JPS604083Y2 - Position detection device for magnetic moving rod - Google Patents

Description

[Detailed description of the invention] This invention arranges an input winding and a detection winding along the movement path of a magnetic moving rod, and utilizes changes in the degree of magnetic coupling between the two windings to move the rod. The present invention relates to an improvement in a position detection device that indirectly detects the position of a rod.

Figure 1 shows a conventional example of the above-mentioned type of position detection device applied to detect the position of a control rod in a nuclear reactor. The drive shafts (moving rods) 3 and 4 are an input winding and a detection winding, respectively, and are disposed in the pressure vessel 1 so as to cover the entire movement path of the drive shaft 2.

5 is an AC power supply, 6 is an AC/DC conversion circuit, 7 is a military control circuit, and 8
is a position indicator that converts input into position data of the control rod and displays it.

The military control circuit 7 outputs zero voltage when the control rod is at the reference position.

In this configuration, when the drive shaft 2 moves up and down during power control of the reactor, the degree of magnetic coupling between both windings 3 and 4 changes depending on the insertion length of the movement path, so that the total induced voltage in the detection winding 4 is reduced. The voltage changes in accordance with the insertion length, is converted into DC by an AC/DC conversion circuit 6, and is supplied to a position indicator 8 as a position voltage through a military control circuit 7.

However, in this conventional device, the entire movement path insertion part of the drive shaft 2 contributes to the change in position voltage, so when the control rod is pulled up, the nuclear reaction increases, the temperature inside the pressure vessel 1 rises, and the drive shaft When the magnetic permeability of No. 2 changes, there is a drawback that the influence of this temperature drift on the position voltage increases.

This idea was made in order to eliminate the above-mentioned drawbacks of the conventional technology. An intermediate tap is provided in the detection winding, and after the movable rod is inserted into the movement path beyond the intermediate tap position, the intermediate tap is removed. By extracting a voltage and adding it to a predetermined voltage to form a position voltage, the influence of temperature drift in magnetic permeability of the moving rod can be significantly reduced compared to conventional methods. Position detection of a magnetic moving rod. One purpose is to provide equipment.

An embodiment of this invention will be described below with reference to the drawings.

In FIG. 2, 9 is a detection winding, and the intermediate tap 9
1, and the voltage taken out from the terminal 9a is converted to DC by the AC/DC conversion circuit 61, and then sent to the military control circuit 7.
1 to the limiter 101.

The voltage of the intermediate tap 91 is also converted to DC by the AC/DC conversion circuit 62, and then passed through the military control circuit 72 to the limiter 102.
is supplied to

11 is an adder circuit which adds the outputs of the limiters 101 and 102 and sends the result to the position indicator 8.

The limiter 101 uses the output voltage of the military control circuit 71 as a control voltage when the tip of the drive shaft 2 rises in the movement path to the winding position of the intermediate tap 91, and the limiter 102 uses the output voltage of the military control circuit 71 when the tip of the drive shaft 2 rises to the winding position of the intermediate tap 91 as a control voltage. Its output is limited to zero voltage until the winding position of the intermediate tap 91 is exceeded.

The military control circuit 71 has the same function as the military control circuit 7, and the military control circuit 72 makes its output zero voltage when the tip of the drive shaft 2 reaches the winding position of the intermediate tap 91.

In this configuration, the output of the limiter 102 is zero until the drive shaft 2, which is a magnetic material, is inserted into the winding part between the intermediate tap 91 of the detection winding 9 and the terminal 9b. A DC voltage corresponding to the total induced voltage is supplied to the position indicator 8 as a position voltage through the adding circuit 11.

When the drive shaft 2 rises beyond the winding position of the intermediate tap 91, the total induced voltage in the detection winding 9 increases accordingly, but the output of the limiter 101 maintains its limited voltage, and the other The limiter 102 is a middle tap 91 of the detection winding 9.
A DC voltage corresponding to the voltage induced in the winding portion between the terminal 9b and the terminal 9b is outputted, and the DC voltage and the above-mentioned limit voltage are added by an adding circuit 11 and supplied to the position indicator 8 as a position voltage.

In this case, the output of the limiter 102 is affected by the magnetic permeability temperature drift of the drive shaft 2, but the output of the limiter 101 is not affected, so the temperature drift of the position voltage due to the magnetic permeability temperature drift is small.

In the above embodiment, the number of intermediate taps is one, but if necessary, a plurality of intermediate taps may be used, and in the same manner, the voltages of each intermediate tap are sequentially added to form the position voltage.

As described above, according to this invention, the detection winding is provided with an intermediate tap, and until the moving rod, which is a magnetic material, is inserted into the movement path beyond the winding position of the intermediate tap, the entire detection winding is The position is detected using the position voltage corresponding to the induced voltage, and after the winding position of the intermediate tap is exceeded, the position voltage is fixed at a predetermined value, and the position is determined by adding the voltage corresponding to the voltage of the intermediate tap to this. By adopting a configuration in which position detection is performed using voltage, even if the insertion length of the movement path of the moving rod becomes large, the part that contributes to the change in position voltage is not the entire insertion part but a part of it, which is different from conventional methods. The influence of temperature drift on the magnetic permeability of the moving rod can be greatly reduced, and the position detection accuracy can be improved.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional moving rod position detection device;
The figure is a circuit diagram showing an embodiment of a position detecting device for a magnetic movable rod according to this invention. In the figure, 2... a moving rod having magnetism, 3
...Input winding, 8...Position indicator, 9
...Detection winding, 11... Addition circuit, 6
1.62...AC/DC conversion circuit, 71.72...
... Military circuit, 91 ... Intermediate tap, 101
,102...Limiter. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] In a device for detecting the position of the movable rod by disposing an input winding and a detection winding along a moving path of a magnetic movable rod and detecting changes in induced voltage in the detection winding, the detection winding The line is equipped with a center tap, and until the length of the moving rod inserted into the moving path reaches a predetermined length, the total induced voltage of the detection winding is converted into a position voltage by direct current conversion, and after reaching the predetermined length, A position detecting device for a movable rod having magnetism, characterized in that the position voltage is fixed and the voltage of the intermediate tap is converted into DC and added to the position voltage to obtain the position voltage.