JP5364896B2 - Differential transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem in conventional differential transformers that probe bodies swing and entire probe bodies collide against a bobbin tube when an external strong impact is applied to the bobbin tube since a space is formed between an inner circumference of the bobbin tube and an entire periphery of guide members in their construction. <P>SOLUTION: In the differential transformer, a first and a second guide members 24, 25 are attached to a front end 22a and a back end 22b of a magnetic core 22, a filler portion 40 filling the space from the inner circumference 12 of the bobbin tube 10 is provided at the periphery of the first and the second guide members 24, 25, thereby deformation of the probe body 20 is controlled in the radial direction B to fix the position of the probe body 20 in the radial direction B. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a differential transformer that detects the amount of linear movement of a detection target, and in particular, fills a gap between an outer peripheral surface of a first and second guide member attached to a probe body with an inner peripheral surface of a bobbin tube. A new part for preventing the probe body from swinging due to an external impact and preventing the probe body from colliding with the bobbin tube by providing a portion and restricting the displacement of the probe body in the radial direction. It is about the improvement.

  Nowadays, accurate measurement of machine quantity is indispensable for control technology in the industrial field, and a differential transformer (LVDT) is an example of a sensor that converts a mechanical stroke into an electric signal. Sensors are often used in harsh environments and require environmental resistance. However, the differential transformer has a structure excellent in environmental resistance including vibration and impact.

  This type of differential transformer that has been conventionally used is also shown in the following non-patent document, but is generally configured as shown in FIGS. 4 is a cross-sectional view of a conventional differential transformer, and FIG. 5 is a front view showing the differential transformer of FIG. In FIG. 4, a well-known detection coil 11 composed of an excitation winding and an output winding is wound around the outer periphery of the bobbin tube 10, and a probe body 20 can be moved forward and backward inside the bobbin tube 10. Has been inserted. The probe body 20 is provided with a nonmagnetic probe portion 21 and a magnetic core 22, and the probe portion 21 and the magnetic core 22 are integrated with each other by a connection portion 23 such as a male screw and a female screw. It is connected. An arbitrary detection target (not shown) is connected to the probe unit 21, and the output voltage of the detection coil 11 is changed with the displacement of the magnetic core 22 along the axial direction A. That is, the linear movement amount of the detection target can be detected based on the change in the output voltage of the detection coil 11.

  A first guide member 24 having an outer diameter larger than the outer diameter of the magnetic core 22 is disposed on the distal end side 22 a of the magnetic core 22. The first guide member 24 is a member coated with a resin such as polytetrafluoroethylene, and extends along the inner peripheral surface 12 of the bobbin tube 10 when the probe body 20 is inclined in the bobbin tube 10. Are slid. That is, the first guide member 24 protects the distal end side 22 a of the magnetic core 22.

Joe Nishiguchi, Shinko Denshi Co., Ltd. “Differential Transformer-Its Performance and Utilization Technology”, April 30, 1971 Shinko Electric Co., Ltd. “Differential Transformer Handbook”

  In the conventional differential transformer as described above, since the gap 30 is formed between the bobbin tube 10 and the inner peripheral surface 12 over the entire outer periphery of the first guide member 24, a strong impact from the outside is generated by the bobbin tube. If it adds to 10, the probe body 20 will shake, and the probe body 20 whole will collide with a bobbin tube. And when the impact by this collision is strong, the characteristic as a sensor may change.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to prevent the probe body from shaking due to an external impact and to prevent the probe body from colliding with the bobbin tube. Is to provide a dynamic transformer.

In the differential transformer according to the present invention, a probe body having a magnetic core is movably inserted into a bobbin tube having a detection coil wound around the outer periphery thereof, and the displacement along the axial direction of the magnetic core. A differential transformer in which the output voltage of the detection coil is changed along with the first and second guide members attached to the probe body and disposed on the front end side and the rear end side of the magnetic core. provided, wherein the outer periphery of the first and second guide members, said fill the gap between the inner peripheral surface of the bobbin tube, and filling unit is provided for regulating the displacement of the probe body according to the radial direction The tip of the first guide member disposed on the tip side of the magnetic core is provided with a tapered taper surface.
In addition, a part of the outer periphery of the first and second guide members is provided with a notch that forms a drain groove between the inner periphery of the bobbin tube.

According to the differential transformer of the present invention, the probe according to the radial direction is provided with a filling portion that fills a gap between the inner peripheral surface of the bobbin tube on the outer periphery of the first and second guide members attached to the probe body. Since the displacement of the body is restricted, even if an impact is applied to the bobbin tube from the outside, the probe body can be prevented from shaking and the probe body can be prevented from colliding with the bobbin tube. Thereby, it is possible to avoid the possibility that the characteristics as a sensor change.
In addition, a part of the outer periphery of the first and second guide members is provided with a notch for forming a drain groove between the inner peripheral surface of the bobbin tube, so that it has entered the bobbin tube. Foreign matter such as moisture and dust can be discharged to the outside. Therefore, the probe body can be prevented from being damaged by the foreign matter, and the displacement of the probe body can be prevented from being disturbed by the foreign matter.

The best mode for carrying out the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
1 is a sectional view of a differential transformer according to a first embodiment of the present invention, and FIG. 2 is a front view showing the differential transformer of FIG. The same or equivalent parts as those of the conventional differential transformer will be described using the same reference numerals. In FIG. 1, a well-known detection coil 11 composed of an excitation winding and an output winding is wound around the outer periphery of a bobbin tube 10, and a probe body 20 can freely advance and retreat inside the bobbin tube 10. Has been inserted. The probe body 20 is provided with a nonmagnetic probe portion 21 and a magnetic core 22, and the probe portion 21 and the magnetic core 22 are integrated with each other by a connection portion 23 such as a male screw and a female screw. It is connected. An arbitrary detection target (not shown) is connected to the probe unit 21, and the output voltage of the detection coil 11 is changed in accordance with the displacement along the axial direction A of the magnetic core 22. That is, the linear movement amount of the detection target can be detected based on the change in the output voltage of the detection coil 11.

  First and second guide members 24 and 25 having outer diameters larger than the outer diameters of the probe portion 21 and the magnetic core 22 are disposed on the front end side 22 a and the rear end side 22 b of the magnetic core 22. ing. The first guide member 24 is screwed to a screw portion (not shown) provided on the distal end side 22 a of the magnetic core 22, and the second guide member 25 is attached to the outer periphery of the probe portion 21. It is fitted into a groove (not shown) provided.

  Here, in the conventional differential transformer, the gap 30 is formed between the inner peripheral surface 12 of the bobbin tube 10 over the entire outer periphery of the guide member 24 (see FIG. 5). The configuration of this embodiment Then, the filling part 40 which fills the said clearance gap 30 is provided in the outer periphery of each guide member 24,25. That is, the outer diameters of the first and second guide members 24 and 25 constituted by the outer end of the filling portion 40 are substantially equal to the inner diameter of the bobbin tube 10. In this example, the inner diameter of the bobbin tube 10 is Whereas the outer diameter of the first guide member 24 is 4.67 mm, the outer diameter of the second guide member 25 is 4.66 mm.

  Further, a notch 42 that forms a drain groove 42 a between the first and second guide members 24 and 25 and the inner peripheral surface 12 of the bobbin tube 10 is provided in a part of the outer periphery of the first and second guide members 24 and 25. In this embodiment, the notches 42 are arranged 180 degrees apart from each other. Further, by providing the notch 42, the filling portion 40 is configured by a pair of protrusions 41 whose outer ends are close to the inner peripheral surface 12.

  Next, the operation of the filling part 40 and the notch 42 will be described. As described above, the filling portion 40 fills the gap 30 and is substantially in contact with the inner peripheral surface 12 of the bobbin tube 10. Thereby, the filling unit 40 restricts the displacement of the probe body 20 in the radial direction B, and fixes the position of the probe body 20 with respect to the bobbin tube 10 in the radial direction B. Therefore, even if an impact is applied to the bobbin tube 10 from the outside, the probe body 20 can be prevented from shaking, and the probe body 20 can be prevented from colliding with the bobbin tube 10. The first and second guide members 24 and 25 are coated with a resin such as polytetrafluoroethylene and are slid along the inner peripheral surface 12 as the probe body 20 is displaced.

  On the other hand, there is a possibility that foreign matters such as moisture and dust enter and accumulate in the bobbin tube 10. In the configuration of this embodiment, a notch 42 is provided in a part of the outer periphery of the first and second guide members 24 and 25, and the drain groove 42 a is formed between the inner peripheral surface 12 of the bobbin tube 10. The foreign matter can be discharged from the drain groove 42a. Therefore, the probe body 20 can be prevented from being damaged by the foreign matter, and the displacement of the probe body 20 can be prevented from being disturbed by the foreign matter.

Embodiment 2. FIG.
FIG. 3 is a front view showing a differential transformer according to the second embodiment of the present invention. The same or equivalent parts as those of the differential transformer of the first embodiment will be described using the same reference numerals. In the first embodiment, it has been described that the filling unit 40 includes a pair of protrusions 41 arranged so as to be shifted from each other by 180 degrees. However, in the second embodiment, the filling unit 40 is shifted from each other by 60 degrees. It is comprised from the three protrusion 41 arrange | positioned. Other configurations are the same as those in the first embodiment.

  As described above, even in the filling portion 40 constituted by the three protrusions 41 arranged so as to be shifted from each other by 60 degrees, as in the configuration of the first embodiment, the probe body 20 can be prevented from shaking and the bobbin of the probe body 20 can be prevented. Collision with the tube 10 can be prevented. That is, the configuration of the filling portion 40 is not limited as long as the gap 30 can be filled and the displacement of the probe body 20 in the radial direction B can be restricted, and the number of the protrusions 41 is arbitrary.

It is sectional drawing of the differential transformer by Embodiment 1 of this invention. It is a front view which shows the differential transformer of FIG. It is a front view which shows the differential transformer by Embodiment 2 of this invention. It is sectional drawing of the conventional differential transformer. FIG. 5 is a front view showing the differential transformer of FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Bobbin tube 11 Detection coil 12 Inner peripheral surface 20 Probe body 22 Magnetic body core 22a Front end side 22b Rear end side 24,25 1st and 2nd guide member 30 Gap 40 Filling part 42 Notch 42a Drain groove A Axial direction B Diameter direction

Claims (2)

A probe body (20) having a magnetic core (22) is movably inserted into a bobbin tube (10) around which a detection coil (11) is wound on the outer periphery. The magnetic core (22) A differential transformer in which the output voltage of the detection coil (11) is changed in accordance with the displacement along the axial direction (A).
First and second guide members (24, 25) attached to the probe body (20) and disposed on the front end side (22a) and the rear end side (22b) of the magnetic core (22).
With
The outer periphery of the first and second guide members (24, 25) is filled with a gap (30) between the inner peripheral surface (12) of the bobbin tube (10) and related to the radial direction (B). A filling portion (40) for restricting displacement of the probe body (20) is provided ;
A tapered surface is provided at the tip of the first guide member (24) disposed on the tip side (22a) of the magnetic core (22).
A differential transformer characterized by that.   A notch that forms a drain groove (42a) between a part of the outer periphery of the first and second guide members (24, 25) and the inner peripheral surface (12) of the bobbin tube (10). The differential transformer according to claim 1, wherein (42) is provided.

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