JPH0624732Y2 - Differential transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a differential transformer that detects a mechanical displacement amount as an electrical signal proportional thereto.

[Conventional technology]

As shown in FIG. 4, the differential transformer comprises a primary coil 12, two secondary coils 14 and 16, and a movable core 18. The primary coil 12 and the secondary coils 14 and 16 are wound around a bobbin made of an insulating material such as bakelite or ebonite (not shown in FIG. 4), and the secondary coils 14 and 16 are arranged in series in the axial direction of the bobbin. Is located in. And the primary coil
12 is connected to an alternating current excitation power source 20. Further, the secondary coils 14 and 16 are connected to the differential amplifier 22, and the secondary voltages V ₁ and V ₂ induced by the current flowing through the primary coil 12 are input to the differential amplifier 22. The differential amplifier 22 outputs an output voltage V ₀ proportional to the difference between the input secondary voltages V ₁ and V ₂ .

On the other hand, the movable core 18 is made of a magnetic material such as soft iron, permalloy, ferrite, etc., and a differential rod 23 made of a non-magnetic material such as stainless steel is connected to the ends. The movable core 18 is inserted into the bobbin, moves in the axial direction in the bobbin as indicated by an arrow 24 in accordance with the mechanical displacement transmitted by the differential rod 23, and is generated in the secondary coils 14 and 16. The secondary voltages V ₁ and V ₂ are changed. Then, the proportional relationship shown by the solid line 26 in FIG. 5 is established between the displacement amount x of the movable core 18 and the output voltage V ₀ . Therefore, the mechanical displacement amount can be obtained by detecting the output voltage V ₀ .

[Problems to be solved by the invention]

However, conventional differential transformers have different output characteristics due to structural dimensional accuracy and variations in materials. Therefore, even if the moving amount of the movable core 18 is constant, the output voltage V ₀ of each differential transformer 10 is within a certain range ΔV ₀ as shown by the alternate long and short dash lines 28 and 30 in FIG.
Shows different values. As a result, the output voltage V ₀
However, even if the voltage is accurately detected, the mechanical displacement cannot be accurately measured due to the difference in the output characteristic (output voltage characteristic) of each differential transformer. Therefore, it is necessary to adjust the output characteristics of the differential transformer, and the following three methods can be considered in order to adjust the electrical characteristics.

Adjust the number of coil turns.

Change the permeability of the core.

Change the length of the core.

However, none of these adjustment methods is easy and adjustment may not be possible.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and an object thereof is to provide a differential transformer capable of easily adjusting output characteristics.

[Means for solving problems]

The present invention has been made by the inventors as a result of various studies to improve the above-mentioned drawbacks of the differential transformer, and as a result, the output characteristics can be changed by changing the distance between the coils of the differential transformer. A bobbin, a primary coil axially arranged on the bobbin, at least one secondary coil coaxially arranged on the bobbin with the primary coil, and at least one of the primary coil and the secondary coil. And a moving means for moving the two in the axial direction by screw coupling.

[Action]

As shown in FIG. 2 (A), the length of the two coils 40 and 42 is 1, and the length of the movable core 44 is L.
When the distance between them is d, each coil 40, 42 and movable core 44
It is assumed that the length of the overlapping portion with and is w. When the distance between the coils 40 and 42 is increased by 2Δd ₁ as shown in FIG. 2B, the length of the overlapping portion between the coils 40 and 42 and the movable core 44 is decreased by Δd _1. And w-Δd ₁ . In addition, the distance between both coils 40 and 42 is further increased, and d + 2
When Δd ₂ (however, Δd ₂ > Δd ₁ ), each coil is
The overlapping portion of the movable cores 40 and 42 becomes w-Δd ₂ and becomes smaller. Therefore, as the distance between the coils 40 and 42 increases, the overlapping portion between the coils 40 and 42 and the movable core 44 decreases, and the influence on the induced electromotive force of the coils 40 and 42 of the movable core 44 decreases. As a result, coil 4
As the distance d between 0 and 42 increases, the output voltage V _{0 with} respect to the moving amount of the movable core 44 changes from the state shown by the solid line in FIG. 3 to the broken line side, and as the distance d decreases, it moves toward the alternate long and short dash line side. Change. That is, the inclination angle θ of the output voltage decreases as the coil interval d increases, and the inclination angle θ increases as the interval d decreases and the output voltage characteristic changes.

Therefore, by moving the movable coil of the present invention in the axial direction of the bobbin, the distance between the coils can be changed and the output characteristics of the differential transformer can be easily adjusted.

〔Example〕

A preferred embodiment of the differential transformer according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a sectional view of a differential transformer according to an embodiment of the present invention.

In FIG. 1, the movable core connecting the operating rods 46 is 44
The bobbin 48 into which the
The winding part 50 is integrally formed on the side. The coil 40 is wound around the winding portion 50. The coil 42 is wound around a winding portion 54 provided on one side of the auxiliary bobbin 52 in the axial direction.

Like the bobbin 48, the auxiliary bobbin 52 is made of an insulating material such as bakelite or ebonite, and the bobbin 48 is inserted into the center hole 56 so as to be movable in the axial direction. Further, a male screw portion (moving means) 58 is provided on the outer peripheral surface of the end portion of the auxiliary bobbin 52 opposite to the winding portion 54. The male screw portion 58 is formed by the coils 40, 42.
It is screwed with a female screw portion (moving means) 62 formed on the inner peripheral surface of the magnetic shield pipe 60 arranged so as to cover the outer peripheral surface thereof.
Each of the coils 40 and 42 is composed of a primary coil and a secondary coil which are arranged in series or in layers.

In the embodiment configured as described above, when the auxiliary bobbin 52 is rotated as shown by the arrow 64 or the arrow 66, the auxiliary bobbin is rotated.
52 moves in the axial direction of the bobbin 48 as shown by the arrow 68.
Then, the coil 42 as a secondary coil wound around the auxiliary bobbin 52 moves in the axial direction of the bobbin 48 integrally with the auxiliary bobbin 52, and the coil interval d changes. Therefore, the auxiliary bobbin 52
By rotating the, the coil spacing d can be changed to easily adjust the output characteristics, and it is possible to eliminate variations in the output characteristics among the differential transformers. Moreover, in this embodiment, the auxiliary bobbin 52 and the magnetic shield pipe 60 are used.
Since and are screw-coupled, delicate adjustment of output characteristics can be accurately performed.

In addition, in the above-mentioned embodiment, the case where the auxiliary bobbin 52 and the magnetic shield pipe 60 are screwed together has been described, but the auxiliary bobbin 52 and the bobbin 48 may be screwed together. Further, the auxiliary bobbin 52 is only required to be able to move in the axial direction with respect to the bobbin 48, and is simply fitted onto the bobbin 48 without being screwed, and after adjusting the output characteristics, by an appropriate means such as an adhesive. The auxiliary bobbin 52 may be fixed to the bobbin 48. Further, in the above embodiment, the case where only the coil 42 as the secondary coil is movable has been described, but both the coils 40 and 42 as the primary and secondary coils may be movable. In the above embodiment, the number of coils is two.
I explained a two-stage differential transformer consisting of two
It can also be applied to a three-stage type differential transformer in which a primary coil and a secondary coil are separately formed.

[Effect of device]

As described above, according to the present invention, at least one of the primary coil and at least one secondary coil can be moved in the axial direction of the bobbin by the moving means, so that the interval between the coils is changed and the output is performed. The characteristics can be adjusted easily.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a differential transformer according to the present invention,
FIG. 2 is a diagram explaining the principle of adjusting the output characteristics of the differential transformer according to the present invention, FIG. 3 is a characteristic diagram showing the relationship between the coil spacing and the output voltage, and FIG. 4 is an explanation of the operation of the conventional differential transformer. FIG. 5 and FIG. 5 are explanatory diagrams of conventional differential and output characteristics. 40, 42 …… Coil, 44 …… Movable core, 48 …… Bobbin, 52
…… Auxiliary bobbin.

Claims (1)

[Scope of utility model registration request] 1. A bobbin, a primary coil axially arranged on the bobbin, at least one secondary coil coaxially arranged on the bobbin with the primary coil, and a primary coil or a secondary coil. And a moving means for moving at least one of the two in the axial direction by screw coupling.