Lead-Acid Battery Terminal Bushing Surface Roughness
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Solution Overview
Problem
Lead-acid batteries face issues with electrolyte solution exuding through minute air gaps between the bushing and the cover, leading to contamination and miniaturization challenges in narrow spaces.
Innovation Solution
A lead-acid battery terminal member with a cylindrical bushing featuring annular projecting portions and a lower surface roughness on the outer periphery compared to the terminal portion, which narrows the gap and enhances water repellency, preventing electrolyte solution exudation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the bushing length is shortened to increase the rate that constitutional members occupy in the lead-acid battery, then the miniaturization of the battery is improved, but the creeping distance of the air gap between the bushing and cover becomes shorter causing electrolyte solution to exude
Solution Approach 1:
The invention applies different surface roughness characteristics to different portions of the bushing. Specifically, the outer peripheral surface of the bushing has a roughness Rz of 0.4μm or less (smoother), while the terminal portion has a roughness Rz of 0.8μm or more (rougher). This local differentiation creates a water repellent effect at the terminal portion that prevents electrolyte solution from spreading, while the smoother bushing surface maintains proper contact with the cover to prevent exudation even with shorter bushing length.
Solution Approach 2:
The invention changes the surface roughness parameter of the bushing to resolve the contradiction. By controlling the roughness Rz of the outer peripheral surface to be 0.4μm or less and the terminal portion to be 0.8μm or more, the invention creates optimal conditions for both preventing electrolyte solution exudation through the air gap and preventing spreading at the terminal portion, thereby maintaining reliability while allowing for miniaturization.
2Adaptability or versatility
If the bushing length is shortened to enhance performance in narrow spaces, then the adaptability to narrow spaces is improved, but the creeping distance becomes shorter causing electrolyte solution to climb up and exude
Solution Approach 1:
The invention applies different surface roughness characteristics to different portions of the bushing. Specifically, the outer peripheral surface of the bushing has a roughness Rz of 0.4μm or less (smoother), while the terminal portion has a roughness Rz of 0.8μm or more (rougher). This local differentiation creates a water repellent effect at the terminal portion that prevents electrolyte solution from spreading, while the smoother bushing surface maintains proper contact with the cover to prevent exudation even with shorter bushing length.
Solution Approach 2:
The invention changes the surface roughness parameter of the bushing to resolve the contradiction. By controlling the roughness Rz of the outer peripheral surface to be 0.4μm or less and the terminal portion to be 0.8μm or more, the invention creates optimal conditions for both preventing electrolyte solution exudation through the air gap and preventing spreading at the terminal portion, thereby maintaining reliability while allowing for miniaturization.
3Reliability
If the surface roughness of the terminal portion is made lower to suppress electrolyte solution exudation, then the electrolyte solution containment is improved, but the water repellency at the terminal portion is reduced
Solution Approach 1:
The invention applies different surface roughness characteristics to different portions of the bushing. Specifically, the outer peripheral surface of the bushing has a roughness Rz of 0.4μm or less (smoother), while the terminal portion has a roughness Rz of 0.8μm or more (rougher). This local differentiation creates a water repellent effect at the terminal portion that prevents electrolyte solution from spreading, while the smoother bushing surface maintains proper contact with the cover to prevent exudation even with shorter bushing length.
Solution Approach 2:
The invention changes the surface roughness parameter of the bushing to resolve the contradiction. By controlling the roughness Rz of the outer peripheral surface to be 0.4μm or less and the terminal portion to be 0.8μm or more, the invention creates optimal conditions for both preventing electrolyte solution exudation through the air gap and preventing spreading at the terminal portion, thereby maintaining reliability while allowing for miniaturization.
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
Effectively suppresses electrolyte solution exudation and prevents it from spreading and wetting the terminal portion, maintaining the battery's performance and miniaturization goals.
Implementation Method 1
the shorter the length of the bushing, the shorter a creeping distance of a portion where an outer peripheral surface of the bushing and the cover face each other in an opposed manner becomes so that an electrolyte solution in the container tends to climb up through a minute air gap between the outer peripheral surface of the bushing and the cover
Implementation Method 2
surface roughness of at least a portion of the outer periphery of the bushing which faces a resin which forms the cover is lower than surface roughness of the terminal portion
Data Source
AI summary
A lead-acid battery terminal member includes: a terminal portion which is arranged in a resin-made cover for closing a container; and a cylindrical bushing which is connected to the terminal portion through a conducting portion. The bushing is embedded in the cover, and has a plurality of annular projecting portions formed on an outer periphery thereof. Poles extending from an electrode group arranged in the container are inserted into and are welded to the bushing. Surface roughness of a surface of the annular projecting portion which faces a resin forming the cover in an opposed manner is lower than surface roughness of a surface of a portion other than the annular projecting portion.