an oscillator, a transducer and a housing, is used as the basis for a 
large number of mass flow meters for different purposes. Depending on the 
purpose for which the flow meter is used, various attachments are 
connected to the flow meter, respectively to its housing. Because these 
attachments are connected to the housing in a way that is generally 
undefined, mechanical couplings are created in systems capable of 
oscillation that can have a major influence on the measurement precision 
of the flow meter. These unwanted influences frequently cannot be 
prevented by the corresponding layout of the attachments, since the 
mechanical coupling is frequently also influenced by the specific on-site 
installation situation, whose design understandably cannot be considered. 
As a result, on the known flow meters, the influences determining the 
oscillation properties of the device cannot be determined in advance by a 
corresponding design, so that the measurement precision of the mass flow 
meter is already affected by inadequate definition of the whole mass flow 
meter as a system capable of oscillation. 
The object of the invention is thus based on improving the known mass flow 
meters for flowing media that work on the Coriolis Principle in such a way 
that the technical oscillation properties of the whole device remain 
basically constant regardless of the different attachments, so that high 
measurement precision is guaranteed. 
SUMMARY OF THE INVENTION 
The object already presented and described is solved according to the 
invention by having at least a part of the attachments connected to the 
housing via means of oscillation decoupling. The measure in the invention 
guarantees a defined oscillation behavior of the mass flow meter, since 
the undefined influences of the attachments have very little or no effect 
on the oscillation behavior as a whole. According to known physical laws, 
the means of oscillation decoupling are designed so that, if possible, 
there is no, or only slight, oscillation coupling between the attachments 
and the housing. 
Springs are especially good as means of oscillation decoupling for economic 
reasons. They are simple to make and synchronize and are available in a 
large number of forms of embodiment, adapted to the respective purpose for 
which they are used. 
Oscillation decoupling between the attachments and the housing is 
advantageous, particularly for large-sized attachments, like for example 
electronic evaluation units, attachments with an outer abutment, like for 
example cables or pipe-type cables, and attachments with particularly 
defined oscillation properties, like for example means for heating the 
mass flow meter. 
Now there are many different ways of designing and developing the mass flow 
meter according to the invention for flowing media that works on the 
Coriolis Principle. In this connection, please refer to the patent claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows a mass flow meter for flowing media that works on the Coriolis 
Principle. The schematic drawing shows only the housing 1 holding a 
Coriolis line C, an attachment 2, not further specified, and a means 3 of 
oscillation decoupling according to the invention which connects the 
housing 1 to the attachment 2. By choosing spring and damping properties 
of the means 3 of oscillation decoupling that are tailored to the housing 
1 and the attachment 2, the oscillation decoupling according to the 
invention between the housing 1 and the attachment 2 is guaranteed. 
FIG. 2 shows a special example of an embodiment of a mass flow meter for 
flowing media according to the invention that works on the Coriolis 
Principle. FIG. 2 shows only a cutout of this example of embodiment in 
cross section. A base 4 having a flange 4a is attached to the wall 1a of 
housing 1 via a solder connection 5. An attachment in the form of an 
electronic evaluation unit 6, shown only in section has a flange 6a that 
interfits with flange 4a forming a connection that allows relative 
movement of base 4 and electronic evaluation unit 6 only in the axial 
direction. A spring unit, shown generally at 7, forms a central element of 
this connection. Depending on the requirement, this spring unit 7 can be 
composed of one or more spring washers, one or more coil springs or one or 
more leaf springs. The spring unit 7 is thus designed to guarantee maximum 
oscillation decoupling of housing 1 and evaluation unit 6. 
The measure according to the invention justifies the expense connected with 
it only in a case where the attachment in question has a substantial 
influence on the measurement precision of the mass flow meter. It is, 
therefore, not always necessary to connect all attachments to the housing 
via means of oscillation decoupling. 
It will thus be seen that the objects set forth above, among those made 
apparent from the preceding description, are efficiently attained and, 
since certain changes may be made in the above construction without 
departing from the scope of the invention, it is intended that all matter 
contained in the above description or shown in the accompanying drawings 
shall be interpreted as illustrative and not in a limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention described 
herein.