JPH06342987A - Waterproofing structure for electric component and insert molding method for forming the same structure - Google Patents

Abstract

PURPOSE:To provide a waterproofing structure for an electric component and an insert molding method for forming the same structure. CONSTITUTION:A waterproofing structure for an electric component comprises the component 1, and a cable 2 connected to the component, wherein the component 1 and its end 4 are covered with resin 5 by insert molding in a state that an O-ring 4 is engaged with an outer periphery 4 of an end of the cable 2. A method for insert molding the structure comprises the steps of disposing the component 1 and the end 4 of the cable 2 connected to the component 1 and engaged at its outer periphery with the ring 7 in a cavity 9 of an insert mold 8, and insert molding the ring 7 in a state of disposition near a gate 10. Accordingly, its structure is simple, and an effective waterproof effect and excellent external appearance are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waterproof structure for electric parts and an insert molding method for forming the waterproof structure.
In particular, the present invention relates to a waterproof structure of an electric component having a simple structure and excellent appearance, and an insert molding method suitable for forming the waterproof structure.

[0002]

2. Description of the Related Art Electrical components such as sensors used in places that may be flooded or in water have a waterproof structure.
In order to provide a waterproof structure, a method of covering the electric parts and the tip of a cable connected to the electric parts with a resin has been conventionally used. FIG. 4 shows a conventional waterproof structure for electric parts. For example, an electric component 1 including a temperature sensor such as a thermistor is connected to a core wire 3 of a cable 2 covered with soft vinyl chloride having a hardness of about 40 to 92 degrees, and the electric component 1 and a tip portion 4 of the cable 2 are connected. Has a hardness that is usually
It is covered with a resin 5 such as soft polyvinyl chloride having a temperature of 40 to 92 degrees. However, since there is a risk that water will infiltrate from the boundary between the resin 5 and the cable 2 as it is, the portion is further sealed with a sealing material 6 such as a flexible adhesive.

[0003]

However, such a conventional waterproof structure requires a sealing step after insert molding, which is troublesome to manufacture and
There is a problem that it is difficult to achieve a stable sealing effect due to differences in adhesiveness and thermal expansion between the sealing material and the cable. Further, there is a problem that the seal portion is likely to be non-uniform, and therefore the appearance is not good. Therefore, an object of the present invention is to provide a new waterproof structure for electric parts that solves such problems, and an insert molding method for forming the waterproof structure.

[0004]

That is, the waterproof structure for an electric component of the present invention is a waterproof structure in which the tip of the electric component and a cable connected to the electric component is resin-coated by insert molding. It is characterized in that it is resin-coated with an O-ring fitted on the outer periphery. Further, in the insert molding method for forming the waterproof structure, the tip of the cable 2 connected to the electric component and fitted with an O ring on the outer periphery is arranged in the cavity of the insert molding die, and the O It is characterized in that the ring is positioned near the gate and is insert-molded for resin coating.

[0005]

In the waterproof structure for electric parts according to the present invention, the O-ring is fitted on the outer circumference of the tip of the cable, and the O-ring prevents the water from entering from the gap between the outer circumference of the cable and the resin. Be blocked. Therefore, it is possible to surely protect the electric component and its connecting portion from water infiltration. Further, according to the insert molding method of the present invention for forming the waterproof structure of the electric component, the O-ring fitted on the outer periphery of the tip end portion of the cable is inserted in the vicinity of the gate which is the resin injection port to the cavity. Since molding is performed, escape of the O-ring during molding can be effectively prevented. Therefore, the positioned O-ring can be reliably maintained for molding, and a desired waterproof structure can be formed with good reproducibility.

[0006]

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 is a partial cross-sectional view showing an example of the waterproof structure for an electric component of the present invention, and FIG. 2 is an enlarged cross-sectional view of a II part thereof. In these figures, the same parts as those in FIG. 4 described above are designated by the same reference numerals. An O-ring 7 is fitted on the outer circumference of the tip 4 of the cable 2 to which the electric component 1 is connected. In this embodiment, the outermost peripheral covering material of the cable 2 is made of soft vinyl chloride having a hardness of about 75 degrees. Also, as an example, O-ring 7
Uses natural rubber with a hardness of about 50 degrees. Note that other known soft elastic materials are used for the cable covering material, and the hardness is 40%.
It is possible to set the degree to about 92 degrees. Furthermore, the O-ring is
It consists of a ring with hardness of 40 to 90 degrees and elasticity such as natural or synthetic rubber such as propylene or elastic plastic, and its inner diameter is slightly smaller than the outer diameter of the tip 4 of the cable 2, By enlarging and fitting it at a predetermined position of the tip portion 4, it fits into the outer periphery of the tip portion 4 by biting. The tip portion 4 of the cable 2 in which the O-ring 7 is fitted together with the electric component 1 is covered with the resin 5 by insert molding. The resin 5 is, for example, made of a soft vinyl chloride material having a hardness of about 75 degrees. The hardness is appropriately selected within the range of 40 to 92 degrees. Due to its elasticity, the O-ring 7 is brought into close contact with both the outer periphery of the tip portion 4 of the cable and the resin 5 after molding, thereby ensuring the sealing property of this portion.

FIG. 3 is a view for explaining an example of the insert molding method of the present invention for forming the waterproof structure of the electric component, and shows a molded state in an enlarged manner. A pair of gates 10 are provided in the cavity 9 of the insert molding die 8 used, and a runner 11 for supplying resin is connected to the gates 10. The procedure of molding using the insert molding die 8 will be described. First, the distal end portion 4 of the cable 2 in which the O-ring 7 is fitted together with the electric component (not shown) is arranged in the cavity 9. At that time, the O-ring 7 is positioned near the gate 10, preferably on the axis of the gate 10.

Next, the molten resin is supplied from the runner 11 to each gate 10 and injected into the cavity 9. The molten resin is injected at high speed from the gate 10 and flows in the cavity 9, but since the gate 10 is at the position of the O-ring 7, the flow of the molten resin in the cavity 9 causes the O-ring 7 to move in the longitudinal direction of the cable. There is nothing to do. After the resin is solidified, the insert molding die 8 is opened, whereby the tip 4 of the electric component 1 and the cable 2 connected to it and fitted with the O-ring 7 as shown in FIG. 1 is covered with the resin 5. A waterproof structure is obtained.

Examples of electric parts to which the waterproof structure of the present invention can be applied include various waterproof sensors, electric plugs, solenoid valves, and switches. As the sensor, there are a temperature sensor, a pressure sensor, an optical sensor, a proximity switch, and the like. When applying the waterproof structure of the present invention to the optical sensor, a transparent resin is used. It is also applied to the waterproof structure of the power cable of the submersible pump and the casing of the pump. In this case, the O-ring is attached to the outer periphery of the casing penetration part,
A brim-shaped bush made of soft vinyl chloride is integrally molded on the outer periphery of the portion. Then, by fastening the brim-shaped bush to the casing by an appropriate means, a highly reliable waterproof structure can be provided.

[0010]

Since the waterproof structure for electric parts of the present invention is resin-coated with the O-ring fitted on the outer periphery of the tip of the cable, water will not leak from the gap between the outer periphery of the cable and the resin. The ring is positively blocked and the electrical components and their connections can be protected from flooding. Further, since the waterproof structure of the electric component of the present invention is made by the O-ring embedded in the resin as described above, it is not necessary to further seal the boundary portion between the resin and the cable with the sealing material as in the conventional case, and therefore the appearance The property is also good. Further, the insert molding method of the present invention is a method suitable for forming the waterproof structure of the electric component. In the molding method, the O-ring fitted on the outer circumference of the tip end portion of the cable is insert-molded so as to be positioned near the gate that is the resin injection port to the cavity. It can be effectively prevented. Therefore, the positioned O-ring can be reliably maintained for molding, and a desired waterproof structure can be formed with good reproducibility.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an example of a waterproof structure for electric parts of the present invention.

FIG. 2 is an enlarged sectional view of a portion II of FIG.

FIG. 3 is a view for explaining an example of an insert molding method for forming a waterproof structure for electric parts of the present invention.

FIG. 4 is a partial cross-sectional view showing a waterproof structure of a conventional electric component.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric component 2 Cable 3 Core wire 4 Tip part 5 Resin 6 Seal material 7 O-ring 8 Insert molding die 9 Cavity 10 Gate 11 Runner

Claims (2)

[Claims] 1. In a waterproof structure in which an electric component 1 and a tip 4 of a cable 2 connected to the electric component 1 are resin-coated by insert molding, the outer circumference of the tip 4 of the cable 2 is O.
A waterproof structure for an electric component, characterized in that the ring 7 is resin-coated in a fitted state. 2. A cavity 9 of an insert molding die 8.
The electrical component 1 and the O-ring 7 connected to it and on the outer periphery
In order to form a waterproof structure of an electric part, which is characterized in that the tip end portion 4 of the cable 2 fitted with the O-ring 7 is arranged, and the O-ring 7 is positioned near the gate 10 and insert-molded for resin coating. Insert molding method.