Suspension Jounce Bumper Caster Control
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Solution Overview
Problem
Certain vehicle suspension configurations experience undesirable caster windup due to the interaction of springs, dampers, and jounce bumpers, leading to issues such as wheel contact with the body, bottoming out, and changes in camber and toe angles, which negatively impact vehicle performance.
Innovation Solution
A suspension assembly that includes a knuckle, control arms, a spring, a damper, and a jounce bumper, where the spring and jounce bumper are positioned on opposite sides of the kingpin axis, and the damper is configured to balance moments on the knuckle, maintaining a desired caster angle by adjusting their lengths and contact points as the knuckle moves between positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the spring, damper, and jounce bumper are configured in typical suspension arrangements, then the suspension can support the wheel and dampen oscillations, but these components contribute to undesirable caster windup that negatively impacts vehicle performance
Solution Approach 1:
The patent positions the spring and jounce bumper asymmetrically on opposite sides of the kingpin axis rather than in symmetric or conventional locations. This asymmetric arrangement creates opposing moments that balance each other, preventing caster windup while maintaining suspension support and damping functions.
Solution Approach 2:
The spring and jounce bumper are configured to generate counteracting moments about the kingpin axis. The spring moment and jounce bumper moment work in opposition to each other, creating a balancing effect that eliminates caster windup while both components continue to perform their primary functions of supporting and damping the suspension.
2Ease of operation
If the jounce bumper is positioned to contact the striker during suspension compression, then it can prevent bottoming out and improve ride comfort, but it can also contribute to caster windup when compressed
Solution Approach 1:
The jounce bumper is positioned asymmetrically on one side of the kingpin axis while the spring is positioned on the opposite side. This asymmetric placement ensures that when the jounce bumper contacts the striker during compression, it generates a moment that is balanced by the opposing spring moment, preventing caster windup while maintaining ride comfort benefits.
Solution Approach 2:
The patent converts the potentially harmful effect of jounce bumper compression (caster windup) into a beneficial balancing moment. By positioning the jounce bumper opposite the spring relative to the kingpin axis, the compression force that would normally cause caster windup instead creates a counteracting moment that balances the spring moment, eliminating the harmful effect.
3Stability of the object's composition
If the spring is positioned to bias the knuckle toward a rest position, then it can maintain suspension geometry, but it can also generate moments that cause caster windup when the suspension moves from rest position
Solution Approach 1:
The spring is positioned asymmetrically on one side of the kingpin axis while the jounce bumper is positioned on the opposite side. This asymmetric configuration ensures that the spring moment generated during suspension movement is always balanced by an opposing moment from the jounce bumper, preventing caster windup while the spring continues to maintain suspension geometry.
Solution Approach 2:
The spring and jounce bumper are arranged to create counterbalancing moments about the kingpin axis. As the suspension moves from rest position, the spring generates a moment that is countered by the jounce bumper moment, eliminating caster windup while the spring maintains its function of biasing the knuckle toward the rest position and preserving suspension geometry.
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 configuration effectively balances moments to maintain a desired caster angle, reducing caster windup and improving vehicle handling and ride comfort by ensuring that the spring, damper, and jounce bumper moments approximately cancel each other out during suspension travel.
Implementation Method 1
The spring biases the knuckle toward the first position
Implementation Method 2
The damper dampens oscillation between the frame and the knuckle
Data Source
AI summary
A suspension includes a jounce bumper, and a striker. A spring biases the knuckle toward a first position. One of the spring and the jounce bumper is disposed forward of a kingpin axis of the knuckle and the other of the spring and the jounce bumper is disposed rearward of the kingpin axis. When in a first position, the spring is a first spring length. When in a second position, the spring is shorter than in the first position and the jounce bumper contacts the striker. When in a third position, the spring is shorter than in the second position and the jounce bumper is compressed against the striker to be shorter than in the second position. When moving between the second and third positions, the spring and jounce bumper impart moments on the knuckle that approximately balance each other to maintain a desired caster angle.