Compact Automobile Flap Force Assist With Nested Springs

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Solution Overview

Problem

Existing force assist arrangements for automobile flaps are bulky, inefficient, and hinder loading due to their size and design, with ropes being distant from the flap articulation when open, making it difficult to load items.

Innovation Solution

A compact force assist arrangement featuring a rope guide connected to a rotatable shaft, supported by levers and spring members, allowing the rope to be unwound when open and wound when closed, with spring members nested within a cup-shaped cylinder to provide torque assistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a volute spring is used to enroll the rope, then the spring can generate sufficient torque to wind the rope, but the assistance for the user is neglectable and the resulting package cannot be accommodated within the flap or body

Engineering Contradiction:
ImprovetorqueVSAvoidspace requirement
Core Design Contradiction:
ForceVSVolume of moving object

Solution Approach 1:

The spring members are nested within a cup-shaped cylinder, with the first spring member positioned inside the second spring member. This nesting arrangement allows both springs to occupy the same spatial envelope, dramatically reducing the volume required for the spring arrangement while maintaining the torque-generating capability. The cup-shaped cylinder contains both nested springs, enabling the entire assembly to fit within the flap or body structure.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Volume of moving object

If the rope is substantially unwound from the rope guide when the flap is open, then the rope guide can be compact, but the rope becomes very distant from the articulation of the flap, making it difficult to load items

Engineering Contradiction:
Improverope guide sizeVSAvoidloading convenience
Core Design Contradiction:
Volume of moving objectVSEase of operation

Solution Approach 1:

The force assist arrangement is divided into functionally independent segments: the rope guide assembly (with shaft and levers) is separated from the spring arrangement (nested within the cup-shaped cylinder). This segmentation allows the rope guide to be positioned close to the flap articulation for easy loading, while the spring members provide torque assistance from their nested position within the cup-shaped cylinder. The levers transmit force between these segmented components, enabling both compact size and operational convenience.

Inventive Principle:
Principle #1Segmentation

3Reliability

If the spring arrangement is arranged in a spring housing on the body, then the arrangement is protected, but the overall device complexity and space requirements increase

Engineering Contradiction:
ImproveprotectionVSAvoidstructural complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The cup-shaped cylinder serves multiple functions simultaneously: it acts as the housing for the spring arrangement, provides structural support, and serves as the mounting interface for the levers. By merging these functions into a single integrated component, the design eliminates the need for separate protective housings and mounting structures, thereby reducing overall device complexity while maintaining protection and structural integrity.

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

The arrangement is compact, firm, and efficiently assists in closing the flap, minimizing space requirements and allowing easy loading by directly transferring forces to the shaft, reducing material costs and noise, and enabling smooth operation.

Implementation Method 1

a first spring member configured as a helical spring; a second spring member configured as a helical spring; the spring members being nested the one into the other, in particular in a concentric manner

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4563779B1Force assist arrangement and automobile equipped therewith
Publication Date: 2025.10.08 EDSCHA ENG GMBH
  • EP4563779B1 patent drawingFigure 1
  • EP4563779B1 patent drawingFigure 2
  • EP4563779B1 patent drawingFigure 3

AI summary

The invention relates to a force assist arrangement for a flap (20) of an automobile (1), comprising a rope (41) connectable to one of the flap (20) and a body (10, 11) of the automobile (1); a rope guide (42) for enrolling the rope (41); and a spring arrangement (43) urging the rope guide (42) towards a closed position of the flap (20); wherein the rope (41) is substantially unwound from the rope guide (42) when the flap (20) is open, wherein the rope (41) is substantially wound on the rope guide (42) when the flap (20) is closed. A small-sized force assist arrangement for a flap and an automobile that provides a force supporting the user in closing the flap is characterized in that the rope guide (42) is connected to a rotatable shaft (44) for common rotation, that the shaft (44) is rotatably connected to a support member (45), that the spring arrangement (43) comprises a first end (431; 431') supported against a support area (45b) of the support member (45), and that the spring arrangement (43) comprises a second end (432; 432') supported against a drive area (441) of the shaft (44).