JPH0431540B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a displacement detector having a coil and a diaphragm, and more particularly to the mounting position of a spring that regulates pressure.

[Conventional technology]

Currently, there are many examples of using displacement detectors equipped with coils and diaphragms to control electronic devices, etc., but most of them show the operating principle and the component structure, such as the conventional example ``Japanese Patent Application Laid-Open No. 17656/1982''. There are very few concrete descriptions of it.

The present invention has been made in view of this point, and at the same time specifies the overall component structure and provides for the attachment of a spring that resists the buoyant force of the diaphragm.

[Problem that the invention seeks to solve]

The more iron moves within the coil, and the greater the sliding stroke, the greater the reactance change of the coil, and the easier the subsequent discrimination process becomes. If the size of the magnetic body and the stroke are limited due to the overall size, it is difficult to increase the reactance change of the coil.

[Means for solving problems]

The present invention attempts to increase the change in the reactance of the coil by providing a push spring that resists the buoyancy of the diaphragm on the inner diameter of the magnetic body that slides inside the coil. In other words, the reactance changes even when only the magnetic material slides inside the coil, but since the compression spring provided on the inner diameter continues in proportion to the rise of the magnetic material, the wire gradually becomes denser within the coil. . This causes the iron content to gradually increase within the coil, increasing the reactance of the coil proportionally.

[Effect]

The reactance change created by the magnetic material alone,
The reactance change created by the change in the iron content of the push spring is extracted in a combined form, and the change becomes large.

[Embodiment of the Invention] An embodiment of the present invention is shown in FIGS. 1, 2, 3,
This will be explained with reference to FIGS. 4, 5, and 6.

1 is a rigid base molded from ABC resin or polyacetal resin, and has a cylindrical part 2 having a fitting protrusion at the center of the outside, and primary coils 7 and 2 in which a polyurethane-coated electric wire or the like is wound around the cylindrical part 2. A bobbin 6, which is a rigid body made of ABS resin or polyacetal resin and has a next coil 8, is removably inserted and fixed by the fitting protrusion 3. The bobbin 6 has a winding drum outer diameter of ψ17 on both the primary and secondary sides.
It is wound 2200 times (resistance value 630 to 650Ω), the secondary coil 8 is placed closer to the magnetic material, and the primary coil 7 is placed outside and inserted and fixed, and the frequency 50 is applied to the primary coil.
~70KHz square wave DC current is applied. The magnetic body 17 is attached so as to slide inside the secondary coil 8. Further, inside the base 1, there is a thin film diaphragm 9 having a pressure receiving surface 10 and a base part 19 formed of rubber or cloth-filled rubber, a disc body 12 that comes into contact with the pressure receiving surface 10, and a screw perpendicular to the diaphragm 9. A rigid sliding body 11 is provided, which is made of a polyacetal resin containing oil or paraffin, and has a hollow shaft 13, a circumferential wall with a fitting protrusion, and a circumferential groove 15. The buoyant force of the diaphragm 9 is uniformly received on each surface of the diaphragm 9 so that the hollow shaft portion 13 is always held perpendicular to the center portion, and the bearing port 4 is slid. An adjusting screw 20 made of a rigid body made of polyacetal resin is in contact with the hollow shaft portion 13 of the sliding body 11 at one end, and by turning the adjusting screw 20, the slider 11 and the magnetic body 1
7 is engaged so that fine adjustments can be made up and down. Further, the circumferential wall portion 14 is provided with grooves 25 and guide protrusions 26 so that a magnetic body 17 made of a circular steel plate made of permalloy or ferromagnetic material can be positioned in a fixed direction.
and are removably inserted and fixed by a fitting protrusion 16. Further, in the circumferential groove portion 15, a push spring 18 that adjusts the amount of movement of the sliding body 11 against the buoyancy of the diaphragm 9 biases the sliding body 11 based on the inner surface around the bearing port 4 of the base 1, and It is located inside the body 17 and is attached so that it can expand and contract at the inner circumference of the differential transformer 5 at all times.

A rigid upper lid 21 made of ABS resin or polyacetal resin is welded and fixed to the base 1 in such a way as to form an air chamber 29 between it and the diaphragm 9,
It has a pressure receiving port 22 in the center of the surface that connects a pressure transmission tube 24 led from a washing tub of a washing machine, etc.
Further, a fixing protrusion 23 for preventing the diaphragm 9 from deflecting is provided near the inner surface pressure receiving port 22.

The protective frame 27 is detachably inserted and fixed between the fitting protrusion 28 and the end face of the bobbin 6 so as to cover the differential transformer 5 to prevent dust and water droplets.

FIG. 7 shows the installation of the differential transformer 5, and will be introduced as the same example as above. The basic configuration is base 1
A cylindrical part 2a is provided at the center of the outside of a, and this cylindrical part 2
A differential transformer 5 is removably inserted into and fixed to a.

Next, the operation will be explained.

When a 5V square wave DC power supply with a frequency of 50 to 70KHz is applied to the primary coil 7 of the differential transformer 5 through the drive circuit shown in Figure 5, the initial induced voltage generated in the secondary coil 8 is approximately 0.2V. It is. Pressure receiving port 22
When air is injected from the diaphragm 9 pressure receiving surface 1
0 floats up and pushes up each surface of the disc body 11 uniformly against the push spring 18. Therefore, the magnetic body 17 slides from the outside to the inside of the end face of the output side, that is, the secondary coil 8, while maintaining a uniform gap with the inner circumference of the differential transformer 5 without being oblique. When the magnetic body 17 slides, it directly acts on the lines of magnetic force generated in the secondary coil 8, so as shown in FIG. voltage (thick line).

The push spring 18 expands and contracts within the differential transformer 5, and when it bends, it increases the density of the steel wire, increases the density of the magnetic lines of force, and increases the output voltage of the magnetic body 17 alone (thick line) as shown in the broken line in FIG. It outputs a voltage that is gradually increased to the position shown in Figure 3 (approximately 4
mm) When the magnetic body 17 moves, the induced voltage becomes about 4.5V. In other words, when the magnetic body 17 moves by 4 mm,
The amount of voltage change is 4.5V, which is a large value, and it is easy to perform the discrimination process using the circuit shown in FIG.

〔Effect of the invention〕

According to the present invention, by providing a pressure spring on the inner diameter of the magnetic body that resists the buoyancy of the diaphragm, a form is created in which the reactance change created by the sliding of the magnetic body and the reactance change created by the change in the iron content of the compression spring are combined. Because it can be taken out with
This allows the entire product to be made smaller.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention, and FIG.
3 is a front sectional view showing one embodiment of the present invention, FIG. 4 is an exploded perspective view showing one embodiment of the present invention, and FIG. 5 is a drive circuit diagram of one embodiment of the present invention. FIG. 6 is a characteristic diagram of an embodiment of the present invention. 1...Base, 2...Cylindrical part, 5...Differential transformer, 7...Primary side coil, 8...Secondary side coil,
9...Diaphragm, 11...Sliding body, 12...
Disc body, 13...Hollow shaft, 17...Magnetic material, 18
... Pressure spring, 20 ... Adjustment screw.

Claims (1)

[Scope of Claims] 1. A diaphragm that is displaced in response to changes in pressure, a sliding body that is applied to the opposite side of the pressure-receiving surface of the diaphragm, a pressure spring that is provided to resist the pressure-receiving pressure of the diaphragm, and a pressure spring that is provided on the sliding body. In a displacement detector consisting of a magnetic material and a coil that is magnetically inductively coupled to the magnetic material and whose inductance changes according to the movement of the magnetic material, the magnetic material is placed inside the coil and formed into a cylindrical shape, A displacement detector characterized in that a pressure spring is placed inside a magnetic body.