JPH06333606A - Capacity sensor for lead-acid battery - Google Patents

Abstract

PURPOSE:To make possible the specific gravity of a sulfuric acid solution to be measured at any time even in a position apart from a lead-acid battery in order to obtain a residual capacity, and detect a water supply timing simultaneously. CONSTITUTION:A battery jar 12 contains therein first electrodes 22a, 22b facing each other with such an interval k1 as to generate capillarity, second electrodes 23a, 23b facing each other with an interval k2 larger than the interval k1, and third electrodes 27a, 27b kept to be brought into entire contact with a sulfuric acid solution. Heights of liquid levels 131, 132 of each pair of the electrodes are obtained by measuring resistance values. Moreover, the specific gravity is calculated on the basis of the difference in height.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacity sensor used for measuring the remaining capacity of lead acid batteries.

[0002]

2. Description of the Related Art A sulfuric acid aqueous solution, which is an electrolytic solution of a lead storage battery, continues to be discharged, so that the sulfuric acid concentration decreases and the specific gravity decreases. Therefore, the remaining capacity of the lead acid battery can be obtained by measuring the specific gravity of the sulfuric acid aqueous solution, and the float 1 as shown in FIG.
1 was used.

[0003]

The conventional measurement of the specific gravity of the sulfuric acid aqueous solution by the float 11 is carried out by floating the float 11 on the sulfuric acid aqueous solution 13 in the battery case 12 every time the measurement is made. The work is troublesome and cannot always be measured, and the measurement cannot be performed if the battery is apart from the lead storage battery, for example.

On the other hand, in a lead storage battery, since water evaporates and the amount of sulfuric acid aqueous solution is reduced by repeating charging and discharging, it is necessary to replenish the water, that is, the above-mentioned residual capacity and this replenishment water when using the lead storage battery. Although it is important to detect the time of day, the float 11 that has been used conventionally measures only the specific gravity and cannot detect the time of rehydration.

The object of the present invention is to eliminate the conventional drawbacks and to always measure the specific gravity of a sulfuric acid aqueous solution for determining the remaining capacity of a lead storage battery without disposing a measuring instrument in each battery case. Another object of the present invention is to provide a capacity sensor capable of measuring the lead-acid battery from a position remote from the lead-acid battery and detecting the refueling time at the same time.

[0006]

According to the present invention, in a lead-acid battery battery case, a plate surface is arranged in a vertical direction, and a pair of first electrodes opposed to each other with an interval enough to cause a capillary phenomenon, and the plate surface is arranged in a vertical direction. And a pair of second electrodes facing each other with a spacing larger than the spacing of the first electrodes, and a pair of second electrodes that are always in contact with the electrolytic solution regardless of fluctuations in the liquid level of the electrolytic solution in the battery case. Three electrodes are provided.

That is, the present invention utilizes the capillary phenomenon for measuring the specific gravity of the sulfuric acid aqueous solution for determining the remaining capacity of the lead storage battery. The substance has an inherent surface tension,
The aqueous solution of sulfuric acid, which is the electrolytic solution of the lead storage battery, also has different surface tension and different specific gravity due to the difference in concentration. Now, assuming that the surface tension of the aqueous sulfuric acid solution is σ, the density is d, and the liquid level height increased by capillary action between a pair of plate surfaces facing each other at an interval k is h, the relationship between them is expressed by the equation (1). be able to.

2σ / dg = hk {1 + 0.1037 (k / h) -0.052 (k / h) ² } (1) where g: gravity acceleration For example, when the sulfuric acid concentration decreases, the surface tension σ increases,
Since the specific gravity is small, it can be seen from equation (1) that the liquid level height h is large. Since the specific gravity and the liquid level height h have a correlation, the specific gravity at that time can be obtained if the liquid level height h is known.

[0009]

In the present invention configured as described above, the resistivity of the sulfuric acid aqueous solution can be obtained by measuring the resistance value between the pair of third electrodes. The resistance values between the first electrodes and between the second electrodes change corresponding to the liquid surface height of the sulfuric acid aqueous solution between the electrodes. Therefore, if the resistance values between the first electrodes and between the second electrodes are measured, the liquid level between the electrodes can be determined from the resistance values and the resistivity of the sulfuric acid aqueous solution previously obtained. The specific gravity is obtained from the difference between the two liquid levels, and the normal liquid level in the battery case at that time is obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1A shows an outline of a capacity sensor 21 according to the present invention arranged in a battery case 12 of a lead storage battery, and details thereof are shown in FIGS. 1B and 2. The plate surface is in the vertical direction, and the pair of first electrodes 22a, 22b opposed to each other with an interval k _{1 such} that a capillary phenomenon occurs, and similarly, the plate surface is in the vertical direction and the distance k between the first electrodes 22a, 22b A pair of second electrodes 23a and 23b facing each other with a spacing k ₂ larger than ₁ are provided in the battery case 12 of the lead storage battery, and their lower portions are dipped in the sulfuric acid aqueous solution 13.

In this example, these first electrodes 22a, 22b
The second electrodes 23a and 23b are rectangular plate-shaped insulating plates 2 in which plate surfaces in the vertical direction are arranged in a row so as to face each other.
The structure is formed on the surfaces of the opposing plates 4, 25, and 26, that is, the first electrode 22a is uniformly formed on one surface of the insulating plate 24 in the up-down direction, and the insulation facing the insulating film 24 is formed. Board 2
Similarly, the first electrode 22b is formed on the plate surface of the insulating plate 2
Second electrodes 23a and 23b are formed on the other plate surface of No. 5 and the plate surface of the insulating plate 26 facing the other plate surface. The interval k ₁ is, for example, about 1 mm, and the interval k ₂ is, for example, about several times the interval k ₁ .

The surface of the sulfuric acid aqueous solution 13 is the first electrode 2
2a, 22b and between the second electrodes 23a, 23b rise by capillarity, respectively, and the liquid levels 13 ₁ and 13
Form ₂ . The interval k ₂ may be an interval at which substantial capillarity does not occur. Further, a pair of third electrodes 27a and 27b, which are always in contact with the sulfuric acid aqueous solution 13 irrespective of fluctuations in the liquid level of the sulfuric acid aqueous solution 13 in the battery case 12, are provided in the battery case 12. Therefore, in this example, the insulating plate 2
Insulating plate 28 facing each other plate surface of No. 4 is provided, and electrodes 29a, 29b are provided on the facing plate surfaces of these insulating plates 24, 28.
Of the insulators 31a, 3
As a structure for covering each with 1b, exposed portions of the electrodes 29a, 29b are used as third electrodes 27a, 27b, and the third electrodes 27a, 27b are constantly immersed in the sulfuric acid aqueous solution 13. That is, the liquid surface 13 _S between the third electrodes 27a and 27b is always located on the insulators 31a and 31b. The facing distance k _S between the third electrodes 27a and 27b is substantially equal to the distance k _{1 in} this example.

The insulating plates 24, 25, 26 and 28 are, for example,
A lath plate is used, and each electrode is formed of gold, for example. Up
In the capacitance sensor 21 configured as described above, the liquid level 1
Three₁, 13₂Corresponding to the height of each, that is, sulfuric acid water
The solution 13 is the first electrode 22a, 22b and the second electrode 23.
a, 23b corresponding to the area of contact with the first electrode 22a,
Resistance value between 22b R ₁And between the second electrodes 23a and 23b
Resistance value R₂Changes. Therefore, the liquid level 13₁, 13₂of
The height is the resistance value R₁, R₂Can be detected by
it can. Also, the resistance value R between the third electrodes 27a and 27b_S
Changes in accordance with the change in resistivity of the sulfuric acid aqueous solution 13.

Next, a method of detecting the specific gravity of the sulfuric acid aqueous solution 13 and its water replenishment timing by using the capacity sensor 21 will be described. The resistance value of the sulfuric acid aqueous solution between the electrodes is obtained by the following formula. Resistance value (Ω) = length (cm) · resistivity (Ω · cm) / area (cm ² ) Now, as shown in FIG. 1B, the sulfuric acid aqueous solution 13 in the battery case 12
The heights of the liquid surfaces 13 ₁ and 13 ₂ from the normal liquid surface 13 ₀ and the lower ends of the insulators 31a and 31b are h ₁ , h ₂ and h _s , respectively, and the length of each electrode immersed in the sulfuric acid aqueous solution 13. H
₀ , the width of each electrode is W, and the resistivity of the sulfuric acid aqueous solution 13 is ρ
Then, between the first electrodes 22a and 22b, the second electrode 23
Resistance value R between a and 23b and between the third electrodes 27a and 27b
₁ , R ₂ and R _S are each represented by the following equation.

R ₁ = k ₁ · ρ / W (h ₀ + h ₁ ) R ₂ = k ₂ · ρ / W (h ₀ + h ₂ ) R _S = k _S · ρ / W (h ₀ + h _S ) 3rd The electrodes 27a and 27b always have their entire area W (h ₀ + h
_{Since S} ) is in contact with the sulfuric acid aqueous solution 13, the resistivity ρ can be obtained by measuring R _S. The resistivity ρ changes as the concentration of the sulfuric acid aqueous solution 13 changes due to charging and discharging.

By measuring R ₁ and R ₂ , (h ₀
+ H ₁ ) and (h ₀ + h ₂ ) are obtained. The liquid level height increased by the capillary phenomenon and the inter-electrode spacing have the relationship shown in FIG. 3A. When the spacing k is small, the above equation (1) is used.
{0.1037 (k / h) -0.052 (k /
Since h) ² } has an extremely small value, the following approximate expression can be obtained.

2σ / dg = hk {1 + 0.1037 (k / h) -0.052 (k / h) ² } ≈hk (2) where 2σ / dg is X, X≈hk, h = It is expressed as X / k, and the relations h ₁ = X / k ₁ and h ₂ = X / k ₂ are obtained.

(H ₀ + h) obtained by measuring R ₁ and R _{2.
1), (h 0 + h} 2) , respectively A, when put is B, by using the _{h 1, h 2, A =} h 0 + (X / k 1) ... (3) B = h 0 + (X / K ₂ ) When these differences are taken, AB = (X / k ₁ ) − (X / k ₂ ) = X (k ₂ −k ₁ ) / k ₁ k ₂ ∴ X = (AB) Since k ₁ k ₂ / (k ₂ −k ₁ ) A, B, k ₁ and k ₂ are known values, X is obtained, and this X is substituted into equation (3) to obtain h ₀ .

Since h ₀ = A- (X / k ₁ ) h ₀ is obtained, the height of the sulfuric acid aqueous solution 13 increased by the capillary phenomenon at h _{1, that} is, the interval k ₁ , is obtained. Since the specific gravity has a predetermined relationship as shown in FIG. 3B from the above-mentioned formula (1), the specific gravity of the sulfuric acid aqueous solution 13 at that time can be obtained. There is a relationship between the specific gravity of the sulfuric acid aqueous solution 13 and the electromotive force of the lead storage battery as shown in FIG. 3C, and the remaining capacity can be obtained from the specific gravity.

On the other hand, h ₀ is a normal liquid level 13 in the battery case 12.
To represent the height of ₀ , for example, the liquid level height h that requires replenishing water
Set _L, and the by comparing the h _L and h _0, it is possible to detect the rehydration time. As shown in FIG. 1A, a temperature sensor 32 is provided together with the capacitance sensor 21, the liquid temperature of the sulfuric acid aqueous solution 13 is measured, and the obtained specific gravity is temperature-corrected, so that a more accurate specific gravity can be obtained. The remaining capacity can be calculated more accurately.

FIG. 4 shows a preferred mounting example of the capacitance sensor 21 according to the present invention. As shown in FIG. 4A, a lead storage battery 33 mounted on a passenger car or the like is provided with (+) electrodes 34 and (−) electrodes 35 on the upper surface thereof, and further has a plurality of water replenishment ports 36, which are respectively caps. It is covered by 37. In this example, the cap 37
As shown in FIG. 4B, the capacitance sensor 21 and the temperature sensor 3
2 is attached, and the cap sensor 37 is screwed into the water replenishing port 36, whereby the capacity sensor 21 and the temperature sensor 3
The lower part of 2 is immersed in a sulfuric acid aqueous solution.

The capacitance sensor 21 and the temperature sensor 32 are connected to a circuit portion (not shown) by a lead wire 38. The circuit unit is configured to measure, for example, the resistance value of the capacitance sensor 21, measure the liquid temperature by the temperature sensor 32, and perform a comparison calculation of the measured values. If the meter displays the remaining capacity and the replenishment time detected by the circuit, and the meter is installed on the instrument panel of the driver's seat of a passenger car, for example, the driver does not need any trouble and the lead-acid battery status is always maintained. You can know.

[0023]

As described above, according to the present invention, a pair of first electrodes opposed to each other with a gap enough to cause a capillary phenomenon, a pair of second electrodes opposed to each other with a gap larger than the gap, and the entire structure are always provided. By providing a pair of third electrodes in contact with the electrolytic solution in the battery case, that is, the sulfuric acid aqueous solution, in the lead acid battery battery case, the resistivity of the sulfuric acid aqueous solution is obtained from the resistance value between the third electrodes, and the resistivity From the resistance values between the first electrodes and between the second electrodes, the liquid surface height of the sulfuric acid aqueous solution between the electrodes is obtained, and the specific gravity of the sulfuric acid aqueous solution is calculated from the difference between the two liquid surface heights. The remaining capacity of the storage battery can be calculated.

Therefore, according to the capacity sensor according to the present invention arranged in the battery case, the remaining capacity of the lead storage battery can be always obtained without any trouble, and at that time from the difference in the measured liquid level height. Since the normal liquid level of the battery case is required, it is possible to detect the replenishment time at the same time, and it is possible to separate from the lead storage battery by providing the required wiring because it is based on electrical detection such as resistance measurement. It is possible to detect the state of the lead storage battery even at the open position.

When a lead storage battery is placed in a vibrating environment, such as a lead storage battery mounted on a passenger car,
In the conventional measurement using a float, the float was shaken by the vibration, and it was impossible to accurately measure the specific gravity of the sulfuric acid aqueous solution. However, according to the capacitance sensor of the present invention, for example, by setting the distance between the second electrodes to be such that a capillary phenomenon that is weaker than that between the first electrodes occurs, the liquid levels between the first and second electrodes are both The liquid level rises due to the capillary phenomenon, that is, because it is within a narrow interval, it does not shake even in a vibrating environment, and therefore, even when the lead storage battery is placed in a vibrating environment, the specific gravity can be accurately determined, that is, The remaining capacity can be accurately determined.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of a capacitance sensor according to the present invention, A is a schematic view thereof, and B is a detailed sectional view.

FIG. 2 is a perspective view showing an embodiment of a capacitance sensor according to the present invention.

FIG. 3 is a diagram for explaining a measuring method using a capacitive sensor according to the present invention, A is a relationship between an electrode interval and a height raised by a capillary phenomenon, B is a relationship between the height and a specific gravity,
C represents the relationship between specific gravity and electromotive force.

4A is a perspective view showing an example of a lead storage battery, and FIG. 4B is a front view showing a state in which the cap of the present invention is attached to the cap.

FIG. 5 is a schematic view showing a float used for conventional measurement of specific gravity.

[Explanation of symbols]

 12 Battery Case 13 Sulfuric Acid Aqueous Solution 21 Capacitance Sensor 22a, 22b First Electrode 23a, 23b Second Electrode 27a, 27b Third Electrode

Claims (1)

[Claims] 1. A pair of first electrodes, which are provided in a lead storage battery battery case and have plate surfaces in an up-down direction and are opposed to each other with an interval such that a capillary phenomenon occurs, and are provided in the lead storage battery battery container. The plate surface is in the vertical direction, the pair of second electrodes facing each other with a gap larger than the gap between the first electrodes, and the lead storage battery provided in the battery case, and the liquid level fluctuation of the electrolyte solution in the battery case. Regardless of the above, a lead-acid battery capacity sensor comprising: a pair of third electrodes that are always in contact with the electrolyte solution.