Virtual-Pivot Armrest Mechanism for Neutral Wrist Position

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Solution Overview

Problem

Existing materials handling vehicles often have armrests that are either fixed, making them uncomfortable for operators of varying heights, or adjustable but costly to manufacture, and fail to maintain an ergonomically neutral wrist position for operators.

Innovation Solution

An adjustable armrest mechanism that pivots about a virtual pivot point and features a contoured pad sloping downward towards the control handle, allowing operators to rest their elbow and forearm comfortably without excessive wrist flexion, with a locking device to secure the armrest in multiple positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a fixed armrest is provided, then the structure is simple and manufacturing cost is low, but operators of varying heights cannot use it comfortably

Engineering Contradiction:

Improvemanufacturing costVSAvoidadaptability to different operator heights

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The armrest is designed to be adjustable rather than fixed, allowing it to move between multiple positions. The armrest apparatus can be repositioned along an arc-shaped path to accommodate operators of different heights, transforming a static structure into a dynamic one that adapts to user needs.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The armrest position is changed by adjusting its location along the arc-shaped path. By varying the position parameter of the armrest, the system accommodates different operator heights while maintaining ergonomic alignment with the control handle.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If an adjustable armrest is provided to accommodate different operator heights, then adaptability improves, but manufacturing cost increases

Engineering Contradiction:

Improveadaptability to different operator heightsVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The armrest uses a simple mechanical linkage system with a pivot point and arc-shaped slot to enable adjustment. This dynamic mechanism allows multi-position adjustment without requiring complex motors or electronic controls, keeping manufacturing costs reasonable.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The adjustment mechanism is divided into separate components: a base with guide members, an armrest apparatus with arc-shaped slots, and a locking device. This segmentation allows for easier manufacturing and assembly while achieving the desired adjustability.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If the armrest is adjustable up and down along a linear path, then adaptability improves, but the control handle must move with the armrest increasing complexity and cost

Engineering Contradiction:

Improvearmrest adjustabilityVSAvoidcontrol handle movement mechanism

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The armrest adjustment mechanism is separated from the control handle. The armrest can be adjusted independently along an arc-shaped path while the control handle remains stationary relative to the vehicle frame, eliminating the need for complex coupled movement mechanisms.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A virtual pivot point located in front of the armrest mechanism serves as an intermediary that defines the arc-shaped adjustment path. This pivot point allows the armrest to move independently without requiring the control handle to move, simplifying the overall system design.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Ease of operation

If the armrest allows adjustment to accommodate different elbow positions, then operator comfort improves, but maintaining neutral wrist position becomes more difficult

Engineering Contradiction:

Improveoperator comfortVSAvoidwrist position alignment

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The armrest adjustment follows an asymmetric arc-shaped path rather than a symmetric linear path. This asymmetric trajectory is specifically designed to maintain proper wrist alignment and neutral position while accommodating different elbow locations for operators of various heights.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The virtual pivot point acts as a geometric intermediary that ensures the armrest moves along a path maintaining ergonomic wrist positioning. By pivoting around this specific point, the armrest adjustment automatically preserves neutral wrist posture regardless of the operator's height.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9058052B2Adjustable armrest mechanism for a materials handling vehicle

Publication Date: 2015.06.16 CROWN EQUIP CORP

AI summary

An adjustable armrest mechanism is provided, which is adapted to be coupled to a vehicle frame. The armrest mechanism comprises a base fixed to the vehicle frame, armrest apparatus movably coupled to the base such that the armrest apparatus moves relative to the control handle and pivots about a virtual pivot point in front of the control handle, and a locking device for releasably locking the armrest apparatus to the base in one of at least two positions.