Resettable Pneumatic Battery Safety Switch

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Solution Overview

Problem

Existing lithium-ion batteries face safety risks due to potential fire and explosive combustion from mechanical damage or overcharging, with existing safety devices often resulting in an irreversible and critical state that cannot be actively changed after triggering.

Innovation Solution

A battery design featuring a pneumatically actuable electrical switch that interrupts electrical connections between pole bolts and electrodes when internal pressure rises above a threshold, with a bistable membrane and resetting device allowing for controlled restoration of electrical connections without opening the housing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing safety devices (fuses, circuit breakers) are used to prevent fire and explosive combustion, then safety reliability is improved, but the battery enters an irreversible critical state that cannot be actively changed

Engineering Contradiction:
ImprovesafetyVSAvoidability to change state
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies the dynamics principle by designing a safety device with a movable piston that can transition between different states. The piston is initially in a first position allowing electrical connection, and upon pressure increase, it moves to a second position to interrupt the connection. The key innovation is that the piston can be actively reset from the second position back to the first position, making the safety device dynamic and reversible rather than static and irreversible.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The safety device incorporates a reset mechanism that enables the piston to return to its initial position automatically or through external actuation. This self-service feature allows the battery system to restore functionality after a safety trigger event without requiring complete replacement of components, thereby maintaining adaptability while preserving safety functionality.

Inventive Principle:
Principle #25Self-service

2Object-affected harmful factors

If irreversible safety devices are triggered to eliminate immediate hazards, then harmful factors are reduced, but the battery remains in a critical state requiring replacement or opening of housing

Engineering Contradiction:
Improvefire and explosive combustion riskVSAvoidability to restore functionality
Core Design Contradiction:
Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent introduces a reset mechanism as an intermediary component that mediates between the triggered safety state and the functional operational state. This intermediary allows controlled restoration of the electrical connection by actively moving the piston back to its initial position, enabling the battery to transition from a critical state back to normal operation without requiring housing opening or component replacement.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If a piston mechanism is used to interrupt electrical connection upon pressure increase, then safety switching is achieved, but sealing the piston against the cylindrical receptacle is difficult and air/moisture ingress must be prevented

Engineering Contradiction:
Improvesafety switchingVSAvoidsealing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a membrane as a flexible sealing element between the piston and the cylindrical receptacle. This membrane provides an effective seal that prevents air and moisture ingress while accommodating the piston's movement between positions. The flexible nature of the membrane allows it to maintain sealing effectiveness throughout the piston's travel range without requiring complex sealing mechanisms.

Inventive Principle:
Principle #30Flexible shells and thin films

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

The solution provides a reliable and simple safety mechanism that prevents further risk after triggering, allowing for controlled discharge of a critical battery state and maintaining safety without irreversible deactivation.

Implementation Method 1

upon a pressure increase within the housing from an initial value above a threshold value, changes its switching state

Methodology Applied
Scientific EffectPressure increase: Pressure Increase

Implementation Method 2

upon a pressure decrease within the housing below a threshold value, restores the electrical connection

Methodology Applied
Scientific EffectPressure decrease: Pressure Drop

Data Source

PatentEP2994949B1Battery with a safety device which can be reset, and also suitable pole stud for said battery
Publication Date: 2020.10.14 VARTA MICROBATTERY GMBH
  • EP2994949B1 patent drawingFigure 1a~1c
  • EP2994949B1 patent drawingFigure 2A~2B

AI summary

The invention describes a battery having a housing, at least one individual cell which is arranged in said housing and has at least one positive and at least one negative electrode and also at least one positive and/or negative pole stud which is routed through the housing. The battery comprises at least one electrical switch which can be pneumatically operated, changes its switching state in the event of a pressure increase within the housing above a threshold value and, in the process, interrupts an existing electrical connection between at least one of the pole studs and the at least one electrode which is connected to said pole stud. The battery is distinguished in that it comprises a resetting device with which an electrical connection which is interrupted as a result of a change in the switching state can be re-established without it being necessary to open the housing for this purpose. The invention also describes a pole stud which is suitable for the described battery. Said pole stud comprises a head with two opposite flat faces, and comprises a shaft which extends out of one of the flat faces and has a free shaft end, and is characterized by a hollow space within the head, a gas-impermeable diaphragm which bounds the hollow space, and also a passage hole through the shaft, which passage hole issues into the hollow space.