JP3017787B2 - Fluidic flow meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention detects an alternating pressure wave generated by a vibration phenomenon of a fluid such as gas ejected from an ejection nozzle into a flow path and detects a flow rate of the alternating pressure wave. To a fluidic flow meter that detects

(Prior Art) Fluidic flow meters installed in ordinary households and the like for measuring the flow rate of gas are disclosed in, for example, JP-A-63-313018,
It is known from JP-A-1-250725. In this fluidic flow meter, an ejection nozzle is provided in a partition wall that separates an upstream channel and a downstream channel of a channel, and a fluid is ejected from the ejection nozzle to a fluidic element provided in a downstream channel. Then, the jet fluid flows, for example, along the right side wall due to the Coanda effect. A part of the fluid flowing to the right side wall becomes return fluid, and the fluid energy of this return fluid is applied to the ejected fluid, and the ejected fluid flows along the left side wall, and then flows to the left side wall. A part of the returned fluid becomes a return fluid, and the fluid energy of the return fluid is applied to the jet fluid, and the jet fluid flows again along the right side wall. That is, an alternating pressure wave is generated by the vibration phenomenon of the fluid ejected from the ejection nozzle into the flow path. The alternating pressure wave is detected by the piezoelectric film sensor, and the flow rate is calculated from the frequency to detect the flow rate of the fluid.

(Problems to be Solved by the Invention) By the way, in the fluidic flow meter, the fluid flowing in from the inlet body of the case body is guided to the ejection nozzle via the upstream flow path, and the fluid ejected from the ejection nozzle is Although the fluid flows into the fluidic element, when the fluid flowing from the inflow body passes through the upstream-side flow path, the fluid flows through the bent flow path, and turbulent flow is generated due to the unevenness of the inner wall of the flow path. When the turbulent flow occurs in the upstream flow path, the flow velocity of the fluid passing through the ejection nozzle is disturbed, and the alternating pressure wave in the fluidic element is also adversely affected, so that the flow rate cannot be accurately measured.

The present invention has been made in view of the above circumstances, and its object is to rectify the turbulent flow of the fluid in the upstream flow path of the flow path main body, and to perform accurate measurement, It is an object of the present invention to provide a fluidic flow meter that can easily attach a current plate and can improve assembling workability.

[Constitution of the Invention] (Means and Actions for Solving the Problems) In order to achieve the above object, the present invention provides an upstream channel and a downstream channel by providing a partition in a channel main body constituting a channel. And a discharge nozzle for discharging the fluid of the upstream flow path to the downstream flow path, a fluidic element is provided for the downstream flow path, and a flow path main body constituting the upstream flow path. At least two grooves are provided on the inner surface of the upstream side channel in the width direction of the upstream channel, and a flow straightening plate composed of a support body integrally formed by inserting the groove at both ends of the mesh body is formed. A body is inserted from one end side of the concave groove to support a flow straightening plate in the flow channel body.

Fluid flowing in the upstream flow path is rectified when passing through the flow straightening plate, and the rectified fluid is jetted from the jet nozzle to the downstream flow path, so that the alternating pressure wave in the fluidic element is also adversely affected. And the flow rate can be measured accurately.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 8 and FIG. 9 show the entire fluidic flow meter, and 11 is a case. The case 11 includes a rectangular box-shaped case main body 12 and a lid 13 that closes an opening of the case main body 12. A gas inlet 14 and a gas outlet 15 are provided side by side at the lower part of the case body 12, and a flow rate display window (not shown) is provided at the upper part. At the lower portion inside the case 11, a fluidic element 17 and a shutoff valve 18, which will be described later, are provided.

The fluidic element 17 will be described. 23 is a channel body formed by die-casting or the like, and the opening of the channel body 23 is closed by a lid 25 via a packing 24 to form a channel 26. Is configured.
The flow path 26 is defined by a partition wall 27, the upstream flow path 28 communicates with the gas inlet 14, and the downstream flow path 29 communicates with the gas outlet 15. A valve seat 30 is provided in the middle of the upstream flow passage 28, and the valve seat 30 of the shutoff valve 18 is provided in the valve seat 30.
Are facing each other. That is, the flow path 26 can be shut off by the shut-off valve 18 when the seismic sensor or the like detects an abnormality.

A jet nozzle 32 is provided on the partition wall 27 of the flow path main body 23. The ejection nozzle 32 has a slit shape that opens over the entire depth direction of the flow path main body 23, and has projections 32a and 32b that protrude into the upstream flow path 28 on both side edges in the longitudinal direction thereof. The length has been extended. This jet nozzle 32
A first target 33 for stabilizing the switching of the flow direction of the fluid is provided in the downstream flow path 29 opposite to the first flow path. Side walls 34a and 34b are provided symmetrically on both sides of the first target 33. Further, a second target is located at a central portion located downstream of the first target 33.
A return wall 36 is further provided on the downstream side and extends in the width direction of the downstream flow path 29. Then, return channels 37a, 37b are formed outside the side walls 34a, 34b, and discharge channels 38a, 38b are provided outside both ends of the return wall 36.

Therefore, when the fluid is ejected from the ejection nozzle 32 toward the downstream flow path 29, the ejected fluid flows along, for example, the inside of the right side wall 34a due to the Coanda effect.
Most of the fluid flowing to the right side wall 34a is discharged to the discharge passage 38a.
, But a part thereof becomes the return fluid and goes to the return passage 37a. The fluid energy of the return fluid is applied to the ejected fluid, and the ejected fluid flows along the inside of the left side wall 34b, and a part of the fluid flowing to the left side wall 34b becomes the return fluid this time, The fluid energy of the fluid is applied to the ejected fluid, and the ejected fluid again flows along the inside of the right side wall 34a. That is, the configuration is such that the alternating pressure wave is generated by the vibration phenomenon of the fluid ejected from the ejection nozzle 32 into the downstream flow path 29.

Further, the flow path main body 23 corresponding to the ejection nozzle 32
A flow sensor 40 and a piezoelectric film sensor 41 are provided at the bottom of the sensor. The flow sensor 40 includes a sensor main body 42 and a sensor chip 43 including a detection unit including a heating unit and a temperature sensing unit.
The sensor body 42 is fixed to the bottom of the flow path body 23, and the sensor chip 43 faces the ejection nozzle 32.
That is, the flow sensor 40 is installed at a position where the flow path is narrowed and the flow velocity becomes the fastest in order to measure the minute flow rate region. Further, the piezoelectric film sensor 41 is for measuring in a large flow rate region, and includes a sensor main body 44 and a pressure wave introducing section 45, and fixes the sensor main body 44 to the bottom of the flow path main body 23, The wave introduction part 45 communicates with a pair of pressure wave introduction ports 46, 46 which are opened near the outlet of the jet nozzle 32 at the position where the alternating pressure wave generated by the vibration phenomenon is optimally extracted.

On the other hand, a first rectifying plate 47 to be described later is
And a second rectifying plate 48, which are provided detachably with respect to the flow path main body 23.

The first current plate 47 and the second current plate 48 are shown in FIGS.
It is configured as shown in the figure and is attached to the flow path main body 23. That is, on the inner surface located near the open end of the flow path main body 23 and the partition wall 27 constituting the upstream flow path 28, concave grooves 50, 50 facing each other up and down are provided, and the bottom of the flow path main body 23 Is provided with a slit groove 50a.
On the other hand, the first current plate 47 is composed of a rectangular net 51, and supports 52, 52 formed integrally by inserting upper and lower corners at the base end of the net 51. . The mesh 51 is substantially equal to the cross-sectional area of the upstream channel 28, and the support 52 is formed in a size that can be densely inserted into the concave groove 50. Then, the mesh member 51 is vertically inserted into the upstream channel 28 from the tip end thereof, and further, the tip portion of the mesh member 51 is inserted into the slit groove 50a, and the support members 52, 52 are formed into the concave grooves 50,5.
0, the first rectifying plate 47 is
8 is supported in a state of partitioning.

The partition wall 27 constituting the upstream flow path 28 is provided with a groove 53 on each side of the ejection nozzle 32. These concave grooves 53, 53 are provided over the entire length in the width direction of the upstream flow path 28, and the first groove formed wide at the base end side thereof, that is, at a portion located near the opening end of the flow path main body 23. The engaging portion 53a is provided with a second engaging portion 53b formed of a concave portion which is depressed in the extension direction of the concave groove 53 on the distal end side, that is, on the bottom portion of the flow path main body 23. On the other hand, the second current plate 4
Reference numeral 8 denotes a net-like body 54 bent into a mountain shape, and supports 55, 55 integrally formed by inserting the edges of both legs of the net-like body 54. The mesh member 54 is formed in a size sufficient to cover the protruding portions 32a and 32b protruding into the upstream channel 28. Also, the supports 55, 55
At the base end, there is provided an engagement projection 55a that is densely inserted into the first engagement portion 53a of the concave groove 53, and at the distal end, a second engagement portion 53b is provided.
It has a tip portion 55b that is densely inserted into the end portion. When attaching the second current plate 48, the distal end 55b of the support 55, 55 is inserted from the end of the concave groove 53, 53 so that the distal end 55b is inserted into the second engaging portion 53b. And the engaging projection 55a is in the first position.
The second straightening plate 48 can be prevented from being lifted up by engaging with the engaging portion 53a, and is supported so as to partition the upstream side of the ejection nozzle 32.

Further, the support 5 of the first and second rectifying plates 47, 48 is provided.
2, 55 are pressed toward the bottom of the flow path main body 23 by the lid 25 that closes the opening of the flow path main body 23 through the packing 24, so that the flow path main body is not fixed by a special fixing member.
Fixed to 23.

Next, the operation of the fluidic flow meter configured as described above will be described. The fluid flowing from the gas inlet 14 flows through the upstream channel 28 of the channel 26. At this time, even if turbulence occurs in the fluid, the first current plate 47 and the second current plate
The nozzle 3 is rectified when passing through the 48 meshes 51 and 54
Head to 2. Since the flow path of the ejection nozzle 32 is narrowed, the flow velocity of the fluid increases, and the flow path 29
The fluid is ejected. When the fluid passes through the ejection nozzle 32, its flow velocity is detected by the flow sensor 40. When the fluid is ejected from the ejection nozzle 32 toward the downstream flow path 29, the ejected fluid flows, for example, along the inside of the right side wall 34a due to the Coanda effect. Most of the fluid flowing to the right side wall 34a goes to the discharge passage 38a, but part of it becomes return fluid and goes to the return passage 37a. The fluid energy of the return fluid is applied to the ejected fluid, and the ejected fluid flows along the inside of the left side wall 34b, and a part of the fluid flowing to the left side wall 34b becomes the return fluid this time, The fluid energy of the fluid is applied to the ejected fluid, and the ejected fluid again flows along the inside of the right side wall 34a. That is, an alternating pressure wave is generated due to the vibration phenomenon of the fluid ejected from the ejection nozzle 32 into the downstream flow path 29. This alternating pressure wave, that is, a pressure change caused by a change in the flow direction of the jet from the jet nozzle 32, is detected by the piezoelectric film sensor 41 via the pressure wave inlets 46,46.

The waveform signals from the flow sensor 40 and the piezoelectric film sensor 41 calculate the fluid flow rate from the frequency and display the calculated fluid flow rate on the flow rate display window.

In mounting the flow sensor 40 and the piezoelectric film sensor 41 to the flow path main body 23, the flow sensor 40 and the piezoelectric film sensor 41 are mounted on the same side surface of the flow path main body 23 in the same direction. Can be improved,
Further, workability is improved during maintenance and inspection and repair.

In the above embodiment, the first and second rectifying plates are provided in the upstream flow path, but the number of rectifying plates may be one.

[Effects of the Invention] As described above, according to the present invention, the fluid flowing through the upstream flow path is rectified when passing through the flow straightening plate, and the rectified fluid is jetted from the ejection nozzle to flow downstream. Since the flow goes to the path, the flow rate can be accurately measured without adversely affecting the alternating pressure wave in the fluidic element. Further, at least two grooves are provided in the width direction of the upstream side flow path, and a straightening plate made of a support body integrally formed by inserting the grooves at both ends of the mesh body is formed. The flow straightening plate is inserted from one end of the groove to support the flow straightening plate for straightening the fluid flowing from the upstream flow passage toward the downstream flow passage in the flow passage main body, so that the flow straightening plate can be easily attached and the assembling workability can be improved. This has the effect.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention. FIG. 1 is a vertical sectional front view of a flow path main body of a fluidic flow meter showing a mounting structure of a current plate, and FIG. 2 is a sectional view taken along line II-II of FIG. FIG. 3 is a perspective view showing a mounting structure of the first current plate, FIG. 3 is a vertical side view taken along a line IV-IV of FIG. 4, and FIG. 5 shows a mounting structure of the second current plate. FIG. 6 is a perspective view, and FIG.
7 is a front view, FIG. 8 is a partially cutaway front view of the fluidic flow meter, and FIG. 9 is a partially cutaway side view of the same. 23 ... channel body, 26 ... channel, 27 ... partition wall, 28 ... upstream channel, 29 ... downstream channel, 32 ... jet nozzle, 47 ...
1st current plate, 48 ... second current plate, 50, 53 ... groove, 5
1,54 ... net, 52,55 ... support.

Claims (1)

(57) [Claims] 1. A flow path main body constituting a flow path, a partition is provided to divide an upstream flow path and a downstream flow path, and the fluid of the upstream flow path is jetted to the downstream flow path at the partition. In a fluidic flow meter provided with a nozzle and a fluidic element in the downstream flow path, at least two concave portions are formed on the inner surface of the flow path main body constituting the upstream flow path in the width direction of the upstream flow path. While the groove is provided, a flow straightening plate composed of a support body integrally formed by inserting the support body at both ends of the mesh body is formed, and the support body is inserted from one end side of the concave groove and upstream of the flow path main body. A fluidic flow meter characterized by supporting a flow straightening plate for rectifying a fluid flowing from a side flow path to a downstream flow path.