JPH0132732Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a differential transformer, and particularly to an improved differential transformer that can measure the amount of movement of the core over a wide range.

BACKGROUND ART Conventionally, a differential transformer is well known in which a movably provided core is excited by an excitation coil and the amount of movement of the core is detected based on the output of the differential coil. Since it is possible to measure the amount of movement with high precision, it is widely used as a variety of displacement measuring instruments and for other purposes.

FIG. 1 shows the structure of such a conventional differential transformer, and FIG. 2 shows its electric circuit.

That is, a differential transformer generally includes an excitation coil 10 and a differential coil 12 provided on the fixed side, and a core 14 made of a magnetic material is inserted into the center of both coils so as to be movable in a linear direction. There is.

The excitation coil 10 is always excited with a constant alternating current voltage E. Further, the differential coil 12 is connected to the excitation coil 1 along the moving direction of the core 14.
A pair of first coils 1 spaced apart from each other at both ends of the coil 1.
2a and a second coil 12b, these coils 12a and 12b are
E ₁ and E ₂ are differentially connected as shown in FIG. 2 so that a difference calculation is performed.

With the above configuration, the excitation coil 10
The core 14 is excited with a constant AC voltage E.
When the core 14 moves, the reactance of the first coil 12a and the second coil 12b changes, causing a difference in the induced voltages E ₁ and E ₂ of the two coils 12a and 12b. gives a predetermined output voltage _e1 .

Since this output voltage e ₁ accurately corresponds to the amount of movement of the core 14, it is possible to accurately measure the amount of movement of the core 14 from the output e ₁ of the differential coil 12.

Therefore, when such a differential transformer is used as a displacement measuring device, by connecting the probe and the core 14 with the connecting arm 16, the amount of movement of the probe can be accurately determined as the amount of movement of the core 14. It becomes possible to measure

However, in such a conventional differential transformer,
As shown in FIG. 1, the first and second coils 12a and 12b forming the differential coil 12 are installed apart from each other in the moving direction of the core 14 across the excitation coil 10. There is a drawback that the range in which the reactance of the second coil 12b changes to follow the movement of the core 14 is limited to an extremely narrow range. As a result, the conventional differential transformer has the disadvantage that it cannot accurately measure displacement over a wide range and cannot be used as a displacement measuring device for large strokes.

Purpose of the Invention The present invention was devised in view of such conventional problems, and its purpose is to provide a differential transformer that can accurately measure the amount of displacement over a wide range.

Structure of the Invention In order to achieve the above object, the differential transformer of the present invention is a differential transformer in which a movably provided core is excited by an excitation coil and the amount of movement of the core is detected based on the output of the differential coil. In the transformer, the core is formed in a hollow cylindrical shape, and the one coil is spaced apart from each other inside the core, and the other coil is spaced apart from each other outside the core.

Embodiment Next, a preferred embodiment of the present invention will be described based on the drawings. Incidentally, members corresponding to those of the conventional example shown in FIGS. 1 and 2 are given the same reference numerals, and their explanations will be omitted.

3 and 4 show a preferred embodiment of the differential transformer of the present invention. A core 14 made of a magnetic material is provided so as to be movable relative to each of these coils 10 and 12.

A characteristic feature of the present invention is that the core 14 is formed into a hollow cylindrical shape, and either the excitation coil 10 or the differential coil 12 is arranged at a distance inside the core 14, and the other is arranged at a distance outside the core 10. It's what I did.

In the embodiment, the core 14 is formed into a hollow cylindrical shape, and is fixedly attached to the main body frame 20 by a support base 18 so as to be movable along the cylindrical center axis direction. The support stand 18 supports the core 14
A cylindrical support member 18a with a height l that supports one end side.
and a slide shaft 18b extending from the other end of the cylindrical support member 18a along the central axis of the cylinder, and the slide shaft 18b is attached to a bearing 22 formed in the main body frame 20 along the axial direction. It is pivoted so that it can slide freely.

Therefore, the core 14 can move along the central axis direction of the cylinder, and in the embodiment, the height l of the cylindrical support member 18a that allows the core 14 to move over a wide range is set to be large. are doing.

Further, in the embodiment, the excitation coil 10 is arranged at a distance from the center inside the core 14, and is attached and fixed to the main body frame. put it here,
The excitation coil 10 is fixed to the main body frame by forming at least one arm insertion slit in the cylindrical side surface of the core 14 along the direction of movement thereof.
A support arm may be inserted into the slit, and the excitation coil 10 disposed inside the core may be supported and fixed to the main body frame located outside the core 14. In addition to this, the height l of the cylindrical support member 20 of the support stand 18 is made long, and an arm insertion slit is formed here in the same manner as described above, so that the excitation coil 10 can be attached to the main body frame using the support arm. It is also possible to attach and fix it to.

In order to prevent the arm insertion slit formed in this way from coming into contact with the support arm and preventing movement of the core 14, in the differential transformer of the embodiment, some kind of rotation prevention means is provided on the support base 18. There is.

Further, in the embodiment, the differential coil 12 is arranged concentrically outside the core 14, and is attached and fixed to the main body frame by a support arm (not shown). Here, a first coil 12a and a second coil 12b forming the differential coil 12 are each formed to have a height half that of the excitation coil 10, and these first and second coils 12a, 12b are arranged one on top of the other along the moving direction of the core 14.

Therefore, in the differential transformer of the embodiment, the excitation coil 10 and the differential coil 12 are arranged concentrically at approximately the same height, and each of these coils 10, 12
The core 14 moves along the cylindrical axis direction between them.

As described above, in the differential transformer of the present invention, the core 14 is formed into a hollow cylindrical shape, and one of the excitation coil 10 and the differential coil 12 is disposed inside the core 14, and the other is disposed outside the core 14. Even when the first coil 12a and the second coil 12b forming the differential coil 12 are arranged in an overlapping manner, and the core 14 moves over a wide range, the first and second coils 12
It becomes possible to accurately change the reactances of a and 12b in accordance with the movement of the core 14.
Therefore, it becomes possible to measure the amount of displacement of the core 14 over a wide range from the output e1 of the differential coil 12.

In this way, in the differential transformer of the present invention, the core 14
Since it is possible to accurately measure the amount of displacement over a wide range, it can be widely used, for example, as a long stroke displacement measuring device or for other purposes.

In the above embodiment, the excitation coil 10 is placed inside the core 14 and the differential coil 12 is placed outside the core 14. However, the present invention is not limited to this. 12. A structure may be adopted in which the excitation coil 10 is disposed outside.

Further, in the above embodiment, the core 14 was explained as being formed into a hollow cylindrical shape.
The core 14 may have any other shape as long as it has a hollow cylindrical shape.

Effects of the Invention As explained above, according to the present invention, the first and second coils forming the differential coil can be arranged overlapping each other along the moving direction of the core, so that the amount of movement of the core can be reduced. It becomes possible to measure accurately over a wide range.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a conventional differential transformer, FIG. 2 is an electric circuit diagram of the differential transformer, FIG. 3 is a side sectional view showing a preferred embodiment of the differential transformer according to the present invention, and FIG. This figure is a partially cutaway perspective view of the differential transformer shown in FIG. 3. 10... Excitation coil, 12... Actuation coil, 14...
core.

Claims (1)

[Claims for Utility Model Registration] (1) In a differential transformer in which a movably provided core is excited by an excitation coil and the amount of movement of the core is detected based on the output of the differential coil, the core is hollow. 1. A differential transformer formed in a cylindrical shape, characterized in that one of the coils is spaced apart inside the core, and the other coil is spaced apart outside the core. (2) In the differential transformer described in claim (1) of the utility model registration, the core is formed in a hollow cylindrical shape, and the core, the exciting coil, and the differential coil are arranged concentrically apart from each other. dynamic transformer. (3) In the differential transformer described in either of claims (1) or (2) for utility model registration, at least one arm insertion slit is formed in the core along the direction of movement of the core. 1. A differential transformer characterized in that a coil arranged in a main body frame is attached and fixed to a main body frame by a support arm extending through the arm insertion slit.