Measuring and testing – Volume or rate of flow – Mass flow by imparting angular or transverse momentum to the...
Reexamination Certificate
2001-04-11
2004-03-30
Lefkowitz, Edward (Department: 2855)
Measuring and testing
Volume or rate of flow
Mass flow by imparting angular or transverse momentum to the...
Reexamination Certificate
active
06711958
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to a mass flow rate/density/viscosity sensor working on the Coriolis principle—herein-after referred to as a Coriolis sensor for short—and comprising two bent measuring tubes.
With such Coriolis sensors, whose measuring tubes, as is well known, are set into vibration, particularly into flexural vibration with or without superposed torsional vibration, it is possible to measure not only the instantaneous mass flow rate of a fluid flowing in a pipe, but also the density of the fluid via the instantaneous vibration frequency of the measuring tubes and the viscosity of the fluid via the power required to maintain the vibrations of the tubes.
Since the temperature of the fluid is not constant during operation of the Coriolis sensor, and the density of the fluid, as is well known, is temperature-dependent, the Coriolis sensor is commonly provided with at least one temperature sensor for measuring the temperature of the fluid. For all those measurements, the Coriolis sensor is connected into the pipe in a pressure-tight manner and generally permanently, for example via flanges.
U.S. Pat. No. 4,187,721 discloses a Coriolis mass flow rate/density sensor designed to be installed in a pipe through which a fluid flows at least temporarily, and comprising:
a single, U-shaped measuring tube bent in one plane symmetrically with respect to an axis of symmetry, which
is of one-piece construction and
has a straight inlet portion fixed in a support angle,
a straight outlet portion fixed in the support angle,
an offset inlet transition portion connected with the inlet portion,
an offset outlet transition portion connected with the outlet portion,
a first bent portion connected with the inlet transition portion,
a second bent portion connected with the outlet transition portion,
a straight base portion connecting the first and second bent portions;
an excitation system
which in operation causes the measuring tube together with an exciter carrier to vibrate as a tuning fork,
a first portion of which is fixed to the base portion in the area of the axis of symmetry, and
a second portion of which is fixed to the exciter carrier;
a first optical sensor,
a first portion of which is fixed to the measuring tube at a location
where the inlet transition portion passes into the first bent portion, and
a second portion of which is fixed to the support angle; and
a second optical sensor,
a first portion of which is fixed to the measuring tube at a location
where the outlet transition portion passes into the second bent portion, and
a second portion of which is fixed to the support angle.
JP-A 56-125 622 discloses a Coriolis mass flow rate sensor designed to be installed in a pipe through which a fluid flows at least temporarily, and comprising:
an omega-shaped measuring tube bent in one plane symmetrically with respect to an axis of symmetry which
is of one-piece construction and
has a straight inlet portion with an inlet axis lying in said plane,
a straight outlet portion with an outlet axis aligned with the inlet axis,
an S-shaped inlet bend connected with the inlet portion,
an S-shaped outlet bend connected with the outlet portion, and
a vertex bend connecting the inlet and outlet bends;
an excitation system
which in operation causes the measuring tube together with an exciter carrier to vibrate as a tuning fork,
a first portion of which is fixed to the vertex bend in the area of the axis of synunetry, and
a second portion of which is fixed to the exciter carrier;
a bar-shaped sensor carrier
which extends perpendicular to the axis of symmetry,
a first end of which is fixed to the measuring tube at a location where the inlet bend passes into the vertex bend, and
a second end of which is fixed to the measuring tube at a location where the outlet bend passes into the vertex bend; and
a strain-gage bridge disposed as a sensor arrangement on the sensor carrier.
U.S. Pat. No. 4,127,028 discloses a Coriolis mass flow rate sensor designed to be installed in a pipe through which a fluid flows at least temporarily, and comprising:
a first U-shaped measuring tube bent in a first plane symmetrically with respect to a first axis of symmetry;
a second U-shaped measuring tube bent in a second plane symmetrically with respect to a second axis of syimnetry,
which measuring tubes are arranged parallel to each other, are of one-piece construction, and are connected in series in terms of fluid flow, and
each of which measuring tubes has
a straight inlet portion,
a straight outlet portion,
an S-shaped inlet bend connected with the inlet portion,
an S-shaped outlet bend connected with the outlet portion,
a first straight tube portion connected with the inlet bend,
a second straight tube portion connected with the outlet bend, and
a semicircular base bend connected with the first and second straight tube portions,
which inlet and outlet portions extend through a fixed member,
with the distance between the inlet and outlet portions of each measuring tube being less than the distance between the first and second straight tube portions of the respective measuring tube;
an excitation system
which during operation causes the measuring tubes to vibrate as a tuning fork,
a first portion of which is fixed to the semicircular base bend of the first measuring tube in the area of the axis of symmetry of the first measuring tube, and
a second portion of which is fixed to the semicircular base bend of the second measuring tube in the area of the axis of symmetry of the second measuring tube;
a first optical sensor,
a first portion of which is fixed to the first measuring tube and a second portion of which is fixed to the second measuring tube at respective locations
where the respective first straight tube portion passes into the respective semicircular base bend; and
a second optical sensor,
a first portion of which is fixed to the first measuring tube and a second portion of which is fixed to the second measuring tube at respective locations
where the respective second straight tube portion passes into the respective semicircular base bend.
U.S. Pat. No. 4,622,858 discloses a Coriolis mass flow rate sensor designed to be installed in a pipe through which a fluid flows at least temporarily, and comprising:
a first straight measuring tube;
a second straight measuring tube,
which measuring tubes are arranged parallel to each other,
are of one-piece construction, and
are connected in parallel in terms of fluid flow by means of an inlet manifold and an outlet manifold;
a driving mechanism
which in operation vibrates the measuring tubes as a tuning fork,
a first portion of which is fixed to the first measuring tube midway between the inlet manifold and the outlet manifold, and
a second portion of which is fixed to the second measuring tube midway between the inlet manifold and the outlet manifold;
a first electrodynamic sensor,
a first portion of which is fixed to the first measuring tube midway between the driving mechanism and the inlet manifold, and a second portion of which is fixed to the second measuring tube midway between the driving mechanism and the inlet manifold; and
a second electrodynamic sensor,
a first portion of which is fixed to the first measuring tube midway between the driving mechanism and the outlet manifold, and a second portion of which is fixed to the second measuring tube midway between the driving mechanism and the outlet manifold.
U.S. Pat. No. 6,006,609 discloses a Coriolis mass flow rate/density/viscosity sensor designed to be installed in a pipe through which a fluid flows at least temporarily, and comprising:
a single straight measuring tube of one-piece construction
which is provided with a cantilever at its midpoint, and
an inlet end and an outlet end of which are mounted in a support frame which is disposed in a housing;
an excitation arrangement
which in operation sets the measuring tube into flexural vibrations and into torsional vibrations equal in frequency to the flexural vibrations, and
first portions of which are fixed to the cantilever and
Bitto Ennio
Koudal Ole
Schütze Christian
Bose McKinney & Evans LLP
Endress + Hauser Flowtec AG
Lefkowitz Edward
Thompson Jewel
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