Valve Element Design for Alkaline Battery Pressure Control
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Solution Overview
Problem
The working pressure of the valve element in existing alkaline secondary batteries is limited, making it difficult to extend battery life without risking explosion, as the valve element opens prematurely due to low pressure thresholds, leading to the discharge of alkaline electrolyte.
Innovation Solution
The design includes a valve element with a cylindrical main body and an extended diameter part, where the ratio of the thickness of the extended diameter part to the total height of the valve element is adjusted to increase the working pressure, using ethylene propylene diene rubber, to prevent premature opening and electrolyte discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the working pressure of the valve element is increased to extend battery life, then the frequency of air vent opening is reduced and battery life is extended, but the risk of battery explosion increases if the pressure approaches the deformation pressure of the outer package can
Solution Approach 1:
The invention changes the geometric parameters of the valve element, specifically the ratio of the thickness of the extended diameter part to the total height (27-47%), to optimize the working pressure. This parameter optimization allows the valve to maintain high working pressure (extending battery life) while ensuring the pressure remains below the outer package can's deformation pressure (preventing explosion).
Solution Approach 2:
The valve element includes an extended diameter part that protrudes into the cap member, creating a partial structural extension. This extended diameter part (with thickness ratio 27-47%) provides additional compression resistance and structural support, allowing the valve to withstand higher pressures without full opening, thus extending battery life while maintaining safety margins.
2Ease of operation
If the working pressure of the valve element is low, then the valve element opens easily to discharge gas, but the air vent opens prematurely with small pressure increases, causing frequent alkaline electrolyte discharge and shortening battery life
Solution Approach 1:
The invention optimizes the geometric parameters of the valve element, specifically setting the ratio of the thickness of the extended diameter part to the total height between 27-47%. This parameter change increases the working pressure requirement for opening, preventing premature opening while maintaining controlled opening capability when truly needed.
Solution Approach 2:
The extended diameter part of the valve element creates a partial structural reinforcement that increases the force required to open the valve. This partial extension (protruding into the cap member) provides additional mechanical resistance, preventing the valve from opening with small pressure increases while still allowing it to open when necessary pressure is reached.
3Stress or pressure
If the hardness of rubber or compression ratio of the valve element is increased to raise working pressure, then the working pressure increases, but it is difficult to further increase the pressure close to the explosion pressure without compromising other performance
Solution Approach 1:
Instead of simply increasing rubber hardness or compression ratio, the invention changes the geometric parameters of the valve element structure, specifically the ratio of the thickness of the extended diameter part to the total height (27-47%). This geometric parameter change achieves higher working pressure while maintaining rubber elasticity and overall battery reliability.
Solution Approach 2:
The invention adds a dimensional feature to the valve element by creating an extended diameter part that protrudes into the cap member. This dimensional change (from a simple cylindrical shape to a stepped cylindrical shape with extended diameter) provides additional structural support and compression resistance, achieving higher working pressure without compromising reliability through material hardening or excessive compression.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design significantly increases the working pressure of the valve element, reducing unnecessary openings and extending battery life by maintaining sealability and preventing electrolyte discharge, while ensuring safety by operating before the battery reaches deformation pressure.
Implementation Method 1
The valve element is made of an elastic material, such as a rubber-based material, and has a cylindrical shape. The valve element is in the state of being compressed between the top wall of the cap member and the cover plate and closes the opening edge of the air vent
Implementation Method 2
When gas is abnormally generated in the battery and the pressure of the gas in the battery increases and exceeds the predetermined pressure, the valve element is elastically deformed by the pressure of the gas to open the air vent of the cover plate
Data Source
Figure 1
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AI summary
A nickel-metal hydride secondary battery 2 is provided with: an outer package can 10 having an opening at an upper end; an electrode group 22 accommodated in the outer package can 10 together with an alkaline electrolyte; and a sealing body 11 that seals the opening of the outer package can 10. The sealing body 11 includes a cover plate 14 having a central through hole 16, and a valve element 18 made of an elastic material to close the central through hole 16. The valve element 18 includes a cylindrical main body part 54 having a base end surface 58 that covers the central through hole 16, and an extended diameter part 56 positioned on an opposite side of the main body part 54 from the base end surface 58 and having a diameter made larger than a diameter of the main body part 54. A ratio R of a thickness T of the extended diameter part 56 to a total height H of the valve element 18 is equal to or higher than 27%.