WO2004025226A1

WO2004025226A1 - Straightening device

Info

Publication number: WO2004025226A1
Application number: PCT/JP2003/011095
Authority: WO
Inventors: Takashi Yao; Hiroshi Tamura; Kazumitsu Nukui; Mitsunori Komaki; Takashi Tashiro; Eiichi Oshima; Satoshi Ishitani
Original assignee: Yamatake Corporation; Tokyo Gas Co., Ltd.; Takenaka Seisakusho Co., Ltd.
Priority date: 2002-08-29
Filing date: 2003-08-29
Publication date: 2004-03-25
Also published as: CN100356142C; JP2004093170A; AU2003257601A8; DE10393177B4; CN1688871A; AU2003257601A1; DE10393177T5

Abstract

A straightening device (4) installed in a flow passage (10) formed by a pipe (2a) on the upstream side of a flow velocity sensor (3) of a flowmeter, comprising a first straightening net (8) disposed apart from the flow velocity sensor and a second straightening net (6) disposed close to the flow velocity sensor, wherein the first straightening net has meshes smaller than those of the second straightening net to exclude foreign matter included in fluid so as to prevent the second straightening net from being clogged by the foreign matter, and the flow of the fluid around the flow velocity sensor is stabilized by the straightening action of the second straightening net to prevent the measuring accuracy of the fluid sensor from being lowered by the disturbance of the flow of the fluid.

Description

Specification

Technical field

The present invention relates to a rectifier, and more particularly to a rectifier that stably rectifies gas flowing toward a detection element in a flow path in which a detection element provided in a flow meter is arranged. Landscape technology

A mass flow meter measures the flow rate of a fluid, for example, a gas flowing in a flow path defined by a pipe or the like. In general, a detection element, for example, a flow rate sensor, and a signal processing of an output signal of the flow rate sensor are performed. A conversion unit for calculating the flow rate. The conversion unit calculates the instantaneous flow rate by multiplying the flow rate represented by the sensor output signal by the known pipe cross-sectional area, and calculates the integrated value of the instantaneous flow rate.

In such a flow meter, if the gas flowing in the pipe has a drift or turbulence, the measurement accuracy of the flow rate sensor is reduced and an error occurs in the flow rate measurement. Therefore, a rectifying element such as a rectifying plate or a rectifying network is provided on the upstream side of the flow velocity sensor, and the rectifying element regulates the flow of gas toward the flow velocity sensor to prevent a reduction in measurement accuracy due to knitting flow or turbulent flow. It is known to

According to the flow meter equipped with the rectifying element, the gas flow around the flow velocity sensor can be stabilized, and the measurement accuracy can be prevented from deteriorating due to the drift or turbulence of the gas. However, some of the plurality of through passages (holes and meshes) provided in the rectifying element may be clogged. In some cases, a net for removing foreign matter is provided on the upstream side of the rectifying element. In this case as well, clogging due to relatively small foreign matter passing through the net for removing foreign matter occurs. In any case, if a part of the rectifying element is clogged, the rectifying action in each part of the rectifying element becomes uneven, and the flow of gas passing through the rectifying element to a detection element, for example, a flow rate sensor, is reduced. Disturbance occurs and the flow rate sensor However, there arises a disadvantage that the measurement accuracy of the measurement is reduced. Disclosure of the invention

An object of the present invention is to prevent clogging of a rectifying element due to a foreign substance contained in a fluid flowing in a flow path in which a detection element of a flow meter is arranged, to make a rectifying action of each part of the rectifying element uniform, An object of the present invention is to provide a rectifier capable of stabilizing a flow and maintaining good measurement accuracy of a detection element.

In order to achieve the above object, a rectifying device of the present invention includes a first rectifying element disposed upstream of a detection element of a flow meter in a flow path, and the first rectifying element and the detection element in the flow path. A second rectifying element disposed between the first rectifying element and a plurality of first through passages formed in the first rectifying element. It is characterized in that it is smaller than the flow passage area of the second through passage.

The fluid flowing in the flow path is first rectified by the first rectifying element of the rectifying device and then rectified by the second rectifying element to reach around the detection element of the flow meter. As described above, the rectifying device of the present invention performs the rectifying action in at least two stages to perform good rectification, stabilizes the flow of the fluid around the detection element, and performs detection by the turbulence of the fluid flow. A decrease in the measurement accuracy of the element is prevented.

If the fluid flowing in the flow path contains foreign matter, the foreign matter may be clogged by the foreign matter, and the flow of the fluid around the detection element downstream of the straightening element may be disturbed. In this regard, the rectifying device of the present invention eliminates foreign matters in the fluid by the first rectifying element, prevents clogging of the second rectifying element, and prevents disturbance of the fluid flow. That is, foreign matter having a size larger than the flow passage area of the first through passage is captured by the first rectifying element and does not flow to the second rectifying element. Foreign matter having a size smaller than the flow passage area of the first through passage passes through the first rectifying element and flows toward the second rectifying element with the flow of the fluid. The passage area of the passage is larger than that of the first through passage of the first rectifying element, The object also passes through the second rectifying element.

As described above, the first rectifying element having both the rectifying function and the foreign matter removing function is arranged upstream of the second rectifying element in the fluid flow direction, and the first rectifying element prevents the second rectifying element from being clogged. I am trying to do it. Certainly, the first rectifying element may be clogged due to the removal of foreign matter from the first rectifying element, so that the rectifying action of the first rectifying element may be non-uniform. Fluid flowing into the second rectifying element downstream of the element does not contain a large foreign matter that may clog the second rectifying element, and therefore, the risk of clogging the second rectifying element is extremely reduced. As a result, a uniform rectifying action is exerted by the second rectifying element upstream of the detecting element, so that the flow of fluid around the detecting element is stabilized, and the measurement accuracy of the detecting element is reliably prevented from lowering. You. As a result, even in a measurement environment with many foreign substances such as dust, the flow rate measurement can be performed reliably and stably. In the present invention, the first and second rectifying elements can be variously configured, and for example, can be configured by the first and second rectifying networks. The first and second rectification networks have a plurality of first meshes and a plurality of second meshes respectively corresponding to the plurality of first and second through passages, and the size of each first mesh is the size of the second mesh. It is smaller than the mesh size. The first and second rectification networks can be made of various materials in various shapes. For example, the first and second rectification networks are made of a metal material or a synthetic resin material in a square or hexagonal shape.

In the present invention, one or more intermediate rectifying elements (for example, rectifying networks) may be arranged between the first rectifying element and the second rectifying element, and the plurality of through passages provided in the intermediate rectifying element The area is larger than the flow passage area of the plurality of first through passages of the first rectifying element, and preferably smaller than the flow passage area of the plurality of second through passages of the second rectification element. According to this preferred embodiment, not only the rectifying action is exerted by the intermediate rectifying element, but also the clogging of the second rectifying element arranged near the detecting element is more reliably caused by the intermediate rectifying element. Since it is prevented, the measurement accuracy can be further improved. The rectifying device of the present invention is arranged in an environment in which fluid flows in the flow path in both directions. The present invention is also applicable to a flow meter provided with a detection element. In this case, the rectifying device of the present invention further includes third and fourth rectifying elements arranged on the opposite side of the detection element in the flow path from the first and second rectifying elements, and the fourth rectifying element includes the fourth rectifying element. The plurality of third through passages, which are arranged closer to the detection element than the third rectification element and are formed in the third rectification element, are flow paths of the plurality of fourth through passages formed in the fourth rectification element. It is characterized by having a flow passage area smaller than the area.

In this preferred embodiment, when the fluid flows through the first and second rectifying elements toward the sensing element, as described above, relatively large foreign objects are captured by the first rectifying element while the first rectifying element. Small foreign matter passing through the element also passes through the second rectifying element, so that clogging of the second rectifying element is prevented. When the fluid flows in the opposite direction, since the flow passage area of the third through passage of the third rectifying element is smaller than the flow passage area of the fourth through passage of the fourth rectifying element, a large foreign substance is occupied by the third rectifying passage. Small foreign objects trapped by the element and passing through the third rectifying element also pass through the fourth rectifying element, and therefore there is little risk of the fourth rectifying element becoming clogged. In this way, the second and fourth rectifying elements disposed on both sides of and near the detecting element are prevented from being clogged, so that the second and fourth rectifying elements exert a uniform rectifying action, and therefore, the detection is performed. Fluid flow around the element is stable irrespective of the flow direction of the fluid, and the measurement accuracy of the detection element is well maintained.

Further, a flow meter used together with the rectifier of the present invention is configured as a mass flow meter having a flow rate sensor as the detection element and a conversion unit for processing an output signal of the flow rate sensor to obtain a flow rate of the fluid. be able to. ADVANTAGE OF THE INVENTION The rectifier of this invention can stabilize the fluid flow around a flow velocity sensor, and can prevent the measurement precision fall of the flow velocity sensor resulting from the disturbance of the fluid flow. That is, the rectifier of the present invention is particularly suitable for a mass flow meter. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic sectional view of a flow meter provided with a rectifier according to a first embodiment of the present invention,

FIG. 2A is a schematic front view showing a first rectifier network provided in the rectifier of FIG. 1, FIG. 2B is a schematic front view of an intermediate rectifier network provided in the rectifier,

FIG. 2C is a schematic front view showing a second rectifier network of the rectifier,

FIG. 3 is a schematic diagram showing a rectifier according to a second embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a rectifier according to a first embodiment of the present invention will be described with reference to FIG. 1 and FIG.

As shown in FIG. 1, a detecting section 1 of a mass flow meter comprises a housing 2 and a thick pipe 2a having a circular cross section, and a detecting element mounted on the pipe 2a, for example, a flow sensor 3 And The pipe 2a has an upstream pipe half 2c and a downstream pipe half 2d having a slightly smaller inner diameter than the upstream pipe half 2c. 2e are formed integrally with each other. Two pipes (not shown) are connected to both ends of the pipe 2a. Reference 2b indicates a flange that is provided for such a pipe connection.

The flow velocity sensor 3 extends radially through the wall of the downstream pipe half 2 d near the step 2 e of the pipe 2 a to form a flow path 10 defined by the inner peripheral surface of the pipe 2 a. It has a detection end 3a disposed in front of it, and measures the flow velocity of a fluid, for example, a gas flowing in the flow path 10. In addition to the flow rate sensor 3, the mass flow sensor calculates the instantaneous flow rate of the fluid by processing the output signal of the sensor 3 and calculates the instantaneous flow rate. And a display unit 12 for displaying the calculated value of the integrated flow rate.

The rectifier 4 is disposed on the inner surface of the upstream pipe half 2 c and is fixed to the pipe 2 a by fixing means 5. That is, the rectifier 4 is viewed in the fluid flow direction. And is fixedly arranged on the upstream side of the flow velocity sensor 3.

Specifically, the rectifying device 4 includes three rectifying networks 6 to 8 and three spacers 9, and the rectifying networks 6 to 8 are made of, for example, a metal material. Since the pipe 2a has a circular cross section, each straightening net 6 to 8 is formed in a circular shape, and each spacer 9 is formed in a cylindrical shape. Further, for example, a cylindrical screw is used as the fixing means 5.

The flow straightening networks 6 to 8 are supported by the spacer 9 and the stepped portion 2e of the pipe 2a, and are arranged in the pipe 2a at intervals in the fluid flow direction. The outer diameters of the straightening networks 6 to 8 and the spacer 9 are substantially the same as the inner diameter of the upstream pipe half 2c, and the inner diameter of the spacer 9 is substantially the same as the inner diameter of the downstream pipe half 2d. It is the same, so that the fluid flow in the pipe 2a is not disturbed by the rectifier 4 installed on the inner surface of the pipe.

The flow rectification network 6 has a large number of rectangular meshes, and each mesh defines a rectangular through passage (one of which is denoted by reference numeral 6a) through which the fluid passes. Similarly, the flow straightening networks 7, 8 have a large number of meshes defining through passages 7a, 8a. On the other hand, as shown in FIGS. 2A to 2C, the mesh size of the rectification network 6 (that is, the flow passage area of the through passage 6a defined by each mesh) is It differs from the mesh size of 7 and 8.

Specifically, the upstream rectification network (first rectification network) 8 located far from the flow velocity sensor 3 as viewed in the longitudinal direction of the pipe 2a is, for example, 100 mesh (the number of meshes per inch is 100). The downstream rectifying network (second rectifying network) 6 located near the flow velocity sensor 3 has the largest mesh size of, for example, 40 mesh. The mesh size of the intermediate rectification network 7 disposed between the first rectification network 8 and the second rectification network 6 is, for example, 60 mesh, which is larger than the mesh size of the first rectification network 8 and the second rectification network 8. Smaller than the mesh size of

The rectifier networks 6 to 8 act to regulate the flow of the fluid when the fluid passes through a number of meshes provided in each rectifier network. Generally, the smaller the mesh size, the stronger the rectifying action. On the other hand, the pressure loss also increases, so the mesh size is appropriately determined in consideration of the rectifying action and the degree of the pressure loss.

The cylindrical screw 5 has a male screw 5c formed on the outer peripheral surface thereof, and can be screwed to the inner peripheral surface of the pipe 2a with the female screw 2f. Further, for example, two pin holes 5 d are formed in the annular end face 5 a of the cylindrical screw 5 so that the cylindrical screw 5 can be screwed to the pipe 2 a using the pin hole 5 d as described later. . The inner diameter of the cylindrical screw 5 is substantially the same as the inner diameter of the downstream pipe half 2 d and the inner diameter of the spacer 9.

Hereinafter, an assembling procedure of the rectifier 4 will be described.

When assembling the rectifier 4, first, the second rectifier network 6, the first spacer 9, the intermediate rectifier network 7, the second spacer 9, the first rectifier network 8, and the The three screws 9 are stored in this order, and then the cylindrical screw 5 is rotated using an instrument (not shown) having a pin fitted into the pin hole 5 d of the cylindrical screw 5. The cylindrical screw 5 advances inside the pipe 2a as it rotates, and its inner end face 5b contacts the third spacer 9 and the second rectifier net 6 presses against the step 2e of the pipe 2a. Leads to. The second rectifier net 6 is fixed with its peripheral edge sandwiched between the pipe step 2 e and the first spacer 9, and the rectifier nets 7, 8 also have their peripheral edge sandwiched between the spacers 9. And fixed. In this way, the rectifying networks 6 to 8 and the spacer 9 of the rectifying device 4 are fixed in the upstream pipe half 2c so as not to move in the axial direction. That is, the rectifying device 4 is installed in the pipe 2 a on the upstream side of the flow velocity sensor 3. Since the inner diameter of the spacer 9 is substantially the same as the inner diameter of both pipe halves 2c and 2d, there is no large step between the inner surface of the spacer and the inner surface of the pipe. Fluid flows smoothly inside.

Note that a ring-shaped spring washer (a waping ring) having substantially the same inner diameter and outer diameter as the cylindrical screw 5 may be interposed between the rectifier 4 and the cylindrical screw 5. The spring washer is formed by forming a spring-like thin plate into a corrugated shape in the circumferential direction, and exhibits a uniform spring property with respect to compression in the axial direction. Therefore, the panel By using the shears, the loosening of the cylindrical screw 5 due to vibration or impact can be prevented.

Hereinafter, the operation of the rectifier 4 will be described.

In FIG. 1, reference numeral A indicates a flow direction of a fluid, for example, a gas flowing in a flow path 10 defined by the pipe 2a. That is, the gas supplied to the pipe 2 a via a pipe (not shown) is sequentially rectified by the first rectification network 8, the intermediate rectification network 7, and the second rectification network 6, and reaches around the flow velocity sensor 3. As described above, the rectifying operation is performed in three stages, so that the gas flow around the flow velocity sensor 3 is stabilized, and the measurement accuracy of the flow rate sensor 3 due to turbulence is prevented.

When foreign matter, such as dust, is contained in the gas flowing through the flow path 10, dust having a size larger than the mesh size of the first rectification network 8 is blocked by the first rectification network 8, and It does not flow downstream of the rectification network 8. Further, dust having a size smaller than the mesh size of the first rectifier net 8 flows through the first rectifier net 8 toward the intermediate rectifier net 7 on the gas flow. Is larger than that of the first rectification network 8, so that dust that has passed through the first rectification network 8 also passes through the intermediate rectification network 7. For the same reason, dust that has passed through the intermediate rectifier network 7 also passes through the second rectifier network 6.

As described above, relatively large dust is removed from the gas by the first rectification network 8, so that the gas flowing into the rectification networks 7, 6 downstream of the first rectification network 9 is clogged with the rectification networks 7, 6. It does not contain dust that is large enough to cause the rectification networks 7, 6 to be clogged. Therefore, a uniform rectifying action is exerted by the rectification networks 7 and 6, and the gas flow around the flow velocity sensor 3 is stabilized. Therefore, the flow velocity sensor 3 accurately measures the instantaneous flow velocity of the gas flowing in the flow path 10. The output signal of the flow velocity sensor 3 is sent to the converter 11, and the converter 11 multiplies the instantaneous flow rate represented by the sensor output signal by the cross-sectional area of the flow path 10 to obtain the instantaneous flow of the gas flowing through the flow path 10. Find the flow rate, add the instantaneous flow rate to the integrated flow rate, Find the flow rate. Then, the instantaneous flow rate and the integrated flow rate are displayed on the display unit 12.

In the rectifier 4, the rectifier networks 6 to 8 and the spacer 9 are pressed and fixed to the inner peripheral surface of the pipe 2a by the cylindrical screw 5, so that even when vibration or impact is applied to the housing 2 from the outside, In addition, the deformation and displacement of the flow regulating networks 6 to 8 and the spacer 9 are reliably prevented, and the drift and turbulence of the gas flowing in the flow path 10 are prevented. Also in this regard, the rectifier 4 contributes to preventing the measurement accuracy of the flow meter from being reduced.

Hereinafter, a rectifier according to a second embodiment of the present invention will be described with reference to FIG. The rectifying device 4 ′ of the second embodiment is applied to a mass flow meter provided with a flow rate sensor 3 arranged in an environment in which a fluid flows bidirectionally in a flow path. It has substantially the same basic configuration as the rectifier 4 according to the first embodiment shown in FIG. 1 except that rectification networks are provided on both sides. Therefore, FIG. 3 shows only the positional relationship of the rectifier networks 6, 8, 6 ′, 8 ′ with respect to the flow velocity sensor 3.

As shown in FIG. 3, the rectifying device 4 ′ includes first and second rectifying networks for adjusting the flow of a fluid, for example, a gas flowing in the direction of arrow A in the flow path corresponding to the flow path 10 in FIG. 8 and 6 and have the same configuration as the rectifier 4 in FIG. 1 in this respect. However, unlike the rectifier 4, the rectifier 4 'does not include the intermediate rectifier network 7. The first and second rectification networks 8 and 6 are each formed in an elliptical shape, and the mesh sizes of both are 100 mesh and 60 mesh, for example.

The rectification device 4 ′ further includes third and fourth rectification networks 8 ′ and 6 ′ for adjusting the flow of the fluid flowing in the flow path in the direction of arrow B. The third rectification network 8 ′ is disposed in the flow path on the opposite side of the first rectification network 8 with respect to the flow velocity sensor 3, and is preferably symmetric with respect to the position of the first rectification network 8 with respect to the flow velocity sensor 3. Placed in position. Further, the fourth rectification network 6 ′ is disposed on the opposite side of the flow velocity sensor 3 from the second rectification network 6 in the flow path, preferably, at a position symmetrical to the arrangement position of the second rectification network 6. The third rectifying network 8 ′ has a mesh size smaller than that of the fourth rectifying network 6. I have. In the second embodiment, the mesh size of the third and fourth rectifier networks 8 ', 6 is the same as that of the first and second rectifier networks 8, 6, for example, 100 mesh and 60 mesh. It is.

The operation of the rectifier 4 ′ is substantially the same as that of the rectifier 4. That is, when a fluid, for example, a gas flows in the direction of arrow A toward the flow rate sensor 3 through the first and second rectification networks 8 and 6, relatively large foreign matter, for example, dust, flows through the first rectification network 8. On the other hand, the small dust passing through the first rectification network 8 also passes through the second rectification network 6, so that the clogging of the second rectification network 6 is prevented. When gas flows in the direction of arrow B, large dust is trapped by the third rectifier 8 'because the mesh size of the third rectifier 8' is smaller than that of the fourth rectifier 6 '. The small dust passing through the third rectification network 8 ′ also passes through the fourth rectification network 6 ′, and therefore, there is little possibility that the fourth rectification network 6 ′ becomes clogged. Therefore, since the second and fourth rectification networks 6, 6 'arranged on both sides of the flow velocity sensor 3 provide a uniform rectification action, the gas flow around the flow velocity sensor 3 is stable regardless of the flow direction. Thus, the measurement accuracy of the flow rate sensor 3 is maintained well, and a good flow rate measurement can be performed by the flow meter.

The present invention is not limited to the above first and second embodiments, and can be variously modified. For example, in the first and second embodiments, a circular or elliptical rectification net is used, but the rectification net can be formed in various shapes according to the cross-sectional shape of the flow path. Further, in the embodiment, a rectifying net made of a metal material and having a square mesh is used.However, the material and the mesh shape of the rectifying net are not limited to this.For example, the rectifying net is made of a synthetic resin material. You may. Further, the mesh size described in both embodiments is an example, and is not limited to such a mesh size.

In the first embodiment, one intermediate rectification network is provided between the first rectification network on the upstream side and the second rectification network on the downstream side. However, two or more intermediate rectification networks may be provided. Alternatively, the intermediate rectification network may be removed. Also, the mesh size of the intermediate rectification network is It is not essential to make it smaller than this, and an intermediate rectification network having a mesh size equal to or larger than the mesh size of the second rectification network may be used.

In the second embodiment, the third and fourth rectification networks are provided at positions symmetrical to the arrangement positions of the first and second rectification networks with respect to the flow velocity sensor. (2) It is not essential to arrange the symmetrical position with the rectification network. Also, in the second embodiment, one or more intermediate rectification networks may be provided between the first rectification network and the second rectification network or between the third rectification network and the fourth rectification network.

Furthermore, in the first and second embodiments, a rectifying network is used as a rectifying element. However, other rectifying elements, for example, a rectifying plate having a large number of small-diameter through holes as through passages through which a fluid passes are replaced with a rectifying network. May be used.

In other respects, the present invention can be variously modified. For example, it is not essential to use a cylindrical screw or a spacer when fixing the rectifier in the pipe.

Claims

The scope of the claims

1. A first rectifying element disposed upstream of the detection element of the flow meter in the flow path, and a first rectification element disposed between the first rectification element and the detection element in the flow path.

With two rectifying elements,

The rectifier is characterized in that the flow passage area of the plurality of first through passages formed in the first rectification element is smaller than the flow passage area of the plurality of second through passages formed in the second rectification element. apparatus.

2. The first and second rectifying elements include a first rectifying network having a plurality of first meshes corresponding to the plurality of first through passages, and a plurality of first rectifying networks corresponding to the plurality of second through passages. Each is composed of a second commutation network having a second mesh,

2. The rectifier according to claim 1, wherein the size of each of the first meshes is smaller than the size of each of the second meshes.

3. It further comprises one or more intermediate rectifying elements disposed between the first rectifying element and the second rectifying element,

The rectifying device according to claim 1, wherein the flow passage area of the plurality of through passages provided in the intermediate rectifying element is larger than the flow passage area of the plurality of first through passages of the first rectifying element. .

4. The flow passage area of the plurality of through passages provided in the intermediate rectifying element is smaller than the flow passage area of the plurality of second through passages of the second rectification element. Rectifier.

5. The apparatus further comprises third and fourth rectifying elements disposed on the opposite side of the detection element from the first and second rectifying elements in the flow path,

The fourth rectifying element is arranged closer to the detection element than the third rectifying element, and the plurality of third through passages formed in the third rectifying element are arranged in the plurality of fourth rectifying elements. 2. The rectifying device according to claim 1, wherein the rectifying device has a passage area smaller than a passage area of the fourth through passage.

6. The method according to claim 1, wherein the mass spectrometer is applied to a mass flow meter having a flow rate sensor serving as the detection section and a conversion section for processing a signal output from the flow rate sensor to obtain a flow rate of a fluid. A rectifier as described.