Leaf Spring Suspension with S-Curved Leaves and Rubber Interlayers
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Solution Overview
Problem
Conventional leaf-spring suspension devices experience increased frictional resistance due to metal-to-metal contact between spring leaves, leading to reduced deflectability and comfort, and adverse effects on vehicle ride and driveability due to axle roll steer during vehicle cornering.
Innovation Solution
Incorporating interplate rubber members between the abutting ends of laminated spring leaves with paired, symmetrically S-shaped curved portions of different curvature radii, which accommodate relative displacement through shear strain, reducing frictional resistance and enhancing deflectability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If spring leaves are deflected at vertically unaligned positions, then the suspension structure is simple, but metal-to-metal contact occurs between leaves causing increased frictional resistance and reduced deflectability
Solution Approach 1:
A rubber member is introduced as an intermediary element between the spring leaves to eliminate direct metal-to-metal contact. The rubber member deforms elastically to accommodate relative displacement between leaves while preventing frictional resistance, thereby maintaining simple structure without compromising deflectability
Solution Approach 2:
The invention changes the material parameter at the contact interface from metal-to-metal to metal-to-rubber. This parameter change reduces the friction coefficient and allows greater deflectability while maintaining structural simplicity
2Ease of operation
If shackle pivotal movement accommodates spring expansion and contraction, then the suspension functions, but the axle follows a slantwise rearward ascending trajectory causing axle or roll steer
Solution Approach 1:
The spring leaves are designed with asymmetric curved portions having different curvature radii between upper and lower leaves. This asymmetry creates a geometric constraint that counteracts the slantwise trajectory, reducing axle or roll steer while maintaining the necessary suspension function through shackle pivotal movement
3Stability of the object's composition
If frictional resistance is increased to constrain relative displacement between spring leaves, then structural stability is improved, but the spring constant increases reducing ride comfort
Solution Approach 1:
The rubber member serves as a mediator that provides elastic constraint rather than frictional constraint. It allows controlled relative displacement between leaves through elastic deformation, maintaining structural stability while minimizing the force required, thereby keeping the spring constant low for improved ride comfort
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 design reduces the spring constant, improves dynamic characteristics, and minimizes axle displacement during vehicle roll, resulting in enhanced comfort and reduced axle roll steer, thereby improving vehicle ride quality and driveability.
Implementation Method 1
any relative displacement between the spring leaves upon deflecting of the same may be accommodated by shear strain of the interplate rubber members
Implementation Method 2
the curved portions of the upper spring leaf having longitudinally outward bend starts longitudinally outward of longitudinally outward bend starts of the curved portions of the lower spring leaf and having longitudinally inward bend ends longitudinally inward of longitudinally inward bend ends of the curved portions of the lower spring leaf
Data Source
AI summary
Interplate rubber members 15 are interposed between abutting front and rear ends of spring leaves 2A and 2B. The spring leaves 2A and 2B have paired curved portions 14A and 14B, respectively, which are symmetrically S-shaped with respect to a connected position of an axle 3 in side view. A curvature radius of continuous and mutually reverse curves of each of the curved portions 14A of the upper spring leaf 2A is greater than a curvature radius of continuous and mutually reverse curves of each of the curved portions 14B of the lower spring leaf 2B. The upper curved portions 14A have longitudinally outward bend starts longitudinally outward of longitudinally outward bend starts of the lower curved portions 14B and have longitudinally inward bend ends longitudinally inward of longitudinally inward bend ends of the lower curved portions 14B.