Differential Drive Caster for Maneuverable Patient Support Wheels
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Solution Overview
Problem
Traditional patient support apparatuses face issues with maneuverability in tight spaces and varying patient weights due to non-castered motorized wheels, which require complex mechanisms for adjustable down force, increasing cost and weight.
Innovation Solution
The use of differential drive casters with pancake motors and integrated planetary gear sets, along with angle sensors, allows for swiveling and propulsion control, enhancing maneuverability and adaptability to different patient weights.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If non-castered motorized wheels are used to propel patient support apparatus, then propulsion function is achieved, but maneuverability in tight spaces deteriorates due to inability to swivel
Solution Approach 1:
The patent combines the propulsion motor and caster swivel mechanism into an integrated unit. The motorized wheel assembly includes a motor, wheel, and caster mechanism that work together as a single integrated component, eliminating the need for separate raising/lowering mechanisms while maintaining both propulsion and swiveling capabilities.
Solution Approach 2:
The motorized wheel assembly serves multiple functions simultaneously: it provides propulsion when the motor drives the wheel, enables steering through caster swiveling, and eliminates the need for separate raising/lowering mechanisms. This multi-functional design improves maneuverability while reducing overall system complexity.
2Force
If down force is increased to prevent wheel slip on ramps, then traction is improved, but other wheels (casters) are lifted off the floor causing teetering
Solution Approach 1:
The patent employs a dynamic down force adjustment mechanism that automatically adapts the force applied by the motorized wheel to the floor. The mechanism includes a spring-loaded or adjustable force system that increases down force when needed for traction (such as on ramps) while decreasing it during normal operation to prevent caster lift and maintain stability.
Solution Approach 2:
The system changes the down force parameter dynamically based on operating conditions. An adjustable mechanism allows the down force to be modified according to the patient weight and terrain conditions, optimizing traction without causing apparatus teetering or caster lift.
3Adaptability or versatility
If adjustable down force mechanisms are added to accommodate varying patient weights, then adaptability is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements a dynamic adjustment mechanism that automatically adapts to varying patient weights and operating conditions. The adjustable down force system responds to load changes and terrain variations without requiring complex manual intervention, maintaining adaptability while controlling mechanism complexity through automated sensing and adjustment.
Solution Approach 2:
The motorized wheel assembly includes self-adjusting features that automatically adapt to different patient weights and floor conditions. The system monitors its own operating parameters and adjusts down force accordingly, eliminating the need for manual adjustment mechanisms and reducing overall system complexity while maintaining high adaptability.
4Device complexity
If single drive wheel is used at center of patient support apparatus, then propulsion is simplified, but maneuverability in tight spaces deteriorates
Solution Approach 1:
The patent merges the single central drive wheel with a caster mechanism to create an integrated motorized caster wheel. This combination allows the wheel to function as both a propulsion element and a steering element, maintaining simplified propulsion system complexity while dramatically improving maneuverability in tight spaces through the ability to swivel and navigate obstacles.
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 cost-effective, lightweight, and highly maneuverable patient support apparatuses that operate smoothly on various surfaces and patient weights without complex mechanisms.
Implementation Method 1
Each of the first and second pancake motors may include a respective integrated planetary gear set
Implementation Method 2
an angle sensor that may produce a signal that is usable by a controller of the patient support apparatus to determine a direction in which the differential drive caster may be driven
Data Source
AI summary
A dual-wheel steerable motorized caster has internal motors that are operated at different speeds to swivel a pair of wheels about a caster swivel axis. The motors are operated at the same speed to propel an apparatus to which the dual-wheel steerable motorized caster is coupled along an underlying surface such as a floor in a drive direction without swiveling the pair of wheels about the caster swivel axis. A patient support apparatus has one or more of such dual-wheel steerable motorized casters.