JP2007121036A - Flowmeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flowmeter which can achieve stable measurement results and enlarge a measurement range. <P>SOLUTION: A space between an installation surface for a sensor 24 for measuring the flow of a fluid and a facing wall corresponding to the installation surface is formed as a sensor flow channel 121. A flow channel enlargement section 121a having a size c which is larger than a spacing size a between the installation surface for the sensor 24 and the facing wall is provided at a position other than the flow channel part at which the sensor 24 is positioned in the sensor flow channel 121. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flow meter for measuring a flow rate of a fluid, and more particularly to a flow channel structure thereof.

  Conventionally, as a flow meter that rectifies the flow of fluid in a flow path, for example, as shown in Patent Document 1, an inlet port and an outlet port are provided at both ends of a flow path portion, and these inlet ports A flow path is provided at right angles to the flow path of the outlet port, and the flow path in the flow meter is formed so that the flow path and the flow path where the flow sensor is located are at right angles. In some cases, a reproducible flow velocity distribution of the fluid was formed, and a stable measurement result was obtained.

Japanese Patent Laid-Open No. 2004-3877

  The conventional flow meter has an effect that a small and stable measurement result can be obtained by having the shape of the flow path described above. However, in such a flow meter, there is a strong demand for expanding the measurement range of the flow rate, and from this point, a flow rate that can measure a larger flow rate while satisfying the conditions for downsizing. Realization of the total was requested.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain a flowmeter capable of obtaining a stable measurement result and expanding a measurement range.

  In the flow meter according to the present invention, a space formed between an installation surface of a sensor for measuring a flow rate of a fluid and an opposing wall facing the installation surface is used as a sensor flow channel, and the sensor of the sensor flow channel is positioned. A flow path expansion portion having a size larger than the distance between the sensor installation surface and the opposing wall is provided at a position other than the flow path portion.

  In the flow meter according to the present invention, the flow path is formed so that the flow direction of the fluid from the upstream flow path located upstream of the sensor flow path to the sensor flow path is bent.

  The flow meter according to the present invention is such that the upstream flow path has a bent portion.

  In the flowmeter of the present invention, the flow rate is large because the flow channel expansion portion having a size larger than the distance between the sensor installation surface and the opposing wall is provided at a position other than the flow channel portion where the sensor is located in the sensor flow channel. Even in this case, the sensor can detect the flow rate stably, and the flow rate measurement range as a flow meter can be enlarged. In addition, since the flow path cross-sectional area necessary for the sensor flow path can be secured by the flow path extension portion, the distance between the sensor and the opposing wall can be further reduced. As a result, the fluid flowing through the sensor portion can be further reduced. Laminar flow can be achieved. Therefore, a stable flow measurement result can be obtained.

  In the flow meter of the present invention, since the flow path is formed so that the flow direction of the fluid from the upstream flow path to the sensor flow path is bent, a reproducible constant flow velocity distribution of the fluid flowing into the sensor flow path is formed. As a result, a more stable flow rate measurement result can be obtained.

  In the flowmeter of the present invention, the upstream flow path has a bent portion, so that a fluid flow collides with the wall portion of the bent portion to form a reproducible constant flow velocity distribution, and a stable flow measurement result. Can be obtained. This is because the flow having the flow velocity distribution at the time of flowing in from the input port changes when it hits the wall of the bent portion, the flow velocity distribution in the flow path is reorganized, and this is repeated, so that the flow before the input port is changed. This is because the flow velocity distribution formed in the flow path changes and a flow velocity distribution is formed by the bent portion.

Embodiment 1 FIG.
1 is a cross-sectional view of a flow meter according to Embodiment 1 of the present invention, and shows a cross-sectional view taken along line AA of FIG.
FIG. 2 is a cross-sectional view when viewed from the lateral direction with respect to the flow path of the flowmeter according to the first embodiment of the present invention.

  In these drawings, the flow meter includes a main body 1, a lid body 2, a circuit board 3, a sensor 4, a connector 5, and a metal pipe body 6. The main body 1 is formed of a resin, the circuit board 3 is bonded together, and one end portion of the lid body 2 is rotatably supported. The circuit board 3 is, for example, a ceramic substrate. A connector 5 and elements (not shown) having various functions are mounted on the upper surface of the circuit board 3, and the circuit board 3 is connected to the connector 5 on the lower surface of the circuit board 3. A sensor 4 is provided. This sensor 4 is, for example, a flow sensor in which a temperature measuring resistance element is arranged so as to sandwich a heater element.

  Here, for convenience of explanation, the upper surface and the lower surface mean directions in the illustrated state, but there is no particular distinction between the upward direction and the downward direction as the installation direction of the flowmeter of the present invention. .

  The metal pipe body 6 is embedded in the main body 1 and constitutes an input port 7 and an outlet port 8, and a hose (not shown) is connected to the inner peripheral surface of the metal pipe body 6. An internal thread is formed.

  In the main body 1. A flow path for detecting the flow rate by the sensor 4 is formed. This flow path includes a sensor flow path 101 that is a flow path portion where the sensor 4 is located, and an upstream flow path 102 and a downstream flow path 103 that are positioned upstream and downstream of the sensor flow path 101. . Further, the height dimension of the flow path where the sensor 4 is located in the sensor flow path 101 (the distance dimension between the installation surface of the sensor 4 and the opposing wall) a, and the distance dimension b between the upstream flow path 102 and the downstream flow path 103. Is a <b. Here, the height dimension “a” is, for example, 2 mm or less as a height dimension in which the flowing fluid is rectified by the viscosity of the fluid.

  The sensor flow path 101 is a linear flow path having a rectangular cross section defined by the main body 1 and the circuit board 3, and the sensor 4 is located at the center of the flow direction and the direction perpendicular to the flow (width direction). It is configured as follows. The sensor channel 101 has channel expansion portions 101a at both ends in the width direction. That is, the flow path expanding portion 101a having a dimension c larger than the distance dimension a between the sensor 4 and the opposing wall at a position other than the flow path portion (indicated by 200 in FIG. 1) where the sensor 4 is located in the sensor flow path 101. Is provided. The flow channel expanding portion 101a is formed by a space having a predetermined depth on both sides in the flow channel direction of the portion of the main body 1 where the sensor 4 is located, and is defined by the groove and the circuit board 3. is there. With such a configuration, in the sensor flow path 101 including the flow path expanding portion 101a, the cross section with respect to the flow direction is formed in a downward U-shape.

  Further, the dimension c of the flow path expanding portion 101a is set such that the lower end of the flow path expanded portion 101a is above the upper ends of the inlet port 7 and the outlet port 8 as shown in FIG. This is because it is necessary to form a flow path in which the fluid entering from the inlet port 7 hits the wall surface of the upstream flow path 102 rising vertically and is guided to the sensor flow path 101. The fluid flow will be described later.

  The upstream channel 102 is a channel that rises perpendicular to the sensor channel 101, and the downstream channel 103 is a channel that falls perpendicular to the sensor channel 101. The upstream flow path 102 communicates with the input port 7 and is formed to be perpendicular to the fluid flow direction of the inlet port 7 as described above, and the downstream flow path 103 is connected to the outlet port 8. And is perpendicular to the fluid flow direction of the outlet port.

  The flow meter configured in this way is installed in the flow path of the fluid to be measured, and fluid, for example, air flows from the inlet port 7 into the upstream flow path 102 and is guided to the sensor flow path 101. Then, it flows out through the downstream channel 103 and the outlet port 8. At that time, the flow direction of the fluid changes in the upstream channel 102. Next, a laminar flow is formed in the sensor flow path 101 with a shallow depth and a reduced cross-sectional area of the flow path, and the sensor 4 measures the flow state of the fluid, for example. The measured value is sent to a controller (not shown) via the connector 5, where the flow velocity value, that is, the flow rate is calculated.

  Here, since the flow path expanding portion 101a is provided in the sensor flow path 101 in which the sensor 4 is located, the sensor 4 can perform stable flow rate detection even at a large flow rate. The flow rate measurement range as a meter can be increased.

FIG. 3 is a diagram comparing the characteristics of the flowmeter of the present invention and a conventional flowmeter that does not have a flow path extension.
As is apparent from the characteristic 301 of the conventional flow meter and the characteristic 302 of the flow meter of the present invention in the figure, the conventional flow meter has the present invention even in a region where the sensor output with respect to the flow rate is saturated. The flow meter maintains the linearity of the sensor output with respect to the flow rate. Thereby, a sensor output with high accuracy can be obtained even at a large flow rate.

  In addition, since the upstream flow path 102 rises perpendicularly to the flow path of the inlet port 7 in this flow meter, the fluid flowing from the inlet port 7 hits the wall surface of the upstream flow path 102 and flows. The direction changes. Accordingly, when foreign matter is mixed in the fluid, the foreign matter is retained at the bottom of the upstream channel 102. Next, the fluid flows into the sensor flow channel 101. Since the flow channel of the sensor flow channel 101 is formed perpendicular to the upstream flow channel 102, the fluid flowing from the upstream flow channel 102 Is the wall surface of the sensor flow path 101, that is, the circuit board 3 and the flow direction changes. Accordingly, even if foreign matters are included in the fluid, the foreign matters are retained at the bottom of the upstream flow channel 102 and the meeting portion (corner) between the upstream flow channel 102 and the sensor flow channel 101. Similarly, foreign matter contained in the fluid is retained at the meeting portion (corner) between the sensor flow channel 101 and the downstream flow channel 103 and the bottom of the downstream flow channel 103.

  The flow having a flow velocity distribution formed upstream of the flow meter changes when it hits the wall surface of the upstream flow channel 102 and the wall surface of the sensor flow channel 101, and the flow velocity distribution in the flow channel is reorganized. As a result, a reproducible constant flow velocity distribution of the fluid flowing into the sensor flow path 101 is formed, and a stable flow measurement result can be obtained.

  As described above, according to the flow meter of the first embodiment, the dimension c larger than the distance dimension a between the installation surface of the sensor 4 and the opposing wall at a position other than the flow path portion where the sensor 4 is located in the sensor flow path 101. Is provided, the sensor 4 can stably detect the flow rate even when the flow rate is large, and the flow rate measurement range as a flow meter can be enlarged.

  In addition, since the flow channel expanding portion 101a is formed to have a predetermined size at both ends of the sensor flow channel 101, the sensor flow channel 101 is not enlarged in the width direction by the flow channel expanding portion 101a. As a flow meter, a flow meter having a large flow rate measurement range can be realized even when the width direction is particularly restricted.

  Furthermore, since the flowmeter according to the first embodiment does not use any rectifying mechanism or bypass flow path with a mesh plate, the adverse effect on the flow rate measurement due to the accumulation of dust can be greatly reduced. For example, in order to make it possible to measure a large flow rate, a bypass system in which a flow path in which a sensor is located and a bypass flow path is considered, but in such a system, the flow path in which the sensor is located due to accumulation of dust It is conceivable that the diversion ratio with respect to the bypass flow path changes greatly. On the other hand, since there is no bypass flow path in the flow meter of the first embodiment, such adverse effects can be avoided.

  Moreover, since the flow path cross-sectional area necessary for the sensor flow path 101 can be secured by the flow path expanding portion 101a, the distance dimension a between the installation surface of the sensor 4 and the opposing wall can be reduced. As a result, the fluid flowing through the sensor 4 can be made laminar, and a more stable flow measurement result can be obtained.

Embodiment 2. FIG.
4 is a cross-sectional view of a flow meter according to Embodiment 2 of the present invention, and shows a cross-sectional view taken along the line BB of FIG.
FIG. 5 is a cross-sectional view of the flowmeter according to the second embodiment of the present invention when viewed from the lateral direction.
In these drawings, the flow meter includes a main body 11, a lid body 12, a circuit board 13, a sensor 14, a lead wire 15, and packings 16 and 17. The main body 11 and the lid body 12 are each made of a resin such as PBT resin (polybutylene terephthalate), for example, and the main body 11 and the lid body 12 are integrally fixed by ultrasonic welding or the like. The circuit board 13 is a board provided with a circuit for detecting a flow rate by the sensor 14, and the sensor 14 is attached to the lower surface side of the circuit board 13 so as to constitute a part of a wall portion of the sensor flow path described later. ing. The circuit board 13 is configured to be integrally fixed to the main body 11.

  The sensor 14 is, for example, a flow sensor in which a resistance temperature element is disposed so as to sandwich the heater element, and is provided so as to slightly protrude into the sensor flow path. The lead wire 15 is a signal line for taking out the flow rate data detected by the sensor 14. The packing 16 is a packing for preventing fluid leakage between the circuit board 13 and the main body 11, and the packing 17 is a packing for preventing fluid leakage between the main body 11 and the manifold 18.

  A flow path for detecting a flow rate by the sensor 14 is formed in the main body 11. The flow path includes a sensor flow path 111 that is a flow path portion where the sensor 14 is located, an upstream side of the sensor flow path 111, and It is comprised from the upstream flow path 112 and the downstream flow path 113 which are located in the downstream. Further, the height dimension (the distance dimension between the sensor 14 and the opposing wall) a of the sensor flow path 111 perpendicular to the flow direction at the sensor 14 position is larger than the distance dimension b between the upstream flow path 112 and the downstream flow path 113. It is set small.

  The sensor flow path 111 is a linear flow path having a rectangular cross section defined by the main body 11 and the circuit board 13, and the sensor 14 is positioned at the center in the flow direction and the direction perpendicular to the flow. Yes. Further, in the sensor flow path 111, similarly to the flow path expansion section 101a of the first embodiment, the sensor flow path 111 is located at a position other than the flow path portion (indicated by 201 in FIG. 4) where the sensor 14 is located. A flow path expanding portion 111a having a dimension c larger than the distance dimension a between the installation surface of the sensor 14 and the opposing wall is provided. The upstream flow path 112 and the downstream flow path 113 are formed so that the flow path is bent at a substantially right angle with respect to the sensor flow path 111, and the upstream flow path 112 and the downstream flow path 113 are formed. In addition, bent portions 112 a and 113 a having a U-shaped cross section are provided between the manifold 18 and the manifold 18. Further, the upstream flow path 112 and the downstream flow path 113 are provided so as to be symmetric with respect to the position of the sensor 14.

  The height dimension a perpendicular to the flow direction at the sensor 14 position of the sensor flow path 111 is set to be smaller than the interval dimension b between the upstream flow path 112 and the downstream flow path 113. As described in the first embodiment, this is because the height dimension perpendicular to the fluid flow of the flow path portion where the sensor 14 is located is set to a height dimension rectified by the viscosity of the fluid. This is because the fluid flow in the vicinity can be rectified and laminarized. With such a shape, a stable measurement result by the sensor 14 can be obtained.

  Furthermore, as shown in FIG. 5, the dimension c of the flow path expanding portion 111a in the second embodiment is such that the lower end of the flow path expanded portion 111a is above the upper end surfaces 112b and 113b of the bent portions 112a and 113a. It is considered as a position. This is because the fluid that has flowed into the bent portion 112a (113a) has to hit the upper end surface 112b (113b) and change its direction, as will be described later.

  In the flow meter configured as described above, a fluid such as air flows from the inlet port 18 a of the manifold 18, which is guided to the sensor channel 111 via the upstream side passage 112, and further to the outlet port 18 b via the downstream side passage 113. Spilled from. At that time, the flow rate of the air flowing through the sensor flow path 111 is detected by the sensor 14, and the detected value is sent to a controller (not shown) via the lead wire 15, where the flow velocity value, that is, the flow rate is calculated.

  Here, in the present embodiment, in the upstream flow path 112, the flow path from the inlet port 18a is bent four times at substantially right angles. That is, the air flowing in from the inlet port 18a hits the wall portion of the bent portion 112a four times, and its flow direction changes. As described above, it has been experimentally confirmed that a reproducible constant flow velocity distribution is formed by changing the air flow direction a plurality of times (ie, hitting the wall portion a plurality of times). This is considered to be due to the following reason.

  The flow having a flow velocity distribution formed inside the flow path of the manifold 18 is changed by hitting the walls of the bent portions 112a and 113a, and the flow velocity distribution in the flow path is reorganized. And this is repeated in each flow path which comprises the bending parts 112a and 113a, the flow velocity distribution formed in the manifold 18 changes, and the flow velocity distribution by the bending parts 112a and 113a is formed.

  As a result, a reproducible constant flow velocity distribution of the fluid flowing into the sensor flow path 111 is formed, and a stable flow measurement result can be obtained.

  In addition, since the sensor flow path 111 is provided with the flow path extension 111a, a large flow rate can be flowed also in the flowmeter of the second embodiment. That is, the characteristics shown in FIG. 3 can be obtained, and the flow rate measurement range as a flow meter can be increased.

  As described above, according to the flowmeter of the second embodiment, the upstream flow path 112 has the bent portion 112a. In addition to the effects of the flowmeter of the first embodiment, the sensor flow path is further provided. A constant flow velocity distribution with reproducibility of the fluid flowing into 111 is formed, and a stable flow rate measurement result can be obtained.

Embodiment 3 FIG.
In the first and second embodiments, the sensor flow path is provided with a flow path expansion portion in contrast to the configuration in which the fluid flow direction of the upstream flow path or the downstream flow path and the fluid flow direction of the sensor flow path are bent. However, the present invention can be applied even when the fluid flow direction of the upstream flow path or the downstream flow path is the same as that of the sensor flow path, and this will be described below as a third embodiment.

6 is a cross-sectional view of the flow meter according to the embodiment of the present invention, and shows a cross-sectional view taken along the line CC of FIG.
FIG. 7 is a cross-sectional view of the flowmeter according to Embodiment 3 of the present invention when viewed from the lateral direction.
In these drawings, the flow meter includes a main body 21, a lid body 22, a circuit board 23, a sensor 24, and a lead wire 25. 27 is formed. Here, the basic configuration of the circuit board 23 and the lead wire 25 to which the main body 21, the lid 22 and the sensor 24 are attached is the same as that of the flowmeters of the first and second embodiments.

Further, as shown in FIG. 6, the configuration of the sensor flow path 121 and the flow path expanding portion 121a, which are flow path portions where the sensor 24 is located, is the same as in the first and second embodiments. That is, the sensor flow path 121 is a linear flow path having a rectangular cross section defined by the main body 21 and the circuit board 23 so that the sensor 24 is positioned at the center in the flow direction and the direction perpendicular to the flow. It has become. Further, the sensor flow path 121 has a dimension c larger than the distance dimension a between the installation position of the sensor 24 and the opposing wall at a position other than the flow path portion where the sensor 24 is located (indicated by 202 in FIG. 6). A channel expansion part 121a is provided. Further, the formation position of the flow path expanding part 121a in the flow direction is provided from the conical part 26a of the upstream flow path 26 to the conical part 27a of the downstream flow path 27.
The upstream flow path 26 and the downstream flow path 27 are flow paths formed in a cylindrical shape. Unlike the first and second embodiments, the fluid flow direction is the same as the fluid flow direction of the sensor flow path 121. It is comprised so that it may become.

  In the flow meter configured as described above, a fluid, for example, air flows from the upstream flow path 26, is guided to the sensor flow path 121, and further flows out from the downstream path 27. At that time, the flow rate of the air flowing through the sensor flow path 121 is detected by the sensor 24, and the detected value is sent to a controller (not shown) via the lead wire 25, where the flow velocity value, that is, the flow rate is calculated.

  In addition, since the sensor flow channel 121 is provided with the flow channel expansion portion 121a, a large flow rate can be flowed also in the flow meter of the third embodiment. That is, the characteristics shown in FIG. 3 can be obtained, and the flow rate measurement range as a flow meter can be increased.

  As described above, according to the flow meter of the third embodiment, the sensor channel 121 is larger than the distance dimension a between the installation surface of the sensor 24 and the opposing wall at a position other than the channel portion where the sensor 24 is located. Since the flow path expanding part 121a having the dimension c is provided, the sensor 24 can perform stable flow rate detection even when the flow rate is large, as in the first and second embodiments, and the flow rate measurement range as a flow meter. Can be increased.

  In the first to third embodiments, the flow path expanding portions 101a, 111a, 121a are formed on the main body 1, 11, 21 side, but may be formed so as to protrude on the circuit board 3, 13, 23 side. Good. That is, in the first to third embodiments, the flow path expanding portions 101a, 111a, and 121a are formed downward from the positions of the sensors 4, 14, and 24, but may be formed upward. Further, the shape of the flow path expanding portions 101a, 111a, and 121a is not limited to the rectangular cross section as in the first to third embodiments, and protrudes outside the width dimension of the sensor flow paths 101, 111, and 121. As long as it is in communication with the positions of the sensors 4, 14, 24 in the sensor flow paths 101, 111, 121, any shape may be used.

  In the first to third embodiments, the channel expansion portions 101a, 111a, and 121a are formed on both sides of the channel portions of the sensors 4, 14, and 24. However, only one side may be used.

Moreover, in Embodiment 1-3, it is applicable to various uses as a flowmeter, for example, it can apply not only to air as a fluid but to various things if it is gas.
Further, in the first to third embodiments, the case where the fluid flows from the upstream flow paths 102, 112, and 26 to the downstream flow paths 103, 113, and 27 has been described. 24, the upstream flow paths 102, 112, 26 and the downstream flow paths 103, 113, 27 are formed symmetrically, so that the upstream flow paths 102, 112 are connected to the downstream flow paths 103, 113, 27. , 26, the flow rate can be measured in the same manner.

It is sectional drawing of the flowmeter by Embodiment 1 of this invention. It is sectional drawing at the time of seeing the flowmeter by Embodiment 1 of this invention from a horizontal direction. It is explanatory drawing which compares and shows specification of the flowmeter by Embodiment 1 of this invention, and the conventional flowmeter. It is sectional drawing of the flowmeter by Embodiment 2 of this invention. It is sectional drawing at the time of seeing the flowmeter by Embodiment 2 of this invention from a horizontal direction. It is sectional drawing of the flowmeter by Embodiment 3 of this invention. It is sectional drawing at the time of seeing the flowmeter by Embodiment 3 of this invention from the horizontal direction.

Explanation of symbols

1, 11, 21 Main body 3, 13, 23 Circuit board 4, 14, 24 Sensor 26, 102, 112 Upstream flow path 27, 103, 113 Downstream flow path 101, 111, 121 Sensor flow path 101a, 111a, 121a Channel expansion part 112a, 113a Bent part

Claims (3)

  A space formed between the installation surface of the sensor for measuring the flow rate of the fluid and the opposing wall facing the installation surface is defined as a sensor flow path, and the space other than the flow path portion where the sensor is located in the sensor flow path. A flowmeter characterized in that a flow path expanding portion having a dimension larger than the distance between the sensor installation surface and the opposing wall is provided at a position.   2. The flowmeter according to claim 1, wherein the flow path is formed so that the flow direction of the fluid from the upstream flow path positioned upstream of the sensor flow path to the sensor flow path is bent. The flowmeter according to claim 2, wherein the upstream channel has a bent portion.

Images