Leaf Spring Torsionally Elastic Coupling Design

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Solution Overview

Problem

Existing leaf springs in torsionally elastic couplings have limited capability to compensate radial, axial, and angular displacements between rotary members, restricting their application in drive trains with high elastic requirements.

Innovation Solution

A leaf spring design featuring three angled arms connected by smoothly curved bends, with specific angular arrangements and optional slots and elastomeric layers, allowing for enhanced compensation of displacements while maintaining torque transmission efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a U-shaped leaf spring with two arms is used, then the structure is simple and easy to manufacture, but the capability to compensate radial, axial and angular displacements is limited

Engineering Contradiction:
Improvedisplacement compensation capabilityVSAvoidleaf spring structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The leaf spring is divided into three separate arms (first arm, second arm, third arm) instead of a single U-shaped structure. Each arm can independently deform to compensate for different types of displacements, thereby enhancing the overall displacement compensation capability while maintaining a relatively simple segmented structure

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The leaf spring structure transitions from a two-dimensional U-shape to a three-dimensional configuration with arms extending in different directions and angles. The first arm extends radially inward, the second arm extends circumferentially, and the third arm extends radially outward, creating a spatial structure that can accommodate multi-directional displacements

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

2Adaptability or versatility

If the leaf spring structure is made more complex to compensate larger displacements, then displacement compensation improves, but the torque transmission efficiency may be impaired

Engineering Contradiction:
Improvedisplacement compensation capabilityVSAvoidtorque transmission efficiency
Core Design Contradiction:
Adaptability or versatilityVSPower

Solution Approach 1:

Different portions of the leaf spring are designed with different structural characteristics optimized for their specific functions. The first arm is designed for radial compression/tension, the second arm for circumferential bending, and the third arm for radial tension/compression. This local optimization ensures that each segment contributes effectively to both displacement compensation and torque transmission without unnecessary complexity

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The angles between the arms are carefully selected within specific ranges (acute angle between second and third arm: 5°-45°, angles between first arm and second arm, and third arm and second end portion: 80°-100°). These parameter optimizations balance the structural complexity with torque transmission efficiency, ensuring that the spring maintains sufficient stiffness for power transmission while accommodating the required displacement compensation

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If the acute angle between the second and third arm is increased to compensate more displacements, then displacement compensation improves, but torque transmission may be impaired

Engineering Contradiction:
Improvedisplacement compensation capabilityVSAvoidtorque transmission capability
Core Design Contradiction:
Adaptability or versatilityVSForce

Solution Approach 1:

The acute angle between the second and third arm is optimized within a specific range of 5° to 45°. This parameter optimization ensures that the structure can compensate for sufficient displacements while maintaining adequate torque transmission capability. The constrained angle range prevents excessive flexibility that would compromise power transmission

Inventive Principle:
Principle #35Parameter changes

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 new leaf spring design effectively compensates larger radial, axial, and angular displacements, enabling its use in drive trains with high elastic engine supports and providing overload protection with increased torsional stiffness and damping properties.

Implementation Method 1

a first arm (4), a second arm (5) and a third arm (6) which are arranged in sequence between a first end portion (2) and a second end portion (3) of the leaf spring (1) and are connected by bends (7, 8)

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

These layers of elastomeric material are perpendicular to said common plane of the L-shaped portion and are thus exposed to shear stress to provide increased damping

Methodology Applied
Scientific EffectDamping: Damping

Data Source

PatentEP3284968B1Leaf spring and torsionally elastic coupling including same
Publication Date: 2020.03.11 GEISLINGER GROUP GMBH
  • EP3284968B1 patent drawingFigure 1~2
  • EP3284968B1 patent drawingFigure 3
  • EP3284968B1 patent drawingFigure 4

AI summary

A leaf spring, in particular for use in a torsionally elastic coupling, has a first end portion (2) and a second end portion (3) which are movable relative to each other against an elastic reactive force, a first L-shaped portion (9) having a first arm (4) and a second arm (5) and extending from said first end portion (2), and a third arm (6) extending from said second end portion (3). The second arm (5) of the L-shaped portion (9) and the third arm (6) are connected through a bend (8). The third arm (6) extends from the bend (8) in a direction towards the first arm (4) of the L-shaped portion (9) and at an acute angle (α) to the second arm (5) of the L-shaped portion (9).