JPH0528771B2 - - Google Patents

Description

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

[Conventional technology]

Currently, there are many examples of using displacement detectors equipped with coils and diaphragms to control electronic equipment, etc., but many of the conventional examples, such as ``Japanese Patent Application Laid-Open No. 17656/1983'', show the operating principle. There is nothing specified in detail.

The present invention has been made in view of this point, and at the same time specifies the overall component structure and defines the attachment of the magnetic body (core) that influences the overall size of the product.

[Problem that the invention seeks to solve]

Magnetic flux is generated around the coil, and when a magnetic object approaches, the magnetic flux increases and the reactance of the coil changes. Normally, the magnetic material is moved within the entire length of the coil, but in order to increase the output, the stroke of the magnetic material is increased. As a result, the winding width of the coil increases, and the overall size of the product increases when the installation of the coil is taken into account. The present invention focuses on the surroundings of the coil that is affected by magnetic flux,
That is, the outside of the end face of the coil is used as the starting point of the magnetic material operation, and a large output is attempted to be obtained regardless of the winding width of the coil.

[Means for solving problems]

The present invention includes a coil, a diaphragm that is displaced by receiving pressure, and a sliding body provided so as to be applied to the opposite side of the pressure-receiving surface of the diaphragm.
In a device that is attached to a sliding body and consists of a magnetic body that is magnetically inductively coupled to a coil, a cylindrical part is formed on a synthetic resin base in which a diaphragm is placed, and a coil is attached to the outer periphery of this cylindrical part. , a bearing part for slidably supporting the sliding body is formed at the upper end of the cylindrical part, the magnetic body is formed in a circular shape, and the outer periphery of the magnetic body slides on the inner periphery of the cylindrical part. The coil is placed in the cylindrical part so that the range of movement of the magnetic body due to diaphragm displacement is defined within the cylindrical part, and the upper end of the magnetic body is in a position lower than the lower end of the coil when no pressure is applied to the diaphragm. It is characterized by being located above the lower end.

[Effect]

As a result, the stroke of the magnetic body can be increased without increasing the winding width of the coil, and therefore, the output, which is difficult to detect, can also be increased.

[Embodiments of the invention]

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

1 is a rigid base molded from ABS 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 φ17 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 circular magnetic body 17 is arranged inside the cylindrical portion 2 . The magnetic body 17 moves up and down, and the outer periphery of the magnetic body 17 slides on the inner periphery of the cylindrical portion 2 during this vertical movement. Also, inside the base 1, there is a thin film diaphragm 9 having a pressure receiving surface 10 and a base part 19 made of cloth-filled rubber, a disc body 12 that comes into contact with the pressure receiving surface 10, and a screw thread perpendicular to the diaphragm 9. A hollow shaft 13 and a circumferential wall with a fitting protrusion 1
A rigid sliding body 11 made of polyacetal resin containing oil or paraffin and having four circumferential grooves 15 is provided. The buoyancy of the diaphragm 9 is applied uniformly on each side to maintain the
Slide the bearing port 4. Hollow shaft portion 13 of sliding body 11
An adjustment screw 20 made of a rigid body molded from polyaotal resin has one end in contact with the base portion 19, and by turning the adjustment screw 20, the slider 11 is moved from the base portion 19.
and the magnetic body 17 are engaged so that fine adjustment can be made up and down. Further, the circumferential wall portion 14 is provided with a magnetic material 17 made of a circular steel plate made of permalloy or ferromagnetic material.
The cut groove 25 and the guide protrusion 26 are aligned so that the guide can be positioned in a fixed direction, and the fitting protrusion 16 is used to removably insert and fix the guide protrusion 26. Furthermore, a pressure adjustment spring 18 is provided in the circumferential groove portion 15 to adjust the amount of movement of the sliding body 11 against the buoyancy of the diaphragm 9.
The sliding body 11 is biased based on the surrounding inner surface, and the magnetic body 1
It is located inside the differential transformer 7 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 is received and the disc body 1 is pushed against the pressure adjustment spring 18.
Press up each side of 1 evenly. Therefore, the magnetic body 17
slides from the outside to the inside of the end face of the secondary coil 8, maintaining a uniform gap with the inner peripheral part of the differential transformer 5 without being oblique. As 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. This is the output voltage (thick line).

The pressure adjustment 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 causes the magnetic body 1 to expand and contract as shown by the broken line in FIG.
7 outputs a voltage that is gradually added to the output voltage (thick line) alone, and when the magnetic body 17 moves to the position (approximately 4 mm) as shown in Figure 3, the induced voltage becomes 4.5V.
It will be about. In other words, when the magnetic body 17 moves 4 mm, the voltage change amount is 4.5V, which is a large value, and the fifth
It is easy to perform the discrimination process using the circuit shown in the figure.

〔Effect of the invention〕

The present invention includes a coil, a diaphragm that is displaced by receiving pressure, and a sliding body provided so as to be applied to the opposite side of the pressure-receiving surface of the diaphragm.
In a device that is attached to a sliding body and consists of a magnetic body that is magnetically inductively coupled to a coil, a cylindrical part is formed on a synthetic resin base in which a diaphragm is placed, and a coil is attached to the outer periphery of this cylindrical part. , a bearing part for slidably supporting the sliding body is formed at the upper end of the cylindrical part, the magnetic body is formed in a circular shape, and the outer periphery of the magnetic body slides on the inner periphery of the cylindrical part. The coil is placed in the cylindrical part so that the range of movement of the magnetic body due to diaphragm displacement is defined within the cylindrical part, and the upper end of the magnetic body is in a position lower than the lower end of the coil when no pressure is applied to the diaphragm. The detector is characterized in that it is arranged above the lower end.

This configuration has the following advantages.

(1) The coil is arranged above the bottom end of the cylindrical part so that the top end of the magnetic body is located below the bottom end of the coil when no pressure is applied to the diaphragm. Even if the winding height is small, the change in reactance of the coil due to the movement of the magnetic material is large and the detection sensitivity is good.

(2) The upper side of the sliding body is slidably supported on the bearing part,
Since the outer periphery of the magnetic material attached to this sliding body slides on the inner periphery of the cylindrical part, when the magnetic material moves up and down, there is very little vibration in the circumferential direction, which prevents errors in detection. I won't come.

Since this device has high detection sensitivity with a large reactance change, detection errors are likely to occur due to vibrations of the magnetic material in the circumferential direction, and it is important to suppress such fluctuations.

[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 adjustment spring, 20 ...Adjustment screw.

Claims (1)

[Claims] 1. A coil, a diaphragm that is displaced by receiving pressure, a sliding body provided so as to be placed on the opposite side of the pressure-receiving surface of the diaphragm, and a sliding body that is attached to the sliding body and that is magnetically inductively connected to the coil. A cylindrical part is formed on a synthetic resin base in which a diaphragm is placed, a coil is attached to the outer periphery of this cylindrical part, and the sliding body is slid on the upper end of the cylindrical part. A bearing part is formed to freely support the magnetic body, the magnetic body is formed into a circular shape, and the outer periphery of the magnetic body is arranged so as to slide on the inner periphery of the cylindrical part, so that the movement range of the magnetic body due to diaphragm displacement is limited. Displacement defined in the cylindrical part, characterized in that the coil is arranged above the lower end of the cylindrical part so that the upper end of the magnetic body is in a position lower than the lower end of the coil when no pressure is applied to the diaphragm. Detector.