JPH03218414A - Electromagnetic flowmeter - Google Patents

Abstract

PURPOSE:To shorten distance between coils and to improve the efficiency of a magnetic circuit by providing the three pairs of coils on the outer periphery of a circular passage while equally dividing the circumference into three parts. CONSTITUTION:On the outer periphery of a pipe P equipped with the circular passage in the internal part while insulating the inner surface, coils C1, C2 and C3 are arranged at the positions dividing the circumference into three parts equally at 120 deg. and one coil is excited so that the magnetic pole is different from those of the other two coils. As shown figures (a), (b) and (c), when an exciting pattern is successively moved in the order of C1, C2 and C3 for the coil equipped with the different magnetic pole from those of the other two coils, a flow rate signal is proportion to the velocity of fluid F and the strength of magnetic flux B is detected from electrode T1, T2 and T3 arranged among the three coils. Thus, the distance between coils is shortened and a magnetic field to be generated to the same exciting current is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method of measuring the flow rate of a fluid flowing in a measuring tube using an electric KAl
The present invention relates to an electromagnetic flowmeter that has a fixed temperature.

[Conventional technology]

A conventional electromagnetic flowmeter of this type has two coils CI and C2 around the outer periphery of a pipe P whose inner surface is insulated, as shown in FIG.
are placed facing each other, and an alternating magnetic field B in the diametrical direction of the pipe P is applied to the fluid F as shown by the arrow to generate a signal voltage eft electrode Tl + ' proportional to the product of the strength of the magnetic field B and the flow velocity of the fluid F.
It is detected by rz.

[Problem to be solved by the invention]

However, in such a coil-type electromagnetic flowmeter configured with K, the distance between the coils C1 and C2 cannot be set to be less than the diameter of the pipe P, so it is necessary to reduce the generated magnetic field. The only options available were to supply a larger current to the coils Cl and Cx or to increase the number of turns in the coils. And coil CI. Supplying a large current to C2 increases the current consumption of the electromagnetic flowmeter, and increasing the number of turns of the coil hinders reduction in weight and size. Furthermore, since the distribution of the weighting function within the K-pipe P is not uniform, there is a problem in that measurement errors occur due to changes in the flow velocity distribution.

[Means to solve the problem]

In order to solve such problems, the present invention has a circular flow path through which fluid flows, and three sets of coils arranged around the outer circumference of this circular flow path, dividing the circumference into three equal parts, and having adjacent coils with opposite polarities. and three electrodes disposed midway between adjacent coils with their pre-leakage in contact with the fluid.

[For production]

In the present invention, the distance between the coils is shortened by arranging all three sets of coils on the outer periphery of the circular flow path by dividing the circumference into three equal parts.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an electromagnetic meter according to an embodiment of the present invention, and the same parts as in the diagram of L-type are given the same reference numerals. In the same figure, a first coil CI
A second coil Cl and a third coil C3 are arranged respectively, and furthermore, at the intermediate point of these mutually adjacent first coil C1 + second coil C2 and third coil C3, the tip part contacts the fluid F. First electrode TI+ second electrode T! +Third electrode T3 is similarly arranged in three equal parts of 120 degrees each.

In such a configuration, 120@l is placed on the outer periphery of the pipe P.
Of the first coil CI, second coil C2 and third coil C1, which are arranged in three equal parts, one coil is excited so that it has a different magnetic pole from the other two coils, and the other The position of the coil with different magnetic poles is shown in Figure 2 (a+ +
tbλ, as shown in (C), the excitation pattern t- is applied in the order of first coil CI + second coil C2 + third coil C3.
Move sequentially. And each first coil C1 l second
The three first coils arranged between the first coil C and the third coil C3
A flow rate signal generated in proportion to the flow velocity of the fluid F and the strength of the magnetic flux B is detected from the electrode TI+the second electrode T2 and the third electrode T3. In addition, by changing the excitation patterns of the coil C2 of the first coil CI+@2 and the third coil C3 as shown in FIGS. can be realized. Furthermore, the fourth
As shown in the figure, the first coil C+, the coil C2 of 1E2
+The excitation current of one set of the third coil C3, for example, the first coil C+, may be doubled (21) with respect to the excitation current i of the coil C3 of the other second coil C2+@3. .

Note that each electrode T+ + samples the above flow rate signal.
There are combinations of Tx + Ts shown by broken lines in FIG. 5 (al to (f)).

According to such purchasing, as shown in FIG. 6(i), the distances between the first coil CI, the second coil C2r, and the third coil C3 are as shown in FIG. 6(b). Since the distance is 3d/2 compared to the conventional distance dlc, the magnetic field generated for the same excitation current becomes large, resulting in a highly efficient magnetic circuit.

[Effects of the Invention] As explained above, according to the present invention, three sets of coils are provided on the outer periphery of a circular flow path through which fluid flows, dividing the circumference into three equal parts, and adjacent coils have opposite polarities. By providing three electrodes whose tips are in contact with the fluid at the midpoints of adjacent coils, the distance between the coils is shortened.
Since the magnetic resistance is reduced and the effectiveness of the magnetic circuit is improved, it is possible to reduce power consumption. Also, by providing three electrodes, the weighting function in the circular flow path is averaged compared to the case of two electrodes, and measurement errors due to changes in flow velocity distribution can be minimized. Excellent effects can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing one embodiment of an electromagnetic flowmeter according to the present invention, FIG. 2 is a diagram showing excitation patterns of each coil, and FIGS. 3 and 4 are diagrams showing other examples of excitation patterns. FIG. 5 is a diagram showing an example of the combination of each electrode for sampling the flow rate signal,
FIG. 6 is a diagram explaining the effect of the present invention, and FIG. 7 is a diagram explaining the effect of the present invention.
FIG. 3 is a diagram showing the configuration of an L magnetic flowmeter. P●●●●Pipe, Cl II1111●First coil, C2 ---Second coil C 3 * @ 1
1●Third coil, T, fist@@@first electrode, 72 m
mmm Second electrode, T3...Third electrode, F...
...Fluid, B...Magnetic flux.

Claims (1)

[Claims] A circular flow path through which fluid flows; three sets of coils arranged on the outer periphery of the circular flow path dividing the circumference into three equal parts, with adjacent coils having opposite polarities; and arranged at a midpoint between the adjacent coils. An electromagnetic flowmeter comprising: three electrodes arranged with their tips in contact with a fluid.