JP7462304B2 - Point flow velocity detection device and cover for point flow velocity sensor - Google Patents

Description

The present invention relates to a point flow velocity detection device and a cover for a point flow velocity sensor.

Patent Document 1 describes a point flow velocity sensor that includes a rod-shaped detection arm that rotates in forward and reverse directions within a specified angle range around a rotation axis due to the water flow, and an acceleration sensor that rotates integrally with the detection arm and detects the angle of the detection arm.

JP 2019-158463 A

In the point flow velocity sensor described in Patent Document 1, a portion of the detection arm protrudes outward from an opening on the underside of the case. The water flow hitting the side of the case flows around to the underside of the case, causing the detection arm to rotate with a force greater than the force caused by the original point flow velocity, which can result in inaccurate detection of the point flow velocity. It is desirable to provide a point flow velocity detection device that can detect the point flow velocity more accurately.

The present invention aims to provide a point flow velocity detection device that can detect point flow velocity more accurately, and a cover for a point flow velocity sensor that enables the point flow velocity sensor to detect point flow velocity more accurately.

The present invention comprises a point flow velocity sensor that detects the point flow velocity of a water flow, and a point flow velocity sensor cover that covers the point flow velocity sensor. When the point flow velocity sensor is attached to a vertical installation surface, the point flow velocity sensor has a bottom surface parallel to the vertical direction, a top surface opposite the bottom surface, a lower surface facing the riverbed, an upper surface opposite the lower surface, an upstream side surface on which the forward flow of the water flow hits, and a reverse side surface on which the reverse flow of the water flow hits, and is provided with a case having an opening on the lower surface, and a detection arm, a portion of which protrudes from the opening to the outside of the case and which rotates in a forward or reverse direction within a predetermined angle range by the water flow around a rotation axis provided within the case, and the point flow velocity sensor is provided with a cover that covers the point flow velocity sensor. The flow velocity sensor cover provides a point flow velocity detection device that includes a top plate portion that covers the top surface, a first inclined portion that covers the upstream side surface and is inclined from the installation surface side toward the top plate portion as it approaches the point flow velocity sensor from a position away from the point flow velocity sensor, a second inclined portion that covers the reverse flow side surface and is inclined from the installation surface side toward the top plate portion as it approaches the point flow velocity sensor from a position away from the point flow velocity sensor, and a flange that is provided at the side end of the top plate portion and the first and second inclined portions on at least the lower surface side and protrudes in a direction perpendicular to the surfaces of the top plate portion and the first and second inclined portions.

The present invention is a cover for a point flow velocity sensor that covers a point flow velocity sensor, and the point flow velocity sensor has, when the point flow velocity sensor is attached to a vertical installation surface, a bottom surface parallel to the vertical direction, a top surface opposite the bottom surface, a lower surface facing the riverbed, an upper surface opposite the lower surface, an upstream side surface on which the forward flow of the water hits, and a reverse side surface on which the reverse flow of the water hits, and is equipped with a case having an opening on the bottom surface, and a detection arm, a portion of which protrudes from the opening to the outside of the case and which rotates in a forward or reverse direction within a predetermined angle range by the water flow around a rotation axis provided within the case, and the point flow velocity sensor cover is A cover for a point flow velocity sensor is provided that includes a top plate portion that covers the top surface, a first inclined portion that covers the upstream side surface and is inclined from the installation surface side toward the top plate portion as it approaches the point flow velocity sensor from a position away from the point flow velocity sensor, and is connected to the top plate portion, a second inclined portion that covers the reverse flow side surface and is inclined from the installation surface side toward the top plate portion as it approaches the point flow velocity sensor from a position away from the point flow velocity sensor, and a flange that is provided at the side end of the top plate portion and the first and second inclined portions on at least the lower surface side and protrudes in a direction perpendicular to the surfaces of the top plate portion and the first and second inclined portions.

The point flow velocity detection device of the present invention allows the point flow velocity to be detected more accurately. The point flow velocity sensor cover of the present invention allows the point flow velocity to be detected more accurately by the point flow velocity sensor.

1 is a plan view showing a state in which a lid of a point flow velocity sensor constituting a part of a point flow velocity detection device according to one embodiment is removed. FIG. 2 is a side view showing the point flow velocity sensor shown in FIG. 1 with the case cut away. 2 is an enlarged view, partially in cross section, showing the configuration around a rotation shaft in the point flow velocity sensor shown in FIG. 1 . 2 is a partial plan view showing the state of the cable in the point flow velocity sensor shown in FIG. 1 when the rotor and the acceleration sensor unit are rotated in the forward direction. FIG. 2 is a partial plan view showing the state of the cable in the point flow velocity sensor shown in FIG. 1 when the rotor and the acceleration sensor unit are rotated in the opposite directions. FIG. FIG. 2 is a plan view of the flow velocity detection device according to the embodiment, viewed from below. 1 is a perspective view showing a point flow velocity sensor cover constituting a part of a point flow velocity detection device of one embodiment, and a point flow velocity sensor cover of one embodiment. FIG. FIG. 2 is a plan view of a flow velocity detection device according to an embodiment, as viewed from the front. 11 is a block diagram showing an example of the configuration of a data transmission unit connected to a point flow velocity sensor. FIG.

The point flow velocity detection device and the cover for the point flow velocity sensor of one embodiment will be described below with reference to the attached drawings. First, an example of the configuration of a point flow velocity sensor constituting a part of the point flow velocity detection device of one embodiment will be described with reference to Figs. 1 to 4B. In Fig. 1, the point flow velocity sensor 10 is shown in a state where the lid 101b (see Fig. 2) has been removed from the case body 101a of the case 101. The case body 101a and the lid 101b are formed, for example, from a synthetic resin.

A base 103 made of a stainless steel plate is attached to the rotating shaft 121 attached to the bottom surface of the case body 101a so as to be rotatable in both forward and reverse directions. In FIG. 1, if counterclockwise rotation is the forward direction (+ direction), then clockwise rotation is the reverse direction (- direction). The detailed structure of the base 103, which is attached so as to be rotatable around the rotating shaft 121, will be described later.

An acceleration sensor unit 105 is fixed to the surface of the base 103. The acceleration sensor unit 105 is composed of a unit consisting of an acceleration sensor and a circuit board, and a mounting part 1051 to which the unit is attached. The mounting part 1051 of the acceleration sensor unit 105, the base 103, and the weight plates 107 to 109 shown in FIG. 2 are connected by a pair of screws 106. The weight plates 107 to 109 are made of stainless steel plates. As shown in FIG. 1 or 2, the base 103 and the weight plates 107 to 109 are connected by a pair of screws 110.

As shown in Figures 1 and 2, a protruding piece 107a is formed at the lower end of the weight plate 107, protruding perpendicular to the surface of the weight plate 107. A hole with a female thread is formed in the protruding piece 107a. A male thread is formed at the upper end of the detection arm 111. The detection arm 111 is fixed to the weight plate 107 by screwing the male thread at the upper end of the detection arm 111 into the female thread of the hole in the protruding piece 107a. As a result, the acceleration sensor unit 105 and the detection arm 111 are essentially integrated.

The weight plates 107-109 and the detection arm 111 are integrated with the base 103, which is rotatably attached to the rotation shaft 121, so that the base 103, the weight plates 107-109, and the detection arm 111 form a rotating body. The acceleration sensor unit 105 is integrated with the rotating body, so the acceleration sensor unit 105 rotates integrally with the rotating body around the rotation shaft 121.

A long, narrow rectangular opening 102 is formed on the underside of the case 101 (case body 101a). The underside of the case 101 is the surface that faces downward (towards the riverbed) when the point flow velocity sensor 10 is installed in water. A part of the detection arm 111 protrudes from the opening 102 to the outside of the case 101. The opening 102 may be a slit large enough for the detection arm 111 to pass through. The maximum angle that the detection arm 111 can rotate in the forward and reverse directions is determined by the position of the end of the opening 102.

As shown in FIG. 2 or FIG. 3, a rotating shaft 121, for example a flat head screw, is attached to the bottom surface (the right side surface in FIG. 2) of the case body 101a. A washer 122, a nut 123, a shaft fitting 124, a stainless steel pipe 125, a washer 128, and a nut 129 are passed through the rotating shaft 121. By tightening the nuts 123 and 129 to the rotating shaft 121, the shaft fitting 124 and the stainless steel pipe 125 are fixed to the rotating shaft 121 in a state where they are sandwiched between the nut 123 and the nut 129.

A cylindrical resin oil-free bushing 126 is passed through the stainless steel pipe 125. The diameter of the oil-free bushing 126 is slightly larger than the diameter of the stainless steel pipe 125. The oil-free bushing 126 is fitted into holes formed in the base 103 and the auxiliary plate 127. The auxiliary plate 127 is made of a stainless steel plate and is welded to the base 103. The auxiliary plate 127 fixed to the base 103 forms part of the rotating body. The oil-free bushing 126 is bonded to the base 103 and the auxiliary plate 127, and rotates integrally within a predetermined angle range around the stainless steel pipe 125.

The auxiliary plate 127 is provided because the thickness of the base 103 is significantly smaller than the axial length of the oil-free bushing 126. It is not essential to provide the auxiliary plate 127.

When the point flow velocity is 0 m/s, the detection arm 111 faces directly downward in the vertical direction, and the position of this detection arm 111 is the 0 point. When the detection arm 111 rotates to the right (counterclockwise) or left (clockwise) in FIG. 1 due to the water flow, the acceleration sensor unit 105 rotates. When the acceleration sensor unit 105 rotates, it can detect the forward or reverse angle of the detection arm 111. The detection value (voltage value) generated by the acceleration sensor unit 105 indicating the angle of the detection arm 111 (rotating body) is output to the outside of the point flow velocity sensor 10 via the cable 131.

Next, a specific configuration for easily returning the detection arm 111 to the 0 point when the point flow velocity becomes 0 m/s will be described. As shown in FIG. 1, the cable 131 is pulled out from the center of the acceleration sensor unit 105 in the width direction. The cable 131 has a U-shaped protrusion 132 that curves after heading in the right direction corresponding to the positive direction and returns to the center in the width direction at a position above the acceleration sensor unit 105. Furthermore, the cable 131 has a U-shaped protrusion 133 that is continuous with the protrusion 132, curves from the center in the width direction to the left direction corresponding to the reverse direction, and returns to the center in the width direction at a position further above the acceleration sensor unit 105.

A protrusion 133 may be formed on the cable 131 pulled out from the center of the width of the acceleration sensor unit 105, which turns leftward and then curves back to the center in the width direction, and a protrusion 132 may be formed next, which turns rightward and then curves back to the center in the width direction.

The cable 131 may have a first protrusion formed thereon, which is pulled out from the center in the width direction, moves toward a first direction corresponding to one of the forward and reverse directions, then curves, moves away from the acceleration sensor unit 105, and returns to the center in the width direction. In addition, the cable 131 may have a second protrusion formed thereon, which is continuous with the first protrusion, moves from the center in the width direction to a second direction corresponding to the other of the forward and reverse directions, then curves, moves further away from the acceleration sensor unit 105, and returns to the center in the width direction.

The first and second protrusions refer to the shape of the cable 131 when it is routed, protruding in the left and right directions from the center of the width of the acceleration sensor unit 105.

The cable 131 is continuous with the protrusion 133 and is routed in a straight line upward at the center of the width of the acceleration sensor unit 105. The cable 131 routed in a straight line is fixed to the shaft fitting 124 by a cable fixing plate 134. The cable fixing plate 134 is fixed to the shaft fitting 124 by a pair of screws 135. Furthermore, the cable 131 is pulled out to the outside from a cable pull-out pipe 136 provided in the case body 101a.

Figure 4A shows the state in which the rotating body and acceleration sensor unit 105 in the point flow velocity sensor 10 rotate in the forward direction. Figure 4B shows the state in which the rotating body and acceleration sensor unit 105 in the point flow velocity sensor 10 rotate in the reverse direction. As shown in Figure 4A, when the rotating body and acceleration sensor unit 105 rotate in the forward direction, the protrusion 132 expands and the protrusion 133 contracts. As shown in Figure 4B, when the rotating body and acceleration sensor unit 105 rotate in the reverse direction, the protrusion 132 contracts and the protrusion 133 expands.

Let us assume that the point flow velocity sensor 10 detects a predetermined point flow velocity and the rotor and acceleration sensor unit 105 rotate in the forward or reverse direction, and the point flow velocity becomes 0 m/s. Then, the protrusions 132 and 133, one of which has expanded and the other of which has contracted, will attempt to return to their original state, making it easier for the detection arm 111 to return to the 0 point. When the point flow velocity becomes 0 m/s, the detection arm 111 immediately returns to the 0 point.

In the point flow velocity sensor 10 shown in FIG. 1, the cable 131 is formed with a pair of protrusions that protrude in a first direction and a pair of protrusions that protrude in a second direction, but two or more pairs of protrusions may be formed. The number of protrusions that protrude in the first direction must be the same as the number of protrusions that protrude in the second direction.

In the point flow velocity sensor 10 shown in FIG. 1, the base 103 is attached to the rotating shaft 121 via an oil-free bushing 126 as a preferred configuration for making it easier to return the detection arm 111 to the zero point. In addition to providing the cable 131 with protrusions 132 and 133, it is also preferred to have the base 103 attached to the rotating shaft 121 via an oil-free bushing 126.

In the point flow velocity sensor 10 shown in FIG. 1, the rotating body and acceleration sensor unit 105 are configured as follows, as a more preferable configuration for making it easier to return the detection arm 111 to the zero point. The acceleration sensor unit 105 is attached to the first surface (front surface) of the base 103. Weight plates 107 to 109 are attached as part of the rotating body to the second surface (back surface) of the base 103 opposite the first surface. However, the protruding piece 107a of the weight plate 107 is substantially located on the first surface side. The detection arm 111 is located on the first surface side.

The moment determined by the weight of each of the acceleration sensor unit 105, protruding piece 107a, and detection arm 111 located on the first surface side of the base 103 and their position relative to the base 103 is defined as the first moment. The moment determined by the weight of each of the weight plates 107 to 109 (excluding protruding piece 107a) located on the second surface side of the base 103 and their position relative to the base 103 is defined as the second moment. In this embodiment, the first moment and the second moment are set to be 87% equal.

In other words, the weight of each part (acceleration sensor unit 105, weight plates 107-109, detection arm 111) and the position of each part relative to base 103 are set so that the rotating body and acceleration sensor unit 105 do not tilt toward the bottom surface of case body 101a or toward lid 101b, and the detection arm 111 faces directly downward in the vertical direction when the point flow velocity is 0 m/s.

In the point flow velocity sensor 10 shown in FIG. 1, three weight plates 107 to 109 are provided, but the number of weight plates is not limited to three in order to equalize the weight of the first surface side and the weight of the second surface side of the base 103. The size and number of weight plates are design matters.

Next, a point flow velocity detection device and a cover for a point flow velocity sensor according to an embodiment, which is configured with the point flow velocity sensor 10 described above, will be described with reference to Figures 5 to 7. As shown in Figure 5, an L-angle 30 is fixed to a specific structure 300 in a river. A metal fitting 12 with a U-shaped cross section is attached to the L-angle 30. The metal fitting 12 has a top plate portion 1201 and legs 1202a and 1202b that are at an angle of 90 degrees to the top plate portion 1201. The metal fitting 12 is formed by bending a single stainless steel plate.

Figure 5 shows an example of installation on the left bank. When installing on the right bank, the L-angle 30 is fixed to the structure 300 with the left and right reversed, and the metal fitting 12 is attached to the L-angle 30.

A connecting plate 13a is attached to one end of the top plate portion 1201 of the metal fitting 12 by a flat head screw 14a, and a connecting plate 13b is attached to the other end of the top plate portion 1201 by a flat head screw 14b. The connecting plates 13a and 13b have a first portion 1301 parallel to the top plate portion 1201, and a second portion 1302 that faces the structure 300 at an angle of more than 90 degrees to the first portion 1301. The ends of the first portion 1301 are fixed to the top plate portion 1201 by flat head screws 14a and 14b. The connecting plates 13a and 13b are each formed by bending a single stainless steel plate.

The point flow velocity sensor 10 described above is fixed to the top plate portion 1201 by screws or the like (not shown). The point flow velocity sensor cover 16 covers the metal fittings 12 and the point flow velocity sensor 10. Figure 6 is a perspective view showing the point flow velocity sensor cover 16. As shown in Figures 5 and 6, the point flow velocity sensor cover 16 has a top plate portion 161 and inclined portions 162a and 162b that are at an angle of more than 90 degrees with respect to the top plate portion 161 and point toward the structure 300.

Flanges 163a and 163b are provided on both side ends of the top plate portion 161 and the inclined portions 162a and 162b. The flanges 163a and 163b protrude in a direction perpendicular to the surfaces of the top plate portion 161 and the inclined portions 162a and 162b. The height of the flanges 163a and 163b is approximately 10 mm at the top plate portion 161. The height of the flanges 163a and 163b decreases in sequence toward the ends of the inclined portions 162a and 162b opposite the top plate portion 161.

The top plate portion 161 and the inclined portions 162a and 162b are formed by bending a single stainless steel plate. The flanges 163a and 163b are welded to both side ends of the top plate portion 161 and the inclined portions 162a and 162b, and are integrated with the top plate portion 161 and the inclined portions 162a and 162b.

As shown in FIG. 5, the second portions 1302 of the connecting plates 13a and 13b have the same inclination angle as the inclined portions 162a and 162b. The second portions 1302 are fixed to the inclined portions 162a and 162b by countersunk screws 15a and 15b. The connecting plates 13a and 13b connect the metal fitting 12 and the point flow velocity sensor cover 16.

In the configuration example shown in FIG. 5, the point flow velocity sensor 10, the metal fittings 12, the connecting plates 13a and 13b, and the point flow velocity sensor cover 16 constitute the point flow velocity detection device 100. The point flow velocity detection device 100 may be constituted by at least the point flow velocity sensor 10 and the point flow velocity sensor cover 16.

Figure 7 shows the point flow velocity detection device 100 fixed to the L-angle 30 as seen from the front. The point flow velocity sensor 10 is attached to a vertical installation surface. The surface of the structure 300 or the top plate 1201 of the metal fitting 12 is the installation surface. In this state, the case 101 of the point flow velocity sensor 10 has a bottom surface parallel to the vertical direction, a top surface opposite the bottom surface, a lower surface facing the riverbed, a top surface opposite the lower surface, an upstream side surface on the side where the forward flow of water hits, and a reverse side surface on the side where the reverse flow of water hits. The top surface of the lid 101b is the top surface.

The top plate portion 161 of the point flow velocity sensor cover 16 covers the top surface of the case 101. The inclined portion 162a (first inclined portion) covers the upstream side of the case 101, and as it approaches the point flow velocity sensor 10 from a position away from the point flow velocity sensor 10, it is inclined from the installation surface side toward the top plate portion 161 side and connected to the top plate portion 161. The inclined portion 162b (second inclined portion) covers the reverse flow side of the case 101, and as it approaches the point flow velocity sensor 10 from a position away from the point flow velocity sensor 10, it is inclined from the installation surface side toward the top plate portion 161 side and connected to the top plate portion 161.

The forward flow Wc1 flowing below the point flow velocity sensor cover 16 rotates the detection arm 111. Suppose that the forward flow Wc2 that hits the inclined portion 162a flows downward. The flange 163a prevents the downward flow of the forward flow Wc2 from flowing below the case 101, thereby reducing the force that the forward flow Wc2 exerts on the detection arm 111, thereby reducing the occurrence of turbulence and making it easier to detect only the forward flow Wc1. Thus, the point flow velocity detection device 100 can detect the point flow velocity more accurately. The point flow velocity sensor cover 16 allows the point flow velocity sensor 10 to detect the point flow velocity more accurately.

The point flow velocity sensor cover 16 may include a flange 163a provided at least on the side end of the bottom surface of the case 101 at the top plate portion 161 and the inclined portions 162a and 162b. As shown in FIG. 7, it is preferable that the point flow velocity sensor 10 and the point flow velocity sensor cover 16 are positioned relative to each other so that the flange 163a is at the same vertical position as the bottom surface of the case 101. It is preferable that the flange 163b is located above the top surface of the case 101.

Using Figure 8, we will explain how the point flow velocity detected by the point flow velocity detection device 100 (point flow velocity sensor 10) is used. As shown in Figure 8, a data transmission unit 20 is connected to the point flow velocity sensor 10. The data transmission unit 20 is attached above the support on which the point flow velocity sensor 10 is attached, separated from the point flow velocity sensor 10 by a predetermined distance.

The data transmission unit 20 includes a level converter 21 that converts the level of the digital detection value supplied from the point flow velocity sensor 10 via the cable 131, a central processing unit 22 (hereinafter, CPU 22) that converts the detection value into point flow velocity data, and a radio 23 that wirelessly transmits the point flow velocity data. The data transmission unit 20 also includes a power supply unit 24 that supplies power to each unit in the data transmission unit 20 and the point flow velocity sensor 10. The power supply unit 24 may be a solar panel and a rechargeable battery, or may be a pre-charged rechargeable battery or dry cell.

In the configuration shown in FIG. 8, the cable 131 consists of a cable that supplies the point flow velocity detected by the point flow velocity sensor 10 to the data transmission unit 20, and a cable that supplies power from the power supply unit 24 to the point flow velocity sensor 10.

The wireless device 23 transmits the point flow velocity data based on the angle of the rotation direction of the base 103 detected by the point flow velocity sensor 10 to a relay station or a monitoring office that monitors the river.

The present invention is not limited to the embodiment described above, and various modifications are possible without departing from the gist of the present invention. The point flow velocity sensor 10 shown in Figures 1 to 4B shows a preferred configuration example of a point flow velocity sensor configured to easily return the detection arm to the 0 point when the point flow velocity becomes 0 m/s. The specific configuration of the point flow velocity sensor is not limited to the point flow velocity sensor 10 shown in Figures 1 to 4B. However, it is preferable that the point flow velocity sensor be the point flow velocity sensor 10 shown in Figures 1 to 4B.

10 flow velocity sensor 12 metal fittings 13a, 13b connecting plate 16 flow velocity sensor cover 30 L angle 101 case 101a case body 101b lid 102 opening 103 base 105 acceleration sensor unit 107-109 weight plate 111 detection arm 121 rotating shaft 125 stainless steel pipe 126 oil-free bush 131 cable 132, 133 protruding portion 161 top plate portion 162a, 162b inclined portion 163a, 163b flange 300 structure

Claims (3)

A point flow velocity sensor for detecting a point flow velocity of the water flow;
A point flow rate sensor cover for covering the point flow rate sensor;
Equipped with
The point flow velocity sensor is
a case having a bottom surface parallel to the vertical direction, a top surface opposite the bottom surface, a lower surface facing the riverbed, an upper surface opposite the bottom surface, an upstream side surface on which the forward flow of the water current hits, and a reverse flow side surface on which the reverse flow of the water current hits, with an opening formed on the bottom surface when the point flow velocity sensor is attached to a vertical installation surface;
a detection arm having a portion protruding from the opening to the outside of the case and adapted to rotate in a forward or reverse direction within a predetermined angle range around a rotation axis provided within the case by the water flow;
Equipped with
The point flow rate sensor cover is
A top plate portion covering the top surface;
a first inclined portion that covers the upstream side surface and is inclined from the installation surface side toward the top plate portion as the point flow velocity sensor approaches the point flow velocity sensor from a position away from the point flow velocity sensor, and is connected to the top plate portion;
A second inclined portion covers the reverse flow side surface, and is inclined from the installation surface side toward the top plate portion as it approaches the point flow velocity sensor from a position away from the point flow velocity sensor, and is connected to the top plate portion;
a flange provided at least at a side end portion on the lower surface side of the top plate portion and the first and second inclined portions, the flange protruding in a direction perpendicular to the surfaces of the top plate portion and the first and second inclined portions;
A point flow velocity detection device. The point flow velocity detection device according to claim 1, wherein the point flow velocity sensor and the point flow velocity sensor cover are positioned relative to each other so that the flange is at the same vertical position as the bottom surface of the case. A cover for a water flow velocity sensor that covers a water flow velocity sensor that detects the water flow velocity.
The point flow velocity sensor is
a case having a bottom surface parallel to the vertical direction, a top surface opposite the bottom surface, a lower surface facing the riverbed, an upper surface opposite the bottom surface, an upstream side surface on which the forward flow of the water current hits, and a reverse flow side surface on which the reverse flow of the water current hits, with an opening formed on the bottom surface when the point flow velocity sensor is attached to a vertical installation surface;
a detection arm having a portion protruding from the opening to the outside of the case and adapted to rotate in a forward or reverse direction within a predetermined angle range around a rotation axis provided within the case by the water flow;
Equipped with
The point flow rate sensor cover is
A top plate portion covering the top surface;
a first inclined portion that covers the upstream side surface and is inclined from the installation surface side toward the top plate portion as the point flow velocity sensor approaches the point flow velocity sensor from a position away from the point flow velocity sensor, and is connected to the top plate portion;
A second inclined portion covers the reverse flow side surface, and is inclined from the installation surface side toward the top plate portion as it approaches the point flow velocity sensor from a position away from the point flow velocity sensor, and is connected to the top plate portion;
a flange provided at least at a side end portion on the lower surface side of the top plate portion and the first and second inclined portions, the flange protruding in a direction perpendicular to the surfaces of the top plate portion and the first and second inclined portions;
Cover for flow velocity sensor.

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