Eccentric Screw-Nut Damper Height Adjustment

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Solution Overview

Problem

Existing damper and spring units for vehicle suspensions with electro-mechanical height adjustment devices are complex, expensive, and require significant space, especially in the radial direction, and often necessitate the use of anti-rotation means that can negatively impact performance.

Innovation Solution

A damper and spring unit with an electro-mechanical adjustment device featuring a screw and nut motion conversion mechanism arranged eccentrically with respect to the damper axis, eliminating the need for dedicated anti-rotation means and allowing for independent sizing from the damper's external size, utilizing a guide sleeve for support and load management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If multiple pairs of screws and nuts are used for height adjustment, then the adjustment function is achieved, but the device complexity and space requirements increase significantly

Engineering Contradiction:
Improveheight adjustment functionVSAvoidnumber of screw and nut pairs
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The patent combines multiple adjustment functions into a single screw-nut mechanism. The first screw and nut pair handles both height adjustment and inherently prevents spring plate rotation through its specific geometric arrangement, eliminating the need for separate anti-rotation mechanisms that would be required in conventional multi-pair designs.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The single screw and nut mechanism performs multiple functions simultaneously: it adjusts the vertical position of the spring plate and prevents its rotation relative to the damper. This multi-functional design replaces what would traditionally require multiple separate mechanisms, reducing overall device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Stability of the object's composition

If dedicated anti-rotation means are added to prevent spring plate rotation, then rotation is prevented, but the device complexity and manufacturing cost increase

Engineering Contradiction:
Improvespring plate rotation preventionVSAvoidadditional anti-rotation mechanisms
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The screw and nut mechanism is designed to automatically prevent spring plate rotation through its own geometric configuration without requiring additional anti-rotation components. The inherent geometry of the single screw-nut arrangement creates a self-locking effect that prevents rotation while maintaining adjustment functionality.

Inventive Principle:
Principle #25Self-service

3Adaptability or versatility

If the screw and nut mechanism is designed to fit conventional dampers, then adaptability is improved, but the sizing may be constrained by the damper's external dimensions

Engineering Contradiction:
Improvecompatibility with conventional dampersVSAvoidscrew and nut mechanism dimensions
Core Design Contradiction:
Adaptability or versatilityVSLength of moving object

Solution Approach 1:

The patent positions the screw and nut mechanism in an eccentric arrangement relative to the damper axis, utilizing spatial dimensions efficiently. This dimensional arrangement allows the mechanism to achieve its functional requirements without being constrained by the external diameter of the damper, enabling adaptability across different damper sizes.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 prevents spring plate rotation relative to the damper without additional anti-rotation mechanisms, reduces size and manufacturing costs, and allows for easy installation on conventional units, with the screw and nut sizing being independent of the damper's external diameter.

Implementation Method 1

a screw and nut motion conversion mechanism arranged to convert the rotary motion generated by the electric motor into a translation motion of the spring plate, said motion conversion mechanism comprising one single screw arranged to be driven into rotation about its own axis by the electric motor and one single nut that meshes with the screw and is drivingly connected for translation with the spring plate

Methodology Applied
Scientific EffectScrew and nut motion conversion: Screw

Implementation Method 2

The adjustment device further comprises a guide sleeve which is arranged around the cylinder of the damper so as to be slidable along the axis of the damper, is rigidly connected to the spring plate and works as a guide for a support arm that carries the nut or the screw of the motion conversion mechanism

Methodology Applied
Scientific EffectMechanical guidance:

Data Source

PatentEP3710290B1Damper and spring unit for a vehicle suspension provided with an electro-mechanical adjustment device for adjusting the vertical position of the spring
Publication Date: 2021.12.29 MARELLI SUSPENSION SYST ITAL SPA
  • EP3710290B1 patent drawingFigure 1
  • EP3710290B1 patent drawingFigure 2

AI summary

The damper and spring unit comprises: a damper (10) having a cylinder (14) and a rod (16) which extend along a first axis (z); a spring plate (18) which is arranged around the cylinder (14) and is slidable with respect to the latter along the first axis (z); a spring (12) resting at its bottom on the spring plate (18); and an electro-mechanical adjustment device in- terposed between the cylinder (14) and the spring plate (18) for adjusting in a continuous and controlled manner the vertical position of the bottom end of the spring (12) and, thus, allowing to adjust the height of the vehicle from the ground. The adjustment device comprises an electric motor (22) arranged to generate a rotary motion and a motion conversion mechanism (24, 26) having one screw (24) which extends along a second axis (z') parallel to the first axis (z), but spaced therefrom, and is arranged to be driven into rotation by the electric motor (22) about the second axis (z'), and a nut (26) which meshes with the screw (24) and is drivingly connected for translation with the spring plate (18).