Cabin Load Path Structure Around Rear Window Lower Corner

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Solution Overview

Problem

Existing working machines, such as hydraulic excavators, are prone to crack formation around the lower corner of the window edge due to applied loads, which compromises the cabin's stiffness and visibility.

Innovation Solution

A load transmitting member comprising a single, continuous structure with an upper pillar part, intermediate part, and beam part is integrated into the cabin's framework, transmitting lateral loads efficiently while avoiding welded joints at the corner, thus preventing crack formation and maintaining cabin stiffness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a conventional cabin structure with window edges is used, then visibility through the window is ensured, but cracks are likely to occur in the corner adjacent portion around the lower corner of the window edge when large loads are applied

Engineering Contradiction:
Improvevisibility through windowVSAvoidcrack resistance in corner adjacent portion
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent extracts the problematic corner adjacent portion from the load transmission path by introducing a cutout section in the rear wall. This removes the vulnerable area where cracks occur, allowing the load transmitting member to bypass this weak point while maintaining window functionality in the remaining area.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The load transmitting member acts as an intermediary element that transfers lateral loads from the upper portion of the cabin to the lower portion, bypassing the corner adjacent portion. This mediator prevents direct loading of the vulnerable corner area while maintaining structural integrity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the cabin structure is reinforced to prevent crack occurrence, then reliability is improved, but the complexity of the structure increases

Engineering Contradiction:
Improvecrack suppression in corner adjacent portionVSAvoidcabin structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The load transmitting member is merged with the rear wall structure, forming an integrated assembly. This combining of functions (load transmission and structural support) into a single element reduces overall structural complexity while maintaining crack suppression capabilities.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The load transmitting member serves multiple functions: it transmits lateral loads, provides structural support to the rear wall, and acts as a reinforcement element to prevent cracks. This multi-functionality reduces the need for separate reinforcement components, simplifying the overall structure.

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

3Stability of the object's composition

If a load transmitting member is added to transmit lateral loads, then cabin stiffness is improved, but the device complexity increases

Engineering Contradiction:
Improvecabin stiffnessVSAvoidcabin framework complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The load transmitting member is integrated with the rear wall and window edge structure, forming a unified assembly. This merging eliminates the need for separate attachment components and simplifies the overall cabin framework while maintaining enhanced stiffness.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The load transmitting member extends in multiple dimensions (vertically along the rear wall and horizontally across the window edge), creating a three-dimensional reinforcement structure. This dimensional approach provides comprehensive stiffness enhancement without requiring additional separate components.

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

Data Source

PatentEP3978690B1Working machine
Publication Date: 2025.11.26 KOBELCO CONSTR MASCH CO LTD
  • EP3978690B1 patent drawingFigure 1
  • EP3978690B1 patent drawingFigure 2
  • EP3978690B1 patent drawingFigure 3

AI summary

A working machine (10) includes a load transmitting member (60) including: an upper pillar part (64); an intermediate part (62) extending to circumvent a window (53) from a position above a lower corner (C1) of a window edge of the window (53) and outer than the lower corner (C1) in a wall width direction (W1) to a position below the lower corner (C1) and inner than the lower corner (C1) in the wall width direction (W1); and a beam part (65) extending so as to be farther away from a wall side edge (E1) under the window (53). The upper pillar part (64), the intermediate part (62), and the beam part (65) are continuous in this order so that a load (F) applied to an upper portion of a cabin (30) is transmitted to an upper frame. At least the intermediate part (62) of the load transmitting member (60) is made of a single member.