JP2001155606A - Float-type liquid level detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a float-type liquid level detector where the workability is superior in production as well as preventing the glass tube of a lead switch fro being destroyed without impairing water sealing function even at an increased temperature. SOLUTION: A float-type level detector comprises a lead switch 2 installed in a cylindrical guide 1, ion whose periphery is fitted by a float 3 with a magnet, which changes its position according to a rise or fall if the liquid level to turn on/off the lead switch 2. The lead switch 2 is enclosed by a heat shrinking tube 9 lined with a heat-fusible adhesive layer 10, which is heat-treated so as to seal the lead switch 2 together with its junctions 11a, 11b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a float type liquid level detector, and more particularly, to a float with a magnet fitted on the outer periphery of a cylindrical guide having a reed switch therein as the liquid level rises and falls. Turn the reed switch ON-OFF
The present invention relates to a float type liquid level detector.

[0002]

2. Description of the Related Art Conventionally, in this type of liquid level detector, an epoxy resin is filled in an upper end opening of a cylindrical guide in which a reed switch is provided, and a water sealing structure is provided.
As shown in FIG. 1, a resin 109 is filled in a cylindrical guide 101 in which a reed switch 102 is provided, and a reed switch 1 is provided.
02 was adopted as a water sealing structure.

[0003]

However, in the case of a float type liquid level detector in which an epoxy resin is filled in the opening at the upper end of the cylindrical guide, if it is used in a high temperature liquid, the lead wire The release agent emerges from the vinyl chloride coating, deteriorating the adhesive effect with the epoxy resin, and the external liquid enters the cylindrical guide through the gap to corrode the lead pieces. Also, the resin 109 is placed in the cylindrical guide 101.
When the reed switch 102 is molded by filling the resin, there is a serious drawback that when the temperature is increased, the reed switch 102 is pressed by the thermal expansion of the resin and the glass tube is broken, and workability at the time of production is reduced. However, there is a disadvantage that the process cannot proceed to the next step unless the solidification of the filling resin is waited. Therefore, an object of the present invention is to provide a float type liquid level detection method that does not impair the water sealing function even at a high temperature, does not break the glass tube of the reed switch, and has excellent workability during production. Is to provide equipment.

[0004]

According to the present invention, a float with a magnet fitted to the outer periphery of a tubular guide containing a reed switch is displaced as the liquid level rises and falls to turn the reed switch on and off. In the liquid level detector, a heat-shrinkable tube having a heat-meltable adhesive layer formed on the inner peripheral surface is fitted over the outer peripheral surface of the reed switch and the periphery of the connection between the lead piece and the lead wire, and heat-treated. In this way, the outer peripheral surface of the reed switch and the periphery of the connection between the reed piece and the lead wire provided inside the cylindrical guide were covered in a watertight manner.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a reed switch 2 described later.
Is a tubular guide for fitting the float 3 to the outer peripheral surface, and a mounting structure 4 is attached to an upper portion of the outer peripheral surface, and a snap ring 5 is fitted to a lower end portion. Three
Is an annular float provided with a magnet 6, which is fitted on the outer periphery of the cylindrical guide 1 vertically suspended in the tank, and is displaced up and down as the liquid level in the tank rises and falls. In the reed switch 2, the lead pieces 7a and 7b come and go in the glass tube due to a change in the magnetic action of the magnet 6 accompanying the displacement of the float 3 with a magnet. Are connected to lead wires 8a and 8b, respectively. 9 is a heat-shrinkable tube made of, for example, polyolefin or Teflon,
As shown in detail in FIG. 2, it has a two-layer structure in which a resinous hot-melt adhesive layer 10 is formed on the inner peripheral surface.

As shown in detail in FIG. 3, the outer peripheral surface of the reed switch 2 and the lead pieces 7a and 7b and the lead wire 8
When the heat-shrinkable tube 9 is fitted around the connection parts 11a and 11b with the heat-shrinkable tube 9a and 8b and heat-treated with a drier or the like, the heat-meltable adhesive layer 10 is melted as shown in FIG. And heat-shrink tubing 9
Shrinks and comes into close contact with the above-described portions, so that the outer peripheral surface of the reed switch 2 and the lead pieces 7a, 7b and the lead wires 8a, 8a,
The periphery of the connection portions 11a and 11b with the 8b is covered in a watertight manner. In this manner, the reed switch 2 in which the portion required for water sealing is covered in a water-tight manner is accommodated in the cylindrical guide 1, and the extending portions of the lead wires 8a and 8b are formed as shown in FIG. 1 is opened from the upper end opening, and the opening is covered with a packing 12 and a fastening structure 13. These operations are immediately performed without waiting time after completion of the heat treatment by the dryer or the like. You get it.

[0008]

According to the present invention, a heat-shrinkable tube having a hot-melt adhesive layer formed on the inner peripheral surface thereof is fitted and heat-treated to cover the reed switch and its connection area in a watertight manner. Therefore, even if the external liquid enters the cylindrical guide, the lead piece does not corrode. Also, even if the temperature rises, the resinous adhesive softens and does not put a burden on the reed switch, so that the resin is filled in the cylindrical guide and the reed switch is molded as in the conventional water sealing structure. No reed switch breakdown due to thermal expansion will occur. Furthermore, the heat treatment of the hot-melt adhesive layer and the heat-shrinkable tube can be easily performed using a drier or the like, and the process can immediately proceed to the next step without waiting for solidification of the filling resin as in the related art.
There is an advantage that work efficiency during production is good.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a float type liquid level detector illustrating an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a heat-shrinkable tube used in the float type liquid level detector of the present invention.

FIG. 3 is a vertical sectional side view showing a state in which the heat-shrinkable tube of FIG. 2 is fitted around a reed switch and a connection portion thereof.

FIG. 4 is a longitudinal sectional side view showing a state in which the heat-fusible adhesive layer is melted by heat treatment from the state of FIG. 3 and the heat-shrinkable tube is shrunk.

FIG. 5 is a vertical sectional side view illustrating a water sealing structure in a conventional float type liquid level detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical guide 2 Reed switch 3 Float 6 Magnet 7a Lead piece 7b Lead piece 8a Lead wire 8b Lead wire 9 Heat-shrinkable tube 10 Hot-melt adhesive layer 11a Connection part 11b Connection part

Claims (1)

[Claims] 1. A float type liquid level detector in which a float with a magnet fitted to the outer periphery of a cylindrical guide containing a reed switch is displaced as the liquid level rises and lowers to turn the reed switch on and off. A heat-shrinkable tube having a heat-meltable adhesive layer formed on the inner peripheral surface thereof is fitted over the outer peripheral surface of the switch and around the connection between the lead piece and the lead wire, and is subjected to heat treatment to thereby provide a cylindrical guide. A float type liquid level detector, wherein an outer peripheral surface of the reed switch and a periphery of a connecting portion between a lead piece and a lead wire are water-tightly covered.