JPS6022730B2 - Optical liquid level detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical liquid level detection device that detects the liquid level using an optical method.

Conventional methods for detecting the liquid level include using a float or using electrodes that hang down to the desired measurement liquid level, but these types of devices tend to be complicated and lack operational reliability. There are drawbacks.

The present invention relates to an optical liquid level detection device that has improved the above drawbacks, and is equipped with a light source and a photosensitive element at the base, a light entrance interface that hangs down to a specified liquid level at the tip, and a tapered side surface. It is characterized by having a light transmitting body with a reflective surface formed thereon. The present invention will be explained below with reference to FIG. 1 showing one embodiment thereof.

That is, in the drawing, 1 is a light source, and the light L emitted from the light source 1 is transmitted through a light transmitting body 2 made of glass or synthetic resin, particularly inexpensive materials such as polystyrene or polycarbonate.
and reaches the light incident interface 3. At this time, part of the light is irradiated onto the tapered total reflection surface on the side surface of the light transmitting body 2.
When there is a relationship of formula [1} between the incident angle 1, the refractive index Ns of the light transmitting body 2, and the refractive index Ne of the external fluid, all of the light is internally reflected and does not leak to the outside, and reaches the incident interface 3. Concentrate on. Plexus>Sim ‐・‐・‐・(1' Also, other extremely spread light passes through the light transmitting body 2 to the outside.

Next, the light L that has reached the light incident interface 3 is separated into refracted light L and reflected light S, but at this time, the amounts of the refracted light L and reflected light change due to the difference in the refractive index of the external fluid.

That is, when the light incident interface 3 is not in contact with the test liquid 4, the amount of reflected light L2 increases compared to when it is in contact. The reflected light L passes through the light transmitting body 2 again, reaches the photosensitive element 5 made of a phototransistor, and the light amount is measured. Based on the measured value, it is determined whether the light incident interface 3 is in contact with the test liquid 4 or not. It is detected whether the test liquid 4 is up to the specified liquid level. Now, the total reflection surface on the side surface of the light transmitting body 2 is connected to the light entrance interface 3 and 9.
Table 1 shows the results of comparing A with a 0o angle, that is, a side surface parallel to the ball direction, and 8 with a 63o taper as in the present invention.

Note that 30% sulfuric acid was used as the liquid to be tested. 1st
More than a table result? A tapered total reflection surface on the side surface of the light transmitting body as in the present invention has a better utilization efficiency of light, and also changes when the light entrance interface is in contact with the liquid to be measured and when it is not. It can be seen that this is remarkable.

Next, set the angle of the tip of the light transmitting body with the light entrance interface to 180o.
That is, Table 2 shows the results of measuring the current from the photosensitive element when the light incident interface was not in contact with the liquid to be tested when changing the shape from a flat shape to a shape of 200 mm.

From the results in Table 2 and above, it can be seen that the light utilization efficiency is better and the change is larger when the shape of the tip is angled than when it is planar.

Further, the current shows a maximum value at 110°, and its effect decreases below 400°. In view of this point, as shown in FIG. 2, one method is to configure the tip of the light transmitting body 2' to have an angle to form a light entrance interface 3'. Further, a description will be given with reference to FIGS. 3 and 4 showing other embodiments of the present invention.
In other words, this embodiment has a configuration including two light incident interfaces 3''a and 3''b, and as shown in FIG. The liquid level changes in a step-like manner, allowing you to know the liquid level in more detail.
It goes without saying that the number of light incident interfaces may be further increased. Although several embodiments of the present invention have been described above, for example, in order to eliminate detection malfunctions, it is possible to cover the optical transparent body with a light shielding material to block external light, etc., without departing from the scope of the claims. Various implementations are possible.

Next, various embodiments in which the present invention is applied to detecting the electrolyte level of a storage battery will be described.

In other words, in the optical liquid level detection device of the present invention, the liquid level detection part can be installed at a remote location or integrated with the storage battery, and in contrast to a device using electrodes, there is no possibility of corrosion or damage between the electrodes and the electrolyte. There is no drawback that the sparks between the two can ignite the gas generated by the storage battery, and furthermore, it has various advantages such as the power source for the light source can be obtained from the storage battery. In the embodiment shown in FIG. 6, an optical liquid level detection device A of the present invention is arranged on a storage battery lid 6.

In this embodiment, the light entrance interface 3 of the device A is located at a position slightly higher than the lowest liquid level of the storage battery, so that the shortage of the electrolytic solution 7 can be detected at an early stage. See you again? In the embodiment shown in the figure, the liquid level detection device A' is covered with a porosity member 8 to prevent scum from the separator of the storage battery from adhering to the light transmitting member 2''. Of course, by configuring this, the above-mentioned light shielding effect can be obtained.

Furthermore, the device shown in FIG. 8 allows an optical liquid level detection device A'' to be placed on the storage battery without changing the shape of the storage battery lid 6' from the conventional one, and the device A is attached to the liquid port plug 9 of the storage battery. ″
A lid 10 that can be opened and closed is provided on the liquid stopper 9 so that the liquid level can be detected either during injection or non-injection. The one shown in Fig. 9 is a further improvement of the above-mentioned embodiment, in which the optical liquid level detection device A is moved up and down by opening and closing of the lid 10', and the highest and lowest liquid levels are detected respectively. It was made so that it could be done.

Several embodiments in which the optical liquid level detection device of the present invention is installed in a storage battery have been described above, but other means for measuring the liquid level in a storage battery include installing the device in a liquid injector. Conceivable.

As described above, the present invention is capable of detecting various liquid levels such as the electrolyte level of a storage battery, and has great industrial value.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a main part showing another embodiment of the present invention. Third
, 4 are a vertical cross-sectional view and a vertical cross-sectional side view showing another embodiment of the present invention. FIG. 5 is a diagram showing the current value from the photosensitive element with respect to the liquid level in the embodiment shown in FIGS. 3 and 4. FIGS. 6 and 7 are longitudinal cross-sectional views showing embodiments in which the present invention is installed in a storage battery. FIGS. 8 and 9 are longitudinal sectional views respectively showing the embodiment arranged on the liquid □ stopper. 1...Light source, 2, 2', 2
''...Light transmitting body, 3, 3', 3''a, 3''b, 3 rivers...Light entrance interface, A, A', A'', A...
・Optical liquid level detection device.

Figure 1 Figure 2 Figure 5 Figure 3 Figure 4 Figure 6 Figure 7 Figure 8 Figure 9

Claims (1)

[Scope of Claims] 1. A light transmitting body that is equipped with a light source and a photosensitive element at its base, has a light entrance interface that hangs down to a desired measurement liquid level at its tip, and has tapered side surfaces to form a total reflection surface. An optical liquid level detection device comprising: 2. The optical liquid level detection device according to claim 1, wherein the light transmitting body has a tip angle of 40° or more. 3. The optical liquid level detection device according to claim 1, which has a light transmitting body having a plurality of light entrance interfaces.