JPS5818187Y2 - Proximity switch - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a high frequency oscillation type proximity switch whose operation can be confirmed by a light emitting element.

A high-frequency oscillation type proximity switch is composed of a detection coil section, an oscillation circuit including the detection coil section, and a switching circuit that performs a switching operation depending on the oscillation state of the oscillation circuit.

When an object approaches the detection coil, the oscillation state of the oscillation circuit changes, and based on this, a detection output is output from the switching circuit.

By the way, since this proximity switch is often used in adverse environments, the detection coil section and circuit section are completely sealed.

As shown in Fig. 1, in a conventional proximity switch, a coil 1 is wound around a synthetic resin coil bobbin 11 and is housed in a core 12 made of ferrite or the like to form a coil part, and a residual circuit part 2 is printed. It is formed on the substrate 21.

The detection coil section and the circuit section are housed in a bottomed cylindrical case 3 made of transparent synthetic resin, and are further filled with transparent synthetic resin 31 to fix them.

The opening at the rear end of the case 3 has a cap 32 made of an elastic material such as rubber, and a press plate 3 for holding the cap 32.
3 and are closed and sealed.

Note that the cable 23 forming the power supply line and the signal line is drawn out to the outside without impairing the sealing performance of the case 3.

A metal mounting cylinder 4 is attached to the outside of the case 3, and the two are integrated.

This cylindrical body 4 is for attachment, and has a male threaded portion 41 formed on its outer periphery.

That is, the proximity switch is attached to the male threaded portion 41 with a nut or the like.

The circuit section 2 is equipped with a light emitting diode LED 22 for operation confirmation, and a window section 42 is provided in the cylindrical body 4 to guide the light of this LED 22 to the outside. transparent material is used.

However, transparent synthetic resins are generally more susceptible to organic solvents and have lower environmental resistance than opaque synthetic resins.

Since organic solvent-based cutting fluids are often used as cutting fluids in machine tools, etc., this often lands on the exposed front end portion of the case 3, which is a problem.

In other words, since the exposed front end portion of the case 3 has the detection coil section disposed inside it, it is normally formed to be extremely thin (for example, 0.5 to 1.0 mm') in order to increase sensitivity. This is because if the case of this part is damaged by solvent or the like, water or the like will enter the detection coil part, causing malfunction.

Also, making the case 3 transparent like this is not good in terms of appearance.

In other words, the coil part is visible from the front end,
Generally, it often gives a weak image,
This is because it lowers the product value and is not desirable.

An object of the present invention is to provide a proximity switch that is configured to be able to guide light from a light emitting element for operation confirmation to the outside, and that has improved environmental resistance.

Examples of the present invention will be described below.

In FIG. 2, the synthetic resin case consists of a portion 34 made of opaque synthetic resin located on the front side of the core 12 and a portion 35 made of transparent synthetic resin on the rear end side.

This synthetic resin case is made as follows.

First, a bottomed cylindrical front part 34 is made of opaque synthetic resin by insert molding so as to include the core 12 containing the coil 1 and the like.

On the other hand, a cylindrical case portion 3 with open ends, which includes the metal cylinder 4 and is fixed to the cylinder 4 by insert molding, covers the inner surface of the cylinder 4 and fills the window 42.
Make 5.

Then, the portion 34 including the core 12 is inserted into the front end of the cylindrical body 4, and the end surface of the opaque resin portion 34 and the end surface of the transparent resin portion 35 are butted together.

By applying ultrasonic waves in this state, the abutting portions are melted and the image portions 34 and 35 are joined.

For this reason, both transparent and opaque synthetic resins must be thermoplastic.

In this way, the end faces of the two parts 34 and 35 are welded and integrated to form one synthetic resin case.

In addition, a protrusion 36 is provided on one of the end faces of the two parts 34 and 350 to be butted as shown in FIG. 3, and the ultrasonic energy is concentrated on this protrusion 36, facilitating ultrasonic welding. It is preferable that the

It is preferable to form an uneven portion on the inner surface of the cylindrical body 4 prior to resin molding so that the case 35 does not fall out.

FIG. 4 shows a second embodiment, in which the coil bobbin 13 is integrally molded with the front plate 37 of the synthetic resin case.

A cylindrical transparent resin portion 38 located on the inner surface of the cylinder 4 is a second
It is made by insert molding as shown in the figure.

In the case of the embodiment shown in FIG. 4, a front plate 37 integrally having a coil bobbin is molded from opaque synthetic resin, and the coil 1 is wound around this bobbin 13.

Then, the core 12 and the front plate 37 are combined and integrated so that the coil 1 is housed in the recess of the core 12.

Next, the core 12 is inserted into the front end of the cylindrical transparent resin part 38, the end of the front plate 37 and the end of the transparent part 38 are butted together, and the image part 37 is ultrasonically welded as in FIG. ,3
It integrates 8.

In addition, in FIGS. 2 and 4, the same parts as in FIG. 1 are given the same numbers and the explanations are omitted.

As explained in the above embodiments, according to the present invention, the case that covers the front surface of the detection coil part and is exposed from the mounting cylinder is made of opaque synthetic resin, and the inside of the cylinder and the window part are covered. The front end of this case is made of opaque synthetic resin, which prevents it from being affected by various solvents and prevents the detection coil from being adversely affected by water. can lead to.

Moreover, since the mounting cylinder is cylindrical, there is a risk that the internal case may rotate or shift position, but in this invention, the window part is filled with transparent synthetic resin as described above. Since the transparent synthetic resin part of the case is formed by insert molding, the positioning is ensured to prevent rotation or other misalignment due to the action of the resin filled in this window part. Since the window portion is filled with resin, the light from the light emitting element is transmitted through the transparent synthetic resin and radiated into the air at the surface of the mounting cylinder, making it possible to realize an easier-to-read display.

Since only the front end of the synthetic resin case is made of opaque synthetic resin, this part is prepared in various colors and can be colored differently depending on the type of proximity switch. It would be convenient if you could use one.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view showing the conventional example, and Figure 2 is the first example of the present invention.
FIG. 3 is a longitudinal sectional view showing an enlarged part of FIG. 2, and FIG. 4 is a longitudinal sectional view showing the second embodiment. 1...Detection coil, 11, 13...Coil bobbin, 2...Circuit section, 22...
LED, 3...Resin resin case, 34, 37.
...Parts made of opaque synthetic resin, 35, 38...
... Part made of transparent synthetic resin, 4 ... Metal mounting cylinder, 42 ... Window part.

Claims (1)

[Scope of utility model registration request] The detection coil section and the circuit section are housed and sealed inside a synthetic resin case, and a metal mounting cylindrical body is attached to the outside of the case to guide light from a light emitting element for confirming the operation of the circuit section. In the proximity switch provided in the cylindrical body having a window portion, the synthetic resin case includes a portion made of opaque synthetic resin located in front of the detection coil portion and a transparent synthetic resin covering the inside of the cylindrical body. A proximity switch comprising a transparent synthetic resin portion formed by insert molding so that the inside of the window portion is filled with transparent synthetic resin.