Battery Pack Safety Fuse With Thermal Assist Triggering

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Solution Overview

Problem

Existing safety devices for battery cells face issues such as unprotected areas due to varying triggering characteristics of safety elements, inefficiencies, and the use of expensive non-standard components, which can lead to safety hazards and increased costs.

Innovation Solution

A safety device comprising a carrier element, heating unit, and control unit that assists in triggering a safety element by applying thermal and electrical stress, using a fuse element designed as a copper track or metal strip fuse, with a heating element coupled to the fuse to interrupt current flow in critical states, and a control unit to activate the heating unit based on detected parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional safety elements (fuse, CID) are used with different triggering characteristics, then current interruption can be achieved, but unprotected areas arise at certain charge levels combined with certain short-circuit resistances

Engineering Contradiction:
Improvesafety coverageVSAvoidtriggering characteristic variability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The heating unit changes the thermal parameter of the safety element by applying controlled heating, enabling the safety element to trigger at lower temperature differences. This allows the safety device to protect against a broader range of short-circuit resistances and charge levels, eliminating unprotected areas while maintaining reliable triggering across different operating conditions.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The heating unit is activated in advance to pre-heat the safety element before the actual triggering event. This preliminary thermal action reduces the temperature difference required for triggering, ensuring that the safety element responds reliably across all charge levels and short-circuit resistance values, thereby eliminating unprotected operating areas.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If expensive non-standard components are used in safety devices, then safety functionality can be achieved, but cost efficiency deteriorates

Engineering Contradiction:
Improvesafety functionalityVSAvoidcost efficiency
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The heating unit employs a simple resistive heating element made from standard copper traces or wire, replacing expensive non-standard heating components. This inexpensive heating mechanism achieves the required safety functionality by providing controlled thermal assistance to the safety element, significantly reducing component costs while maintaining reliable operation.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The heating unit can be implemented using standard PCB copper traces that serve dual purposes: as part of the circuit board structure and as the heating element. This universal approach eliminates the need for specialized heating components, reducing manufacturing complexity and cost while maintaining effective safety functionality across different battery pack designs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If complex safety device designs are used, then comprehensive protection can be achieved, but manufacturing complexity and efficiency deteriorate

Engineering Contradiction:
Improveprotection comprehensivenessVSAvoiddesign complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The heating unit is integrated directly into the existing safety element structure, combining the heating function with the safety element itself. This merged design eliminates separate heating components and complex assembly procedures, reducing manufacturing complexity while maintaining comprehensive protection through the combined thermal-assist and current-interruption functions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The heating element is constructed from the same material (copper) and manufacturing process (PCB tracing) as the existing circuit board infrastructure. This homogeneous approach allows the heating unit to be manufactured using standard PCB fabrication processes without requiring additional manufacturing steps or specialized components, thereby simplifying production while achieving comprehensive safety protection.

Inventive Principle:
Principle #33Homogeneity

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

Enhances safety by promoting precise triggering of the safety element, reduces costs through standard components, and simplifies design and manufacturing, while ensuring reliable protection against short circuits and overheating.

Implementation Method 1

a heating unit coupled to the safety element, in particular electrically and/or thermally and/or mechanically, and provided to assist in triggering the safety element

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The fuse element can, without being limited thereto, be designed, for example, as a fuse and/or as a sheet metal strip fuse

Methodology Applied
Scientific EffectMelting: Melting

Data Source

PatentEP4386805B1Safety device, battery pack having a safety device, and method for producing a safety device
Publication Date: 2025.10.15 ROBERT BOSCH GMBH
  • EP4386805B1 patent drawingFigure 1
  • EP4386805B1 patent drawingFigure 2
  • EP4386805B1 patent drawingFigure 3

AI summary

The invention relates to a safety device (10a-f) for at least one battery cell (12a), comprising a safety element (14a-f) for interrupting current flow from the battery cell (12a) in a critical state of the battery cell (12a), a heating unit (16a-f) which is coupled to the safety element (14a-f), in particular electrically and/or thermally and/or mechanically, and is provided to assist in triggering the safety element (14a-f), and a control unit (18a) for activating the heating unit (16a-f) in the critical state. It is proposed that the safety device (10a-f) comprises at least one support element (20a-f) for receiving the safety element (14a-f) and at least one heating element (22a-f) of the heating unit (16a-f).