Patent attributes
When outputs from two vibration detection sensors are measured by a Coriolis flowmeter in a form of phase difference time, a tube must be thinned to increase a sensitivity of the flowmeter to enable measurement and accordingly flow velocity and pressure loss increase, and a thickness of the flowmeter must be reduced and therefore a pressure resistance cannot be readily enhanced. In particular, the sensitivity of signals to flow rate is difficult to increase and, accordingly, a flow rate of a low-density gas cannot be accurately measured. In the present invention, a Coriolis vibration frame 16 carrying a U-shaped tube is swingably fixed to a forced vibration frame 19 fixed to a support base 22 to form a highly rigid frame structure limiting a vibrating direction to one degree of freedom in a Coriolis vibration direction. The forced vibration frame 19 is vibrated by a vibration exciter 20 so that a ratio of a forced vibration frequency to the Coriolis frequency of a pipeline is at least 1 to 10. The ratio of the amplitude of the forced vibration to the amplitude of the Coriolis vibration is calculated based on signals from two vibration sensors such as acceleration sensors 17 and 18 to measure the mass flow rate of a fluid flowing in the pipeline.
