JPS62207961A - Flow velocity measuring instrument - Google Patents

Abstract

PURPOSE:To improve the rain drop resistance by generating a pressure signal in accordance with the pressure of the inside of a cylindrical member provided in parallel to the flow of a fluid, and deriving the flow velocity from this pressure signal. CONSTITUTION:A wind flows in parallel roughly along passage plates 17, 18, in a passage 20 formed by the plates 17, 18, and flows at the highest speed in the vicinity of the opening end 22a of a wind velocity detecting cylinder 22, therefore, negative pressure is generated in the cylinder 22. This negative pressure has a characteristic by which it becomes high as the wind velocity rises. Therefore, the pressure generated in the cylinder 22 is led to a semiconductor pressure sensor 24 by a pressure port 22b and a pressure leading-out tube 23, and measured, and from this pressure signal, the wind velocity is measured. Also, in case of a windy state, the negative pressure is generated in the cylinder 22, and the opening end 22a opens downward, therefore, it does not occur that a rain drop, dust, etc., invade the pressure port 22b and the pressure leading-out tube 23.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a flow rate measuring device for measuring the flow rate of a fluid.
For example, it is effective when used as a wind speed sensor that is attached to a vehicle antenna, roof, etc. to measure wind speed.

[Conventional technology]

As a conventional flow velocity measuring device, for example,
As shown in Publication No. 233, etc., this chamber is equipped with four sensing chambers divided in orthogonal directions along the longitudinal axis, and a probe equipped with a pressure sensing boat that communicates each chamber with the outside. There are devices that measure wind speed in a specific direction based on the air pressure difference.

[Problem that the invention seeks to solve]

However, the conventional method has the problem that although it is possible to individually measure the wind speed in one specific direction determined by the arrangement of the sensing boat, it is difficult to measure the flow speed in all directions. Additionally, due to the relationship between the hole position of the pressure-sensing boat and the direction of the flow velocity, we have solved the problem that raindrops, dust, etc. may enter or adhere to the boat in response to wind in a specific direction, affecting the flow velocity measurement value. had.

An object of the present invention is to provide a flow rate measuring device that solves the above problems. That is, an object of the present invention is to provide a flow velocity measurement device that is compact and capable of measuring flow velocity in all directions when installed outside of a vehicle such as a vehicle, which has excellent weather resistance, particularly raindrop resistance. .

[Means for solving problems]

In order to solve the above problems, the present invention has a cylindrical shape with an open end at one end, and the outer periphery of the open end faces downward and is arranged parallel to the flow of fluid. a pressure detection means for generating a pressure signal according to the pressure inside the cylindrical member; and a flow velocity calculation means for receiving the pressure signal from the pressure detection means and calculating a flow velocity from the pressure signal. Features.

[Effect]

In the present invention, with the above configuration, when fluid flows around the open end of the cylindrical member, negative pressure is generated from the open end of the cylindrical member to the inside thereof. Since this negative pressure changes depending on the flow rate, this negative pressure can be detected by the pressure detection means and the flow rate can be calculated from this pressure signal.

〔Effect of the invention〕

In the present invention, since the cylindrical member having an open end at one end is disposed such that the open end faces downward, raindrops and the like flying with the fluid are less likely to enter the cylindrical member. Furthermore, when fluid is flowing, the interior of the cylindrical member is under negative pressure, so even if raindrops or the like adhere to the inside of the pressure conduit, these will be absorbed by the negative pressure generated inside the cylindrical member. It has the effect of being pulled out toward the open end side of the cylindrical member by the pressure. Furthermore, by providing a cylindrical member, the present invention generates negative pressure within the cylindrical member according to the flow velocity for detection, and therefore has the excellent effect of being simple in structure and being able to be miniaturized. .

〔Example〕

A first embodiment of the present invention will be described below using a wind speed measuring device attached to the tip of an antenna rod.

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG.
FIG. 3 is a line A-A in FIG. 1.

FIG. 4 is a cross-sectional view taken along line B-B, and FIG. 4 is a partial cross-sectional view of the wind speed sensor.

Reference numeral 10 denotes an antenna rod, the lower end 10a of which is supported by a support case 1) fixed to a part of the vehicle body, and the rod 10 is screwed to a pole 12 so that it can be thrown sideways in the longitudinal direction of the vehicle body in an emergency. There is. Upper end 10 of rod 10
A case 13 for detecting and measuring wind speed and direction is fixed to b.

The entire outer shape of the case 13 is cylindrical so that the wind speed value is not affected by wind directions in all directions. This case 13 includes a lower case part 13a fixed to the rod 10,
3 of the upper intermediate case part 13b and the upper case part 13c.
It has a tiered structure. Each case part 13a, 13b, 13c is
Channel plates 15 and 16, 17 and 18 are supported in parallel by a net-like member centered around a plurality of thin support columns 14 provided along the outer periphery of the channel plates 15 to 18.
Two channels 20 and 21 are formed by this.

As shown in FIG. 2, a wind speed detection cylinder 22 is vertically attached to the upper flow path plate 18 of the flow path 20 at the center thereof. The cylinder 22 has a diameter of about 3 mm-10*m, is cut along a plane perpendicular to its central axis, and has a diameter of about 3 mm-10*m.
．． The hole end 22a has an end face parallel to the hole 18. The open end 22a opens downward with respect to the channel plate 18. As a result, the wind is guided so as to be parallel to the end surface of the open end 22a of the cylinder 22, and at the same time, raindrops and the like do not enter the cylinder 22. Further, a gap 37 is provided in the upper part of the cylinder 22, and a pressure boat 22b is formed on the side of this gap 37 to lead out the pressure inside the cylinder 22 to the outside, and a pressure derivation tube 23 is provided in the pressure boat 22b. ing. The purpose of this gap 37 is to prevent raindrops, dust, dirt, etc. from blocking the pressure boat 22b.
Pressure capo to alleviate rapid pressure fluctuations and create stable negative pressure)2
2b. The pressure inside the cylinder 22 is transferred to the support case 1 through a pressure outlet tube 23.
) is guided to a semiconductor pressure detector 24 provided within the interior.

The tube 23 includes an upper case portion 13c and an intermediate case portion 13b.
, a pipe 25 passing through the upper case portion 13a, and passing through the antenna wand 10 to the support case 1). In order to reduce the influence of the pipe 25 on the wind speed detection cylinder 22, the pipe 25 is installed on the downstream side with respect to the main wind direction to be detected, for example, in the case of a vehicle, it is installed at a position on the rear side in the direction of travel of the vehicle. There is.

Furthermore, wind direction measuring cylinders 30, 31, and 32 are attached to the upper channel plate 16 of the channel 21, as shown in FIG. Each cylinder 30, 31.32 has a pressure detection hole 30a, 31a opening toward the downstream side.

32a is provided, and the pressure in the holes 30a, 31a, 32a is detected by a semiconductor pressure detector 33.
0 cylinders 30 and 31 led by 34, or cylinder 30
and 32, there is a phenomenon in which a negative pressure depending on the wind direction is generated on the downstream side of the cylinder 30 at a constant wind speed, and the pressure detector 33 can detect the wind direction by this negative pressure. In addition, the pressure detector 34 detects the difference in negative pressure generated on the downstream side of the cylinders 31 and 32 provided at symmetrical positions, and determines whether the wind is coming from the left or right direction. .

Next, the operation of measuring wind speed based on the above configuration will be explained.

FIG. 4 shows a partially enlarged cross-sectional view of FIG.
．． 18 and flows fastest near the open end 22 of the cylinder 22, a negative pressure is generated within the wind speed detection cylinder 22. This negative pressure (PV) has a characteristic of increasing as the wind speed (U) increases, as shown in FIG. Therefore, the pressure generated inside the cylinder 22 is reduced to the pressure boat 22.
b.

The pressure is guided to the semiconductor pressure sensor 24 through the pressure derivation tube 23 for measurement, and the wind speed can be measured from this pressure signal.

In addition, in a windy state, negative pressure is generated inside the cylinder 22, and the opening end 22a is opened downward, so
(Pressure Capo) 22b, Raindrops, dirt, dust, etc. do not enter into the pressure derivation tube 23. Furthermore, even if raindrops or the like adhere to the pressure boat 22b in a windless state, they will be pulled out by the negative pressure within the cylinder 22 generated by the blowing of the wind.

Fig. 5 also shows the results of measuring pressure in the rain with raindrops. The rainfall at this time was 4.2 am/l1lin. As shown in FIG. 5, there is a slight difference in the negative pressure inside the cylinder 22 when it is raining and when it is not raining, but this is to the extent that it does not affect the actual measurement of wind speed. Therefore, in the above-mentioned embodiment, raindrops etc. do not enter the pressure boat 22b, and the wind speed can be detected and measured almost accurately even in rainy and non-rainy conditions, so it has excellent weather resistance, especially raindrop resistance. I can say that it is.

Moreover, since the end face of the open end 22a of the pressure detection cylinder 22 is parallel to the flow path plate 17.18, the end face of the open end 22a of the cylinder 22 is always parallel to the air flow. , the negative pressure inside the cylinder 22 does not depend on the wind direction but only on the wind speed. Therefore, the wind speed in all directions can be easily and accurately detected without having to separately measure each wind speed component of a specific wind direction and then detect the wind speed by combining these measured values as in the conventional method.

Next, the measurement circuit of this example is shown in FIG. The pressure detector 22 uses a semiconductor pressure sensor. The electronic control unit (ECU) 40 includes an analog power source 41. Digital power supply 42. Amplifier/filter circuit 43-1. A/D
Amplifier/filter unit 43 consisting of converter 43-2
．． D/A converter 44. and microcomputer 45
It is made up of. The power terminal 40 of the electronic control unit) 40. -1.40-2 is supplied as a constant voltage current by the analog power source 41 to the semiconductor pressure sensor 24 through the output terminal 40-3.40-4. Further, the analog power supply 41 is connected to the amplifier/filter unit 43. A constant voltage current is also supplied to the digital power supply 42. A digital power supply 42 supplies operating current for the microcomputer. Negative pressure indicating the wind speed detected by the wind speed detection cylinder 22 is electrically converted by the semiconductor pressure sensor 24. The output voltage of the semiconductor pressure sensor 24 is input to the amplifier/filter unit 43 through the input terminal 46 of the electronic control unit 40 . Amplifier/filter unit 43
The amplified and digitized signal is calculated by the microcomputer 45, and as a result is passed through the D/A converter 44 and taken out from the output terminal 47 as a wind speed output.

Next, a method of calculating wind speed in this embodiment will be explained. First, the relationship between the wind speed and the output of the semiconductor pressure sensor 24 is determined in advance by verification, and a one-dimensional map like the seventh one is stored in a memory. FIG. 8 is a calculation flowchart for wind speed measurement. The calculation starts from step 50. In step 51, the output is read by the semiconductor pressure sensor 24 based on the negative pressure inside the wind speed detection cylinder 22. In step 52, based on the data read in step 51,
Calculate the wind speed by following the map shown in Figure 7.

It should be noted that since the map created by the verification has discrete map points, interpolation calculations are performed between the map points. In step 53, the calculated wind speed is output, and the process returns to step 51 to perform the next measurement.

In the above embodiment, a semiconductor pressure sensor is used to measure the negative pressure inside the cylinder due to the wind speed, but any other sensor may be used as long as it can detect gas pressure.

In the above-described embodiment, the pressure inside the wind speed detection cylinder 22 is transmitted to the semiconductor pressure sensor 2 in the support case 11 through the pressure derivation tube 23 and the antenna rod 10.
However, the semiconductor pressure sensor 24 is connected to the upper case part 13.
The pressure signal from this sensor may be derived via a lead wire as a configuration in which the pressure signal is housed in the sensor.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment in which the current velocity measuring device of the present invention is applied to a wind speed sensor provided on an antenna rod, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 1st
4 is an enlarged sectional view of the main part of the wind speed sensor shown in FIG. 1, and FIG.
6 is a configuration diagram showing the measurement circuit, and FIG. 7 is a map stored in the memory in the microcomputer (45). FIG. 8 is a map characteristic diagram showing the relationship between the measured pressure and the calculated wind speed value. FIG. 8 is a flowchart showing the calculation within the microcomputer (45). 17.18... Channel plate, 22... Wind speed detection cylinder, 2
2a... Open end of wind speed detection cylinder, 22b... Pressure port 523... Pressure derivation tube, 24... Semiconductor pressure sensor.

Claims (2)

[Claims] (1) A cylindrical member having a cylindrical shape with an open end at one end, the outer periphery of the open end facing downward, and disposed parallel to the flow of fluid; and the interior of the cylindrical member. A flow velocity measurement device comprising: a pressure detection means for generating a pressure signal according to the pressure of the pressure detection means; and a flow velocity calculation means for receiving the pressure signal from the pressure detection means and calculating a flow velocity from the pressure signal. (2) The cylindrical member is provided with the outer periphery of the open end parallel to the upper flow path plate of two parallel flow path plates provided along the flow path through which the fluid flows. A flow rate measuring device according to claim 1.