Patent ID: 7506551

Claim:
A Coriolis flowmeter comprising: a casing resistant to bending and torsion; a stationary member fixed within said casing, said stationary member having a rectangular shape when viewed from above and being formed as a flat plate; a pair of block-shaped support portions mounted and fixed to said stationary member; a flow tube including a straight portion and a pair of leg portions, each of said leg portions being connected to a respective end of said straight portion and oriented in a vertical direction, said flow tube being supported by said pair of support portions at respective ends of said pair of leg portions where a flow port is located, said flow tube having a symmetrical shape with respect to a vertical first axis parallel to said pair of leg portions; a first drive device arranged at a center position of said straight portion of said flow tube so as to be located on said vertical first axis, said first drive device being operable to alternately drive said flow tube in a rotating direction around a horizontal second axis parallel to a horizontal axis connecting positions at which said support portions support said flow tube, said first drive device including one of a coil and a magnet on said flow tube and the other one of a magnet and a coil on said stationary member; a pair of vibration detecting sensors symmetrically mounted with respect to said first drive device, each of said vibration detecting sensors being located at a respective one of a right side and a left side of said first drive device to detect a phase difference proportional to Coriolis forces acting on said flow tube; and a pair of second drive devices symmetrically mounted with respect to said first drive device, each of said second drive devices being located at a respective one of said right side and said left side of said first drive device in a lateral row along said straight portion of said flow tube, said pair of second drive devices being operable to alternately drive said flow tube in the rotating direction in phase around said horizontal second axis, each of said second drive devices including one of a coil and a magnet on said flow tube and the other one of a magnet and a coil on said stationary member, said pair of second drive devices being driven in a reverse phase with respect to said first drive device so as to make a bending vibration with a vibration beam in a tertiary vibration mode.