JP3032513U - Hot wire anemometer - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To achieve compatibility between measurement probes of the same type or between different measurement probes and to reduce measurement error as much as possible in one measuring instrument main body. To be able to. SOLUTION: A single or a plurality of different measurement probes are provided with a preamplifier for correcting a characteristic curve showing a relationship between wind speed and output voltage in each measurement probe into an approximate straight line, and the characteristic curve of the measurement probe. At least 3 correction points of the correction circuit including the maximum value point and the minimum value point
Provide more than one place.

Description

[Detailed description of the device]

[0001]

[Technical field to which the device belongs]

 The present invention relates to a constant temperature difference type anemometer used for working environment, building management and the like.

[0002]

[Prior art]

 In recent years, constant-temperature-difference hot-wire anemometers (hereinafter referred to as "hot-wire anemometers") have become widespread not only in work environments and building management but also in a wide range of fields such as building air conditioning, clean rooms, and aeronautical engineering. As a hot-wire anemometer, its accuracy, operability, and adaptability to respond to a failure are required. As a conventional hot-wire anemometer, as shown in FIG. 11, one end of a wind speed sensor d including a bridge circuit 31 having a feedback amplifier 30 is connected to an A / D converter 33 via an amplifier 32. The temperature sensor e is connected to the A / D converter 33 via the amplifier 34, and the output from the A / D converter 33 is output via the input interface 35 to the calculating means 36 and the wind speed value reading means 37. Is provided to the central processing unit 38, which has a memory 39 for storing the characteristic curve of the wind speed / output voltage or its conversion calculation formula, and the output of the central processing unit 38. Is given to the display 41 via the output interface 40, and there is a display 41 which simultaneously displays the temperature and the wind speed (see Japanese Patent Laid-Open No. 4-332867). . Although not shown in the drawing as a specific device, it includes a detection unit equipped with a wind speed sensor d and a temperature sensor e, a cable for transmitting a signal from the detection unit, and a connector for connecting the cable and the measuring instrument body. It consists of a measuring probe and a measuring instrument that processes and displays the signal from the measuring probe. In addition, there are various types of measurement probes according to the purpose of measurement of wind speed and the measurement location, and each probe is used in combination with a dedicated measuring instrument body corresponding to each measurement probe.

[0003]

In the conventional hot-wire anemometer, it is necessary to select the measurement probe according to the measurement purpose and the measurement location and prepare the measuring instrument main body according to the measurement probe. However, there was a problem in that there was no compatibility between the same type of measurement probe and between different types of measurement probes for a single instrument main body. That is, FIGS. 7 to 10 show the shape of the tip of a typical measuring probe. FIG. 7 is called a keel type, FIG. 8 is called an oval type, FIG. 9 is called a porous type, and FIG. 10 is called a ball type. The keel-type measuring probe is provided with a horizontal cylindrical guide 2 having open both sides at the upper end of a cylindrical supporting rod 1, in which a sensor 3 for measuring the wind speed is provided. It is mainly used for high-precision air flow measurement in the low wind speed region such as architectural and clean rooms. The oval-type measuring probe has a pair of vertically elongated windows 4 facing each other in the diametrical direction of the distal end of a cylindrical support rod 1 whose upper end surface is closed, and measures the wind speed therein. A sensor 3 is provided and is mainly used for measuring a wide range of wind speeds from a low wind speed region to a high wind speed region. A porous type measuring probe is mainly composed of a cylindrical support rod 1 having a closed upper end surface, in which a large number of small holes 5 are formed on the peripheral surface of the distal end portion, and a sensor 3 is arranged therein. Used for measurement in high wind speed range. The ball-type measuring probe has a cylindrical support rod 1 having a conical upper end surface on which a thin column 6 is erected at the center of the upper end thereof, and a small spherical sensor 3 is provided at the tip thereof. It is used to measure the wind speed from.

Therefore, the measurement probe and the dedicated measuring instrument main body are selected from these depending on the application, but the measuring probe and the measuring instrument main body are always used as a pair, and the measuring probe is damaged. However, if it becomes necessary to replace the measuring probe, it is not easy to replace the measuring probe even if the measuring instrument body and the corresponding measuring probe are of the same type. Furthermore, there was no compatibility between the probes for different types of measurement.

That is, since the measurement probes have different shapes, sensor materials, etc., the heat dissipation coefficients are different, and the characteristic curves showing the relationship between the wind speed and the output voltage are also different for each measurement probe. In these cases, the measurement probe and its dedicated measuring instrument body must be sent together to the manufacturer or calibration facility that has the calibration equipment, and the measurement probe must be replaced and the measuring instrument body must be calibrated. There was a great deal of complexity in dealing with such a failure. Further, in the anemometer of the conventional technique, the measurement probe and the measuring instrument main body are combined, and the output voltage value of the measuring probe is stored in advance as the memory of the measuring instrument main body, and this is stored in the measuring probe during measurement. It is called according to the output voltage value and calculated as the wind speed value. The relationship between the wind speed and the output voltage value is expressed by Equation 1.

[0006]

(Equation 1) Then, this characteristic curve is an upwardly convex curve as shown in FIG. Therefore, there is a problem that the measurement error becomes large in the measurement near the midpoint of the measurement range.

[0007]

[Means for Solving the Problems]

 The present invention is not one in which the relationship between the measuring probe and the measuring instrument main body is fixed as in the above-mentioned conventional one, and not only the measuring probe of the same type but also a different type of measuring instrument body can be used. The purpose is to obtain a hot-wire anemometer that can be combined with a measurement probe to show the relationship between the output of the measurement probe and the voltage to multiple single or different measurement probes in the hot-wire anemometer. A preamplifier that corrects the characteristic curve into a curved line that is close to a straight line is provided, and the correction points of the characteristic curve correction circuit of the measurement probe are provided in at least three locations including the maximum value point and the minimum value point. In addition, the measuring probe is provided with a plurality of connector pins, the receptacle of the measuring instrument body is provided corresponding to the pins, and the conducting potentials of the connector pins are different. It is characterized in that made different for each measuring probe Tsu.

As described above, by providing the measurement probe with the preamplifier that corrects the characteristic curve of the measurement probe and providing a plurality of correction points of the characteristic curve correction circuit of the measurement probe, Therefore, the compatibility between measurement probes of the same type or different measurement probes can be achieved, and the measurement error can be minimized.

[0009]

[Embodiment of device]

 The hot-wire anemometer of the present invention comprises a sensor for detecting wind speed, a cable for transmitting a signal from the sensor, and a single or different plurality of measuring probes each including a connector for connecting the cable and the measuring instrument main body, and a measuring probe. It is equipped with a receptacle to which the connector of the probe for measurement is connected, and consists of the measuring instrument that processes the signal from the measuring probe and displays the measured value.

The connector of the measurement probe is provided with a preamplifier that corrects the characteristic curve showing the relationship between the output and voltage of the measurement probe to a curve close to a straight line, and the characteristics of the measurement probe. It is preferable that the correction points of the curve correction circuit are provided at a plurality of at least three points including the maximum value point and the minimum value point, and preferably three or more points in the middle of the maximum value point and the minimum value point. The above preamplifier may be provided at any position on the side of the measuring probe such as a support rod or a grip of the sensor, but it is preferable to provide it in the connector for the configuration and handling of the device.

The measuring instrument body has a receptacle part for identifying the type of various measurement probes or correction output, and the analog signal from the preamplifier identified and selected by the receptacle part is A / D converted. It is converted into a digital signal by the converter and input to the central processing unit. In the central processing unit, the calculation formula for the measurement probe corresponding to the input signal is read from the read-only memory that stores and registers the calculation formula for linearizing the correction curve for each measurement probe in advance. The digital signal output corresponding to the readout and flow velocity is calculated and linearized, and the numerical value of the processed signal is displayed on the display.

Any known means may be used as a means for identifying the type of the various measurement probes and the correction output, but it is easy to distinguish the measurement probe and call the memory on the measuring instrument main body side. To achieve this, it is advisable to provide a plurality of pins for the connector of the measurement probe, provide a plurality of receptacles corresponding to the pins on the measuring instrument body, and make the energization positions of the pin and the receptacle different for each measurement probe.

[0013]

【Example】

 An embodiment of a hot-wire anemometer according to the present invention will be described with reference to the drawings. 1 is a block diagram showing the overall configuration, FIG. 2 is an explanatory view of the apparatus of FIG. 1 including a measuring probe and a measuring instrument main body, FIG. 3 is an explanatory view of a pin portion of a connector, and FIG. 4 is a measuring instrument main body. FIG. 5 is an explanatory diagram of the receptacle portion, FIG. 5 is a characteristic curve diagram showing the relationship between wind speed and output voltage, and FIG. 6 is a corrected characteristic curve diagram of FIG.

2 to 4, the detecting portion of the measuring probe A has the same structure as the detecting portion of the conventional measuring probe of the keel type, and the grip portion 7 of the support rod 1 and the connector 8 are provided. It is connected by a cable 9 and a preamplifier 10 described later is built in the connector 8. The measuring instrument body B has a receptacle portion 12 to which the pin portion 11 of the connector 8 of the measurement probe A is connected, and a data display portion 13 and various switch portions 14. The pin portion 11 of the connector 8 is provided with a large number of pins 11a, and the receptacle portion 12 of the measuring device body B is provided with the same number of receptacles 12a facing the pins 11a. The energization position in the many pins 11a of the connector 8 is made different for each type of the measurement probe A, and only by connecting the connector 8 is the type of the measurement probe A and the characteristic curve on the measuring instrument main body B side. The correction output can be identified.

The circuits on the measurement probe A side and the measuring instrument body B side will be described with reference to FIGS. 1 to 6. On the measurement probe A side, a bridge circuit C is formed by the platinum element 15 for temperature detection, the temperature-dependent resistor 16, and the resistors 17 and 18, and the outputs from both ends of the bridge circuit C 2 enter an amplifier 19. Is constantly monitored so that the electric power corresponding to the heat radiation amount due to the flow is compensated from the calorific value of the platinum element 15 for flow velocity detection, and is fed back to the bridge circuit C so as to compensate for the compensated amount. Further, the signal from the bridge circuit C becomes an electric signal output with respect to the change of the flow velocity and is amplified by the amplifier 20. At this time, the electric signal output becomes a characteristic curve as shown in FIG. 5, which shows the correlation with the flow velocity.

The electric signal output is input to the preamplifier 21. The preamplifier 21 configures five correction points c including the minimum value a and the maximum value b in the characteristic curve, and is converted into a correction curve corrected by this (BSL correction circuit). Consists of. The flow velocity output converted into the correction curve enters the measuring instrument main body B side via the pin 11a on the measuring probe A side and the receptacle 12a on the measuring instrument main body B side. As described above, different measurement probes A or addresses (energized positions) corresponding to the correction curves are assigned to the pins 11a and the receptacles 12a, respectively, and different measurement probes A are measured. When connected to the instrument body B, the type of the measurement probe A or the correction output can be identified by collating with the address assigned to the pin 11a.

The analog signal from the preamplifier identified and selected by the receptacle unit 12 is converted into a digital signal by the A / D converter 22 and input to the central processing unit 23. In the central processing unit 23, from the read-only memory 24 in which the calculation formula for linearizing the correction curve for each measurement probe is stored and registered in advance, the calculation formula of the measurement probe corresponding to the input signal. Is read out, the digital signal output according to the flow velocity is arithmetically processed and linearized, and the numerical value of the processed signal is displayed on the display 25. Further, the central processing unit 23 is provided with a D / A converter 26 for enabling recording to an ordinary analog recorder and the like, and a digital dedicated output circuit 27 for connecting to a printer or a computer.

[0018]

[Effect of device]

 Since the present invention is implemented in the form described above, it has the following effects. Since the measurement probe is equipped with a preamplifier that corrects the characteristic curve showing the relationship between wind speed and output voltage to an approximate straight line, if the measurement probe fails or is damaged, only the measurement probe is used. It can be replaced and does not need to be calibrated along with the instrument itself, which makes the equipment easier to maintain and saves time and money.

Since the correction points in the characteristic curve correction circuit of the preamplifier are provided at a plurality of locations including at least three points including the maximum value point and the minimum value point, the characteristic curve peculiar to the measurement probe can be obtained. Since the curve is close to a straight line, the measurement error can be minimized and the measurement accuracy can be remarkably improved by providing a large number of correction points.

The measuring probe is provided with a plurality of connector pins, and the receptacle of the measuring instrument body is provided corresponding to the pins, so that the energizing position of the connector pins can be made different for each of the different measuring probes. This makes it easy to identify the measurement probe and call up the memory on the measuring instrument side, and multiple measuring probes can be used on one measuring instrument body, providing high compatibility and easy measurement of various wind speeds. And it can be done at low cost.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of a hot-wire anemometer according to the present invention.

FIG. 2 is an overall explanatory view of the device of FIG. 1 including a measuring probe and a measuring device main body.

FIG. 3 is an end view of the pin portion of the connector of the measurement probe.

FIG. 4 is an end view of the receptacle portion of the measuring instrument body.

FIG. 5 is a characteristic curve diagram showing the relationship between wind speed and output voltage.

FIG. 6 is a characteristic curve diagram showing the relationship between the output voltage corrected at a plurality of points and the wind speed.

FIG. 7 is an enlarged explanatory view of a tip portion of a keel type measurement probe.

FIG. 8 is an enlarged explanatory view of a tip portion of an oval type measurement probe.

FIG. 9 is an enlarged explanatory view of a tip portion of a porous type measurement probe.

FIG. 10 is an enlarged explanatory view of a tip portion of a ball-type measuring probe.

FIG. 11 is a block diagram showing the overall configuration of a conventional hot-wire anemometer.

[Explanation of symbols]

 8: Connector 10: Preamplifier 11a: Pin 12a: Receptacle a: Maximum value point b: Minimum value point c: Correction point A: Measuring probe B: Measuring instrument body

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[Procedure amendment]

[Submission date] July 23, 1996

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Explanation of Codes] 8: Connector 10: Preamplifier 11a: Pin 12a: Receptacle a: Minimum value point b: Maximum value point c: Correction point A: Measurement probe B: Measuring instrument body

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

Claims (4)

[Scope of utility model registration request] 1. A preamplifier (10) for correcting a characteristic curve showing the relationship between the output and voltage of the measuring probe (A) into an approximate straight line is provided on the measuring probe (A) in a constant temperature difference type hot wire anemometer. A hot-wire anemometer characterized by 2. The measurement probe (A) is a plurality of measurement probes (A) of different types, and the characteristic curve of each measurement probe (A) is added to each measurement probe (A). Preamplifier that corrects to an approximate straight line (10)
The hot-wire anemometer according to claim 1, wherein the hot-wire anemometer is provided. 3. A correction point (c) in the characteristic curve correction circuit of a preamplifier (10) is provided at a plurality of locations including at least three points including a maximum value point (a) and a minimum value point (b). The hot-wire anemometer according to claim 1. 4. A plurality of pins (11a) of a connector (8) of a measuring probe (A) are provided, and the pins (1)
1a) corresponding to the receptacle (1) of the measuring instrument body (B)
2a) is provided, and the energization position of the pin (11a) of the connector (8) is made different for each of a plurality of different measurement probes (A). Total.