Device for measuring the density of a fluid

Claim 3

A device according to claim 1 wherein said torsional oscillation means includes: a pair of drive coils located adjacent to said U-shaped portion such that the coil axes are perpendicular to the longitudinal axis of said U-tube; an amplifier; and vibration sensing means mounted on said base member and providing an output signal coupling to the input of said amplifier, the output of said amplifier being coupled to said pair of drive coils so as to cause said coils to maintain an alternating torsional couple with respect to the longitudinal axis of said U-tube.

Claim 4

A device according to claim 2 wherein said measuring means includes: a frequency meter the input of which is coupled to the output of said amplifier.

Claim 5

A device according to claim 3 and further including: a pair of magnetic ring members, each ring member being disposed around a respective leg portion of said U-tube and aligned with the axis of a respective one of said drive coils.

Claim 6

A device according to claim 4 and further including a permanent magnetic member disposed at the end of each drive coil and directed toward said U-tube.

Claim 7

Apparatus for measuring the density of a fluid comprising: two pair of base members; first and second tubular members, each comprising a U-shaped end portion having a pair of leg portions extending therefrom and mounted on a respective one of said base members, one of said tubular members providing for the passage of a fluid the density of which is to be measured; first and second amplifiers; two pairs of drive coils, each pair being positioned for operation in association with a respective pair of said leg portions, the outputs of said amplifiers being coupled to a respective one of said drive coil pairs, said coil pairs being spaced at equal distances from the base member securing the respective pair of leg portions so that each coil pair maintains an alternating torsional couple with respect to the median axis of the associated tubular member and imparts vibrational movements thereto; first and second vibration sensing means secured to a respective one of said base members, said sensing means each providing an output signal indicative of the frequency of oscillation of said respective tubular member for coupling to an input of a respective one of said first and second amplifiers; mixing means responsive to said first and second amplifier means for providing a signal corresponding to the difference in frequency of oscillation of said tubular members; and a frequency meter coupled to the output of said mixing means for providing a measurement of said difference frequency, said difference frequency being representative of the density of the fluid to be measured, each of said tubular member structures being arranged relative to one another such that they are under the influence of the same temperature conditions.

Claim 8

Apparatus for measuring the density of a fluid comprising: two pair of base members; first and second tubular members, each comprising a U-shaped end portion having a pair of leg portions extending therefrom and mounted on a respective one of said base members, one of said tubular members providing for the passage of a fluid the density of which is to be measured; first and second amplifiers; two pairs of drive coils, each pair being positioned for operation in association with a respective pair of said leg portions, the outputs of said amplifiers being coupled to a respective one of said drive coil pairs, said coil pairs being spaced at equal distances from the base member securing the respective pair of leg portions so that each coil pair maintains an alternating torsional couple with respect to the median axis of the associated tubular member and imparts vibrational movements thereto; first and second vibration sensing means secured to a respective one of said base members, said sensing means each providing an output signal indicative of the frequency of oscillation of said respective tubular member for coupling to an input of a respective one of said first and second amplifiers; mixing means responsive to said first and second amplifier means for providing a signal corresponding to the difference in frequency of oscillation of said tubular members; and a frequency meter coupled to the output of said mixing means for providing a measurement of said difference frequency, said difference frequency being representative of the density of the fluid to be measured, each of said tubular member structures being arranged relative to one another such that they are under the influence of the same temperature conditions.