JPS61290324A - Mass flowmeter - Google Patents

Abstract

PURPOSE:To achieve an effective vibration of a conduit along with a smaller size, by a method wherein the center axis YY' of a spiral conduit crosses the axis XX' of an inflow/out-flow conduit and a conduit section is supported on one side in the direction of the ZZ' axis perpendicular to these two axies while it is driven on the other side. CONSTITUTION:A conduit driving means, such as magnet or electromagnetic coil is mounted at the points A and A' as one part of the axis ZZ' of a spiral conduit 3. The spiral conduit 3 is driven in the opposite phase in such a manner that one of the spiral conduit 3 is oscillated in the direction YY' at the point A with the fastening points D1 and D2 having a support 4 present as fulcrum while the other is oscillated in the direction YY' at the A' point with the fastening points D2 and D3 as the fulcrum. At this point, the flow in the spiral conduit 3 receives a vibration and a Coriolis' force is generated at the conduit portion subjected to the vibration. The mass flow rate of a fluid flowing through the conduit can be determined from the torsion angle of the conduit proportional to the Coriolis' force.

Description

[Detailed description of the invention] ■) Industrial application fields The present invention relates to a mass flow meter that utilizes Coriolis force.

2) Conventional technology When vibration is applied to the fluid flow flowing through the flow tube.

Coriolis forces are generated in a direction perpendicular to the direction of fluid flow and the axis of vibration of the flow tube. This Coriolis force is proportional to vibration frequency and mass flow rate. Therefore, when the vibration frequency is held constant, the Coriolis force is proportional to the mass flow rate. This type of flowmeter is disclosed in Japanese Patent Application Laid-Open No. 54-52570 and Japanese Patent Application Laid-Open No. 59-1989.
Publication No. 92314 and the like are known. The former is an inlet in the support member.

The body has a fixed U-shaped conduit with an outlet, and by applying vibration in the vertical direction to the conduit surface,
This is a mass flow meter that utilizes the Coriolis force generated around the conduit symmetry axis perpendicular to the support member. In the latter case, the U-shaped conduit in the former is fixed to the inflow and outflow manifolds in a cantilevered manner with the conduit surfaces parallel to each other, and the U-shaped conduits are driven in opposite phases to each other in a tuning fork shape, thereby making the U-shaped conduits perpendicular to the manifold. The mass flow rate is determined by detecting the Coriolis force that occurs around the axis of symmetry of the conduit.

3) Problems to be Solved by the Invention In the conventional example described above, stress is concentrated at the support body that fixes the conduit, the manifold, and the fixing point of the conduit, which tends to cause fatigue rupture. Measures such as reducing the stress and lengthening the moment arm are being considered. but.

The former method is prone to deformation due to thermal strain caused by welding, making it difficult to obtain a highly accurate shape, while the latter method has problems such as an increase in the size of the shape.

4) Problems to be Solved by the Invention The present invention was made to solve the above problems by making the flow meter body as small as possible.

This allows the conduit to vibrate effectively, which is necessary to generate the Coriolis force.

5) Examples The figure shows an embodiment of a mass flowmeter according to the present invention.

The fluid flows through an inlet conduit 1 arranged along the arrow direction xx' axis.
The inflow conduit 1 is electrically connected to a spiral conduit 3 having an axis in the 7A-axis direction perpendicular to the xx' axis and wound in plural lines at an equal pitch. The outflow side of is electrically connected to the outflow conduit 2 and flows out from the outflow port 6.

Preferably, the body consists of a single conduit of equal cross-sectional area having the shape described above. In the figure, the spiral conduit is wound with 2.5 pitches.

Generally, the part communicating with the inflow conduit 1 and the part communicating with the outflow conduit 2 require a total of 0.5 pitches, so
The total number of turns is n+0°5 pitches, where n is an integer. Since a driving means to be described later is used, it is desirable that n be an even number. In addition, at the position where the axes intersect with the spiral conduit 3, I), D, and D3, which are orthogonal to each of the axis Y and the axis 87), can be swung in space by the support 4 in the TT axis direction. or on a fixed stand so that it cannot swing.

Note that the inflow conduit 1 is supported on a fixed base at the inlet 5, and the outflow conduit 2 is supported on a fixed base at the outlet 6.

The operation of the flowmeter body described above as a mass flowmeter will be explained. At other points A and A' of the 777 axis of the spiral conduit 3, conduit driving means 1 (not shown), such as a magnet and an electromagnetic coil, are attached. The electromagnetic coil is energized from an AC power source (not shown), and one of the spiral conduits is connected to a fixed point DI where the support 4 is present.

The conduit is driven to swing in 77 directions at point A using D2 as a fulcrum. The other one of the spiral conduits is attached to anchor point D2. They are driven in opposite phases so that they are swung in one direction at point A' with D3 as the fulcrum. At this time, the flow within the spiral conduit is subjected to vibration, and a Coriolis force is generated in the vibrated portion of the conduit. Looking at the action of the Cori-Ori force at points B, B' and c, c' on the conduit in the vicinity of the 7-axis V, (i) A,
When points A' are in the direction of attracting each other, point B moves toward point B', and point 0 moves away from point C'. That is, the spiral conduits are D, , D2 . With the position of D3 as a fulcrum and the zz' axis as an axis, it is twisted in a direction in which the inflow conduit 1 side is narrowed and the outflow conduit 2 side is widened, (
ii) In the half cycle in which points A and A' are driven apart, a torsional movement occurs which is completely opposite to that in case (i). and (iii) this twist angle is proportional to the Coriolis force, which in turn is proportional to the mass flow rate.

The oscillation due to this twisting occurs on the spiral conduit 3 near the xx' axis farthest from the torsion axis ZZ', B, B', C,
At this point, the Coriolis force, that is, the mass flow rate, can be measured by detecting the time difference between each of B, B', C, and C' passing through the reference plane while swinging. Make it.

6) As described above, according to the present invention, the spiral conduit 3
Since the center axis YY' of the flow rate needle passes through the point where it intersects with the axis XX' of the inflow and outflow conduits, the axis XX' passes through a position that bisects the height direction dimension of the flow rate needle.

The shape is smaller than when a U-shaped tube is used.

Regarding the drive, the bending rigidity is small because it is supported at the three points DI, Dz, and D located below the YY' axis, and is driven at the points A and A' above the YY' axis. The shape is small.

Space can be used effectively. Despite the above-described miniaturization, the length of the moment arm can be set to a desired value. Furthermore, since the surface of the spiral conduit 3 is parallel to the XX' axis, space can be utilized effectively.

[Brief explanation of the drawing]

The figure shows an embodiment of the invention. In the figure, 1 is an inflow conduit, 2 is an outflow conduit, 3 is a spiral conduit, 4 is a support, 5 is an inlet, and 6 is an outlet.

Claims (1)

[Claims] An inflow conduit and an outflow conduit for a fluid are arranged at a predetermined interval so as to substantially coincide with one axis @XX'@, and the fluid inflow conduit and outflow conduit are located at the predetermined interval, a tubular main body formed by connecting a plurality of spiral conduits whose center axis is an @YY'@ axis perpendicular to a plane containing the inflow conduit and the outflow conduit so as to communicate with the inflow conduit and the outflow conduit, respectively; @Z perpendicular to each of the @ axis and @YY'@ axis
A support part that supports the plurality of conduit sections in the @YY'@ direction at a position on one side of the spiral conduit intersecting the Z'@ axis;
The Coriolis force generated by the driving means for driving at least two conduit sections on the other side in opposite phases on the @YY'@ axis, the flow of fluid in the conduit, and the rotation of the conduit by the driving means is applied to the @XX of the conduit. A mass flowmeter characterized in that it is equipped with a detection means that detects the amount of displacement in the vicinity of the axis, and that it determines a mass flow rate that is proportional to the Coriolis force.