Coriolis mass flow/density sensor with a single straight measuring tube
First Claim
1. A Coriolis mass flow/density sensor which can be installed in a pipe and through which a fluid to be measured flows during operation, comprising:
- a single straight measuring tube having a longitudinal axis, an inlet end, and an outlet end;
a support fixed to the inlet end and the outlet end,a longitudinal centroidal line of the support which is parallel to, but does not coincide with, the longitudinal axis of the measuring tube;
a cantileverwhich is fixed to the measuring tube midway between the inlet end and the outlet end, andwhich during operation causes the measuring tube to vibrate either in a first fundamental flexural mode or in a second fundamental flexural mode having a higher frequency than the first fundamental flexural mode;
an excitation arrangement for constantly exciting the measuring tube in the second fundamental flexural modewhich is disposed approximately midway between the inlet end and the outlet end; and
a first sensor for detecting the motions of the measuring tube on an inlet side and a second sensor for detecting the motions of the measuring tube on an outlet side, the first sensor being located between the middle of the measuring tube and the inlet end and the second sensor being located between the middle of the measuring tube and the outlet end, the first and second sensors being located at the same distance from the middle of the measuring tube.
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Accused Products
Abstract
This mass flow/density sensor (10), which can be installed in a pipe and through which a fluid to be measured flows during operation, is to be balanced over a wide density range, so that accurate measurements are possible. A single straight measuring tube (13) having a longitudinal axis (131) extends between its inlet end (11) and the outlet end (12) and is fixed to a support, e.g., a cylindrical tube (14, 14'"'"'). The support has a longitudinal centroidal line (141) which is parallel to, but does not coincide with, the longitudinal axis (131) of the measuring tube. A cantilever (15) is fixed to the measuring tube (13) midway between the inlet and outlet ends (11, 12) and in operation causes the measuring tube to vibrate either in a first fundamental flexural mode or in a second fundamental flexural mode having a higher frequency than this first mode. An excitation arrangement (16) disposed midway between the end pieces excites the measuring tube (13) in the second mode. Sensors (17, 18) for the motions of the measuring tube on the inlet and outlet side are positioned between the middle of the tube and the inlet and outlet ends, respectively. The support may be provided with a counterbalance. Because of the torsional vibrations exerted by the cantilever on the measuring tube, the sensor is also well suited for measuring the viscosity of the fluid.
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Citations
34 Claims
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1. A Coriolis mass flow/density sensor which can be installed in a pipe and through which a fluid to be measured flows during operation, comprising:
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a single straight measuring tube having a longitudinal axis, an inlet end, and an outlet end; a support fixed to the inlet end and the outlet end, a longitudinal centroidal line of the support which is parallel to, but does not coincide with, the longitudinal axis of the measuring tube; a cantilever which is fixed to the measuring tube midway between the inlet end and the outlet end, and which during operation causes the measuring tube to vibrate either in a first fundamental flexural mode or in a second fundamental flexural mode having a higher frequency than the first fundamental flexural mode; an excitation arrangement for constantly exciting the measuring tube in the second fundamental flexural mode which is disposed approximately midway between the inlet end and the outlet end; and a first sensor for detecting the motions of the measuring tube on an inlet side and a second sensor for detecting the motions of the measuring tube on an outlet side, the first sensor being located between the middle of the measuring tube and the inlet end and the second sensor being located between the middle of the measuring tube and the outlet end, the first and second sensors being located at the same distance from the middle of the measuring tube. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A Coriolis mass flow/density sensor which can be installed in a pipe and through which a fluid to be measured flows during operation, comprising:
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a single straight measuring tube having an inlet end and an outlet end; an inlet plate fixed at the inlet end and surrounding the measuring tube; an outlet plate fixed at the outlet end and surrounding the measuring tube; a first support plate fixed to the inlet plate and the outlet plate and extending parallel to the measuring tube; a second support plate fixed to the inlet plate and the outlet plate and extending parallel to the measuring tube diametrically opposite the first support plate; a cantilever which is fixed to the measuring tube midway between the inlet end and the outlet end, and which during operation causes the measuring tube to vibrate either in a first fundamental flexural mode or in a second fundamental flexural mode having a higher frequency than the first fundamental flexural mode; a longitudinal bar located opposite the cantilever and fixed to the first and second support plates, said longitudinal bar acting as a counterbalance; an excitation arrangement which constantly excites the measuring tube in the second fundamental flexural mode, and which is disposed approximately midway between the inlet end and the outlet end; and a first sensor for detecting the motions of the measuring tube on an inlet side and a second sensor for detecting the motions of the measuring tube on an outlet side, the first sensor being located between the middle of the measuring tube and the inlet end and the second sensor being located between the middle of the measuring tube and the outlet end, the first and second sensors being located at the same distance from the middle of the measuring tube. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification