JPH0455252B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application The present invention relates to a mass flowmeter that utilizes the Coriolis force.

2. Prior Art When vibration is applied to a fluid flow flowing through a 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. As this type of flow meter,
Publication No. 52570, Japanese Unexamined Patent Publication No. 59-92314, etc. are known. The former has a main body shape in which a U-shaped conduit with an inlet and an outlet is fixed to a support member, and by applying vibration in a direction perpendicular to the conduit surface, it is possible to generate vibrations around the axis of symmetry of the conduit perpendicular to the support member. This is a mass flow meter that utilizes the Coriolis force generated in the flow. 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 that fixes the conduit, the manifold, and the fixing point of the conduit, so fatigue rupture is likely to occur, and to prevent this, locally thick walls are used. Measures such as reducing the stress and lengthening the moment arm are 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 has been made to solve the above-mentioned problems, and is to reduce the size of the flowmeter body as much as possible, and to reduce the number of conduits necessary to generate the Coriolis force. This allows for effective vibration.

5 Embodiment The figure shows an embodiment of the mass flowmeter according to the present invention. The fluid flows in from the inlet 5 of the inflow conduit 1 arranged along the 'axis' in the direction of the arrow, but the inflow conduit 1 has an axis in the 'axis direction perpendicular to the 'axis' and is wound in multiple strips at equal pitches. It is electrically connected to the spiral conduit 3 , and the outflow side of the spiral channel 3 is electrically connected to the outflow pipe 2 and flows out from the outlet 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 2.5 pitches.
In general, a portion communicating with an inflow conduit 1 and an outflow conduit 2
The total number of windings is n+, where n is an integer.
It becomes 0.5 pitch. 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 axis ' which is perpendicular to each of the axis ' and ' axis ' intersects with the spiral conduit 3,
D ₁ , D ₂ , and D ₃ are supported swingably in space by a support 4 or non-swingably supported on a fixed base. 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' on the axis of the spiral conduit 3, there is a conduit driving means (not shown), for example,
Magnets and electromagnetic coils are attached. The electromagnetic coil is energized from an AC power source (not shown), and one of the spiral conduits is connected to fixed points D ₁ and D ₂ where the support 4 is present.
The conduit is driven to swing in the 'direction' at point A using the point A as a fulcrum. The other spiral conduit is at point A′ with fixed points D ₂ and D ₃ as fulcrums.
They are driven in opposite phases to swing in the YY′ direction. At this time, the flow within the spiral conduit is subjected to vibration, and Coriolis force is generated in the vibrated portion of the conduit. Looking at the effects of the Coriolis force at points B, B' and C, C' on the conduit near the 'axis, () if points A and A' are in the direction of attraction to each other, point B is in the direction of point B'. Direction close to,
Point C moves away from point C'. That is, the spiral conduit is twisted in a direction in which the inflow conduit 1 side is narrowed and the outflow conduit 2 side is widened, with the positions of D ₁ , D ₂ , and D ₃ as fulcrums and the ZZ' axis as the axis.
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 (). () This twist angle is proportional to the Coriolis force and proportional to the mass flow rate. The oscillation due to this torsion appears most strongly on the spiral conduit 3 near the XX' axis B, B', C, and C', which is farthest from the torsion axis ZZ'. The time difference between each of C and C' as they pass while swinging is detected to measure the Coriolis force, that is, the mass flow rate.

6 Effects As described above, according to the present invention, the central axis YY' of the spiral conduit 3 is the axis of the inflow and outflow conduits.
Since it passes through the point where it intersects with XX', the axis XX' passes through the position that bisects the height dimension of the flowmeter.
The shape is smaller than when a U-shaped tube is used. Regarding the drive, since it is supported at _three points D ₁ , D ₂ , and D located below the YY′ axis, and driven at points A and A′ above the YY′ axis,
Although the bending rigidity is low, the shape is small and space can be used effectively. Despite the above-described miniaturization, the length of the moment arm can be set to a desired value. Furthermore, the surface of spiral conduit 3
Since it is parallel to the XX' axis, space can be used 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)

[Scope of Claims] 1. A fluid inflow conduit and a fluid outflow conduit are arranged at a predetermined interval so as to substantially coincide with one axis', and the fluid inflow conduit and outflow conduit are located at the predetermined interval, and are perpendicular to a plane containing the axis'. It has a tubular main body formed by connecting a plurality of spiral conduits whose central axis is the '' axis in the direction so as to communicate with the inflow conduit and the outflow conduit, respectively, and which is orthogonal to each of the '' and '' axes. At the position on one side of the spiral conduit that intersects the ′ axis
A support part that supports a plurality of conduit sections in the YY' direction, a driving means that drives at least two conduit sections on the other side in opposite phases to each other on the ' axis, and a control section that controls the flow of fluid in the conduit and the movement of the conduit by the driving means. What is claimed is: 1. A mass flowmeter comprising: detection means for detecting Coriolis force caused by rotation as a displacement amount in the vicinity of the ′ axis of a conduit, and determining a mass flow rate proportional to the Coriolis force.