JPS6231851Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a wave detection device that is installed in a fluid pipe or the like to detect the wave motion of a fluid and convert it into an electrical signal or the like.

Karman vortex flowmeters are known, in which a vortex generating device equipped with a cylinder or an orifice plate is installed in a fluid pipe to generate vortices with a constant period on the downstream side, and the flow rate is measured by detecting the waves. . This type of flowmeter is equipped with a wave detection device that detects the wave motion of the fluid and converts it into an electrical signal, etc. This wave detection device is not only used for flowmeters, but also for inside pipes, etc. Used independently as a means of detecting fluid dynamic pressure.

However, in all conventional wave detection devices of this type, the detection sensitivity varies depending on the direction in which the waves travel, so when used in Karman vortex flowmeters where waves appear alternately horizontally and vertically from the vortex generator, etc. The disadvantage of this method was that it was difficult to select the mounting position of the device.

The present invention was developed in view of the above points, and consists of a cylindrical body attached to the outer wall of the fluid pipeline, and a detection rod with a circular flange that is tiltably supported with its tip facing into the fluid pipeline. By converting the tilting of the detection rod caused by waves into an electrical signal via a pressure-sensitive element and a strain-sensing element, it is possible to freely select the mounting position unaffected by the direction of the waves, and the detection sensitivity can be maintained at all times. The present invention provides a wave detection device that is easy to manufacture by ensuring compatibility and ensuring compatibility by making a pair of pressure sensitive elements the same shape.

Hereinafter, the configuration and the like will be explained in detail with reference to embodiments shown in the drawings.

Figures 1 to 3 show examples in which the wave detection device according to the present invention is implemented in a Karman vortex flow meter.
The figure is a longitudinal cross-sectional view of a Karman vortex flowmeter implementing this method, FIG. 2 is a partially cutaway perspective view of the same, and FIG. 3 is a longitudinal cross-sectional view of a wave detection device. In the figure, the upstream piping 1 and the downstream piping 2 with respect to the fluid flow direction indicated by arrow A have connecting flanges 1
a, 2a are integrally formed, and these connecting flanges 1a, 2a are joined with bolts with gaskets 3 and 4 and an orifice plate 5 for vortex generation interposed therebetween. The orifice plate 5 is formed of a thin plate into a disc shape, and a knob 5 for attaching and detaching is provided at one location on the outer periphery of the orifice plate 5.
a is integrally formed. In addition, orifice plate 5
A semicircular fluid passage 5c is formed by dividing a circular hole having a diameter slightly smaller than the inner diameter of the pipes 1 and 2 symmetrically with a partition plate 5b passing through the center. By passing through the fluid passage 5c of the orifice plate 5, the fluid generates a so-called Karman vortex in which vortices with different rotational directions alternately appear in the pipe 2 after passing, and the overall flow is indicated by arrow B. meandering like that.

On the downstream side of the vortex generator configured as described above, a wave detection device 6 whose sectional view is shown in FIG. It is arranged so as to be screwed into the screw hole No. 8. Inside the cylindrical body 7, there is a pressure detection chamber 9 and a pair of mutually continuous bellows chambers 10, 11.
The bellows chamber 10 and the bellows chamber 11 have different diameters and form a stepped inner chamber. Further, the lower bellows chamber 11 and the inside of the pipe 2 are communicated through a detection rod chamber 12.

Furthermore, inside the pressure detection chamber 9, a semiconductor type strain detection element 13 is provided fixed to the inner wall.
In the pressure detection chamber 9, pressure receiving chambers 14 and 15 are separated by the strain detection element 13. In the lower bellows chamber 11 and detection rod chamber 12,
A detection rod 16 is inserted with its circular brim-shaped lever plate 17 engaged with the stepped portions of both chambers 10 and 11,
The detection rod 16 has a detection portion that is continuous with the lever plate 17 protruding from the detection rod chamber 12 and has its tip facing near the center of the fluid conduit in the piping 2. By forming it with a large diameter, it is configured to be able to tilt around the engaging peripheral edge of the lever plate 17.

Furthermore, inside the upper and lower bellows chambers 10 and 11,
A pair of pressure sensitive bellows 18 and 19 are connected to the detection rod 1
The pressure-sensitive bellows 18 are arranged concentrically with the lever plate 17 of 6 in between, and the pressure-sensitive bellows 18 has both end openings securely fixed to the ceiling wall of the bellows chamber 10 and the upper surface of the lever plate 17, respectively. has been done. In addition, the other pressure sensitive bellows 19 has both end openings connected to the lever plate 1.
7 and the bottom stepped portion of the bellows chamber 11 in a secure manner. And pressure sensitive bellows 1
The inside of the pressure sensitive bellows 18 and the pressure receiving chamber 14 of the pressure detection chamber 9 are communicated with each other by a passage 20 passing through the shaft core.
5 through a bypass-like passage 21. And the pressure sensitive bellows 1 communicating in this way
8, the passage 20, and the pressure receiving chamber 14 are filled with a sealed liquid 22, and the pressure sensitive bellows 18 and 19 are interlocked by the tilting of the detection rod 16, and the passage 21 and the pressure receiving chamber 15 are filled with a liquid 22. , another filling liquid 23 is sealed. Further, the strain detection element 13 is connected to a receiving instrument via lead wires 24, 25 and terminals 26, 27.

In addition, although the cylindrical main body 7 is shown as being integrally formed as a whole in the figure, the strain detecting element 13, the pressure sensitive bellows 18, 19, and the detecting rod 1
Needless to say, in order to make it possible to mount 6, it is actually divided into parts as appropriate in the axial direction.

The operation of the Karman vortex flowmeter configured as described above will be explained. When the fluid flows as shown by arrow A and passes through the fluid passage 5c of the orifice plate 5, this fluid flows around to the downstream side of the partition plate 5b and generates a Karman vortex. The number of Karman vortices generated is proportional to the flow velocity per unit time, and as vortices with different directions appear alternately, the entire flow meanderes as shown by arrow B, creating waves with a period proportional to the flow velocity. appears. When pressure from this wave is applied to the detection rod 16 of the wave detector 6, the detection rod 16 tilts around the fulcrum at the lower peripheral edge of the lever plate 17, so that the upper pressure-sensitive bellows 18
, the pressure fluctuation is transmitted to the strain detection element 13 communicating with it via the passage 20 by the sealed liquid 22 inside the strain detection element 13 . Also, at the same time, both pressure-sensitive bellows 1
The sealed liquid 23 on the outside of the strain sensing elements 8 and 19 transmits pressure fluctuations to the opposite side of the strain sensing element 13 through the passage 21, and these pressure fluctuations on both sides of the strain sensing element 13 are converted into electrical signals and sent to the terminals 26 and 27. and transmitted to the receiving instrument.

FIG. 4 is a cross-sectional view of the fluid pipe for explaining the flow of fluid, and as is clear from the figure, the fluid flowing in parallel as shown by arrow A in the pipe 1 flows through the orifice plate 5. When it passes through the fluid passage 5c, it becomes a meandering flow indicated by the symbol B, and when the flow direction of this meandering flow is taken on the center line E of the piping 2,
Its direction changes periodically. That is, the flow direction of the fluid at the moment it leaves the orifice plate 5 is almost parallel to the center line E, but gradually changes the flow direction to a direction perpendicular to this and approaches the vertical direction most at point F. , after which the flow direction is changed to the parallel direction, and the cycle is repeated. On the other hand,
In this device, the wave detection member is formed in the shape of a round bar, and a lever plate 17 with a circular flange is provided on the head thereof.
Since this lever plate 17 is supported by the steps of the bellows chambers 10 and 11, no matter which direction the wave motion acts on the detection rod 16 within 360 degrees, the detection rod 16 will be able to move the lever plate 17 in the same way. It tilts using the lower peripheral edge as a fulcrum. Therefore, the wave detection device 6 operates in the same way no matter where it is installed on the downstream side of the orifice plate 5, so it can be installed at any position and can always provide high wave detection. Sensitivity can be ensured.

Furthermore, in this device, the pressure-sensitive bellows 18 and 19 are formed to have the same shape and the same capacity, so they are compatible, easy to manufacture, and can reduce inventory.

In this example, an example in which the present invention is applied to a Karman vortex flowmeter is shown, but the present invention is not limited to this, and can be widely used as a means for detecting the dynamic pressure of a fluid in a pipe, etc. It is something that can be done.

As is clear from the above explanation, in the wave detection device according to the present invention, a detection rod with a circular flange is attached to the cylindrical body attached to the outer wall of the fluid pipe with its tip facing into the fluid pipe. By supporting the detection rod so that it can be tilted freely and converting the tilting movement of the detection rod caused by waves into an electrical signal via a pressure-sensitive element and a strain detection element, the detection rod can be easily supported regardless of the direction in which pressure is applied by waves. Since they tilt in the same way, you can freely select the mounting position of the detection device, ensuring high detection sensitivity at all times, and making the pair of pressure sensitive elements the same shape and capacity makes it easy to manufacture. This makes it possible to reduce inspection and inventory quantities.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of the wave detection device according to the present invention, Figure 1 is a vertical cross-sectional view of a Karman vortex flowmeter implementing this, and Figure 2 is a partially cutaway view of the same. A perspective view, FIG. 3 is a vertical sectional view of the wave detection device, and FIG. 4 is a cross sectional view of a fluid conduit for explaining the flow of fluid. 1, 2...Piping, 6...Wave detection device, 7...
Cylindrical body, 10, 11... Bellows chamber, 12...
Detection rod chamber, 13... Strain detection element, 16... Detection rod, 17... Lever plate, 18, 19... Pressure sensitive bellows, 20, 21... Passage, 22, 23... Filled liquid.

Claims (1)

[Scope of utility model registration request] A cylindrical body that is attached to the outer wall of the fluid conduit and includes a stepped inner chamber and a detection rod chamber that opens continuously to the fluid conduit, and a circular collar that engages with the step of the inner chamber. and a detection portion extending continuously from the detection rod chamber toward the inside of the fluid conduit; a pair of pressure-sensitive elements, each having one opening fixed to both sides of the circular flange and the other opening fixed to an inner wall at both ends of the inner chamber; a semiconductor-type strain detection element that is arranged to partition off a sealed liquid passage that communicates the inside and outside of the pressure sensitive element on the opposite side of the detection part with respect to the flange part, and converts pressure changes of the fluid into an electrical signal; A wave detection device characterized in that a pair of pressure sensitive elements have the same shape.