JPH0277620A - Flow velocity detector - Google Patents

Abstract

PURPOSE:To precisely measure a fluid and to enhance response by arranging hot only a main hot wire but also a compensating hot wire to a support frame. CONSTITUTION:A support frame 1 is arranged in a desired pipeline, and main hot wires 4, 4 and compensating hot wires 7, 7 are connected to a measuring apparatus by an electrical circuit to allow a fluid to be measured to flow through the pipeline. Whereupon, the set temps. of the hot wires 4, 4, 7, 7 are finely changed by the flow velocity of the fluid and the resistance of the hot wires 4 themselves are changed. Subsequently, since a feedback current flows so as to follow the temp. change thereof, said temp. change is detected. Since this temp. change is sensitively given as the change of the resistance values of the hot wires 4, 4, 7, 7 by the flow velocity of the fluid, flow velocity or a flow rate can be easily measured.

Description

[Detailed description of the invention] This invention relates to a flow velocity detector using a hot wire.

In general, King's equation is known, which states that the flow rate or flow rate of a fluid can be measured by arranging a hot wire in a fluid flow path and measuring the temperature change of the hot wire.

The present invention relates to a flow velocity detector using the above King's equation, and an object of the present invention is to provide a novel flow velocity detector that has a simple configuration and is capable of measuring flow rates over a wide range of applications.

That is, the present invention is characterized by having an annular support frame that can be easily inserted into a desired pipe line, and in which the required number of main heating wires (one, two, or more) is attached to the support frame. It is possible to measure the flow velocity at all locations that match the flow velocity distribution of the fluid flowing through the pipeline by installing a compensator on the pipe wall of the pipeline or at a location recessed slightly inside the pipe wall. It is an object of the present invention to provide a flow velocity detector capable of producing a highly accurate current velocity meter 1n11 equipped with a hot wire.

In addition, the compensating heating wire attached to the main heating wire is configured to have the same shape, the same size, and the same material as the heating wire, or to have the same resistance value. To provide a detector.

Next, an embodiment of the flow velocity detector according to this invention will be described.

Reference numeral 1 denotes an annular support frame having an outer shape that can be fitted to fit the size of the pipeline 2 to be installed, 3 a fluid passage hole in the support frame 1, and 4, 4 opposite positions of the support frame l. It consists of two main heating wires stretched in an inverted π shape across the fluid passage hole, and is made of platinum or other temperature sensing resistor. 5 is a terminal plate to which one ends of the two main heating wires 4, 4 are commonly connected; 6, 6;
is a terminal board to which the other ends of the main heating wires 4, 4 are connected, and these terminal boards 5, 6.6 are connected to the heating wires so that they are hardly affected by expansion and contraction due to thermal changes in the main heating wires 4.4. Same material as the material,
For example, it is made of platinum foil material.

It is preferable.

Reference numeral 7.7 denotes two compensating hot wires stretched along grooves 8, 8 bored in the same part of the mounting frame 1 on the sides of the two main hot wires 4.4. It is desirable that the terminals 9, 9, 9.9 are made of platinum foil material or the like so that both ends are similarly not affected by heat.

(See FIG. 1) The hot wire 7.7 for Nn compensation is useful for measuring the ambient temperature of the fluid flowing through the pipe line 2, and may be a thermistor as shown in FIG.

In short, it is helpful to make the main heating wires 4, 4 the same shape, the same size, and made of the same material, or to configure them with the same material with the same resistance value, to improve measurement accuracy.

Although the compensation heating wire 7.7 is not shown, it is made of the same material and having the same shape and size as the main heating wires 4, 4 as described above.
In some cases, it may be placed in a bent shape along the inner circumferential surface of the mounting frame 1 without forming it.

FIG. 4 shows one of the main heating wires 4.4 and the compensation heating wire 7.4.
7, electrically detects temperature changes in the main hot wire 4 and the compensation hot wire 7 that are affected by fluctuations in the flow velocity of the fluid flowing in the flow path 2. While measuring, the constant temperature of the hot wire 4.7 can be maintained by the feedback circuit 12 using the amplifier 111 and the transistor 11, and by the power source Es. Since the amount of electricity returned from the feedback circuit 12 is proportional to the amount that actually flows through the pipe 2, the flow rate or flow fft
can be measured. Therefore, if the bridge circuit P1 intensifier 1O, transistor 11, and power source Es are provided corresponding to the number of main heating wires 4 and compensation heating wires 7, and the average amount of feedback electricity of each feedback circuit 12 is obtained, the conduit 2 can be A measurement of the average flow velocity or average flow fil is carried out. Here, the main heating wire and the compensation heating wire may each be used as a pair, and may be configured with independent power supplies and bridge circuits. That is, as shown in FIG. 5, two constant temperature bridge circuits P each consisting of one of the main heating wires 4, 4 and one of the compensation heating wires 7, 7 are provided, and the fluid flowing in the flow path 2 is While electrically detecting and measuring temperature changes in the main heating wire 4 and the compensation heating wire 7 affected by fluctuations in flow velocity, the feedback circuit 12 and the power source Es I+ Es
t makes it possible to maintain a constant temperature of the heating wire 4.7. Since the amount of air returned by the feedback circuit 12 is proportional to the amount actually flowing through the pipe 2, the flow velocity or flow rate can be measured.

Therefore, the bridge circuit P multiplier 10 and transistors correspond to the number of main heating wires 4 and compensation heating wires 7! 1?
[A source ES++ES1 is provided, and each feedback circuit 1
The average flow velocity or average flow rate flowing through the pipe line 2 can be measured from the output obtained by applying the feedback electricity LIT of 2 to the adder/intensifier I4.

[hereinafter], two embodiments of this invention have been described,
In this invention, the number of main heating wires installed does not need to be two as mentioned above, but if you want to measure the flow velocity distribution more accurately, it is preferable to increase the number, and the compensation heating wires can also be installed over the entire pipe wall area. If you want to measure the temperature distribution, you can increase the number. Note that the reference numeral 13 in the figure indicates a conducting wire.

Since this invention has an inclined configuration, the support frame 1 is installed in the desired pipe line 2, and each hot wire 4, 4, 7, 7 is connected to the measuring device by an electric circuit to flow the fluid to be measured. , hot wire 4,4
, 7.7 changes slightly depending on the flow velocity of the fluid, and the resistance of the hot wire itself changes, so a feedback current flows to follow the temperature change, so the temperature change is detected. Since this temperature change is sensitively given as a change in the resistance value of the hot wire 4.4.7.7 depending on the flow velocity of the fluid, the flow velocity or flow lit can be easily measured based on King's equation.

As described above, in this invention, not only the main heating wire but also a compensation heating wire is arranged in the support frame, so that most of the flow velocity of the main fluid can be detected by the main heating wire, and the flow rate of the fluid in the pipe can be detected by the main heating wire. The ambient temperature is maintained perfectly by means of a compensating hot wire.

Therefore, it has many features such as being able to precisely measure the fluid, and having extremely good responsiveness because the flow velocity is measured by detecting changes in flow velocity based on changes in the temperature of the hot wire.

In addition, the main heating wires and compensation heating wires above - are each used as a pair, and they are configured with independent power supplies and bridge circuits, so mutual interference due to load fluctuations of each main heating wire is avoided, and high accuracy is achieved. This also has the effect of making measurement possible.

[Brief explanation of the drawing]

1 and 2 are perspective views showing two embodiments of the flow velocity detector according to the present invention, FIG. 3 is a cross-sectional view showing the state installed in a pipe, and FIGS. 4 and 5 are views of the present invention. FIG. 2 is an example of a constant temperature bridge circuit diagram connected to a flow rate detector. I ・・・・・・・・・・・・・・・Support frame 4.4 ・
...Two inverted π-shaped main heating wires 7.7 ...Two compensation heating wires 12 ...Feedback circuit Heisei 1
July 140 1. Display of the case Q/-Mer-Nin//Regarding the original patent application number 8721 of 1982 (procedural amendment submitted on March 14, 1980), filed on June 15, 1999. Patent application 2 prescribed in Article 53, Paragraph 4 of the Patent Entrance
Title of the invention: Flow velocity detector 3, person making the amendment.Relationship with the case: Applicant postal code: 161 Address: Shinjuku-ku, Tokyo" - 3-10-8-5 Ochiai, "Claims of the specification subject to amendment" ” and “Detailed Description of the Invention” column 6, Contents of amendment (1) The claims are amended as shown in the attached sheet. (2) [Consideration 1 on page 3, line 5 of the specification is amended to read ``Invention 1. Claims: A ring-shaped support frame attached to a pipeline, and one or more main heating wires attached to the support frame. A compensating hot wire is stretched across the fluid passage hole and is made of the same material and has the same shape as the main hot wire,
The main heating wire and the compensation heating wire are each of the same size, and are arranged along the fluid passage hole of the support frame on the inner wall of the pipe or slightly inside the pipe, and the main heating wire and the compensation heating wire are each used as a pair, and are connected to a power source and a bridge that are independent of each other. A flow velocity detector comprising a circuit, and configured to detect the flow velocity of the fluid flowing through the pipe line as a thermal change in the main heating wire and the compensation heating wire.

Claims (4)

[Claims] (1) One or more main heating wires are stretched across the fluid passage holes of the support frame in an annular support frame attached to the conduit, and a compensating heat wire is stretched across the fluid passage holes of the support frame. A flow velocity detector is disposed along the inner wall of the pipe or slightly inside the pipe, and detects the flow velocity or flow rate of the fluid as a thermal change in the main heating wire and the compensation heating wire. (2) The flow velocity detector according to claim 1, wherein the compensating hot wire is made of the same material, has the same shape, and has the same size as the main hot wire. (3) The flow velocity detector according to claim 1, wherein the compensation heating wire has the same resistance value as the main heating wire. (4) The flow velocity detector according to claim 1, wherein the main heating wire and the compensating heating wire are each used as a pair, and are configured with independent power supplies and bridge circuits.