Abstract: A flow tube composed of a bent tube having a shape symmetrical with respect to a first axis is supported at its both ends by support portions having an outlet and inlet respectively. A drive device for alternately driving the flow tube rotationally about a second axis connecting the positions where the flow tube is supported is disposed on the vertical axis of a Coriolis flowmeter. A Pair of second drive devices for alternately driving the flow tube rotationally is disposed at positions laterally symmetrical with respect to the drive device. The paired second drive devices are driven in phase; the drive device is driven with the opposite phase to those of the second drive devices. A pair of vibration detecting sensors is disposed between the drive device and one of the second drive device and between the drive device and the other respectively.

Abstract: A start tube section (27) of a first bent tube (31) has a first parallel subsection (27a) substantially parallel to a start tube section (28) of a second bent tube (32) or to a continuous section (35) between a return tube section (29) of the first bent tube (31) and the start tube section (28) of the second bent tube (32), a first bent subsection (27b) continuous with the first parallel subsection (27a), and a first start tube section body subsection (27c) extending gradually away from the start tube section (28) of the second bent tube (32) due to presence of the first bent subsection (27b).

Abstract: In order that a flow tube of a Coriolis flowmeter may be vibrated in a tertiary mode using one drive device, the drive device is arranged at an antinode in the center of tertiary mode vibration, and vibration detecting sensors are arranged at two antinodes other than the antinode in the center of tertiary mode vibration. Moreover, the displacement polarity of the drive device is opposite to that of the vibration detecting sensors so that the vibration phases of the flow tube are in a relation of mutually opposite phases. Furthermore, in a positive feedback loop of an excitation circuit portion for exciting tertiary mode vibration of the flow tube and the vibration detecting sensors , the excitation circuit portion is structured so that the relation between the displacement polarities where the vibration phases of the flow tube are opposite to one another is converted to the relation where the vibration phases of the flow tube are in phase.

Abstract: A first inlet portion, a second inlet portion, a first outlet portion, and a second outlet portion are fixed to a fixing member, and a connecting tube portion is provided between the first outlet portion and the second inlet portion. Further, the first inlet portion and the second inlet portion are fixed so as to be in a non-parallel state such that the distance between the two increases as they depart from the fixing member, and the first outlet portion and the second outlet portion are similarly arranged in a non-parallel state. The first and second inlet portions and the first and second outlet portions are fixed so as to be arranged symmetrically. Further, the first outlet portion, the second inlet portion, and the connecting tube portion are arranged such that their tube axes are in a straight line. Further, the distance between driven portions is made small.

Abstract: A purge type vortex flowmeter capable of accurately measuring a flow rate of fluid over a wide range by reliably detecting the number of vortexes produced. A purge type vortex flowmeter which comprises a vortex generator (2) mounted in a passage of fluid to be measured in a flow pipe (1), two conduits (4a, 4b) having pressure ports (3a, 3b) in both side surfaces of the vortex generator for communication with the outside thereof and a front conduit (4c) having a pressure port (3c) in the front surface of the vortex generator. Purge fluid from a purge supply source is fed by a purge introducing means through a tube (5), the conduits (4a, 4b) and the front conduit (4c) into a flow of fluid to be measured in the flow pipe. Purge streams alternatively fluctuating by the effect of a difference from a fluctuating vortex pressure are discharged from the conduits (4a, 4b) through their pressure ports (3a, 3b).

Abstract: The Coriolis mass flow meter of this invention comprises two parallel curved flow tubes 1 and 2, a drive unit 15, and a pair of vibration sensors 16 and 17. An inlet-side manifold 24 dividing the flow of a fluid being measured into the two flow tubes 1 and 2 from the inlet thereof, and an outlet-side manifold 25 joining the fluid flows flowing in the two flow tubes 1 and 2 to discharge from the fluid outlet thereof are mechanically connected to a meter body 30 only at the inlet side of the inlet-side manifold 24 and at the outlet side of the outlet-side manifold 25, respectively. With this arrangement, the effects of vibration transmitted from the meter body 30 and all structures connected thereto can be reduced at the joint parts between the inlet-side and outlet-side manifolds 24 and 25 that serve as vibration fulcrums.

Abstract: Two flow tubes 1 and 2 of a Coriolis mass flow meter are formed into an arch shape, with the tubes bent in only one direction. Entry-side and exit-side manifolds 25 are smoothly bent from the inlet of the entry-side manifold and the outlet of the exit-side manifold to joints connecting the two flow tubes to the manifolds, and connected to the flow tubes 1 and 2 at the joints at a predetermined angle in the same direction. By making the flow tubes into a parallel arched tube structure having good stress distribution and shock resistance, effects on the flow meter of external oscillations, installation conditions, piping stresses and thermal stresses can be reduced.

Abstract: Each of two flow tubes assumes an arcuate shape consisting of a central arcuate segment and two linear segments located on opposite sides of the central arcuate segment. The inside diameter of the flow tubes and the linear distance between end points of each of the flow tubes are determined on the basis of a target pressure loss arising from passage of a fluid to be measured through a manifold and the flow tube at the maximum flow rate, a target time phase difference between sine wave outputs from vibration sensors at the maximum flow rate, and a target natural frequency of the flow tubes. The length of the linear segments is selected so as to reduce thermal stress induced from an abrupt change in the temperature of the fluid to be measured, and the shape of the flow tubes is determined so as to reduce the vertical height of the flow tubes, so long as the thermal stress is substantially constant even when the length of the linear segments is varied.

Abstract: A Coriolis mass flowmeter of a type in which a fluid to be measured is caused to flow in series by forming two parallel flow tubes 1 and 2, which are obtained by bending one conduit. The inlet portion of conduit between an external connecting portion 35 connected to inlet piping and the inlet of one flow tube 2 is bent in the shape of the letter L and bent in another direction in combination, and the outlet portion of conduit between an external connecting portion 36 connected to outlet piping and the outlet of the other flow tube 1 is bent in the shape of the letter L symmetrically with respect to the above inlet portion of conduit and bent in another direction in combination. The external connecting portions 35 and 36 are arranged on the same axis. The present invention simplifies the construction of connection to external piping, simplifies the assembling of the Coriolis mass flowmeter itself, and permits a high-accuracy measurement of mass flow rate by reducing the vibrations of external piping, etc.

Abstract: A double-tube type Coriolis flow meter is provided for measuring mass flow. The flow meter includes a straight flow tube (4) through which the fluid being measured flows, a hollow outer tube (5) secured at both ends thereof to act as a counterbalance, a drive unit (7), and a pair of sensors. The flow tube (4) is caused to vibrate by the drive unit (7) so that the mass flow of the fluid is measured by detecting a phase difference proportional to Coriolis force acting on the flow tube (4) by the sensors. Sheet members (coupling plates 6) secure the flow tube (4) to both ends of the outer tube (5) and integrally form the coupling plate (6) with tube-assembly supporting leaf springs (14) in the double-tube type Coriolis flow meter. By connecting the flow tube to the outer tube via the sheet members in this manner, stresses produced between the tubes are absorbed and a uniform temperature distribution is maintained in the outer tube and manufacturing costs are reduced.

Abstract: A resonantly drivable straight tube type Coriolis flowmeter which is capable of correcting instrumental errors caused by a change in density and temperature of measurable fluid. A coaxial double tube body that is composed of an inner tube wherein fluid to be measured flows and an outer tube with a balance weight attached thereto for equalizing natural frequencies of the inner and outer tubes is driven at a resonant frequency having a constant amplitude. A change of fluid density causes a change of amplitude ratio of the inner tube and the outer tube, resulting in shifting of an instrumental error. At this time, a resonant frequency detecting circuit detects a resonant frequency without detecting the amplitude ratio. An instrumental error detecting circuit stores a relation between resonant frequencies and fluid densities and a relation between fluid densities and instrument errors and conducts correction of an instrumental error according to the detected resonant frequency.

Abstract: A vortex flowmeter detector is attached to or detachable from a vortex generation body for measurement of flow rate. The vortex flowmeter detector comprises a cylindrical oscillation tube having a bottom and a vortex detection part which is fixed by a fixing flange of the oscillation tube, wherein the oscillation tube is detachably inserted into a hole which is open to the vortex generation body at one end thereof, and the oscillation tube is fixed by a flange. An alternate pressure caused by a Karman vortex is introduced from both sides of the vortex generation body into the hole so as to oscillate the oscillation tube. This oscillation is received by a spring plate by way of an element cover, and it is transmitted to piezoelectric elements which are stuck to two chamfers of an elastic base material.

Abstract: Disclosed is a Coriolis flowmeter which is capable of detecting a mass flow and a density of fluid with an increased stability by resonantly oscillating a double tube portion consisting of an inner flow tube allowing fluid to flow therein and a coaxially disposed thereon counterbalance tube provided with a weight for equalizing the lateral natural frequency of the counterbalance tube with that of the flow tube. The Coriolis flowmeter has supporting metal means for supporting the both ends of the flow tube in such a way that the both ends of the flow tube is restricted in radial directions and axially movable in respective connecting flange; the inner flow tube has extending ends enlarged in diameter and supported in the respective connecting flanges of the outer housing.

Abstract: A mass flowmeter converter detects a Coriolis force acting on a flow tube driven at a constant frequency as a time difference .DELTA.T between two displacement signals detected at symmetrically opposed positions. A mass flow proportional to the time difference .DELTA.T is determined. Sine-wave signals differing in phase and at a constant amplitude are detected paired detecting coils and provide input signals which are pulses having specified pulse width values equal to a leading time (T+.DELTA.T) and a lagging time (T+.DELTA.T). N number of pulses (T+.DELTA.T) and N number of pulses (T-.DELTA.T) are sampled simultaneously by respective integrators having the same time constant, and by using a reference power source a time difference of zero-crossing voltages and a time difference signal enlarged by 2N times is detected. Furthermore, a small time measurement error due to drifts of the charging-discharging circuit is compensated by alternating respective integrators.

Abstract: A Coriolis flowmeter of double conduit type having inner and outer conduits, is capable of effectively detecting with increased stability a Coriolis force acting on the inner fluid passage without being effected by external vibration, e.g., of piping, piping stress and a change of ambient temperature and the like. A cylindrical housing 33, connected with flanges 31 and 32 to flow piping, has a thick-walled cylindrical body 33a and end portions 33b each having a center bore 32c communicating with a cavity formed in the housing 33. The housing 33 accommodates an inner conduit 35 and an outer conduit 34 mounted coaxially with each other and secured each at both ends to the opposite end portions 33b. A vibrator 36 and sensors 37 and 38 are mounted between the inner conduit 35 and the outer conduit 34 that is equipped with an adjusting balancer 39 to obtain a resonant frequency of the same natural vibrations of the two conduits.

Abstract: A vortex flow meter capable of operating with minimum piping effect is disclosed. A stream-lined protrusion , extending toward the upstream side is disposed at the upstream surface 2 of a vortex generator joined to the inner wall 1 of a flow pipe in order to remove thereat horseshoe vortexes produced in front of the vortex generator. Therefore, the possible affection of horseshoe vortexes, that may considerably depend upon the piping conditions, can be eliminated.