Jounce Bumper Undercut Geometry for Flat Stiffness
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Solution Overview
Problem
Existing jounce bumpers fail to produce a flat stiffness curve, leading to inconsistent ride and handling due to constant thickness and spherical or elliptical geometries that do not effectively absorb shocks and vibrations across various driving conditions.
Innovation Solution
The introduction of an undercut in the inner diameter of the jounce bumper with varying thickness and radiused corners, creating a more complex geometry that maintains a consistent and soft entry curve, improving ride and handling by altering the stiffness curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a spherical or elliptical nose with constant thickness is used, then the manufacturing is simple, but the stiffness curve shows dramatic dips leading to poor ride and handling
Solution Approach 1:
The patent applies local quality by introducing an undercut region at the base of the nose that creates variable thickness distribution. This localized geometric modification changes the stiffness characteristics specifically in the critical compression region without affecting the overall spherical or elliptical shape, thereby improving the stiffness curve while maintaining manufacturing feasibility
Solution Approach 2:
The patent transitions from a two-dimensional constant thickness profile to a three-dimensional variable thickness profile by adding the undercut feature. This dimensional change allows the nose geometry to have different thicknesses at different locations, creating a more sophisticated stiffness progression that eliminates dramatic dips in the stiffness curve
2Device complexity
If the inner surface mirrors the outer spherical or elliptical geometry, then the structure is simple, but the stiffness curve cannot be flattened
Solution Approach 1:
The patent breaks the mirroring symmetry by introducing an undercut region where the inner surface geometry differs from the outer surface geometry. This localized asymmetry in the base region allows independent control of stiffness characteristics without complicating the overall spherical or elliptical nose shape
Solution Approach 2:
The patent segments the nose geometry into distinct regions: the upper spherical or elliptical portion with constant or varying thickness, and the lower undercut region with specific geometric features. This segmentation allows each region to be optimized independently for its specific function in the compression sequence
3Ease of manufacture
If constant thickness is used throughout the nose, then manufacturing is easier, but shock absorption and vibration damping are insufficient across various driving conditions
Solution Approach 1:
The patent applies local quality by creating different thickness regions within the nose structure. The variable thickness distribution, particularly the undercut region, allows different parts of the nose to engage at different compression stages, providing adapted shock absorption characteristics for various impact severities and driving conditions
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 improved geometry results in a consistent and soft entry stiffness, enhancing ride quality and handling by maintaining a flat spring rate during initial compression, thus reducing harshness and improving steering stability.
Implementation Method 1
The jounce bumper may be made of micro cellular urethane
Implementation Method 2
The corner where the two sidewall surfaces meet the innermost surface of the undercut are radiused so as to create a smooth transition
Data Source
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AI summary
A jounce bumper for mounting in a vehicle suspension system having a bore extending therethrough, the bore configured to receive the piston rod, a nose having a predetermined inner diameter and a predetermined outer diameter, the nose being generally spherical or elliptical shaped and an undercut within the jounce bumper in the bore of the jounce bumper, the undercut creating an ununiformed thickness between the predetermined inner diameter and the predetermined outer diameter so as to provide improved handling characteristics of the jounce bumper.