Patient Lift Leg Support Spring Return and Telescopic Boom

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Solution Overview

Problem

Existing patient lift apparatuses face challenges in adjustability of the boom portion length and comfort during patient transfer, with known solutions not fully addressing the need for robustness, ease of handling, and improved patient comfort.

Innovation Solution

The patient lift apparatus features a leg/knee support with a retaining device and a pivotable outer casing, coupled with spring elements to maintain a default position, and a telescopic boom portion with an indexing mechanism for adjustable length, enhancing adjustability and comfort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a telescopic arm with pin-and-hole arrangement is used to allow adjustment of the inner member at predefined positions, then adjustability of the boom portion is improved, but clearance or play between inner and outer members causes unwanted movement and reduces patient comfort

Engineering Contradiction:
Improveadjustability of boom portionVSAvoidunwanted movement of inner member
Core Design Contradiction:
Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the traditional pin-and-hole mechanical adjustment system with a continuous telescopic mechanism where the inner member can be positioned at any point along its travel path. This substitution eliminates the discrete positioning constraints and clearance issues inherent in pin-and-hole arrangements, providing smooth continuous adjustment without unwanted movement or play between members.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a dynamic locking mechanism that allows the telescopic arm to be adjusted continuously along its length and locked at any desired position. The locking mechanism engages at the current position rather than requiring pre-defined holes, enabling the system to adapt dynamically to different patient needs while maintaining stability without clearance-induced movement.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If the leg/knee support is made releasable from the supporting frame by actuating a thumbscrew, then ease of operation is improved, but the guide portion forming an integral part of the frame increases device complexity

Engineering Contradiction:
Improveease of releasing leg/knee supportVSAvoidintegrated guide portion
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent divides the leg/knee support system into separable components: a support mount attached to the supporting frame and a leg/knee support assembly that can be independently attached and detached. This segmentation allows the guide portion to be part of the fixed frame structure while the leg/knee support can be easily released without requiring complex integrated mechanisms, simplifying the overall system while maintaining ease of operation.

Inventive Principle:
Principle #1Segmentation

3Ease of manufacture

If a simple pin-and-hole arrangement is used for adjusting the telescopic arm, then ease of manufacture is improved, but the necessary clearance between members reduces patient comfort

Engineering Contradiction:
Improvesimplicity of adjustment mechanismVSAvoidclearance causing patient discomfort
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the simple pin-and-hole adjustment mechanism with a continuous telescopic system that eliminates clearance-induced movement. The new system maintains manufacturing simplicity through standardized components while removing the harmful clearance effect by providing continuous contact and positioning capability along the entire travel path of the inner member.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 improved adjustability and comfort during patient transfers, ensuring robustness and ease of operation for both patients and caregivers, while maintaining the apparatus's functionality as a stand-assist hoist.

Implementation Method 1

a spring element coupling the outer casing to the retaining device, which spring element is configured to bring the outer casing to a default position with respect to the retaining device when no external force is applied onto the outer casing

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP4233824B1Patient lift apparatus
Publication Date: 2025.01.29 INVACARE INT GMBH
  • EP4233824B1 patent drawingFigure 1
  • EP4233824B1 patent drawingFigure 2
  • EP4233824B1 patent drawingFigure 2A

AI summary

There is described a patient lift apparatus (1) comprising a supporting frame (10), a boom portion (18) connected to the supporting frame (10) via a pivot joint (PJ1) to allow the boom portion (18) to pivot with respect to the supporting frame (10) about a pivot axis (PA1), a boom actuator (15) to mechanically assist pivotal movement of the boom portion (18) with respect to the supporting frame (10), and a leg/knee support (50) connected to the supporting frame (10). The leg/knee support (50) comprises a retaining device (51) configured to cooperate with a support mount (120) provided on the supporting frame (10) to secure the leg/knee support (50) onto the supporting frame (10), the leg/knee support (50) being configured to be partly pivotable with respect to the support mount (120) about a pivot axis (PA3) and within a defined pivoting range. The leg/knee support (50) further comprises an outer casing (500) configured to be pivotable with respect to the retaining device (51) about the pivot axis (PA3) and within the defined pivoting range, as well as at least one spring element (511, 512) coupling the outer casing (500) to the retaining device (51). The at least one spring element (511, 512) is configured to bring the outer casing (500) to a default position with respect to the retaining device (51) when no external force is applied onto the outer casing (500).