Deployable Lifting Step Assembly for Safer Cabin Access

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Solution Overview

Problem

Existing lifting step assemblies for industrial vehicles are impractical and hazardous due to inadequate spacing between steps, particularly for shorter users, and often position the mobile step too far forward from the seat, making ingress and egress uncomfortable and unsafe.

Innovation Solution

A lifting step assembly with a second step member that deploys laterally when the first step member reaches its upper position, allowing users to face the cabin door directly, and a deployment mechanism using an electric motor with a clutch mechanism that automatically switches positions based on distance thresholds, ensuring safe and easy access without additional sensors or actuators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single mobile step is used for cabin access, then the structure is simple, but the spacing between steps is too large making it unsafe and uncomfortable for users

Engineering Contradiction:
Improvestructure simplicityVSAvoidsafety of access
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The single mobile step is divided into two step members (first step member and second step member) that can deploy sequentially. The first step member provides initial support, while the second step member deploys when the first approaches its upper position, creating intermediate spacing that reduces the risk of falling and improves user comfort during cabin access.

Inventive Principle:
Principle #1Segmentation

2Device complexity

If the mobile step is positioned far forward from the seat, then the lifting mechanism is simpler, but ingress and egress become impractical and hazardous

Engineering Contradiction:
Improvemechanism simplicityVSAvoidpracticality of access
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The second step member is configured to move laterally away from the hinge axis of the cabin door in addition to the vertical movement. This lateral displacement in a second dimension allows the step to position itself optimally relative to the cabin door opening, enabling users to face the door sill directly and improving practicality of access without complicating the fundamental lifting mechanism.

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

3Reliability

If a second step member is added to improve safety, then the spacing between steps is reduced, but the device complexity increases

Engineering Contradiction:
Improvesafety of accessVSAvoidnumber of step members
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The deployment mechanism for the second step member is integrated with the existing lifting mechanism. The same electric motor that drives the first step member's vertical movement also controls the deployment of the second step member through a clutch mechanism. This merging of functions adds the safety benefit of reduced step spacing while minimizing the increase in device complexity through shared components.

Inventive Principle:
Principle #5Merging (Combining)

4Reliability

If the second step member is always deployed, then access is always safe, but the device size and space requirements increase

Engineering Contradiction:
Improveconsistent safetyVSAvoidspace occupation
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The second step member is designed to deploy dynamically only when needed - specifically when the first step member comes close to its upper position during the lifting operation. When not in use, the second step member can be retracted or positioned to minimize space occupation. This dynamic deployment approach maintains consistent safety during operation while reducing space requirements when the system is idle.

Inventive Principle:
Principle #15Dynamics

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 the practicality and safety of accessing the cabin by reducing the risk of falling and improving ease of use through precise positioning of the second step member, utilizing a compact and robust design that integrates the deployment mechanism with the lifting operation.

Implementation Method 1

an electric motor rigidly linked to the first step member, the electric motor comprising a first driving pinion

Methodology Applied
Scientific EffectElectric motor:

Implementation Method 2

a rack configured for being fixed to a structural element of the industrial vehicle, the first driving pinion being engaged with the rack so that the first step member moves from the first position to the second position

Methodology Applied
Scientific EffectRack and pinion: Rack and Pinion

Data Source

PatentEP4257429B1Lifting step assembly for an industrial vehicle
Publication Date: 2024.06.12 VOLVO TRUCK CORP
  • EP4257429B1 patent drawingFigure 1
  • EP4257429B1 patent drawingFigure 2
  • EP4257429B1 patent drawingFigure 3

AI summary

The invention relates to a lifting step assembly (50) for helping a user entering a cabin (60) of an industrial vehicle (100), the lifting step assembly (50) comprising : - a first step member (1) configured for selectively moving along a first translation direction (T1) between a first position (L) said lower position and a second position (U) said upper position, so that the user can be lifted from the first position (L) to the second position (U), - a second step member (2) configured for being moved between a retracted position (R) and a deployed position (D) in which the second step member (2) projects out of the first step member (1), - a deployment mechanism (3) configured for moving the second step member (2) from the retracted position (R) to the deployed position (D) when the distance between the first step member (1) and the second position (U) becomes lower than a predetermined threshold (Th).