JPS6295401A - Position detecting device - Google Patents

Abstract

PURPOSE:To obtain a noncontacting position detecting device which is affect by neither heat nor vibration by bending lines of magnetic force produced by flowing a current through an exciting coil nearby to be detected and then generating induced electromotive force at a detection coil, and thus detecting the position of the body to be detected. CONSTITUTION:Coil couples 1-(n) consisting of exciting coils B and detection coils C arranged above them are arranged above a plate A made of a ferromagnetic material and the body D to be detected which is made of a ferromagnetic material is provided in a right-left movable state above the detection coil C. A rectangular current is flowed to the exciting coils and coil units where the current is flowed are shifted in the order of 1 2 ... (n) at every period of the rectangular wave. The coil unit 6 nearby the object body D generates large electromotive force. When the body to be detected is detected, a constant threshold voltage VTH which has intermediate value of electromotive force different according to whether there is the body to be detected or not is provided and this VTH is compared with electromotive force generated at each detection coil to detect which coil couple the body to be detected is present nearby.

Description

[Detailed description of the invention] [Industrial application field] Book 9'i! iS1 relates to a position detection device that can detect the position of a detected object in a non-contact manner.

[Object of the present invention]

The wood spring 11 realizes a non-contact position detection device that is not affected by heat or vibration, has a simple structure, and is easy to maintain.

[Effect]

The magnetic lines of force generated by passing a current through the excitation coil are bent by the approach of the object to be detected, and an induced electromotive force is generated in the detection coil, thereby detecting the position of the object.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained in detail with reference to an example of a structure shown in the accompanying drawings.

In Fig. 1, a coil pair 1.2.3Φ...n consisting of an excitation coil B and a detection coil C placed above it is located in the northern part of a plate A having an appropriate length and made of a ferromagnetic material. A detection object made of a ferromagnetic material is provided above the detection coil C so as to be movable in the left and right direction.

In the above configuration, the rectangular wave 1rL shown in FIG.
It is assumed that the current is passed to the excitation coil in a fourth order, and the coil unit through which the current flows is sequentially changed from 1→2→3→...→n every cycle of the rectangular wave.

Coil pair where the object to be detected is not nearby (tjS1 Fig. 1, ?,
3.4.5.7...n), the iH force generated in the detection coil is small, and a large electromotive force is generated in the coil pair (6 in Figure 1) where the detected object is nearby, and The voltage generated across the detection coils connected in series is ft.
It will look like Figure 53. FIG. 4 is a horizontal view of the components of the sixth coil pair shown in FIG.
5(a) shows a case where there is no object to be detected on the detection coil C, and FIG. 5(b) shows a case where there is an object to be detected on the detection coil C.

It is assumed that an 'itt current flows in the direction of the arrow in Fig. 4 through the excitation coil B. In Fig. 5, the direction of this current is shown as x when it flows perpendicular to the page from the front to the back, and when it flows from the back to the front. Represent with a fist.

When a current is passed through the excitation coil B in the above direction, magnetic flux is generated in the direction shown in the diagram (a), but the distribution of the magnetic flux generated from the excitation coil B shows that the Gi permeability of the ferromagnetic material is extremely higher than that of air. Because it is large, it is biased towards the bottom (ferromagnetic plate side). However, as shown in the figure, when the object to be detected approaches the top of the detection coil, the object to be detected is a ferromagnetic material with high magnetic permeability. Therefore, the magnetic field line component 111 forms a molecule lJ that spreads upward (toward the coil B side). By the way, according to the law of electromagnetic induction, the electromotive force e generated in the coil is proportional to the time change of the magnetic flux Φ interlinking with the coil, where N is the number of turns of the coil. For this reason, if the current flowing through the excitation coil B is sequentially made to flow in a rectangular wave through each coil pair as shown in FIG. 2, the magnetic flux generated in the detection coil can also be changed over time.

When the electromotive force of the detection coil C is detected by changing the current flowing through the excitation coil B in this way, the number of magnetic fluxes interlinking to the detection coil C of coil pair 6 is greater than the magnetic flux interlinking to the detection coils of other coil pairs. Since there are many, the generated electromotive force also becomes large.

This detection is performed by setting a constant value 1 [voltage VT)l, which has an intermediate value of the electromotive force that differs depending on the presence or absence of the object to be detected, as shown in Figure 3, and comparing the electromotive force generated in this VTR and the detection coil. Accordingly, it is possible to detect which coil pair the object to be detected is currently near.

As a specific method, a method can be considered in which a rectangular waveform applied to an excitation coil is set at a L by a counter or the like, and counting is stopped at the moment the electromotive force of the detection coil exceeds VTH. However, before applying current to the excitation coil of coil pair 1, it is necessary to reset the counter and set the count to O.

With this method, the position of the object to be detected can be detected with a resolution of 1/n.

Also, if the object to be detected exists between coil pairs n and n+1, and an electromotive force exceeding VTH is generated in two or more coil pairs, a counting method such as taking the average value is used! It is also possible to further improve the resolution using IS.

[Effect of final completion lJj]

As described above, according to the present invention, the position of an object can be detected without being affected by heat, vibration, etc., and with a device having a simple structure. Furthermore, since it uses magnetic force, it has the advantage that it can also be used in liquid level meters and flow meters used for polluted liquids.

4 Brief explanation of the drawings IJI Fig. 1 is a diagram showing an embodiment of the position detection base according to the present invention, Fig. 2 is a waveform diagram of the current flowing through the exciting coil, and Fig. 3 is the current induced in the detection coil. Figure 4 is a perspective view of a specific coil pair, Figure 5 (+) is a diagram showing the magnetic flux distribution of the excitation coil when there is no object to be detected, (b)
2 is a diagram showing the magnetic flux distribution of the excitation coil in a state where the object to be detected approaches. FIG.

4th grade

Claims (1)

[Claims] An appropriate number of coil pairs consisting of an excitation coil and a detection coil provided close to this are arranged near a plate made of a ferromagnetic material, and an object to be detected made of a ferromagnetic material is placed near the detection coil. Make it move parallel to the coil on the tangent line of the plate,
A position detection device that detects the position of a detected object by detecting an induced voltage generated in a detection coil when magnetic lines of force generated by passing a current through an excitation coil are bent by the detected object.