JP2012173102A - Self-excitation type flow velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow velocity sensor capable of directly detecting the flow velocity of a fluid in conformity with the flow of the fluid.SOLUTION: The flow velocity sensor includes a vortex generation part 4 which periodically generates a vortex in the fluid flowing in a flow passage 2, and a self-excitation type power generation sheet 6 which vibrates by periodic behavior of vortexes to generate electric power. Vibration period detection means 10 of finding the vibration period of the power generation sheet 6 based upon the frequency of the electric power generated by the power generation sheet 6 is provided while electrically connected to the power generation sheet 6. Further, there is provided flow velocity derivation means 11 of deriving the flow velocity of the fluid based upon the vibration period of the power generation sheet 6 detected by the vibration period detection means 10.

Description

  The present invention relates to a flow rate sensor that measures a flow rate of a fluid flowing through a flow path.

  Conventionally, there are a wide variety of such flow rate sensors. As an example, there is a flow rate sensor that detects the flow rate of fluid based on the periodic behavior of Karman vortex, and is generally known as a Karman flow meter that detects the flow rate of fluid based on the detected flow rate ( For example, see Patent Document 1).

JP-A-3-20618

  However, the flow velocity sensor applied to the Karman flowmeter adopts a configuration in which the pressure at two locations where a pressure difference is caused by the behavior of the Karman vortex is guided to the pressure sensor via a pressure guiding path or the like, and is detected. It is not a configuration in which the flow velocity is directly detected in a state in accordance with the flow of the fluid, that is, in a state along the flow of the vortex in the fluid.

  The present invention pays attention to such points, and an object of the present invention is to provide a flow rate sensor capable of directly detecting the flow rate of the fluid in a state in accordance with the flow of the fluid.

  In order to achieve the above object, the flow velocity sensor characteristic configuration for measuring the flow velocity of the fluid flowing in the flow channel according to the present invention periodically generates vortices in the fluid flowing in the flow channel. A vibration that includes a vortex generator and a self-exciting power generation sheet that generates electric power by vibrating due to the periodic behavior of the vortex, and determines the vibration period of the power generation sheet based on the frequency of the power generated by the power generation sheet A period detecting means is provided electrically connected to the power generation sheet, and a flow velocity deriving means for deriving the flow velocity of the fluid based on the vibration period of the power generation sheet detected by the vibration period detecting means is provided. It is in.

According to the above characteristic configuration, a self-excited power generation sheet is used to detect the flow velocity of the fluid, and the power generation sheet vibrates along the vortex due to the periodic behavior of the vortex generated by the vortex generator. Therefore, the flow velocity of the fluid is detected based on the frequency of the electric power, so that the flow velocity of the fluid can be directly detected in a state corresponding to the flow of the fluid.
And, based on the frequency of the electric power generated by the power generation sheet, the vibration period detecting means obtains the vibration period of the power generation sheet, and based on the vibration period of the power generation sheet, the flow velocity deriving means derives the flow velocity of the fluid. There is no need to supply electric power to the power generation sheet, and the flow velocity of the fluid flowing through the flow path can be directly detected in a state in accordance with the flow of the fluid.

  In the flow sensor having the above characteristic configuration, a vortex generating groove perpendicular to the fluid flow direction is provided below the flow path, and the fluid flow direction upstream side of the upper edge of the vortex generation groove It is preferable that the edge located at is configured as a vortex generating edge that functions as the vortex generating portion, and the power generation sheet is attached to the vortex generating edge.

According to the above characteristic configuration, by providing the vortex generating groove below the flow path through which the fluid flows, the upper edge on the upstream side in the flow direction of the vortex generating groove functions as a vortex generating portion. The flow velocity of the fluid can be detected without greatly disturbing the flow of the fluid as in the case where the vortex generator is provided inside the flow path through which the fluid flows.
Since the power generation sheet is attached to the vortex generation edge that functions as the vortex generation portion, the vortex generation groove can be disposed below the flow path with the power generation sheet previously attached to the vortex generation edge. Thus, the flow velocity detection operation can be facilitated.

  In the flow rate sensor having the above-described characteristic configuration, the power generation sheet is attached to an intermediate position in the longitudinal direction of the vortex generation edge, and fluid can flow into the vortex generation groove on both sides of the power generation sheet. It is preferable that a portion is provided.

  According to the above characteristic configuration, the fluid flowing in the flow path flows into the vortex generating groove from both sides of the power generating sheet attached to the vortex generating edge, so that a vortex is generated near the power generating sheet. The vibration of the power generation sheet becomes remarkable, and the flow rate of the fluid can be detected more reliably.

Schematic configuration perspective view showing a first embodiment of a self-excitation flow rate sensor Longitudinal side view of the first embodiment of the self-excitation flow rate sensor (indicated by arrows II-II in FIG. 1) Longitudinal side view of the first embodiment of the self-excitation flow rate sensor Longitudinal side view of a second embodiment of a self-exciting flow rate sensor

[First Embodiment]
A first embodiment of a self-excitation flow rate sensor according to the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 3, the self-excitation flow rate sensor according to the first embodiment passes through the flow path 2 in a flow path 2 formed by a pipe 1 having a rectangular or circular cross section. A vortex generating groove 3 that intersects perpendicularly to the flow direction F of a fluid such as a flowing gas (for example, city gas) or a liquid is provided below the flow path 1.
In the vortex generating groove 3, the edge 4 located on the upstream side in the fluid flow direction F among the upper edges 4 and 5 is configured as a vortex generating edge 4 that functions as a vortex generating portion. The generation edge 4 is configured to periodically generate vortices in the fluid flowing through the flow path 2.

At the middle position in the longitudinal direction of the edge 4 for vortex generation, more specifically, at the center in the longitudinal direction of the edge 4 for vortex generation, excellent flexibility and water resistance and impact resistance are achieved by thinning. One side of the provided self-excited rectangular power generation sheet 6 is attached by, for example, adhesion, and a fluid inflow portion 7 through which fluid can flow into the vortex generating groove 3 is provided on both sides of the power generation sheet 6. ing.
The power generation sheet 6 is made of a ferroelectric polymer typified by polyfucavinylidene, more specifically, for example, a piezoelectric film (trade name, manufactured by Tokyo Sensor Co., Ltd.), and is self-excited by vibration. Thus, it has a characteristic of generating high voltage power.
Two lead wires 8 are connected to the power generation sheet 6, and terminals 8 a of the lead wires 8 are provided in the vortex generating groove 3 so as to protrude to the outside, and the power generation sheet 6, the lead wires 8, And the terminal 8a is assembled | attached to the groove | channel 3 for vortex generation, and is comprised by one unit.

A vibration period detecting means 10 is connected to the terminal 8 a of the lead wire 8 connected to the power generation sheet 6 via two cables 9. In other words, the vibration period detection means 10 is provided in electrical connection with the power generation sheet 6 via the two lead wires 8 and the cable 9, and the vibration period detection means 10 provides the power generated by the power generation sheet 6. A vibration cycle of the power generation sheet 6 is obtained based on the frequency, and a flow velocity deriving unit 11 is connected to the vibration cycle detecting unit 10.
The flow velocity deriving unit 11 stores relational data between the vibration cycle of the power generation sheet 6 and the flow velocity of the fluid that are measured in advance, and based on the vibration cycle of the power generation sheet 6 transmitted from the vibration cycle detection unit 10. It is configured to derive the flow velocity.

According to the self-excitation flow velocity sensor having such a configuration, the vortex generating groove 3 is arranged downstream of the vortex generating edge 4, that is, as shown in FIG. Inside, a vortex is periodically generated on the lower lateral side of the power generation sheet 6, and the vortex is peeled off from the vortex generating edge 4 and flows upward from the vortex generating groove 3 as shown in FIG. . Due to the periodic behavior of the vortices, the power generation sheet 6 vibrates upward from the state shown in FIG. 2 in accordance with the flow of the fluid to the state shown in FIG. 3, and then again shown in FIG. It becomes a state, and it generates power by repeatedly vibrating up and down.
Based on the frequency of the electric power generated by the power generation sheet 6, the vibration cycle detection unit 10 detects the vibration cycle of the power generation sheet 6 and transmits the detection result to the flow velocity deriving unit 11.
The flow velocity deriving unit 11 derives the flow velocity of the fluid corresponding to the vibration cycle based on the transmitted vibration cycle of the power generation sheet 6 and displays the derived flow velocity on the display device, for example. Of course, the flow rate of the fluid flowing in the flow path 2 can also be obtained from the flow velocity.

[Second Embodiment]
The second embodiment of the self-excitation flow velocity sensor according to the present invention will be described, but in order to avoid duplication, the configuration described in the first embodiment and the configuration having the same action are described by attaching the same reference numerals. A description will be mainly given of a configuration different from that of the first embodiment.
The self-exciting flow velocity sensor according to the second embodiment is as shown in FIG. 4, and is different from the first embodiment in that one side of the self-exciting power generation sheet 6 formed in a rectangular shape is for vortex generation. In addition to being attached to the central portion of the edge 4 in the longitudinal direction, the other side of the power generation sheet 6 (side facing the one side) is also attached to the downstream edge 5 by adhesion, for example. The power generation sheet 6 is configured to vibrate.
Also in this embodiment, the power generation sheet 6 largely vibrates up and down due to the behavior of vortices generated periodically, and finally the fluid flow velocity can be detected.

[Another embodiment]
(1) In the embodiments described so far, the example in which the power generation sheet 6 is attached to the middle position in the longitudinal direction of the vortex generating edge 4 has been shown. It can also be attached.
(2) Moreover, although the example which comprised the vortex generating part by the upper edge 4 of the upstream of the vortex generating groove 3 was shown, for example, the member which has an edge protrudes in the flow path 2, and the protruding edge A vortex generator can also be configured, and various modifications can be made to the vortex generator.

2 Flow path 3 Vortex generating groove 4 Vortex generator (vortex generating edge)
6 Self-exciting power generation sheet 7 Fluid inflow section 10 Vibration period detecting means 11 Flow velocity deriving means F Flow direction of fluid

Claims (3)

A flow rate sensor for measuring a flow rate of a fluid flowing through a flow path,
A vortex generator that periodically generates vortices in the fluid flowing in the flow path, and a self-excited power generation sheet that generates electric power by vibrating due to the periodic behavior of the vortex, the power generation sheet The vibration period detecting means for obtaining the vibration period of the power generation sheet based on the frequency of the electric power generated by the power generation sheet is electrically connected to the power generation sheet, and is detected by the vibration period detection means. Self-excited flow rate sensor provided with flow rate deriving means for deriving the flow rate of fluid based on the above.   A vortex generating groove perpendicular to the fluid flow direction is provided below the flow path, and an edge located upstream of the fluid flow direction in the upper edge of the vortex generation groove is the vortex generating portion. The self-exciting flow velocity sensor according to claim 1, wherein the self-excitation flow velocity sensor is configured as a vortex generating edge that functions as the vortex generating edge.   The power generation sheet is attached to an intermediate position in the longitudinal direction of the vortex generation edge, and a fluid inflow portion through which fluid can flow into the vortex generation groove is provided on both sides of the power generation sheet. The described self-exciting flow rate sensor.

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