JPH0227670Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an acoustic sensor used underwater, and particularly to a watertight structure for an underwater acoustic sensor that can endure long-term use and withstand environmental changes.

[Conventional technology]

Underwater acoustic sensors use electroacoustic components such as elements that transmit and receive sound waves, and these electroacoustic components must be insulated from the outside air and have a watertight structure that allows easy passage of sound waves.

The conventional watertight structure of such an underwater acoustic sensor will be explained based on FIG. 2.

FIG. 2 is a side sectional view of a conventional example. In Fig. 2, 1, 2, 3 are wave transmitting/receiving elements, 4, 5, 6, 7
8 and 9 are packings such as urethane rubber used as a cushioning material and airtight maintenance material when fixing the wave transmitting and receiving elements 1, 2, and 3; A fixing plate, 10 is a rubber cable for transmitting electrical signals to the outside, 11 is an electroacoustic component made up of the above-mentioned components, and 12 has rubber elasticity for maintaining insulation in close contact with the electroacoustic component 11. It is mold resin. Incidentally, in the center of one of the fixing plates 8 described above, a protrusion 8a is formed and an insertion hole 8b into which the cable 10 is inserted is bored.

In the underwater acoustic sensor configured as described above, the connecting wires of the cable 10 are connected to the wave transmitting/receiving elements 1, 2, and 3 by soldering or the like, and the both sides of each of the wave transmitting/receiving elements 1, 2, and 3 are connected to the gaskets 4, respectively. ,5,
6 and 7 and fixed with fixing plates 8 and 9, the electroacoustic component 11 is assembled as shown in FIG. 2, and its periphery is closely covered with mold resin 12 to form a watertight structure.

[The problem that the invention attempts to solve]

However, although such conventional examples can withstand normal use underwater, they may be used in special environments, such as when used continuously underwater or in places with rapid temperature changes, such as the following. A problem arises.

In other words, when an underwater acoustic sensor is subjected to changes in water pressure or temperature, the difference in linear expansion coefficient between the wave transmitting/receiving element and the molded resin may cause distortion at the adhesive interface between them, which may cause peeling. Depending on the type of molded resin that covers the electroacoustic parts,
There is a problem that hydrolysis may occur, and moisture permeation may cause a decrease in adhesive strength and insulation.

As described above, in the watertight structure of conventional underwater acoustic sensors, it is essentially difficult to completely prevent peeling due to thermal stress and moisture permeation of the mold resin itself. Therefore, the present invention was devised to solve the above problem, and its purpose is to provide an underwater acoustic sensor that can withstand environmental changes and can withstand long-term use.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention includes a metal case that houses an electroacoustic component consisting of a packing, a wave transmitting/receiving element, etc., and a rubber-based case that is provided between the metal case and the electroacoustic component to cover the electroacoustic component. It is characterized by being made of a soft resin and a mold resin that covers the metal case.

[Effect]

The present invention having the above-mentioned characteristics includes storing an electroacoustic component in a metal case, providing a rubber-based soft resin with good adhesion between the metal case and the electroacoustic component, and covering the electroacoustic component. The metal case is coated with molded resin and integrated to stabilize its underwater performance over the long term.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 3. It should be noted that the same parts as in the conventional example are given the same numbers and their explanation will be omitted.

FIG. 1 is a side view showing an embodiment of the watertight structure of an underwater acoustic sensor according to the present invention, and FIG. 3 is a perspective view showing an example of a metal case used in the embodiment of the present invention. In FIG. 1, wave transmitting/receiving elements 1, 2, 3, packing 4,
5, 6, 7, fixed plates 8, 9, and cable 10,
Although it is the same as the conventional example and the method of assembling them is also the same, the points described later are different. That is, 12 is a rubber-based soft resin that has good adhesion to the electroacoustic component 11 and good acoustic transparency, and 13 is a molded resin with rubber elasticity for maintaining insulation from the outside.

In addition, in Fig. 2, 14 is a metal case,
It consists of a bottomed cylindrical main body 14a that houses the electroacoustic component 11 and a lid 14b, and the lid 14b has a hole 14c in the center into which the protrusion 8a of the fixing plate 8 is inserted.
An injection port 14 for injecting the rubber-based soft resin 12 is provided at the side of the hole 14c.
d is perforated. 15 is a spacer for insulating the metal case 14 and the electroacoustic component 11.

Incidentally, the thinner the metal case 14 is, the softer it is, the lower the acoustic transmission loss will be. However, considering workability, solderability, etc., the thickness is, for example, 0.05 to 0.2 mm.
Copper-based or aluminum-based ones are good. Further, it is preferable that the gap between the outer surface of the electroacoustic component 11 and the inner surface of the metal case 14 be as small as possible.
However, depending on workability and the frequency band used, better results were obtained when the distance was within 1.5 mm. Furthermore, in order to improve the adhesion of the rubber-based soft resin 12 between the main body 14a of the metal case 14 and the lid 14b, a lid 14b is provided on the inner surface of the main body 14a.
It is made to fit.

Next, to explain the operation of the above configuration, first, the connection wires of the cable 10 are connected to the wave transmitting/receiving elements 1, 2,
3 by soldering, etc., and the both sides of each transceiver element 1, 2, 3 are connected to packing 4,
5, 6, and 7, and fixed with fixing plates 8, 9, and the electroacoustic component 11 is assembled as shown in FIG.

Then, the electroacoustic component 11 is housed approximately in the center of the metal case 14 with the opening of the main body 14a facing upward, with a spacer 15 for maintaining insulation being interposed therebetween, and a lid 14b is placed over the opening of the main body 14a as shown in FIG. After fitting, the rubber-based soft resin 12 is injected from the injection port 14d of the lid 14b. As a result, the electroacoustic component 11
Since it is covered with the rubber-based soft resin 12 and covered with the thin metal case 14 without any gaps, it is possible to sufficiently follow the thermal stress caused by changes in the outside air temperature, thereby preventing the peeling phenomenon. What to note here is that
It is necessary to prevent air bubbles from remaining inside the metal case 14 as much as possible, because remaining air bubbles will result in a loss of sensitivity in transmitting and receiving waves.

After that, in addition to fixing the cable 10 used for transmitting signals to the outside, in order to protect the electroacoustic component 11 from external impact and prevent corrosion,
As shown in FIG. 1, the metal case 14 is integrally covered with the molded resin 13 so as to be insulated from the outside.

It is also possible to use only the rubber-based soft resin 13 without using the metal case 14, but this would lead to a decrease in the strength of the underwater acoustic sensor in terms of handling, and it would be significantly different from the conventional method in terms of water permeability. Therefore, the metal case 14 is reinforced to prevent water permeation and further eliminate the peeling phenomenon. Furthermore, a method of using a plastic case instead of the metal case 14 is also conceivable. However, this plastic case has higher moisture permeability than the metal case 14, and also lacks adhesive strength with the mold resin 13, so it is somewhat less reliable.

[Effect of idea]

As described above, according to the watertight structure of the underwater acoustic sensor according to the present invention, the electroacoustic component is housed in a metal case, and a rubber-based soft resin with good adhesion is provided between the metal case and the electroacoustic component. By covering the electro-acoustic component, the metal case can completely prevent moisture from permeating from the outside, and also has the effect of preventing deterioration of the insulation of the electro-acoustic component. In addition, since a thin metal case is used, it can sufficiently follow thermal stress caused by temperature changes, and depending on the frequency band, the metal case can be easily designed by taking into account the thickness of the metal case and the spacing between the transmitting and receiving elements. . Therefore, it is possible to provide an underwater acoustic sensor of sufficiently stable quality even when used underwater for a long time or in a place where temperature changes are severe.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view showing an embodiment of the watertight structure of an underwater acoustic sensor according to the present invention, Fig. 2 is a side sectional view of a conventional example, and Fig. 3 is a metal used in an embodiment of the present invention. It is a perspective view showing an example of a case. 1, 2, 3... Wave transmitting/receiving element, 4, 5, 6, 7... Packing, 8, 9... Fixing plate, 10... Cable, 11
...Electroacoustic component, 12...Rubber-based soft resin, 13...
Mold resin, 14... Metal case, 14a... Main body, 14b... Lid, 14d... Inlet.

Claims (1)

[Scope of claim for utility model registration] In the watertight structure of an underwater acoustic sensor in which electroacoustic components such as packing and transceiver elements are covered with molded resin, the electroacoustic components are housed in a metal case, and the electroacoustic components are housed in a metal case. A watertight structure for an underwater acoustic sensor, characterized in that a rubber-based soft resin is provided between the parts to cover the electroacoustic parts.