JPH11211523A - Fluid vibration type flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make each of pressure leading-out holes simply connectable with a pressure detecting means, and improve the maintainability and yield. SOLUTION: This fluid vibration type flowmeter detects a flow rate on the basis of fluid vibration of a jet jetting from a nozzle channel 210 to a downstream side channel 220. In a wall part (bottom wall part) 11 constituting the downstream side channel 220, pressure leading-out holes 4 are formed which penetrate the wall part 11 and reach one side and the other side of the jet. Each of the pressure leading-out holes 4 is detachably installed on the outer surface (contact surface) 11a of the wall part 11 and connected with a pressure detecting means via a pressure leading-out member 91.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid vibration type flowmeter for detecting a flow rate from a fluid vibration of a jet generated at a position near a nozzle flow path outlet of a two-dimensional flow path.

[0002]

2. Description of the Related Art As this type of fluid vibration type flowmeter, for example, the one shown in FIG. 25 is known. The fluid vibration type flowmeter FM shown in this figure has a pair of nozzle members 2 and 2 provided in a housing 1 closed by a cover 5.
A nozzle flow path 210 is formed in the housing 1, and an upstream flow path 200 and a downstream flow path 220 are formed upstream and downstream of the nozzle flow path 210, respectively. The downstream flow path 220 includes the nozzle flow path 2
The target 3 is provided on an extension of 10 (on the center line C). The gas (fluid) ejected through the nozzle flow path 210 collides with the target 3 to generate fluid vibration, and the principle is to detect the flow rate based on the fluid vibration.

The housing 1 is formed by a box-shaped rectangular groove 1a formed in a concave shape. By covering the surface of the groove 1 a with the cover 5, a two-dimensional flow path including the upstream flow path 200, the nozzle flow path 210, and the downstream flow path 220 is configured. That is, the upstream flow path 2
00, the nozzle flow path 210 and the downstream flow path 220
The height (dimension in the thickness direction perpendicular to the paper surface of FIG. 25) from the reference surface 10 which is the bottom surface of “a” is constant, and forms a bilaterally symmetric two-dimensional flow path via the center line C. . further,
The housing 1 is configured so that it can be connected to another flow path via the inlet 1b and the outlet 1c. The housing 1 has a screw hole 1e for fixing the cover 5 and a screw hole (not shown) for fixing the nozzle member 2. A bolt 6 for fixing the cover 5 is screwed into the screw hole 1e. The nozzle member 2 has a through hole 2 a through which the bolt 6 passes, and a through hole 2 b of a bolt 7 for fixing the nozzle member 2 to the housing 1.

The housing 1 has a downstream flow path 22.
Two pressure extraction holes 4 are provided on one side and the other side of the jet jetting out to zero and at a position equal in distance from the center line C. These pressure extraction holes 4 are shown in FIGS.
As shown in FIG. 8, the bottom wall of the housing 1 (downstream flow path 2
20).

As shown in FIG. 28, a pipe 81 is fixed to each pressure extraction hole 4 by welding or bonding.
These pipes 81 connect each pressure extraction hole 4 to a pressure sensor (pressure detecting means) not shown. Some pipes 81 are directly fixed to the pressure extraction hole 4 by a taper screw formed in the pipe 81 and the pressure extraction hole 4. The pressure sensor is
For example, a pressure difference between the pressures extracted from the two pressure extraction holes 4 is detected.
Fluid vibration of a jet ejected from zero is detected.

[0006] The fluid vibration type flowmeter FM measures the flow rate because the frequency of the fluid vibration is proportional to the flow rate or flow rate of the gas (fluid). The fluid vibration type flow meter FM measures the flow rate of the LP gas, and measures the fluid vibration of the LP gas. However, the fluid vibration type flow meter F having the above structure
In the case of M, it is also possible to measure the flow rate of a gas other than the LP gas or the liquid.

[0007]

However, in the above-mentioned fluid vibration type flow meter FM, the pipe 81 is connected to the pressure extraction hole 4.
However, in the case where the pressure fixing holes are fixed by welding or bonding, it takes time and labor to connect the pressure extracting holes 4 to the pressure sensors, which is troublesome.
Moreover, once the pipe 81 is fixed to the pressure extraction hole 4, there is a maintenance defect that the pipe 81 cannot be removed from the pressure extraction hole 4.

In the case where the pipe 81 is fixed to the pressure extraction hole 4 by a taper screw, the pipe 81 is usually screwed into the pressure extraction hole 4 of the main body fixed to a building or the like. The longer and bent the pipe 81 is, the more troublesome it is to connect each pressure extraction hole 4 to a pressure sensor. In addition, since the taper screw must be formed in each pressure extraction hole 4, if the processing fails, the housing 1
There is a disadvantage that the product itself becomes defective. That is, there is a disadvantage that the yield is poor.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to easily connect each pressure extraction hole to a pressure detecting means, and to improve a maintenance property and a yield in a fluid vibration. It is an object to provide a flow meter.

[0010]

In order to achieve the above object, according to the first aspect of the present invention, a flow rate is determined based on fluid vibration of a jet ejected from a nozzle flow path (210) to a downstream flow path (220). A fluid vibratory flowmeter configured to detect the flow rate, wherein the wall portion (1) constituting the downstream flow path (220) is
1) is provided with pressure extraction holes (4) penetrating through the wall portion (11) and reaching the one side and the other side of the jet, respectively, and each of the pressure extraction holes (4) is provided in the wall portion. (1
It is characterized in that it is connected to pressure detecting means via a pressure extracting member (91) detachably provided on the outer surface (11a) of 1).

According to a second aspect of the present invention, in the first aspect of the invention, one of the contact surfaces (11a, 91e) between the wall (11) and the pressure extracting member (91) is provided with a pressure extracting member. An O-ring groove (91f) formed annularly so as to surround each of the holes (4) and an O-ring (911) is provided in each O-ring groove (91f). 91e) to prevent the fluid from leaking to the outside, and to prevent the pressures captured by the respective pressure extraction holes (4) from affecting each other via the contact surfaces (11a, 91e). It is characterized by being.

According to a third aspect of the present invention, in the second aspect of the invention, each O-ring groove is formed in a figure-eight O-ring groove (11c) by sharing a part of each O-ring groove. Each of the O-rings also has a figure-eight O-ring (11) so as to fit into the figure-eight O-ring groove (11c).
It is characterized by being formed in 1).

[0013] The first aspect of the present invention is configured as described above.
In the invention according to the first aspect, each pressure extraction hole (4) is connected to pressure detection means via a pressure extraction member (91) detachably provided on the outer surface (11a) of the wall portion (11). Therefore, in order to connect each pressure extracting hole (4) to the pressure detecting means, for example, it is not necessary to fix a pipe to the pressure extracting hole (4) by welding or bonding, or to fix the pipe with a tapered screw. Therefore, each pressure extraction hole (4) can be easily connected to the pressure detecting means. In addition, the pressure take-out member (91) is connected to the wall (11)
Is removable from the outer surface (11a) of the
The maintainability can be improved. Furthermore, since it is not necessary to machine a tapered screw in each pressure extraction hole (4), no failure occurs due to this machining, and the yield can be improved.

In the invention according to claim 2, an O-ring groove (91f) formed in an annular shape so as to surround each of the pressure extraction holes (4) is provided, and an O-ring groove (91f) is provided in each O-ring groove (91f). Since the ring (911) is provided, it is possible to prevent the fluid from leaking to the outside from the portion of the contact surface (11a, 91e) between the wall (11) and the pressure extracting member (91). Moreover, each pressure extraction hole (4)
Can prevent each other from affecting each other via the contact surface (11a, 91e).
Fluid vibration of the jet can be accurately detected, and measurement accuracy of the flow rate can be improved.

According to the third aspect of the present invention, it is possible to prevent the following swells and the like. That is, when the pressure detected by each pressure extraction hole (4) is detected by the pressure detecting means as a pressure difference, for example, as shown in FIG. Ideally, B is obtained. But,
As shown in FIG. 22, a swelling phenomenon may occur in which the vibration waveform B is superimposed on the vibration waveform C having a lower frequency. When such undulations occur, the frequency of the vibration waveform B may not be able to be detected accurately.

Therefore, as a result of repeating various tests, the inventor of the present application found that the undulation was caused by the pressure extraction hole (4).
And found that the occurrence of undulation can be prevented by increasing the diameter of the pressure extraction hole (4).

However, when the diameter of the pressure extracting holes (4) is increased, the pressure extracting holes (4) come close to each other, so that the O-ring as described in the second aspect of the present invention. The groove (91f) and the O-ring (911) cannot be used. When a large O-ring groove and an O-ring are used to simultaneously surround the two pressure extraction holes (4), leakage of fluid to the outside can be prevented, but each pressure extraction hole (4) can be prevented. It is not possible to prevent the pressures caught in the above from affecting each other via the contact surfaces (11a, 91e).

That is, when the pressures in the respective pressure extraction holes (4) do not affect each other, for example, as shown in FIG. 23, a vibration waveform B that oscillates based on a pressure difference of 0 is obtained. However, when the pressures in the pressure extraction holes (4) affect each other, for example, as shown in FIG. 24, the amplitude D of the waveform B decreases, and when a slight pressure change (disturbance) occurs, the pressure is reduced. Since the signal does not cross the difference 0, the frequency of the vibration waveform B may not be detected accurately.

However, in the invention according to the third aspect, since the O-ring groove and the O-ring are formed by the figure-shaped O-ring groove (11c) and the O-ring (111), each pressure extraction hole is formed. The diameter of (4) is formed large, so that even if the pressure extraction holes (4) come close to each other, it is possible to prevent the pressures in the respective pressure extraction holes (4) from affecting each other. . Therefore, it is possible to prevent the vibration waveform of the jet flow obtained from each pressure extraction hole (4) from undulating or to reduce the amplitude D, and to improve the flow rate measurement accuracy.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on embodiments with reference to FIGS. In addition,
1 to 5 show a first embodiment, FIG. 6 shows a second embodiment, FIG. 7 shows a third embodiment, FIG. 8 shows a fourth embodiment, FIGS. 9 to 13 show a fifth embodiment, and FIGS. 17 is a sixth embodiment, FIG. 18 is another example of the pressure extraction member in each embodiment, and FIGS. 21 to 24 are explanatory diagrams showing examples of vibration waveforms.

First, a first embodiment will be described with reference to FIGS. However, components common to those of the conventional example shown in FIGS. 25 to 28 are denoted by the same reference numerals, and description thereof will be omitted.

The fluid vibration type flow meter FM shown in this embodiment
As shown in FIGS. 1 to 5, each pressure extraction hole 4 is connected to a pressure sensor (not shown) via a pressure extraction member 91 which is detachably provided on the outer surface 11 a of the bottom wall (wall portion) 11. Detection means).

As shown in FIGS. 3 to 5, the pressure take-out member 91 is formed in a rectangular parallelepiped shape, and has flanges 91a at its left and right ends for fixing to the bottom wall portion 11 with bolts BL. Are formed. Each flange 91a
Is provided with two holes 91b for inserting the bolts BL. A pressure relay hole 91c is formed at a position corresponding to each pressure extraction hole 4.

Each pressure relay hole 91c is provided with each pressure extraction hole 4
And have the same diameter. However, an enlarged diameter portion 91d is formed on the side of the pressure relay hole 91c opposite to the pressure extraction hole 4, and the pipe 81 is fitted into the enlarged diameter portion 91d and fixed by welding or an adhesive. .

In the pressure extracting member 91, an O-ring groove 91f is formed on a contact surface 91e that comes into contact with the outer surface 11a of the bottom wall portion 11, and an O-ring groove 91f is formed in the O-ring groove 91f.
A ring 911 is provided. Note that the outer surface 11 a of the bottom wall portion 11 is a contact surface that contacts the contact surface 91 e of the pressure extraction member 91.

The O-ring groove 91f is provided in each pressure relay hole 91c.
Are formed in a ring shape so as to surround each of the pressure take-out holes 4 as a result. The O-ring groove 91f and the O-ring 911 prevent gas (fluid) from leaking to the outside from the gap between the outer surface 11a and the contact surface 91e. The pressure of the gas transmitted to the pressure sensor via the pipe 81 is prevented from affecting each other via the gap between the outer surface 11a and the contact surface 91e.

In FIG. 2, 11b is a bolt B
L is a screw hole to be screwed. In FIG. 3, 4a
Is a detection hole for adjustment for adjusting the diameter of the pressure extraction hole 4 that opens to the downstream flow path 220.

In the fluid vibration type flow meter FM configured as described above, each pressure extraction hole 4 is provided with a pressure extraction member 9.
1 and a pressure sensor via a pipe 81, and a pressure extraction member 91 is connected to the bottom wall 11
Can be attached to and detached from the outer surface 11a, so that it is not necessary to fix the pipe 81 to the pressure extraction hole 4 by welding or bonding as shown in the conventional example, or to fix it by screwing it in. Can be.

That is, the pipe 81 and the pressure extracting member 9
1 is connected by welding or an adhesive, but since the pressure extracting member 91 is detachable from the bottom wall portion 11, each pressure extracting hole 4 can be easily connected to the pressure sensor. . Moreover, since the pressure extracting member 91 is detachable from the outer surface 11a of the bottom wall portion 11, maintenance can be improved. Furthermore, since it is not necessary to directly process the tapered screw into each pressure extraction hole 4, it is possible to prevent the entire housing 1 from becoming defective due to a defect in the processing. That is, the yield can be improved.

On the other hand, since the O-ring groove 91f and the O-ring 911 are provided so as to surround each of the pressure relay holes 91c, the gap between the outer surface 11a of the bottom wall portion 11 and the contact surface 91a of the pressure extracting member 91 is provided. Gas can be prevented from leaking from the outside. Moreover, since the pressures sensed by the respective pressure extraction holes 4 can be prevented from affecting each other via the outer surface 11a and the contact surface 91e, the fluid vibration of the jet can be accurately detected, The measurement accuracy of the flow rate can be improved.

Further, since the pressure take-out member 91 can be integrally formed by injection molding using a resin, even if the structure becomes complicated due to the O-ring groove 91f and the like, the manufacturing cost and the defective rate are reduced. Does not increase. Moreover,
By the injection molding, there is an advantage that the pressure extracting member 91 can be manufactured in large quantities and at low cost.

Next, a second embodiment of the present invention will be described with reference to FIG. However, components common to the components of the first embodiment shown in FIGS. 1 to 5 are denoted by the same reference numerals, and description thereof will be omitted. The difference between the second embodiment and the first embodiment is that
The point is that a tapered female screw portion 91g is formed instead of the enlarged diameter portion 91d.

That is, as shown in FIG. 6, a tapered female thread 91g is formed at the end of the pressure relay hole 91c on the side opposite to the pressure take-out hole 4, and a tapered female thread is formed at the end of the pipe 81. A tapered male screw portion 81a screwed with 91g is formed. The tapered female screw portion 91g and the tapered male screw portion 81a are hermetically connected by a seal tape.

In the fluid vibration type flow meter FM configured as described above, the pipe 81 and the pressure extracting member 91 are connected by a tapered screw. Each pressure outlet 4 can be easily connected to the pressure sensor because it is detachable.

That is, the portion of the main body side of the fluid vibration type flow meter FM is often installed in a building or the like as, for example, a gas meter. In this case, the operation of screwing the pipe 81 into the main body of the fluid vibration type flow meter FM is performed. The longer the pipe 81 is, and the more bent it is, the more difficult the work becomes. On the other hand, in the present embodiment, after the pipe 81 is screwed and fixed to the portion of the pressure extracting member 91 in advance, the pressure extracting member 91 is connected to the main body of the fluid vibration type flow meter FM, that is, the bottom wall 11 of the housing 1. Therefore, each pressure extraction hole 4 can be easily connected to the pressure sensor. Other effects are the same as those of the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIG. However, components common to those of the second embodiment shown in FIG. 6 are denoted by the same reference numerals, and description thereof is omitted. The third embodiment is different from the second embodiment in that the pipe 81 is connected to the pressure relay hole 91c via the joint member 912.

That is, the joint member 912 is a first joint 912a that is screwed and fixed to the tapered female screw portion 91g.
And a second joint 912b for fixing the pipe 81 to the first joint 912a with a cap nut or the like.

In the fluid vibration type flow meter FM configured as described above, the pipe 81 is connected to the pressure extracting member 91 via the joint member 912.
The pipe 81 can be connected to the pressure extracting member 91 without rotating the pipe 81 as in the second embodiment. Therefore, each pressure extraction hole 4 can be easily connected by the pressure sensor. In addition, the same effects as those of the first and second embodiments can be obtained.

Next, a fourth embodiment of the present invention will be described with reference to FIG. However, the same reference numerals are given to the same components as those of the third embodiment shown in FIG. 7, and the description is omitted. The fourth embodiment differs from the third embodiment in that a bamboo-shaped joint 913 is provided instead of the joint member 912.

That is, the joint 913 is fixed to the tapered female screw portion 91g via a tapered male screw portion 913a on the distal end side, and a hose (shown in FIG. Zu) to connect. The hose is connected to a pressure sensor (not shown).

In the fluid vibration type flow meter FM configured as described above, the pressure extracting member 91 and the pressure sensor can be connected very easily via a hose. Therefore, each pressure extraction hole 4 can be easily connected by the pressure sensor. In addition, the same effects as those of the first, second, and third embodiments are obtained.

Next, a fifth embodiment of the present invention will be described with reference to FIGS.
3 will be described. However, components common to those of the second embodiment shown in FIG. 6 are denoted by the same reference numerals, and description thereof is omitted. The fifth embodiment differs from the second embodiment in that the configurations of the O-ring groove and the O-ring are different.

That is, on the bottom surface 11a of the bottom wall 11,
As shown in FIG. 9, a figure-eight O-ring groove 11c is formed. The eight-shaped O-ring groove 11c is such that the O-ring groove surrounding the periphery of one pressure extraction hole 4 and the O-ring groove surrounding the other pressure extraction hole 4 share a part of each other. Are formed in a continuous shape in the shape of a figure eight. And, a figure-eight O-ring groove 11c
Is provided with a figure-eight O-ring 111 formed to fit into the O-ring groove 11c.

On the other hand, as shown in FIGS. 12 and 13, the pressure take-out member 91 has no O-ring groove and has a contact surface 91e.
Is an outer surface 11a of the bottom wall portion 11 and an O-ring 11 having a figure-shaped shape.
1.

The fluid vibration type flow meter FM configured as described above has an effect of preventing swelling and the like as described below. That is, when the pressure difference between the gases obtained from the two pressure extraction holes 4 is detected by the pressure sensor,
As shown in FIG. 21, it is ideal that a vibration waveform B that vertically oscillates with respect to a fixed reference value A is obtained.
As shown in FIG. 2, a swelling phenomenon may appear in which the vibration waveform B is superimposed on the vibration waveform C having a lower frequency. When such undulations occur, the frequency of the vibration waveform B may not be able to be detected accurately.

Therefore, as a result of repeating various tests, the inventor of the present application found that the waviness was related to the diameter of the pressure extraction hole 4, and in particular, the adjustment detection hole 4 a of the pressure extraction hole 4 was determined. It has been found that the swell can be prevented by increasing the diameter.

However, the diameter of the adjustment detection hole 4a is made to reach the diameter of the pressure extraction hole 4 and
In the case where the diameter of the pressure extraction hole is further increased, two pressure extraction holes 4
Are close to each other, so that an O-ring groove and an O-ring surrounding each pressure extraction hole 4 cannot be used. Therefore, it is conceivable to use an O-ring groove and an O-ring having such a size as to simultaneously surround the two pressure extraction holes 4 only in consideration of preventing gas leakage to the outside. However, in this case, although leakage of gas to the outside can be prevented, it is considered that the pressures captured by the respective pressure extraction holes 4 affect each other via the outer surface 11a and the contact surface 91e. It cannot be prevented.

When the pressures in the pressure outlets 4 do not affect each other, for example, as shown in FIG.
However, when the pressures in the pressure extraction holes 4 affect each other, for example, as shown in FIG. 24, the amplitude D of the waveform becomes low, and when the waveform is disturbed due to disturbance, the pressure difference becomes zero. Are not crossed, so that the frequency of the vibration waveform B cannot be accurately detected.

However, in this embodiment, since the O-ring grooves 11c and the O-rings 111 are formed in a continuous shape in a figure of eight, the pressure extraction holes 4 are made thicker by increasing the pressure extraction holes 4. Even when the holes 4 come close to each other, it is possible to prevent the pressures in the pressure extraction holes 4 from affecting each other. Therefore, it is possible to prevent the vibration waveform of the jet flow obtained from each pressure extraction hole 4 from undulating or to reduce the amplitude, and to improve the measurement accuracy of the flow rate. Also,
By forming each pressure extraction hole 4 as large as possible, the adjustment range of the adjustment detection hole 4a can be widened. Other effects are the same as those of the second embodiment.

Next, a sixth embodiment of the present invention will be described with reference to FIGS. However, components common to those of the fifth embodiment shown in FIGS. 9 to 13 are denoted by the same reference numerals, and description thereof is omitted. The sixth embodiment is different from the fifth embodiment in that an eight-shaped O-ring groove 11c is formed in the bottom wall 11.
And the O-ring 111 is provided on the pressure extracting member 91 side instead of being provided on the contact surface 91e of the pressure extracting member 91.

The fluid vibration type flow meter F constructed as described above
In the case of M, since the O-ring groove 11c is not formed in the bottom wall portion 11, it is possible to prevent the housing 1 from becoming defective due to a processing error in the O-ring groove 11c. That is, since the defective rate of expensive components can be reduced, manufacturing costs can be reduced after all. Further, since the pressure extracting member 91 can be integrally formed by injection molding using a resin,
Even if there is the ring groove 11c, the manufacturing cost and the defective rate do not increase. Moreover, the pressure extraction member 91 can be manufactured in large quantities and at low cost by injection molding. Other effects are the same as those of the fifth embodiment.

In each of the above-described embodiments, two holes 91b for inserting the bolts BL are provided in each flange 91a of the pressure extracting member 91.
As shown in FIGS. 18 to 20, one hole 91b may be provided at a central position in the vertical direction of each flange 91a.

Further, the pressure extracting member 91 is configured to be attached to the bottom wall portion 11 constituting the downstream flow path 220, but the cover (wall portion) 5 is provided with the above-described pressure extracting holes 4 and the pressure extracting member 91 is provided with the pressure extracting member 91. Pressure extracting member 91 is attached to cover 5
May be configured to be attached.

Further, in the fifth embodiment and the sixth embodiment, an example in which the pipe 81 is screwed and fixed to the pressure extracting member 91 (the same as that shown in the second embodiment) is illustrated. The connection structure between the member 91 and the pipe 81 (or hose) is described in the first embodiment.
It goes without saying that those shown in the third and fourth embodiments may be used.

[0055]

According to the first aspect of the present invention, each pressure extraction hole is connected to the pressure detecting means via a pressure extraction member detachably provided on the outer surface of the wall. In order to connect each pressure extracting hole to the pressure detecting means, for example, it is not necessary to fix a pipe to the pressure extracting hole by welding or bonding, or to fix the pipe by a tapered screw. Therefore, each pressure extraction hole can be easily connected to the pressure detecting means. In addition, since the pressure extracting member can be attached to and detached from the outer surface of the wall, maintenance can be improved. Furthermore, since it is not necessary to machine a tapered screw in each pressure extraction hole, failure due to this machining does not occur, and the yield can be improved.

According to the second aspect of the present invention, the annular O-ring groove is provided so as to surround each of the pressure extraction holes, and the O-ring is provided in each O-ring groove. Fluid can be prevented from leaking to the outside from a portion of the contact surface between the fluid and the pressure extracting member. Moreover, since the pressures sensed by the respective pressure extraction holes can be prevented from affecting each other via the contact surface portion, the fluid vibration of the jet can be accurately detected,
The measurement accuracy of the flow rate can be improved.

According to the third aspect of the present invention, it is possible to prevent the following undulations and the like. That is, when the pressure detected by each pressure extraction hole is detected by the pressure detecting means as, for example, a pressure difference, a vibration waveform B which oscillates up and down with respect to a fixed reference value A is obtained as shown in FIG. Is ideal. However, FIG.
As shown in FIG. 7, a swelling phenomenon may occur in which the vibration waveform B is superimposed on the vibration waveform C having a lower frequency. When such undulations occur, the frequency of the vibration waveform B may not be able to be detected accurately.

Therefore, as a result of repeating various tests, the inventor of the present application has found that the above-mentioned undulation depends on the diameter of the pressure extraction hole. In particular, by increasing the diameter of the pressure extraction hole, the undulation is improved. Can be prevented from occurring.

However, when the diameter of the pressure extraction hole is increased, these pressure extraction holes come close to each other, so that the O-ring groove and the O-ring as described in the second aspect of the present invention are used. Can not do it. Further, when a large O-ring groove and an O-ring are used to simultaneously surround the two pressure extraction holes, the leakage of the fluid to the outside can be prevented, but the pressure captured by each pressure extraction hole is in contact. It is not possible to prevent them from affecting each other via surface parts.

That is, when the pressures in the pressure extraction holes do not affect each other, a vibration waveform B that vibrates based on a pressure difference of 0 is obtained as shown in FIG. 23, for example. However, when the pressures in the pressure extraction holes affect each other, for example, as shown in FIG. 24, the amplitude of the vibration waveform becomes low, and when the waveform generated by disturbance or the like is disturbed, the pressure difference 0 is reduced. Since a crossing signal cannot be obtained, the frequency of the vibration waveform B may not be accurately detected.

However, according to the third aspect of the present invention, since the O-ring groove and the O-ring are formed by the eight-shaped O-ring groove and the O-ring, the diameter of each pressure extraction hole is increased. Thus, even if the pressure extraction holes come close to each other, it is possible to prevent the pressures in the pressure extraction holes from affecting each other. Therefore, it is possible to prevent the vibration waveform of the jet flow obtained from each pressure extraction hole from undulating or to reduce the amplitude, and to improve the measurement accuracy of the flow rate.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fluid vibration type flow meter shown as a first embodiment of the present invention, and is a sectional view taken along a line corresponding to line XXVI-XXVI of FIG.

FIG. 2 is a rear view of the fluid vibration type flow meter.

FIG. 3 is a sectional view of a main part of the fluid vibration type flow meter.

FIG. 4 is a plan view showing a pressure extracting member of the fluid vibration type flowmeter.

FIG. 5 is a bottom view showing a pressure extracting member of the fluid vibration type flowmeter.

FIG. 6 is a sectional view of a fluid vibration type flow meter shown as a second embodiment of the present invention, which is a sectional view taken along a line corresponding to line XXVI-XXVI in FIG.

FIG. 7 is a cross-sectional view of a fluid vibration type flow meter shown as a third embodiment of the present invention, and is a cross-sectional view at a position corresponding to line XXVI-XXVI in FIG.

FIG. 8 is a cross-sectional view of a fluid vibration type flow meter shown as a fourth embodiment of the present invention, and is a cross-sectional view at a position corresponding to line XXVI-XXVI in FIG.

FIG. 9 is a view of a fluid vibration type flow meter shown as a fifth embodiment of the present invention, and is a rear view of a main part showing an outer surface of a housing.

FIG. 10 is a cross-sectional view showing a bottom wall portion of a housing in the fluid vibration type flow meter, and is a cross-sectional view taken along line XX of FIG.

FIG. 11 is a plan view showing a figure-eight O-ring of the fluid vibration type flowmeter.

FIG. 12 is a bottom view showing a pressure extracting member of the fluid vibration type flow meter.

FIG. 13 is a sectional view showing a pressure extracting member of the fluid vibration type flow meter, and is a sectional view taken along line XIII-XIII in FIG.

FIG. 14 is a view of a fluid vibration type flow meter shown as a sixth embodiment of the present invention, and is a rear view of a main part showing an outer surface of a housing.

FIG. 15 is a cross-sectional view showing a bottom wall portion of a housing in the fluid vibration type flow meter, and is a cross-sectional view along the line XV-XV in FIG.

FIG. 16 is a bottom view showing a pressure extracting member of the fluid vibration type flow meter.

FIG. 17 is a cross-sectional view showing a pressure extracting member of the fluid vibration type flow meter, and is a cross-sectional view along the line XVII-XVII in FIG. 16;

FIG. 18 is a bottom view showing another example of the pressure extracting member shown in the first to fourth embodiments.

FIG. 19 is a bottom view showing another example of the pressure extracting member shown in the fifth embodiment.

FIG. 20 is a bottom view showing another example of the pressure extracting member shown in the sixth embodiment.

FIG. 21 is a diagram showing an ideal vibration waveform when a pressure difference between two pressure extraction holes is detected by a pressure detection unit.

FIG. 22 is a diagram showing a vibration waveform in a state where undulation has occurred when the pressure difference is detected by the pressure detecting means.

FIG. 23 is a diagram showing a vibration waveform in a case where the pressure difference is detected by the pressure detecting means and the pressures in the pressure extraction holes do not affect each other.

FIG. 24 is a diagram showing a vibration waveform in a case where the pressure difference is detected by the pressure detecting means and the pressures in the respective pressure extraction holes affect each other.

FIG. 25 is a front view of a fluid vibration type flow meter shown as a conventional example.

FIG. 26 is a sectional view showing the fluid vibration type flow meter,
26 is a cross-section along the line XXVI-XXVI of FIG. 25.

FIG. 27 is a rear view of the fluid vibration type flow meter.

FIG. 28 is a sectional view of a main part of the fluid vibration type flow meter.

[Explanation of symbols]

 Reference Signs List 4 pressure extraction hole 11 wall (bottom wall) 11a outer surface (contact surface) 11c 8-shaped O-ring groove 1 18 8-shaped O-ring 91 pressure extraction member 91e contact surface 91f O-ring groove 911 O-ring 210 Nozzle flow path 220 Downstream flow path FM Fluid vibration type flow meter

Claims (3)

[Claims] 1. A fluid vibratory flow meter configured to detect a flow rate based on fluid vibration of a jet ejected from a nozzle flow path to a downstream flow path, wherein a wall portion forming the downstream flow path Are provided with pressure extraction holes penetrating through the wall and reaching the one and the other sides of the jet respectively. The pressure extraction holes are detachably provided on an outer surface of the wall. A fluid vibratory flow meter characterized by being connected to pressure detecting means via a member. 2. An O-ring groove formed in a ring shape so as to surround each of the pressure extraction holes, on one of the contact surfaces between the wall portion and the pressure extraction member. An O-ring is provided to prevent leakage of fluid from the contact surface portion to the outside, and to prevent the pressures captured by the respective pressure extraction holes from affecting each other via the contact surface portion. The fluid vibration type flow meter according to claim 1, wherein: 3. Each of the O-ring grooves is formed into an eight-shaped O-ring groove by sharing a part thereof, and each of the O-rings is also fitted into the eight-shaped O-ring groove. 3. The fluid vibratory flow meter according to claim 2, wherein the flow meter is formed in an O-ring having a figure-eight shape.