Measurement sensor of the vibrational type for measuring the density and/or the mass flow of a flowing medium

A measurement sensor of the vibrational type for measuring the density and/or mass flow of a medium, the sensor comprising:

• a first oscillator, including:
• a first measuring tube having a first measuring tube center line extending in mirror symmetry relative to a measuring tube transverse plane, the first measuring tube configured to oscillate in a first bending vibration mode in mirror symmetry relative to the first measuring tube transverse plane, wherein the first measuring tube is bent in a rest position,
• wherein a first measuring tube longitudinal plane is defined in which the integral over the square of a distance between the first measuring tube center line and the first measuring tube longitudinal plane is minimal, and wherein the first measuring tube in the first bending vibration mode oscillates substantially perpendicularly to the first measuring tube longitudinal plane;
• a second measuring tube having a second measuring tube center line extending in mirror symmetry relative to the measuring tube transverse plane, the second measuring tube configured to oscillate in the first bending vibration mode in mirror symmetry relative to the first measuring tube transverse plane, wherein the first measuring tube and the second measuring tube are bent in the same direction in the rest position,
• wherein a second measuring tube longitudinal plane is defined in which the integral over the square of a distance between the second measuring tube center line and the second measuring tube longitudinal plane is minimal, and wherein the second measuring tube in the first bending vibration mode oscillates substantially perpendicularly to the second measuring tube longitudinal plane;
• and
• a first resilient vibration coupler adapted to couple the first measuring tube and the second measuring tube together;
• a second oscillator, including:
• a third measuring tube having a third measuring tube center line extending in mirror symmetry relative to the measuring tube transverse plane, the third measuring tube configured to oscillate in the first bending vibration mode in mirror symmetry relative to the measuring tube transverse plane, wherein the third measuring tube is bent in the rest position,
• wherein a third measuring tube longitudinal plane is defined in which the integral over the square of a distance between the third measuring tube center line and the third measuring tube longitudinal plane is minimal, and wherein the third measuring tube in the first bending vibration mode oscillates substantially perpendicularly to the third measuring tube longitudinal plane;
• a fourth measuring tube having a fourth measuring tube center line extending in mirror symmetry relative to the measuring tube transverse plane, the fourth measuring tube configured to oscillate in the first bending vibration mode in mirror symmetry relative to the measuring tube transverse plane, wherein the third measuring tube and the fourth measuring tube are bent in the same direction in the rest position,
• wherein a fourth measuring tube longitudinal plane is defined in which the integral over the square of a distance between the fourth measuring tube center line and the fourth measuring tube longitudinal plane is minimal, wherein the fourth measuring tube oscillates in the first bending vibration mode substantially perpendicularly to the fourth measuring tube longitudinal plane;
• and
• a second resilient vibration coupler adapted to couple the third measuring tube and the fourth measuring tube together;
• at least one exciter;
• and
• at least two vibration sensors, wherein:
• the measurement sensor has a measurement sensor longitudinal plane extending perpendicularly to the measuring tube transverse plane, wherein the first measuring tube center line extends in mirror symmetry relative to the third measuring tube center line with respect to the measurement sensor longitudinal plane, wherein the second measuring tube center line extends in mirror symmetry relative to the fourth measuring tube center line with respect to the measurement sensor longitudinal plane, wherein the measurement sensor longitudinal plane extends between the first measuring tube and the second measuring tube, wherein the measurement sensor longitudinal plane extends between the third measuring tube and the fourth measuring tube;
• the at least one exciter is configured to excite oscillator vibrations of the first oscillator and second oscillator with respect to one another;
• the measurement sensor has a first natural frequency for a vibration mode in which the first and second measuring tubes of the first oscillator oscillate approximately in phase with each other in the first bending vibration mode and in which the third and fourth measuring tubes of the second oscillator oscillate approximately in phase with each other in the first bending vibration mode;
• the measurement sensor has a second natural frequency for a vibration mode in which the first and second measuring tubes of the first oscillator oscillate approximately in phase opposition and in which the third and fourth measuring tubes of the second oscillator oscillate approximately in phase opposition in the first bending vibration mode;
• and
• the second natural frequency is greater than the first natural frequency.