Collapsible Cabin Step Assembly for Low-Drag Truck Access

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Solution Overview

Problem

Existing boarding step assemblies for industrial vehicles require a recessed area on the side of the truck, which increases aerodynamic losses, alters the vehicle's sleek shape, and occupies valuable space.

Innovation Solution

A collapsible step assembly that deploys from a stowed position flush with the truck's surface when the entry door is opened, eliminating the need for a recessed area and allowing the space to be used for other components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a recessed area is formed on the side of the truck to accommodate fixed steps, then the steps can be installed, but the sleek shape of the side of the cabin is altered and aerodynamic losses increase

Engineering Contradiction:
Improvestep installationVSAvoidaerodynamic losses
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The step assembly is designed to be movable between a retracted position (flush with the vehicle body) and a deployed position (protruding outward). This dynamic configuration allows the step to provide functionality only when needed, while maintaining an aerodynamic profile during vehicle operation, thus resolving the contradiction between step installation and aerodynamic performance

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The step assembly is divided into separate components including a fixed support structure and a movable step member that can be deployed independently. This segmentation allows the step to be installed without creating a permanent recess, as the movable portion can be stored within or alongside the fixed structure, eliminating the need for aerodynamic-compromising recesses

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If a recessed area is formed on the side of the truck to accommodate fixed steps, then the steps can be installed, but the drag coefficient increases

Engineering Contradiction:
Improvestep installationVSAvoiddrag coefficient
Core Design Contradiction:
Ease of manufactureVSLoss of energy

Solution Approach 1:

The step assembly transitions from a static recessed configuration to a dynamic deployable system. During vehicle operation, the step remains retracted or flush with the body surface, maintaining streamlined airflow and reducing drag coefficient. When needed, the step deploys to provide boarding assistance, thus eliminating the permanent energy loss associated with fixed recessed steps

Inventive Principle:
Principle #15Dynamics

3Ease of manufacture

If the step is installed in the same vertical plane as the entry door frame, then installation is simplified, but access becomes impractical as users feel too close from the door

Engineering Contradiction:
Improvestep installationVSAvoidaccess
Core Design Contradiction:
Ease of manufactureVSEase of operation

Solution Approach 1:

The step assembly is designed to project outward from the vehicle body in a direction perpendicular to the door plane, creating additional spatial dimension for access. This allows the step to be positioned optimally for user approach while the door remains in its original plane, resolving the contradiction between simplified installation and practical access by utilizing three-dimensional space rather than being constrained to a single vertical plane

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

4Object-affected harmful factors

If a collapsible step assembly is deployed to eliminate recessed area, then aerodynamic losses are reduced, but the device complexity increases

Engineering Contradiction:
Improveaerodynamic lossesVSAvoidstep assembly structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The step assembly incorporates automatic deployment and retraction mechanisms that activate based on door position sensors or manual triggers. The system self-manages its configuration without requiring complex control systems or multiple actuators, as the deployment is directly coupled with door operation, thus reducing aerodynamic losses while minimizing the increase in device complexity through self-regulating design

Inventive Principle:
Principle #25Self-service

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 collapsible step assembly improves access to the vehicle by providing a stable step without protruding from the truck's surface, reduces drag coefficient, and allows for the integration of additional components in the previously recessed area.

Implementation Method 1

an elastic member configured for moving the collapsible step member from the deployed position to the stowed position in response to a closing of the entry door

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

the actuation cable is configured to link the collapsible step member and the check link

Methodology Applied
Scientific EffectTension: Tension

Data Source

PatentEP4212391B1Collapsible step assembly for an industrial vehicle
Publication Date: 2025.06.04 VOLVO TRUCK CORP
  • EP4212391B1 patent drawingFigure 1
  • EP4212391B1 patent drawingFigure 2
  • EP4212391B1 patent drawingFigure 3(A)~3(B)

AI summary

The invention relates to a collapsible step assembly (1) for helping a user entering a cabin (50) of an industrial vehicle (100), the collapsible step assembly (1) comprising: - a collapsible step member (4) configured to be movable between : -- a stowed position (S) in which the collapsible step member (4) is set-back from or flush with an external surface of the industrial vehicle (100), and -- a deployed position (E) in which the collapsible step member (4) projects out of the external surface of the industrial vehicle (100), - an actuation member (3) configured to link the collapsible step member (4) and an entry door of the cabin (40), in which the collapsible step member (4) is configured to be moved from the stowed position (S) to the deployed position (E) by the actuation member (3) in response to an opening of the entry door (40).