Articulated Step System Using Tension Struts and Standoff Brackets
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Solution Overview
Problem
Existing deployable steps for vehicles, such as pickup trucks, face limitations in load carrying capability and robustness due to inadequate mounting systems that fail to handle the moment created by a person's weight, particularly when using single bracket mounting or compression-based systems.
Innovation Solution
An articulated step system that utilizes standoff brackets and tension struts to support the step in shear, combined with a four-bar linkage or pivot joint mechanism, allowing the step to extend outwardly from the vehicle body while accommodating the moment caused by a person's weight, and can be easily integrated during vehicle assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bracket mounting system is used to support the step, then the device complexity is reduced, but the load carrying capability and robustness deteriorate due to inability to handle the moment created by user weight
Solution Approach 1:
The mounting system is segmented into multiple components: standoff brackets mounted to the frame and tension struts extending to the body. This segmentation allows each component to handle specific forces, with the tension struts absorbing the moment loads that a single bracket cannot handle, thereby resolving the contradiction between simplicity and strength.
Solution Approach 2:
The mounting system transitions from a single-point attachment to a distributed attachment system involving both frame-mounted brackets and body-mounted tension struts. This dimensional expansion creates a triangular support structure that handles both vertical loads and moment forces, resolving the strength limitation while maintaining reasonable complexity.
2Ease of manufacture
If a compression-based mounting system is used, then the ease of manufacture is improved, but the load carrying capability deteriorates due to limited robustness
Solution Approach 1:
Instead of using compression-based mounting, the system inverts the approach by using tension-based mounting through the tension struts. The struts are pre-tensioned to create a rigid triangular structure that handles loads more effectively, improving robustness while remaining manufacturable through standard fastening procedures.
3Ease of operation
If the step is made longer to provide better access, then the ease of operation is improved, but the stability deteriorates due to increased moment arm and higher moment loads
Solution Approach 1:
The step is supported in a third dimension by the tension struts extending from the body to the step housing, creating a triangular support structure. This dimensional support counteracts the increased moment arm effect of a longer step, maintaining stability while allowing the step to extend further for improved access.
Solution Approach 2:
The tension struts act as counterbalancing elements that offset the moment arm effect of the extended step. By positioning the struts to create opposing moment forces, the system counterweights the destabilizing effect of the longer step, enabling both extended reach and stability.
Data Source
AI summary
An articulated step system for an automotive vehicle includes a step housing attached to the vehicle frame by means of at least one standoff bracket and a tension strut extending generally downwardly from a first end attached to a vehicle body to a second end attached to the step housing. The articulated step has a stowed position generally underlying the body, and a deployed position extending generally outwardly from the body. Movement of the step may be either translational or rotational with respect to the step housing. In one embodiment, the step extends for the full length of the cab of the vehicle, and partially under a load carrying body at the rear of the vehicle.