JP2004093159A - Fixing device of straightening unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device of a straightening unit for preventing drift or disturbance of gas by fixing an included straightening element so as not to be deviated even when receiving a vibration or an impact from the outside to a detection part of a flowmeter. <P>SOLUTION: In this fixing device, the straightening unit 13 is installed in a first passage 12c provided in a housing 12, and a flow velocity sensor 3 is installed in a second passage 12d having a step 12e on the downstream of the first passage 12c and provided concentrically, and the straightening unit 13 is fixed on the first passage 12c. The device has a constitution equipped with a press means 18 mounted on the first passage 12c, for pressing and fixing the straightening unit 13 onto the step 12e. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rectifying unit fixing device that is installed upstream of a flow rate sensor in a detection unit of a flow meter and rectifies a gas flow.
[0002]
[Related background art]
When a flow rate sensor is used in a flow meter that measures the mass flow rate of a gas flowing through a flow path that is inserted into a flow path (pipe) of a fluid, for example, a gas, the drift or turbulence of the gas flowing in the flow path is 2. Description of the Related Art There has been known a flow meter capable of performing highly accurate measurement using a rectifying element having a wire mesh or a honeycomb structure. This flow meter is composed of a detection unit that performs gas rectification and sensing, and a conversion unit that performs signal processing, and a flow velocity sensor that detects the flow velocity, for example, a micro flow sensor, is attached to the inner wall of the flow path of the detection unit. The conversion unit calculates and displays the integrated flow rate, the instantaneous flow rate, and the like based on the signal from the micro flow sensor.
[0003]
FIG. 4 shows a configuration of a detection unit of a conventional flow meter using a flow rate sensor. The detection unit 1 includes a housing 2 provided with mounting flanges 2b at both ends of a pipe 2a forming a gas flow path. A flow rate sensor 3 for detecting gas flowing in the direction of arrow A, and a rectifying section 4 provided upstream of the flow rate sensor 3. The pipe 2a of the housing 2 is configured such that the inner diameter of the flow path 2c on the upstream side (left side in the figure) of the flow velocity sensor 3 is slightly larger than the inner diameter of the flow path 2d on the downstream side. A circular wire net 5, a cylindrical spacer 6, a honeycomb 7, a spacer 6, a circular wire net 8, and a cylindrical spacer 6 are sequentially housed and fixed by a C-ring 9. The flow rate sensor 3 is provided in a flow path 2d. Is installed. The wire nets 5 and 8 are drawn by dotted lines.
[0004]
[Problems to be solved by the invention]
When the detecting unit 1 having the rectifying unit 4 having the above structure receives vibration or impact from the outside, the wire nets 5, 8, the honeycomb 7, the spacer 6, and the like are deformed, or move in the flow channel, and move inside the flow channel. The flow of the gas may change due to a step with the (wall surface). If the flow of gas in the flow path changes, the reproducibility of the output of the flow meter cannot be maintained, and this is particularly fatal in a flow meter that performs actual flow calibration.
[0005]
In addition, when a micro flow sensor is used as the flow velocity sensor 3 and its detection unit is installed near the inner surface (wall surface) of the flow path to measure the flow velocity, if there is a step on the inner surface of the flow path, a vortex is generated at the step. And the reproducibility of the gas flow is lost.
The present invention has been made in view of the above points, and even when vibration or impact is externally applied to the detection unit of the flow meter, the built-in rectifying element is fixed so as not to be displaced and gas drift and turbulence are prevented. It is an object of the present invention to provide a rectifying unit fixing device that performs the above-described operation.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, a rectifying unit fixing device includes a rectifying unit installed in a first flow path provided in a housing, and a step formed downstream of the first flow path. A fixing device for installing a flow rate sensor in a second flow path provided concentrically and fixing the rectifying unit to the first flow path, wherein the fixing device is attached to the first flow path, It is characterized by comprising a pressing means for pressing the rectifying unit against the step to fix it.
[0007]
In the invention of claim 2, a female screw is provided on the inner peripheral surface of the opening of the first flow path, and the pressing means has a cylindrical shape, and is formed with a male screw on the outer peripheral surface to be screwed with the female screw. It is a cylindrical screw that is screwed into the flow passage and presses and fixes the rectifying unit.
The invention according to claim 3 is characterized in that the pressing means is further provided with a spring washer interposed between the cylindrical screw and the rectifying unit, and for pressing the rectifying unit elastically against the step.
[0008]
The rectifying unit is housed in the first flow path of the housing, and a cylindrical screw is screwed into the opening, and the rectifying unit is pressed against the step between the first flow path and the second flow path and fixed. This prevents the rectifying unit from shifting or moving in the first flow path even when the housing receives external vibration or shock, and the rectified fluid turbulently flows in the second flow path. Is prevented, and reproducibility of the measured value by the flow velocity sensor is ensured. By interposing a spring washer between the cylindrical screw and the rectifying unit to elastically press the rectifying unit against the step, loosening of the cylindrical screw due to vibration, impact, or the like is prevented.
[0009]
In the invention of claim 4, the rectification unit fixing device is provided with the rectification unit in the first flow path provided in the housing, and provided concentrically with a step downstream of the first flow path. A fixing device for installing a flow rate sensor in the second flow path, and fixing the rectifying unit to the first flow path, wherein the first flow path is divided in an axial direction to be detachable, The first flow path is provided with a spring washer for pressing and fixing the rectifying unit to the step, an annular groove is formed along both sides of the outer peripheral surface of the rectifying unit along the circumferential direction, and an O-ring is attached. The center of the rectifying unit is positioned and fixed to the center of one flow path.
[0010]
In the invention according to claim 5, the O-ring is formed of a rubber member.
In the invention according to claim 6, the O-ring is formed by a coil spring.
O-rings are attached to the outer peripheral surfaces on both sides of the rectifying unit, and the first flow path of the housing is divided and housed via a spring washer and then fixed. The rectifying unit is fixed by being pressed against a step between the first flow path and the second flow path by a spring force of a spring washer in the first flow path and O-rings mounted on both sides of the outer peripheral surface. As a result, the center is positioned and fixed at the center of the first flow path. This prevents the rectifying unit from shifting or moving in the first flow path even when the housing receives external vibration or shock, and the rectified fluid turbulently flows in the second flow path. Is prevented, and reproducibility of the measured value by the flow velocity sensor is ensured. The use of the rubber O-ring facilitates mounting of the rectifying unit on the first flow path. Further, by using an O-ring made of a coil spring, it is possible to prevent deterioration due to the fluid used.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a device for fixing a rectifying unit according to the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a first embodiment of a detection unit of a flow meter to which a fixing device for a rectification unit according to the present invention is applied.
As shown in FIG. 1, the detection unit 11 of the flow meter includes a housing 12, a flow sensor 3 installed in the housing 12, and a rectification unit 13 installed upstream (left side in the figure) of the flow sensor 3. In the housing 12, mounting flanges 12b are formed at both ends of a thick pipe 12a as a flow path, and the inside diameter of the first flow path 12c on one side (upstream side) from the approximate center is on the other side (downstream side). The second flow path 12d has a diameter slightly larger than the inner diameter of the second flow path 12d, is formed concentrically with a step, and a female screw 12f is engraved on the inner peripheral surface of the opening. The flow rectifying unit 13 is housed in the flow channel 12c, and the flow rate sensor 3 is installed at a position near the center of the flow channel 12d near the stepped portion 12e with its detection portion slightly projecting from the inner surface.
[0012]
The rectification unit 13 includes three circular wire meshes 14, 15, and 17 each having a cylindrical shape and different coarseness as rectification elements, and a honeycomb 16 including a plurality of (many) cells at predetermined intervals. It is arranged and integrally assembled to form a solid structure. The rectifying unit 13 can be inserted into the flow channel 12c, and has the same inner diameter as the inner diameter of the flow channel 12d.
[0013]
The cylindrical screw 18 as the pressing means has an inner diameter that is the same as the inner diameter of the flow path 12d and the rectifying unit 13, an outer diameter that can be inserted into the flow path 12c, and a female screw 12f on the outer peripheral surface of the opening 18a. A male screw 18c to be screwed is formed. Further, pin holes 18d are provided at both end positions of the diameter on the end face of the opening 18a.
The rectifying unit 13 is housed in the flow channel 12c, and then the cylindrical screw 18 is inserted and the male screw 18c is screwed into the female screw 12f. The cylindrical screw 18 is rotated by fitting two corresponding pins (not shown) of a screwdriver jig into two pin holes 18d on the end face of the opening 18a. The cylindrical screw 18 advances rightward in the drawing with the rotation, and the end face of the opening 18b comes into contact with and pushes the end face 13a of the rectifying unit 13 to press the end face 13b of the rectifying unit 13 against the step 12e. Thereby, the rectification unit 13 is firmly fixed in the flow path 12c. The rectifying unit 13 and the cylindrical screw 18 have the same inner diameter as the inner diameter of the flow path 12d, and there is no step between the rectifying unit 13 and the inner surface of the flow path 12d. Thus, the rectification unit 14 is installed in the flow path 12c on the upstream side of the flow velocity sensor 3.
[0014]
Note that a ring-shaped spring washer (wave ring) having the same outer and inner diameters as the outer and inner diameters of the cylindrical screw 18 may be interposed between the rectifying unit 13 and the cylindrical screw 18 for tightening. By using this spring washer, loosening of the cylindrical screw 18 due to vibration or impact can be prevented. The spring washer is formed by continuously forming a corrugated portion as a spring portion along a circumferential direction on a ring of a thin plate having a spring property, and has a uniform spring property against compression in the axial direction.
[0015]
The rectification unit 13 is rigidly configured by integrally assembling wire meshes 14, 15, 17 and honeycombs 16 as rectification elements, and is fixed by being pressed into the flow channel 12c by the cylindrical screw 18, The rectifying unit 13 is prevented from being deformed or moved in the flow channel 12c even when it is subjected to vibration or shock from outside the housing 12. Thereby, the drift or turbulence of the gas in the flow path 12d is prevented, and the reproducibility of the flow meter is secured.
[0016]
FIG. 2 is a cross-sectional view showing a second embodiment of the detection unit of the flow meter to which the fixing device of the rectification unit according to the present invention is applied. The housing 22 of the detection unit 21 has two housings 23 and 24 having substantially the same shape. And these are connected to each other. In the housing 23, mounting flanges 23b are formed at both ends of a thick pipe 23a as a flow path, and the inside diameter of a flow path 23c on one side (downstream side) from the approximate center is equal to that of a flow path 23d on the other side (upstream side). The diameter is slightly larger than the inner diameter and is formed so as to form a step 23 e, and the flow path 23 c is a storage section for storing a part of the rectification unit 13.
[0017]
Similarly, in the housing 24, mounting flanges 24b are formed at both ends of a thick pipe 24a as a flow path, and the inside diameter of the flow path 24c on one side (upstream side) from the approximate center is the flow path on the other side (downstream side). The flow path 24c is formed as a storage part for storing the remaining part of the rectification unit 14, which is slightly larger than the inner diameter of 24d and is formed to have a step 24e. The inner diameters of the flow passages 23 d and 24 d of the housings 23 and 24 are the same as the inner diameter of the rectification unit 13. The inner diameters of the flow paths 23c and 24c are slightly larger than the outer diameter of the rectifying unit 14, and the sum of the lengths is set slightly longer than the length of the rectifying unit 14. Then, a first channel is formed by the channels 23c and 24c, and the channel 24d is a second channel. The flow rate sensor 3 has a detection portion provided at a position near a step 24 e of the flow path 24 d of the housing 24 so as to slightly protrude from the inner surface.
[0018]
On the other hand, annular grooves 13c are provided near both sides of the outer peripheral surface of the rectifying unit 13, and rubber O-rings 25 are mounted as elastic support members. The rectification unit 13 can be housed in the flow paths 23c and 24c via the O-rings 25 on both sides. The O-ring 25 fixes the rectifying unit 13 to the center of the flow channel as much as possible by utilizing the property of rubber, that is, the property of shrinking when the rectifying unit 13 is inserted into the flow channels 23e and 24e and stretching after the insertion. It is for.
[0019]
The above-described spring washer 26 and one side of the rectifying unit 13 are housed in the flow path 23c of the housing 23, and the other side of the rectifying unit 13 is housed in the flow path 24c of the housing 24. The flanges 23b and 24b are fastened and fixed by bolts 27. The rectifying unit 13 has one end 13a pressed against the step 23e via the spring washer 26 and the other end 13b pressed against the step 24e. That is, the rectification unit 13 is fixed to the center of the flow paths 23c and 24c by the O-rings 25 and 25 on both sides, and is fixed immovably in the axial direction by the spring force of the spring washer 26. Accordingly, even when vibration or impact is received from outside the housing 22, deformation, movement, and the like in the flow paths 23c and 24c of the rectification unit 13 are prevented.
[0020]
The flow rectifying unit 13 is fixed at the center of the flow paths 23c and 24c by an O-ring 25 having elasticity, and is prevented from moving in the axial direction by a spring washer 26. , 24c and the shaking of the processing accuracy of the flow straightening unit 13 can be absorbed. Therefore, the processing of these constituent members becomes easy, and the cost can be reduced.
[0021]
As a supporting member for supporting the rectifying unit 13 in the flow paths 23c and 24c, a metal coil spring as shown in FIG. The formed O-ring 28 may be used. Alternatively, as shown in FIG. 3B, a plurality of, for example, three short metal coil springs 29 are connected at equal intervals in the circumferential direction to form an annular shape. O-rings 30 supported at three locations on the circumference may be used.
[0022]
By using a metal coil spring as a support member for supporting the rectifying unit 13 in this manner, it is possible to use a gas that would be deteriorated by a rubber O-ring without deterioration. Further, a coil spring made of a material that is hardly deteriorated with respect to the gas to be used may be used, or a material subjected to a surface treatment or the like may be used.
[0023]
【The invention's effect】
As described above, according to the present invention, even when the housing receives external vibration or impact, the rectification unit is prevented from shifting or moving in the first flow path, and the rectified fluid is removed from the first flow path. The turbulent flow is prevented in the second flow path, and the reproducibility of the measurement value by the flow velocity sensor is secured (claims 1 and 4). In addition, a spring washer is interposed between the cylindrical screw and the rectifying unit to elastically press the rectifying unit against the step, thereby preventing the cylindrical screw from being loosened due to vibration, impact, or the like. 3).
[0024]
In addition, the rectifying unit housed in the divided first flow path is pressed against the step with a spring washer, and the O-ring is mounted on the outer peripheral surface of the rectifying unit for positioning, thereby easily and accurately positioning and fixing. It becomes possible. Further, the processing accuracy of the first flow path can be reduced, and the manufacturing cost can be reduced (claim 4).
[0025]
In addition, the use of a rubber O-ring facilitates the mounting of the rectifying unit to the first flow path (claim 5), and the use of a coil spring O-ring prevents deterioration due to the fluid used. (Claim 6).
[Brief description of the drawings]
FIG. 1 is a sectional view showing a first embodiment of a detection unit of a flow meter to which a fixing device for a rectification unit according to the present invention is applied.
FIG. 2 is a cross-sectional view showing a second embodiment of a detection unit of a flow meter to which the fixing device for a rectification unit according to the present invention is applied.
FIG. 3 is a view showing another embodiment of the support member shown in FIG. 2;
FIG. 4 is a cross-sectional view of a detection unit of a flow meter using a conventional flow rate sensor.
[Explanation of symbols]
3 Flow velocity sensors 11, 21 Detectors 12, 22, 23, 24 Housings 12c, 12d, 23c, 23d, 24c, 24d Flow path 13 Rectifying units 14, 15, 17 Wire mesh (rectifying element)
16 Honeycomb (rectifying element)
18 Cylindrical screw 25, 28, 29 O-ring (elastic support member)
26 Spring washer

Claims (6)

Installing a rectifying unit in a first flow path provided in the housing, installing a flow rate sensor in a second flow path concentrically provided with a step downstream of the first flow path, A fixing device for fixing a rectifying unit to the first flow path,
A fixing device for a rectifying unit, comprising: a pressing unit mounted on the first flow passage and pressing the rectifying unit against the step to fix the rectifying unit. A female screw is provided on the inner peripheral surface of the opening of the first flow path,
The pressing means is a cylindrical screw which is formed in a cylindrical shape and has an outer thread formed on an outer peripheral surface thereof to be screwed with the female screw, and is screwed to the first flow passage to press and fix the rectifying unit. The fixing device of the rectification unit according to claim 1. The rectifying unit according to claim 2, wherein the pressing means further includes a spring washer interposed between the cylindrical screw and the rectifying unit, and elastically presses the rectifying unit against the step. Fixing device. Installing a rectifying unit in a first flow path provided in the housing, installing a flow rate sensor in a second flow path concentrically provided with a step downstream of the first flow path, A fixing device for fixing a rectifying unit to the first flow path,
The first flow path is divided in the axial direction to be detachable,
A spring washer that presses and fixes the rectifying unit to the step in the first flow path is provided,
An annular groove is formed along the circumferential direction on both sides of the outer peripheral surface of the rectifying unit, an O-ring is mounted, and the center of the rectifying unit is positioned and fixed at the center of the first flow path. Unit fixing device. The fixing device according to claim 4, wherein the O-ring is formed of a rubber member. The fixing device for a rectifying unit according to claim 4, wherein the O-ring is formed by a coil spring.

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