JPS5822867B2 - Electrolyte concentration detector for lead-acid batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detector for measuring the electrolyte concentration of a lead-acid battery.

The concentration of the electrolyte in lead-acid batteries is closely related to the battery's condition, and the only way to know the remaining capacity is to measure the concentration.

In order to measure concentration relatively easily, various devices for measuring specific gravity have been invented.

Focusing on the fact that the refractive index of the electrolyte changes with changes in the electrolyte concentration, that is, the specific gravity, we can measure the critical angle between the prism and the electrolyte using a light-concentrating prism and a light receiving element.
This is one method.

Compared to hydrometers that detect changes in the refractive index, changes in the electrolyte level,
It is completely unaffected by vibrations and can achieve extremely high precision.

When light enters a substance with a refractive index N2 (N, 〉N2) from a substance with a refractive index N1, some light is reflected at a reflection angle equal to the incident angle i, and some is refracted at a refraction angle r according to the following equation. do.

That is, NI Sin i −=N2 Sin r
−−−−−−(1) When light enters from an object with a high refractive index to an object with a low refractive index, the angle of refraction is always greater than the angle of incidence, so if the angle of incidence is gradually increased, the angle of refraction may reach 90°. .

This is a phenomenon called total internal reflection, and formula (2) holds true.

NI Sinθ-N2Sin90°-N2...
(2) θ is called the critical angle, and all light with an incident angle greater than θ will be reflected.

In lead-acid batteries, there is a proportional relationship between the sulfuric acid specific gravity value and battery capacity, and when the specific gravity is 1.260 to 1.280, it is fully charged.
A fully discharged state occurs when the specific gravity is 1.100 to 1.150.

Refractive index of sulfuric acid at 20°C and refractive index 1.4032
The critical angle when light enters the sulfuric acid from the prism is shown in the table below.

The specific gravity detector of the present invention utilizes the fact that the refractive index changes depending on the concentration of sulfuric acid as described above, and attempts to detect the specific gravity of sulfuric acid by measuring the critical angle with the prism. The location is as follows.

In other words, it consists of a light source, a slit that limits the radiation angle of the light source, a prism whose bottom surface is in contact with the electrolyte, a row of light-receiving elements, and an electric circuit.The light that comes out of the light source and passes through the slit is reflected at the bottom of the prism. This electrolyte concentration detector for a lead-acid battery is characterized in that the position of each optical component is fixed so as to reach a row of light-receiving elements, and the electrolyte concentration is detected from the number of elements in the row of light-receiving elements that receive light.

FIG. 1 is a schematic diagram of an optical unit of an embodiment of the concentration detector of the present invention.

1 is a point light source, 2 is a slit that limits the angle of light emitted from the light source, 3 is a prism whose bottom surface is in contact with an electrolyte, 4 is sulfuric acid as an electrolyte, and 5 is a row of light receiving elements.

If the incident angle of the light emitted from the point light source 1 and incident on the bottom surface β' of the prism through the slit 2 is exactly the critical angle between the prism and the sulfuric acid at that point, then the light received by the row of light receiving elements is The amount of light received.

It will look like Figure 2.

In the figure, α, β3γ are the light receiving elements in the row 5 of light receiving elements in FIG.
γ receives the reflected light from the γ′ point.

As shown in FIG. 2, the amount of received light increases rapidly from the position β, which is the critical angle.

When the concentration of sulfuric acid changes, the refractive index changes, and the critical angle changes,
The position of the light receiving element where the amount of light received increases rapidly also changes.

FIG. 3 is a block diagram of one embodiment of the present invention.

6 is a lamp as a light source, 7 is a prism, and 8 is sulfuric acid as an electrolyte to be measured.

The light emitted from the light source 6 is reflected at the interface between the prism and the electrolyte and enters the image sensor 9, which is an array of light receiving elements.

The spacing between the light receiving elements of the image sensor is 30 μm and the number of elements is 512.

The image sensor 9 is driven by a clock 10 and controlled by a control circuit 11.

The output is amplified by a video amplifier 12, converted into a binary signal (H level, L level) by a Schmitt trigger 13, and inputted to a control circuit 11.

The control circuit 11 is composed of an 8-bit microprocessor sensor.

The counter 14 counts the number of clocks until the Schmitt trigger 13 becomes H level under the control of the control circuit 11.

15 is a temperature sensing element, 16 is a temperature correction circuit, and the output thereof is also input to the control circuit 11.

17 is a display device that displays the temperature-corrected concentration of the electrolytic solution.

The electrolyte concentration detector for lead-acid batteries of the present invention can measure the concentration without being affected by the agitation or flow of the electrolyte, and can obtain data with extremely high accuracy of 0.001 when converted to specific gravity. Its industrial value is enormous.

Note that this concentration detector can measure not only the concentration of sulfuric acid but also the concentration of other types of liquids in which there is a correlation between concentration and refractive index.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an optical unit of an embodiment of the concentration detector of the present invention. FIG. 2 is a diagram showing changes in the amount of received light due to differences in the position of the light receiving element. FIG. 3 is a block diagram of one embodiment. 1...--Light source, 2...Slit, 3.
...prism, 4...electrolyte, 5...
. . . row of light receiving elements, 9 . . . image sensor which is a row of light receiving elements, 11 . . . control circuit,
17...Display device.

Claims (1)

[Claims] 1. Consisting of a light source, a slit that limits the radiation angle of the light source, a prism whose bottom surface is in contact with an electrolyte, a row of light receiving elements, and an electric circuit, the light emitted from the light source and passed through the slit is ,
The light is reflected on the bottom of the prism and becomes a receiving element. 1. An electrolyte concentration detector for a lead-acid battery, characterized in that the position of each optical component is fixed so as to reach the row of light-receiving elements, and the electrolyte concentration is detected from the number of light-receiving elements in the row.