Battery Housing Decoupling for Impact-Resistant Power Tools

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Solution Overview

Problem

Hand-held power tools, such as angle grinders, are prone to damage from impact stress, which can deform the motor mounting unit and impair the efficiency of the electric motor due to lack of concentricity in the rotor, and using multiple battery packs requires a large installation space and unwieldy design.

Innovation Solution

The power tool features a housing decoupled from the motor support unit, allowing the housing to absorb inertial forces from impacts and a motor support unit design with symmetrical battery pack mounts for compactness and optimized weight distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the housing is directly attached to the motor support unit, then the structure is simpler and more rigid, but impact forces are directly transmitted to the motor support unit causing damage

Engineering Contradiction:
Improveimpact resistanceVSAvoidstructural complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The housing is divided into two separate parts: the main housing and the receiving housing. These segments are connected through a damping element rather than being rigidly attached, allowing impact forces to be absorbed without directly transmitting to the motor support unit. This segmentation resolves the contradiction by creating a structured yet flexible connection that protects against impact while maintaining structural integrity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

A damping element is introduced as an intermediary component between the housing and the motor support unit. This mediator absorbs and dissipates impact forces, preventing direct force transmission that would otherwise damage the motor support unit. The damping element serves as a buffer that reconciles the need for structural rigidity with impact protection.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Use of energy by moving object

If multiple battery packs are mounted in the receiving housing, then the energy capacity increases, but the installation space requirement and device unwieldiness increase

Engineering Contradiction:
Improveenergy capacityVSAvoidinstallation space
Core Design Contradiction:
Use of energy by moving objectVSVolume of moving object

Solution Approach 1:

The receiving housing containing multiple battery packs is nested within or integrated with the main housing structure. This nesting arrangement allows multiple battery packs to be accommodated in a compact configuration, increasing energy capacity without proportionally increasing the overall device volume. The nested structure optimizes space utilization while maintaining accessibility.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The receiving housing is designed to utilize three-dimensional space efficiently, arranging battery packs in multiple dimensions rather than a simple linear configuration. This dimensional optimization allows multiple battery packs to be mounted within a compact footprint, increasing energy capacity without making the device unwieldy or excessively large.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If the motor support unit is made rigid for precise tool guidance, then the guidance precision improves, but the unit becomes vulnerable to impact damage

Engineering Contradiction:
Improvetool guidance precisionVSAvoidimpact vulnerability
Core Design Contradiction:
Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The motor support unit is extracted from the direct impact path by decoupling it from the housing through the damping element. This extraction allows the motor support unit to maintain its rigid structure for precise tool guidance while removing it from the harmful impact force transmission path. The damping element isolates the rigid motor support unit from impact forces.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The damping element serves as a protective intermediary between the rigid motor support unit and the external impact forces. This mediator allows the motor support unit to remain rigid for precision guidance while the damping element absorbs and dissipates impact forces before they can reach the motor support unit, resolving the vulnerability to impact damage.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 enhances resistance to impact loads by reducing direct force transmission to the motor support unit, preventing damage and ensuring a compact, user-friendly design with improved handling and weight distribution.

Implementation Method 1

The deformation, preferably elastic deformation, of the housing absorbs the inertial forces of the receiving housing and the at least one battery pack before the receiving housing can contact the motor support unit due to the housing deformation.

Methodology Applied
Scientific EffectDeformation: Deformation

Implementation Method 2

The deformation, preferably elastic deformation, of the housing absorbs the inertial forces

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 3

the receiving housing and the motor support unit are designed and arranged relative to each other in such a way that the receiving housing is movable relative to the motor support unit in order to reduce, and in particular avoid, a direct transmission of inertial forces emanating from the receiving housing to the motor support unit in the event of an impact load on the working device

Methodology Applied
Scientific EffectInertial forces: Inertia

Data Source

PatentEP4640350A1Working machine
Publication Date: 2025.10.29 ANDREAS STIHL AG & CO KG
  • EP4640350A1 patent drawingFigure 1~2
  • EP4640350A1 patent drawingFigure 3~4
  • EP4640350A1 patent drawingFigure 5~6

AI summary

The invention relates to a work device comprising a housing (2), a motor support unit (10) formed separately from the housing (2), wherein the housing (2) is fixed to the motor support unit (10), wherein a drive motor (3) is designed as an electric motor for driving a tool (5) and is attached to the motor support unit (10), a receiving housing (20) formed separately from the motor support unit (10) for receiving at least one battery pack (7) for supplying the drive motor (3) with electrical energy, wherein the receiving housing (20) is fixed to the housing (2), and wherein the receiving housing (20) and the motor support unit (10) are designed and arranged relative to each other such that the receiving housing (20) is movable relative to the motor support unit (10) in order to reduce, and in particular to avoid, a direct transmission of inertial forces emanating from the receiving housing (20) to the motor support unit (10) in the event of an impact load on the work device (1).