JPH0610633Y2 - Liquid level sensor - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a liquid level sensor used when detecting the liquid level of an electrolytic solution or the like.

[Conventional technology]

A conventional liquid level sensor having, for example, the structure shown in FIG. 4 is disclosed in US Pat. No. 3,891,465. In this liquid level sensor, a lead 1 or lead alloy electrode 2 immersed in an electrolytic solution or the like is inserted into a case 1 made of an insulating material. The lead wire 3 is attached to the upper end portion of the electrode 2 with a compression sleeve 4.

When the liquid level sensor detects the liquid level, the lower end of the electrode 2 is immersed or brought into contact with a liquid such as an electrolytic solution to form a circuit via the electrode 2 and the lead wire 3.
Then, the current flowing through the lead wire 3 is sent to a dashboard or the like, where the liquid level is displayed by a lamp or a buzzer.

It is also known that the liquid level sensor itself has a function of displaying the liquid level, as shown in FIG. 5, instead of the display on the dashboard. In this case, the light emitting diode 5 and the resistor 6 are provided between the electrode 2 and the lead wire 3.
Have been inserted. Then, when the electrode 2 is immersed in or brought into contact with a liquid such as an electrolytic solution, the liquid level is notified by the light emission of the light emitting diode 5.

[Problems to be solved by the device]

Thus, when the electrode 2 is immersed in a liquid such as an electrolytic solution to detect the liquid surface level, the liquid easily enters the gap between the electrode 2 and the case 1. The invading liquid easily corrodes the connecting portion of the lead wire 3 in the upper part of the case 1, which causes a failure such as a disconnection. For example, if there is a disconnection, the circuit from the electrode 2 to the lead wire 3 is not configured, and the liquid level is not detected even though the electrode 2 is immersed in a liquid such as an electrolytic solution. Become.

Then, the present invention aims to provide a liquid level sensor which shows a stable performance for a long period of time by integrally molding the electrode part and the case body, thereby eliminating a gap into which a liquid such as an electrolytic solution enters. And

[Means for Solving the Problems]

In order to achieve the purpose, the liquid level sensor of the present invention is
The electrode part and the case body are integrally molded with conductive resin,
An inward protrusion protruding from the electrode portion into the case body is connected to a lead wire led out to the outside via a light emitting diode or a lead wire connected to a display portion such as a dashboard.

〔Example〕

Hereinafter, the features of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view for explaining a first embodiment in which the present invention is applied to a liquid level sensor having a light emitting display unit built therein.

In this liquid level sensor, the electrode portion 11 immersed in a liquid such as an electrolytic solution is integrally formed with the case body 12 by a conductive resin. As the conductive resin, metal powder,
A resin in which conductive particles such as carbon are dispersed is used. An inner protrusion 13 extending from the electrode portion 11 is provided inside the case body 12, and one leg portion 14 a of the light emitting diode 14 is attached to the inner protrusion 13 with a compression sleeve 15. Also, the other leg of the light emitting diode 14
A lead wire 16 extending to the outside is connected to 14b.

The case body that houses the light emitting diode 14 in this way
The interior space of 12 is filled with the filling material 17, and the transparent cap 18 is covered. As the filler 17, for example, a transparent material such as epoxy resin or silicone rubber is used.

FIG. 2 shows a second embodiment in which the present invention is applied to a liquid level sensor which adopts a system in which an electric current passing through the lead wire 16 is guided to a dashboard or the like, and a lamp, a buzzer or the like notifies the liquid level. Also in this embodiment, the electrode portion 11
The lead wire is attached to the inner protrusion 13 that protrudes from the
The ends of 16 are connected by a compression sleeve 15. Then, the filling material 17 is filled in the internal space of the case body 12.

FIG. 3 shows a liquid level sensor (first
(See the figure) is mounted on the battery. That is, the liquid level sensor 20 is attached to the top plate of the battery 21,
The electrode part 11 is projected into the battery 21. Then, connect the lead wire 16 derived from the liquid level sensor 20 to the battery.
21 is connected to the + side electrode 22.

When the liquid level of the electrolytic solution 23 contained in the battery 21 is at the high level L ₁ , the lower end of the electrode portion 11 is immersed in the electrolytic solution 23. As a result, the circuit of the electrolytic solution 23 → the electrode part 11 → the light emitting diode 14 → the lead wire 16 → the + side electrode 22 → the electrolytic solution 23 is constituted, and the light emitting diode 14 indicates that the electrolytic solution 23 is at the high level L _1. To be done. On the other hand, when the liquid level of the electrolytic solution 23 becomes the low level L _2, there is no current passing through the above-mentioned circuit,
The light emitting diode 14 is turned off. Thereby, it can be known that the liquid level of the electrolytic solution 23 is lower than the set value.

As described above, since the electrode portion 11 and the case body 12 are integrally molded with the conductive resin, for example, from the gap between the electrode 2 and the case 3 shown in FIGS. There is no risk of liquid entering the case 3. Therefore, the inner protrusion 13 and the lead wire inside the case body 12
The end portions, the connection parts such as the light emitting diode 14 are not corroded, and the electrical contact state is not deteriorated.

Further, the electrode portion 11 made of a conductive resin has a larger resistance value than an electrode made of metal such as lead. for that reason,
The electrode portion 11 can also be used as a resistor, and the resistor 6 shown in FIG. 5 can be omitted, for example, in a liquid level sensor incorporating the light emitting diode 14. Furthermore, since the resistance value changes according to the length of the electrode portion 11 immersed in the electrolytic solution 23, the brightness of the display portion such as the light emitting diode 14 changes. It is also possible to quantitatively know the electrolytic solution 23 contained in the battery 21 based on this change in brightness.

[Effect of device]

As described above, in the present invention, since the electrode part and the case body are integrally molded with the conductive resin,
There is no risk of liquid such as electrolyte entering the case.
Therefore, the connection part inside the case does not have poor contact, and a liquid level sensor that maintains stable detection performance for a long period of time can be obtained. Also, since the number of parts is reduced, the liquid level sensor can be easily assembled and the cost of the liquid level sensor itself can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the first embodiment of the present invention, and FIG.
FIG. 3 is a view for explaining the second embodiment, and FIG. 3 shows the liquid level sensor of the present invention attached to a battery. On the other hand, FIGS. 4 and 5 show a conventional liquid level sensor. 11: Electrode part, 12: Case body 13: Inner protrusion, 14: Light emitting diode 14a, 14b: Light emitting diode leg 15: Compression sleeve, 16: Lead wire 17: Filler, 18: Transparent cap 20: Liquid level Sensor, 21: Battery 22: + side electrode, 23: Electrolyte

Claims (1)

[Scope of utility model registration request] 1. A lead wire in which an electrode part and a case body are integrally molded with a conductive resin, and an inward projection protruding from the electrode part into the case body is led out to the outside through a light emitting diode. Or a liquid level sensor connected to a lead wire connected to a display part such as a dashboard.