JP2003247875A - Ultrasonic flow measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve measuring accuracy and carry out minimization by eliminating drift generated by the bending of a passage very near to an opening and closing valve on the passage of an ultrasonic flow measuring means and reduction of a sectional thereof. <P>SOLUTION: The ultrasonic flow measuring device is provided with a fluid control means 25 provided adjacent to the downstream of the opening and closing valve 23 at the upper stream side of a measuring passage 1, the bending 31 toward the measurement passage 1, and a rectification means 32 at the inlet of the measuring passage 1, and then suppress the drift generated at the down stream of the opening and closing valve 23 on the passage with the fluid control means 25. The fluid control means 25 formed with a plate member and a baffle board with porosity can suppress the drift suiting the strength of the drift with the inclination of the plate member, the opening degree of a hole, and distribution density. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flow rate measuring device for measuring the flow rate and flow velocity of gas or liquid by ultrasonic waves.

[0002]

2. Description of the Related Art Conventional ultrasonic flow rate measuring devices of this type are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 9-18591 and 11-.
No. 3519926 is known, and FIG.
The example of 18591 is shown.

In FIG. 9, a pair of ultrasonic transmitters / receivers 2 and 3 are provided on the peripheral surfaces facing each other with the center line of the measurement flow path 1 through which the fluid to be measured flowing and having a predetermined angle with respect to the center line. A rectifying body 6 composed of a plurality of thin tubes 5 arranged in parallel is provided in the fluid inlet 4 of the measurement flow path 1 in the same direction as the measurement flow path 1. Then, ultrasonic waves are transmitted and received between the ultrasonic transceivers 2 and 3 in the forward and reverse directions with respect to the flow of the fluid, the flow velocity is measured from the propagation time difference in both directions, and the flow rate is calculated from the cross-sectional area of the pipe. There is. At this time, the flow entering the measurement flow path 1 is regulated by the thin tube 5 forming the rectifying body 6 so that the flow direction is the same direction as the measurement flow path 1 to reduce the inclination of the flow line in the measurement section, or to reduce the vortex. Is suppressed to reduce the fluctuation of the reception level of the ultrasonic wave due to the reflection and bending of the ultrasonic wave at the boundary surface of the flow turbulence, thereby preventing the deterioration of the measurement accuracy.

As another example, JP-A-11-3519
Examples in Japanese Patent No. 26 are shown in FIGS. Figure 10
9, the measurement flow path 1, the ultrasonic transmitters / receivers 2, 3, and the fluid inlet 4 are the same as those in the example shown in FIG.
Instead of the rectifying body 6, a flow direction restricting means 7 and a flow fluctuation suppressing means 8 are provided. As shown in FIG. 11, the flow direction regulating means 7 is provided with several vertical partition plates 9 and horizontal partition plates 10 that divide the flow path into fine parts, and partition plates 9 and 1 are provided.
The flow direction is regulated by the inclination provided at 0, and the flow direction of the measurement flow path is aligned in a desired direction like the thin tube 5 of the rectifying body 6 in FIG. The fluctuation suppressing means 8 has a large number of finely-shaped connecting passages arranged in the cross section of the measurement passage, and is made of a mesh net, a foam such as plastic or foam metal, a pressed plate, an etched plate, or a non-woven fabric. Alternatively, a plurality of them are combined, and the fine communication paths prevent flow fluctuations in the measurement flow path 1 and rectify the flow. In addition, JP-A-11-
Japanese Patent No. 351926 discloses an example in which the fluctuation suppressing means 8 and the flow direction restricting means 7 can be installed individually or adjacently.

As described above, the rectifying body 6 having the thin tube 5,
The flow direction restricting means 7 for restricting the flow direction and the fluctuation suppressing means 8 having fine holes are installed at the measurement flow path inlet 4 to improve the non-uniform flow velocity distribution of the fluid flowing through the flow path, and to improve the flow speed. It was provided for the purpose of rectifying the fluid flowing through the measurement flow path 1 and improving the measurement accuracy of the flow rate by uniforming the instantaneous fluctuation of

[0006]

However, in the above-mentioned conventional structure, the flow path is bent or narrowed at a short interval necessary for downsizing the flow rate measuring device, the flow path of the on-off valve is bent, and the local flow is locally applied. When there is a large change in the cross-sectional area, uneven flow occurs at the bent portion, and the reduction of the cross-sectional area of the flow path increases the intensity of the uneven flow and the turbulent flow. The thin tube type rectifier 6 of FIG. 9 requires a relatively long thin tube 5 having a diameter-length ratio of about 1 to 10 for adjusting the flow direction, so that the flow rate measurement path becomes large and the pressure loss becomes large. There is a problem that the measurable upper limit flow rate is limited. Further, if the flow direction regulating means 7 is installed alone, the direction of the drift can be changed, but there is a problem that the effect of weakening the strength of the drift is small. Also in the fluctuation suppressing means 8, the flow rate of the fluid passing through one fine hole is increased to regulate the flow rate, and the fluid is uniformly flowed through the whole fine hole provided on the entire surface of the fluctuation suppressing means 8. Since the flow velocity distribution in the road is improved, if there is a severe drift,
There is a problem that this cannot be alleviated or suppressed, or that pressure loss becomes excessive in order to obtain a desired drift prevention effect. Further, the flow direction regulating means 7 and the fluctuation suppressing means 8
Even in the case where and are installed close to the inlet 4 of the measurement flow path 1, when the flow rate increases and a severe drift occurs, the rectifying effect cannot be exerted, and a drift or overflow occurs in the measurement flow path. However, there is a problem that the accuracy of the flow rate measurement is changed due to the generation of the drift or the vortex, the change of the generation position, and the disappearance.

The present invention is intended to solve the above-mentioned problems, in which strong uneven flow prevention is performed before reaching the inlet of the measurement flow path, and further rectification or flow direction regulation and rectification is performed at the measurement flow path inlet. By improving the flow rate distribution of the fluid flowing through the measurement flow path, the flow path is shortened, downsized, and the measurement accuracy is improved.
An object of the present invention is to provide a flow rate measuring device in which the entire device is downsized.

The rectifying body 5, the flow direction regulating means 7, and the flow fluctuation suppressing means 8 provided at the inlet 4 of the measurement flow path 1 described in the conventional example are collectively referred to as rectifying means in the present invention. .

[0009]

In order to solve the above-mentioned conventional problems, a flow rate measuring device of the present invention is provided at an opening / closing valve, an introducing passage formed by a downstream passage of an opening / closing valve, a bending portion, and a measurement passage inlet. In the flow path configuration including the rectifying means, the measurement flow path, and the discharge bending portion, the fluid control means is provided in the flow path on the downstream side of the on-off valve.

As a result, when the flow of the fluid passes through the on-off valve, it is bent at the on-off valve portion and collided against the opposite wall surface of the flow passage on the downstream side of the on-off valve, and the uneven flow is generated on the entire flow passage by the fluid control means. The diffusion is alleviated, the mixture is agitated at the curved portion, and the flow velocity distribution is improved by the rectifying means provided at the inlet of the meter side flow passage, and the pulsation of the flow rate generated at a short interval is reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is characterized in that an inlet passage having an on-off valve and a fluid control means disposed on the downstream side of the on-off valve, and an inlet passage bent in the axial direction of the inlet passage. A measurement flow path provided, at least a pair of ultrasonic transceivers provided on opposite wall surfaces sandwiching the flow path of the measurement flow channel, and measurement control means for measuring the propagation time of ultrasonic waves between the pair of transceivers. And an ultrasonic flow rate measuring device comprising a calculation means for calculating a flow rate based on a signal from the measurement control means, whereby the fluid is bent at the valve seat opening of the on-off valve mounted on the wall surface of the flow path. The flow control means suppresses and alleviates uneven flow caused by flowing into the downstream side flow path, colliding with the facing wall surface of the downstream side flow path and then flowing to the downstream side along the flow path wall surface,
After mixing at the bend, the direction is changed, and the rectifying means installed at the inlet of the meter side flow channel further receives the rectifying action, improving the flow velocity distribution in the measurement flow channel and pulsating the flow rate generated at short intervals. Can be reduced.

The invention as defined in claim 2 is particularly defined by claim 1.
By covering the introduction passage with the fluid control means described in (1) and forming a plate-like member having porosity in the direction of the passage, the drift can be diffused and eliminated in the entire passage.

The invention as defined in claim 3 is particularly defined by claim 2.
Since the fluid control means described in (1) is a plate-shaped member having inclined porosity so that the portion with the strongest drift in the flow path is the upstream side and the portion with the weakest drift is the downstream side, the drift is inclined. The porous plate-shaped member easily spreads along the surface of the porous plate-shaped member, and the fluid evenly passes through the holes provided on the entire surface of the plate-shaped member to reduce the pressure loss in the fluid control means and enhance the effect of suppressing the non-uniform flow. You can

The invention as defined in claim 4 is particularly characterized by claim 3.
Since the fluid control means described above is a porous plate-like member having an opening area in which the passage pressure loss becomes lower toward the downstream side, the biased flow having a strong momentum exerts a large momentum at the hole having a large passage pressure loss on the upstream side. The fluid that has been shaved and diffused along the surface of the slanted porous plate member and whose momentum has been attenuated can pass through the small passage pressure loss hole on the downstream side with a slight reduction in momentum. The flow passing through the holes of the member can be equalized, and the effect of suppressing the nonuniform flow in the fluid control means can be enhanced and the pressure loss can be reduced.

According to a fifth aspect of the present invention, in particular, the fluid control means according to the second, third, and fourth aspects is a plate-like member having no fluid passage hole in a portion of the flow path where the most biased flow strikes. By doing so, the strongest drift is prevented from passing through the fluid passage hole on the upstream side of the plate member and leaking to the downstream side with strong force, and the fluid is passed through the hole provided on the downstream side of the plate member. As a result, the effect of suppressing uneven flow in the fluid control unit can be enhanced.

According to the sixth aspect of the present invention, in particular, the fluid control means according to the fourth and fifth aspects is a porous plate-like member having a cutout portion in the downstream side portion where the most uneven flow is weak.
When the flow rate is small, the pressure loss caused by the fluid control means can be reduced by flowing through the holes of the plate-shaped member and the notch.

The invention as defined in claim 7 is particularly defined by claim 1.
The fluid control means described is a plate-shaped member in which the portion with the strongest drift in the flow channel is the upstream side, the portion with the weakest drift is the downstream side, and there is a notch in the downstream portion, and By constructing with an eaves-shaped baffle plate provided on the downstream side of the notch, the fluid that has lost its momentum through the hole provided in the plate-shaped member passes through the plate-shaped member notch and hits the baffle plate in the direction. The fluid whose flow rate has been changed is pushed further downstream to further reduce the momentum, and the fluid whose direction has changed by hitting the baffle plate is attracted by the vortex generated behind the baffle plate and diffused throughout the flow path, thus reducing uneven flow. .

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1 and 2 are a sectional view and an upper surface partial sectional view of an ultrasonic flow rate measuring apparatus according to a first embodiment of the present invention.

In FIG. 1, reference numeral 21 is an introduction passage of a fluid to be measured, which is composed of an inlet 22, an opening / closing valve 23 of an electromagnetic type or a stepping motor type, an opening / closing valve downstream side passage 24, and a fluid control means 25. Has been done. The on-off valve downstream side flow path 24 is on the downstream side of the valve seat opening 26 of the on-off valve 23 and has a rectangular cross-sectional shape. The fluid control means 25 is constituted by a plate-shaped member having a porosity in the direction of the flow path, a baffle plate, etc., and the size and distribution density of the holes are determined by the size of the flow path and the size of the flow rate. It is decided by the loss. On-off valve 23
The opening / closing center line of the opening / closing valve and the central axis of the opening / closing valve downstream side flow path 24 have an angle of about 90 degrees. Further, the valve seat opening 26 enters the flow path 24 on the downstream side of the open / close valve at the step 28 in order to reduce the mounting external dimension of the drive portion 27 of the open / close valve 23, and the valve seat opening 26 and the valve seat opening 26 are inserted. The space between the wall surface 29 and the wall surface 29 located at the opposite position is narrowed, and the flow passage cross-sectional area of this portion is reduced. The measurement path 30 includes a bending portion 31, a measurement flow path inlet 4, a rectifying means 32 provided at the measurement flow path inlet 4, the measurement flow path 1, and a discharge bending portion 33. The bent portion 31 is the introduction path 2
1 is connected to the on-off valve downstream side flow passage 24, has a rectangular cross section, and has a recess 34 on the wall surface facing the on-off valve downstream side flow passage 24.
Is provided. The measurement flow path 1 is substantially perpendicular to the central axis of the open / close valve downstream flow path 24 of the introduction path 21.

As described in the conventional example, the rectifying means 32 is a flow direction regulating means 7 composed of a partition plate inclined in a desired direction according to the turbulence of the flow, and a fluctuation restraint composed of a mesh having fine passages. And means 8.
The measurement flow path 1 has a rectangular cross section, and as shown in FIG. 2, a pair of ultrasonic transmitters / receivers 2, 3 are located upstream of the flow path on the wall surface in a direction perpendicular to the direction of the introduction path 21 with the flow path interposed therebetween. Side and downstream sides are diagonally opposed and mounted. Reference numeral 35 represents a rectified state of the fluid, and the flow velocity distribution in the flow path is represented in proportion to the length of the arrow. A discharge path 36 is connected to the discharge bending portion 33. The fluid to be measured flows out from the outlet 37 of the discharge path 36. The flow path 24 on the downstream side of the on-off valve, the measurement path 30, and the discharge path 36 of the introduction path 21 are U-shaped. Reference numeral 38 denotes a measurement control means which alternately transmits and receives ultrasonic waves between the ultrasonic transmitters / receivers 2 and 3 and measures the difference in the propagation time of the ultrasonic waves in the forward direction and the backward direction with respect to the fluid flow at regular intervals. , Has a function of outputting as a propagation time difference signal. Further, 39 is a calculation means for receiving the propagation time difference signal from the measurement control means 38 and calculating the flow velocity and flow rate of the fluid to be measured. Further, 40 is a power supply means composed of a lithium battery or the like. The measurement control unit 38, the calculation unit 39, a part of the power supply unit 40, and the drive unit 27 of the opening / closing valve 23 are mounted in the space inside the flow path of the fluid to be measured which is formed in a U-shape.

The operation and action of the ultrasonic flow rate measuring device configured as described above will be described below. First, the fluid to be measured flows from the inflow port 22 of the introduction path 21 through an external pipe (not shown). Further, the open / close valve 23 is opened, passes through the valve seat opening 26, hits the opposing wall 29 of the downstream passage 24 of the on / off valve, changes direction, and forms a drift along the opposing wall surface 29 to the fluid control means 25. Go to This uneven flow has a short distance between the valve seat opening 26 and the wall surface 29, and the narrower the flow passage cross-sectional area, the faster the flow velocity. Since the holes of the fluid control means 25 generate a pressure loss proportional to the passage flow rate, they become a large resistance body against an excessive passage flow rate, and the uneven flow diffuses all over the surface on the upstream side of the fluid control means 25, It flows through the holes on the entire surface of the control means 25 to the downstream side. As a result, the uneven flow generated after passing through the on-off valve 23 is weakened and flows into the bent portion 31. At the bent portion 31, the flow direction can be changed by 90 degrees, so the flow along the outer wall of the flow path creates uneven flow, but it is bent toward the center of the flow path at the depression 34 and measured while mixing with the fluid passing through the center. It flows to the flow path inlet 4.

The rectifying means 32 provided at the measurement flow path inlet 4 restricts the flow direction to the same direction as the flow path by the flow direction restricting means 7, and makes the flow distribution uniform via the fine passages of the non-uniform flow suppressing means 8. To do. The fluid flowing through the measurement channel 1 flows in the rectified state 35 because the flow velocity near the wall surface is decelerated by the frictional resistance of the wall surface.
Further, the fluid flows out to an external pipe (not shown) via the discharge bending portion 33 and the discharge passage 36. Next, the ultrasonic wave transmitted from one of the pair of ultrasonic wave transmitters / receivers provided on the wall surface of the measurement flow path 1 is affected by the flow velocity of the fluid to be measured, and when the ultrasonic wave propagates in the forward direction, the ultrasonic wave flows quickly. When it propagates in the opposite direction, the signal is received by the other transceiver late. The transmission / reception of this ultrasonic wave is controlled by the measurement control means 38 so that the pair of ultrasonic wave transmitters / receivers 2,
Alternately performed between 3 and converted into an electric signal, and converted into an ultrasonic wave propagation time in the forward direction and the reverse direction of the fluid flow by the measurement control means 38. Since the propagation time difference is proportional to the fluid flow velocity, this is transmitted to the computing means 39. Computing means 3
Reference numeral 9 calculates the signal from the measurement control means 38, the cross-sectional area of the measurement flow path stored inside, and the coefficient peculiar to the device to calculate the flow velocity or flow rate of the fluid to be measured.

As described above, in the present embodiment, the fluid control means 25 is provided in the open / close valve downstream side flow path 24 of the introduction path 21 separated from the measurement flow path inlet 4, so that the valve seat opening of the open / close valve 23 is achieved. Since the action of suppressing the non-uniform flow generated in the partial flow path occurs, the flow of the fluid in the measurement flow path 1 can be improved, and the ultrasonic measurement device can be downsized and the measurement accuracy can be improved.

Further, in this embodiment, since the opening / closing valve 23 can be attached by narrowing a part of the opening / closing valve downstream side passage 24, the space inside the passage formed in a U-shape can be expanded. Since the measurement control means 38, the calculation means 39, the power supply means 40, etc. can be housed, it is useful for downsizing the ultrasonic flow rate measuring device.

Further, in the present embodiment, the open / close valve downstream side flow passage 2
4 is provided with the fluid control means 25, the bent portion 31 having the depression 34, and the rectifying means 32 provided at the measurement flow path inlet 4, so that the flow velocity is fluctuated at a short time interval due to the turbulence of the flow. The measurement flow path 1
It is possible to improve the flow of the fluid to be measured in the inside, shorten the flow path, and reduce the size of the ultrasonic measurement device and improve the measurement accuracy.

In the present embodiment, the rectifying means 32 is composed of both the flow direction regulating means 7 and the drift suppressing means 8, but it may have either one or the on-off valve 2.
The center axis of opening and closing of 3 is 90 degrees with the center axis of the flow path 24 on the downstream side of the on-off valve.
It may be configured to intersect at an angle other than degrees.

(Embodiment 2) FIG. 3 is a sectional view of a fluid control means of an ultrasonic flow rate measuring apparatus according to a second embodiment of the present invention. The other parts of the ultrasonic flow rate measuring device are the same as those in FIG. In FIG. 3, reference numeral 51 is a fluid control means composed of a plate-like member having porosity, which is an example of the fluid control means 25 in FIG. 1, and a hole 52 is provided on the entire surface of the plate-like member 51. The size of the holes 52 and the installation density are experimentally determined by the flow rate of the flow path and the size of the uneven flow.

In the ultrasonic flow rate measuring device configured as described above, the fluid to be measured which has passed through the valve seat opening 26 of the on-off valve 23 and collided with the facing wall 29 flows downstream along the wall surface, It hits the plate member 51. When the fluid passes through the hole 52 provided in the fluid control means 51, a passage resistance is generated, which prevents an excessive flow rate from flowing, so that the uneven flow is diffused along the upstream surface of the plate-shaped member 51 and the plate-shaped member 51 It flows through the holes provided on the entire surface in accordance with the fluid pressure, and a weak drift occurs on the downstream side of the plate member 51.

(Embodiment 3) FIG. 4 is a cross-sectional view showing a mounting state of a porous plate member 51 which is a fluid control means 25 of an ultrasonic flow rate measuring apparatus according to a third embodiment of the present invention. In FIG. 4, the point different from Example 2 is that the plate-like member 51 having porosity is obliquely attached so that the portion with strong drift is on the upstream side 61 and the portion with weak drift is on the downstream side 62. .

In the ultrasonic flow rate measuring device configured as described above, the fluid to be measured which has passed through the valve seat opening 26 of the on-off valve 23 and collided with the facing wall 29 flows downstream along the wall surface, It hits the upstream side 61 of the plate member 51. Then, the flow spreads downstream along the slope of the plate-shaped member 51 and flows downstream through the holes 52 provided in the plate-shaped member 51, resulting in extremely weak drift on the downstream side of the plate-shaped member 51. . As compared with the second embodiment, the uneven flow is more likely to spread over the entire upstream surface of the plate-shaped member 51 forming the fluid control unit 25.
The pressure loss in the plate member 51 is reduced, and the drift in the downstream side can be further reduced.

(Embodiment 4) FIG. 5 is a cross-sectional view showing the installation condition of the holes of the porous plate member 51 constituting the fluid control means 25 of the ultrasonic flow rate measuring apparatus of the fourth embodiment of the present invention. is there. In FIG. 5, the difference from the third embodiment is that the plate-shaped member 5
The size of the hole 52 of No. 1 is small on the upstream side 61, and the size of the downstream side 6
2 is a big point.

In the ultrasonic flow rate measuring device configured as described above, the upstream side 61 of the plate-like member 51 has the largest uneven flow, so that it has a large pressure and the passing fluid loss due to a large passing pressure loss of a small hole. The flow velocity is weakened and uneven flow is generated by the plate-shaped member 51.
In the plate-shaped member 51, since the flow of the partial flow gradually weakens due to the flow while branching into the holes 52 provided along the inclined surface of the plate 52, and the weak flow of the partial flow passes through the large holes on the most downstream side 62. The pressure loss is small, and the drift is extremely small on the downstream side of the fluid control unit 25.

(Embodiment 5) FIG. 6 is a cross-sectional view showing the installation condition of the holes of a porous plate member 51 used as the fluid control means 25 of the ultrasonic flow rate measuring apparatus of the fifth embodiment of the present invention. . In FIG. 6, the difference from the fourth embodiment is that the plate-shaped member 5
1 is that a non-hole portion 63 is provided on the upstream side 61.

In the ultrasonic flow rate measuring device configured as described above, the strong uneven flow generated in the flow path 24 on the downstream side of the on-off valve is caused by the non-perforated portion 63 of the hole of the plate member 51 on the slope of the plate member 51. Change in the direction along. This eliminates the leakage phenomenon of the uneven flow that occurs when there is a hole oriented in the direction of the strong uneven flow. Further, since the hole 52 is opened at an angle with the direction of the non-uniform flow, the non-uniformity of the flow-direction component force of the non-uniform flow that flows along the upstream surface of the plate-shaped member 51 in the portion where the hole 52 is present. Can be reduced and the non-uniformity of the fluid passing through the holes 52 can be improved, so that the drift in the downstream portion of the plate-shaped member 51 can be reduced.

(Embodiment 6) FIG. 7 is a sectional view showing the shape of a fluid control means 25 of an ultrasonic flow rate measuring apparatus according to a sixth embodiment of the present invention. In FIG. 7, the difference from the third and fourth embodiments is that the porous plate-shaped member 51 that constitutes the fluid control means 25.
The point is that the cutout portion 71 is provided on the downstream side 62.

In the ultrasonic flow rate measuring device configured as described above, when the flow rate flowing through the flow path is smaller than the size of the flow path, the uneven flow on the upstream side 61 of the plate-like member 51 is weak and the plate-like member is weak. Flows while appropriately branching into the hole 52 along the slope of the member 51, and residual uneven flow flows through the notch 71 at the tip of the downstream end of the plate-like member 51, thereby performing a non-uniform flow suppressing action with almost no passage pressure loss. I can do things.

(Embodiment 7) FIG. 8 is a sectional view showing the shape of a fluid control means 25 of an ultrasonic flow rate measuring apparatus according to a seventh embodiment of the present invention. In FIG. 8, the fluid control means 25 includes an eaves-shaped baffle plate 81 provided on a wall surface opposed to the wall surface 29 where uneven flow occurs, and an inclined side from the upstream side 61 with uneven flow to the downstream side 62 without uneven flow, and the downstream. The porous plate member 51 is provided with a cutout portion 71 at the tip of the side 62.

In the ultrasonic flow rate measuring device configured as described above, the drift generated upstream of the fluid control means 25 hits the upstream side 61 of the plate-shaped member 51 and changes the direction of the flow to change the direction of the plate-shaped member 51. It flows along the slope, and a part thereof sequentially passes through the holes 52 provided in the plate-shaped member 51 and flows downstream. The flow that could not be diverted to the hole 52 is the cutout 71.
Flow toward the center of the flow path through the baffle plate 81, but flow downstream without being biased by the flow passing through the hole 52. Further, a vortex is generated on the downstream side of the baffle plate 81, and is drawn by the vortex to spread the flow over the entire flow path, so that the strength of the non-uniform flow in the downstream of the fluid control means 25 is reduced to such an extent that there is no practical problem. It can be done.

[0040]

As described above, according to the present invention, it is possible to suppress and eliminate the strong drift that occurs near the valve seat opening of the on-off valve on the upstream side of the fluid control means. Since the function of the rectifying means provided at the inlet can be reinforced to rectify the fluid flowing in the measurement channel, the fluid channel can be shortened,
It is effective for downsizing the outer shape of the installation portion of the on-off valve, and it is possible to downsize the ultrasonic flow rate measuring device and improve its accuracy.

[Brief description of drawings]

FIG. 1 is a sectional view of an ultrasonic flow rate measuring device according to a first embodiment of the present invention.

FIG. 2 is a partially cutaway top view of the ultrasonic flow rate measuring device according to the first embodiment of the present invention.

FIG. 3 is a sectional view of a fluid control means portion of an ultrasonic flow rate measuring device according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a fluid control means portion of an ultrasonic flow rate measuring device according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a fluid control means portion of an ultrasonic flow rate measuring device according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view of a fluid control means portion of an ultrasonic flow rate measuring device according to a fifth embodiment of the present invention.

FIG. 7 is a sectional view of a fluid control means portion of an ultrasonic flow rate measuring device according to a sixth embodiment of the present invention.

FIG. 8 is a sectional view of a fluid control means portion of an ultrasonic flow rate measuring device according to a seventh embodiment of the present invention.

FIG. 9 is a top view of a rectifying unit and a measurement flow path of a conventional ultrasonic flow rate measuring device.

FIG. 10 is a sectional view of a flow path of a conventional ultrasonic flow rate measuring device.

FIG. 11 is an external view of a flow direction regulating unit of a conventional ultrasonic flow rate measuring unit.

[Explanation of symbols]

1 measurement channel A couple of ultrasonic transceivers 4 Measurement channel inlet 21 Introduction route 23 Open / close valve 24 Open / close valve downstream flow path 25 Fluid control means 32 rectifying means 38 measurement control means 39 computing means 51 plate member 52 holes 61 upstream side of plate member 62 Downstream of plate member 63 No hole 71 Notch 81 baffle

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Norio Niimura             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Yoshinori Inui             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 2F030 CA03 CE04 CF01 CF05 CF08                 2F031 AB09                 2F035 DA14

Claims (7)

[Claims] 1. An introduction path having an opening / closing valve and a fluid control means mounted in a downstream side passage of the opening / closing valve, and a bending means arranged at a rear end of the introduction path, and a rectifying means at an inlet portion thereof. From the measurement control means, and a measurement control means for measuring the propagation time of the ultrasonic wave between the ultrasonic transmitter-receiver, at least a pair of ultrasonic transmitter-receiver provided on the opposing wall surface of the measurement flow path An ultrasonic flow rate measuring device, comprising: an arithmetic means for calculating a flow rate based on the signal of. 2. The ultrasonic flow rate measuring device according to claim 1, wherein the fluid control means is a plate-like member which covers the introduction passage and has porosity in the direction of the passage. 3. The fluid control means is a plate-shaped member having a porosity that is inclined so that a portion having the strongest flow deviation in the flow path is on the upstream side and a portion having the weakest flow is on the downstream side. Ultrasonic flow rate measuring device. 4. The ultrasonic flow rate measuring device according to claim 3, wherein the fluid control means is a porous plate-like member having an opening area in which the passing pressure loss decreases toward the downstream side. 5. The ultrasonic flow rate measurement device according to claim 2, wherein the fluid control means is a plate-shaped member having no fluid passage hole in a portion of the flow path where the most uneven flow hits. 6. The ultrasonic flow rate measuring device according to claim 3, wherein the fluid control means is a plate-shaped member having a cutout portion in the downstream side portion where the drift is weakest. 7. The fluid control means is inclined such that the portion with the most uneven flow in the flow path is on the upstream side and the portion with the weakest flow is on the downstream side, and there is a notch in the downstream portion where the uneven flow is weak. The ultrasonic flow rate measuring device according to claim 1, comprising a plate-shaped member having porosity and an eaves-shaped baffle plate provided on the downstream side of the cutout portion.