JP3410562B2 - Temperature / wind speed measurement device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature / wind velocity measuring device capable of simultaneously measuring a wind velocity and its temperature.

[0002]

2. Description of the Related Art Conventionally, a hot-wire anemometer using a bridge circuit has been widely used as an anemometer. As shown in FIG. 2, the hot wire anemometer uses, for example, a platinum wire 1 as a temperature sensitive element, and the platinum wire 1 and the resistors R1 and R2 and the temperature sensitive resistor 2 are used.
The bridge circuit 3 is configured by the (resistance value Rc), and the bridge circuit is balanced with a resistance value at which the platinum wire 1 reaches a predetermined temperature. The connection points of the resistor R1 and the platinum wire 1 and the resistor R2 and the temperature-sensitive resistor 2 of the bridge circuit 3 are respectively connected to a pair of input ends of the feedback amplifier 4, and the feedback amplifier 4 feeds back to the bridge circuit 3 to make the platinum wire 1 To generate heat to bring the bridge into equilibrium. Then, the wind velocity U passing through the platinum wire 1 was measured by the following formula according to the voltage Vtop across the bridge circuit 3. _{^{Vtop 2 / R H = (a}} + b√U) (T P -T) ··· (1) where R _H is the resistance of platinum wire 1, a, b are constants, T _P is the temperature of the platinum wire 1, T Is the wind temperature. The resistance value of the platinum wire is shown by the following equation. _{R H = R H0 (1 +} αT P) ··· (2) R H0 resistance value at 0 ° C., alpha is about 0.004. If it thus temperature-sensitive resistor 2 is provided to the bridge circuit, except for the effects of the wind temperature the temperature difference between the platinum wire 1 even after changing the air temperature T (T _P -T) is always constant The wind speed can be measured. Such a wind velocity measuring method is called a constant temperature difference type.

There is also known a constant temperature anemometer in which a fixed resistor is used instead of the temperature sensitive resistor 2 to form a bridge circuit, and the wind velocity is measured while keeping the temperature of the platinum resistor constant. Since the constant temperature anemometer does not remove the influence of the wind temperature, a separate temperature sensor is required, and it is necessary to correct the obtained wind speed value by the temperature obtained from the temperature sensor and output it as the wind speed value. In this case, since the sensitivity changes when the air temperature changes, there is a drawback that temperature compensation cannot be performed in a wide range.

On the other hand, when the temperature of the wind is measured at the same time as the wind speed, a temperature sensor such as the temperature sensitive resistor 5 is provided independently of this.
(Resistance value Rt) is provided, and it is necessary to convert this output into a temperature signal by the temperature sensor 6 including an amplifier and output it.

[0005]

As described above, in the conventional constant temperature difference type wind velocity measuring device and wind temperature measuring device, in addition to the platinum wire 1 for measuring the wind velocity as a temperature sensitive element, the temperature compensating device There is a problem that the temperature sensitive resistance 2 and the sensitivity resistance 5 for measuring the air temperature are required, and three sensor elements are required.

The present invention has been made in view of the above-mentioned conventional problems, and it is a technical object to make it possible to simultaneously measure the wind temperature and the wind speed by using two temperature sensitive elements. .

[0007]

According to a first aspect of the present invention, there is provided a first temperature sensitive element, a temperature sensor section for outputting temperature information, a first fixed resistor and a second temperature sensitive element. Together with a first series connection body, a feedback amplifier in which the middle point of the first series connection body is connected to one input end, the first series connection body, a virtual second fixed resistor and The voltage at the midpoint of the second series connection of the virtual bridge formed by the virtual second series connection including the temperature compensation element is calculated based on the temperature information obtained from the temperature sensor and the output of the feedback amplifier. And a wind speed calculation unit that calculates a wind speed on the basis of the output of the feedback amplifier, and a bridge end voltage calculation unit that outputs to the other input end of the feedback amplifier.

In the invention of claim 2 of the present application, the bridge end voltage calculation unit calculates the resistance value of the virtual temperature compensation element based on the temperature information obtained from the temperature sensor, and the temperature / resistance value conversion unit. The resistance value obtained from the resistance value conversion unit is R
c, the resistance value of the virtual second fixed resistor is R2, and the output of the feedback amplifier is Vtop, R2 · Vtop / (Rc
+ R2), and a subtractor for subtracting the output of the divider from the output of the feedback amplifier, and the output of the subtractor is output to the other input end of the feedback amplifier. It is what

[0009]

According to the present invention having such features, the first
The temperature information is output by the temperature sensor and the temperature sensor. Further, a first series-connected body using the second temperature sensitive element as a wind speed sensor is constructed. Assuming a bridge circuit between the first series connection body and the second series circuit including the second fixed resistance and the temperature compensation element, the voltage at the midpoint of the second series connection body of the bridge circuit is the temperature information. It can be calculated based on. Therefore, the midpoint voltage is calculated by the operation at the bridge end voltage computing unit, and the midpoint voltage of the first series connection body is input to the feedback amplifier,
The wind speed can be measured by a normal constant temperature difference type wind speed measuring device. Then, the temperature information can be simultaneously measured by the temperature sensor.

[0010]

1 is a block diagram showing the overall construction of a temperature / wind velocity measuring device according to an embodiment of the present invention. In the figure, 10 is a temperature-sensitive resistor for temperature detection, and the temperature detection unit 1
1 is connected. The temperature detector 11 uses this temperature sensitive resistor 1
The temperature information T (° C.) is detected and output based on the resistance value Rt of 0, and the output is the temperature / resistance value conversion unit 1.
Entered in 2. The temperature / resistance value conversion unit 12 converts the temperature data of the temperature information T (° C.) into the data of the resistance value Rc of the temperature sensitive resistor 2 in the bridge circuit 3 shown in the conventional example described above. In this embodiment, the second fixed resistor R2 and the temperature-sensitive resistor for temperature compensation are not used, but a series connection body of these elements is virtually connected in parallel to the fixed resistor R1 and the platinum wire 1 to form a bridge circuit. As 3 is configured,
The resistance value Rc of the temperature sensitive resistor 2 and the voltage at the middle point are calculated. That is, the resistance value Rc of the temperature sensitive resistor 2 which is a temperature compensation element.
Is given by the following equation. Rc = Rco (1 + αta) (3) Rco is a resistance value of the temperature sensitive resistor 2 at 0 ° C., and α is a temperature coefficient. Here, it is assumed that α is set to the same value as the temperature coefficient of the platinum wire 1 which is the wind speed sensor. The resistance value data is given to the division unit 13. The bridge top voltage Vtop of the bridge circuit described above is simultaneously input to the divider 13. The division unit 13 is assumed to perform the following calculation. R2 · Vtop / (Rc + R2) (4) Note that R2 is the resistance value of the virtual second fixed resistor.

The output of the division unit 13 is input to the subtraction unit 14 formed of an operational amplifier. Temperature / resistance conversion unit 1
2. The division unit 13 and the subtraction unit 14 form a bridge end voltage calculation unit that generates the output V ₊ at the positive end of the feedback amplifier of the bridge circuit according to the conventional example described above by the following formula. V ₊ = {1-R2 / (Rc + R2)} Vtop (5) The output of the subtracting section 14 is connected to the non-inverting input terminal of the feedback amplifier 15. The inverting input terminal of the feedback amplifier 15 is connected to a first fixed resistor R1 that divides the output terminal and a first series connection body including a platinum wire 1 that serves as a wind speed sensor element. The feedback amplifier 15 has the same function as the feedback amplifier 4 according to the conventional example, and the output of the feedback amplifier 15 is output to the division unit 13 and the wind speed calculation unit 16. The bridge top voltage Vtop is output to the division unit 13, the subtraction unit 14, and the wind speed calculation unit 16. The wind speed calculation unit 16 calculates and outputs a wind speed value based on the bridge top voltage Vtop.

Next, the operation of the temperature / wind velocity measuring device according to this embodiment will be described. First, the temperature detection unit 11 outputs temperature information T (° C.) indicating the measurement symmetrical wind temperature. Then, this temperature is converted into the resistance value data in the bridge circuit corresponding to this temperature by the temperature / resistance value conversion unit 12 as in the above-mentioned formula (2). Then, the division unit 13 and the subtraction unit 14 generate a voltage to the non-inverting input terminal of the feedback amplifier 15 based on the resistance value Rc as shown in the equation (5). Thus, instead of the resistor R2 and the temperature sensitive resistor 10 of the bridge circuit, the temperature sensitive resistor Rt is connected to the block 11
15 to 17 are used as inputs to the feedback resistor to virtually form a bridge circuit.

With such a structure, the present invention provides such excellent effects. First, as the temperature-sensitive resistance (wind speed sensor), only the platinum wire 1 and the temperature-sensitive resistance Rt can be used to measure the temperature and the wind speed at the same time. If the conversion coefficient α of the temperature / resistance value conversion unit 12 is set to the same value as that of the platinum wire, a constant temperature difference type can be obtained and the temperature difference between the platinum wire and the wind temperature can always be made constant. Therefore, the temperature difference becomes constant over a wide range, and temperature compensation can be easily performed.

The conversion coefficient α of the temperature / resistance value conversion unit 12 can be set to 0. In this case, the voltage level of the non-inverting input terminal of the feedback amplifier 15 is constant depending on the temperature, and the temperature of the platinum wire 1 serving as an equivalent bridge circuit is also constant, that is, a constant temperature type wind velocity measuring device. In this case, it is necessary to correct the wind speed value obtained by the wind speed calculation unit 16 based on the temperature data obtained by the temperature detection unit 11 as in the case of a normal constant temperature anemometer.

As described above, according to the present invention, the constant temperature type and the constant temperature difference type can be arbitrarily converted by setting the conversion coefficient of the temperature / resistance value conversion unit 12.

In this embodiment, the temperature-sensitive resistor 10 is a platinum wire, but the temperature is not limited to the platinum wire, and the temperature can be measured using any temperature-sensitive element such as a thermistor or a thermocouple.

[0017]

As described in detail above, according to the present invention, the wind speed and its temperature can be simultaneously measured by the first and second temperature sensitive elements. In this case, it is possible to construct a wind velocity measuring device using a constant temperature difference type having a wide temperature compensation range without using the constant temperature type wind velocity measuring device that drives the second temperature sensitive element at a constant temperature. Is obtained.
In addition, the response speed of the temperature sensor circuit (temperature / resistance value conversion unit)
It is also possible to arbitrarily set the time constant of.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a temperature / wind velocity measuring device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional device for measuring wind speed and temperature.

[Explanation of symbols]

1 platinum wire 2,5,10 Thermal resistance 11 Temperature detector 12 Temperature / resistance conversion unit 13 Division 14 Subtraction unit 15 Feedback amplifier 16 Wind speed calculator

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Claims (2)

(57) [Claims] 1. A first temperature sensitive sensor having a first temperature sensitive element for outputting temperature information, a first fixed resistor and a second temperature sensitive element connected in series.
From the virtual second fixed resistance and temperature compensation element together with the first series connection body, a feedback amplifier in which the midpoint of the first series connection body is connected to one input end, A voltage at the midpoint of the second series connection body of the virtual bridge constituted by the virtual second series connection body is calculated based on the temperature information obtained from the temperature sensor and the output of the feedback amplifier. A temperature / wind speed measuring device comprising: a bridge end voltage calculation unit that outputs to the other input end of the feedback amplifier; and a wind speed calculation unit that calculates a wind speed based on the output of the feedback amplifier. 2. A temperature / resistance conversion unit, wherein the bridge end voltage calculation unit calculates a resistance value of the virtual temperature compensation element based on temperature information obtained from the temperature sensor, and the temperature / resistance conversion unit. When the resistance value obtained from the section is Rc, the resistance value of the virtual second fixed resistor is R2, and the output of the feedback amplifier is Vtop, R2.Vtop / (Rc
+ R2), and a subtraction unit that subtracts the output of the division unit from the output of the feedback amplifier, and outputs the output of the subtraction unit to the other input end of the feedback amplifier. The temperature / wind velocity measuring device according to claim 1, wherein