JPH032814Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an eddy current type current meter that measures the flow velocity of a conductive fluid to be measured based on eddy currents generated in the fluid to be measured.

FIG. 1 is a configuration explanatory diagram showing an example of a detection unit DET constituting the detection section of this type of device, in which CB is a coil bobbin, W _EX is an excitation coil wound around the coil bobbin CB, W _D1 , W _D2 is the excitation coil
This is a detection coil wound around a coil bobbin CB so as to sandwich W _EX .

The detection unit DET configured in this way is
Insert the coil bobbin CB into a guide tube (not shown) placed in the fluid so that the center axis of the coil bobbin CB matches the flow direction F of the conductive fluid to be measured.
When an alternating current signal is applied to W _EX , eddy currents are generated in this fluid. Note that depending on the fluid to be measured, the probe may be inserted directly into the fluid to be measured without being inserted into the guide tube. This eddy current is caused by the excitation coil W _EX
It can be roughly divided into two types: one is caused by the magnetic flux φ generated by the magnetic flux φ, and the other is caused by an electromotive force corresponding to the vector product of the magnetic flux φ and the flow velocity of the fluid. When the fluid moves at a certain flow velocity, the new magnetic flux generated by the latter eddy current mutually interferes with the main magnetic flux φ created by the exciting coil W _EX , and the magnetic flux distribution near the exciting coil W _EX occurs. is distorted from the shape shown by the second solid line φ to the shape shown by the dotted line φ'. Here, the amount Δφ by which the magnetic flux distribution is distorted corresponds to the flow velocity of the fluid to be measured. Signals e _{1 and} e ₂ corresponding to the magnetic flux interlinked with the detection coils W _D1 and W _D2 are generated, and the amount of distortion in the magnetic flux distribution can be determined by calculating the difference between the two signals e ₁ and e ₂ . Δφ,
In other words, the flow velocity of the fluid to be measured can be determined.

By the way, conventionally, when connecting such a detection unit to an external circuit, a twisted wire TW is used for each coil as shown in Fig. 3, and these twisted wires are connected to a flexible tube without being fixed to each other. FT, and this flexible tube FT is inserted into the guide tube WL.

However, with such a configuration, although the twisted wires can reduce electromagnetic induction noise to some extent, the positional relationship between the twisted wires may cause expansion or contraction of the constituent members due to temperature changes in the fluid to be measured, or the fluid flow of the fluid to be measured. Since the pressing force on the guide tube WL due to vibration changes over time, the magnitude of the residual electromagnetic induction noise also changes, making it difficult to obtain high resolution.

The present invention solves these conventional drawbacks, and is characterized by using metal sheath twisted wires as lead wires to each coil of the detection section, and fixing the metal sheaths of these lead wires to each other. .

Hereinafter, it will be explained in detail using the drawings.

FIG. 4 is a configuration explanatory diagram showing one embodiment of the present invention, and the same parts as in FIG. 3 are given the same reference numerals.

In FIG. 4, STW is a metal sheath twisted wire, and the metal sheaths of these twisted wires STW are fixed and integrated by, for example, brazing. The twisted wire STW in which the metal sheaths are fixed and integrated in this way is connected to the guide tube WL.
It is inserted directly into the interior of the body without using a conventional flexible tube. It has multiple twisted wires
By integrating the STW, the overall strength is increased, and there is no risk of bending within the guide tube WL.

According to this configuration, since the metal sheaths of the twisted wire STW are fixed and integrated, there is no possibility of expansion or contraction of the constituent members due to temperature changes of the fluid to be measured or vibrations of the fluid to be measured to the guide tube WL. Unlike conventional methods, the positional relationship between the twisted wires STW does not change significantly due to changes in pressing force over time, etc., and changes in electromagnetic induction noise caused by positional changes between the twisted wires are significantly reduced. be able to. Therefore, residual electromagnetic induction noise can be removed by electrical circuit processing, and high resolution can be obtained. Furthermore, as described above, the conventional flexible tube is not required, which simplifies the structure and facilitates insertion into the guide tube.

Note that fixing the metal sheaths to each other is not limited to brazing, and adhesives or fixing members may also be used.

As explained above, according to the present invention, an eddy current current meter with little change in electromagnetic induction noise and high measurement resolution can be realized, and is suitable for measuring the flow velocity and flow rate of conductive fluids to be measured such as liquid sodium. suitable.

[Brief explanation of the drawing]

Fig. 1 is a configuration explanatory diagram showing an example of the detection unit DET that constitutes the detection section of this type of device, Fig. 2 is an explanatory diagram of the operation of Fig. 1, and Fig. 3 shows an example of the conventional lead wire structure. FIG. 4 is an explanatory diagram showing an example of a lead wire structure according to the present invention. STW...Metal sheath twisted wire, WL...Guide tube.

Claims (1)

[Scope of utility model registration request] Using a detection section that includes an excitation coil to which an alternating current signal is applied along the flow direction of the conductive fluid to be measured and at least two detection coils arranged near the excitation coil, any two detection coils can be used. In an eddy current anemometer configured to determine the flow velocity of a fluid to be measured based on the difference between the output signals of An eddy current current meter characterized by a metal sheath that is fixed to each other.