JPS6053448B2 - differential transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a differential transformer that can accurately measure large displacements.

Conventional differential transformers are shown in Figure 1 (3-stage type) or 2-stage type.
The configuration shown in the figure (two-stage type) is adopted, and its equivalent circuit is as shown in FIG.

That is, the two secondary windings 2a and 2b are placed between the primary winding 1 (Fig. 1) or inside the primary winding 1 (Fig. 2).
Displacement is measured by using the difference in electromotive force induced in the secondary windings 2a and 2b, which are arranged in a differential relationship with each other, depending on the position of the iron core 3 arranged in the middle. It is. By the way, such a conventional example is suitable for measuring minute displacements, but is not suitable for measuring large displacements.

That is, since the iron core 3 moves in response to the displacement, the magnetic flux distribution to the primary winding 1 shifts as shown in FIG. There is no longer a linear relationship between the intersecting magnetic flux and displacement, and correct output cannot be obtained.

Therefore, precision measurement is required in a minute area of the iron core, and precision measurement of large displacements is impossible. The present invention was made in order to solve the problems of the conventional art, and an object of the present invention is to provide a differential transformer that can accurately measure large displacements.

In order to achieve this objective, the present invention generates two magnetic fields with different polarities by differentially connecting two windings having the same number of windings and coaxially symmetrically arranging them. 1
The secondary winding is arranged coaxially with the primary winding and overlapped so that the position can be changed symmetrically in the axial direction, and the positional relationship with the primary winding can be changed relatively. and a secondary winding that generates an output according to the number of overlapping turns with each winding of the primary winding that changes by The relative position between the winding and the secondary winding is detected by the output induced in the secondary winding.

More specifically, the present invention winds the primary winding differentially, instead of making the secondary winding a differential winding as in the past, and passes current to the primary winding. The relative position or displacement of the primary winding and the secondary winding is detected by the output induced in the non-differential secondary winding.

The relative positions of the primary and secondary windings correspond to the "equivalent winding" of the secondary winding.

The "equivalent number of turns" refers to the secondary windings 52a that exist on the left and right sides of the axis of symmetry XX'' of the differential primary winding 51, as shown in FIG.
, 52b0, if the windings are A and B, respectively (A-B)
It is expressed as If there is no displacement as shown in FIG. 5a, then the output signal becomes A-B=0.

When a deviation d occurs in Bf)L in FIG. 5, the output signal becomes A-B>0, and the displacement d is detected.

That is, the secondary winding of the present invention operates so that the winding changes in response to displacement (like a variable winding coil). Also,
The differential primary winding 51 generates a symmetrical magnetic flux, as shown in FIG.
Even if a displacement d occurs as shown in FIG. The output of line 52 varies linearly in the case of FIG. 5 up to a displacement corresponding to the length of the secondary winding, and can be precisely measured up to large displacements. Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 6a shows an air-core structure in which two primary windings 61a and 61B having the same number of windings are coaxially arranged symmetrically on the left and right through a separator 63, and the secondary winding 62 is connected to the primary winding 61a. , 61b so that the center of the secondary winding 62 substantially coincides with the axis of symmetry of the primary windings 61a, 61b.

That is, the secondary winding is arranged coaxially with the primary winding and changes its position symmetrically in the axial direction. The windings are arranged in a superimposed manner so that the windings are overlapped with each other, and are configured to produce an output according to the number of turns of the primary winding that overlaps with each winding, which changes as the positional relationship with the primary winding changes relative to the primary winding. has been done.
Since the magnetic path resistance is high, the magnetic flux does not become 0, and it is possible to accurately measure the large displacement caused by the displacement of the magnetic flux of the differential primary winding consisting of the two primary winding I wires 61a and 61b. Note that the length 1 of the separator 63 may be approximately 0, or may be several to several 10D. FIG. 6b shows a configuration in which the secondary windings are two secondary windings 62a and 62b separated by a predetermined length and connected non-differentially.

In this case, the distance between the primary windings 61a and 61b is also set according to the interval between the secondary windings 62a and 62b. FIG. 7 shows an embodiment of the present invention in which a magnetic core (eg, iron core, ferrite, etc.) is used instead of an air core structure. In FIG. 7, the primary winding 71a is fixedly wound around the magnetic core 14a,
The primary winding 71a is fixedly wound around the magnetic core 74b.
4a and 74b are coupled by a non-magnetic material 75. 2
The secondary winding 72 is disposed coaxially outside the primary windings 71a, 71b, and the center of the secondary winding 72 is located between the primary windings 71a, 71b.
1b is configured to substantially coincide with the axis of symmetry of 1b.

Even if the differential primary winding is fixedly wound around the magnetic core in this way,
The magnetic flux of the primary winding does not change due to displacement, and large displacements can be measured with high accuracy. FIG. 8 shows the secondary winding 82
is provided inside the primary windings 81a and 81b, and has an air-core structure. Similar to the one in FIG. 6, the two primary windings 81a and 81b are coupled by a separator 83, and the center of the secondary winding 82 substantially coincides with the axis of symmetry of the primary windings 81a and 81b. Even in this case, large displacements can be measured with high accuracy. FIG. 9 shows a semicircular version of the embodiment shown in FIG. 6, in which the secondary winding 92 is disposed outside the primary windings 91a and 91b, and the center of the secondary winding 92 is arranged in a semicircular manner. Winding wire 91a,
The primary windings 91a and 91b are connected by a separator 93, which is similar to that shown in FIG.

Even with this configuration, similar effects can be obtained. Figure 10 shows
This is a circular version of the embodiment shown in FIG. Primary winding 10
1a and 101b are fixedly wound around magnetic cores 104a and 104b, respectively, and made of non-magnetic material (for example, ceramic, resin, etc.)
They are symmetrically connected via 105.

Nonmagnetic material 105 is inserted to increase magnetic resistance. A separator 103 is provided at the connection point between the primary windings 101a and 101b, but this may be omitted. The secondary winding 102 is arranged so that its center coincides with the axis of symmetry of the primary windings 101a, 101b.

A feedback core 106 is provided inside the primary windings 101a and 101b in order to lower the magnetic resistance of the feedback magnetic path. Even with this configuration, similar effects can be obtained. Note that the feedback core may be omitted. As is clear from the above description, the differential transformer according to the present invention has two windings having the same number of windings differentially connected, and two windings having different polarities arranged coaxially so as to be symmetrical. A primary winding that generates two magnetic fields, and a primary winding that generates two magnetic fields.
The primary winding is arranged coaxially with the secondary winding and is arranged so as to be overlapped so that it can change its position symmetrically in the axial direction, and changes as the positional relationship with the primary winding changes relatively. Produces an output according to the number of overlapping turns with each winding of the winding 2
The primary winding generates two magnetic fields with different polarities, and the relative position of the primary winding and the secondary winding related to displacement is determined by the output induced in the secondary winding. Since the magnetic flux of the differential primary winding does not change due to displacement, large displacements can be measured with high accuracy.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing a conventional differential transformer,
3 is a circuit diagram showing an equivalent circuit of the differential transformer shown in FIG. 2, FIG. 4 is an explanatory diagram showing the operation of the conventional example, FIG. 5 is an explanatory diagram showing the principle of the present invention, 7, FIG. 8, FIG. 9, and FIG. 10 are cross-sectional views showing embodiments of the present invention. 1, 11...Primary winding, 2a, 2b, 12a,
12b... Secondary winding, 3, 13... Iron core, 51a, 51b, 61a, 61b, 71a, 71b
, 81a, 81b, 91a, 91b, 101a, 101
b, 111a, 111b...Primary winding, 52,6
2, 72, 82, 92, 102, 112, 122...
・・・Secondary winding, 63, 83, 93, 103, 113・
...Separator, 74a, 74b, 104a, 10
4b, 114a, 114b...Magnetic core, 75,1
05...Nonmagnetic material.

Claims (1)

[Claims] 1. A primary winding in which two windings with the same number of windings are connected differentially and coaxially arranged symmetrically to generate two magnetic fields with different polarities, and this primary winding. The primary winding is arranged coaxially with the primary winding and is arranged in a superimposed manner so that the position can be changed symmetrically in the axial direction, and changes as the positional relationship with the primary winding changes relative to the A differential transformer comprising a secondary winding that produces an output according to the number of overlapping turns with each winding.