【０００１】
【発明の属する技術分野】
本発明は制御弁式鉛蓄電池に関する。
【０００２】
【従来の技術】
制御弁式鉛蓄電池は無漏液・無保守の特性を有していることが特徴である。無漏液とは、電解液がセパレータのみに含浸・保持され流動電解液の存在しない構造で、蓄電池を横置きにしても電解液の液漏れがないものをいう。また、無保守とは、前記蓄電池の特徴である密閉反応機能により充電時においてもガスが発生せず、電解液の減少がほとんどなく補液といった保守が不必要な特性をいう。
【０００３】
以上のような優れた特性を有していることから、近年、制御弁式鉛蓄電池は多方面にその用途が拡大している。それに伴って、高信頼性、高エネルギー密度化、長寿命化の要求が強くなってきている。
【０００４】
信頼性に関する問題の一つに該蓄電池に装着されている制御弁があげられる。
【０００５】
制御弁式鉛蓄電池の特徴である密閉反応機能は下記の（１）および（２）式で示される。
【０００６】
上式に示すように正極で失われた水（Ｈ２Ｏ）が負極で再生され、全体として電解液の一部を構成している水が失われることはない。しかし、この反応は外部から酸素（Ｏ２）が浸入すると、上記反応式の再生サイクルが阻害されるので蓄電池内に空気が浸入しないようにする必要がある。しかし、完全密閉にすると、充電条件によってはガスが発生するので内圧が上昇し電槽が破裂することがある。そのため通常、外部からの空気の侵入を阻止し、蓄電池内の圧力が上昇すれば開弁する、いわゆる制御弁（安全弁）が弁座あるいは注液口に装着されている。
【０００７】
前記制御弁の開弁圧は、１５〜３０ｋＰａの範囲に保つ必要がある。開弁圧が上記より高い場合には、蓄電池内の圧力が高くなり、樹脂製の電槽がその圧力に耐えられず膨張することがある。また、開弁圧が上記より低いと、過充電の際に発生した水素ガスおよび酸素ガスが容易に放出されるために電解液の減少を招き、電解液が枯渇状態になり、容量の減少、さらには短寿命の原因になる問題を抱えている。
【０００８】
図１は制御弁式鉛蓄電池に広く使用されている椀式（キャップ式、以降キャップ式という）弁の一例を示す要部断面図で、１はキャップ式弁本体、２は該弁のスカート部、３は該弁の天面、４は弁座、５は電槽の上蓋をそれぞれ示す。該上蓋５は、蓄電池内のガス圧上昇によってキャップ式弁が上昇し、弁座から外れるのを防止する機能を有している。
【０００９】
本願の発明者は、天面３の上面と上蓋５の下面との間隔ａ、弁の天面３の厚みｂおよびスカート部２の長さｃがキャップ式弁の開弁圧を変動させる要因であることに着目し、ａ、ｂおよびｃの関係を一定に保つことによって、適切な開弁圧を維持できることを見出した。本発明はその知見に基づくものである。
【００１０】
【発明が解決しようとする課題】
本発明が解決しようとする課題は、キャップ式弁を装着した制御弁式鉛蓄電池において、適切な開弁圧が維持され、過充電状態においても電槽の膨れや電解液の過剰な減少がなく、安定した性能を有する制御弁式鉛蓄電池を提供することにある。
【００１１】
【課題を解決するための手段】
課題を解決するための手段として、請求項１によれば、椀式（キャップ式）弁を備えた制御弁式鉛蓄電池において、
前記弁の天面の上面と電槽の上蓋下面との間隔をａ（ｍｍ）、前記弁の天面の肉厚をｂ（ｍｍ）、前記弁のスカート部の長さをｃ（ｍｍ）とした時に、
１＜（ｂ＋ｃ）／ａ≦１．４であることを特徴とするものである。
【００１２】
本願の発明者は、前記弁の天面の上面と電槽の上蓋下面との間隔をａ、弁の天面の肉厚ｂおよび弁のスカート部の長さｃが弁の開弁圧を変動させる要因であることを見出し、これらの長さを変えた弁あるいは蓄電池を試作し、それらを試験した結果、上記関係式を満たす制御弁式鉛蓄電池であれば上述した１５〜３０ｋＰａの範囲の適切な開弁圧が得られることがわかった。
【００１３】
【発明の実施の形態】
本発明の実施の形態は、キャップ式弁を備えた制御弁式鉛蓄電池において、前記弁の天面の上面と電槽の上蓋下面との間隔をａ（ｍｍ）、前記弁の天面の肉厚をｂ（ｍｍ）、前記弁のスカート部の長さをｃ（ｍｍ）とした時に、
１＜（ｂ＋ｃ）／ａ≦１．４
とすることによって、適切な開弁圧が得られるとするもので、以下に実施例により具体的に示す。
【００１４】
【実施例】
（実施例１）
正・負極板を繊維径、１μ以下の極細ガラス繊維から成るセパレータを介して積層した極板群（エレメント）を用いた一般的な定格容量７Ａｈの制御弁式鉛蓄電池の弁座に、天面の厚みｂを１．５ｍｍ、該弁のスカート部の長さｃを５ｍｍとしたキャップ式弁を装着し、前記弁の天面の上面と電槽の上蓋下面との間隔ａ（ｍｍ）を変え、（ｂ＋ｃ）／ａの値の異なる７種類の制御弁式鉛蓄電池を各３個作製した。その内容を表１に示す。
【００１５】
【表１】
【００１６】
上記蓄電池に圧力センサーを取り付け、明らかにガスが発生する充電条件、すなわち、０．２ＣＡ（Ｃ：定格容量、Ａ：電流の単位）の電流で充電を行い、前記弁の開弁圧を測定した。その結果を図２に示す。
【００１７】
図２に示すように、（ｂ＋ｃ）／ａと開弁圧との関係を求めた結果、本発明の１＜（ｂ＋ｃ）／ａ≦１．４を満足するＮｏ．３〜Ｎｏ．６の蓄電池では、開弁圧が１８ｋＰａから２５ｋＰａの範囲にあり、適切な開弁圧を示した。この範囲の開弁圧であれば、０．２ＣＡのような大きな電流で充電しても、電槽が膨れるといったこともなく、また、水素ガスおよび酸素ガスが過剰に排出されることもなく制御弁式鉛蓄電池として安定した性能を維持できる。しかし、（ｂ＋ｃ）／ａが１以下になると開弁圧が低く、またばらつきも大きくなり、電解液の減少による蓄電池の重量減少が見られ、この状態を続けると容量が低下する。一方、（ｂ＋ｃ）／ａが１．４より大きくなると急激に開弁圧が高くなり、蓄電池の内圧が上昇し、電槽の膨張の兆候がみられた。
（実施例２）
実施例２では、キャップ式弁の天面の上面と電槽の上蓋下面との間隔ａを５ｍｍ、スカート部の長さｃを４ｍｍと固定して、該弁の天面ｂの厚みを変えた弁を試作した。その内容を表２に示す。これら弁を実施例１と同様の制御弁式鉛蓄電池に装着し、同じ試験条件で弁の開弁圧を測定した。その結果を図３に示す。
【００１８】
【表２】
【００１９】
図３に示すように、弁の天面の厚みを変えた場合にも、本発明の１＜（ｂ＋ｃ）／ａ≦１．４の関係を満足しているＮｏ．１０〜１２の蓄電池の開弁圧は２０〜２５ｋＰａの適切な範囲にあった。（ｂ＋ｃ）／ａが１以下と本発明の条件を逸脱したＮｏ．８およびＮｏ．９の蓄電池は開弁圧が低かった。また、天面の厚みｂが３．５ｍｍと厚いＮｏ．１３の蓄電池は開弁圧が５０ｋＰａと高く、実施例１と同じ傾向が得られた。
（実施例３）
実施例３では、キャップ式弁の天面の上面と電槽の上蓋下面との間隔ａを５ｍｍ、該弁の天面の厚みｂを１．５ｍｍと固定して、スカート部の長さｃを変えた弁を試作した。その内容を表３に示す。これら弁を実施例１と同様の制御弁式鉛蓄電池に装着し、同じ試験条件で弁の開弁圧を測定した。その結果を図４に示す。
【００２０】
【表３】
【００２１】
図４に示すように、スカート部の長さｃを変えて、（ｂ＋ｃ）／ａを変動させた場合も、（ｂ＋ｃ）／ａが１以下のＮｏ．１４およびＮｏ．１５の蓄電池は開弁圧が低く、ｃが６ｍｍと長く、（ｂ＋ｃ）／ａが１．５であるＮｏ．１８の蓄電池は弁圧が高かった。これに対して、１＜（ｂ＋ｃ）／ａ≦１．４の範囲のＮｏ．１０、１６、１７は、２０〜２５ｋＰａと適切な開弁圧を示した。
【００２２】
以上の結果から、前記弁の天面の上面と電槽の上蓋下面との間隔をａ（ｍｍ）、前記弁の天面の肉厚をｂ（ｍｍ）、前記弁のスカート部の長さをｃ（ｍｍ）を適宜変動させても、３者の関係が１＜（ｂ＋ｃ）／ａ≦１．４の関係を満足しておれば、ガスが明らかに発生するような大きな電流で充電しても、蓄電池の内圧が高くなりすぎて電槽が膨れたり、開弁圧が低すぎてガスが多量に放出され電解液が減少し容量が低下するといったことがなく、制御弁式鉛蓄電池を安全にまた、安定して作動できることが分かった。
【００２３】
【発明の効果】
制御弁式鉛蓄電池において、弁の形状や装着条件によっては、ガスが発生するような大きな電流で充電した場合に、電槽が膨れたり、ガスの排出が多く、電解液の枯渇状態を招き容量低下するといった好ましくない状態が起ることがあったが、本発明によれば、前記蓄電池に装着されているキャップ式弁の天面の上面と電槽の上蓋下面との間隔をａ（ｍｍ）、前記弁の天面の肉厚をｂ（ｍｍ）、前記弁のスカート部の長さをｃ（ｍｍ）とした時に、
１＜（ｂ＋ｃ）／ａ≦１．４の関係を維持することによって、前記制御弁が適切な範囲内の圧力で開弁し、性能の安定した制御弁式鉛蓄電池が得られ、その工業的効果が極めて大である。
【図面の簡単な説明】
【図１】椀式（キャップ式）弁を弁座に装着した状態を示す要部断面図。
【図２】（ｂ＋ｃ）／ａと開弁圧との関係を示す図（ｂおよびｃを固定）。
【図３】（ｂ＋ｃ）／ａと開弁圧との関係を示す図（ａおよびｃを固定）。
【図４】（ｂ＋ｃ）／ａと開弁圧との関係を示す図（ａおよびｂを固定）。
【符号の説明】
１ キャップ式弁本体
２ 弁のスカート部
３ 弁の天面
４ 弁座
５ 上蓋[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control valve type lead storage battery.
[0002]
[Prior art]
Control valve type lead-acid batteries are characterized by having the characteristics of no leakage and no maintenance. The non-leakage liquid has a structure in which the electrolyte is impregnated and held only in the separator and has no flowing electrolyte, and has no electrolyte leakage even when the storage battery is placed horizontally. The term "no maintenance" refers to a characteristic in which no gas is generated even during charging due to the sealed reaction function which is a feature of the storage battery, the electrolyte is hardly reduced, and maintenance such as replacement is unnecessary.
[0003]
Because of these excellent characteristics, the use of control valve type lead-acid batteries has been expanding in various fields in recent years. Accordingly, demands for high reliability, high energy density, and long life have been increasing.
[0004]
One of the reliability problems is a control valve mounted on the storage battery.
[0005]
The closed reaction function which is a feature of the control valve type lead-acid battery is represented by the following equations (1) and (2).
[0006]
[0007]
The valve opening pressure of the control valve needs to be kept in the range of 15 to 30 kPa. If the valve opening pressure is higher than the above, the pressure in the storage battery becomes high, and the resin container may not be able to withstand the pressure and may expand. Further, if the valve opening pressure is lower than the above, the hydrogen gas and oxygen gas generated at the time of overcharging are easily released, causing a decrease in the electrolyte, the electrolyte being depleted, and a decrease in capacity, Furthermore, there is a problem that causes a short life.
[0008]
FIG. 1 is a sectional view of an essential part showing an example of a bowl-type (cap-type, hereinafter referred to as cap-type) valve widely used in a control valve type lead-acid battery, wherein 1 is a cap-type valve main body, and 2 is a skirt portion of the valve. 3, a top surface of the valve; 4, a valve seat; and 5, an upper lid of the battery case. The upper lid 5 has a function of preventing the cap-type valve from rising due to a rise in gas pressure in the storage battery and coming off the valve seat.
[0009]
The inventor of the present application believes that the distance a between the upper surface of the top surface 3 and the lower surface of the upper lid 5, the thickness b of the top surface 3 of the valve, and the length c of the skirt portion 2 cause the valve opening pressure of the cap-type valve to fluctuate. Focusing on a certain point, it has been found that an appropriate valve opening pressure can be maintained by keeping the relationship between a, b and c constant. The present invention is based on that finding.
[0010]
[Problems to be solved by the invention]
The problem to be solved by the present invention is that, in a control valve type lead storage battery equipped with a cap type valve, an appropriate valve opening pressure is maintained, and even in an overcharged state, there is no swelling of the battery case or excessive decrease of the electrolyte. Another object of the present invention is to provide a control valve type lead storage battery having stable performance.
[0011]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a control valve type lead storage battery including a bowl-type (cap-type) valve.
The distance between the upper surface of the top surface of the valve and the lower surface of the top lid of the battery case is a (mm), the thickness of the top surface of the valve is b (mm), and the length of the skirt portion of the valve is c (mm). When you do
1 <(b + c) /a≦1.4.
[0012]
The inventor of the present application has determined that the distance a between the top surface of the top surface of the valve and the bottom surface of the top lid of the battery case, the thickness b of the top surface of the valve, and the length c of the skirt portion of the valve fluctuate the valve opening pressure of the valve. As a result, they found that the valve or storage battery with a different length was tested and tested. As a result, if it is a control valve type lead-acid battery that satisfies the above-mentioned relational expression, an appropriate value in the range of 15 to 30 kPa described above is obtained. It was found that a suitable valve opening pressure could be obtained.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention relates to a control valve type lead-acid battery having a cap-type valve, wherein the distance between the upper surface of the top surface of the valve and the lower surface of the top lid of the battery case is a (mm), and the thickness of the top surface of the valve is When the thickness is b (mm) and the length of the skirt portion of the valve is c (mm),
1 <(b + c) /a≦1.4
By doing so, it is assumed that an appropriate valve opening pressure can be obtained.
[0014]
【Example】
(Example 1)
The valve seat of a control valve type lead-acid battery with a rated capacity of 7 Ah using a plate group (element) in which positive and negative plates are laminated via a separator made of ultrafine glass fibers having a fiber diameter of 1 μ or less, A cap-type valve with a thickness b of 1.5 mm and a length c of the skirt portion of the valve of 5 mm was attached, and the distance a (mm) between the upper surface of the top surface of the valve and the lower surface of the upper lid of the battery case was changed. , Three types of control valve type lead-acid batteries having different values of (b + c) / a were manufactured. The contents are shown in Table 1.
[0015]
[Table 1]
[0016]
A pressure sensor was attached to the storage battery, charging was performed under a charging condition that clearly generates gas, that is, a current of 0.2 CA (C: rated capacity, A: unit of current), and the valve opening pressure of the valve was measured. . The result is shown in FIG.
[0017]
As shown in FIG. 2, as a result of obtaining the relationship between (b + c) / a and the valve opening pressure, No. 1 satisfying 1 <(b + c) /a≦1.4 of the present invention. 3-No. In the storage battery of No. 6, the valve opening pressure was in the range of 18 kPa to 25 kPa, indicating an appropriate valve opening pressure. When the valve opening pressure is in this range, even if the battery is charged with a large current such as 0.2 CA, the battery case does not expand and the hydrogen gas and the oxygen gas are not excessively discharged. Stable performance can be maintained as a valve-type lead storage battery. However, when (b + c) / a is 1 or less, the valve opening pressure is low and the variation is large, and the weight of the storage battery is reduced due to the decrease in the electrolyte. If this state is continued, the capacity is reduced. On the other hand, when (b + c) / a was greater than 1.4, the valve opening pressure rapidly increased, the internal pressure of the storage battery increased, and signs of expansion of the battery case were observed.
(Example 2)
In Example 2, the gap a between the upper surface of the top surface of the cap-type valve and the lower surface of the top lid of the battery case was fixed at 5 mm, and the length c of the skirt portion was fixed at 4 mm, and the thickness of the top surface b of the valve was changed. A prototype valve was made. The contents are shown in Table 2. These valves were mounted on a control valve type lead-acid battery as in Example 1, and the valve opening pressure of the valves was measured under the same test conditions. The result is shown in FIG.
[0018]
[Table 2]
[0019]
As shown in FIG. 3, even when the thickness of the top surface of the valve is changed, No. 1 satisfying the relationship of 1 <(b + c) /a≦1.4 of the present invention. The valve opening pressures of the 10-12 storage batteries were in the appropriate range of 20-25 kPa. (B + c) / a is 1 or less, which deviates from the conditions of the present invention. 8 and no. Battery No. 9 had a low valve opening pressure. In addition, the thickness b of the top surface is 3.5 mm, which is thick. The storage battery of No. 13 had a high valve opening pressure of 50 kPa, and the same tendency as in Example 1 was obtained.
(Example 3)
In Example 3, the distance a between the upper surface of the top surface of the cap-type valve and the lower surface of the upper lid of the battery case was fixed at 5 mm, the thickness b of the top surface of the valve was fixed at 1.5 mm, and the length c of the skirt portion was reduced. A prototype of the changed valve was made. Table 3 shows the details. These valves were mounted on a control valve type lead-acid battery as in Example 1, and the valve opening pressure of the valves was measured under the same test conditions. The result is shown in FIG.
[0020]
[Table 3]
[0021]
As shown in FIG. 4, when (b + c) / a is varied by changing the length c of the skirt portion, No. 1 in which (b + c) / a is 1 or less is obtained. 14 and No. The storage battery of No. 15 has a low valve opening pressure, c is as long as 6 mm, and (b + c) / a is 1.5. The storage battery of No. 18 had a high valve pressure. On the other hand, No. 1 in the range of 1 <(b + c) /a≦1.4. 10, 16, and 17 showed an appropriate valve opening pressure of 20 to 25 kPa.
[0022]
From the above results, the distance between the upper surface of the top surface of the valve and the lower surface of the top lid of the battery case is a (mm), the thickness of the top surface of the valve is b (mm), and the length of the skirt portion of the valve is Even if c (mm) is appropriately changed, if the relationship of the three satisfies the relationship of 1 <(b + c) /a≦1.4, the battery is charged with a large current that clearly generates gas. In addition, the internal pressure of the storage battery does not become too high, causing the battery case to swell, and the valve opening pressure is too low to release a large amount of gas, reducing the electrolyte and reducing the capacity. In addition, it was found that stable operation was possible.
[0023]
【The invention's effect】
Depending on the shape and mounting conditions of the valve, when charged with a large current that generates gas depending on the valve shape and mounting conditions, the battery case swells and discharges a large amount of gas, leading to a depletion of the electrolyte. According to the present invention, the distance between the upper surface of the top surface of the cap-type valve mounted on the storage battery and the lower surface of the top lid of the battery case may be a (mm). When the thickness of the top surface of the valve is b (mm) and the length of the skirt portion of the valve is c (mm),
By maintaining the relationship of 1 <(b + c) /a≦1.4, the control valve opens at a pressure within an appropriate range, and a controllable valve-type lead storage battery with stable performance is obtained. The effect is extremely large.
[Brief description of the drawings]
FIG. 1 is a sectional view of an essential part showing a state in which a bowl type (cap type) valve is mounted on a valve seat.
FIG. 2 is a diagram showing a relationship between (b + c) / a and a valve opening pressure (b and c are fixed).
FIG. 3 is a diagram showing a relationship between (b + c) / a and a valve opening pressure (a and c are fixed).
FIG. 4 is a diagram showing the relationship between (b + c) / a and the valve opening pressure (a and b are fixed).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cap-type valve main body 2 Valve skirt part 3 Top surface of valve 4 Valve seat 5 Top lid
