Vehicle Base Unit Suspension with Adjustable Biasing Force
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Solution Overview
Problem
Mobile elevating work platforms (MEWPs) with rigid chassis experience instability on uneven surfaces, leading to loss of drive power and operator discomfort due to wheels lifting off the ground, and existing suspension mechanisms struggle to balance stability and slip prevention.
Innovation Solution
A mobile elevating work platform with a chassis and wheels mounted on a suspension mechanism that includes a pivotable swing arm with a biasing mechanism, featuring an actuator to adjust the biasing force, ensuring stability by maintaining contact with the ground on uneven surfaces while minimizing slip risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid chassis is used to ensure stability, then the platform stability is improved, but the wheels may lift off the ground on uneven surfaces causing loss of drive power and operator discomfort
Solution Approach 1:
The patent applies dynamics by replacing the rigid chassis with a suspension mechanism that allows the swing arms to pivot dynamically. The swing arms can pivot downward when wheels lift on uneven terrain, maintaining wheel-ground contact and drive power while preserving overall platform stability through the pivotable connection to the chassis.
2Reliability
If the biasing force is reduced to allow the wheel to maintain ground contact, then the slip risk is reduced, but the platform stability is compromised
Solution Approach 1:
The system dynamically adjusts the biasing force through actuator control. The actuator can increase biasing force when needed to maintain wheel contact and prevent slip, while allowing the swing arm to pivot to positions that preserve platform stability. This dynamic control resolves the contradiction by adapting the biasing force to actual operating conditions.
Solution Approach 2:
The patent changes the parameter of biasing force dynamically using an actuator. By adjusting the biasing force parameter based on operational needs, the system can maintain adequate wheel-ground contact for drive power while preventing excessive force that would compromise platform stability. This parameter adjustment resolves the technical contradiction.
3Reliability
If the swing arm is allowed to pivot downward to maintain wheel contact, then drive power is maintained, but the operator may perceive incorrect instability
Solution Approach 1:
The patent applies visual feedback (analogous to color changes) by providing indicators that show the swing arm position and system status to the operator. This visual information helps the operator understand that swing arm movement is a normal response to uneven terrain and does not indicate actual instability, thereby maintaining operator confidence while allowing the drive wheels to maintain contact.
4Reliability
If a suspension mechanism is added to allow wheel movement on uneven ground, then wheel contact is improved, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the chassis into modular sections connected by pivotable swing arms. Each swing arm independently supports a wheel and can pivot to maintain contact, allowing the system to handle uneven terrain without requiring a completely complex active suspension system for each wheel. This segmented approach reduces overall complexity while maintaining reliability.
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 solution provides enhanced operator confidence and maintains drive power by ensuring all wheels remain in contact with the ground, contributing to the platform's stability without compromising weight distribution, while allowing for adjustable force to balance stability and slip prevention.
Implementation Method 1
a biasing mechanism arranged to exert an upwards biasing force on the suspension element to urge the suspension element upwards towards the upper position
Implementation Method 2
said biasing mechanism including an actuator operable to adjust the biasing force so that, in a first operating condition the biasing force is greater than the force needed to maintain the suspension element in engagement with the stop member when the wheel is suspended
Data Source
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AI summary
A base unit for a vehicle such as a mobile work platform includes a chassis (12) and a plurality of wheels (14, 16), at least one of which is mounted by a suspension element (18) which pivots relative to the chassis (12) about a horizontal axis (20) between upper and lower positions. A stop member (23) engages the suspension element in the upper position to limit upwards movement. A biasing mechanism (24) including a spring (40) exerts a biasing force on the suspension element (18) to urge the suspension element upwards. The biasing mechanism also includes an actuator (28) to adjust the biasing force to be either greater than or less than the force needed to maintain the suspension element in engagement with the stop member.