Lockable Gas Spring Energy Harvesting for Stretcher Battery Charging

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Solution Overview

Problem

Stretchers often face battery depletion due to insufficient charging, especially when not connected to mains power or when caregivers forget to recharge them.

Innovation Solution

The implementation of an energy harvesting system using a lockable gas spring with a turbine and electrical generator, which converts mechanical energy from the stretcher's movements into electrical energy to recharge the battery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the stretcher uses an on-board battery to power electrical components, then the stretcher can operate independently from mains power, but the battery charge depletes when the stretcher is not connected to mains power or when caregivers forget to recharge it

Engineering Contradiction:

Improveindependence from mains powerVSAvoidbattery charge availability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system enables the stretcher to charge its own battery by converting mechanical energy from normal stretcher operations (deck section adjustments, patient transfers) into electrical energy through the gas spring-turbine-generator mechanism, eliminating the need for external charging infrastructure and caregiver intervention

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system converts the previously wasted mechanical energy from stretcher movements into useful electrical energy to charge the battery, transforming what was simply operational movement into a beneficial charging source that resolves the battery depletion problem

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Ease of operation

If the stretcher is not connected to mains power during transport or when stationary away from outlets, then the stretcher maintains mobility and accessibility, but the battery charge is insufficient for the next use

Engineering Contradiction:

Improvemobility and accessibilityVSAvoidbattery charge sufficiency

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The system ensures continuous battery recharging by capturing and converting mechanical energy during every stretcher operation, including transport and positioning activities, so that the battery is continuously topped up whenever the stretcher is used rather than only during stationary charging events

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If the stretcher includes energy harvesting components, then the battery can be recharged from mechanical energy, but the device complexity increases

Engineering Contradiction:

Improvebattery charge availabilityVSAvoidenergy harvesting system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The gas spring serves dual functions: it provides the necessary mechanical assistance for deck section adjustment (original function) and simultaneously drives the turbine-generator to produce electrical energy (new function), eliminating the need for separate dedicated energy harvesting actuators and reducing overall system complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system merges the energy storage function of the gas spring with the energy generation function of the turbine-generator, creating an integrated mechanism where the same mechanical component (gas spring) performs both its traditional support role and the new power generation role

Inventive Principle:

Principle #5Merging (Combining)

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

This solution ensures a consistent supply of electrical energy to the stretcher's components by harnessing kinetic energy from the stretcher's use, reducing reliance on mains power and preventing battery depletion.

Implementation Method 1

A turbine receives fluid that flows out of the non-isolated compartment

Methodology Applied

Scientific EffectTurbine: Turbine

Implementation Method 2

An electrical generator is coupled to the turbine

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

An outflow check valve operates to resist fluid flow out of the non-isolated compartment and to admit ambient fluid into the non-isolated compartment

Methodology Applied

Scientific EffectPressure differential: Pressure Gradient

Data Source

PatentUS12343292B2Energy management for a stretcher or other occupant support

Publication Date: 2025.07.01 HILL ROM SERVICES INC

AI summary

An occupant support includes a framework with a frame and an orientation adjustable deck section that is supported by the frame. A lockable gas spring includes a piston assembly coupled to one of the frame and the deck section and a cylinder coupled to the other of the frame and the deck section. The piston assembly includes a piston and a connecting rod. The piston divides the interior of the cylinder into isolated and non-isolated compartments. The non-isolated compartment has an inlet and an outlet. An outflow check valve operates to resist fluid flow out of the non-isolated compartment and to admit ambient fluid into the non-isolated compartment. An inflow check valve operates to resist fluid flow into the non-isolated compartment and to enable fluid flow out of the non-isolated compartment. A turbine receives fluid that flows out of the non-isolated compartment. An electrical generator is coupled to the turbine.