JPS59105516A - Differential transformer - Google Patents

Abstract

PURPOSE:To achieve a high accuracy with light and small construction by arranging a mobile body equipped with a short ring for suppressing mutual induction between first and second coils. CONSTITUTION:A mobile body 41 with a short ring 7 for suppressing mutual induction is inserted into first and second coils 2 and 3 each with an air core. The ring 7 made of material high in the electric conductivity is formed in a ring. An induced elctromotive voltages of the coils 2 and 3 are turned to small voltages E2'' and E3'' suppressed in the level according to the shield space occupancy of the ring 7 and differential voltages E2'' and -E3'' generated associated with a displacement of the mobile body 41. This can improve the accuracy along with a light weight and a small size while falicitating the working and production.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a differential transformer, which is a type of so-called displacement-d voltage converter that converts mechanical displacement into a change in voltage.

Differential transformers are superior to other displacement-voltage converters in terms of accuracy, stability, linearity, training/manufacturing, handling, etc.
This type of converter is currently most commonly used. An example of a conventional differential transformer is the one shown in FIG. 1 is a primary coil, 2 and 6 are secondary coils, and 40 is a movable body including a core portion 4 of high magnetic permeability, such as mild steel, which can move forward and backward along the object 5 to be measured. That is, this 1
When the secondary coil 1 is excited with a constant AC voltage, the secondary coil 2
．． Mutual induced voltages E21 and E3 are induced in 6, respectively, and oJ
The magnetic flux interlinking with each of the secondary coils 2 and 3 changes depending on the displacement of the moving body 40, specifically, the displacement of the core portion 4 with high magnetic permeability, and (change in mutual inductivity), E2 +
This utilizes the fact that E changes, and by differentially connecting the secondary coils 2 and 6, E2- is output from the output end 6.
E is taken out as the displacement output voltage. Usually, this output is processed by rectification, amplification, etc. to make a meter swing, or is used as feedback information for automatic control.

However, although such conventional differential transformers provide sufficiently good performance as described above for general measurements and feedback information for automatic control, they require extremely sophisticated processing when attempting to perform ultra-high precision measurements. It required a great deal of precision, and the responsibility and size were both modest, and the price was also very high.

In view of these circumstances, this invention focuses on the principle of the differential transformer itself, and has developed a differential transformer that achieves the performance that could previously only be achieved with high-end products at a popular price, and has sufficient durability. In addition, in view of the fact that differential transformers capable of ultra-high precision measurement have a narrow measurement range, the present invention also aims to provide a differential transformer with a wider measurement range.

Hereinafter, this invention will be explained based on the drawings. First, the principle of the differential transformer according to the present invention will be explained.

Figure 2 B) is 2 in the longitudinal direction +X) of the primary coil 1.
This is an excerpt of the coil portion of a differential transformer in which the next coils 2 and 6 are equally divided and wound. The primary and secondary coils 1, 2.3 are the same as before. In such an air-core coil state, the secondary coils 2 and 6 each have a mutually induced electromotive force B/2. B/, occurs. Therefore, if the same-phase terminals of the two secondary coils 2 and 6 are differentially connected, they will be in an anti-phase connection state, and no voltage will be generated at the output terminal B due to the canceling effect. The conventional principle is to insert a movable body 40 equipped with a core portion 4 of high magnetic permeability that increases mutual inductivity into the air-core primary coil 1 and secondary coils 2 and 3 shown in FIG. 2 (A). This is to obtain the differential voltage generated as the movable body 40 is displaced (FIG. 1).

In contrast, in the present invention, as shown in FIG. 2(B), a short ring 7 for suppressing mutual induction is installed in the air-core primary coil 1 and secondary coil 2.6 in FIG. 2(A). A movable body 41 provided therein is inserted.

This short ring 7 is made of a high electrical conductivity material (for example, copper) and is formed into a ring shape.

When a high electrical conductivity material is formed into a ring shape in this way, it is between the primary coil 1 and the secondary coils 2 and 6 that it has a characteristic that contributes to suppressing mutual induction. This is understood to be because most of the magnetic flux in the area occupied by the effective length l is consumed by the induced power within the short ring 7. Therefore, the secondary coil 2. The induced electromotive force of B is small voltage B//2 which is suppressed by an amount corresponding to the shielding space occupancy rate of IJ ring 7. B//, becomes.

The basic principle of the differential transformer of the present invention is to obtain the differential voltages B//, B//, which are generated as a result of the displacement of the movable body 41 provided with the short ring 7. That is,
This invention is based on the basic principle of the magnetic anticoupling effect, which is completely opposite to the mutual inductive coupling effect between the primary coil 1 and the secondary coils 2 and 6, which is the basic principle of conventional differential transformers. It is something that can be said.

FIG. 6 shows an embodiment of the present invention, and based on this principle, the ring outer diameter D7 of the short ring 7 is set at a portion 41' of the movable body 41 other than the short ring 7.
In other words, the short ring 7 is formed smaller than D41. In other words, the short ring 7 can be formed by wrapping a copper wire around the movable body 41, by gluing a strip, by gluing a thin plate, or by partial plating. Various methods can be considered, such as attaching a high electrical conductivity material to the movable body 41, but if the ring outer diameter D7 of the short ring 7 is
1' outer diameter D41, the short ring 7
are easily scratched, and these scratches may deteriorate measurement accuracy.

Therefore, the outer diameter of the short ring 7 is determined by the movable body 4.
Outer diameter D41 of part 41' other than short ring 7 of No. 1
It should be made smaller. It has been confirmed through experiments that by doing this, the short ring 7 becomes extremely resistant to scratches, and that doing so does not have any adverse effect on measurement accuracy.

FIGS. 4B) and 4B show a second embodiment of the present invention.

FIG. 4(A) shows a movable body 42 having high magnetic permeability arranged inside and outside the effective length of the air-core primary coil 1 and secondary coils 2, 6 of FIG. 2(A). In this case, the voltage induced in both the secondary coils 2 and 6 is a multiple kB' corresponding to the relative magnetic permeability k of the high magnetic permeability material, compared to the case of the air core shown in Figure 2 B).
, kE',. In this embodiment, the entire movable body 42 is made of a high magnetic permeability material and is provided with the short ring 7 (Fig. 4 (b)).
More accurate differential voltage B/
//, B /// can be obtained.

In addition, here, ``Make the entire movable body 42 a high magnetic permeability material'' means ``Even if the movable body 42 moves to the maximum, it still remains inside or outside the effective length of the primary and secondary coils 1.2.3. "A configuration in which a high magnetic permeability material is disposed throughout." Further, the method of forming the short ring 7 is the same as that in the first embodiment, so a description of backward tilting will be omitted.

FIG. 5 shows a third embodiment of the invention. This embodiment is based on the second embodiment shown in FIG. 4(b), and the short ring 7 is 21i! Divided into 5 short ring pieces 7a
, 7b, and are arranged at a predetermined interval d. Specifically, they are positioned near both ends of the primary coil 1 and secondary coils 2 and 6. The short ring pieces 7a, 7b on both sides naturally move up and down in conjunction with the movable body 42. This prevents nonlinearity near both ends A of the differential transformer, and further expands the linearity maintenance range of the second embodiment with the same coil length, short ring total length, and core length. can do.

As explained above, according to the present invention, since the above-mentioned immediate configuration is adopted, it is possible to develop the operating principle of the differential transformer itself, so to speak, and achieve a one-digit accuracy that could only be achieved with ultra-high-end products. Tests have confirmed that the revolutionary effect can be achieved at a widespread price of , or even lower. Furthermore, it has been confirmed that the differential transformer according to the present invention is extremely lightweight and compact, and is easier to process and manufacture than conventional transformers that have achieved the same level of accuracy. Furthermore, since the outer diameter of the short ring is made smaller than the outer diameter of the parts of the movable body other than the short ring, the short ring is less likely to be damaged and high precision can be maintained over a long period of time. It will be done.

As shown in the example, if the entire movable body is made of a high magnetic permeability material and a short ring is provided there, the accuracy can be further improved, and the short ring can be divided into several short ring pieces. However, if they are arranged at predetermined intervals, the range of linearity maintenance can be further expanded.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing an example of a conventional differential transformer, and Figures 2 (a) and (b) are explanatory diagrams showing the principle of this invention.
(A) shows an empty core state, (B) shows a state in which the movable body is equipped with a short ring, FIG. 6 is an explanatory diagram showing the first embodiment of the present invention, and FIG. (a) and (b) are explanatory diagrams showing a second embodiment of the present invention, in which (a) shows one doctor, two doctors
Next, a high magnetic permeability OT moving body is arranged inside and outside the coil, (b) shows the high magnetic permeability OT moving body equipped with an IJ ring, and Figure 5 shows this. It is an explanatory view showing a sixth example of the invention. 1... Primary coil 2.6 Secondary coil 40.41.42...Movable body 41 (show of movable body) Parts other than IJ ring 7... Short ring d... Between short rings predetermined interval 78
．． 7b Split short ring piece D7 ・
・Short ring ring diameter D41
Outer diameter of parts of the movable body other than the short ring - ~ Amended Procedural Amendment (Voluntary) 1. Display of the case 1982 Patent Application No. 214619 2, Name of the invention Differential transformer 3, Person making the amendment Relationship to the case Patent applicant name Chubu Sanbu (1 person) 4, Name of agent (6720) ) Patent Attorney Takatsuki 1 Meng 5, drawings subject to amendment 6, ? ili positive contents 7, catalog drawing of attached documents 1 copy

Claims (3)

[Claims] (1) A short ring for suppressing mutual induction made of a high conductivity material formed into a ring shape is provided between the primary coil connected to an AC power supply and the differentially connected secondary coil. In addition to arranging the movable body, the outer diameter of the short ring is made smaller than the outer diameter of the movable body (other than the IJ ring), and an output voltage corresponding to the displacement of the movable body is applied from the secondary coil side. A differential transformer characterized by obtaining. (2) The differential transformer according to claim 1, wherein the movable body is entirely formed of a high magnetic permeability material. (3) The differential transformer according to claim 1 or 2, comprising an IJ song and hard split short ring pieces arranged at predetermined intervals.