JPH0633650Y2 - Lead acid battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lead storage battery capable of measuring the specific gravity of an electrolytic solution with a humidity sensor.

2. Description of the Related Art Conventionally, as a method of indirectly estimating the state of charge and life of a lead storage battery, a method of measuring specific gravity has been generally used. For this purpose, a float type hydrometer and an optical hydrometer are used.

Problems to be Solved by the Invention The above-described float type hydrometer or optical hydrometer cannot be inserted into a lead acid battery because the operation is complicated and the size is too large. Can not be measured. Moreover, the specific gravity of a battery with a small amount of liquid could not be measured.

Means for Solving the Problems On the other hand, the inventors of the present application have proposed a small-sized humidity sensor in which a humidity non-permeable fluororesin film or a film in which a water vapor selective permeable layer or an acid vapor absorption layer is formed is covered with a small size. Fast response,
Moreover, we have proposed a solute concentration measurement sensor in aqueous solution that has a long life.

The present invention is characterized in that a humidity sensor for detecting the specific gravity of an electrolytic solution, which is covered with a porous water-impermeable fluororesin film, is attached to the front end portion of a liquid stopper configured so that the front end is immersed in the electrolytic solution. The present invention relates to a lead storage battery.

Action The principle of action of the electrolyte specific gravity sensor used in the lead acid battery of the present invention is a method of detecting the concentration of the electrolyte from the water vapor pressure of the electrolyte. That is, a solute concentration measuring sensor in an aqueous solution obtained by coating a porous water-impermeable fluororesin film that selectively permeates only the water vapor through the humidity sensor or a film having a water vapor selective permeation layer or an acid vapor absorption layer formed on the film. It is to be immersed in the sulfuric acid electrolyte of the lead acid battery and can be understood as a change in the specific gravity and relative humidity of the electrolyte as the battery is charged and discharged.If the relationship between the specific gravity of the sulfuric acid aqueous solution and the relative humidity is obtained in advance. ,
From the relative humidity value, the specific gravity of the sulfuric acid aqueous solution, that is, the battery state can be known. The film has a function of preventing the humidity sensor from coming into direct contact with the electrolytic solution, which is an aqueous solution of sulfuric acid, and a function of forming a water vapor layer.

When such a sensor is a lead-acid battery attached to the tip of a liquid stopper whose tip is immersed in the electrolyte, the specific gravity of the electrolyte can be known at all times, and the sensor can be easily replaced and removed. Can be done.

Examples Hereinafter, the present invention will be described using preferred examples.

First, a water vapor repellent layer having a thickness of 0.1 mm and a porosity of 75% is coated on one side with an alcohol solution of a perfluorocarbon sulfonic acid resin to form a water vapor selective permeable layer. Next, an acid vapor absorption layer obtained by binding fine powder of calcium carbonate with a binder is formed on the water vapor selective permeable layer to form a triple layer structure film.

Next, a humidity sensor of a type in which a moisture sensitive film made of a polymer electrolyte is formed on an alumina substrate is attached to a liquid stopper, and the humidity sensor is covered with the above three-layer structure film. FIG. 1 shows a liquid plug provided with the electrolyte specific gravity sensor thus obtained, and FIG. 2 shows a cross-sectional structure of its tip. In FIGS. 1 and 2, the humidity sensor 1 is incorporated in the liquid stopper 2, and the triple-layered structure film 3 is attached thereto by the O-ring 4.

The humidity sensor used for the electrolyte specific gravity sensor is detected by the method of detecting the impedance when an alternating current of 1 KHz is applied and detecting the impedance change as a voltage change.

FIG. 3 shows a diagram when a liquid plug equipped with the electrolyte specific gravity sensor is attached to a lead storage battery. With the liquid stopper fixed to the battery 7, the tip of the sensor is always immersed in the electrolytic solution 5. Reference numeral 6 denotes a detection unit that converts the relative humidity signal detected by the sensor into the electrolytic solution specific gravity.

Next, the electrolytic solution specific gravity converted from the output value of the sensor when the lead storage battery was discharged at a rate of 5 hours was compared with the electrolytic solution specific gravity value theoretically estimated from the discharge amount and the specific gravity value obtained from a float hydrometer. A comparison is shown in FIG. Compared with the theoretical transition 11 of the electrolyte specific gravity, the transition 12 of the sensor responded fairly well with a slight response delay. Moreover, it was almost in agreement with the transition 13 of the specific gravity obtained from the float hydrometer.

Next, FIG. 5 shows the results of a temperature accelerated life test conducted to confirm the durability of the humidity sensor mounted on the lead storage battery. The temperature was 80 ℃ and 60 ℃. From this result, it was found that the life at 25 ° C was estimated to be about 7 years, and the sensor according to the present invention can be sufficiently put to practical use.

If the sensor has reached the end of its useful life, the entire liquid stopper may be replaced.

Effects of the Invention As described above, the lead acid battery according to the present invention can be easily installed and replaced with the electrolyte specific gravity sensor and can measure the specific gravity quickly and continuously, and its industrial value is extremely large. is there.

[Brief description of drawings]

FIG. 1 is a view showing the structure of a liquid plug equipped with an electrolyte solution specific gravity sensor used in the lead storage battery of the present invention, and FIG. 2 is a sectional structure view of its tip. FIG. 3 is a diagram in which a liquid stopper equipped with a sensor is attached to a battery. FIG. 4 is a diagram showing the transition of the specific gravity value of the sensor during discharging, and FIG. 5 is a diagram showing the relationship between the temperature and the service life of the sensor. 1 ... Humidity sensor, 2 ... Liquid plug 3 ... Trilayer coating layer, 4 ... O-ring 5 ... Electrolyte, 6 ... Detection unit 7 ... Lead battery

Claims (1)

[Scope of utility model registration request] 1. A humidity sensor for detecting the specific gravity of an electrolytic solution, which is covered with a porous water-impermeable fluororesin film, is attached to the front end of a liquid stopper configured to be immersed in the electrolytic solution. Characteristic lead acid battery.